Institute of Integrated Watershed Management, Sino-France Institute of Earth Systems Science, Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University , Beijing, 100871, P.R. China.
Laboratoire des Sciences du Climat et de l'Environnement, CEA CNRS UVSQ , 91191 Gif-sur-Yvette, France.
Environ Sci Technol. 2016 Jan 19;50(2):564-72. doi: 10.1021/acs.est.5b03156. Epub 2016 Jan 7.
Ammonia (NH3) released to the atmosphere leads to a cascade of impacts on the environment, yet estimation of NH3 volatilization from cropland soils (VNH3) in a broad spatial scale is still quite uncertain in China. This mainly stems from nonlinear relationships between VNH3 and relevant factors. On the basis of 495 site-years of measurements at 78 sites across Chinese croplands, we developed a nonlinear Bayesian tree regression model to determine how environmental factors modulate the local derivative of VNH3 to nitrogen application rates (Nrate) (VR, %). The VNH3-Nrate relationship was nonlinear. The VR of upland soils and paddy soils depended primarily on local water input and Nrate, respectively. Our model demonstrated good reproductions of VNH3 compared to previous models, i.e., more than 91% of the observed VR variance at sites in China and 79% of those at validation sites outside China. The observed spatial pattern of VNH3 in China agreed well with satellite-based estimates of NH3 column concentrations. The average VRs in China derived from our model were 14.8 ± 2.9% and 11.8 ± 2.0% for upland soils and paddy soils, respectively. The estimated annual NH3 emission in China (3.96 ± 0.76 TgNH3·yr(-1)) was 40% greater than that based on the IPCC Tier 1 guideline.
氨气（NH3）排放到大气中会导致一系列环境影响，但在中国，对农田土壤中氨气挥发量（VNH3）的广泛空间尺度的估计仍然非常不确定。这主要是由于 VNH3 与相关因素之间存在非线性关系。在对中国农田 78 个地点的 495 个站点年的测量基础上，我们开发了一种非线性贝叶斯树回归模型，以确定环境因素如何调节 VNH3 对氮施用量（Nrate）的局部导数（VR，%）。VNH3-Nrate 关系是非线性的。旱地土壤和稻田土壤的 VR 主要取决于当地的水分输入和 Nrate。与以前的模型相比，我们的模型对 VNH3 的再现性更好，即在我国站点，超过 91%的观察到的 VR 方差，而在我国以外的验证站点，有 79%的观察到的 VR 方差。中国观测到的 VNH3 空间格局与基于卫星的 NH3 柱浓度估计值吻合较好。我们的模型估计，中国旱地土壤和稻田土壤的平均 VR 分别为 14.8±2.9%和 11.8±2.0%。根据 IPCC 第一级指南，中国每年估计的 NH3 排放量（3.96±0.76TgNH3·yr-1）比该指南高出 40%。
