南澳岛海域表层沉积物重金属分布、富集与污染评价

南澳岛是广东南澳县的主岛, 周边海域的环境保护被置于当地社会经济发展的重要位置。为此, 2004年 5月、7月选择以水产养殖为主的后江湾和白沙湾及以旅游为主的青澳湾作为研究对象, 对南澳岛海域重金属的 含量、分布、富集及污染状况进行了调查与评价。结果表明该海域重金属元素的平均含量为Cd: 0.19mg.kg-1, Cr: 26.86mg.kg-1, Cu: 20.71mg.kg-1, Ni: 22.78mg.kg-1, Pb: 35.67mg.kg-1, Zn: 79.48mg.kg-1, 低于近岸经济发达海域, 但高于受人类活动影响较小的外海; 在分布特征上表现为湾口高于湾内, 养殖区高于非养殖区的总趋势, 但在各海湾之间重金属含量并无显著差异, 表明南澳岛海域重金属主要来源于地表径流输入。该海域以城市污水中代表元素Cu (Cf = 2.75), Pb (Cf = 2.27)富集为主; 以海洋沉积物质量标准、沉积物质量基准和美国太平洋沿岸基线值评价, 南澳岛海域环境质量均处于健康状态, 但其潜在污染效应仍值得关注。

The distribution,enrichment and pollution assessment of heavy metals in surface sediments of sea areas around the Nanao Island

The Nanao Island is the main island of the Nanao County, Guangdong province, and the sea area around the island is important for local social and economic development. A survey of heavy metal content, distribution, enrichment and pollution state in sediments was conducted in May and July 2004. A total of eleven sediment samples were collected from mariculture base: Houjiang Bay, Baisha Bay and A tourist resort: Qingao Bay along the coast of the Nanao Island. The results showed that the contents of heavy metals were Cd: 0.19mg.kg-1, Cr: 26.86mg.kg-1, Cu: 20.71mg.kg-1, Ni: 22.78mg.kg-1, Pb: 35.67 mg.kg-1, Zn: 79.48mg.kg-1, much higher than those in similar bays of economically developed coastal areas and lower than those of offshore areas without anthropogenic impact. Average heavy metals in sediment tended to be lower in inner bays than at the mouth of the bay, and higher at aquaculture sites than non-aquaculture ones. However, there was no significant difference among studied bays, suggesting that river input maybe the main source of heavy metals in sea areas around the Nanao Island, which resulted in the enrichment of Cu (Cf = 2.75) and Pb (Cf = 2.27) that are representative elements of sewage. Based on the marine sediment quality standard, sediment quality criteria and baseline values for the United States Pacific Coast, the heavy metal pollution near the Nanao Island generally presented a slightly higher level. However, more attentions should be paid to the potential pollution effects.