滦河干流表层沉积物中营养元素和重金属含量分布特征及其风险评价

Distribution characteristics of nutrient elements and heavy metals content and its risk assessment in surface sediments from Luan River mainstream

选取滦河干流为研究对象,采集表层沉积物并分析其粒径分布、营养元素(N、P、C、S)及重金属(Cd、Ni、Cu、Zn、Cr和Pb)含量分布特征,对重金属采用富集系数法进行源解析,并利用地积累指数法、污染指数法和潜在生态危害指数法进行系统性的生态风险评价。结果表明:沉积物营养元素TN、TP、TC、TS均值为1 047.6、1 427.4、20 060.9和1 564.2 mg·kg^(-1),且分布存在空间差异性;粒径分布特征为粉砂或砂占比重大,黏土占比重小;重金属Cd、Cu、Ni、Zn、Cr和Pb含量均值分别为0.28、40.48、31.48、88.67、16.45和21.5 mg·kg-1,Cd、Cu、Ni、Zn超过河北省土壤背景值;Cd富集系数均值为2.31,其污染主要源是人为输入,其余重金属未见明显富集现象;相关性分析和主成分分析表明Cd与Cr、Cu、Ni、Zn呈显著正相关,Cr与Cu、Ni、Zn呈显著正相关,Pb与Fe、TP呈显著正相关,Cu与Ni、Zn呈显著正相关,Ni与Zn呈显著正相关;基于地累积指数法得Cd为重金属首要污染物;单项生态危害指数均值大小顺序为Cd(94.39)>Cu(9.28)>Ni(5.11)>Pb(2.16)>Zn(1.13)>Cr(0.48);沉积物风险指数(SPI)相应等级为低风险级别(SPI=2.75<5),且整体潜在生态风险指数(RI)相应的亦为低生态风险(RI=112.561<150)。

The surface sediments from Luan River mainstream was taken for the study of characteristics of particle size,nutrient elements （N,P,C,S）,and heavy metals （Cd,Ni,Cu,Zn,Cr and Pb）.The source of heavy metals was investigated by using enrichment factor （EF）,and index of geoaccumulation,sediment pollution index,and potential ecological risk index were deployed for the evaluation of systematic ecological risks.The results showed that particle distribution showed that silt and sand account for a significant proportion.The average concentrations of TN,TP,TC,and TS were 1 047.6,1 427.4,20 060.9 and 1 564.2 mg·kg^-1,respectively,and significant spatial difference of nutrient elements was observed.Mean contents of Cd,Cu,Ni,Zn,Cr,and Pb were 0.28,40.48,31.48,88.67,16.45 and 21.5 mg·kg^-1,respectively.The enrichment factor of Cd was 2.31 averagely,indicating the anthropogenic input was the main source.However,the source of other metals was natural since the enrichment factor was less than 1.5.The cumulative index revealed that Cd was of the main contributor of heavy metal pollution,which followed the order of Cd （94.39） Cu （9.28） Ni （5.11） Pb （2.16） Zn （1.13） Cr （0.48） calculated by single factor ecological risk index,and low risk level was i-dentified furtherly by both the relative level of sediment pollution index （SPI） and the overall potential ecological risk index （RI）.