白茅海潮滩重金属空间分布特征及生态风险评价

本研究于2020年8月测定了白茅海潮滩表层、次表层（50 cm深）沉积物及间隙水、排放废水中9种重金属（Zn、Cr、Pb、As、Cu、Cd、Ni、Fe、Mn）的含量，利用潜在生态危害指数法以及相关性分析法，结合沉积物粒度特征和TOC含量对白茅海潮滩重金属的分布特征、相关关系和污染风险进行了分析。结果表明，调查区表层沉积物以砂为主，粘土和粉砂含量极少，TOC平均含量为0.031%，重金属含量为Fe>Mn>Zn>Cr>Pb>As>Ni>Cu>Cd。沿岸方向上，P1剖面某些重金属含量高于整个调查区平均含量，出现富集趋势。表层沉积物中的重金属在垂岸方向未表现出明显的分布规律。不同深度沉积物Pb、Zn、Cu、Cr、As、Cd含量均低于国家海洋沉积物I类标准值。间隙水中重金属含量为Mn>Fe>Zn>As>Ni>Cu>Pb>Cr>Cd，Cr、Fe、Mn在不同介质中含量差异较大。调查区氧化还原类金属对重金属含量影响较大，粒度和TOC对重金属含量影响较小。调查区综合潜在生态风险指数ERI为113.03，表现为轻微潜在生态危害。各重金属潜在生态污染程度为Cd>As>Pb>Cu>Zn>Cr。Cd为调查区表层沉积物中的主要污染因子，应列为白茅海潮滩优先控制的重金属。

Spatial distribution characteristics and ecological risk assessment of heavy metals in the tidal flat at the Baimaohai

In August 2020, the contents of 9 heavy metals (Zn, Cr, Pb, As, Cu, Cd, Ni, Fe, Mn) in the surface and subsurface (50 cm deep) sediments, interstitial water, and discharged wastewater of the Baimaohai tidal flat were determined, used the potential ecological risk index method and correlation analysis to analyzed the distribution characteristics, pollution risks and related relationships of heavy metals in the Baimaohai tidal flat based on the sediment grain size and TOC content. The results showed that the study area was mainly sand, with very little clay and chalk, of which the average TOC content was 0.031%, the content of heavy metals was Fe>Mn>Zn>Cr>Pb>As>Ni>Cu>Cd. Along the coast, there was an enrichment tendency for heavy metals in the P1 profile where the content of some heavy metals exceeded the average expectation. The distribution of heavy metals in surface sediments along the vertical direction was no obvious regularities. The content of Pb, Zn, Cu, Cr, As, Cd in the sediments at different depths were all below the permissible values of the class-I marine sediments(China Marine Sediment Quality Standards). The content of heavy metals in interstitial water was Mn>Fe>Zn>As>Ni>Cu>Pb>Cr>Cd, and for Cr, Fe, and Mn, their contents in the different mediums were significantly different. In the study area, the redox metals had a great influence on the content of heavy metals, while the grain size and TOC had a little influence. The value of comprehensive potential ecological risk index ERI was 113.03, which belonged to the category of minor ecological potential risk. The potential ecological pollution degree of each element was Cd>As>Pb>Cu>Zn>Cr. Cd was the main pollution factor in the surface sediment of the study, which should be listed as the priority element to be controlled in the tidal flat at the Baimaohai.