基于氮氧同位素示踪的农业面源氮源解析研究-以巢湖店埠河流域为例

Non-point souce pollution has been identified as the main factors which leads to the eutrificatiuon of the receiving waters, in which the percentage contribution and load of various pollution are one of the difficulty and focus. Nitrogen and oxygen isotopes, an effective tool to identify the sources and transformation mechanisms of nitrogen, can provide an effective origin traceability technology of non-point source nitrogen pollution. This research programe treat the Dianbu River catchmwent in the Chaohu Lake region as a research unit. Nitrogen and oxygen isotopes, modern information technology, traditional water sampling in combination with microbiology incubation would be applied to analyze the nitrogen concentrations and characteristics of nitrogen-15 and oxygen-18 istopic ratios in different sources (breeding wastewater, domestic sewage, farmland drainage, rainwater et al) and their transports and transformations in the source-ditch-river systerm. In the current research, the nitrogen concentrations and characteristics of nitrogen-15 and oxygen-18 istopic ratios of the Dianbu River would also be analyzed to interpret and clarify the different nitrogen sources and it's temporal and spatial variations. SIAR, a load computational model, would also be built to quantify the relative contributions of different nitrogen sources.This research could provide the scientific data for controlling the non-point source pollution and promote the study on the nitrogen biogeochemistry cycle.

面源污染是导致受纳水体水质恶化的重要污染源，各污染源的贡献率以及污染负荷的估算一直是面源污染研究的难点与重点之一。稳定同位素15N和18O联合示踪氮源及氮循环，为面源氮的溯源技术提供了新的思路和手段。本项目拟以巢湖店埠河流域为研究单元，通过氮氧同位素示踪技术、水化学分析、现代信息技术以及微环境培养等方法，分析不同污染源（养殖废水，生活污水，农田排水和雨水等）的各形态氮浓度和同位素（δ15N和δ18O）特征值，研究其在污染源-沟渠-河道迁移过程中与传输介质相互作用所表现出的“源”、“汇”特征，重点探讨氮氧同位素分馏系数在源-汇过程中的变化情况；分析店埠河河水中各形态氮浓度及同位素特征值的时空变化特征，识别店埠河面源氮的来源；构建SIAR混合模型，估算各污染源的贡献率。本申请项目的开展可以为控制农业面源污染提供科学依据，同时也可以丰富流域氮的生物地球化学循环理论。