珠江河口沉积物Hg的分布与污染评价

Distribution and contamination assessment of Hg in the sediments of the Pearl River Estuary

利用H异元素直测仪分析了珠江河口表层沉积物和柱状沉积物Hg的含量和背景值。沉积物Hg的背景值为（45．94～70．62）×10^-9。表层沉积物Hg含量在（20．81～369．20）×10^-9，平均为168．23×10^-9，平面分布呈西部向东部和东南方向减少的趋势，其中，以西部浅滩沉积物Hg含量最高，富集程度最大。柱状沉积物Hg含量在（33．61～250．43）×10^-9，平均含量150．49×10^-9，垂直分布存在显著的地域差异，东滩沉积物Hg表现为上部富集，而西滩沉积物表现为均匀分布。地质累积指数法、潜在生态危害指数法和单因子污染指数法三种污染评价的结果表明，珠江河口表层沉积物的Hg污染区主要集中于西部浅滩，存在中等程度的Hg污染。

The concentration and natural background of mercury in the surface and core sediments in the Pearl River Estuary were determined using Direct Mercury Analyzer. The mercury background level in the sediment is between 45.94× 10^-9 and 70.62 × 10^-9. In the surface sediments, the concentration of mercury ranged （20.81 ～ 369.20）× 10^-9 and the average concentration of mercury is 168.23 ×10^-9. Mercury in the surface sediments shows a decreasing trend from the west to east and southeast of estuary, and the maximum concentrations of mercury distribute in the West Shoal of the estuary with the highest enrichments. Mercury in the core sediments shows a concentration range of （33.61～ 250.43 ）×10^-9 and an average concentration of 150.49 × 10^-9. There is a regional difference in the vertical distribution of mercury in the cores. Mercury enriches in the upper part of the cores from the East Shoal, but the cores from the West Shoal appear uniform distribution of mercury along the depths. Mercury contamination in the surface sediments was assessed using three methods including Geo-accumulation Index, the potential Ecological Risk Index and Single Factor Contamination Index. The results showed that the contaminated areas of Hg mainly distributed in the West Shoal of the estuary with moderate Hg contamination.