广东海陵岛北部海域表层沉积物重金属分布特征与污染评价

Distribution characteristics and pollution assessment of heavy metals in the surface sediments in the northern Hailing island sea areas,Guangdong province

为了解海陵岛北部海域表层沉积物重金属污染状况,本研究于2017年11月在海陵岛北部海域采集11个站点的表层沉积物,系统地检测了沉积物中的粒径分布和典型重金属的含量(Hg、Cu、Pb、Zn和Cd),采用潜在生态危害指数法和地质累积系数法对沉积物中重金属污染程度进行评价,并且定性地分析了沉积物粒径对重金属分布的影响以及各种重金属的可能来源。研究结果表明,重金属(除Hg外)在空间上呈现出在近岸或者河口处含量高而到中心海域处含量低的趋势,并且沉积物粒径从西向东呈细-粗-细的变化趋势。将海陵岛北部海域沉积物重金属含量与《海洋沉积物质量》中的Ⅰ类标准对比,绝大多数的重金属含量均低于Ⅰ类标准。但是,通过计算得出沉积物重金属的潜在生态危害指数RI的变化范围为168.6~747.5,平均值为322.47,说明该海域沉积物中重金属对生态的潜在威胁较大。地质累积系数I_(geo)的平均值排序为:Hg(2.09)>Cu(0.70)>Zn(0.38)>Pb(-1.01)>Cd(-1.40)。重金属(除Hg外)几乎都低于轻度污染水平,相对污染较重的区域均集中在近海区域,这表明近岸人类活动是海洋沉积物重金属污染的潜在原因。重金属含量和沉积物粒径之间的相关性分析表明,重金属含量与沉积物粒径之间呈负相关性,即粒径越小越有利于重金属的富集。另外,重金属之间的相关性和聚类分析结果表明,该海域沉积物中的Cu、Cd和Pb可能受入海河流输入的影响而累积,而沉积物中的Zn和Pb可能来源于海陵岛及周边陆地的人类活动,Hg可能来源于海湾东南部某处的人为污染。

In order to investigate the pollution level of heavy metals in surface sediments in the northern part of Hailing island,the surface sediments were collected from 11 sites in November 2017.The concentrations of heavy metals(Hg,Cu,Pb,Zn,and Cd)in sediments and the sediment particle size were systematically tested.We evaluated the pollution level of sediment heavy metals using the potential ecological risk index and the geoaccumulation index.Qualitative assessment of the influence of sediment particle size on the distribution characteristics of heavy metals and tracking the possible sources of heavy metals were also conducted.The synthetical results showed that heavy metals except Hg had a higher concentration in the nearshore or estuarine areas than that in the central sea area.The particle size of sediment showed a fine-coarse-fine trend from west to east.Comparing with the national marine sediment quality,almost all heavy metal concentrations of surface sediment in different sampling sites did not exceed the ClassⅠstandard.The range of potential ecological risk index(RI)was 168.6~747.5,and the average of the RI was 322.47.It means that the heavy metals in the sediments of Hailing island sea area had a great potential to influence the environmental and ecology conditions.The rank of mean value of the geo-accumulation index(I_(geo))was:Hg(2.09)>Cu(0.70)>Zn(0.38)>Pb(-1.01)>Cd(-1.40),indicating that the heavy metals except Hg manifested in a level of light pollution.The relatively heavy pollution areas concentrated in the nearshore areas,indicating that human activities were responsible for the heavy metal pollution.The correlation analysis between heavy metals and sediment grain size showed that a negative correlation existed between heavy metals concentration and sediment particle size,indicating that the smaller the particle size,the stronger enrichment ability of heavy metals.In addition,the correlation and clustering analysis between heavy metals indicated that Cu,Cd and Pb may be accumulated due to the river input,while Zn and Pb could be derived from human activities in Hailing island,and Hg may come from human-made pollution sources in the southeastern part of the bay.