农田“水-土-气”界面氨挥发关键过程的影响机制与区域模拟

Ammonia (NH₃) volatilized from the land to the atmosphere accelerates the formations of ammonium aerosols. It’ concentration has been persistently increasing in the global atmosphere due largely to its emissions from agricultural soils. Quantification of NH₃ volatilization loss and formulation effective measures are urgently needed to guide stakeholders and policymakers on minimizing NH₃ emission from agriculture. However, cropland NH₃ volatilization estimates in China could be more than twice the difference from one study to another. In-depth understanding about the NH₃ emission process on water-air and soil-air interface could reduce the uncertainty. Here, we will develop laboratory experimentations and field observations to explore the relationship between the key parameters of NH₃ emission process and related environmental factors. Based on these experiments, we will improve the process-based model (ORCHIDEE-CROP) to achieve better simulation results on NH₃ transfer process, agricultural measures and crop planting systems (paddy fields and upland). Overall this project will broaden our knowledge of the interaction between environment change and NH₃ emission. And the improved process-based model could provide mitigation strategies for enhancing crop yield with lower NH₃ emission in China.

氨是大气二次气溶胶形成的重要前驱物，其浓度持续增高危害着生态环境与人类健康。农田排放是主要贡献源，基于过程模型手段估算其区域排放量，设计氨减排措施具有重要的实际意义。但现有研究对于氨在水-土-气界面的扩散过程存在认识偏差，导致模型模拟结果存在较大不确定性。包括对水-气界面上调控水相氨向气相氨转化的关键参数(亨利常数与活度系数)，土-气界面上的土壤氨扩散系数及其环境敏感性缺少深入理解。本项目将结合室内实验与大田观测，解析水-土-气界面氨挥发过程关键参数的影响因素与调控机制；提高现有模型对氨扩散过程、水肥管理措施和作物类型(水田与旱地)的模拟精度；优化后的生态系统模型(ORCHIDEE-CROP)可从粮食安全与环境友好的角度提出区域尺度的氨减排策略。本项目有利于增进理解气候变化、水肥措施对氨挥发过程的作用机制，在作物产量与氨排放量之间找到水肥管理的平衡点，为制定农田氨减排策略提供科学依据。

氨是大气二次气溶胶形成的重要前驱物，其浓度持续增高危害着生态环境与人类健康。农田排放是主要贡献源，基于过程模型手段估算其区域排放量，设计氨减排措施具有重要的实际意义。但现有研究对于氨挥发过程存在认识偏差，导致模型模拟结果存在较大不确定性。本研究围绕“农田氨排放及其影响机制”这一重要研究热点开展了系列研究。在观测、数据、模型、模拟与评估等方面都取得了一系列成果。包括：（1）开展了室内控制实验及野外实验解析水-土-气界面氨挥发过程的关键参数及其影响因素；（2）整合实验观测数据及文献调研数据，优化了现有农田氨挥发模拟模型，模拟了全球氨挥发通量，提高模型对氨挥发过程、农艺管理措施、作物类型的模拟精度；（3）检测中国氨排放的时空格局及归因；（4）预测了未来最具减排潜力的作物与重点区域。在项目的支持下发表SCI论文4篇，EI论文1篇，中文核心1篇。