庙岛群岛西部海域表层沉积物重金属分布特征与生态风险评价

Spatial Distribution and Ecological Risk Assessment of Heavy Metals in Surface Sediments of Western Miaodao Archipelago

关键词:  庙岛群岛  表层沉积物  重金属  生态风险

Key words:  Miaodao Archipelago  surface sediments  heavy metals  ecological risk

摘要:

为了解庙岛群岛西部海域表层沉积物重金属的污染现状，2021年11月采集该区域32个站位表层沉积物样品，运用正定矩阵因子分解(PMF)模型、单因子指数(EF)法、富集因子法、地累积指数(I_geo)法、潜在生态风险指数(RI)法等方法，综合分析评价重金属元素的含量、分布特征、富集性和潜在生态风险。结果表明，Cu、Cr、Cd、Zn、Pb、As和Hg的平均质量浓度分别为16.56、61.58、0.120、50.51、16.19、7.41和0.021 mg·kg^-1。Cr、As和Pb高值区主要分布在南长山岛西南部；Cu、Zn和Hg高值区在大黑山岛西南部大体呈东西向条带状展布；Cd高值区在大黑山岛以西大体呈北东-南西向展布,各元素空间分布不均。除HB90站位Cr和As浓度超过标准外，其他各站位重金属元素浓度均低于国家标准中海洋沉积物质量第一类标准。从富集程度来看，除HB90站位的Cr为中等富集水平外，其他各重金属元素均处在无-轻微富集水平。地累积指数法评价结果表明，研究区的Cd主要为清洁-轻污染状态；HB90站位的Cr为偏中度污染状态，As为轻度污染。潜在生态风险评价结果表明，研究区表层沉积物重金属总体为轻微-中等潜在生态风险，主要污染元素为Cd和Hg。总体来说，庙岛群岛西部海域表层沉积物重金属污染程度较低。

Abstract:

In order to understand the pollution status of heavy metals in surface sediments in the western waters of Miaodao Archipelago,32 surface sediment samples were collected in November 2021.Various assessment approaches,including Positive Matrix Factorization (PMF) model,single factor index,Enrichment Factors (EF),Index of geo-accumulation (I_geo),and Hakanson's potential ecological Risk Index (RI),were used to comprehensively analyze and evaluate the content,distribution characteristics,enrichment,and potential ecological risk of heavy metals.The results showed that the average mass concentrations of Cu,Cr,Cd,Zn,Pb,As and Hg were 16.56,61.58,0.120,50.51,16.19,7.41 and 0.021 mg·kg^-1,respectively.The high value areas of Cr,As and Pb were mainly distributed in the southwest of Nanchangshan Island.The high value areas of Cu,Zn and Hg in the southwest of Daheishan Island were generally distributed in an east-west banding pattern.The high value area of Cd element was generally distributed in the northeast-southwest direction in the west of Daheishan Island,and the spatial distribution of each element was uneven.Except for the HB90 station,where concentrations of Cr and As elements exceeded the standard values,the concentrations of heavy metal elements at other stations were lower than those of Class Ⅰ marine sediments in the national standard.From the perspective of enrichment degree,except for Cr at the HB90 station,the other heavy metal elements were at the level of no-slight enrichment.The evaluation results of the geo-accumulation index method showed that Cd in the study area was mainly clean-lightly polluted.Cr at the HB90 site was moderately polluted,and As was slightly polluted.The results of potential ecological risk assessment showed that the heavy metals in the surface sediments of the study area were generally mild to moderate potential ecological risks,and the main pollution elements were Cd and Hg.In general,the heavy metal pollution of surface sediments in the western waters of the Miaodao Archipelago is relatively low.