白洋淀村落水域沉积物中营养元素和重金属分布特征及风险评价

Distribution characteristics of nutrient elements and heavy metals and its risk assessment in sediments around villages in Baiyangdian Lake

选取白洋淀下张庄、大田庄、邸庄、圏头乡、采蒲台5个典型淀中村为研究对象,分析村边水域沉积物中营养元素(N、P、S、OM)和重金属(Cd、Cr、Cu、Ni、Pb、Zn)的空间分布特征,运用有机污染指数法、污染指数法和潜在生态危害指数进行系统性的沉积物污染水平、生态风险评价.结果表明:沉积物TN、TP含量均值分别为1687.16和642.91 mg·kg^(-1),其TN、TP含量最高值出现在大田庄水道水域,TN含量均值排序均为水道>沟壕>塘>开阔水面;除采蒲台外其余村落有机指数均处于Ⅳ等级,沉积物中有机污染和有机氮污染较为严重.重金属Cd、Cr、Cu、Ni、Pb、Zn含量均值分别为0.17、55.77、35.52、28.25、19.99和119.74 mg·kg^(-1).Cd的富集系数均值为1.65,来源以人为输入为主.沉积物风险指数(SPI)相应等级为低风险级别(SPI=1.85<5),且潜在生态风险指数(RI)相应的亦为低生态风险(RI=76.87<150).村落水域沉积物的生物毒性排序为邸庄>下张庄>圏头>大田庄>采蒲台,邸庄水域沉积物生物毒性处于中-高水平,其余4个村落多为中-低等毒性.

Five typical villages in Baiyangdian Lake,Xiazhangzhuang(XZZ),Datianzhuang(DTZ),Dizhuang(DZ),Quantou(QT)and Caiputai(CPT),were selected to be studied.The spatial distribution characteristics of nutrient elements(N,P,S,OM)and heavy metals(Cd,Cr,Cu,Ni,Pb,Zn)in sediment around the villages were analyzed.Organic pollution index(OPI),sediment pollution index(SPI)and potential ecological risk index(RI)were employed to systematically evaluate the sediment pollution levels and ecological risks.The results showed that the average values of TN and TP were 1687.16 and 642.91 mg·kg^(-1),respectively.The max values of TN,TP and TC were located in the sediment of DTZ waterway,and the order of the average content of TN was waterway>ditch>pond>lake region near the residential area.Except CPT,the OPI of the villages were at level Ⅳ,which indicated that the organic pollution and organic nitrogen pollution in sediment were considerably serious.The average concentration of Cd,Cr,Cu,Ni,Pb,and Zn were 0.17,55.77,35.52,28.25,19.99 and 119.74 mg·kg^(-1),respectively.The enrichment factor of Cd was 1.65 averagely,indicating the anthropogenic input was the main source.Low risk level was identified by both the relative level of SPI(1.85<5)and RI(76.87<150).The order of biotoxicity of the sediments were DZ>XZZ>QT>DTZ>CPT.The biotoxicity of the sediments in some sites from the DZ were medium-high level,while biotoxicity were medium-low levels in other four villages.