As we conclude our exploration of shipping pollution, this blog focuses on a lesser-known yet equally pressing issue: the pollutive impacts of shipbreaking. In particular, a recent study measuring toxic heavy metal concentrations at Bangladesh’s shipbreaking sites by Ali et al (2022), has resurfaced environmental concerns about shipbreaking activities around the world. 

What is shipbreaking and why is it pollutive? 

Shipbreaking refers to the act of breaking down retired ships for the recycling of valuable materials such as wood and steel (Abdullah et al., 2013). However, several studies have previously raised concerns about the highly pollutive nature of shipbreaking– largely due to the spillage and leakage of hazardous elements (Reddy et al., 2004; Hossain & Islam, 2006; Neser et al., 2012; Pasha et al., 2012). This is because ships being scrapped contain many different hazardous wastes. These include: 

• Heavy metals in the form of mercury, lead, and arsenic can be found in electric wastes such as fluorescent light tubes, thermometers, batteries, electrical switches, light fittings, and fire detectors. A large amount of copper is present in various electrical wiring, while iron forms a big part of the ship’s body. (Baura et al., 2017).
• Chromium can be found in ballast water (mentioned in blog 2) (Baura et al., 2017)
• Up to thousands of litres of petroleum hydrocarbons (e.g. Engine oil, blige oil, hydraulic and lubricant oil), as well as sealants which contain hazardous pentachloro benzene (Al-Mamun et al., 2017). 

As aforementioned, through spillage and discharge, these hazardous wastes are then leaked and mixed into coastal environments, contaminating beach sediments, sea and groundwater (Hasan et al., 2013). The toxicity of these pollutants subsequently poses a threat to marine biodiversity and to human public health (Ali et al., 2022). This is especially so for heavy metals, which not only have the propensity to bioaccumulate but are also non-biodegradable (Siddiquee et al., 2012). 

Case study: Chittagong shipbreaking yard, Sitakunda

The Chittagong shipbreaking yard, along the 20km coastal strip of Sitakunda, is the world’s largest shipbreaking yard, handling about a fifth of the world’s total shipbreaking (pathfriend-bd, n.d.). 

In Ali et al (2022) study of toxic metal pollution in the Sitakunda shipbreaking area in Bangladesh, their sampling of the concentration of four toxic metals (As, Cr, Cd, and Pb) in water and sediment at 10 different sampling sites over summer and winter (Figure 1), has yielded the following key results:  

1. Concentration of all four toxic metals (As, Cr, Cd, and Pb) exceeded WHO recommended acceptable limits (Table 1). 
2. Metal pollutive index (MPI) of water quality (derived by Mohan et al., 1996) revealed that MPI levels recorded (Range of 140.12 to 402.15) exceeded the critical score of 100 (MPI >100 is considered as polluted). 
3. Geoaccmulation index (measurement of contamination of toxic metals in sediments, derived by Muller, 1969) revealed Cd to be “strongly contaminated,” Pb to be “moderately contaminated,” and As was found to be “uncontaminated to moderately contaminated” (Table 2).
4. Calculation of Potential ecological risk index (Eri) and the Risk Factor (RI), which sums of all risk factors for toxic metals in the sediments (derived by Hakanson, 1980), has suggested that  the Sitakunda ship breaking area was at very high ecological risk due to metals pollution (Table 3). 
5. As and Cd showed significant seasonal variation (water and sediment) seasons, while Pb and Cr had no seasonal impact.

Overall, Ali et al. (2022) study revealed significant levels of toxic metal pollution present in the coastal strip of Sitakunda, as a result of shipbreaking activities. Crucially, the area currently faces high ecological risk, as a result of high levels of metal pollution.

Figure 1: Map showing the sampling sites of the Sitakunda ship-breaking area of the Bengal coast, Bangladesh. (Ali et al., 2022).

Table 1: Comparison of results of concentration of four toxic metals (As, Cr, Cd, and Pb) with WHO recommended allowable limit. (extracted from Ali et al., 2022)

Table 2: Comparison of results of geo-accumulation index (Igeo) of four toxic metals (As, Cr, Cd, and Pb). A seven-tiered classification system of Igeo provided by Muller (1969) is defined as Igeo ≤ 0-practically unpolluted; 0 ≤ Igeo ≤ 1-unpolluted to moderately polluted; 1 ≤ Igeo ≤ 2-moderately polluted; 2 ≤ Igeo ≤ 3-moderately to strongly polluted; 3 ≤ Igeo ≤ 4-strongly polluted; 4 ≤ Igeo ≤ 5-strongly to extremely polluted; and 5 < Igeo-extremely polluted (extracted from Ali et al., 2022).

Table 3: Potential ecological risks (PERI) and Risk Index (RI) for toxic metals in sediment investigated from the Bay of Bengal coast around the shipbreaking area of Bangladesh for summer and winter. Eri is defined as the monomial potential ecological risk factor, while RI determines the extent to which toxic metal pollution had contaminated the sediments, based on the toxicity of poisonous metal pollution and the environment’s response (Hakanson, 1980). The potential ecological risk for single metal (Eri)) follows a level as low risk ( Eri)< 40); moderate risk (40 ≤ Eri)< 80); considerable risk (80 ≤ Eri)< 160); high risk (160 ≤ Eri)〈320); very high risk ( Eri)≥ 320). Considering the total toxic metals, RI follows a ranking with: low risk (RI < 95); moderate risk (95 ≥ RI < 190); considerate risk (190 ≥ RI < 380); very high risk (RI > 380) (extracted from Ali et al., 2022).

Negative ecological impacts of toxic metal pollution, on marine biodiversity and to human health

As explored by several authors, toxic metal pollutants have negative effects on marine organisms. Table 4 highlights several of the effects that toxic metals have on marine organisms. Furthermore, as such heavy metals have high accumulation potential, they accumulate in aquatic organisms as well as through agricultural soil, rising levels of toxic metals contamination also have a direct negative impact on human health as they are such toxic metals are transferred through the food chain (Ahmed et al., 2020; Bryan & Hummerstone, 1977; Lee et al., 2019; Proshad et al., 2021). 

Table 4: The effects of toxic metals on marine organisms. (Sadiq, 1992).

Moving forward 

It is important to note that while Ali et al (2022) study has highlighted the effects of shipbreaking on increasing toxic metal concentration, it was not the first study to do so. Siddiquee et al (2012) have similarly found high concentrations of several heavy metals (Zn, Pb, Cr) in the same area– the Chittagong shipbreaking yard, 10 years ago (Figure 2). Therefore, while these studies have highlighted the high concentration of toxic metals present at such shipbreaking sites, little action has been taken to address this issue, despite their negative pollutive impacts on the surrounding biodiversity and human health. This further supports previous blogposts’ arguments that the pollutive impacts of the shipping industry are often sidelined. Moving forward, more concrete actions need to be taken in order to better mitigate and reduce the pollutive impacts on the shipbreaking industry (Ali et al., 2022). 

Figure 2: Comparison of trace metals in affected, controlled and standard values. (Siddiquee et al., 2012)

References

Abdullah, H. M., Mahboob, M. G., Banu, M. R., & Seker, D. Z. (2013). Monitoring the drastic growth of ship breaking yards in Sitakunda: A threat to the coastal environment of Bangladesh. Environmental Monitoring and Assessment, 185(5), 3839–3851. https://doi.org/10.1007/s10661-012-2833-4

Ahmed, A. S. S., Hossain, M. B., Semme, S. A., Babu, S. M. O. F., Hossain, K., & Moniruzzaman, M. (2020). Accumulation of trace elements in selected fish and shellfish species from the largest natural carp fish breeding basin in Asia: A probabilistic human health risk implication. Environmental Science and Pollution Research, 27(30), 37852–37865. https://doi.org/10.1007/s11356-020-09766-1

Ali, M. M., Islam, Md. S., Islam, A. R. Md. T., Bhuyan, Md. S., Ahmed, A. S. S., Rahman, Md. Z., & Rahman, Md. M. (2022). Toxic metal pollution and ecological risk assessment in water and sediment at ship breaking sites in the Bay of Bengal Coast, Bangladesh. Marine Pollution Bulletin, 175, 113274. https://doi.org/10.1016/j.marpolbul.2021.113274

Habibullah-Al-Mamun, Md., Ahmed, Md. K., Raknuzzaman, M., Islam, Md. S., Ali, M. M., Tokumura, M., & Masunaga, S. (2017). Occurrence and assessment of perfluoroalkyl acids (Pfaas) in commonly consumed seafood from the coastal area of Bangladesh. Marine Pollution Bulletin, 124(2), 775–785. https://doi.org/10.1016/j.marpolbul.2017.02.053

Hakanson, L. (1980). An ecological risk index for aquatic pollution control: A sedimentological approach. Water Research, 14(8), 975–1001. https://doi.org/10.1016/0043-1354(80)90143-8

Hasan, A. B., Kabir, S., Selim Reza, A. H. M., Zaman, M. N., Ahsan, M. A., Akbor, M. A., & Rashid, M. M. (2013). Trace metals pollution in seawater and groundwater in the ship breaking area of Sitakund Upazilla, Chittagong, Bangladesh. Marine Pollution Bulletin, 71(1–2), 317–324. https://doi.org/10.1016/j.marpolbul.2013.01.028

Hossain, M. M. M., & Islam, M. M. (2006). Ship breaking activities and its impact on the coastal zone of Chittagong, Bangladesh: Towards sustainable management. Advocacy & Publication Unit, Young Power in Social Action (YPSA). https://www.ypsa.org/publications/Impact.pdf

Lee, P.-K., Yu, S., Jeong, Y.-J., Seo, J., Choi, S., & Yoon, B.-Y. (2019). Source identification of arsenic contamination in agricultural soils surrounding a closed Cu smelter, South Korea. Chemosphere, 217, 183–194. https://doi.org/10.1016/j.chemosphere.2018.11.010

Mohan, S. V., Nithila, P., & Reddy, S. J. (1996). Estimation of heavy metals in drinking water and development of heavy metal pollution index. Journal of Environmental Science and Health. Part A: Environmental Science and Engineering and Toxicology, 31(2), 283–289. https://doi.org/10.1080/10934529609376357

Muller, G., 1969. Index of geoaccumulation in sediments of the Rhine River. GeoJournal 2, 108–118. 

Neşer, G., Kontas, A., Ünsalan, D., Altay, O., Darılmaz, E., Uluturhan, E., Küçüksezgin, F., Tekoğul, N., & Yercan, F. (2012). Polycyclic aromatic and aliphatic hydrocarbons pollution at the coast of Aliağa (Turkey) ship recycling zone. Marine Pollution Bulletin, 64(5), 1055–1059. https://doi.org/10.1016/j.marpolbul.2012.02.019

Pasha, M., Mahmood, A. H., Rahman, I., & Hasnat, A. (2012, May). Assessment of ship breaking and recycling industries in Bangladesh – An effective step towards the achievement of environmental sustainability. In International conference on agricultural, environmental and biologica. 

Pathfriend Tour Operator. Chittagong ship breaking yard. https://pathfriend-bd.com/explore_bd/chittagong-ship-breaking-yard/

Proshad, R., Islam, S., Tusher, T. R., Zhang, D., Khadka, S., Gao, J., & Kundu, S. (2021). Appraisal of heavy metal toxicity in surface water with human health risk by a novel approach: A study on an urban river in vicinity to industrial areas of Bangladesh. Toxin Reviews, 40(4), 803–819. https://doi.org/10.1080/15569543.2020.1780615

Reddy, M. S., Basha, S., Sravan Kumar, V. G., Joshi, H. V., & Ramachandraiah, G. (2004). Distribution, enrichment and accumulation of heavy metals in coastal sediments of Alang–Sosiya ship scrapping yard, India. Marine Pollution Bulletin, 48(11–12), 1055–1059. https://doi.org/10.1016/j.marpolbul.2003.12.011

Sadiq, M. (1992). Toxic metal chemistry in marine environments. Marcel Dekker.

Siddiquee, N. A., Parween, S., Quddus, M. M. A., & Barua, P. (2012). Heavy metal pollution in sediments at ship breaking area of Bangladesh. In V. Subramanian (Ed.), Coastal Environments: Focus on Asian Regions (pp. 78–87). Springer Netherlands. https://doi.org/10.1007/978-90-481-3002-3_6

​​Barua, P., Rahman, S.H., Molla, M.H., 2017. Heavy metals effluence in sediments and its impact on macrobenthos at shipbreaking area of Bangladesh. Asian Profile 45 (2), 167–180.

Dispersants and why they can be harmful to the environment

Dispersants are chemicals that are often used as a response during oil spills, to reduce the IFT (interfacial tension) of oil slicks on the water’s surface to allow the oils to disperse more quickly. Its subsequent diffusion and dilution by ocean currents make it more available for biodegradation, therefore decreasing its danger to coastal areas, aquatic animals, and birds (Fink, 2021; Seidel et al., 2016). The use of dispersants as a response to oil spills has been attractive, as they are able to treat a large amount of oil quickly, under various environmental conditions (Chen et al., 2021). An example is during the Deepwater Horizon oil spill when large quantities of the dispersant Corexit was used– both sprayed onto the surface slick, as well as through subsea injection into the broken wellhead under the surface (Jones et al., 2017). Figure 1 depicts the use of chemical dispersants during an oil spill.  

Figure 1: Use of Chemical Dispersants during a Subsurface Oil Spill. (Source: Government accountability office., 2021).

However, a growing literature has raised concerns about the use of dispersants such as Corexit. Firstly, there are concerns that the toxicity of oil that has been dispersed in the water column may be higher compared to oil that has not been dispersed (Lewis & Pryor, 2013; Vignier et al., 2016). This concern arises from the fact that the dispersant causes an increase in the oil’s surface-to-volume ratio, therefore increasing its bioavailability to aquatic organisms, while also retaining its phytotoxic properties (Frometa et al., 2017). Moreover, there has been apprehension about the potential inherent toxicity of dispersants, in which the long-term persistence of these dispersants may result in additional negative externalities to the environment that they were intended to safeguard (Goodbody-Gringley et al., 2013; White et al., 2014). Notably, a study by Rico-Martínez et al. (2013) found toxicity to B. manjavacas (marine zooplankton commonly used in ecotoxicological studies), to increase by 52 times, when the dispersant Corexit 9500A was mixed with crude oil. Additionally, in a recent review of knowledge of the toxicity of the dispersant Corexit 9500A by Stroski et al. (2019), they concluded that while Corexit 9500A dispersant has limited to no effect on higher-level organisms, it has significant negative impacts on certain lower trophic level organisms such as microzooplankton and small crustaceans, as well as on some larval form of higher trophic species. 

Possible solution moving forward: Sustainable dispersants? 

With regard to the second potential concern of dispersants being toxic, a possible solution moving forward is the switch to the use of sustainable dispersants. For this next section, I refer to a review of recent developments in new sustainable dispersants by Zhu et al. (2022). According to Zhu et al. (2022), sustainable dispersants are dispersants that are made out of environmentally friendly ingredients (e.g., food-grade chemical surfactants, biosurfactants, ionic liquids, and additives). Of the various sustainable dispersants that have been evaluated as dispersant ingredients (shown in Table 1), Lecithin and Tween 80, when used in combination, have been found to have a very high dispersant efficiency (89%), where it is able to reduce the interfacial tension between seawater and oil to 0.03-0.4 mN/m. Additionally, according to Owoseni et al. (2018), they are able to reduce the average oil droplet size to 7.81 mm. This is comparable to that of commercial dispersants (E.g. Corexit 9500A).

Table 1: Summary of evaluation of recent developments in sustainable dispersants. (Source: Zhu et al., 2022). 

These biosurfactant-based dispersants, as the biological equivalent of chemical alternatives, have the key environmental benefit of having a higher biodegradability (Zhu et al., 2022). For instance, Tween 80 and Tween 85 had a notably rapid rate of biodegradation, with their levels becoming undetectable after 4-8 days even in cold seawater environments (5°C). In contrast to Tween 80 and Tween 85, chemical surfactants have a significantly longer delay before they start to biodegrade, with reported half-lives of 20, 28, and 24 days in Corexit, Dasic, and Finasol, respectively (Brakstad et al., 2018). Additionally, biosurfactant-based dispersants have also been found to have lower than that of chemical surfactants (Zhu et al., 2022). 

However, there remain challenges. According to Zhu et al. (2022), low yield, and high production costs are the main obstacles barring the widespread adoption of such sustainable biosurfactant-based dispersants. Moving forward, one potential option is to consider using waste/by-products as substrates/raw materials for production. One suggestion has been to extract peptone from tuna fish waste, which can be used for the subsequent production of biosurfactants (Hu et al., 2021). 

Conclusion

Overall, sustainable dispersants, as a possible response to oil spills, provide a useful alternative that can potentially bring about lower ecological impacts. However, there is still an ongoing debate with regard to whether or not the dispersion of oil brings more or less negative externalities to the environment (Merlin et al., 2021; Prince, 2015). Therefore, more research still needs to be conducted in that area. Such research would inform policymakers’ response to future oil spills. 

References 

Brakstad, O. G., Størseth, T. R., Brunsvik, A., Bonaunet, K., & Faksness, L.-G. (2018). Biodegradation of oil spill dispersant surfactants in cold seawater. Chemosphere, 204, 290–293. https://doi.org/10.1016/j.chemosphere.2018.04.051

Chen, B., Lee, K., Merlin, F., Yang, M.,Ye, X., Zhang, B., & Zhu, Z. (2021). Ecological impact analysis of dispersants and dispersed oil: An overview. Journal of Environmental Informatics Letters, 5(2), 120-133. https://doi.org/10.3808/jeil.202100058

Fink, J. (2021). Oil spill treating agents. In Petroleum Engineer’s Guide to Oil Field Chemicals and Fluids (pp. 859–879). Elsevier. https://doi.org/10.1016/B978-0-323-85438-2.00019-0

Frometa, J., DeLorenzo, M. E., Pisarski, E. C., & Etnoyer, P. J. (2017). Toxicity of oil and dispersant on the deep water gorgonian octocoral Swiftia exserta, with implications for the effects of the Deepwater Horizon oil spill. Marine Pollution Bulletin, 122, 91–99. https://doi.org/10.1016/j.marpolbul.2017.06.009

Goodbody-Gringley, G., Wetzel, D. L., Gillon, D., Pulster, E., Miller, A., & Ritchie, K. B. (2013). Toxicity of deepwater horizon source oil and the chemical dispersant, corexit® 9500, to coral larvae. PLoS ONE, 8(1), e45574. https://doi.org/10.1371/journal.pone.0045574

Government Accountability Office. (2021). Offshore oil spills: Additional information is needed to better understand the environmental tradeoffs of using chemical dispersants (GAO-22-104153). https://www.gao.gov/products/gao-22-104153 

Hu, J., Luo, J., Zhu, Z., Chen, B., Ye, X., Zhu, P., & Zhang, B. (2021). Multi-scale biosurfactant production by bacillus subtilis using tuna fish waste as substrate. Catalysts, 11(4), 456. https://doi.org/10.3390/catal11040456

Jones, E. R., Martyniuk, C. J., Morris, J. M., Krasnec, M. O., & Griffitt, R. J. (2017). Exposure to Deepwater Horizon oil and Corexit 9500 at low concentrations induces transcriptional changes and alters immune transcriptional pathways in sheepshead minnows. Comparative Biochemistry and Physiology Part D: Genomics and Proteomics, 23, 8–16. https://doi.org/10.1016/j.cbd.2017.05.001

Lewis, M., & Pryor, R. (2013). Toxicities of oils, dispersants and dispersed oils to algae and aquatic plants: Review and database value to resource sustainability. Environmental Pollution, 180, 345–367. https://doi.org/10.1016/j.envpol.2013.05.001

Merlin, F., Zhu, Z., Yang, M., Chen, B., Lee, K., Boufadel, M. C., Isaacman, L., & Zhang, B. (2021). Dispersants as marine oil spill treating agents: A review on mesoscale tests and field trials. Environmental Systems Research, 10(1), 37. https://doi.org/10.1186/s40068-021-00241-5

Prince, R. C. (2015). Oil spill dispersants: Boon or bane? Environmental Science & Technology, 49(11), 6376–6384. https://doi.org/10.1021/acs.est.5b00961

Rico-Martínez, R., Snell, T. W., & Shearer, T. L. (2013). Synergistic toxicity of Macondo crude oil and dispersant Corexit 9500A® to the Brachionus plicatilis species complex (Rotifera). Environmental Pollution, 173, 5–10. https://doi.org/10.1016/j.envpol.2012.09.024

Seidel, M., Kleindienst, S., Dittmar, T., Joye, S. B., & Medeiros, P. M. (2016). Biodegradation of crude oil and dispersants in deep seawater from the Gulf of Mexico: Insights from ultra-high resolution mass spectrometry. Deep Sea Research Part II Topical Studies in Oceanography, 129, 108–118. https://doi.org/10.1016/j.dsr2.2015.05.012

Stroski, K. M., Tomy, G., & Palace, V. (2019). The current state of knowledge for toxicity of corexit EC9500A dispersant: A review. Critical Reviews in Environmental Science and Technology, 49(2), 81–103. https://doi.org/10.1080/10643389.2018.1532256

Vignier, J., Soudant, P., Chu, F. L. E., Morris, J. M., Carney, M. W., Lay, C. R., Krasnec, M. O., Robert, R., & Volety, A. K. (2016). Lethal and sub-lethal effects of Deepwater Horizon slick oil and dispersant on oyster (Crassostrea virginica) larvae. Marine Environmental Research, 120, 20–31. https://doi.org/10.1016/j.marenvres.2016.07.006

White, H. K., Lyons, S. L., Harrison, S. J., Findley, D. M., Liu, Y., & Kujawinski, E. B. (2014). Long-term persistence of dispersants following the deepwater horizon oil spill. Environmental Science & Technology Letters, 1(7), 295–299. https://doi.org/10.1021/ez500168r

Zhu, Z., Song, X., Cao, Y., Chen, B., Lee, K., & Zhang, B. (2022). Recent advancement in the development of new dispersants as oil spill treating agents. Current Opinion in Chemical Engineering, 36, 100770. https://doi.org/10.1016/j.coche.2021.100770

Every year, more than 10 million tonnes of plastic enter the world’s oceans annually (Jambeck et al. 2015). As of 2014, over 5 trillion counts of plastic, weighing over 260 thousand tonnes, float over our oceans (Erikson et al., 2014). Not only is this figure certainly significantly higher now, but most of the plastic in our oceans is also out of sight from the surface, with most (97%) of the plastic that ends up in our oceans being reported to be on the sea floor (Eunomia, 2016). These plastics can be broadly classified into 4 categories, based on their size– namely macroplastics, mesoplastics and microplastics (Thushari & Senevirathna, 2020) (Figure 1). In marine and coastal environments, the high salinity of seawater intensifies the degradation and fragmentation (by various physical, chemical and biological processes) of larger pieces of plastics into microplastics (plastics less than 5mm in diameter) (Browne et al., 2011; Wang et al., 2018). As such, microplastics are the most abundant form of MPP, and can be extensively found across all layers of the ocean (Thompson, 2015; Thushari & Senevirathna, 2020).

Figure 1: Classification of plastic litter based on their size. (Loganathan, 2022)

Negative Impacts of Marine Plastic Pollution (MPP) on the environment

I’m sure many of us are familiar with or have at least heard of the numerous adverse ecological impacts that plastic pollution can have on marine biodiversity, as well as on human health. Firstly, the ingestion and entanglement of macroplastic fragments pose significant risks for marine and coastal organisms. Gall and Thompson (2015) recorded that over 208 species have experienced problems related to the accidental ingestion of macroplastic fragments, while a further 243 species have been entangled by these fragments. While the ingestion and entanglement of plastics by marine organisms are not always lethal, they can result in many other sub-lethal effects, such as the loss of mobility, reduced food intake and decreased growth (Gall and Thomspon, 2015). Figure 2 highlights some of the effects on marine and coastal organisms, due to ingestion and entanglement. 

Figure 2: Effects of plastic ingestion and entanglement by marine and coastal organisms. a) Plastics ingestion by a blue shark; b) Attachment on plastic debris by Goose Barnacle; c)Partial cover of macroplastic pollutants on Rock Oyster; d)Entanglement of nestling in a synthetic plastic string. (Thushari & Senevirathna, 2020).

Similarly, being similar to the feeding matter of many organisms, microplastics are also often ingested by many marine organisms (Browne et al., 2007; Wright, 2013). Such microplastics are highly toxic, as not only do they contain toxic chemicals (e.g. Bisphenol-A, monomers, oligomers, flame retardants etc), but they also absorb surrounding persistent toxic chemical substances such as Persistent Organic Pollutants (POPs)– often by-products of industrial processes, that are resistant to biodegradation (e.g. dioxins and various industrial chemicals) (Thushari & Senevirathna, 2020). Such ingestion of microplastics often results in the chemical bioaccumulation of toxic chemicals in organisms throughout the food chain. The subsequent consumption of such seafood by humans poses significant health effects (Cole et al., 2013). 

Is the shipping industry a major contributor to marine plastic pollution? 

In the preceding section, we delved into the various adverse effects of MPP. However, as the focus of this blog is on the polluting impacts of the shipping industry, in the following section, I aim to investigate whether the shipping industry is a substantial contributor to MPP.

According to Annex V of the International Convention for the Prevention of Pollution from Ships (MARPOL) (Entered into force in 1978 and signed by 156 states, representing 99.42% of the world’s shipping tonnage), merchant ships are prohibited from disposing of any garbage into the sea, and instead, dispose it only at ports. Additionally, ships are also required to prepare and implement Garbage Management Plans (International Chamber of Shipping, n.d.). According to the International Chamber of Shipping (ICS), discharge from MPP from ships is “very rare”. 

However, based on a report published by Eunomia (2016), while they have indeed identified land-based coastal pollution to be the biggest source of MPP, contributing around 9 million tonnes per annum (Mtpa), at-sea sources still accounted for 1.75Mtpa, of which litter from shipping activities contributed to 0.60Mtpa. Land-based inland pollution contributes 0.5Mtpa and microplastics (<5mm) contribute to the remaining 0.95Mtpa. Figure 3 highlights the various sources of MPP, as well as their eventual sinks. 

Figure 3: Source and sinks of Marine Plastic Pollution (MPP). (Eunomia, 2016).

Where does MPP from the shipping industry originate from then? 

An insight into one source of MPP from the shipping industry– shipping container spills, is provided in a recent paper by Saliba et al. (2022). Citing the World Shipping Council, they highlight that an annual average of 1382 containers, equivalent to 13,820t of consumer packaged goods (CPG) are lost at sea yearly (World Shipping Council, 2020, as cited in Saliba et al, 2022). 

While this represents only a small percentage of the estimated 0.60Mtpa of MPP that is contributed by the shipping industry, MPP from shipping container spills is nonetheless a noteworthy source of MPP. This is especially so as Saliba et al. (2022) have, in their review of maritime governance in the North Sea, highlighted the inadequacy of current legal and policy instruments, as well as mechanisms, to hold MPP polluters liable for the environmental damage that they have caused by shipping container loss. 

The next section, using examples from the North Sea, highlight a few of the identified policy gaps, where current systems and processes in place at global and regional governance levels fail to hold polluters accountable for MPP. 

Global Level: The absence of the need to declare the loss of containers at sea

As identified by Saliba et al. (2022), under the International Convention for the Prevention of Pollution from Ships (MARPOL)– which is the main global convention covering the prevention of pollution of the marine environment by ships from operational or accidental causes– there is an absence of a compulsory system to report lost shipping containers at sea or to determine the total number of containers/goods lost. This has led to the lack of reporting of shipping container losses. 

An example is the Ever Laurel case in 1992, where when a shipping container vessel– The Ever Laurel, owned by the Evergreen Marine Corporation, and transporting children’s bath toys from Hong Kong to Washington– had over 29,000 floating plastic toys fall overboard into the Central Pacific Ocean (Ebbesmeyer et al., 2007). This has resulted in various MPPs (in the form of children’s bath toys) continuing to wash ashore along various coasts of the Pacific Ocean (as far as the British Isles), even many years later. However, as the spill was neither reported by the Ever Laurel nor witnessed by others, the identity and cause of the spill were only revealed many years later by journalists. 

Regional (European Union & North Sea): Absence of specific legislation to address MPP as a result of accidental container loss

The European Union has adopted several directives to ensure offences of MARPOL can be prosecutable under criminal law. The ‘Protection of the Environment through Criminal Law’ (Directive 2008/99/EC), mandates the prosecution of states for causing harm to the quality of water, animals, and plants (European Union, 2016). Additionally, the ‘Environmental Liability Directive’ (ELD) (DIrective 2004/35/CE), which adopts the Polluter Pays Principle, covers the prevention and mitigation of environmental damage caused by the discharge of hazardous and noxious substances (HNS) (The European Parliament and the Council of the European Union, 2004). 

However, Saliba et al. (2022) have, through interviews, identified some policy gaps that render these directives ineffective in dealing with MPP from shipping container losses. Firstly, plastic is excluded from the HNS list. Additionally, although the ELD mandates polluters to finance the restoration of damaged nature to its original state, it has been challenging to apply it in previous maritime oil spills, such as the Torrey Canyon and Amoco Cadiz incidents, due to insufficient baseline data of the conditions of the affected environment. Applying this to MPP in the context of container spills, it becomes challenging to hold responsible parties liable for the harm caused to nature and its ecosystem services. This is because states would need to demonstrate the extent of ecological damage caused by the plastic spill, based on baseline conditions. 

The exclusion of MPP is not limited to the ELD. Another example is In the main regional agreement present in the North Sea to unify efforts the pollution– The Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR Convention). While the OSPAR convention requires states to ensure incidents of container spills are reported, it does not consider MPP to be damaging to the environment and is not listed as a noxious pollutant. 

Conclusion

In conclusion, while MPP has adverse ecological impacts on marine biodiversity, as well as on human health, Saliba et al. (2022) have, in their review of marine governance at various levels, found a lack of systems and processes in place to hold polluters of MPP by shipping container loss accountable. This, therefore, brings to light, the difficulty in enforcing compensation for the damage that MPPs have on the ecosystem. Ultimately, a concerted effort is needed by all stakeholders (international organisations, governments, shipping industry),  to address the issue of MPP by shipping container loss. This can start with MARPOL mandating the need to report all shipping container losses. 

References

Browne, M. A., Crump, P., Niven, S. J., Teuten, E., Tonkin, A., Galloway, T., & Thompson, R. (2011). Accumulation of microplastic on shorelines woldwide: Sources and sinks. Environmental Science & Technology, 45(21), 9175–9179. https://doi.org/10.1021/es201811s

Browne, M. A., Galloway, T., & Thompson, R. (2007). Microplastic-an emerging contaminant of potential concern?: Learned Discourses. Integrated Environmental Assessment and Management, 3(4), 559–561. https://doi.org/10.1002/ieam.5630030412

Cole, M., Lindeque, P., Fileman, E., Halsband, C., Goodhead, R., Moger, J., & Galloway, T. S. (2013). Microplastic ingestion by zooplankton. Environmental Science & Technology, 47(12), 6646–6655. https://doi.org/10.1021/es400663f

Ebbesmeyer, C. C., Ingraham, W. J., Royer, T. C., & Grosch, C. E. (2007). Tub toys orbit the pacific subarctic gyre. Eos, Transactions American Geophysical Union, 88(1), 1. https://doi.org/10.1029/2007EO010001

Eriksen, M., Lebreton, L. C. M., Carson, H. S., Thiel, M., Moore, C. J., Borerro, J. C., Galgani, F., Ryan, P. G., & Reisser, J. (2014). Plastic pollution in the world’s oceans: More than 5 trillion plastic pieces weighing over 250,000 tons afloat at sea. PLoS ONE, 9(12), e111913. https://doi.org/10.1371/journal.pone.0111913

Eunomia. (2016). Plastics in the marine environment. https://www.eunomia.co.uk/reports-tools/plastics-in-the-marine-environment/

European Union. (2016). Report for European Commission DG environment. Study to support the development of measures to combat a range of marine litter sources incentivising waste disposal at ports. http://ec.europa.eu/environment/marine/good-environmental-status/descriptor-10/pdf/MSFDMeasurestoCombatMarineLitter.pdf

Gall, S. C., & Thompson, R. C. (2015). The impact of debris on marine life. Marine Pollution Bulletin, 92(1–2), 170–179. https://doi.org/10.1016/j.marpolbul.2014.12.041

International Chamber of Shipping. (n.d.). Action on plastics. https://www.ics-shipping.org/current-issue/action-on-plastics/

Jambeck, J. R., Geyer, R., Wilcox, C., Siegler, T. R., Perryman, M., Andrady, A., Narayan, R., & Law, K. L. (2015). Plastic waste inputs from land into the ocean. Science, 347(6223), 768–771. https://doi.org/10.1126/science.1260352

Loganathan, Y. (2022). A review on microplastics – an indelible ubiquitous pollutant. Biointerface Research in Applied Chemistry, 13(2), 126. https://doi.org/10.33263/BRIAC132.126

Saliba, M., Frantzi, S., & Van Beukering, P. (2022). Shipping spills and plastic pollution: A review of maritime governance in the North Sea. Marine Pollution Bulletin, 181, 113939. https://doi.org/10.1016/j.marpolbul.2022.113939

The European Parliament and the Council of the European Union. (2004). Directive 2004/ 35/CE on Environmental Liability With Regard to the Prevention and Remedying of Environmental Damage. 

Thompson, R. C. (2015). Microplastics in the marine environment: Sources, consequences and solutions. In M. Bergmann, L. Gutow, & M. Klages (Eds.), Marine Anthropogenic Litter (pp. 185–200). Springer International Publishing. https://doi.org/10.1007/978-3-319-16510-3_7

Thushari, G. G. N., & Senevirathna, J. D. M. (2020). Plastic pollution in the marine environment. Heliyon, 6(8), e04709. https://doi.org/10.1016/j.heliyon.2020.e04709

Wang, J., Zheng, L., & Li, J. (2018). A critical review on the sources and instruments of marine microplastics and prospects on the relevant management in China. Waste Management & Research: The Journal for a Sustainable Circular Economy, 36(10), 898–911. https://doi.org/10.1177/0734242X18793504

Wright, S. L., Thompson, R. C., & Galloway, T. S. (2013). The physical impacts of microplastics on marine organisms: A review. Environmental Pollution, 178, 483–492. https://doi.org/10.1016/j.envpol.2013.02.031

Polar Shipping Routes

Over the past few decades, the Arctic Ocean has experienced rising temperatures and accelerated melting of the Arctic ice cap (Overland et al., 2019). Such accelerated melting has seen renewed interest in the possibility of an ‘open polar sea’ (Robinson, 2007). This is good news for the shipping industry, as should the Arctic ocean be traversable, it can potentially shorten shipping distances between Asia and Europe by 30 to 50%, and reduce transit time by 14 to 20 days (Bennett et al., 2020; Gunnarsson & Moe, 2021). Three plausible shipping routes across the Arctic have been brought forward, as seen in the Figure below (Figure 1). This includes the Northern Sea Route (shown in pink), the Northwest Passage (shown in blue), and the Transpolar Sea Route (shown in purple). Currently, of these three routes, the Northern Sea Route, has the highest potential of becoming a traversable polar route in the future, as it has already experienced periods in summer where it has been ‘ice-free’ (Staalesen, 2019). However, as the route traverses along the coast of Russia, it presents significant geopolitical issues, which present challenges to it being widely used as an international shipping route (Bennett et al., 2020). 

Figure 1: Arctic shipping routes. The Northern Sea Route is shown in pink, Transpolar Sea Route in purple, and the Northwest passage in blue.

However, a recent paper published by Lynch et al. (2022) appears to indicate further ‘good news’ for the shipping industry. In their study, they have modelled the probability of Arctic navigability (period of 32 days) for routes outside of Russian territorial waters for the period of 2015 to 2065. This was done using projections from 14 CMIP models across four scenarios (SSP1-2.6; SSP2-4.5; SSP3-7.0 and SSP5-8.5). Figure 2 below highlights their results. Notably, it suggests that from around 2050 onwards, under SSP2-4.5, SSP3-7.0 and SSP5-8.5, there is an approximate 50% probability that such routes would be navigatable. 

This is especially so under the SSP5-8.5 (very high GHG emissions scenario), where Lynch et al. (2022) note the increase in the viability of an open-water season for both the Transpolar Route and the Northwest Passage. This is shown in Figure 3, which depicts the frequency of models’ detection of an open-water navigable route from 2015- 2065 under the SSP5-8.5 (very high GHG emissions) scenario. The Transpolar Route is shown in Yellow, while the Northwest Passage is shown in red.

Figure 2: Projections from 14 CMIP models across four scenarios of the probability of Arctic navigability for 32 d (including shoulder periods) outside Russian territorial waters over the period 2015 to 2065, under four SSP scenarios (SSP1-2.6; SSP2-4.5; SSP3-7.0 and SSP5-8.5). (Lynch et al., 2022).

Figure 3: Spatial distribution of open-water navigable routes over the period 2015 to 2065 for the SSP5-8.5 scenario, expressed as a frequency of route detection per unit time. The transpolar route is indicated in yellow, the Northwest passage in red, and the Northern Sea routes in orange. (Lynch et al., 2022).

With the potential use of such routes as shipping routes, there is a need to think about the possible negative environmental impacts as a result of the pollutive impacts of the shipping industry. As explored in the previous blogs, these include (but are not limited to), the increase in air pollutants (NOx, SO2, black carbon); noise pollution; the introduction of invasive species and the negative impacts related to blige dumping (Blair et al., 2016; Brussaard et al., 2016; Erbe et al., 2019; Casas-Monroy et al., 2014; Couletti et al., 2006; Erying et al., 2010; McCarthy et al., 1994; Viana et al., 2014). For instance, should no measures be put in place, under business as usual (BAU) conditions, a study by Winther et al. (2014) predicts that by 2050, black carbon emissions will increase by 80%, while sulphur dioxide will increase by 1000%. 

This view is echoed by the lead author of the study, Amanda Lynch, where in an interview, she highlighted the need to “start thinking critically about the legal, environmental and geopolitical implications” (ScienceDaily, 2022). 

The Polar Code: What is it? 

In addressing the future operation of ships in the Arctic, there currently exists one key set of international regulations, released by the International Maritime Organisation (IMO), known as the Polar Code (International Code for Ships Operating in Polar Water). Entered into force in 2017, the purpose of the code is to provide safety and environmental standards for ships operating in polar regions (IMO, n.d.). It ensures that ships operating in the polar regions do so safely and with minimal impact on the environment (Liu, 2016). Figure 4 shows illustrate the various environmental requirements that ships sailing in the Arctic ocean have to adhere to. The following highlights some of the key points of the Polar Code, in preventing pollution: 

1. The prohibition of the carriage and use of heavy fuel oil (fuel oil having a density at 15°C higher than 900kg/m3. 
2. Prohibition of the discharge of any oil or oily mixtures, noxious liquid substances, sewage (unless treated) and garbage. 

Figure 4: Environmental requirements of the Polar Code. (IMO, n.d.).

The Polar Code: Is it sufficient? 

A cursory analysis of the Polar Code suggests that it is indeed effective in limiting and reducing future vessel-source pollution. By extension, we can therefore consider it sufficient in protecting the Arctic environment, by preventing and reducing future pollutive effects of the shipping industry (Explored in previous blogs). However, there are several main limitations to the Polar Code. Firstly, the Polar Code remains voluntary among countries. As such, the above environmental regulations, while stated in the Polar Code, are not being enforced by any law agency. This severely limits its effectiveness (Kauffman, 2019). Next, Chapter 3 of Part II-A, ‘Prevention of Pollutions by Harmful Substances Carried by Sea in Packaged Form’, has been left blank. This hints that further improvements to the code are also needed in the future. Lastly, the Polar Code also includes no limits or targets on greenhouse gas emissions by ships in the Arctic sea. This highlights the lack of focus on mitigating future climate change (Kauffman, 2019). 

Conclusion

With the increasing likelihood of future regular use of new polar routes (Lynch et al., 2022), there is a critical need to set in place strict environmental regulations, to prevent and limit the pollutive effects of shipping activities. While a mandatory Polar Code can help limit many of the impacts by enforcing various environmental standards, its current voluntary nature severely limits its effectiveness. Therefore, moving forward, the key aim for the IMO is to first get the support to ratify and subsequently enforce the environmental regulations stated in the Polar Code by member states of the Arctic council. Additionally, further limits on greenhouse gas emissions should be set, towards mitigating and preventing future climate change. 

References: 

Bennett, M. M., Stephenson, S. R., Yang, K., Bravo, M. T., & De Jonghe, B. (2020). The opening of the Transpolar Sea Route: Logistical, geopolitical, environmental, and socioeconomic impacts. Marine Policy, 121, 104178. https://doi.org/10.1016/j.marpol.2020.104178

Blair, H. B., Merchant, N. D., Friedlaender, A. S., Wiley, D. N., & Parks, S. E. (2016). Evidence for ship noise impacts on humpback whale foraging behaviour. Biology Letters, 12(8), 20160005. https://doi.org/10.1098/rsbl.2016.0005

Brussaard, C. P. D., Peperzak, L., Beggah, S., Wick, L. Y., Wuerz, B., Weber, J., Samuel Arey, J., Van Der Burg, B., Jonas, A., Huisman, J., & Van Der Meer, J. R. (2016). Immediate ecotoxicological effects of short-lived oil spills on marine biota. Nature Communications, 7(1), 11206. https://doi.org/10.1038/ncomms11206

Casas-Monroy, O., Linley, R.D., Adams, J.K., Chan, F.T., Drake, D.A.R., & Bailey, S.A. (2014). National risk assessment for introduction of aquatic nonindigenous species to Canada by ballast water. Canadian Science Advisory Secretariat. https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/352598.pdf

Colautti, R. I., Bailey, S. A., van Overdijk, C. D. A., Amundsen, K., & MacIsaac, H. J. (2006). Characterised and projected costs of nonindigenous species in canada. Biological Invasions, 8(1), 45–59. https://doi.org/10.1007/s10530-005-0236-y

Erbe, C., Marley, S. A., Schoeman, R. P., Smith, J. N., Trigg, L. E., & Embling, C. B. (2019). The effects of ship noise on marine mammals—A review. Frontiers in Marine Science, 6, 606. https://doi.org/10.3389/fmars.2019.00606

Eyring, V., Isaksen, I. S. A., Berntsen, T., Collins, W. J., Corbett, J. J., Endresen, O., Grainger, R. G., Moldanova, J., Schlager, H., & Stevenson, D. S. (2010). Transport impacts on atmosphere and climate: Shipping. Atmospheric Environment, 44(37), 4735–4771. https://doi.org/10.1016/j.atmosenv.2009.04.059

Gunnarsson, B., & Moe, A. (2021). Ten years of international shipping on the northern sea route: Trends and challenges. Arctic Review on Law and Politics, 12(0), 4. https://doi.org/10.23865/arctic.v12.2614

International Maritime Organisation (IMO). (n.d.). Shipping in polar waters: International code for ships operating in polar waters (Polar Code). https://www.imo.org/en/MediaCentre/HotTopics/Pages/polar-default.aspx

Kauffman, R. (2019, June 27). An analysis of the Polar Code. The Henry M.Jackson School of International Studies- University of Washington. https://jsis.washington.edu/news/an-analysis-of-the-polar-code/

Liu, N. (2016). Can the Polar Code save the Arctic. American Society of International Law, 20(7). https://www.asil.org/insights/volume/20/issue/7/can-polar-code-save-arctic#:~:text=Is%20the%20Polar%20Code%20Sufficient,for%20shipping%20in%20the%20Arctic

Lynch, A. H., Norchi, C. H., & Li, X. (2022). The interaction of ice and law in Arctic marine accessibility. Proceedings of the National Academy of Sciences, 119(26), e2202720119. https://doi.org/10.1073/pnas.2202720119

McCarthy, S. A., & Khambaty, F. M. (1994). International dissemination of epidemic Vibrio cholerae by cargo ship ballast and other nonpotable waters. Applied and Environmental Microbiology, 60(7), 2597–2601. https://doi.org/10.1128/aem.60.7.2597-2601.1994

Overland, J., Dunlea, E., Box, J. E., Corell, R., Forsius, M., Kattsov, V., Olsen, M. S., Pawlak, J., Reiersen, L.-O., & Wang, M. (2019). The urgency of Arctic change. Polar Science, 21, 6–13. https://doi.org/10.1016/j.polar.2018.11.008

Robinson, M.F. Reconsidering the theory of the open polar sea, in: K.R. Benson, H.M. Rozwadowski. In K.R. Benson., H.M. Rozwadowski. (Eds.), Extrem. Oceanogr. Adventure poles (pp. 15-29). Science History Publications. 

ScienceDaily. (2022, June 20). Melting Arctic ice could transform international shipping routes, study finds. https://www.sciencedaily.com/releases/2022/06/220620152119.htm

Staalesen, A. (2019, August 28). There is no ice left on Northern Sea Route. The Barents Observer. https://thebarentsobserver.com/en/arctic/2019/08/there-no-ice-left-russias-northern-sea-route

Viana, M., Hammingh, P., Colette, A., Querol, X., Degraeuwe, B., Vlieger, I. de, & van Aardenne, J. (2014). Impact of maritime transport emissions on coastal air quality in Europe. Atmospheric Environment, 90, 96–105. https://doi.org/10.1016/j.atmosenv.2014.03.046

Winther, M., Christensen, J. H., Plejdrup, M. S., Ravn, E. S., Eriksson, Ó. F., & Kristensen, H. O. (2014). Emission inventories for ships in the arctic based on satellite sampled AIS data. Atmospheric Environment, 91, 1–14. https://doi.org/10.1016/j.atmosenv.2014.03.006

As explored in Blog 3, growing scientific evidence has linked underwater radiated noise (URN)– an incidental product of shipping activities, to detrimental effects on marine mammals and organisms (Di Iorio & Clark, 2010; McCauley et al., 2017; Williams et al., 2015). Figure 1 shows the typical sources of URN from a shipping vessel. Unless there is a coordinated effort among governments, regulatory bodies, and ship manufacturers, the growing number and size of commercial vessels in our oceans will result in a continued increase in underwater noise pollution in the upcoming decades (Kaplan and Solomon, 2016). Therefore, this blog post will examine several key technological and policy options to reduce URN pollution.

Figure 1: Sources of Underwater radiated noise from a typical marine vessel (Smith & Rigby, 2022).

Reducing URN through technological solutions

In a review of noise reduction methods technology, Smith & Rigby (2022) have concluded that there exist numerous technological solutions have reached a high level of development, that can potentially be broadly implemented in the industry without necessitating further extensive research. Examples include passive vibration isolation mounts, vortex generators and an improved hull form design. The below table summarises several key technologies explored by Smith & Rigby (2022), that have high technology readiness levels (TRL). 

Table 1: Description of maturity of technological solutions to reduce URN, and their estimated Technology Readiness Level (TRL). (extracted from Smith & Rigby, 2022). 

Low uptake of such technological solutions

However, despite such technological solutions being available to reduce URN pollution at the source, they have argued their uptake by the industry is still very low (Smith & Rigby, 2022). Such a view is also adopted by other researchers (Chou, 2020; Merchant, 2019). 

In explaining this low uptake, the following reasons have been given by several authors: 

1. The lack of legal regulation denoting noise limits, or an economic incentive for commercial ship operators to reduce their noise pollution, or to adopt noise-reducing measures (Merchant, 2019).   
2. As acoustic trials are seldom conducted in the shipping industry, there is a lack of sufficient quantitative research evidence in two key areas: 
   1. URN levels produced by various shipping vessels under different operating conditions (Smith & Rigby, 2022). 
   2. Reduction of the noise pollution of shipping vessels after the adoption of specific technological solutions (Smith & Rigby, 2022). 

The challenge in designing policies to reduce noise pollution

Referring to the first point of the lack of international regulation in place to reduce shipping noise pollution at the source, a review of international policies, recommendations, actions and mitigation efforts regarding anthropogenic underwater noise by Chou et al. (2020) have confirmed that while many inter-governmental, government and academic bodies have highlighted the prevalent issue of noise pollution by the shipping industry, underwater noise is still not regulated. 

For instance, the International Maritime Organisation (IMO) has, in 2014, published the  “Guidelines for the reduction of underwater noise from commercial shipping to address adverse impacts on marine life” (IMO, 2014). This document detailed various technological solutions and good practices for shipping vessels to reduce their noise levels. However, it did not include any hard limits or regulations. This is unlike IMO’s regulation of sulphur in 2020, where it enforced a limit of the presence of sulphur in ships’ fuel oil to 0.50%, in a bid to reduce the release of sulphur dioxide into the air (Brynolf et al., 2014; Gilbert et al., 2018).  Furthermore, URN noise pollution is also not included in IMO’s International Convention for the Prevention of Pollution from Ships (MARPOL). 

This lack of such international regulation and policies is related to reason 2, where Merchant (2019) argues that the lack of quantitative data denoting the environmental benefit gained by reducing URN levels, has rendered it difficult for decision-makers to justify the economic cost incurred by implementing quieting solutions. Similarly, for many governments, unilaterally adopting assertive measures (e.g. setting maximum noise output levels), would serve to be a disincentive for shipping companies to use their ports (Merchant, 2019). 

However, the lack of sufficient research has not stopped some countries from taking a precautionary approach to dealing with the issue of URN noise pollution (Chou et al., 2021). For example, the Port of Vancouver, through its EcoAction program has taken an incentive-driven policy approach that aims to reduce URN noise pollution by providing lowered harbour rates for commercial vessels that adopt noise reduction technologies (portvancouver, n.d.). However, such incentive-driven policy approaches remain few (Smith & Rigby, 2022).

Moving forward

Moving forward, given the challenges of governments unilaterally adopting regulatory interventions, an internationally coordinated approach would be more effective in reducing global URN noise pollution (Merchant, 2019). Merchant (2019) offers some suggestions, which include setting requirements for new vessels to adopt ship-quieting technologies, while also developing policies to target reducing the noise output of the noisiest existing vessels. 

To aid this, key quantitative research in the above key areas needs to be done. Additionally, it is also necessary to conduct studies over extended periods to determine the effects of noise reduction on surrounding marine wildlife (Chou et al., 2021). It is only when it has been quantitatively evidenced that the reduction of noise through various noise abatement strategies (e.g. adopting noise-reducing technologies, lowering speeds etc) can lead to benefits for surrounding marine organisms, can more efficient and effective command-and-control approaches (mandatory controls to reduce URN noise pollution) be more readily devised and adopted globally (Merchant, 2019). 

References: 

Brynolf, S., Fridell, E., & Andersson, K. (2014). Environmental assessment of marine fuels: Liquefied natural gas, liquefied biogas, methanol and bio-methanol. Journal of Cleaner Production, 74, 86–95. https://doi.org/10.1016/j.jclepro.2014.03.052

Chou, E., Southall, B. L., Robards, M., & Rosenbaum, H. C. (2021). International policy, recommendations, actions and mitigation efforts of anthropogenic underwater noise. Ocean & Coastal Management, 202, 105427. https://doi.org/10.1016/j.ocecoaman.2020.105427

Di Iorio, L., & Clark, C. W. (2010). Exposure to seismic survey alters blue whale acoustic communication. Biology Letters, 6(1), 51–54. https://doi.org/10.1098/rsbl.2009.0651

Gilbert, P., Walsh, C., Traut, M., Kesieme, U., Pazouki, K., & Murphy, A. (2018). Assessment of full life-cycle air emissions of alternative shipping fuels. Journal of Cleaner Production, 172, 855–866. https://doi.org/10.1016/j.jclepro.2017.10.165

International Maritime Organisation (IMO). (2014). Guidelines for the reduction of underwater noise from commercial shipping to address adverse impacts on marine life. https://wwwcdn.imo.org/localresources/en/MediaCentre/HotTopics/Documents/833%20Guidance%20on%20reducing%20underwater%20noise%20from%20commercial%20shipping,.pdf

Kaplan, M. B., & Solomon, S. (2016). A coming boom in commercial shipping? The potential for rapid growth of noise from commercial ships by 2030. Marine Policy, 73, 119–121. https://doi.org/10.1016/j.marpol.2016.07.024

McCauley, R. D., Day, R. D., Swadling, K. M., Fitzgibbon, Q. P., Watson, R. A., & Semmens, J. M. (2017). Widely used marine seismic survey air gun operations negatively impact zooplankton. Nature Ecology & Evolution, 1(7), 0195. https://doi.org/10.1038/s41559-017-0195

Merchant, N. D. (2019). Underwater noise abatement: Economic factors and policy options. Environmental Science & Policy, 92, 116–123. https://doi.org/10.1016/j.envsci.2018.11.014

Portvancouver. (n.d.). Ecoaction program. https://www.portvancouver.com/environmental-protection-at-the-port-of-vancouver/climate-action-at-the-port-of-vancouver/ecoaction-program/

Smith, T. A., & Rigby, J. (2022). Underwater radiated noise from marine vessels: A review of noise reduction methods and technology. Ocean Engineering, 266, 112863. https://doi.org/10.1016/j.oceaneng.2022.112863

Williams, R., Wright, A. J., Ashe, E., Blight, L. K., Bruintjes, R., Canessa, R., Clark, C. W., Cullis-Suzuki, S., Dakin, D. T., Erbe, C., Hammond, P. S., Merchant, N. D., O’Hara, P. D., Purser, J., Radford, A. N., Simpson, S. D., Thomas, L., & Wale, M. A. (2015). Impacts of anthropogenic noise on marine life: Publication patterns, new discoveries, and future directions in research and management. Ocean & Coastal Management, 115, 17–24. https://doi.org/10.1016/j.ocecoaman.2015.05.021

The need for alternative fuel 

As previously mentioned in Blog 1, shipping is considered the most efficient transport mode of freight transport (on a tonne/km basis). It consumes less fuel and has a lower environmental footprint when compared to other transport modes (IMO, 2009). However, this does not discount the fact that the global shipping industry is still responsible for emitting a significant amount of carbon dioxide into the atmosphere. In 2018, according to the International Maritime Organisation’s 2020 greenhouse gas study, global shipping activity has been found accountable for emitting roughly 1.05 billion tons of carbon dioxide into the atmosphere, contributing approximately 2.9% of total global CO2 emissions (IMO, 2020). In addition to CO2 emissions, shipping is also a major contributor to sulfur dioxide (SO2) and nitrogen oxides (NOx) (Geels et al., 2021; Gong et al., 2018; Viana et al., 2014). 

This is largely in part due to the prevalent use of low-grade heavy fuel oil, or ‘Bunker oil’– produced from the blending of residual oil and refinery intermediates, in the shipping industry (Uhler et al., 2016). Figure 1 highlights the trend of the fuel mix of various vessel types (HFO= Heavy fuel oil; MDO/MGO= Marine diesel/Marine gas oil; LSH= Low sulfur heavy fuel oil; LNG= Liquefied natural gas). Based on this figure (published in 2019), it is apparent that a large percentage of shipping vessels still heavily rely on the use of heavy fuel oil (Schnurr & Walker, 2019). The combustion of such Bunker oil is the main culprit for the release of CO2, SO2, NOx, and other pollutive substances into the atmosphere (Schnurr & Walker, 2019). 

Figure 1: Fuel mix for various vessel types (HFO = Heavy Fuel Oil; MDO/MGO = Marine Diesel/Gas Oil; LSHFO = Low Sulfur Heavy Fuel Oil; LNG = Liquefied Natural Gas). (Schnurr & Walker, 2019).

In response, the International maritime organisation (IMO), through an update of the  International Convention for the Prevention of Pollution from Ships (MARPOL), mandated vessels to reduce their fuel sulphur content to 0.1% in Emissions Control Areas, and 0.5% globally from 2020 (Brynolf et al., 2014; Gilbert et al., 2018). Furthermore, in line with the Paris Agreement, IMO has, in 2021, set out its objective of a 40% reduction of CO2 emissions per transport work, when compared to 2008 levels by 2030, as well as a 50% reduction of total annual greenhouse gas emissions, when compared to 2008 levels by 2050 (IMO, 2021). As such, the combined pressure of reducing SO2 and NOx in the short term, and the longer need of reducing greenhouse gas emissions, has prompted the shipping industry to find alternative sources of fuel. Some examples include Liquefied Natural Gas (LNG), methanol, and hydrogen (Brynolf et al., 2014). These fuels offer a cleaner alternative to Bunker oil, given that they contribute to lower emissions. 

However, several authors have argued the need to critically consider the entire product life cycle of alternative fuels (Production → Storage → Transport → End Use), before determining whether or not a particular fuel can deliver meaningful emissions savings for the entire shipping industry (Atilhan et al., 2021; Gilbert et al., 2018). Additionally, there is a need to take into account various technological, economic and social factors, such as safety (Gilbert et al., 2018). Hence, in this week’s post, we would be critically assessing the potential one such alternative fuel, hydrogen. 

Hydrogen as an alternative fuel

Hydrogen has been considered one of the most promising potential alternatives to the replacement of heavy fuel oil, primarily because its combustion releases zero carbon emissions, producing only water in its process. This has the potential to significantly lower the amount of carbon dioxide emissions that are released into the environment (Jessop et al., 1995; Dorner et al., 2010). 

Hydrogen can be categorized based on the production method and raw materials used into grey, blue and green hydrogen. Grey hydrogen is formed through the reforming of fossil fuels. This is currently the most popular method in which liquid hydrogen fuel is obtained (~95%), often through the process of steam reforming of natural or shale gas (Martı́nez et al., 2014). The production of blue hydrogen is similar, except that in the reforming of fossil fuels, carbon emissions are captured, stored or further utilised (Noureldin et al., 2015). Lastly, liquid hydrogen fuel can be considered green when it is produced by utilizing renewable energy sources and feedstocks throughout (Atilhan et al., 2021). Figure 2 depicts the hydrogen fuel production chain and lifecycle. 

Figure 2: Production life cycle of various forms of liquid hydrogen. (Altihan et al., 2021).

Can all forms of hydrogen be considered clean? 

However, while the combustion of liquid hydrogen does not emit any carbon dioxide, it does not mean that no GHG emissions are released in the other stages of its lifecycle. Critical analysis of the production of various types of liquid hydrogen (broadly classified into grey, blue and green) by Atilhan et al. (2020), have found that while grey liquid hydrogen is the most cost-effective (costing approximately ¼ of the cost currently required to produce green hydrogen), its total carbon footprint has been measured to be between 120-155g CO2 eq per megajoule of energy contained in the fuel. This exceeds that of the production of heavy fuel oil, at about 90g eq/MJ (Brynolf et al., 2014). Next, depending on the carbon capture or other technology used, blue liquid hydrogen, while produced in similar ways as grey liquid hydrogen, has a lower carbon footprint of between 40-90g eq/MJ. Lastly, while most expensive, green liquid hydrogen, when obtained through the liquefaction of hydrogen by renewable sources such as wind and solar energy, can have a carbon footprint as low as 4.6 and 11.7g eq/MJ respectively. Figure 3 below compares the greenhouse gas emission released by various types of hydrogen production. It can be seen that the method of hydrogen production largely affects the environmental footprint of the hydrogen fuel produced. 

Figure 3: Greenhouse gas emissions data comparison (g CO2e/MJ fuel) for LH2 to grey, blue and green H2 production. (Altihan et al., 2021).

Techno-economic evaluation of liquefied hydrogen

As explored above, green hydrogen has the lowest overall carbon footprint, making it a promising replacement fuel for the shipping industry. However, in its production, large amounts of electricity (generated from renewable sources such as solar or wind power) are required for electrolysis, where water molecules are split into hydrogen and oxygen. The large amount of energy required for electrolysis significantly increases the cost of production (4 times more than the production of grey hydrogen), hindering the wide-scale implementation of this technique (Altihan et al., 2021). Figure 4 compares the cost of producing grey hydrogen, with current green hydrogen production methods. 

Figure 4: Comparing the cost of producing grey liquid hydrogen (LH2), with various green liquid hydrogen producing methods. (Altihan et al., 2021).

Safety evaluation of liquefied hydrogen

Next, according to US National Fire Protection Association (NFPA) 704 standards that categorize various fuels from 0-4 to determine its risk level, liquid hydrogen has been assessed to have high flammability, assigned a severity of 4 (Table 1). Furthermore, the high energy intensity of hydrogen, demonstrated by its lower heating value (LHV) of 120 MJ/kg (2.8 times the LHV of Heavy fuel oil), as well as its wider flammable limit range and lower boiling and flash temperature, is expected to make hydrogen an inherently more dangerous fuel (Table 2). Furthermore, the storage of liquid hydrogen requires cryogenic conditions as the liquefaction temperature of liquid hydrogen is -253°C (Table 3). This creates multiple hazards as exposure to skin can cause cold burns, while any leakage can potentially create an explosive mixture of liquefied air and hydrogen (Edelia et al., 2018). 

Table 1: Comparison of fuel hazardous characteristics via the US National Fire Protection Association (NFPA) 704. (Altihan et al., 2021).

Table 2: Comparison of the potential of explosion and fire. (Altihan et al., 2021).

Table 3: Comparison of different marine fuels. (Altihan et al., 2021).

Other logistical and infrastructural concerns pertaining to the use of liquid hydrogen

As seen from the table above, liquid hydrogen has a significantly lower volumetric density when compared to liquid natural gas (LNG) (Table 3). For instance, compared to LNG, liquid hydrogen requires 2.8 times the volume to store. This results in infrastructural and logistical concerns, as this can result in the reduction of cargo space available, to create room for the fuel (Atlihan et al., 2021). 

Moving forward 

However, there is still potential for green hydrogen to become a replacement fuel for the shipping industry in the future. With the advancement of technical capabilities in green energy production, the cost of green renewable energy production is projected to lower by 70% in the next decade. This would render the uptake and production of green hydrogen more economically feasible (Atlihan et al., 2021). To facilitate the commercial adoption of green hydrogen, Atlihan et al. (2021) further argue that codes and standards of hydrogen bunkering and onboard storage need to be well-defined before widespread implementation can occur, in order to ensure safety and public acceptance. 

In conclusion, the shipping industry currently runs on highly pollutive ‘Bunker oil’. There is therefore a need for the shipping industry to transit towards cleaner sources of fuel. However, when considering the adoption of alternative fuels, there is a need to consider the environmental footprint not only when it is in use, but also its footprint along all stages of its production life cycle. Furthermore, various technological, economic and social factors regarding the production and use of the fuel, will also need to be considered. 

References

Atilhan, S., Park, S., El-Halwagi, M. M., Atilhan, M., Moore, M., & Nielsen, R. B. (2021). Green hydrogen as an alternative fuel for the shipping industry. Current Opinion in Chemical Engineering, 31, 100668. https://doi.org/10.1016/j.coche.2020.100668

Brynolf, S., Fridell, E., & Andersson, K. (2014). Environmental assessment of marine fuels: Liquefied natural gas, liquefied biogas, methanol and bio-methanol. Journal of Cleaner Production, 74, 86–95. https://doi.org/10.1016/j.jclepro.2014.03.052

Dorner, R. W., Hardy, D. R., Williams, F. W., & Willauer, H. D. (2010). Heterogeneous catalytic CO2 conversion to value-added hydrocarbons. Energy & Environmental Science, 3(7), 884. https://doi.org/10.1039/c001514h

Edelia, E. M., Winkler, R., Sengupta, D., El-Halwagi, M. M., & Mannan, M. S. (2018). A computational fluid dynamics evaluation of unconfined hydrogen explosions in high pressure applications. International Journal of Hydrogen Energy, 43(33), 16411–16420. https://doi.org/10.1016/j.ijhydene.2018.06.108

Geels, C., Winther, M., Andersson, C., Jalkanen, J.-P., Brandt, J., Frohn, L. M., Im, U., Leung, W., & Christensen, J. H. (2021). Projections of shipping emissions and the related impact on air pollution and human health in the Nordic region. Atmospheric Chemistry and Physics, 21(16), 12495–12519. https://doi.org/10.5194/acp-21-12495-2021

Gilbert, P., Walsh, C., Traut, M., Kesieme, U., Pazouki, K., & Murphy, A. (2018). Assessment of full life-cycle air emissions of alternative shipping fuels. Journal of Cleaner Production, 172, 855–866. https://doi.org/10.1016/j.jclepro.2017.10.165

Gong, W., Beagley, S. R., Cousineau, S., Sassi, M., Munoz-Alpizar, R., Ménard, S., Racine, J., Zhang, J., Chen, J., Morrison, H., Sharma, S., Huang, L., Bellavance, P., Ly, J., Izdebski, P., Lyons, L., & Holt, R. (2018). Assessing the impact of shipping emissions on air pollution in the Canadian Arctic and northern regions: Current and future modelled scenarios. Atmospheric Chemistry and Physics, 18(22), 16653–16687. https://doi.org/10.5194/acp-18-16653-2018

International Maritime Organisation. (2009). Second IMO GHG Study 2009. https://wwwcdn.imo.org/localresources/en/OurWork/Environment/Documents/SecondIMOGHGStudy2009.pdf

International Maritime Organisation. (2021). Fourth IMO GHG Study 2020. https://wwwcdn.imo.org/localresources/en/OurWork/Environment/Documents/Fourth%20IMO%20GHG%20Study%202020%20-%20Full%20report%20and%20annexes.pdf

Jessop, P. G., Ikariya, T., & Noyori, R. (1995). Homogeneous hydrogenation of carbon dioxide. Chemical Reviews, 95(2), 259–272. https://doi.org/10.1021/cr00034a001

Martínez, D. Y., Jiménez-Gutiérrez, A., Linke, P., Gabriel, K. J., Noureldin, M. M. B., & El-Halwagi, M. M. (2014). Water and energy issues in gas-to-liquid processes: Assessment and integration of different gas-reforming alternatives. ACS Sustainable Chemistry & Engineering, 2(2), 216–225. https://doi.org/10.1021/sc4002643

Martínez, D. Y., Jiménez-Gutiérrez, A., Linke, P., Gabriel, K. J., Noureldin, M. M. B., & El-Halwagi, M. M. (2014). Water and energy issues in gas-to-liquid processes: Assessment and integration of different gas-reforming alternatives. ACS Sustainable Chemistry & Engineering, 2(2), 216–225. https://doi.org/10.1021/sc4002643

Schnurr, R. E. J., & Walker, T. R. (2019). Marine transportation and energy use. In Reference Module in Earth Systems and Environmental Sciences (p. B9780124095489094000). Elsevier. https://doi.org/10.1016/B978-0-12-409548-9.09270-8

Uhler, A. D., Stout, S. A., Douglas, G. S., Healey, E. M., & Emsbo-Mattingly, S. D. (2016). Chemical character of marine heavy fuel oils and lubricants. In Standard Handbook Oil Spill Environmental Forensics (pp. 641–683). Elsevier. https://doi.org/10.1016/B978-0-12-803832-1.00013-1

Viana, M., Hammingh, P., Colette, A., Querol, X., Degraeuwe, B., Vlieger, I. de, & van Aardenne, J. (2014). Impact of maritime transport emissions on coastal air quality in Europe. Atmospheric Environment, 90, 96–105. https://doi.org/10.1016/j.atmosenv.2014.03.046

I’m sure many of us have heard of oil spill disasters– when crude oil or refined petroleum products are accidentally released into the environment (E.g. British petroleum’s Deepwater Horizon Oil Spill in 2010, or the Amoco Cadiz oil spill in 1978), and are aware of the significant long-lasting negative impacts that they have on human health and the surrounding environment (D’Andrea & Reddy, 2018; Eklund et al., 2019; Helle et al., 2020; Rafferty, n.d.). 

However, in today’s post, I seek to uncover a pollutive practice that potentially results in 1 million tons of oil being released into our oceans annually, six times more than that of oil spill disasters, but often goes overlooked in the shipping industry (Maritime Intelligence, 2022). This practice is known as illegal blige dumping. 

What is blige dumping?

To understand blige dumping, we must first understand the formation of ‘bilge water’. Shipping vessels contain many complex systems, that include pumps, fittings, and extensive pipe networks. Oily wastewater, formed as a result of pipe leakages, spills, and in the routine maintenance of the ship, subsequently accumulates in the bilge (lowest part of a vessel’s hull), where it has come to be known as “Blige water” (Interpol, 2007; skytruth, n.d.). According to the International Convention for the Prevention of Pollution from Ships (MARPOL) set in place since the 1970s, vessels are required to treat bilge water, filtering the oil away before it can be legally discharged into the sea (Mohit, 2019). 

Why should we care?

However, despite this international law is in place to protect ocean ecosystems, non-profit environmental watchdog SkyTruth, have recently exposed the fact that many shipping vessels continue to illegally dump bilge water directly into oceans, in a bid to reduce cost from utilising pollution prevention equipment (Evanisko, 2020a). In a year-long analysis of radar satellite imagery in 2019– where SkyTruth have systematically searched for cases of illegal blige dumping by observing for dark and opaque slicks– they have found 163 slicks, each averaging 56 km in length. The presence of such slicks indicate likely cases of illegal blige dumping. However, these identified illegal bilge dumping incidents likely only represent a small percentage of total dumping incidents due to limited satellite coverage over the open oceans, where most occurences of bilge dumping are likely to take place (Evanisko, 2020a; Nicholls, 2018). Figure 1 depicts likely bilge dumping events, as recorded by SkyTruth in 2019, while Figure 2 categorises these events into regions. As seen from Figure 1 and 2, many of the observed incidents often coincide with popular shipping routes. 

Figure 1: Likely observed bilge dumping events identified by SkyTruth in 2019. (Evanisko, 2020a).

Figure 2: Likely bilge dump incidents identified by SkyTruth in 2019 by region. (Evanisko, 2020a).

This is especially so along the Straits of Malacca and its surrounding region of Southeast Asia, which accounted for approximately 70% of reported incidents in 2019. Figure 3 shows the presence of oily clumps on a beach in Bintan, believed to be as a result of illegal bilge dumping. 

Figure 3: Presence of oily clumps on a beach in Bintan, believed to be the result of daily illegal bilge dumping. (Hicks, 2020).

This is likely due to the Port of Singapore’s prohibition for vessels to discharge their bilge water, together with high costs charged for the removal of bilge water, which propels vessels to discharge their bilge water illegaly before docking into Singapore (Hicks, 2020; shipsandports, 2018). 

When compared to that of accidental oil spills, such as that of the Deepwater Horizon oil spill which released approximately 134 million gallons of oil, the amount of oil released during the dumping of bilge water can be argued to be insignificant (Rafferty, n.d.). However, studies have found such small releases of oil to cause negative impacts to marine ecosystems. For example, Brussaard et al’s (2016) study of short-lived oil spills have found small scale oil spills, similar in scale to that of bilge water dumping, to have “immediate adverse biological effects”, with high bioavailability and toxicity of oil being recorded fairly deep (8m) below the oil slicks, as well as a recorded decline in marine plankton, which can have subsequent knock-on negative effects on the functioning of marine ecosystems (p.1). 

Moving forward

Despite the negative environmental effects of bilge water dumping, many countries lack the political and regulatory pressure to ensure vessels comply with international standards. This is has been assumed to be due to the high costs involved, together with the lack of resources to deploy regular patrols (Hicks, 2020). 

However, not all hope is lost. In Europe, the European Maritime Safety Agency (EMSA)– through its CleanSeaNet initiative– have been closely monitoring and identifying possible incidents of illegal bilge dumping through satellite imagery. These information are then provided to the relevant EU countries, for further investigation, and subsequent prosecution of illegal offenders (EMSA, n.d.). Additionally, environmental watchdog SkyTruths have also been working towards automating the detection and identification of possible illegal bilge dumping activities, such that to quickly empower countries with the necessary information to eventually prosecute offenders (Evanisko, 2020b). With such improvements in technology to detect and identify illegal bilge dumping offenders, it is of activists hope, such as that of the members of SkyTruths, that it would compel shipping companies to now comply with international laws, and stop the practice of illegal bilge dumping. 

References

Brussaard, C. P. D., Peperzak, L., Beggah, S., Wick, L. Y., Wuerz, B., Weber, J., Samuel Arey, J., Van Der Burg, B., Jonas, A., Huisman, J., & Van Der Meer, J. R. (2016). Immediate ecotoxicological effects of short-lived oil spills on marine biota. Nature Communications, 7(1), 11206. https://doi.org/10.1038/ncomms11206

D’Andrea, M. A., & Reddy, G. K. (2018). The development of long-term adverse health effects in oil spill cleanup workers of the deepwater horizon offshore drilling rig disaster. Frontiers in Public Health, 6, 117. https://doi.org/10.3389/fpubh.2018.00117

Eklund, R. L., Knapp, L. C., Sandifer, P. A., & Colwell, R. C. (2019). Oil spills and human health: Contributions of the gulf of mexico research initiative. GeoHealth, 3(12), 391–406. https://doi.org/10.1029/2019GH000217

European Maritime Safety Agency. (n.d.). CleanSeaNet service. https://www.emsa.europa.eu/csn-menu.html

Evanisko, T. (2020, February 5). A systematic search for bilge dumping at sea: 2019 in review. SkyTruths. https://skytruth.org/2020/02/title-a-systematic-search-for-bilge-dumping-at-sea-2019-in-review/

Evanisoko, T. Blige dumping at sea: How can this be happening?. https://skytruth.org/2020/04/bilge-dumping-at-sea-how-can-this-be-happening/

Helle, I., Mäkinen, J., Nevalainen, M., Afenyo, M., & Vanhatalo, J. (2020). Impacts of oil spills on arctic marine ecosystems: A quantitative and probabilistic risk assessment perspective. Environmental Science & Technology, 54(4), 2112–2121. https://doi.org/10.1021/acs.est.9b07086

Hicks, R. (2020, March 11). Southeast Asia is the world’s bilge dumping hotspot—what can be done to stop ships discharging waste oil?. Eco-business. https://www.eco-business.com/news/southeast-asia-is-the-worlds-bilge-dumping-hotspot-what-can-be-done-to-stop-ships-discharging-waste-oil/?sw-signup=true

Interpol. (2007). Illegal oil discharges from vessels: Investigate manual. https://www.interpol.int/content/download/14079/file/EN_Oil%20Discharge%20Manual.pdf

Martime Intelligence. (2022, April 6). Illegal discharge, a common threat with disastrous ecological cost that can be mitigated by satellites and drones. https://maritime-intelligence.groupcls.com/illegal-discharge-a-common-threat/

Mohit. (2019, April 18). MARPOL annex 1 explained: How to prevent pollution from oil at sea. Marine Insight. https://www.marineinsight.com/maritime-law/marpol-annex-1-explained-how-to-prevent-pollution-from-oil-at-sea/

Nicholls, D. (2018, January 9). What we can see, in heat maps. SkyTruths. https://skytruth.org/2018/01/what-we-can-see-in-heat-maps/

Rafferty, J. (n.d.). 9 of the biggest oil spills in history. Britannica. https://www.britannica.com/list/9-of-the-biggest-oil-spills-in-history

Ships and Ports. (2018, November 30). Singapore prohibits ‘wash water’ discharge at ports from 2020. https://shipsandports.com.ng/singapore-prohibits-wash-water-discharge-at-ports-from-2020/

SkyTruths. Blige dumping. https://skytruth.org/bilge/

Contrary to the popular belief that our oceans are actually “Silent”, many marine organisms actually rely on their sense of hearing for essential life functions (Jones, 2019). Various marine mammals, fish and other organisms use sound as a primary method of communication, to locate mates and prey, as well as in the navigation and orientation of their environment (Simmonds & MacLennan, 2005). Even abiotic sound sources— sounds generated by the environment, such as by the crashing of waves or the sound of currents going over reefs, similarly remain important for marine organisms in orientating their environments (Peng et al., 2015; Popper et al., 2003). 

However increasing anthropogenic noise emissions, driven by the continued increase in the utilisation of our oceans and seas, have led to growing negative impacts on marine organisms (Peng et al., 2015). Figure 1 highlights a range of underwater anthropogenic sound sources. 

Figure 1: Undersea Sound Sources (Jones, 2019).

One significant source of anthropogenic underwater noise pollution is the shipping industry. In their review of the literature regarding the effects of ship noise on marine life, Erbe et al (2019) have described noise produced by ship traffic to be the “most ubiquitous and pervasive” source of anthropogenic noise in our oceans, responsible for the production of low-frequency noise that has been growing at an average rate of 3dB/decade (p.2). 

Ships mainly emit noise as a by-product when bubbles produced during the rotation of their propellers (a process known as cavitation) break underwater. Noise is also emitted from the vibration of the ship’s engine, and from the movement of the ship’s hull through the water (Clean Arctic Alliance, 2023; EMSA, n.d.). The level of noise pollution significantly increases with the size of the vessel. According to Hildebrand’s (2009) study of anthropogenic noise in the ocean, a small engine boat operating at 20 knots produces a much lower sound level of 60dB, when compared to a 173m cargo vessel operating at 16 knots, which produces 192dB, when measured at 1m away. Figure 2 below depicts the geographical distribution of global shipping noise emissions in 2019, created via a global modelling of noise source energy emissions measured from ships (63Hz). As seen in the Figure, the main shipping lanes (e.g. Straits of Malacca, Suez Canal, South China Sea and the English Channel), see the highest noise contributions from shipping. Figure 3 below highlights how noise energy emissions have generally been increasing along the world’s main shipping lanes. 

Figure 2: Global map of underwater noise emissions from ships in 2019, at 63Hz (Jalkanen et al., 2022).

Figure 3: Changes in underwater noise source energy emissions, 2014–2019, at 63Hz (Jalkanen et al., 2022).

Such noise pollution emitted by the shipping industry along shipping lanes has negatively impacted the marine biodiversity surrounding it, often altering their behaviours. One of the first pieces of evidence was presented by Rolland et al. (2012), who have shown how reduced ship traffic after the 11 September 2001 attacks, has led to a subsequent 6dB decrease in underwater noise, especially that below the range of 150Hz. This noise reduction was then associated with decreased stress levels in endangered right whales, as evidenced by lower levels of stress-related faecal hormone metabolites. This is evidence to show that increased exposure to low-frequency noise emissions from ships may be associated with chronic stress in whales. In other studies, dolphins were found to alter the frequency of their whistles in response to greater ship noise (Morisaka et al., 2005), while  humpback whales have been found to alter their foraging behaviour, with increasing ship noise associated with slower descent rates (Blair et al., 2016). Lastly, a study by Simpson et al (2016) has found the presence of underwater anthropogenic noise to increase fish mortality by predation. 

Having gained an understanding of the harmful impacts that noise pollution from the shipping industry has on marine life, in a subsequent blog, we will examine the various solutions proposed for this problem. 

References 

Blair, H. B., Merchant, N. D., Friedlaender, A. S., Wiley, D. N., & Parks, S. E. (2016). Evidence for ship noise impacts on humpback whale foraging behaviour. Biology Letters, 12(8), 20160005. https://doi.org/10.1098/rsbl.2016.0005

Clean Arctic Alliance. (2023, February 1). NGOs call on UN shipping body to reduce underwater noise impact on marine life. Eco-Business. https://www.eco-business.com/press-releases/ngos-call-on-un-shipping-body-to-reduce-underwater-noise-impact-on-marine-life/#:~:text=An%20important%20source%20of%20continuous,impact%20on%20the%20Arctic%20ecosystem

Erbe, C., Marley, S. A., Schoeman, R. P., Smith, J. N., Trigg, L. E., & Embling, C. B. (2019). The effects of ship noise on marine mammals—A review. Frontiers in Marine Science, 6, 606. https://doi.org/10.3389/fmars.2019.00606

European Maritime Safety Agency. (n.d.). Underwater noise. https://www.emsa.europa.eu/protecting-the-marine-environment/underwater-noise.html#:~:text=Ships%20are%20reported%20to%20be,the%20hull%20through%20the%20water

Hildebrand, J. (2009). Anthropogenic and natural sources of ambient noise in the ocean. Marine Ecology Progress Series, 395, 5–20. https://doi.org/10.3354/meps08353

Jalkanen, J.-P., Johansson, L., Andersson, M. H., Majamäki, E., & Sigray, P. (2022). Underwater noise emissions from ships during 2014–2020. Environmental Pollution, 311, 119766. https://doi.org/10.1016/j.envpol.2022.119766

Jones, N. (2019, April 10). Ocean uproar: Saving marine life from a barrage of noise. Nature. https://www.nature.com/articles/d41586-019-01098-6

Morisaka, T., Shinohara, M., Nakahara, F., & Akamatsu, T. (2005). Effects of ambient noise on the whistles of indo-pacific bottlenose dolphin populations. Journal of Mammalogy, 86(3), 541–546. https://doi.org/10.1644/1545-1542(2005)86[541:EOANOT]2.0.CO;2

Peng, C., Zhao, X., & Liu, G. (2015). Noise in the sea and its impacts on marine organisms. International Journal of Environmental Research and Public Health, 12(10), 12304–12323. https://doi.org/10.3390/ijerph121012304

Popper, A., Fay, R., Platt, C., & Sand, O. (2003). Sound detection mechanisms and capabilties of Teleost fishes. In S. P. Collin, & N. J. Marshall (Eds.), In sensory processing in aquatic environments (pp. 3-38). Springer. 

Rolland, R. M., Parks, S. E., Hunt, K. E., Castellote, M., Corkeron, P. J., Nowacek, D. P., Wasser, S. K., & Kraus, S. D. (2012). Evidence that ship noise increases stress in right whales. Proceedings of the Royal Society B: Biological Sciences, 279(1737), 2363–2368. https://doi.org/10.1098/rspb.2011.2429

Simmonds, E. J., MacLennan, D. N., & MacLennan, D. N. (2005). Fisheries acoustics: Theory and practice (2nd ed). Blackwell Science.

Simpson, S. D., Radford, A. N., Nedelec, S. L., Ferrari, M. C. O., Chivers, D. P., McCormick, M. I., & Meekan, M. G. (2016). Anthropogenic noise increases fish mortality by predation. Nature Communications, 7(1), 10544. https://doi.org/10.1038/ncomms10544

In the shipping industry, ballast is the extra weight that is added to large ships, in order to balance their weight and ensure stability during voyage (clearseas, 2021). Often, it is in the form of ballast water, where through the process of ballasting, water from the sea or visiting ports is pumped into the ballast tanks of the ships, thereby adding extra weight to the ship. This water is then discharged when the extra weight is no longer needed (often when cargo is loaded). This process is depicted in Figure 1. 

Figure 1: How ballast water is used to stabilize vessels. (Danfoss, 2022).

According to the International Maritime Organisation, as a result of the practice of ballasting, over 10 billion tonnes of ballast water is transferred around the world annually (International Maritime Organisation, 2019). However, the process of discharging ballast water can be highly pollutive. This is because in the pumping of ballast water, microscopic organisms– bacteria, microbes, pathogens, invertebrates, eggs, cysts, and larvae of various species, are concurrently transferred in (clearseas,2021). Thereafter, should untreated ballast water be discharged into other areas, it can disrupt and threaten local marine environments through the potential release of invasive aquatic nonindigenous species (NIS) (Casas-Monroy et al., 2014). These NIS can compete with native species for limited resources, potentially causing native species to go extinct (Ricciardi et al., 2013; Simberloff et al., 2013). Figure 2 depicts how invasive marine species have been transferred around the world through the discharge of ballast water. These have significant economic costs. Examples of costs incurred include the depletion of fish stock, the higher cost of maintaining NIS-damaged equipment, as well as increased costs from mitigation programs (Coulette et al., 2006). Couletti et al. (2006) have projected the invasion of NIS to cost Canada between Can$13.3 to Can$34.5 billion each year.

Figure 2: Transfer pathways of invasive marine species around the world through discharge of ballast water. (Danfoss, 2022).

Additionally, the release of ballast water possible pathogens and bacteria may also lead to the spread of waterborne diseases (Ruiz et al., 2000). For instance, in July 1992, Vibro cholerae (Bacteria that causes cholera), found in the waters of the USA was determined by the US Food and Drug Administration (FDA) to have been the result of the discharge of ballast water that had their last port in call in South America (McCarthy & Khambaty, 1994). 

In response to environmental concerns relating to the discharge of ballast water, the International Maritime Organisation introduced 2004, the “International Convention for the Control and Management of Ships’ Ballast Water and Sediments”. Under the Convention, all ships will be obligated to put into place a “Ballast Water Management Plan” that involves maintaining a ballast water record book and following established ballast water management procedures that meet specified standards (International Maritime Organization, n.d.).

However, while the convention has been put into force since 2017, its enforcement has been argued to be weak. In Ng et al’s (2018) examination of the ballast waters of six ships docked off the Singapore harbour, they found ballast waters of two of the six ships to not meet the stipulated requirements of the Ballast Water Management Convention, with Enterococci values (indicator of disease-causing bacteria and viruses) more than three times higher than the acceptable limits. In addition, non-toxigenic species of V.chloera, V.parahaemolyticus, and V.culnificus were also detected in at least one of the ships. It is therefore apparent that more can be done to reduce pollution caused by ballast water discharge. 

References 

Casas-Monroy, O., Linley, R.D., Adams, J.K., Chan, F.T., Drake, D.A.R., & Bailey, S.A. (2014). National risk assessment for introduction of aquatic nonindigenous species to Canada by ballast water. Canadian Science Advisory Secretariat. https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/352598.pdf

ClearSeas, 2021. Ballast water management: Stopping the spread of invasive species by ships. https://clearseas.org/en/blog/ballast-water-management-stopping-the-spread-of-invasive-species-by-ships/#:~:text=Large%20cargo%20ships%20use%20ballast,into%20a%20new%20marine%20environment.

Colautti, R. I., Bailey, S. A., van Overdijk, C. D. A., Amundsen, K., & MacIsaac, H. J. (2006). Characterised and projected costs of nonindigenous species in canada. Biological Invasions, 8(1), 45–59. https://doi.org/10.1007/s10530-005-0236-y

Danfoss. (2022). How to comply with ballast water regulation. https://assets.danfoss.com/documents/latest/197913/AC290731004318en-000102.pdf

International Maritime Organization. (2019). Ballast water management– the control of harmful invasive species. https://www.imo.org/en/MediaCentre/HotTopics/Pages/BWM-default.aspx

International Maritime Organization. (n.d.). International convention for the control and m management of ships’ ballast water and sediments (BWM). https://www.imo.org/en/About/Conventions/Pages/International-Convention-for-the-Control-and-Management-of-Ships%27-Ballast-Water-and-Sediments-(BWM).aspx

McCarthy, S. A., & Khambaty, F. M. (1994). International dissemination of epidemic Vibrio cholerae by cargo ship ballast and other nonpotable waters. Applied and Environmental Microbiology, 60(7), 2597–2601. https://doi.org/10.1128/aem.60.7.2597-2601.1994

Ricciardi, A., Hoopes, M. F., Marchetti, M. P., & Lockwood, J. L. (2013). Progress toward understanding the ecological impacts of nonnative species. Ecological Monographs, 83(3), 263–282. https://doi.org/10.1890/13-0183.1

Ruiz, G. M., Rawlings, T. K., Dobbs, F. C., Drake, L. A., Mullady, T., Huq, A., & Colwell, R. R. (2000). Global spread of microorganisms by ships. Nature, 408(6808), 49–50. https://doi.org/10.1038/35040695

Simberloff, D., Martin, J.-L., Genovesi, P., Maris, V., Wardle, D. A., Aronson, J., Courchamp, F., Galil, B., García-Berthou, E., Pascal, M., Pyšek, P., Sousa, R., Tabacchi, E., & Vilà, M. (2013). Impacts of biological invasions: What’s what and the way forward. Trends in Ecology & Evolution, 28(1), 58–66. https://doi.org/10.1016/j.tree.2012.07.013

Indeed, as seen in the last blog entry, when compared to shipping of goods by air, land, and rail, the shipping of goods by sea is a relatively cleaner form of transport. In this week’s blog entry, we will reveal how emissions from the shipping industry significantly contribute to air pollution. 

Emissions from shipping produce pollutants in the form of exhaust gases and particles. These include carbon dioxide (CO2), nitrogen oxides (NOx), sulfur dioxide (SO2), carbon monoxide (CO), volatile organic compounds (VOCs), particulate sulfate (SO4), black carbon (BC), particulate organic matter (OM) (Geels et al., 2021; Gong et al., 2018). 

Globally, these emissions are significant. For a start, the collective shipping industry contributes to around 940 million tonnes of CO2 annually (UKRI, 2021). This renders the industry to be a significant source of greenhouse gas emissions, accounting for around 2.5% of the world’s total CO2 emissions. In addition to CO2, shipping contributes to around 15% of global anthropogenic NOx and 5-8% of global SOx emissions (Eyring et al., 2005; Corbett et al., 2007).

Locally, many studies have also found shipping emissions to also contribute greatly to air pollution in coastal regions. In a review of research on shipping emissions in Europe by Viana et al. (2014), they found shipping to contribute to between 7-24% of NO2 levels (Figure 1), 1-7% of ambient air PM10 levels,, 1-14% of PM2.5, and at least 11% of PM1 (Figure 2). Similarly, Zhang et al. (2017) review of research on shipping emissions in China has found ship emissions at ports to significantly contribute to air pollution in coastal areas (Figures 3 & 4). 

Figure 1: Contribution from shipping emissions to air quality (NO2 and SO2 across Europe). (Source: Viana et al., 2014).

Figure 2: Contribution from shipping emissions to air quality (PM10, PM2.5 and PM1) across Europe. (Source: Viana et al., 2014).

Figure 3: Ship emission in ports in China reported in literature. (Source: Zhang et al., 2017).

Figure 4: Map representation of ship emissions of ports in China–Based on figures from the above table. (Source: Zhang et al., 2017).

These air pollutants can negatively affect the environment in three main ways : 

1. The formation of ozone (O3),  SO4 particles from ship emissions, together with the direct emission of CO2 and BC, are climate-forcing agents, which subsequently impact the radiative balance of the earth, therefore contributing to global warming (Gong et al., 2018). 
2. The release of SO2 and NOx also reacts with water vapour in the air, transforming into sulfuric acid (H2SO4) and nitric acid (HNO3). The subsequent formation of acid rain has negative impacts on the environment, such as on forests and marine ecosystems. (Streets et al., 1997). 
3. Formation of ozone (O3) and fine particulate matter (e.g. PM2.5)— through the oxidation of SO2 and the formation and production of SO4 particles, degrading air quality and rendering subsequent negative impacts on human health (Yau et al., 2013). For instance, Lin et al’s (2018) have found emissions from shipping pollution to be positively associated with increased cardiovascular mortality in Guangzhou, China. 

However, while it seems obvious that a reduction in shipping emissions would bring benefits to both the environment, and to human health, a solution that seeks to downsize the shipping industry is not feasible. This is because of the continued reliance on the shipping industry for the transportation of goods and resources around the world. 

Furthermore, the growth of the shipping industry is unlikely to slow down anytime soon. One contributing factor is the increasing retreat of Arctic sea ice, which has increased the prospect of the formation of new transit routes (e.g. Northern Sea Route, Northwest Passage, and Transpolar Sea Route). These would likely result in an increase in shipping activities in the Arctic region in the future (Gong et al., 2018). This is evident in Jing et al’s (2021) projection of CO2 emission from shipping activity in the Arctic, where they have projected CO2 emissions to increase by 1.76 times by 2050, under business as usual (BAU) scenarios. This increase in CO2 emissions would not only aggravate the warming and melting of Arctic sea ice, but the emission of accompanying air pollutants would also negatively harm the surrounding environment. 

References: 

Corbett, J. J., Winebrake, J. J., Green, E. H., Kasibhatla, P., Eyring, V., & Lauer, A. (2007). Mortality from ship emissions: A global assessment. Environmental Science & Technology, 41(24), 8512–8518. https://doi.org/10.1021/es071686z

Eyring, V., Isaksen, I. S. A., Berntsen, T., Collins, W. J., Corbett, J. J., Endresen, O., Grainger, R. G., Moldanova, J., Schlager, H., & Stevenson, D. S. (2010). Transport impacts on atmosphere and climate: Shipping. Atmospheric Environment, 44(37), 4735–4771. https://doi.org/10.1016/j.atmosenv.2009.04.059

Geels, C., Winther, M., Andersson, C., Jalkanen, J.-P., Brandt, J., Frohn, L. M., Im, U., Leung, W., & Christensen, J. H. (2021). Projections of shipping emissions and the related impact on air pollution and human health in the Nordic region. Atmospheric Chemistry and Physics, 21(16), 12495–12519. https://doi.org/10.5194/acp-21-12495-2021

Gong, W., Beagley, S. R., Cousineau, S., Sassi, M., Munoz-Alpizar, R., Ménard, S., Racine, J., Zhang, J., Chen, J., Morrison, H., Sharma, S., Huang, L., Bellavance, P., Ly, J., Izdebski, P., Lyons, L., & Holt, R. (2018). Assessing the impact of shipping emissions on air pollution in the Canadian Arctic and northern regions: Current and future modelled scenarios. Atmospheric Chemistry and Physics, 18(22), 16653–16687. https://doi.org/10.5194/acp-18-16653-2018

Jing, D., Dai, L., Hu, H., Ding, W., Wang, Y., & Zhou, X. (2021). CO2 emission projection for Arctic shipping: A system dynamics approach. Ocean & Coastal Management, 205, 105531. https://doi.org/10.1016/j.ocecoaman.2021.105531

Lin, H., Tao, J., Qian, Z. (Min), Ruan, Z., Xu, Y., Hang, J., Xu, X., Liu, T., Guo, Y., Zeng, W., Xiao, J., Guo, L., Li, X., & Ma, W. (2018). Shipping pollution emission associated with increased cardiovascular mortality: A time series study in Guangzhou, China. Environmental Pollution, 241, 862–868. https://doi.org/10.1016/j.envpol.2018.06.027

Streets, D. G., Carmichael, G. R., & Arndt, R. L. (1997). Sulfur dioxide emissions and sulfur deposition from international shipping in Asian waters. Atmospheric Environment, 31(10), 1573–1582. https://doi.org/10.1016/S1352-2310(96)00204-X

UK Research and Innovation. (2021, August 10). Shipping industry reduces carbon emissions with space technology. UKRI. https://www.ukri.org/news/shipping-industry-reduces-carbon-emissions-with-space-technology/

Viana, M., Hammingh, P., Colette, A., Querol, X., Degraeuwe, B., Vlieger, I. de, & van Aardenne, J. (2014). Impact of maritime transport emissions on coastal air quality in Europe. Atmospheric Environment, 90, 96–105. https://doi.org/10.1016/j.atmosenv.2014.03.046

Yau, P. S., Lee, S. C., Cheng, Y., Huang, Y., Lai, S. C., & Xu, X. H. (2013). Contribution of ship emissions to the fine particulate in the community near an international port in Hong Kong. Atmospheric Research, 124, 61–72. https://doi.org/10.1016/j.atmosres.2012.12.009

Zhang, Y., Yang, X., Brown, R., Yang, L., Morawska, L., Ristovski, Z., Fu, Q., & Huang, C. (2017). Shipping emissions and their impacts on air quality in China. Science of The Total Environment, 581–582, 186–198. https://doi.org/10.1016/j.scitotenv.2016.12.098