基于水质综合指数法的亚热带水源型水库水质评价

为了解亚热带水源型水库——茜坑水库水质状况,基于2016年1月至2020年12月对水库pH值、高锰酸盐指数、五日生化需氧量、粪大肠菌群、氨氮、硝酸盐氮、总氮、总磷、硫酸盐、氯化物、氟化物、铁和锰等13个主要水质指标每月1次的监测数据,通过计算水质综合指数评价了水质状况,并通过多元线性回归优化水质综合指数模型。结果表明:水库水质整体较好,pH值和高锰酸盐指数受浮游植物繁殖影响,部分时段超标,总氮质量浓度偏高,总磷质量浓度和粪大肠菌群数部分时段较高,铁质量浓度的上升趋势应重点关注；表层监测难以全面体现分层对水质的影响,应增加垂向监测,全面掌握水库水质风险；利用由总磷、铁、高锰酸盐指数、氨氮和硝酸盐氮组成的主要污染指标水质综合指数模型可有效进行水质评价和管理。

Water quality evaluation of subtropical water source reservoir using water quality index method

To investigate the water quality status of the Xikeng Reservoir, a subtropical water source reservoir, monthly monitoring of the water quality in the reservoir was conducted from January 2016 to December 2020, so as to obtain the changing trends of 13 indictors, including pH value, permanganate index, biochemical oxygen demand for five days, fecal E. coli, ammonia nitrogen, nitrate nitrogen, total nitrogen, total phosphorus, sulfate, chloride, fluoride, iron, and manganese. The water quality index (WQI) was calculated to evaluate the water quality status, and the WQI model was optimized based on multiple linear regression. The results show that the reservoir water quality is generally good, the pH value and permanganate index exceed the standard in some periods due to the influence of phytoplankton reproduction, the mass concentration of total nitrogen is relatively high, the mass concentration of total phosphorus and number of fecal E. coli groups are high in some periods, and the uptrend of iron mass concentration should be paid much attention; it is difficult to fully reflect the impact of stratification on water quality only through surface monitoring, therefore, monitoring along the vertical direction should be used to fully obtain the water quality risk of the reservoir; the WQI model composed of main indictors, including total phosphorus, iron, permanganate index, ammonia nitrogen, and nitrate nitrogen, is an effective tool for water quality assessment and management.