破罡湖底泥重金属分布特征及潜在生态危害

Spatial Distribution of Heavy Metals and Their Potential Ecological Risk in Sediments of Pogang Lake

2009年7月,采用Mapinfo专题地图制作技术和Lars Hankson指数模型对破罡湖底泥中铜、铬、锌、镉和铅5种重金属污染的空间分布现状及潜在生态危害进行了研究。结果表明,①破罡湖底泥中铬、铜、锌、镉和铅的含量分别为110～145 mg/kg、51.9～68.1 mg/kg、119～155 mg/kg、1.05～1.41 mg/kg和38.0～62.1 mg/kg;其中,铜和镉的平均含量超过了《土壤环境质量标准》(GB15618-1995)二级标准限值,其他重金属平均含量则在允许范围内。②破罡湖底泥中铜与铬最大含量分布区域都出现在该湖东北部邻枞阳县处;底泥中锌和镉的分布也有一定相似性,最大锌含量和镉含量都出现在湖东北部的小合村以北处,而在湖东南部通江渠附近的锌含量和镉含量都是最小的;铜与铬和锌与镉具有协同毒性,其分布的空间重叠增加了其高含量区域的生态风险。③底泥中铅的高含量区域则出现在湖西湖滨带,汽车尾气排铅是破罡湖底泥中铅的重要来源。④破罡湖底泥中镉含量达到极强生态危害影响水平,其他4种重金属潜在生态危害轻微,由于镉的贡献,导致破罡湖底泥多种重金属潜在生态危害总体上达到很强的水平。

Over the last several decades,the lake environments have received large amounts of pollutants. Among these pollutants,most of the heavy metals（e.g.cadmium,lead,copper,chromium and zinc）may be toxic.Heavy metals are readily mobilized by human activities.Human activities have accelerated cycling and increased metal delivery of weathering products and pollutants to lake environments via the surfaces/waters which can be transported,deposited and buried along with sedimentary dynamics.In July 2009,the current situations of spatial distribution of concentrations of heavy metals including copper,chromium,zinc,cadmium and lead in sediments of Pogang Lake,and the potential ecological risk from the five kinds of heavy metals, were studied by means of Mapinfo thematic map production technology and Lars Hankson index model respectively. The result showed that concentrations of the heavy metals ranged 110-145 mg/kg,51.9-68.1 mg/kg, 119-155 mg/kg,1.05-1.41 mg/kg,and 38.0-62.1 mg/kg dry weight for chromium,copper,zinc,cadmium and lead,respectively.The copper concentration exceeded the threshold of second level standard of the GB15618-1995,the cadmium concentration also exceeded the threshold of second level standard,and the concentrations of other heavy metals were within permissible limits.The spatial distributions of the maximum concentrations of copper and chromium,cadmium and zinc were similar.The highest concentrations of these four kinds of heavy metals occurred at the northeast part of Pogang Lake which is adjacent to Zongyang city,of The copper and chromium,cadmium and zinc showed a synergistic or additional toxicity effect and the harmfulness of these metals would be amplified.The nail factories in Zongyang city possibly export the pollutant water which contains copper and chromium in electroplating process.At the northeast part of Pogang Lake, there are about 3.5 km^2 of paddy fields,the gross weight of cadmium which through the using of the phosphatic fertilizer exporting to this region.The maximum of lead concentration occurred at the western riparian, where the province highway named S228 was wriggling along the lakeside from north to south,so the automobile exhaust was assumed to be the important pollutant source of lead.Ingestion of even trace quantities of cadmium can influence not only the physiology and health of individual organisms but also the demographics, distribution,reproduction,and survival.The Hankson index of cadmium which signified potential ecological risk reaches up to 654.00.Besides,Hankson index also showed that the harmful of the other four heavy metals were slight.So cadmium was the main pollutant in the sediments of Pogang Lake.The cadmium pollution in the sediments led to the highest damages to the ecological system of Pogang Lake.