题目：长三角城市高氮湿沉降通量及其主要来源
High atmospheric wet nitrogen deposition and major sources in two cities of Yangtze River Delta
主讲人：2019级博士生 陈志立
时间：10月20日（周四）中午12:00
地点：16教221会议室
摘要：高氨气和氮氧化物排放与城市严重的空气污染密切相关，过量氮沉降对生态系统造成负面影响。然而，在许多地区，氮沉积通量及其来源与城市化之间是否存在关系尚不清楚。2017年7月到2018年6月，在长三角的南京和扬州两个城市的市区和郊区同步观测氮湿沉降通量，并利用扩散法测定了雨水中铵态氮和硝态氮的氮稳定同位素。研究发现，中等城市的扬州氮湿沉降量高于大城市南京，市区的氮湿沉降量高于郊区。氮稳定同位素示踪表明，长三角城市地区高氮湿沉降主要来自于燃烧相关的氨排放（62%–65%）和非化石燃料燃烧的氮氧化物排放（50%–63%）。这项研究揭示了长三角城市地区高氮沉降量以及燃烧相关NH3排放和非化石燃料NOx排放的重要性，为减排和空气污染治理提供一定参考。
High NH3 and NOx emissions are related to serious air pollution in urban areas and the negative impacts of excessive reactive N deposition on many ecosystems. However, whether there is a relationship between N deposition rates and their sources with urbanization or not remains unclear in many areas. Here, we investigated the wet N deposition rates from July 2017 to June 2018 at two urban and two suburban sites in the Yangtze River Delta. The δ15N values of precipitation NH4+ and NO3– were measured, and major sources were analyzed using a Bayesian isotope mixing model. Wet N deposition rates were higher in Yangzhou than those in Nanjing, and were higher at urban sites than those at suburban sites. For NH4+, combustion-related NH3 sources (62%–65%) contributed more than volatilization NH3 sources (35%–38%). For NO3–, non-fossil fuel NOx sources (50%–63%) were comparable to fossil fuel NOx sources (37%–50%). This study evidenced high N deposition rates and the importance of combustion-related NH3 emissions and non-fossil fuel NOx emissions in city areas of the Yangtze River Delta, which is significant for air pollution control and emission reduction policy formulation.
