淀山湖沉积物碳、氮、磷分布特征与评价

CHARACTERISTICS AND RISK EVALUATION OF CARBON,NITROGEN AND PHOSPHORUS IN SEDIMENTS OF THE DIANSHAN LAKE

淀山湖为黄浦江上游水源保护区,为了控制其富营养化趋势,在淀山湖影响区内实施了一系列外源污染控制措施。近年来,淀山湖水质持续改善,但每年仍有不同程度蓝藻水华暴发。为进一步探讨淀山湖水华暴发的机理,本研究对淀山湖沉积物进行了调查研究,分析了沉积物TOC、TN、TP时空分布特征。结果表明:在空间分布上,受来水与北部围网养殖影响及水体自净作用影响,淀山湖沉积物中营养物西北部高,东部低,进水口附近沉积物营养物浓度显著高于湖心及出水口。在垂直分布上,受航道回淤影响,D1与D4样点营养盐垂直分布规律不显著,其它样点均表现出随水深度增加营养盐显著降低的趋势。与20多a前相比,淀山湖沉积物营养盐存在明显的富集作用,沉积物氮、磷含量大幅上升。以有机指数与TP含量进行评价,淀山湖表层沉积物均属于重污染状态,且北部湖区污染程度较高。预测淀山湖外源污染得到控制以后,沉积物中营养物将对水体水质构成威胁。

Based on sampling work conducted in August of 2010,the temporal and spatial distribution characteristics of TOC,TN and TP in the sediments of the Dianshan Lake were analyzed.The results showed that the content of TOC ranged from 2.3 to 14.9 g/kg,TN ranged from 0.46 to 2.18 g/kg and TP ranged from 0.27 to 1.15 g/kg.In addition to the influence by the channel deposition,the concentration of pollutants in sediments decreased gradually with increasing depth.According to the organic indexes and TP contents,surface sediments of the Dianshan Lake belong to the state of heavy pollution and the pollution levels were higher in the northern part of the sampled site than the southern part.In order to efficiently control the internal source pollution,it is necessary to employ internal source pollution control measures such as ecological dredging.