In response to Pollutant de Jure’s question on what are some other pollutants that can be produced from livestock production, I thought that it will be good to dedicate a post to answer the question.  As such, thank you for the comments that you have posted!

Questions from Pollutant de Jure: What other pollutants can be produced from livestock production? Are these odour-producing compounds from livestock and manure greenhouse gases as well?

To refresh our minds a little, in the first post about livestock air pollution, we mainly covered on methane (CH4) and nitrous oxides (NOx) due to the processes of enteric fermentation and nitrification and denitrification of nitrogen from livestock manure. We also evaluated their role on global warming as potent greenhouse gases (GHG) with Global Warming Potential (GWP) values much higher than that of carbon dioxide (CO2) and hence the reason why they are of concern when it comes to global warming issues. On top of that, in the last few posts, we also explored on livestock emissions consisting of particulate matter (PM), endotoxins, micro-organisms and even zoonotic pathogens that may pose certain health risks to both farmers and possibly neighbouring residents.

To add on to what we investigated so far, there are other pollutants that are of concern as well, particularly ammonia (NH3) and hydrogen sulphide (H2S). Both NH3 and H2S contributes heavily to atmospheric pollution (Shi, Sun, Lu, Xi and Zhao, 2019). Livestock production is responsible for 64% of total global anthropogenic NH3 emissions, and in the case of the Netherlands, dairy farm contributed to about 50% of total NH3 emissions (Shi, Sun, Lu, Xi and Zhao, 2019). This number is projected to increase as well with the increase in demand for meat consumption and dairy products globally. Not only are they of concern in terms of atmospheric pollution, they are also key odour-producing gases from livestock farms. These gases are irritants that produce distinctive odours resembling that of ‘rotten eggs’ and hence explains why livestock and their manure often smells (that bad).

Ammonia (NH3)

NH3 is a significant odorous gas that is emitted from livestock production, typically from the decomposition of organic matters such as livestock manure as well as from enteric fermentation. When released, it releases a sharp pungent smell that contributes to odour nuisance as a result of livestock and their manure. However, (much to my own surprise) NH3 has a GWP value of 0 and therefore it does not contribute to ozone depletion and global warming (Ammonia21, n.d.). In fact, it is a natural occurring gas present in the atmosphere.

Atmospheric NH3, though not a GHG, is a significant pollutant on ecosystems typically in the form of acid deposition. This is often in the formation of acid rain resulting in the deposition of acidified rain into surface water bodies via precipitation and even lead to eutrophication (algae blooms) (Jongebreur and Voorburg, 1992). As such, this could also bring our attention to how livestock production also results in water pollution in the form of acid rain even though it may not be a GHG contributing to global warming.

 

Hydrogen Sulphide (H2S)

Although H2S is not a GHG and hence we are (slightly) less concerned as to how it will contribute to global warming, there is still a need to pay close attention to the health implications of this odorous gas. H2S emitted is formed by anaerobic decomposition of sulphur-containing organic compounds and is a dominant gas in animal confinement facilities and manure storages (MSU Extension, 2011). In fact, H2S is one the most dangerous gas as there have been reports of this gas being responsible for the death of animals and farmers as a result of chronic exposure (Shi, Sun Lu, Xi and Zhao, 2019). Hence, H2S play a key role when it comes to health impacts of livestock pollutants.

In addition, though it is not a GHG, H2S emissions also contributes to the sulphur compounds present in the atmosphere which in turn react with other compounds to form secondary aerosols such as sulphate aerosol, thus becoming secondary pollutants (Shi, Sun, Lu, Xi and Zhao, 2019). Generally, sulphate aerosols are known to have a cooling effect on the Earth as they can increase the Earth’s albedo (Fig.1), though this effect may be counterbalanced by effects of other GHG emissions thart exacerbates global warming (Mendelsohn, Schlesinger and Williams, 2001; NASA Earth Observatory, 2010).


Fig. 1 Light vs dark surface and its albedo effect, whereby high albedo reflects off 80% of incoming radiation and low albedo reflects off only 10% of incoming radiation. Obtained from: https://climate.ncsu.edu/edu/Albedo

 

I hope that this post will provide a bit more insight into the livestock pollutants and its relevance to global warming and climate change. Thank you for reading and catch you soon!

 

Detective Out,

Linying

 

References

Ammonia21. (n.d.). FAQ. Ammonia21. Retrieved from: https://www.ammonia21.com/knowledge/faq

Jongerbreur, A. A. and Voorburg, J. H. (1992). The role of ammonia in acidification. Perspectives for the prevention and reduction of emissions from livestock operations. Studies in Environmental Science, 50, 55-64. Retrieved from: https://www.sciencedirect.com/science/article/pii/S0166111608701018

Mendelsohn, R., Schlesinger, M. and Williams, L. (2001). The climate impacts of sulfate aerosols. Integrated Assessment, 2, 111-122. Retrieved from: https://link.springer.com/article/10.1023/A:1013319100965

Michigan State University Extension. (2011). The impact of ammonia and hydrogen sulfide emissions from animal agriculture. MSU Extension. Retrieved from: https://www.canr.msu.edu/news/the_impact_of_ammonia_and_hydrogen_sulfide_emissions_from_animal_agricultur

NASA Earth Observatory. (2010). Aerosols and incoming sunlight (direct effects). NASA. Retrieved from: https://earthobservatory.nasa.gov/features/Aerosols/page3.php#:~:text=Aerosols%20play%20an%20important%20role%20in%20Earth’s%20climate.&text=Darker%20aerosols%20can%20absorb%20significant,but%20also%20shading%20the%20surface.

Shi, Z., Sun, X., Lu, Y., Xi, L. and Zhao, X. (2019). Emissions of ammonia and hydrogen sulfide from typical dairy barns in central China and major factors influencing the emissions. Sci Rep 9(13821). Retrieved from: https://doi.org/10.1038/s41598-019-50269-y