西沙永兴岛大气沉降硝酸盐来源的氮氧同位素示踪研究

项目名称： 西沙永兴岛大气沉降硝酸盐来源的氮氧同位素示踪研究

项目编号： No.41203015

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 地球化学

项目作者： 肖红伟

作者单位： 中国科学院南海海洋研究所

项目金额： 25万元

中文摘要： 已有大气硝酸盐沉降研究主要集中在内陆或近海区域，本研究以远离大陆的南海西沙永兴岛为研究区域，对大气沉降硝盐酸进行长期监测。用同位素地球化学和大气化学的基本原理和研究手段，通过分析大气沉降离子组成和硝酸盐氮氧同位素组成的季节变化特征，结合气团后向轨迹模拟，估算南海大气氮沉降通量，探讨南海大气氮主要来源和人为活动对南海大气氮输入的贡献，以及来源的季节变化规律。通过分析大气沉降硝酸盐氮氧同位素组成和大气O3、OH浓度变化关系，揭示大气氮氧化物形成硝酸盐的氧化路径。分析大气降水雨量、雨强与其对应降水硝酸盐含量和氮氧同位素组成的关系，揭示冲刷过程中可能引起的氮同位素分馏机理。本研究成果将有望估算南海大气氮沉降输入的通量和人为活动对南海氮输入的影响，有助于更好的揭示南海大气氮源的季节变化规律，为南海区域氮循环的研究提供新证据，同时将助于升华大气氮氧化物氧化路径的理论意义，具有重要的现实意义和创新意义。

中文关键词： 硝酸盐；氮同位素；氧同位素；来源；南海

英文摘要： Most of studies about amtospheric nitrate deposition is concentrated in the inland aereas or offshore aeras. So, different atmospheric nitrate sources and atmospheric nitrogen depostiton flux in Yongxing Island of Xisha, South China Sea will be investigated in long term in this program, combined with the basic principles and research methods of isotope geochemistry and atmospheric chemistry, by anlysis the main ions and nitrogen, oxygen isotopic composition of atmospheric deposition. And then, it will reveal the contribution of atmospheric nitrogen of inland human activities input on the South China Sea, as well as the seasonal variation of sources. At the same time, it will reveal the oxidation path of NOx to NO3- combined with the O3 and OH concentration in the atmosphere. By ananlysis rainfall and its intensity, combined with nitrate concentration and nitrogen and oxygen isotopic composition in precipitation, we will explore the wash out efficiency and nitrogen isotope fractionation mechanisms. These results in this program, are expected to assess the fluxes of atmospheric nitrogen in the South China Sea and the impact of anthropogenic, will help to better reveal the seasonal variation of atmospheric nitrogen sources, which will provied new evidence of the nitrogen cycle. And the results will help to elevate

英文关键词： NO3-；nitrogen isotope；oxygen isotope；sources；South China Sea