义乌岩口水库汇水区水质时空变化及富营养化特征研究

Spatiotemproal changes and eutrophic characteristics on water quality of Yankou Reservoir basin in Yiwu City

文章于2013~2018年对岩口水库流域逐月监测上游4条支流与水库的主要水质指标,分析水质因子的时空变化规律,并采用单因子评价法与综合营养状态指数评价法对岩口水库水质和富营养化状况进行综合评价。结果表明:上游4条支流的水质较差,而水库的水质情况稍好,多数月份水质优于地表水Ⅲ类标准,并且水库汇水区与中下游区域水质相似。单因子评价法显示,上游支流的总氮与总磷超标严重,超过90%的月份为富营养化状态,并且总氮也是岩口水库富营养化的主要贡献因素。综合指数法结果表明,上游支流大部分时间处于富营养化状态,而水库处于中营养状态。相比而言,氮是岩口水库富营养化的主要贡献因素,控制氮浓度能有效地治理水库富营养化。

The water quality of Yankou Reservoir was monitored monthly from 2013~2018 on the four main upstream tributaries and the reservoir itself.The spatiotemporal changes of the water quality factors were analyzed.And the water quality and the eutrophic conditions were also assessed through the single factor evaluation method and the comprehensive eutrophic index evaluation method.The results showed that the water qualities of the reservoir were better than those of the four tributaries,and the water quality of the upstream reservoir were close to those of middle and lower areas,which were collectively superior than the Class Ⅲ according to the Environmental Quality Standards for Surface Water.According to the single factor evaluation results,the TN and TP were greatly above the eutrophic limits in over 90% months,thus resulting in the upstream tributaries under eutrophic conditions,and TN was also the major contributing factor for eutrophication in Yankou Reservoir.Similarly,assessment through comprehensive eutrophic index evaluation method showed that the tributaries were collectively eutrophic,while the reservoir was mesotrophic for the most time during the monitoring period.In comparison,nitrogen was still the major controlling factor for reservoir eutrophication,and further measures were needed to mitigate nitrogen concentration in Yankou Reservoir.