南宁市大王滩水库水质评价及富营养化分析

Water Quality Evaluation and Eutrophication Analysis of Dawangtan Reservoir in Nanning

为进一步了解近几年大王滩水库整治成效,文章采用模糊标识指数法对2008~2016年水库的水质进行评价;选取CODMn、NH4^+-N、TP、TN、DO等指标分析年际浓度变化趋势;采用综合营养状态指数法评价大王滩水库富营养化状态。结果表明:大王滩水库水质总体改善,由2008年劣V类转变为2016年Ⅲ类,但饮用水源一级保护区水质不能达到饮用水水质目标要求,以致存在饮水安全风险;TN浓度得到有效控制,CODMn、DO浓度得到改善,TP和NH+4-N浓度控制不够理想,部分点位浓度有所增加;水库整体为中营养水平,然而综合营养指数接近中营养水平上限,且2016年较2015年略有反弹,需进一步加强环境整治。

Dawangtan reservoir is an important drinking water source in Nanning.The water quality affects the health safety of the local people seriously.To further understand remediation results of Dawangtan reservoir in recent years, this paper employed the fuzzy identification index method (FIIM) to evaluate water quality from 2008 to 2016.Permanganate index (COD Mn ), ammonia nitrogen (NH4^+-N), total phosphorus (TP), total nitrogen (TN) and dissolved oxygen (DO) were selected to analyze the trends of the annual concentration.The eutrophication status of Dawangtan reservoir was evaluated by comprehensive nutrition state index method.Results show that the overall water quality of Dawangtan reservoir was improved from poor V-grade (2008) to Ⅲ-grade (2016).However, the water quality of the first-grade protection zone of drinking water failed to meet the standard, thus resulting in the risk of drinking water safety.The concentration of TN was effectively controlled.The COD Mn and DO concentration were improved.Concentrations of TP and NH4^+-N were not well controlled since they are increased in some monitoring sites.The whole reservoir belonged to mesotrophic state.The comprehensive nutrition index approached the upper limit of the nutrition level, and the index value in 2016 increased slightly than that in 2015.Therefore, the environment needs to be further remedied.