北海互花米草湿地土壤重金属分布及其污染评价

本研究通过分析广西北海互花米草(Spartina alterniflora)湿地土壤重金属(Cu、Zn、Cd、Pb、Cr)含量的分布特征及其与理化性质的相关性，并对重金属进行风险评估，为滨海湿地互花米草的生态利用和治理提供指导。于2020年6月选择广西北海丹兜海、营盘镇互花米草湿地及两者光滩作为研究地点，采集土样并测定土壤理化指标，采用地累积指数法和潜在生态风险指数法对5种重金属进行污染评价。结果表明：互花米草湿地表层土壤5种重金属含量的平均值均高于光滩，丹兜海湿地重金属含量高于营盘镇；地累积指数表明丹兜海互花米草湿地土壤的Pb为轻度污染；潜在生态风险评价显示5种重金属污染级别均为轻微；大部分重金属与沉积物中有机碳含量、粉粒和黏粒呈正相关，而与粗砂粒呈显著负相关。互花米草湿地可以累积重金属从而阻滞其进一步向海扩散，进而降低对海洋的生态风险。

Distribution and Pollution Assessment of Heavy Metals in Spartina alterniflora Wetland Soil in Beihai

The purpose of this study was to analyze the distribution characteristics of heavy metal (Cu,Zn,Cd,Pb,Cr) contents in soil of Spartina alterniflora wetland in Beihai,Guangxi and its correlation with physical and chemical properties.And the risk assessment of heavy metals was carried out to provide guidance for ecological utilization and management of S.alterniflora in coastal wetland.S.alterniflora wetland and mud flat in Dandou Sea and Yingpan Town of Beihai City,Guangxi Province were selected as the research sites in June 2020.Soil samples were collected and soil physical and chemical indicators were measured.The geo-accumulation index method and potential ecological risk index method were used to evaluate the pollution of 5 heavy metals.The results showed that the average contents of 5 heavy metals in the surface soil of S.alterniflora wetland were higher than those in mud flat,and the contents in Dandou Sea wetland were higher than those in Yingpan Town.Geo-accumulation index showed that Pb in S.alterniflora wetland soil in Dandou Sea was slightly polluted.Potential ecological risk assessment showed that the pollution levels of 5 heavy metals were slight.Most heavy metals were positively correlated with organic carbon content,silt and clay in sediments,but negatively correlated with coarse sand particles.S.alterniflora wetland can accumulate heavy metals to block their further diffusion to the sea,thereby reducing ecological risk to the ocean.