慈溪市上林湖水质评价及沉积物污染特征

Water Quality Assessment and Pollutants Characteristics in Sediments of Shanglin Lake in Cixi County

对慈溪市饮用水源地上林湖水质和底泥污染调查研究表明,上林湖饮用水水源地的水质已从2级安全水平降到了3级基本安全水平.上林湖沉积物中总磷的含量约302mg/kg,其中有机磷占31.6%,无机磷占68.4%;沉积物中活性磷含量较高,主要以Fe-P为主,在外力扰动条件下易于向水体释放影响水质.湖区周边杨梅林地施肥土壤中速效磷含量极高,径流污染负荷最大.上林湖沉积物中Cd和Hg两种重金属污染较重,达到中度和较重生态风险等级;上林湖沉积物的PAHs生态风险较低.

Based on the survey of status of drinking water source in Cixi County,assessment of water quality of Shanglin Lake is carried out.The water quality level falls to grade 3（safety basically） from grade 2（safety）.Total P concentration in sediment is 302mg/kg,in which organic P accounts for 31.6% of the total P,and inorganic P accounts for 68.4%.Sediment contains much active phosphorus,P bound as Fe（Fe-P） was the dominant bioavailable phosphorus.The release characteristics of phosphorus were influenced markedly by the disturbing conditions.The content of soil available phosphorus（SAP） in waxberry surrounding Shanglin Lake was extremely high,so is the pollution loading in the runoff.The pollution of Cd and Hg is the most serious in sediment of Shanglin Lake,and the ecological risk level has reached medium to high level respectively.There is no serious ecological risk of PAHs in sediment of Shanglin Lake.