飞云江水系氮磷污染及硝酸盐氮来源解析

Analysis of nitrogen and phosphorus pollution and nitrate nitrogen source in Feiyun River water system

采集了飞云江水系干流和支流水样,分析了流域内不同区域水体的氮磷浓度,并通过Mix SIAR稳定同位素模型,解析了飞云江流域不同区域硝酸盐氮来源及其贡献。结果显示:(1)飞云江水系总氮为0.76~5.71 mg/L,从上游至下游浓度整体升高;总磷为0.01~4.83 mg/L,上中游低、下游高。(2)飞云江水系15 N自然丰度(δ^(15)N)和18 O自然丰度(δ^(18)O)分别为3‰~8‰、-7‰~0,土壤有机氮、污水和粪便是飞云江水系硝酸盐氮的主要来源,其中水体通过硝化作用进行氮转化过程,不存在反硝化作用。(3)飞云江水系中大气沉降、化肥和降水中氨氮、土壤有机氮、污水和粪便这4个污染源的贡献率分别为6.6%~25.4%、7.4%~29.2%、23.1%~56.1%、22.3%~40.8%。

Water samples were collected from the mainstem and tributaries of the Feiyunjiang River system,and the nitrogen and phosphorus concentrations in different regions of the watershed were analyzed,and the sources of nitrate and their contributions in different regions of the Feiyunjiang River basin were resolved by Mix SIAR stable isotope model.The results showed that:(1)total nitrogen in the Feiyun River system ranged from 0.76 mg/L to 5.71 mg/L,with an overall increase from upstream to downstream.Total phosphorus ranged from 0.01 mg/L to 4.83 mg/L,with low concentrations in the upstream and midstream and high concentrations in the downstream.(2)Theδ^(15)N andδ^(18)O in the Feiyunjiang River system were 3‰-8‰and-7‰-0,respectively.Soil organic nitrogen and urban domestic wastewater and manure were the main sources of nitrate nitrogen in the Feiyunjiang River system,in which the water body carried out the nitrogen conversion process through nitrification and denitrification does not exist.(3)The contribution of four pollution sources,namely atmospheric deposition,ammonia nitrogen from fertilizer and rainfall,soil organic nitrogen,sewage and manure,in the Feiyun River water system was 6.6%-25.4%,7.4%-29.2%,23.1%-56.1%,and 22.3%-40.8%,respectively.