亚硝酸盐稳定氮氧同位素示踪鄱阳湖边缘蚌湖硝化与反硝化过程

Due to the impact of human activity, Poyang Lake is significantly changed water level and resulted in a series of ecological and environmental problems. Previous studies considered that there were the processes of nitrification and denitrifcation in Poyang Lake. So Poyang Lake is an ideal place for studying nitrification and denitrification. Nitrite (NO2-) as a central intermediate species in the redox cycling of nitrogen, and produced and consumed by microbial processes such as both of nitrification and denitrification, is an ideal object studying nitrification and denitrification. In this program, the concentrations, δ15N and δ18O of NO2- in upper water and interstitial water, in Bang Lake, one of the edge lake of Poyang Lake, whose nitrogen sources are simple, will be analyzed to investigate the mechanisms of NO2- produced and consumed, the processes of nitrification and denitrification. At the same time, δ15N and δ18O of NO2-, δ15N and δ18O of NO3-, and δ15Nbulk, δ18O and SP of N2O, combined with environmental parameters and laboratory experiments will be used to identify the processes of nitrification and denitrification from different sides in Bang Lake, and discussed the effect of environmental parameters to these processes. The results in this program will help to better understand the mechanisms of N2O emissions in Poyang lake and provide a scientific basis for controlling the pollution in Poyang Lake. So, this program has important practical and innovative significance.

由于人为活动的影响，导致鄱阳湖的水位变化明显和生态环境趋向恶劣；并且前期研究认为，鄱阳湖存在强烈的硝化与反硝化作用。因此，鄱阳湖是理想地研究硝化与反硝化过程的重要场所。亚硝酸盐作为微生物硝化与反硝化过程都有的中间产物，是研究硝化与反硝化过程最理想的对象。本项目拟以鄱阳湖氮来源相对简单的一边缘湖蚌湖为研究区域，分析上层水体和间隙水等亚硝酸盐的浓度和氮氧同位素，揭示亚酸硝盐的生成与消耗机制以及硝化与反硝化过程；同时结合环境参数，硝酸盐氮氧同位素、N2O的氮氧同位素及SP值等，再采用室内模拟实验，利用多种研究手段从不同侧面探讨蚌湖硝化与反硝化过程，以及环境参数对这两过程的影响。本项目的研究结果，将有助于更好的理解鄱阳湖的N2O释放机制，为湖泊污染治理提供科学依据，具有重要的现实意义和理论意义。

由于人为活动的影响，导致鄱阳湖的水位变化明显和生态环境趋向恶劣；并且前期研究认为，鄱阳湖存在强烈的硝化与反硝化作用。本项目以鄱阳湖边缘湖蚌湖为研究对象，利用水化学、同位素地球化学手段，对鄱阳湖氮循环及其影响因素进行研究，并进行了多次野外采样和分析。研究结果表明，自然水体样品在采完样品后立即加入HgCl2进行保存，并于60d内测定NO2-浓度，以确保得到可靠的数据。枯水期鄱阳湖水体具有低NO3-浓度和低NH4+浓度的特征，表示其受到人类活动影响较小；NO3-/Cl-比值和Cl-浓度关系表明枯水期鄱阳湖水体硝酸盐主要受降水NO3-和土壤有机氮的影响；δ15N-NO3-和δ18O-NO3-的范围分别为-7.0‰ ~ 2.0‰(平均值-3.0‰)和4.5‰ ~ 68.3‰(平均值28.1‰)在降水NO3-、化肥及降水铵和土壤有机氮的δ15N和δ18O的端元值的区间内。δ15N和δ18O值表明枯水期鄱阳湖水体有比较明显的硝化反应发生。δ18O-NO3-值较高表示其所受大气氮沉降的影响较大；根据SIAR混合模型计算得出降水、化肥和土壤有机氮对鄱阳湖区域贡献较大，大气降水对鄱阳湖湿地硝酸盐来源的贡献不可忽视。本研究成果将有望将人为污染对淡水湖泊氮的贡献进行估算，有助于更好的揭示湖泊氮循环的规律，为湖泊氮循环的研究提供新证据，同时将助于升华淡水氮循环路径的理论意义，具有重要的现实意义和创新意义。在本项目的资助下，毕业3名硕士研究生；发表论文11篇，其中SCI论文6篇，EI论文1篇，中文核心论文4篇；申请专利1项。