Following the Fukushima Daiichi Nuclear Power Plant (FDNPP) disaster in 2011, the continued release of damaged nuclear fuel into the cooling water has resulted in the accumulation of long-lived radionuclides in the contaminated water (Song, 2018). This cooling water is a mixture of groundwater, seawater, and is recirculated in tanks to remove decay heat before being filtered and stored away in tanks (Tsoi, 2023), thereby increasing the concentration of radionuclides over time. As of 2021, more than 1.25 million tonnes of seawater has been pumped through the damaged units (Nogrady, 2021).

However, with groundwater leaking into these tanks has resulted in increasing volumes of wastewater to be stored on site, along with higher incidences of contaminated wastewater leaking into the environment (Uchida et al., 2017) (Figure 2).

In particular, radioactive caesium isotopes 134Cs and 137Cs—with half-lives of 30 years and 2.1 years respectively—make up the greatest proportion of radioactivity in this cooling water (Lehto et al., 2018). To mitigate the release of these radionuclides, the contaminated water is processed through caesium absorbing equipment to remove caesium and strontium (Agency for Natural Resources and Energy, 2020). Thereafter, the wastewater is further purified through the Advanced Liquid Processing System (ALPS) to remove the remaining radioisotopes, with the exception of tritium (Yamanishi et al., 2019). As tritium cannot be removed from the wastewater via ‘conventional’ chemical methods (Shozugawa et al., 2016, as cited in Querfeld et al., 2019), this has raised concerns about tritium leakages into the environment. 

As briefly mentioned in a previous blog post, the Japanese government has announced the decision to release more than a million tonnes of treated wastewater from the FDNPP starting this year. While the bulk of radionuclides have been treated and removed, the wastewater still contains radioactive tritium (Querfeld et al., 2019).  Simulation model results created by Zhao et al (2021) have shown that regardless of the discharge amount into open sea, the radioactive tritium plume is expected to be dispersed across the entire North Pacific Ocean in any case. Similar to the caesium, tritium can become bound to animal and plant tissue, accumulating in marine organisms and across food chains, resulting in human exposure to tritium (Normile, 2023).

As expected, the decision to release this wastewater has been met with significant opposition and backlash. Notably, Japan’s geographical neighbours such as China, Taiwan, and South Korea have openly protested against it, drawing voices of opposition from politicians, fishermen, and environmental activists (Shin, 2021).

References

Fukushima Daiichi Nuclear Power Station Contaminated water management What is “slurry”? Why is it generated? How is it stored? (2020, June 19). Agency for Natural Resources and Energy,METI. https://www.enecho.meti.go.jp/en/category/special/article/detail_157.html

Lehto, J., Koivula, R., Leinonen, H., Tusa, E., & Harjula, R. (2019). Removal of Radionuclides from Fukushima Daiichi Waste Effluents. Separation & Purification Reviews, 48(2), 122–142. https://doi.org/10.1080/15422119.2018.1549567

Nogrady, B. (2021). Scientists OK plan to release one million tonnes of waste water from Fukushima. Nature. https://doi.org/10.1038/d41586-021-01225-2

Normile, D. (2023). Fukushima wastewater release set to start soon. Science, 379(6630), 321–321. https://doi.org/10.1126/science.adg8346

Querfeld, R., Pasi, A.-E., Shozugawa, K., Vockenhuber, C., Synal, H.-A., Steier, P., & Steinhauser, G. (2019). Radionuclides in surface waters around the damaged Fukushima Daiichi NPP one month after the accident: Evidence of significant tritium release into the environment. Science of The Total Environment, 689, 451–456. https://doi.org/10.1016/j.scitotenv.2019.06.362

Reuters, & Shin, H. (2021, April 14). S.Korea aims to fight Japan’s Fukushima decision at world tribunal. Reuters. https://www.reuters.com/world/asia-pacific/skoreas-moon-seeks-international-litigation-over-japans-fukushima-water-decision-2021-04-14/

Song, J. H. (2018). An assessment on the environmental contamination caused by the Fukushima accident. Journal of Environmental Management, 206, 846–852. https://doi.org/10.1016/j.jenvman.2017.11.068

Transition from NORM to TENORM

Oil and gas deposits contain naturally-occurring radionuclides, such as the 238U series, 232Th series and 40K, which have been identified as Naturally Occurring Radioactive Materials, abbreviated as ‘NORM’ (Attallah et al., 2020). The operation of oil and gas equipment involves the precipitation of alkaline earth metals such as sulfates, carbonate and silicates, resulting in the production of TENORM (Abdelbary et al., 2019). The radionuclides produced by the aforementioned isotopes and their decay products then often end up either dissolved or suspended in produced water, resulting in various forms of waste such as sludge, mineral scales, and thin-films (El Afifi et al., 2023).

Radioactivity of TENORM wastes

Current literature posit that TENORM wastes contain radioactive concentrations of Ra-226 levels significantly higher than what is permitted by the International Atomic Energy Agency (IAEA) (Hilal et al., 2014). Due to its extremely long half-life and high abundance of its parent nuclide (238U), 226Ra remains as the superabundant radium isotope found on TENORM wastes (Attallah et al., 2019). Similar to the nature of phosphogypsum discussed in the previous blog article, these TENORM wastes resulting from oil and gas processing also give rise to the generation of radon gas, which produces alpha particles as it decays (Attallah et al., 2019). According to Alfifi et al (2023), the radiological hazard parameters of scale and sludge residues and produced water—specifically pertaining to 222Rn levels—have been found to exceed well beyond the allowed safe limits.

Public exposure to TENORM wastes can occur through direct exposure pathways or through inhalation and ingestion from contaminated soil and water sources arising from the disposal of TENORM wastes (ALNabhani et al., 2016). In light of this, the International Atomic Energy Agency (IAEA) has put forth safety standards for industrial activities which involve NORM, specifically with regard to radiation protection and radioactive waste management for the oil and gas industry (Ali et al., 2021). Unfortunately, these proposed safety standards are inadequate at reducing radiation exposure risks, with current TENORM waste disposal methods often exacerbating the distribution of radionuclides and their decay products. ALNabhani et al (2017) posit that waste products from oil and gas production—of which contain varying levels of TENORM—are often disposed of above ground or underground, exposing workers to radiation. An elaboration of these disposal methods are illustrated in the figure below:

Lack of management strategies

While the presence of TENORM in wastes generated by the oil and gas industry is not a new discovery, there is still insufficient research and understanding on the impacts of TENORM on public health and safety (ALNahbani et al., 2016). Furthermore, while the IAEA has proposed recommended measures, the implementation of these measures vary across governing bodies, and there is still an absence of a standardised set of regulations with regard to TENORM management and disposal (Ault et al., 2014).

In the US, sludge containing TENORM contents is first dewatered and stored in tanks for later disposal, while produced waters are injected into deep wells, and scale is sandblasted with water, and the removed scale is then stored in drums for later disposal (US Environmental Protection Agency, 2015). Elsewhere, the open dumping of produced water is legal in Brazil, and for several European countries as well (Landa, 2007).

References

Abdelbary, H. M., Elsofany, E. A., Mohamed, Y. T., Abo-Aly, M. M., & Attallah, M. F. (2019). Characterization and radiological impacts assessment of scale TENORM waste produced from oil and natural gas production in Egypt. Environmental Science and Pollution Research, 26(30), 30836–30846. https://doi.org/10.1007/s11356-019-06183-x

AL Nabhani, K., Khan, F., & Yang, M. (2016). Technologically Enhanced Naturally Occurring Radioactive Materials in oil and gas production: A silent killer. Process Safety and Environmental Protection, 99, 237–247. https://doi.org/10.1016/j.psep.2015.09.014

Ali, M. M. M., Li, Z., Zhao, H., Rawashdeh, A., Al Hassan, M., & Ado, M. (2021). Characterization of the health and environmental radiological effects of TENORM and radiation hazard indicators in petroleum waste –Yemen. Process Safety and Environmental Protection, 146, 451–463. https://doi.org/10.1016/j.psep.2020.11.016

Ali, M. M. M., Zhao, H., Li, Z., & Maglas, N. N. M. (n.d.). Concentrations of TENORMs in the petroleum industry and their environmental and health effects. RSC Advances, 9(67), 39201–39229. https://doi.org/10.1039/c9ra06086c

ALNabhani, K., Khan, F., & Yang, M. (2016). The importance of public participation in legislation of TENORM risk management in the oil and gas industry. Process Safety and Environmental Protection, 102, 606–614. https://doi.org/10.1016/j.psep.2016.04.030

ALNabhani, K., Khan, F., & Yang, M. (2017). Management of TENORMs produced during oil and gas operation. Journal of Loss Prevention in the Process Industries, 47, 161–168. https://doi.org/10.1016/j.jlp.2017.03.016

Attallah, M. F., Abdelbary, H. M., Elsofany, E. A., Mohamed, Y. T., & Abo-Aly, M. M. (2020). Radiation safety and environmental impact assessment of sludge TENORM waste produced from petroleum industry in Egypt. Process Safety and Environmental Protection, 142, 308–316. https://doi.org/10.1016/j.psep.2020.06.012

Attallah, M. F., Hamed, M. M., & El Afifi, E. M. (2019). Remediation of TENORM scale waste generated from petroleum industry using single and mixed micelles solutions. Journal of Molecular Liquids, 294, 111565. https://doi.org/10.1016/j.molliq.2019.111565

Ault, T., Krahn, S., & Croff, A. (2015). Radiological Impacts and Regulation of Rare Earth Elements in Non-Nuclear Energy Production. Energies, 8(3), Article 3. https://doi.org/10.3390/en8032066

El Afifi, E. M., Mansy, M. S., & Hilal, M. A. (2023). Radiochemical signature of radium-isotopes and some radiological hazard parameters in TENORM waste associated with petroleum production: A review study. Journal of Environmental Radioactivity, 256, 107042. https://doi.org/10.1016/j.jenvrad.2022.107042

Hilal, M. A., Attallah, M. F., Mohamed, G. Y., & Fayez-Hassan, M. (2014). Evaluation of radiation hazard potential of TENORM waste from oil and natural gas production. Journal of Environmental Radioactivity, 136, 121–126. https://doi.org/10.1016/j.jenvrad.2014.05.016

Landa, E. R. (2007). Naturally occurring radionuclides from industrial sources: Characteristics and fate in the environment. In G. Shaw (Ed.), Radioactivity in the Environment (Vol. 10, pp. 211–237). Elsevier. https://doi.org/10.1016/S1569-4860(06)10010-8

US EPA, O. (2015, April 22). TENORM: Oil and Gas Production Wastes [Overviews and Factsheets]. https://www.epa.gov/radiation/tenorm-oil-and-gas-production-wastes

Phosphate rock mining

Phosphate rock is predominantly mined and processed to obtain phosphorus – a key ingredient used to enhance plant productivity (Chen & Graedel, 2015). Currently, there are two predominant mining approaches for phosphate rock: open-pit mining, and underground hard-rock mining (Steiner et al., 2015). Following extraction, the phosphate rock is then processed to produce phosphoric acid, which is then converted to phosphate fertilisers (Liang et al., 2017). Here, phosphate rock undergoes wet chemical processing, which uses sulfuric acid to first digest phosphate minerals (Liang et al., 2018).

As shown Fig. 2, the wet process of phosphate rock generates two products: phosphoric acid and phosphogypsum (principally CaSO4.2H2O), with the latter being a waste product. Phosphogypsum, while mostly made up of calcium sulfate dihydrate, contains several impurities such as phosphoric acid, phosphates, fluorides and organic matter, and is usually in the form of a grey, damp, powder or silt (Saadaoui et al., 2017). Additionally, phosphogypsum also contains the bulk of naturally-occuring uranium, thorium, radium, and heavy metals (US Environmental Protection Agency, 2019). While the characteristics of phosphogypsum is heavily dependent on the phosphate ore composition and quality, wet processing has been found to result in the selective separation and concentration of naturally-occurring radium in phosphogypsum (Sahu et al., 2014). To elaborate, about 80% or radium is concentrated in phosphogypsum, while almost 86% and 70% of uranium and thorium respectively are concentrated in phosphoric acid instead (Tayibi et al., 2009). This has therefore raised concerns about the leaching of radioactive elements in disposal sites, as well as the release of radon gas into the atmosphere.

Global phosphogypsum production is estimated to be around 280 million tonnes per year, with 28% of it disposed into water bodies, and 58% of it stored in tailing ponds (Turner et al., 2022). The disposal of phosphogypsum in water bodies or storage in ponds or leaps are often done without purification (Rashad, 2017), thereby resulting in extensive contamination. Currently, phosphogypsum is managed using wet stacking, in which filtered phosphogypsum is mixed with water and pumped into settling ponds, and the solid residue is then placed into stacks (Turner et al., 2022). These phosphogypsum stacks pose multiple environmental risks, as they are often not watertight nor covered with any inert material (Tayibi et al., 2009). The percolation of water often induces edge outflows that consist of toxic wastewater and leachates, introducing heavy metals and radionuclides into the waters and sediments of estuarine systems (Guerrero et al., 2019). This is exemplified in the outflow of leachates in the phosphogypsum stacks of Huevela, a region in southwestern Spain, which has since led to the deep pollution of underlying salt-marsh sediments (Guerrero et al., 2019). 

The open storage of these phosphogypsum stacks has also been found to contain significant levels of radioactivity due to high radon concentrations in the waste stacks. This has been posited to lead to an increase in radon inhalation rates and consequently, atmospheric radon concentrations (López-Coto et al., 2014). As discussed in a previous blog, radon exposure and inhalation has been found to lead to lung cancer, with radon itself being responsible for half of the total effective dose received by the population.

References

Ben Abdelouahed, H., & Reguigui, N. (2011). Radiotracer investigation of phosphoric acid and phosphatic fertilizers production process. Journal of Radioanalytical and Nuclear Chemistry – J RADIOANAL NUCL CHEM, 289, 103–111. https://doi.org/10.1007/s10967-011-1035-9

Chen, M., & Graedel, T. E. (2015a). The potential for mining trace elements from phosphate rock. Journal of Cleaner Production, 91, 337–346. https://doi.org/10.1016/j.jclepro.2014.12.042

Chen, M., & Graedel, T. E. (2015b). The potential for mining trace elements from phosphate rock. Journal of Cleaner Production, 91, 337–346. https://doi.org/10.1016/j.jclepro.2014.12.042

Guerrero, J. L., Gutiérrez-Álvarez, I., Mosqueda, F., Olías, M., García-Tenorio, R., & Bolívar, J. P. (2019). Pollution evaluation on the salt-marshes under the phosphogypsum stacks of Huelva due to deep leachates. Chemosphere, 230, 219–229. https://doi.org/10.1016/j.chemosphere.2019.04.212

Liang, H., Zhang, P., Jin, Z., & DePaoli, D. (2017). Rare-earth leaching from Florida phosphate rock in wet-process phosphoric acid production. Minerals & Metallurgical Processing, 34(3), 146–153. https://doi.org/10.19150/mmp.7615

Liang, H., Zhang, P., Jin, Z., & DePaoli, D. W. (2018). Rare Earth and Phosphorus Leaching from a Flotation Tailings of Florida Phosphate Rock. Minerals, 8(9), Article 9. https://doi.org/10.3390/min8090416

López-Coto, I., Mas, J. L., Vargas, A., & Bolívar, J. P. (2014). Studying radon exhalation rates variability from phosphogypsum piles in the SW of Spain. Journal of Hazardous Materials, 280, 464–471. https://doi.org/10.1016/j.jhazmat.2014.07.025

(PDF) Radiotracer investigation of phosphoric acid and phosphatic fertilizers production process. (n.d.). Retrieved March 24, 2023, from https://www.researchgate.net/publication/251415281_Radiotracer_investigation_of_phosphoric_acid_and_phosphatic_fertilizers_production_process

Rashad, A. M. (2017). Phosphogypsum as a construction material. Journal of Cleaner Production, 166, 732–743. https://doi.org/10.1016/j.jclepro.2017.08.049

Saadaoui, E., Ghazel, N., Ben Romdhane, C., & Massoudi, N. (2017). Phosphogypsum: Potential uses and problems – a review. International Journal of Environmental Studies, 74(4), 558–567. https://doi.org/10.1080/00207233.2017.1330582

Sahu, S. K., Ajmal, P. Y., Bhangare, R. C., Tiwari, M., & Pandit, G. G. (2014). Natural radioactivity assessment of a phosphate fertilizer plant area. Journal of Radiation Research and Applied Sciences, 7(1), 123–128. https://doi.org/10.1016/j.jrras.2014.01.001

Silva, L. F. O., Oliveira, M. L. S., Crissien, T. J., Santosh, M., Bolivar, J., Shao, L., Dotto, G. L., Gasparotto, J., & Schindler, M. (2022). A review on the environmental impact of phosphogypsum and potential health impacts through the release of nanoparticles. Chemosphere, 286, 131513. https://doi.org/10.1016/j.chemosphere.2021.131513

Steiner, G., Geissler, B., Watson, I., & Mew, M. C. (2015). Efficiency developments in phosphate rock mining over the last three decades. Resources, Conservation and Recycling, 105, 235–245. https://doi.org/10.1016/j.resconrec.2015.10.004

Tayibi, H., Choura, M., López, F. A., Alguacil, F. J., & López-Delgado, A. (2009). Environmental impact and management of phosphogypsum. Journal of Environmental Management, 90(8), 2377–2386. https://doi.org/10.1016/j.jenvman.2009.03.007

Turner, L. E., Dhar, A., Naeth, M. A., Chanasyk, D. S., & Nichol, C. K. (2022). Effect of soil capping depth on phosphogypsum stack revegetation. Environmental Science and Pollution Research, 29(33), 50166–50176. https://doi.org/10.1007/s11356-022-19420-7

US EPA, O. (2019, February 11). What kinds of consumer products contain radioactive materials? [Overviews and Factsheets]. https://www.epa.gov/radiation/what-kinds-consumer-products-contain-radioactive-materials

Introduction to rare earth elements

Rare earth elements (REEs) refer to the group of 15 lanthanides, and are usually categorised into either of the two groups: light rare earth minerals (LREEs) and heavy rare earth minerals (HREEs), based on their atomic weight as shown in the table below:

Lanthanides (elements with atomic numbers from 58 to 71)
LREEs	HREEs
Lanthanum (La) Cerium (Ce) Praseodymium (Pr) Neodymium (Nd) Promethium (Pm) Samarium (Sm)	Europium (Eu) Gadolinium (Gd) Terbium (Tb) Dysprosium (Dy) Holmium (Ho) Erbium (Er) Thulium (Tm) Ytterbium (Yb) Lutetium (Lu)
Non-lanthanide elements: Yttrium (Y) Scandium (Sc)

Table 1: List of the 15 REEs (Source: Riesgo García et al., 2017)

These REEs often make up key components in defence technologies, such as lasers and satellites (Royer-Lavallée et al., 2020) and in the renewable energy sector, such as wind turbines and hybrid cars (EuRare, 2017, as cited in Costis et al., 2021). To elaborate further, Balaram (2019) further breaks down the main uses of REEs into the following categories:

REE deposits and the extraction of REEs

REEs are naturally occurring in geological deposits, and develop in virtually all major rock types, and multiple significant REE deposits can be found worldwide:

Despite the natural abundance of REEs, in which the concentrations of REEs far exceed the concentrations of many other primary produced metals that are mined on an industrial scale, REEs are rarely found in mineable ore deposits (Balachandran, 2014). Furthermore, REEs often occur collectively and are found in various minerals in the Earth’s crust, such as silicate, carbonate or phosphate minerals (Hoshino et al., 2016; Royer-Lavallée et al., 2020). In essence, the nature of REEs co-occurring with mineral ores of base metals to form rare earth ores, along with the high reactivity of REEs with most non-metals (Gwenzi et al., 2018) pose additional challenges to the extraction of REEs.

There are two main methods for REE mining: the first involves the removal of topsoil and creating a leaching pond, in which chemicals are added to the extract earth to separate metals. The second method involves drilling holes into the ground and pumping chemicals such as ammonium sulfate and ammonium chloride into the earth, which in turn also creates a leaching pond (Nayar, 2021; Standaert, 2019). Given that both approaches involve creating a leaching pond containing harsh, toxic chemicals, these extraction methods pose huge risks of groundwater contamination, which can then in turn affect entire waterways (Nayar, 2021). 

Following extraction, the REEs ores often undergo leaching processes to further refine and isolate the rare earth metals. This involves dissolving the ores in a suitable leaching agent before extracting the rare earth metals using methods such as precipitation, fractional crystallisation, and chromatography (Shahbaz, 2022).

Problems associated with REE mining activities

1. Acid Mine Drainage

Acid mine drainage (AMD) refers to the formation and movement of highly acidic water rich in heavy metals. AMD contains sulfuric acid – the result of chemical reactions between surface water and shallow subsurface water with rocks that contain sulfur-bearing minerals (United States Environmental Protection Agency, 2022). The extraction of REEs often results in the generation of AMD, and the toxicity of AMD can lead to the degradation of soils, water reservoirs, and rivers, which can in turn jeopardise the ecosystems present in these biospheres (Gomes et al., 2022). 

2. Waste Products from REE-related leaching processes

The use of concentrated hydrochloric acid, sulfuric acid, and nitric acid to leach REE from REE-bearing ores via hydrometallurgical processes can also pose significant environmental threats (Edahbi et al., 2019). The process of leaching REE-bearing ores generates two main waste products: waste rocks that are extracted to reach the orebody, and tailings which consist of finely ground ore and other chemicals used during the hydrometallurgical processes (Filho, 2016). Similar to AMD, the interaction of these aforementioned waste products with water and oxygen can give rise to the oxidation of sulfide minerals (Nordstrom, 2012).

Mine tailings are often dumped in tailing ponds, and the REE concentrations in these residues are often extremely high. These high concentrations, coupled with the fine particle sizes of these tailings, can result in radioactive pollution due to the introduction and diffusion of radioactive thorium-containing dust (Binnemans et al., 2015) over large areas. This radioactive dust is airborne, and can also migrate through soils and water bodies (Krasavtseva et al., 2021). Apart from becoming a source of ionising radiation, the radioactive dust also results in particulate matter formation, posing significant health risks (Marx et al., 2018)

Case study: Bayan Obo Rare Earth Mine

The Bayan Obo Ore Deposit, located in Inner Mongolia, China, is the world’s largest REE deposit, with China making up 42% of the global REE reserve base, in which 80% of China’s LREE resources are found in the Bayan Obo region (Fan et al., 2016). This ore deposit is also known as one of the most heavily polluted places in the world, due to the mismanagement of mining waste products, resulting in extensive contamination of farmland, water supplies, and air (Gramling, 2023). 

Due to the lack of environmental awareness and inadequate technologies to manage REE mining waste, mine tailings and other waste materials generated from China’s mining activities have resulted in a series of environmental impacts. These include the creation of derelict lands, known as ‘mining brownfields’ in China, as well as extensive soil pollution and huge economic loss (Pan & Li, 2016). For the Bayan Obo Deposit, 90% of the tailings are stored in the tailing dam of the Baotou Iron and Steel Group Company—established in 1965 with poor support capacity—and has since resulted in the development of huge brownfields (Pan & Li, 2016). This has been attributed to a large amount of these tailings being discharged directly into Inner Mongolia’s grassland ecosystem (Guo et al., 2013).

Apart from the poor structural integrity of these tailing ponds, the open stockpiling of rare earth tailings in Bayan Obo has also resulted in the deterioration of grassland resources, air pollution, and water and soil pollution via erosion and leaching processes (Guo et al., 2013). Another point of concern for communities living in the Bayan Obo region is that the main source of drinking water is groundwater located in the vicinity of the Bayan Obo mining area, therefore rendering drinking water as one of the REE exposure pathways (Liang et al., 2018). The open tailing dumps and surface mining activities have also resulted in higher concentrations of total suspended particulate (TSP) and PM10 in the Bayan Obo region, and these airborne pollutants have been found to be associated with respiratory and cardiovascular diseases, skin cancer, and gastrointestinal issues (Wang et al., 2014).

References

Balachandran, G. (2014). Case Study 1—Extraction of Rare Earths for Advanced Applications. In S. Seetharaman (Ed.), Treatise on Process Metallurgy (pp. 1291–1340). Elsevier. https://doi.org/10.1016/B978-0-08-096988-6.09983-1

Balaram, V. (2019). Rare earth elements: A review of applications, occurrence, exploration, analysis, recycling, and environmental impact. Geoscience Frontiers, 10(4), 1285–1303. https://doi.org/10.1016/j.gsf.2018.12.005

Binnemans, K., Jones, P. T., Blanpain, B., Van Gerven, T., & Pontikes, Y. (2015). Towards zero-waste valorisation of rare-earth-containing industrial process residues: A critical review. Journal of Cleaner Production, 99, 17–38. https://doi.org/10.1016/j.jclepro.2015.02.089

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Costis, S., Mueller, K. K., Coudert, L., Neculita, C. M., Reynier, N., & Blais, J.-F. (2021). Recovery potential of rare earth elements from mining and industrial residues: A review and cases studies. Journal of Geochemical Exploration, 221, 106699. https://doi.org/10.1016/j.gexplo.2020.106699

Edahbi, M., Plante, B., & Benzaazoua, M. (2019). Environmental challenges and identification of the knowledge gaps associated with REE mine wastes management. Journal of Cleaner Production, 212, 1232–1241. https://doi.org/10.1016/j.jclepro.2018.11.228

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Marx, J., Schreiber, A., Zapp, P., & Walachowicz, F. (2018). Comparative Life Cycle Assessment of NdFeB Permanent Magnet Production from Different Rare Earth Deposits. ACS Sustainable Chemistry & Engineering. https://doi.org/10.1021/acssuschemeng.7b04165

Not So “Green” Technology: The Complicated Legacy of Rare Earth Mining. (2021, August 12). Harvard International Review. https://hir.harvard.edu/not-so-green-technology-the-complicated-legacy-of-rare-earth-mining/

Pan, Y., & Li, H. (2016). Investigating Heavy Metal Pollution in Mining Brownfield and Its Policy Implications: A Case Study of the Bayan Obo Rare Earth Mine, Inner Mongolia, China. Environmental Management, 57(4), 879–893. https://doi.org/10.1007/s00267-016-0658-6

Peiravi, M., Dehghani, F., Ackah, L., Baharlouei, A., Godbold, J., Liu, J., Mohanty, M., & Ghosh, T. (2021). A Review of Rare-Earth Elements Extraction with Emphasis on Non-conventional Sources: Coal and Coal Byproducts, Iron Ore Tailings, Apatite, and Phosphate Byproducts. Mining, Metallurgy & Exploration, 38(1), 1–26. https://doi.org/10.1007/s42461-020-00307-5

Puko, T. (2020, April 26). Pentagon Invests in Strategic Metals Mine, Seeking to Blunt Chinese Dominance. Wall Street Journal. https://www.wsj.com/articles/pentagon-invests-in-strategic-metals-mine-seeking-to-blunt-chinese-dominance-11587924001

Rare earth mining may be key to our renewable energy future. But at what cost? (2023, January 11). https://www.sciencenews.org/article/rare-earth-mining-renewable-energy-future

Riesgo García, M. V., Krzemień, A., Manzanedo del Campo, M. Á., Menéndez Álvarez, M., & Gent, M. R. (2017). Rare earth elements mining investment: It is not all about China. Resources Policy, 53, 66–76. https://doi.org/10.1016/j.resourpol.2017.05.004

Royer-Lavallée, A., Neculita, C. M., & Coudert, L. (2020). Removal and potential recovery of rare earth elements from mine water. Journal of Industrial and Engineering Chemistry, 89, 47–57. https://doi.org/10.1016/j.jiec.2020.06.010

Shahbaz, A. (2022). A systematic review on leaching of rare earth metals from primary and secondary sources. Minerals Engineering, 184, 107632. https://doi.org/10.1016/j.mineng.2022.107632

Smith, M. P., Moore, K., Kavecsánszki, D., Finch, A. A., Kynicky, J., & Wall, F. (2016). From mantle to critical zone: A review of large and giant sized deposits of the rare earth elements. Geoscience Frontiers, 7(3), 315–334. https://doi.org/10.1016/j.gsf.2015.12.006

US EPA, O. (2015, September 15). Abandoned Mine Drainage [Overviews and Factsheets]. https://www.epa.gov/nps/abandoned-mine-drainage

Wang, L., Liang, T., Zhang, Q., & Li, K. (2014). Rare earth element components in atmospheric particulates in the Bayan Obo mine region. Environmental Research, 131, 64–70. https://doi.org/10.1016/j.envres.2014.02.006

Yuan, J., Ding, Z., Bi, Y., Li, J., Wen, S., & Bai, S. (2022). Resource Utilization of Acid Mine Drainage (AMD): A Review. Water, 14(15), Article 15. https://doi.org/10.3390/w14152385

Anthropogenic sources of radioactive pollution in oceans are many and can include the following:

Having discussed the issue of dumping nuclear waste in a previous blog post, this blog post will focus on radioactive pollution originating from nuclear accidents—such as the Fukushima Dai-ichi Nuclear Power Plant disaster—and how radioactive particles can be dispersed by ocean currents. This blog post will then conclude with a discussion on the impacts of these radioactive substances in oceans.

Apart from the atmospheric deposition of radioactive particles via nuclear fallout, the drainage of water from nuclear power plant (NPP) reactors following NPP-related disasters has also resulted in the contamination of neighbouring water bodies. Additionally, the rain-induced wash off has from the soil has also resulted in the introduction of radioactive substances into the sea (Prants et al., 2011). To better understand these processes, we will be examining the aftermath of the Fukushima Daiichi Nuclear Power Plant (FDNPP) and how the released radionuclides were dispersed.

The events of the Fukushima nuclear accident

The Fukushima nuclear accident occurred on 11 March 2011 following a 9.0-magnitude earthquake, coupled with a resultant tsunami event (Kim et al., 2013). Following this, the Fukushima Daiichi Nuclear Power Station lost external power supplies and AC power, which then resulted in reactors and spent fuel pods losing their cooling capabilities as well. This then led to explosions in three out of the six nuclear power units, along with serious damage towards the reactor core of another power unit (Hasegawa, 2012). The Fukushima nuclear disaster was rated 7 on the International Nuclear Event Scale, and has since been deemed as the first example of a “Quake and Nuke Disaster Complex”, as well as the first major accident of a NPP located on the coast (Hasegawa, 2012). Prants et al (2011) posit that the propagation of radioactive pollution from the NPP stems from two sources: the direct discharge of nuclear wastewater from the NPP, and deposition of radioactive substances as atmospheric precipitation into the ocean.

One of the most contentious issues regarding the aftermath of the Fukushima nuclear disaster is the release of around 10,400 cubic metres of contaminated wastewater into the Pacific Ocean in order to free up storage for wastewater with even higher contamination levels (World Nuclear Association, 2022). Additionally, despite receiving criticism for the initial release of contaminated wastewater, the Japanese government has announced plans in April 2021 to release huge quantities of contaminated nuclear wastewater into the Pacific Ocean from late 2022 to early 2023, over the next 30 years (Greenpeace, 2020, as cited in Yang et al., 2022). These actions were met with considerable opposition criticism from neighbouring countries (Norio et al., 2012), given the dispersal of radioactive substances via ocean currents as shown in the figure below:

Apart from contaminating oceans, the deposition of radionuclides on Japanese soils can also lead to a possibility of introducing contaminated sediments into rivers via runoff and erosion processes (Chartin et al., 2013). Alternatively, deposited radionuclides can also be deposited via soluble media—a process known as ‘liquid wash off’—into rivers and other water bodies (Pratama, 2015). Such occurrences can prove to be problematic, with coastal rivers becoming a constant supply of contaminated sediment to the Pacific Ocean (Chartin et al., 2013).

Apart from the volume of wastewater dumped, the contamination of the marine environment following the Fukushima nuclear disaster is also characterised by the location of the coastal waters of the FDNPP, which is located in the zone at where the Kuroshio and Oyashio currents interact (Bailly du Bois et al., 2011). These currents influence the extent of which the radioactive pollution is dispersed, with the Kuroshio current carrying the radioactive plume towards the centre of the Pacific Ocean (Jayne et al., 2009, as cited in Bailly du Bois et al., 2011). 

Impacts and concerns

One of the biggest concerns is the introduction of Caesium-137 and Caesium-134 into the marine environment, as these Cs isotopes are essentially soluble in seawater and can be transported over long distances by marine currents and dissipated throughout the ocean water masses (Sanchez-Cabeza et al., 2011, as cited in Bailly du Bois et al., 2011). Additionally, other radionuclides also tend to bind to suspended particles, resulting in sedimentary contamination as they deposit onto the seafloor (Evrard et al., 2011). As such, the nature of these radionuclides not only makes it more challenging to track and monitor the dispersal of radioactive substances in water bodies, but also that it is easier for these radioactive substances to affect marine life on a larger scale. The latter has been reflected in how 40% of fish species between April 2011 and April 2012 were found to have exceeded the Japanese radioactive regulatory limit of 100 Bq/kg-wet for radioactive Cs (Wada et al., 2013). In response to this, the Japanese government stopped the distribution of contaminated fishery products and contaminated feed for aquaculture (Morita et al., 2019).

A simulation conducted by Behrens et al., (2012, as cited in Koo et al., 2014) estimates that the dispersion and dilution of radioactive substances by ocean current activity would help to decrease peak radioactivity in the seawater off Fukushima gradually. However, while the ocean is able to dilute and disperse radioactive substances due to its large volume, the long half-life radionuclides, such as Caesium-137 and Caesium-134, are likely to still remain in the marine environment for prolonged periods (Yu et al., 2015). Both short- and long-lived radioactive elements can be absorbed by plankton and kelp, which can then accumulate in marine animals across the food chain (Grossman, 2011), ultimately affecting humans who consume them. 

References

Adhiraga Pratama, M., Yoneda, M., Shimada, Y., Matsui, Y., & Yamashiki, Y. (2015). Future projection of radiocesium flux to the ocean from the largest river impacted by Fukushima Daiichi Nuclear Power Plant. Scientific Reports, 5(1), 8408. https://doi.org/10.1038/srep08408

Bailly du Bois, P., Laguionie, P., Boust, D., Korsakissok, I., Didier, D., & Fiévet, B. (2012). Estimation of marine source-term following Fukushima Dai-ichi accident. Journal of Environmental Radioactivity, 114, 2–9. https://doi.org/10.1016/j.jenvrad.2011.11.015

Buesseler, K. O. (2012). Fishing for Answers off Fukushima. Science, 338(6106), 480–482. https://doi.org/10.1126/science.1228250

Chartin, C., Evrard, O., Onda, Y., Patin, J., Lefèvre, I., Ottlé, C., Ayrault, S., Lepage, H., & Bonté, P. (2013). Tracking the early dispersion of contaminated sediment along rivers draining the Fukushima radioactive pollution plume. Anthropocene, 1, 23–34. https://doi.org/10.1016/j.ancene.2013.07.001

Evrard, O., Laceby, J. P., Onda, Y., Wakiyama, Y., Jaegler, H., & Lefèvre, I. (2016). Quantifying the dilution of the radiocesium contamination in Fukushima coastal river sediment (2011–2015). Scientific Reports, 6(1), Article 1. https://doi.org/10.1038/srep34828

Fukushima Daiichi Accident—World Nuclear Association. (n.d.). Retrieved March 6, 2023, from https://world-nuclear.org/information-library/safety-and-security/safety-of-plants/fukushima-daiichi-accident.aspx

Grossman, E. (n.d.). Radioactivity in the Ocean: Diluted, But Far from Harmless. Yale E360. Retrieved March 6, 2023, from https://e360.yale.edu/features/radioactivity_in_the_ocean_diluted_but_far_from_harmless

Hasegawa, K. (2012). Facing Nuclear Risks: Lessons from the Fukushima Nuclear Disaster. International Journal of Japanese Sociology, 21(1), 84–91. https://doi.org/10.1111/j.1475-6781.2012.01164.x

Kim, Y., Kim, M., & Kim, W. (2013). Effect of the Fukushima nuclear disaster on global public acceptance of nuclear energy. Energy Policy, 61, 822–828. https://doi.org/10.1016/j.enpol.2013.06.107

Koo, Y.-H., Yang, Y.-S., & Song, K.-W. (2014). Radioactivity release from the Fukushima accident and its consequences: A review. Progress in Nuclear Energy, 74, 61–70. https://doi.org/10.1016/j.pnucene.2014.02.013

Lu, Y., Yuan, J., Du, D., Sun, B., & Yi, X. (2021). Monitoring long-term ecological impacts from release of Fukushima radiation water into ocean. Geography and Sustainability, 2(2), 95–98. https://doi.org/10.1016/j.geosus.2021.04.002

Morita, T., Ambe, D., Miki, S., Kaeriyama, H., & Shigenobu, Y. (2020). Impacts of the Fukushima Nuclear Accident on Fishery Products and Fishing Industry. In M. Fukumoto (Ed.), Low-Dose Radiation Effects on Animals and Ecosystems: Long-Term Study on the Fukushima Nuclear Accident (pp. 31–41). Springer. https://doi.org/10.1007/978-981-13-8218-5_3

Norio, O., Ye, T., Kajitani, Y., Shi, P., & Tatano, H. (2011). The 2011 eastern Japan great earthquake disaster: Overview and comments. International Journal of Disaster Risk Science, 2(1), 34–42. https://doi.org/10.1007/s13753-011-0004-9

Pickard, W. F. (2010). Finessing the fuel: Revisiting the challenge of radioactive waste disposal. Energy Policy, 38(2), 709–714. https://doi.org/10.1016/j.enpol.2009.11.022

Yablokov, A. V. (2005). Meta-Analysis of the Radioactive Pollution of the Ocean. In E. Levner, I. Linkov, & J.-M. Proth (Eds.), Strategic Management of Marine Ecosystems (pp. 11–27). Springer Netherlands. https://doi.org/10.1007/1-4020-3198-X_1

Yagi, N. (2019). The State of Fisheries and Marine Species in Fukushima: Six Years After the 2011 Disaster. In T. M. Nakanishi, M. O`Brien, & K. Tanoi (Eds.), Agricultural Implications of the Fukushima Nuclear Accident (III): After 7 Years (pp. 211–220). Springer. https://doi.org/10.1007/978-981-13-3218-0_18

Yang, B., Yin, K., Li, X., & Liu, Z. (2022). Graph model under grey and unknown preferences for resolving conflicts on discharging Fukushima nuclear wastewater into the ocean. Journal of Cleaner Production, 332, 130019. https://doi.org/10.1016/j.jclepro.2021.130019

Yu, W., He, J., Lin, W., Li, Y., Men, W., Wang, F., & Huang, J. (2015). Distribution and risk assessment of radionuclides released by Fukushima nuclear accident at the northwest Pacific. Journal of Environmental Radioactivity, 142, 54–61. https://doi.org/10.1016/j.jenvrad.2015.01.005

What is radon?

Radon is a colourless and odourless gas and has been cited to be responsible for half of the natural radiation to which humans will be exposed to (Lorenzo-González et al., 2019). Specifically, Radon-222 stands as the most prevalent naturally-occurring isotope, as well as the most health significant to humans (Schwela & Kotzias, 2005). In general, these gaseous radon isotopes occur as a result of the natural radioactive decay of uranium-containing minerals found in bedrock, surficial materials, and groundwater (Missimer et al., 2019).

The prevalence of radon has proved to be problematic as the gas escapes easily from rocks and soils into the air, and subsequently tends to accumulate within enclosed indoor spaces such as houses and buildings (World Health Organisation [WHO], 2023).

 

Harmful effects of radon exposure

To date, radon is one of the 19 environmental carcinogens recognized by the WHO, and the International Agency for Research on Cancer has also similarly classified radon and its progeny as carcinogenic to humans (Li et al., 2020).

1. Lung cancer

Radon atoms can spontaneously decay or change into other atoms – resulting in a process known as radon progeny. These atoms can then attach themselves to dust particles present in indoor air, which can stick to the inner lining of the lung upon inhalation (National Research Council (US), 1999). The radiation emitted from the deposited radioactive particles can result in severe DNA damage (Riudavets et al., 2022), prompting cells to repair rapidly whilst introducing genetic errors in what has been termed as “genomic instability” (Stanley et al., 2019), thereby leading to lung cancer.

Radon currently stands as the overall second leading cause of lung cancer (US Environmental Protection Agency, 2023), and has been found to synergistic effects with cigarette smoke, leading to the increase of lung cancer risks in smokers (Kim & Ha, 2018). However, another alarming discovery is the fact that residential radon exposure has been found to be the leading cause of lung cancer in individuals who have never smoked before (Lorenzo-González et al., 2019).

2. Childhood leukemia

Ngoc et al. (2023) posit that children who grew up in homes with significant radon concentrations faced a much greater risk of developing childhood leukemia. Currently, researchers hypothesise that a small amount of radon is delivered to the bone marrow upon radon inhalation, which can then interfere with the development of leukocytes, thereby increasing the risk of leukemia (Tong et al., 2012).

 

Residential radon exposure

The concentration of residential radon depends on numerous factors:

Factors	Examples
Housing factors	·      Housing type ·      Decoration materials ·      Building materials ·      Fuel used ·      Domestic water
Environmental conditions	·      Temperature ·      Humidity ·      Atmospheric pressure
Time factors	·      Seasonality ·      Daytime/Nighttime
Ventilation capacity	·      Ventilation of indoor/outdoor air

Table 1: Factors that affect the concentration of residential radon (Source: Li et al., 2020)

While outdoor radon concentrations do not pose health risks to humans, human-made buildings have been found to artificially concentrate radon gas, amplifying radon exposure experienced by occupants. To elaborate, outdoor radon concentrations usually average around 5 Bq/m³-15 Bq/m³, which is significantly lower than the average of 142 Bq/m³ found in North American residential homes build after 1992 (Reddy et al., 2022).

These observations are further supported by a Canadian-based study, which discovered that newer residential buildings contain higher mean radon levels compared to older ones, along with higher occupancy rates within these newer buildings:

It is crucial to note that high radon exposure concentrations are prevalent phenomenon across regions, with countries such as South Korea similarly higher residential radon concentrations in houses built between 2011 and 2014 than those built between 1989 and 2009 (Kim & Ha, 2018). Indoor radon levels have also been recorded to be significantly higher during colder seasons due to closed windows and doors, resulting in an increased accumulation of radon within enclosed areas (Baltrėnas et al., 2020). As such, this might suggest that regions which experience cold temperatures might have populations which are at a higher risk of increased radon exposure and its repercussions.

 

References

About Radon. (n.d.). Retrieved February 23, 2023, from https://www.who.int/teams/environment-climate-change-and-health/radiation-and-health/environmental-exposure/radon/about

Baltrėnas, P., Grubliauskas, R., & Danila, V. (2020). Seasonal Variation of Indoor Radon Concentration Levels in Different Premises of a University Building. Sustainability, 12(15), Article 15. https://doi.org/10.3390/su12156174

CDC. (2022, December 22). Radon in the Home. Centers for Disease Control and Prevention. https://www.cdc.gov/radon/radon-facts.html

Kim, J.-H., & Ha, M. (2018). The Disease Burden of Lung Cancer Attributable to Residential Radon Exposure in Korean Homes. Journal of Korean Medical Science, 33(29), e223. https://doi.org/10.3346/jkms.2018.33.e223

Li, C., Wang, C., Yu, J., Fan, Y., Liu, D., Zhou, W., & Shi, T. (2020). Residential Radon and Histological Types of Lung Cancer: A Meta-Analysis of Case‒Control Studies. International Journal of Environmental Research and Public Health, 17(4), 1457. https://doi.org/10.3390/ijerph17041457

Lorenzo-González, M., Ruano-Ravina, A., Torres-Durán, M., Kelsey, K. T., Provencio, M., Parente-Lamelas, I., Leiro-Fernández, V., Vidal-García, I., Castro-Añón, O., Martínez, C., Golpe-Gómez, A., Zapata-Cachafeiro, M., Piñeiro-Lamas, M., Pérez-Ríos, M., Abal-Arca, J., Montero-Martínez, C., Fernández-Villar, A., & Barros-Dios, J. M. (2019). Lung cancer and residential radon in never-smokers: A pooling study in the Northwest of Spain. Environmental Research, 172, 713–718. https://doi.org/10.1016/j.envres.2019.03.011

Lorenzo-González, M., Torres-Durán, M., Barbosa-Lorenzo, R., Provencio-Pull, M., Barros-Dios, J. M., & Ruano-Ravina, A. (n.d.). Radon exposure: A major cause of lung cancer. Retrieved February 22, 2023, from https://www-tandfonline-com.libproxy1.nus.edu.sg/doi/epdf/10.1080/17476348.2019.1645599?needAccess=true&role=button

Missimer, T. M., Teaf, C., Maliva, R. G., Danley-Thomson, A., Covert, D., & Hegy, M. (2019). Natural Radiation in the Rocks, Soils, and Groundwater of Southern Florida with a Discussion on Potential Health Impacts. International Journal of Environmental Research and Public Health, 16(10), 1793. https://doi.org/10.3390/ijerph16101793

Ngoc, L. T. N., Park, D., & Lee, Y.-C. (2023). Human Health Impacts of Residential Radon Exposure: Updated Systematic Review and Meta-Analysis of Case–Control Studies. International Journal of Environmental Research and Public Health, 20(1), Article 1. https://doi.org/10.3390/ijerph20010097

Radon. (n.d.). Retrieved February 22, 2023, from https://www.who.int/news-room/fact-sheets/detail/radon-and-health

Reddy, A., Conde, C., Peterson, C., & Nugent, K. (2022). Residential radon exposure and cancer. Oncology Reviews, 16(1), 558. https://doi.org/10.4081/oncol.2022.558

Riudavets, M., Garcia de Herreros, M., Besse, B., & Mezquita, L. (2022). Radon and Lung Cancer: Current Trends and Future Perspectives. Cancers, 14(13), Article 13. https://doi.org/10.3390/cancers14133142

Schwela, D., & Kotzias, D. (2005). Pollution, Air Indoor. In Encyclopedia of Toxicology (pp. 475–489). Elsevier. https://doi.org/10.1016/B0-12-369400-0/00780-8

Stanley, F. K. T., Irvine, J. L., Jacques, W. R., Salgia, S. R., Innes, D. G., Winquist, B. D., Torr, D., Brenner, D. R., & Goodarzi, A. A. (2019). Radon exposure is rising steadily within the modern North American residential environment, and is increasingly uniform across seasons. Scientific Reports, 9(1), Article 1. https://doi.org/10.1038/s41598-019-54891-8

Tong, J., Qin, L., Cao, Y., Li, J., Zhang, J., Nie, J., & An, Y. (n.d.). Environmental Radon Exposure and Childhood Leukemia. Retrieved February 23, 2023, from https://www-tandfonline-com.libproxy1.nus.edu.sg/doi/epdf/10.1080/10937404.2012.689555?needAccess=true&role=button

US EPA, O. (2014, August 14). Health Risk of Radon [Overviews and Factsheets]. https://www.epa.gov/radon/health-risk-radon

Vi), N. R. C. (US) C. on H. R. of E. to R. (BEIR. (1999). Public Summary: The Health Effects of Exposure to Indoor Radon. In Health Effects of Exposure to Radon: BEIR VI. National Academies Press (US). https://www.ncbi.nlm.nih.gov/books/NBK233259/

Vogeltanz-Holm, N., & Schwartz, G. G. (2018). Radon and lung cancer: What does the public really know? Journal of Environmental Radioactivity, 192, 26–31. https://doi.org/10.1016/j.jenvrad.2018.05.017

What is nuclear fallout?

Nuclear fallout refers to the condensation of radioactive material produced from the detonation of nuclear weapons (Centres for Disease Control and Prevention, 2018). The dominant lethal effects lasting up to weeks, and the subsequent fallout contamination lasting up to decades (MIT Press Reader, 2022). As fallout consists of particles, nuclear fallout is often carried over long distances through wind, extending to areas beyond the explosion site. These charged particles can then mix with atmospheric water droplets, soot, or dust (Science, 2020).

Dangers of nuclear fallout

1. Human impacts

The impacts of radioactive fallout are wide, with people become irradiated through several ways following a nuclear fallout event. These include inhaling fallout particles or absorbing radiation through physical contact with fallout particles, as well as through consuming contaminated food (Black et al., 2017). One of the more widely studied incidents include the radioactive contamination of milk – in which cows consuming contaminated grass, resulting in the excretion of iodine 131 in their milk. The ingestion of radioactive iodine 131 then resulted in high concentrations of radioactivity in the thyroid gland (Yamamoto, 2013), increasing the chances of thyroid cancer in humans. More recent studies include Markabayeva et al.’s (2018) study on the effects of fallout exposure due to nuclear weapons testing in Kazakhstan, which found that populations living near these test sites had a higher incidence of cardiovascular diseases due to fallout exposure. To date, radioactive fallout in Kazakhstan mostly stems from uranium extraction activities, with fallout effects remaining a public health concern in populations living near nuclear test sites (Markabayeva et al., 2018). For populations who received significant amounts of radioactive fallout directly on their skin, this resulted in skin “burns”, as seen in Marshallese populations following the Bravo nuclear test on the Marshall Islands (Simon et al., 2014).

2. Environmental impacts

According to the International Committee of the Red Cross ([ICRC], 2020), modern environmental modelling techniques have shown that the emission of nuclear fallout particles from the use of nuclear weapons can lead to atmospheric cooling and shorter growing seasons, resulting in food shortages. The release of soot would block out sunlight, resulting in not just a decrease in global temperatures, but also less rainfall due to reduced evaporation rates due to lower temperatures (Van Hoesen, 2019). This phenomenon has come to be known as a “nuclear winter” (Carter, 2023), which could result global starvation along with the contamination of soil and water near nuclear weapons detonation sites.

References

Black, S., Bütikofer, A., Devereux, P., & Salvanes, K. (2013). This Is Only a Test? Long-Run Impacts of Prenatal Exposure to Radioactive Fallout (No. w18987; p. w18987). National Bureau of Economic Research. https://doi.org/10.3386/w18987

Carter, J. (n.d.). No Sunny Days For A Decade, Extreme Cold And Starvation: ‘Nuclear Winter’ And The Urgent Need For Public Education. Forbes. Retrieved February 15, 2023, from https://www.forbes.com/sites/jamiecartereurope/2023/02/13/no-sunny-days-for-a-decade-extreme-cold-and-starvation-nuclear-winter-and-the-urgent-need-for-public-education/

CDC Radiation Emergencies | Frequently Asked Questions About a Nuclear Blast. (2022, April 8). https://www.cdc.gov/nceh/radiation/emergencies/nuclearfaq.htm

Perkins, S. (n.d.). Can nuclear fallout make it rain? Retrieved February 15, 2023, from https://www.science.org/content/article/can-nuclear-fallout-make-it-rain

Reader, T. M. P. (2022, March 2). The Devastating Effects of Nuclear Weapons. The MIT Press Reader. https://thereader.mitpress.mit.edu/devastating-effects-of-nuclear-weapons-war/

Simon, S. L., Bouville, A., Land, C. E., & Beck, H. L. (2010). RADIATION DOSES AND CANCER RISKS IN THE MARSHALL ISLANDS ASSOCIATED WITH EXPOSURE TO RADIOACTIVE FALLOUT FROM BIKINI AND ENEWETAK NUCLEAR WEAPONS TESTS: SUMMARY. Health Physics, 99(2), 105–123. https://doi.org/10.1097/HP.0b013e3181dc523c

Van Hoesen, S. (2023). Science of Environmental Effects of Nuclear War // Artifacts Journal. https://artifactsjournal.missouri.edu/2019/06/science-of-environmental-effects-of-nuclear-war/

Yamamoto, L. G. (2013). Risks and Management of Radiation Exposure. Pediatric Emergency Care, 29(9), 1016. https://doi.org/10.1097/PEC.0b013e3182a380b8

 

Radioactive waste products are generally classified into two broad categories – low-level waste (LLW) and high-level waste (HLW) , such as uranium till minings and spent nuclear reactor fuel respectively (Energy Information Administration, 2022). While the disposal of LLW is often deemed to be “straightforward and can be undertaken safely almost anywhere” (World Nuclear Association, 2023), HLW is usually first stored away for a certain period of time to allow the decay of radioactivity and heat before disposal (World Nuclear Association, 2023). As the management of HLW is significantly more challenging, this blog article will focus on the current measures used to store and dispose HLW, and the risks of pollution arising from the (mis)management of HLW.

Storage and disposal of high-level nuclear waste

High-level radioactive waste, such as spent nuclear fuel, is first stored temporarily in underground or surface storage tanks, large concrete bays, or water pools. For such radioactive waste materials to be permanently stored away, HLW must be completely isolated from the environment for at least 10 half-lives, which can range from centuries to hundreds of thousands of years (Saeb & Patchet, 2003).

The final disposal of HLW through storing it in a Deep Geological Repository (DGR) has been deemed as an internationally accepted method for managing high-level nuclear waste (Lopez-Fernandez et al., 2015). Additionally, DGR is also among the preferred options when handling the high-energy contents of HLW such as spent nuclear fuel. This first involves storing the HLW in special dry storage casks which consist of several barriers, each with a specific purpose (Kurniawan et al., 2022):

First barrier	Fuel pellet: resistant to high temperatures, does not dissolve in solutions
Second barrier	Fuel bundle: made out of corrosion-resistant materials to contain and isolate the fuel pellets
Third barrier	Used nuclear container: prevents radionuclides from escaping into the underground environment
Fourth barrier	Bentonite clay buffer box: isolates radionuclides which have escaped from the used nuclear container and acts as a water-resistant barrier

These containers are then stored deep within a stable geologic environment, usually around an average of 500m underground. The surrounding bedrock, or host rock—which acts as the fifth barrier—has to be of low permeability to ensure that the nuclear fuel remains isolated for prolonged periods (Nuclear Waste Management Organisation [NWMO], n.d.).

 

So… what’s the problem with nuclear waste disposal?

The amount of nuclear waste stemming from spent nuclear fuel is predicted to increase exponentially within the next 50 years, as shown in this graph below:

This then brings forth the issue of not just space constraints to store large quantities of spent nuclear fuel, but also the need to assess if current waste disposal methods are sufficient. While nuclear waste disposal is relatively well-established for LLW, Ojovan and Steinmetz (2022) argue that HLW disposal, even with the utilisation of DGRs, still remains challenging. These challenges often pertain to three main reasons: the need for constant safety monitoring, that the operation of DGRs is still relatively understudied, and that these repository sites require prolonged periods of geological stability:

Furthermore, while dry storage casks and DGRs appear to have multiple safeguards to ensure that HLW is properly stored away, trace amounts of more mobile radionuclides can still end up dispersed in rock-groundwater systems (Chapman & McCombie, 2003). This is due to the fact that as HLW containers are not completely resistant to corrosion (Kurniawan et al., 2022), radioactive waste leakages can still occur.

A notable example of a HLW leakage is the radioactive contamination at the Hanford Nuclear Reservation – the result of 67 out of 149 single shell tanks leaking a total of 1.9 million litres of radioactive waste. HLW at this site has been argued to have already migrated through the vadose zone, resulting in groundwater contamination (Ma et al., 2018). This is especially concerning given the many potential repercussions, such as the contamination of drinking water sources and the bioaccumulation of radionuclides within crops planted in contaminated soils. Furthermore, this leakage has also been projected to eventually reach the Columbia River (Washington State Department, n.d.), which would then magnify the extent of contamination significantly.

References

Bruno, J., Duro, L., & Diaz-Maurin, F. (2020). 13—Spent nuclear fuel and disposal. In M. H. A. Piro (Ed.), Advances in Nuclear Fuel Chemistry (pp. 527–553). Woodhead Publishing. https://doi.org/10.1016/B978-0-08-102571-0.00014-8

Chapman, N., & McCombie, C. (2003). Chapter 2 Safety and security issues in deep geological disposal. In Waste Management Series (Vol. 3, pp. 21–44). Elsevier. https://doi.org/10.1016/S0713-2743(03)80004-1

Department for Business, Energy & Industrial Strategy. (2014, July 24). Geological disposal of radioactive waste: A guide for communities. GOV.UK. https://www.gov.uk/guidance/managing-radioactive-waste-safely-a-guide-for-communities

Kurniawan, T. A., Othman, M. H. D., Singh, D., Avtar, R., Hwang, G. H., Setiadi, T., & Lo, W. (2022). Technological solutions for long-term storage of partially used nuclear waste: A critical review. Annals of Nuclear Energy, 166, 108736. https://doi.org/10.1016/j.anucene.2021.108736

Leaking tanks—Washington State Department of Ecology. (n.d.). Retrieved February 7, 2023, from https://ecology.wa.gov/Waste-Toxics/Nuclear-waste/Hanford-cleanup/Leaking-tanks

Lopez-Fernandez, M., Cherkouk, A., Vilchez-Vargas, R., Jauregui, R., Pieper, D., Boon, N., Sanchez-Castro, I., & Merroun, M. L. (2015). Bacterial Diversity in Bentonites, Engineered Barrier for Deep Geological Disposal of Radioactive Wastes. Microbial Ecology, 70(4), 922–935. https://doi.org/10.1007/s00248-015-0630-7

Ma, R., Zheng, C., & Liu, C. (2018). Groundwater Impacts of Radioactive Wastes and Associated Environmental Modeling Assessment. In R. A. Meyers (Ed.), Encyclopedia of Sustainability Science and Technology (pp. 1–12). Springer. https://doi.org/10.1007/978-1-4939-2493-6_203-3

Multiple-Barrier System. (n.d.). Retrieved February 6, 2023, from https://www.nwmo.ca/en/A-Safe-Approach/Facilities/Deep-Geological-Repository/Multiple-Barrier-System

Nuclear power and the environment—U.S. Energy Information Administration (EIA). (n.d.). Retrieved February 6, 2023, from https://www.eia.gov/energyexplained/nuclear/nuclear-power-and-the-environment.php

Ojovan, M. I., & Steinmetz, H. J. (2022). Approaches to Disposal of Nuclear Waste. Energies, 15(20), Article 20. https://doi.org/10.3390/en15207804

Powell, T. (2021, April 30). An underground tank in Washington is leaking gallons of radioactive chemical waste. https://www.cbsnews.com/news/hanford-nuclear-site-leaking-radioactive-chemical-waste/

Saeb, S., & Patchet, S. J. (2003). Radioactive Waste Disposal (Geology). In R. A. Meyers (Ed.), Encyclopedia of Physical Science and Technology (Third Edition) (pp. 633–641). Academic Press. https://doi.org/10.1016/B0-12-227410-5/00641-4

Yano, K. H., Mao, K. S., Wharry, J. P., & Porterfield, D. M. (2018). Investing in a permanent and sustainable nuclear waste disposal solution. Progress in Nuclear Energy, 108, 474–479. https://doi.org/10.1016/j.pnucene.2018.07.003

What Happened:

The Chernobyl disaster of April 1986 was the result of a flawed nuclear reactor design, coupled with inadequately trained personnel operating the reactors (World Nuclear Association, 2022). The Number Four RBMK reactor, which was designed without a precautionary containment structure, received a sudden power surge during a reactor systems test and was destroyed (United States Nuclear Regulatory Commission, 2022). This incident then caused a steam explosion and resultant fire that­ ultimately released large amounts of radioactive elements over large parts of the Soviet Union (International Atomic Energy Agency [IAEA], n.d.). 134 workers who were present onsite suffered acute radiation sickness immediately following the explosion, in which 28 of them died within the following months (Canadian Nuclear Safety Commission, 2022).

This incident led to 31 immediate deaths and exposed more than 600,000 liquidators—firefighters and clean-up workers—to dangerously high levels of radiation (United Nations, n.d.). Reports also indicated that 155,000km² of territory across Belarus, Russia, and Ukraine, along with 52,000km² were contaminated with long-lived radionuclides (United Nations, n.d.).

The population of Pripyat—a town with a population of more than 49,000—was evacuated 36 hours after the explosion, with an estimation of 200,000 people relocated as a result of the Chernobyl disaster (IAEA, n.d.). Till today, Pripyat remains an abandoned town, preserving Soviet elements in its architecture and environment.

After-effects of Chernobyl: Radiation-associated diseases

Decades after the Chernobyl disaster, many studies have established strong links between exposure to radiation and the development of cancer (Cardis & Hatch, 2011). To elaborate, exposure to iodine isotopes has been found to increase the likelihood of developing radiation-associated thyroid cancer (Saenko et al., 2011), especially . This observation has been supported by the huge onset of thyroid cancer in children and adults four years following the Chernobyl disaster, with around 13,000 children having been exposed to dangerously high levels of radiation (Petryna, 2004).

To date, radiation-associated thyroid cancer among children and adolescents still remains as the only direct adverse health consequence of the Chernobyl disaster (Abbott et al., 2007). However, the record of diseases of Chernobyl liquidators extends much further than just thyroid cancer:

Aside from the list of suspected radiation-associated diseases and illnesses, the exposure to ionizing radiation has been alleged to cause damage to hereditary structures. To elaborate, the frequency of irradiated parents having children with abnormal chromosomes is higher compared to children born in less contaminated areas across Russia, Ukraine, and Belarus (Yablokov, 2009). As such, this illustrates how the impacts of irradiation extend far beyond those who were located within the contaminated zones – children born to irradiated parents years after the Chernobyl catastrophe still continue to bear the harmful health impacts of radiation exposure.

In recent years, however, more researchers have begun disputing the effects of children born to highly irradiated parents, citing that “even when people were exposed to relatively high doses of radiation – when compared to background radiation – it had no effect on their future children” (Gill, 2021).

What about Chernobyl today?

The Chernobyl Exclusion Zone (CEZ) has grown to become a popular tourist site, with highly regulated tours issuing Geiger counters to tourists and letting them wander through abandoned towns, and interacting with the dead zone residents (Stone, 2013). This has often been cited as part of the wider phenomenon of exploring disaster cites, where tourist activity continues to contribute to “difficult heritage” of the CEZ (Banaszkiewicz et al., 2017).

 

References

Abbott, P., Wallace, C., & Beck, M. (n.d.). Chernobyl: Living with risk and uncertainty. https://doi.org/10.1080/13698570600677167

Backgrounder on Chernobyl Nuclear Power Plant Accident. (n.d.). NRC Web. Retrieved January 30, 2023, from https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/chernobyl-bg.html

Banaszkiewicz, M., Kruczek, Z., & Duda, A. (2017). The Chernobyl Exclusion Zone as a Tourist Attraction: Reflections on the Turistification of the Zone. Folia Turistica / Akademia Wychowania Fizycznego Im. B. Czecha w Krakowie, nr 44, 145–169. https://doi.org/10.5604/01.3001.0010.8736

Biological Citizenship: The Science and Politics of Chernobyl-Exposed Populations. (n.d.). https://doi.org/10.1086/649405

Borys, C. (2017, January 30). A vast new tomb for the most dangerous waste in the world. Retrieved February 2, 2023, from https://www.bbc.com/future/article/20170101-a-new-tomb-for-the-most-dangerous-disaster-site-in-the-world

Chernobyl | Chernobyl Accident | Chernobyl Disaster—World Nuclear Association. (n.d.). Retrieved January 30, 2023, from https://world-nuclear.org/information-library/safety-and-security/safety-of-plants/chernobyl-accident.aspx

Dolzhenko, S. (2020, February 4). Tourists flock to Chernobyl – in pictures. The Guardian. http://www.theguardian.com/environment/gallery/2020/feb/04/tourists-flock-to-chernobyl-in-pictures

Frequently Asked Chernobyl Questions. (2016, November 7). [Text]. IAEA. https://www.iaea.org/newscenter/focus/chernobyl/faqs

Full article: Chernobyl: Living with risk and uncertainty. (n.d.). Retrieved February 1, 2023, from https://www-tandfonline-com.libproxy1.nus.edu.sg/doi/full/10.1080/13698570600677167

Gill, V. (2021, April 22). Chernobyl radiation damage “not passed to children.” BBC News. https://www.bbc.com/news/science-environment-56846728

Hussain, C. M., & Keçili, R. (2020). Chapter 1—Environmental pollution and environmental analysis. In C. M. Hussain & R. Keçili (Eds.), Modern Environmental Analysis Techniques for Pollutants (pp. 1–36). Elsevier. https://doi.org/10.1016/B978-0-12-816934-6.00001-1

Savage, N. (2022, February 25). Russia took control of the Chernobyl nuclear site in Ukraine. What does that mean? Retrieved February 1, 2023, from https://cen.acs.org/safety/Russia-took-control-Chernobyl-nuclear-site-in-Ukraine-What-does-that-mean/100/web/2022/02

Saenko, V., Ivanov, V., Tsyb, A., Bogdanova, T., Tronko, M., Demuidchik, Y., & Yamashita, S. (2011). The Chernobyl Accident and its Consequences. Clinical Oncology, 23(4), 234–243. https://doi.org/10.1016/j.clon.2011.01.502

Viel, J. F., Curbakova, E., Dzerve, B., Eglite, M., Zvagule, T., & Vincent, C. (1997). Risk factors for long-term mental and psychosomatic distress in Latvian Chernobyl liquidators. Environmental Health Perspectives, 105 Suppl 6(Suppl 6), 1539–1544. https://doi.org/10.1289/ehp.97105s61539

Yablokov, A. V. (2009). 5. Nonmalignant diseases after the Chernobyl catastrophe. Annals of the New York Academy of Sciences, 1181, 58–160. https://doi.org/10.1111/j.1749-6632.2009.04826.x

Radioactive pollution – also known as radioactive contamination, refers to the release of radioactive substances into the environment (Hussain & Keçili, 2020). Radionuclides, which emit beta particles and gamma rays during radioactive decay, are often the main culprit of radioactive pollution (Posudin, 2014). While most might reckon that the release of radionuclides predominantly occur during nuclear-related disasters, such as the use of nuclear weapons or nuclear power plant accidents, the presence of radionuclides—and by extension, the sources of radiation—are rather commonplace as shown in the table below:

To further illustrate this, this blog article will expand on the two categories of radionuclides, as well as the sources and impacts of being exposed to radionuclides.

Naturally occurring radionuclides

Naturally occurring radionuclides are often found in environmental matrices such as soils, water, and air (Ojovan & Lee, 2005). Apart from these sources, phenomena such as volcanic activity (Perkins, 2019) also emit radioactive particles into the environment. In a nutshell, this group of radionuclides consists of primordial radioactive elements in the earth’s crust, their radioactive decay products, and radionuclides produced by cosmic-radiation interactions (National Academic Press (US), 1999). Among the many naturally occurring radionuclides is a particular radionuclide that has garnered increasing scrutiny due to its vast negative impacts – radon.

Exposure to radon (mostly ²²²Rn)—despite being a naturally occurring radionuclide—and its decay products, has raised public health concerns due to its high prevalence in indoor spaces and carcinogenic properties (World Health Organisation, 2023). To elaborate, Yousef and Zimami (2019) posit that exposure to radon makes up more than 70% of the total annual radioactive dose received by people, with radon exposure contributing to approximately half of the total effective dose equivalent received from natural and anthropogenic radioactivity.

Anthropogenic radionuclides

The release of anthropogenic radionuclides largely stems from radioactive waste and contamination, which are often resultant of the development of nuclear power, nuclear accidents, and the operation of nuclear power plants (Qiao & Nielsen, 2019). To date, the majority of radioactivity stems from high-level waste and spent nuclear fuel, with nuclear accidents contributing to the highest amount of radioactive emissions (Hu et al., 2010).

The prevalence of anthropogenic radionuclides can also bring forth radioactive transfer through food chains due to the contamination of soils and water sources (IAEA, 2009), in which the radionuclides then transfer to cultivated crops. This phenomenon has been attributed to the deposition of radioactive fallout due to rampant nuclear weapons testing, which resulted in the dispersal of radioactive gases and particles (Centres for Disease Control and Prevention [CDC], 2014). Exposure to radioactive fallout can manifest in several ways:

Nuclear accidents, such as the Chernobyl nuclear plant disaster, can also give contribute to significant deposition of radionuclides which can ultimately result in the radioactive contamination of food as well (Bundesamt für Strahlenschutz, 2022).

As such, while such forms of radiation exposure may not be as intense as those compared to nuclear disasters, the prolonged inhalation and consumption of radiation through contaminated air and food still remain a cause for concern. The following blog posts will dive deeper into the impacts of radioactive pollution, and will also touch on several case studies related nuclear disasters.

 

References

Barkhudarov, R. M., Knizhnikov, V. A., Novikova, N. Y., & Petukhova, E. V. (1988). Effect of Local Conditions on Coefficient of Radionuclide Transfer Through Food Chains. In J. H. Harley, G. D. Schmidt, & G. Silini (Eds.), Radionuclides in the Food Chain (pp. 133–135). Springer. https://doi.org/10.1007/978-1-4471-1610-3_11

HotSpot before and after: Lake Karachay in the Russian Federation  filled with radioactive waste is the cause of cancer. (n.d.). Retrieved January 26, 2023, from https://www.ecohubmap.com/hot-spot/lake-karachay-become-the-most-polluted-spot-on-earth/5g4uyml7kr620m

Hu, Q.-H., Weng, J.-Q., & Wang, J.-S. (2010). Sources of anthropogenic radionuclides in the environment: A review. Journal of Environmental Radioactivity, 101(6), 426–437. https://doi.org/10.1016/j.jenvrad.2008.08.004

Hussain, C. M., & Keçili, R. (2020). Chapter 1—Environmental pollution and environmental analysis. In C. M. Hussain & R. Keçili (Eds.), Modern Environmental Analysis Techniques for Pollutants (pp. 1–36). Elsevier. https://doi.org/10.1016/B978-0-12-816934-6.00001-1

Materials, N. R. C. (US) C. on E. of E. G. for E. to N. O. R. (1999). Natural Radioactivity and Radiation. In Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. National Academies Press (US). https://www.ncbi.nlm.nih.gov/books/NBK230654/

Ojovan, M. I., & Lee, W. E. (2005). Chapter 5—Naturally Occurring Radionuclides. In M. I. Ojovan & W. E. Lee (Eds.), An Introduction to Nuclear Waste Immobilisation (pp. 43–52). Elsevier. https://doi.org/10.1016/B978-008044462-8/50007-7

Posudin, Y. (2014). Chapter 36—Radioactive Pollution. (2014). In Methods of Measuring Environmental Parameters (pp. 380–384). John Wiley & Sons, Ltd. https://doi.org/10.1002/9781118914236.ch36 

Radioactive Fallout from Global Weapons Testing: Home | CDC RSB. (2022, December 23). https://www.cdc.gov/nceh/radiation/fallout/rf-gwt_home.htm

 Radon. (2023, January 23). Retrieved January 25, 2023, from https://www.who.int/news-room/fact-sheets/detail/radon-and-health

Tarakanov, V. (2022, June 1). What is Radon and How are We Exposed to It? [Text]. IAEA. https://www.iaea.org/newscenter/news/what-is-radon-and-how-are-we-exposed-to-it

 What radionuclides can be found in food? (2022, April 1). Federal Office for Radiation Protection. Retrieved January 26, 2023, from https://www.bfs.de/EN/topics/ion/environment/foodstuffs/introduction/introduction_node.html

Yousef, A. M. M., & Zimami, K. (2019). Indoor radon levels, influencing factors and annual effective doses in dwellings of Al-Kharj City, Saudi Arabia. Journal of Radiation Research and Applied Sciences, 12(1), 460–467. https://doi.org/10.1080/16878507.2019.1709727