Welcome back dear foodies!

We have already discussed extensively on how livestock causes air pollution and its detriments on our environment and human beings, let us now look at how livestock also causes water pollution.

Improper Livestock Manure Management

Surface Water Contamination

Livestock-induced water pollution is often a result of improper management of livestock manure. This can happen either directly through drainage of untreated manure into surface water bodies or indirectly through runoffs. This can also take place in the case of spillage of manure storage facilities or as a result of excessive and extended period rain leading to overland run-offs (Wang, 2005). When nutrients from livestock manure run off into surface water bodies, these nutrients stimulate the growth of microorganisms and algae blooms, which depletes the oxygen available in the water bodies as they decomposes, resulting in the loss of biodiversity such as fish kills (National Ocean Service, 2020). This process is known as eutrophication (Fig.1) Another major source of excess nutrients comes from the use of fertilisers on agricultural crops, in which we will be focusing on in the Agriculture section.

Fig. 1 Algae bloom in lake. Obtained from: https://www.theguardian.com/environment/2020/jan/04/lethal-algae-blooms-an-ecosystem-out-of-balance

 

Groundwater Contamination

Not only does improper manure management lead to contamination of surface water, manure or liquid manure can also seep into groundwater aquifers thereby degrading groundwater sources (PCIFAP, n.d.). This is especially as a result of land application of manure, which facilitates contaminants to leech into underground water sources. Both stored manure of land-applied manure has the potential to increase the concentration of nitrates in the ground. As nitrates percolate into the soil, not all of it is absorbed for plant use. As such, remaining nitrates can seep through and degrades underground water sources (NDSU, 2017). These underground water sources may be water sources for human use as well, as such there is a direct implication on the risks posed to humans.

When the concentrations of nitrates in groundwater is excessive, it can also lead to nitrate poisoning. Moreover, manure that was leaked into water bodies may also carry pathogens and antimicrobial resistance (AMR) bacteria, heightening the risks associated with livestock-induced water pollution (Oun, Kumar, Harrigan, Angelakis and Xagoraraki, 2014).

As mentioned in the posts about air pollution, we saw that livestock emissions may carry zoonotic pathogens attached to airborne particles that can result in the transmission of infectious diseases from animal to human population. Whereas in this case, infections occur through waterborne diseases.

Increasingly, studies have found that there is an increase in the concentration of antibiotic resistance genes (ARGs) in livestock manure and its surrounding environments (Xu et al., 2020). Antibiotics are increasingly used in livestock production in order to promote growth of animals and control animal infections, which in turn maximises efficiency to meet growing demands. Moreover, between 30% – 90% of the antibiotics dose is discharged with animal excreta (PCIFAP, n.d.). As a result, antimicrobial resistant (AMR) bacteria can be spread through livestock manure onto our environments, leaving behind residues of antibiotics which could severely contaminate our ecosystem and pose potential threats to human beings (Xu et al., 2020).

 

To conclude, we see that not only does improper management of manure leads to surface water contamination, it also may cause groundwater contamination, as well as negative implications on both our environment and human population.

In this next post, Wen Hong will bring us through a clearer view on antibiotics!

That is all for today, thank you!

 

Detective Out,

Linying

 

References

National Ocean Service. (2020). What is eutrophication? National Oceanic and Atmospheric Administration. Retrieved from: https://oceanservice.noaa.gov/facts/eutrophication.html

NDSU. (2017). Environmental implications of excess fertilizer and manure on water quality. North Dakota State University Publications. Retrieved from: https://www.ag.ndsu.edu/publications/environment-natural-resources/environmental-implications-of-excess-fertilizer-and-manure-on-water-quality#:~:text=When%20manure%20or%20commercial%20fertilizers,and%20other%20aquatic%20species%20suffocate.

Oun, A., Kumar, A., Harrigan, T., Angelakis, A. and Xagoraraki, I. (2014). Effects of biosolids and manure application on microbial water quality in rural areas in the US. Water, 6(12), 3701-3723. Retrieved from: https://www.mdpi.com/2073-4441/6/12/3701/htm

PCIFAP. (n.d.). Environmental impact of industrial farm animal production. Pew Commission on Industrial Farm Animal Production. Retrieved from: https://www.lclark.edu/live/files/6699-environmental-impact-of-industrial-farm-animal

Wang, X. (2005). Diffuse pollution from livestock production in China. Chinese Journal of Geochemistry, 24(2), 189-193. Retrieved from:

Xu et al. (2020). Antibiotic resistance genes in different animal manures and their derived organic fertilizer. Environmental Sciences Europe, 32(102). Retrieved from: https://link.springer.com/article/10.1186/s12302-020-00381-y#citeas