基于稳定同位素示踪的流域颗粒有机物质来源辨析

为有效控制流域水质污染,保证饮用水水源的水质安全,通过采集和测定流域内土壤、植物以及河流断面水体悬浮颗粒有机质(POM)在枯水期和丰水期的碳、氮稳定同位素值和C/N比值,对石头口门水库汇水流域水体POM的来源进行研究.结果表明,水体中POM主要来源于土壤有机质,其贡献为69.2%,藻类等大型水生生物和浮游植物的贡献分别为23.1%和7.7%.流域水体中POM的来源存在时空差异.丰水期,浮游植物和藻类等大型水生植物的贡献均为15.4%,而枯水期后者的贡献提高到了30.8%.水体POM主要来源于双阳河和饮马河下游的土壤有机质,说明该区域土壤侵蚀较重,易发生非点源污染;岔路河和饮马河上游支流小黄河,水体POM以浮游植物的贡献占主导,其贡献分别为86.3%和94.8%,这些区域侵蚀较弱,非点源污染发生的风险小;大中型水库区域的POM主要由藻类等大型水生植物贡献,表明悬浮颗粒物在进入水库后可能发生了明显沉积.

Identifying sources of particles organic matter in surface water based on stable isotope tracing on basin scale

In order to assure the safety of surface drinking water, the sources of suspended particulate organic matter (POM) were studied in this paper by stable carbon and nitrogen isotopes analysis and elemental C/N ratios measure of POM. Soil and plant samples were collected in Shitoukoumen Reservoir Basin. The results showed that POM mainly sourced from soil organic matter which possessed 69.2%. Macrophyte was the second important contributor (23.1%). In addition, phytoplankton was also one of the sources of POM, accounting for 7.7%. The sources of POM existed seasonal and spatial variations. Over rainy season, the contributions of phytoplankton and Macrophytes to POM reached to 15.4%, respectively. While the contribution of Macrophyte to POM increased to 30.8% over dry season. Spatially, POM in surface water in the whole basin was from the soil organic matter in the lower reaches of Shuangyang river and Yinma river, owing to high soil erosion and the risk of non-point source (NPS) pollution in the regions. The phytoplankton, the main contributor of POM, possessed 86.3% and 94.8% in Chaluhe river and Xiaohuanghe river, respectively. And the soil organic matter contributed 13.7% and 5.2% in the two areas, respectively, where the low risk of NPS pollution showed low soil erosion. The most of POM from Macrophyte in reservoir indicated suspended particulates from the other sources may sink.