小溪港·望虞河对贡湖湾水质及微囊藻毒素-LR的影响

Effects of Xiaoxi Port and Wangyu River on Water Quality and Microcystin-LR in Gonghu Bay

[目的]考察贡湖湾入湖河道对贡湖湾水质及MC-LR的影响。[方法]对贡湖水体及其主要入湖河道小溪港、望虞河进行了为期1年的水质监测(2014年6月—2015年5月),分析了高锰酸盐指数(CODMn)、总氮(TN)、总磷(TP)、氨氮(NH+4-N)、溶解氧(DO)及微囊藻毒素-LR(MC-LR)的时空分布特征。利用美国EPA推荐的模型——健康风险评价"四步法"对MC-LR进行非致癌评价。并采用SPSS软件分析了MC-LR与典型环境因子之间的相关性。[结果]研究区域内TN、TP是主要特征污染物,小溪港和望虞河水质氮、磷含量高于贡湖湾内部,小溪港、望虞河和贡湖湾内部MC-LR平均浓度分别为0.47、0.46和0.38μg/L,入湖河流对贡湖湾水质污染有一定贡献。MC-LR的健康风险值HIcgw在0.11~0.38,远低于基准值。MC-LR与TP呈显著正相关(P<0.05)(R2=0.628);与TN呈正相关,但相关性不显著。TP可能是影响MC-LR生成的主要因素。[结论]贡湖湾水体的主要超标因子为氮和磷,并存在一定浓度MC-LR,有一定的健康风险。今后需控制营养盐浓度,从而控制MC-LR的健康风险。

[ Objective] To investigate the influence of inflow channel of Gonghu Bay on water quality and MC - LR. [ Method ] Water parameters such as CODMn, TN, TP, NH4^＋ -N, DO and MC -LR as well as their spatial and temporal distribution were analyzed in Gonghu Bay and its inflow rivers.（Xiaoxi Port and Wangyu River）, from June 2014 to May 2015. The carcinogenic evaluation from MC - LR was further estimated with US EPA health risk assessment （four-step method）. The correlation between MC - LR and typical environmental factors was evaluated with SPSS. [ Result] TN and TP were the major pollutants in the study area. The nitrogen and phosphorus contents in the Xiaoxi Port and Wangyu River were higher than those in Gonghu Bay. The average concentrations of MC - LR in the Gonghu Bay, Wangyu River and Xiaoxi Port were 0. 47, 0. 46 and 0. 38 μg/L respectively, indicating that inflow rivers contributed some pollutants to Gonghu Bay. The health risk value of MC - LR HIcgw was 0.11 - 0.38, which was much lower than the reference value. There was a significant positive correlation between MC - LR and TP （ P 〈 0.05 ） （ R^2 = 0. 628 ）, and a positive correlation between MC - LR and TN without significance. TP may be the main factor affecting MC - LR generation. [ Conclusion] Nitrogen and phosphorus were the major pollutant factors in Gonghu Bay. The existence of MC - LR in water exhibited certain health risk in Gonghu Bay. Nutrient concentration of the study area need to be controlled to lower the health risks of MC - LR in the future.