伊逊河春汛期水质波动原因解析

为探究伊逊河春汛期水质波动的主要原因，分别于2020年12月和2021年3月对伊逊河流域进行采样调查，在水环境因子时空特征分析的基础上，使用三维荧光光谱结合平行因子分析、荧光特征分析和Spearman秩相关分析，解析水体污染物的荧光特性和来源特征。结果表明：伊逊河春汛期水质明显恶化，Ⅴ类及劣Ⅴ类水体占比由14.29%升至88.24%，主要超标因子为COD_Cr、TP和COD_Mn；水体溶解性有机物（DOM）识别出3种荧光组分〔UVC类腐殖质（C1）、UVA类腐殖质（C2）和类色氨酸（C3）〕，类腐殖质总贡献率接近80%；冰封期和春汛期各采样点位水体溶解性有机物的荧光指数（FI）分别为1.65~1.88和1.49~1.75，自生源指数（BIX）分别为0.76~1.31和0.65~0.99，腐殖化指数（HIX）分别为0.10~7.00和0.40~6.00；春汛期伊逊河水体DOM表现出更强的腐殖性和较弱的近期自生源特性，陆源贡献比例显著提高；荧光参数FI、BIX与DOC、TP、COD_Cr和COD_Mn等水质参数呈显著负相关（R>0.6，P<0.01），春汛期水体DOC、TP等污染物浓度升高主要受高腐殖质背景、水土流失及农业面源污染的影响。

Cause analysis of water quality fluctuation of Yixun River in spring flood season

In order to explore the main reasons for water quality fluctuation in the Yixun River in the spring flood season, Yixun River Basin was sampled and investigated in December 2020 and March 2021, respectively. Based on an analysis of the spatial and temporal characteristics of water environment factors, the excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC), fluorescence characteristic analysis and Spearman rank correlation analysis were used in fluorescence characteristics studies and source characteristics studies. The results showed that the water quality of the Yixun River in the spring flood season deteriorated significantly, which was mainly reflected in the increase in the proportion of Class V and worse water bodies of the national standard from 14.29% to 88.24%. The main over-standard factors were CODCr, TP and CODMn. Three fluorescence components, including UVC humic-like substances (C1), UVA humic-like substances (C2), and tryptophan-like substances (C3) were detected in the dissolved organic matter (DOM) in the water body, of which the total contribution of humic-like substances accounted for nearly 80%. The fluorescence index (FI) of DOM during the freezing and spring flood seasons were 1.65-1.88 and 1.49-1.75, the biological source index (BIX) was 0.76-1.31 and 0.65-0.99, and the humification index (HIX) was 0.10-7.00 and 0.40-6.00, respectively. During the spring flood season, the DOM of the Yixun River body showed stronger humility and weaker recent autochthonous characteristics, and the proportion of land source contribution significantly increased. The fluorescence parameters of FI and BIX were significantly negatively correlated (R>0.6, P<0.01) with the water quality parameters such as DOC, TP, CODCr and CODMn. The increase of the concentration of DOC, TP and other pollutants in water bodies during the spring flood season was mainly affected by three factors, including high humus background, soil erosion and agricultural non-point source pollution.