Key Laboratory of Agro-Ecological Processes in Subtropical Regions, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria 3010, Australia.
Sci Rep. 2016 Sep 7;6:32793. doi: 10.1038/srep32793.
Intensive cattle feedlots are large emission sources of ammonia (NH3), but NH3 deposition to the landscape downwind of feedlots is not well understood. We conducted the first study in Australia to measure NH3 dry deposition within 1 km of a commercial beef cattle feedlot in Victoria. NH3 concentrations and deposition fluxes decreased exponentially with distance away from the feedlot. The mean NH3 concentrations decreased from 419 μg N m(-3) at 50 m to 36 μg N m(-3) at 1 km, while the mean NH3 dry deposition fluxes decreased from 2.38 μg N m(-2) s(-1) at 50 m to 0.20 μg N m(-2) s(-1) at 1 km downwind from the feedlot. These results extrapolate to NH3 deposition of 53.9 tonne N yr(-1) in the area within 1 km from the feedlot, or 67.5 kg N ha(-1) yr(-1) as an area-weighted mean, accounting for 8.1% of the annual NH3-N emissions from the feedlot. Thus NH3 deposition around feedlots is a significant nitrogen input for surrounding ecosystems. Researches need be conducted to evaluate the impacts of NH3 deposition on the surrounding natural or semi-naturals ecosystems and to reduce N fertilizer application rate for the surrounding crops by considering nitrogen input from NH3 deposition.
集约化牛养殖场是氨（NH3）的大型排放源，但养殖场下风处的 NH3 沉积对景观的影响还不太清楚。我们在澳大利亚进行了首次研究，测量了维多利亚州一个商业肉牛养殖场下风处 1 公里范围内的 NH3 干沉积。NH3 浓度和沉积通量随距离养殖场的增加而呈指数下降。NH3 浓度平均值从 50 米处的 419μg N m(-3)下降到 1 公里处的 36μg N m(-3)，而 NH3 干沉积通量平均值从 50 米处的 2.38μg N m(-2) s(-1)下降到 1 公里处的 0.20μg N m(-2) s(-1)。这些结果推断出，在距养殖场 1 公里范围内，NH3 的沉积量为 53.9 吨 N yr(-1)，或者作为面积加权平均值为 67.5kg N ha(-1) yr(-1)，占养殖场 NH3-N 排放量的 8.1%。因此，养殖场周围的 NH3 沉积是周围生态系统的一个重要氮素输入。需要进行研究，以评估 NH3 沉积对周围自然或半自然生态系统的影响，并通过考虑 NH3 沉积的氮素输入来降低周围作物的氮肥施用量。
