Abstract
Intensive livestock production has been increasing, and has resulted in the emission of more than seven teragram per year of ammonia (NH3) in China in recent years. However, little is known about the fate of the emitted NH3, especially the dry deposition of NH3 in the environs of intensive animal farms. In this study, the spatial and temporal variations of NH3 deposition in the environs of an intensive fattening pig farm were investigated in the central south of China. NH3 concentrations were measured at sites situated 50, 100, 200, 300, and 500 m in the downwind direction from the farm each month from July 2018 to June 2019. The NH3 deposition was calculated based on a bidirectional NH3 exchange model. The monthly NH3 emissions from the pig farm were estimated based on the breeding stock. The annual average NH3 concentrations ranged from 1200 to 14 μg m−3 at the downwind sites within 500 m of the pig farm, exhibiting exponential decay as distance increased. Strong seasonality in NH3 deposition was observed, with the highest season being in the summer and lowest in the winter, and air temperature was found to be an important factor affecting this seasonal variation. The estimated monthly total dry deposition within 500 m of the pig farm ranged from 92 to 1400 kg NH3–N mo−1, which accounted for 4.1%–14% of the total monthly NH3 emissions from the pig farm. The estimated total NH3 emissions and NH3 deposition from the pig farm were 63 000 kg NH3–N yr−1 and 5400 kg NH3–N yr−1, respectively, with the annual average ratio of NH3 deposition to NH3 emission being 8.6%. This study found NH3 deposition around intensive pig farms is high, and determined it as a significant fate of the NH3 emitted from pig farms.
Highlights
NH3 is a highly reactive and alkaline gas with detrimental human health and ecological impacts (Gourley et al 2012, Zhang et al 2020)
The daily NH3 emissions ranged from 25 kg NH3–N d−1 to 400 kg NH3–N d−1, with an average of 173 kg NH3–N d−1
This study investigated NH3 concentration measurements at 50, 100, 200, 300, and 500 m downwind of an intensive fattening pig farm with an average stock of 8900 animals in the central south of China from July 2018 to June 2019
Summary
NH3 is a highly reactive and alkaline gas with detrimental human health and ecological impacts (Gourley et al 2012, Zhang et al 2020). It originates from both natural and anthropogenic sources, with agriculture being its major source (Van Damme et al 2018, Guo et al 2020, Mueller and Lassaletta 2020). The excess N input via atmospheric NH3 deposition has noticeably detrimental effects on ecosystems, including soil acidification (Shen et al 2018), N2O emission enhancement (Xie et al 2018), and eutrophication and acidification of surface and ground water (Scudlark et al 2005, Zhan et al 2017). NH3 deposition has become an important source of N content in surface water for the lakes, and may trigger the eutrophication and acidification of surface water (Scudlark et al 2005, Zhai et al 2009, Zhan et al 2017)
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