珠海市中部主要供水水库沉积物重金属时空分布与风险评价

Spatiotemporal Distribution and Pollution Risk Assessment of Heavy Metals in Sediments of Main Water Supply Reservoirs in Central Zhuhai City

磨刀门和洪湾水道是珠江水系的主要出海口,受潮汐影响,沿线受其调水的凤凰山水库、大镜山水库和竹仙洞水库是粤港澳大湾区珠海市中部的重要饮用水水源地.为了解3座供水水库表层沉积物中的环境质量状况,于2019年丰、枯两季(8月和10月)对库区共15个采样点的8项重金属进行监测,并开展了相关性分析、地累积指数评价、生态风险评估和溯源分析.结果表明,8种重金属在3座水库中的含量平均值大小排序均为:竹仙洞水库>大镜山水库>凤凰山水库.凤凰山水库Hg、Zn和Pb,大镜山水库Hg、As、Mn、Ni、Cu、Zn和Pb,竹仙洞水库8种重金属含量分别超过广东省土壤重金属背景值的1.88~2.75、1.05~2.32和1.69~6.45倍.除凤凰山水库的As,大镜山水库的As和Cu,竹仙洞水库的Cr和Ni外,其余重金属含量均呈现枯水期>丰水期的特征.地累积指数法评价结果表明,3座水库污染程度为:竹仙洞水库>大镜山水库>凤凰山水库.其中,凤凰山水库和大镜山水库仅Hg、Zn和Pb元素表现为轻度污染,竹仙洞水库整体均受到轻度或偏中度污染.潜在生态风险指数评价结果表明,凤凰山水库和大镜山水库整体均为低生态风险,竹仙洞水库为中生态风险,Hg是3座水库主要的生态风险贡献因子,贡献率分别为78.8%、64.4%和51.0%.

The Modaomen and Hongwan waterways are the main estuaries of the Pearl River system.Affected by tides,the Fenghuangshan Reservoir,Dajingshan Reservoir,and Zhuxiandong Reservoir,which are subject to water transfer along the river line,are important drinking water sources in the central part of Zhuhai City in the Guangdong-Hong Kong-Macao Greater Bay Area.Eight heavy metals in 15 sampling points in the reservoir area were monitored in the two seasons(August and October)of 2019.The environmental quality of the surface sediments of the three water supply reservoirs was surveyed using correlation analysis,geoaccumulation index evaluation,ecological risk assessment,and traceability analysis in the present study.The results showed that the order of the average content of the eight heavy metals in the three reservoirs was as follows:Zhuxiandong Reservoir>Dajingshan Reservoir>Fenghuangshan Reservoir.The contents of Hg,Zn,and Pb in Fenghuangshan Reservoir;Hg,As,Mn,Ni,Cu,Zn,and Pb in Dajingshan Reservoir;and Zhuxiandong Reservoir exceeded the background values of soil heavy metals in Guangdong province by 1.88-2.75,1.05-2.32,and 1.69-6.45 times.Except for As in Fenghuangshan Reservoir,As and Cu in Dajingshan Reservoir and Cr and Ni in Zhuxiandong Reservoir,the other heavy metals elements showed the content characteristics of dry season>wet season.The evaluation results of the geoaccumulation index method indicated that the pollution degree of the three reservoirs was in the order of:Zhuxiandong Reservoir>Dajingshan Reservoir>Fenghuangshan Reservoir.Among them,the Fenghuangshan Reservoir and the Dajingshan Reservoir were only slightly polluted by Hg,Zn,and Pb elements,and the Zhuxiandong Reservoir as a whole was slightly or moderately polluted.The evaluation results of the potential ecological risk index showed that the overall ecological risk of Fenghuangshan Reservoir and Dajingshan Reservoir was low,and Zhuxiandong Reservoir was at a medium ecological risk level.Hg was the main ecological risk-contributing factor of the three reservoirs,with contribution rates of 78.8%,64.4%,and 51.0%,respectively.