Situation of sewage input reflected by nitrogen isotopic composition in a sediment core of Hongfeng Lake

摘要

Nitrogen in Hongfeng South Lake water mainly comes from sewage with high N concentrations from Pingba Chemical Fertilizer Plant (PCFP). Studies on the sediment core HF010427 sampled in the lake showed that the upward increase of nitrogen isotopic composition of sedimentary organic nitrogen (delta~(15)N_(org)) accorded with the trend of industrial total production (TP) of PCFC. On the contrary, diagenesis will theoretically cause an upward decrease of delta~15 N_(org). Because no treatment of sewage water was carried out, TP corresponds with sewage emission, indicating that sedimentary delta~(15)N_(org) can reflect well the total trend of sewage input. The very similar profile shape between nitrogen isotopic composition of sedimentary absorbed ammonium (delta~(15)NH_4~+_absorbed) and TP of PCFP suggests that delta~(15)NH_4~+_absorbed can be used to reconstruct more detailed situation of sewage input. The study has a reference to history investigation of sewage input.