浙北平原河网地区典型湖漾水生态健康评价研究--以德清县苎溪漾为例

Evaluation of Aquatic Ecological Health of Typical Lake in the River NetworkArea of Northern Zhejiang:A Case Study of Zhuxiyang Lake

基于不同生境特征的水生态系统尚缺乏差异性评价标准的现实需求,本文以浙北平原河网地区湖漾水生态系统为切入点,采用一套针对其功能结构及区域特征的湖漾水生态健康评价体系,选取一个典型湖漾分别从物理生境、水质、沉积物和水生生物等4大要素13项指标开展水生态健康评价研究。结果表明,德清县最大的湖漾苎溪漾水生态健康状况为亚健康。其中,物理生境健康方面,苎溪漾生态缓冲带宽度较大、植被覆盖率较高,生境状况较好,为保护生物多样性创造了良好条件;水质健康方面,苎溪漾溶解氧充足、富营养化程度适当,抗生素影响小,水质条件较好。但是,从沉积物健康来看,苎溪漾底泥中总氮、总磷浓度较高,存在内源污染风险;从水生生物健康来看,苎溪漾杂食性鱼类占比较高,导致浮游植物及浮游动物多样性指数均较低,不利于湖漾水生态系统的平衡和稳定。建议苎溪漾在渔业养殖中适当降低杂食性鱼类的养殖密度,避免对浮游生物的过度摄食;并采取相应的措施减少周边农业种植以及生活污染源的输入,控制底泥内源污染的累积风险。

Based on the lack of differential evaluation standards for aquatic ecosystems with different habitat characteristics,this paper took the lake aquaticecosystem in the river network area of north Zhejiang plain as the starting point,adopted a set of lake aquatic ecological health evaluation system according to itsfunctional structure and regional characteristics,and selected a typical lake to carry out aquatic ecological health evaluation research by evaluating 13 indicators offour essential factors including physical habitat,water quality,sediment and aquatic organisms.The results showed that the ecological health status of ZhuxiyangLake,which is the largest lake in Deqing County,was sub-healthy.The large width ecological buffer zone and high vegetation coverage rate of Zhuxiyang Lake,created a good habitat condition for the conservation of biodiversity.Sufficient dissolved oxygen concentration,appropriate eutrophication degree and low risk ofantibiotics,provided good water quality condition.However,high concentrations of total nitrogen and total phosphorus in the sediment of Zhuxiyang Lake,indicateda risk of endogenous pollution.A relatively high proportion of omnivorous fish,leading to a low diversity index of phytoplankton and zooplankton,revealed theimbalance and instability of Zhuxiyang Lake aquatic ecosystem.It is suggested that the breeding density of omnivorous fish should be appropriately reduced infishery aquaculture of Zhuxiyang Lake to avoid excessive feeding on plankton.And corresponding measures should be taken to reduce the input of agriculturalplanting pollution and domestic pollution sources surrounding Zhuxiyang Lake,in order to control the cumulative risk of endogenous pollution in sediment.