湖北省保安湖沉积物污染评价及其影响因子分析

Evaluation of pollution statues and the influencing factors in sediment in Bao an Lake,Hubei Province

为了解保安湖沉积物的污染情况,采用单因子污染指数法、综合污染指数法和有机污染指数法分析了保安湖2020年7月—2021年4月共4个季度总氮(TN)、总磷(TP)和有机质(OM)的污染状况。结果表明:保安湖沉积物中TN、TP、OM含量分别为(3.56±0.79)、(0.57±0.20)、(59.66±16.27)g/kg;主体湖、桥墩湖、扁担塘和肖四海4个湖区TN、TP和OM含量均在冬季最高、夏季较低,季节更替引起的水温、浮游藻类、水生植物、微生物活性、溶氧及外源有机物输入等因素的变化,是导致这种季节差异的主要原因;TN和OM含量均在保安湖北部的扁担塘最高、南部主体湖最低,TP含量在北部的肖四海最高、扁担塘最低,来自周边精养鱼池的养殖废水及城镇生活污水可能是导致北部湖区沉积物营养含量更高的主要因素;沉积物中TN、TP和OM的单因子污染指数及综合污染指数均表明保安湖处于重度污染状态,有机污染指数显示其污染等级为有机污染。研究表明,保安湖沉积物污染状况较重,未来一段时间内若外源污染持续存在还可能存在继续恶化的风险,亟须采取控源截污、水生态修复等措施以控制其富营养化。

In order to understand the situation of sediment pollution in Bao an Lake,single-factor pollution index,comprehensive pollution index,and organic pollution index were used to analyze the pollution status of total nitrogen(TN),total phosphorus(TP)and organic matter(OM)based on the seasonal investigation of sediments in 12 sampling sites in Bao an Lake from July 2020 to April 2021.The results showed that there was content of(3.56±0.79)g/kg in TN,(0.57±0.20)g/kg in TP,and(59.66±16.27)g/kg in OM in the surface sediment of Bao an Lake,with the maximal levels of TN,TP,and OM in winter,and lower in summer in the four lake areas.Such seasonal differences in sediment nutrients were primarily involved in changes in water temperature,phytoplankton,aquatic plants,microbial activity,dissolved oxygen,and external organic matter input in different seasons,with the maximal levels of both TN and OM in Biandantang located in the north Bao an Lake and the minimal levels in the main Lake located in the south of Bao an Lake.The maximal level of TP was observed in Xiaosihai located in the north Bao an Lake,while the minimal in Biandantang.Aquaculture effluent from the surrounding intensive fish ponds and domestic sewage from the surrounding towns were the main factors resulting in the higher nutrients content of sediments in northern Bao an Lake.The single-factor pollution index and the comprehensive pollution index showed that Bao an Lake was heavily polluted,and the organic pollution index revealed an organic pollution problem.The findings indicated that the pollution status of Bao an Lake was heavy,and maybe heavier in the future if external pollution persists.Therefore,it is urgent to carry out a series of measurements such as nutrient reduction and ecological restoration to control the eutrophication of Bao an Lake.