海南红树林湿地沉积物中重金属的累积

Accumulation of heavy metals in sediment of mangrove wetland from Hainan Island

于2008年在海南典型红树林湿地东寨港、三亚湾和亚龙湾采集沉积物样品,使用原子吸收分光光度法(SOLAAR M6)分析沉积物中Cu、Pb、Zn、Cd和Cr的含量,原子荧光光度法(AFS-8130)分析Hg和As的含量。表层沉积物中Cu、Pb、Zn、Cd、Cr、Hg和As的平均含量分别为14.8±9.2、24.1±9.2、57.9±36.5、0.17±0.10、29.6±20.4、0.08±0.04和9.7±4.4μg.g?1干重(DW),目标化合物(除Cd外)的含量均具有东寨港高、三亚湾次之而亚龙湾低的特点,Cd的含量各区域相近。与国内外其他典型红树林沉积物中重金属的含量相比,本研究区域沉积物重金属含量处于中偏低的水平,这与海南目前开发程度较低、人类活动影响较小相一致。柱状沉积物中Cu、Pb、Zn、Cd、Cr和Hg含量的剖面分布均具有表层稍低、中上层较高和底层相对低的特征,而As的含量呈现表层较高、中上层低和底层相对高的特点。潜在风险分析显示,本研究区域沉积物中重金属(As除外)目前污染较轻,对生态环境影响较小。

Sediment samples were collected in 2008 from the Dongzhai Harbor,Sanya Bay,and Yalong Bay,typical mangrove wetlands of Hainan Island.The concentrations of Cu,Pb,Zn,Cd,and Cr were analyzed using the Atomic Absorption Spec-trometer（SOLAAR M6）,and Hg and As,using the Atomic Fluorescence Spectrometer（AFS-8130）.The average concentra-tions of Cu,Pb,Zn,Cd,Cr,Hg,and As in surface sediments are 14.8±9.2,24.1±9.2,57.9±36.5,0.17±0.10,29.6±20.4,0.08±0.04,and 9.7±4.4 μg.g？1 dry weight,respectively.The levels of target chemicals except for Cd in sediments show the following order： Dongzhai Harbor Sanya Bay Yalong Bay,while the levels of Cd were generally similar among the study-ing areas.Compared with those from other typical mangrove wetlands of the world,heavy metal levels in sediments from these studying areas are in low-to median-levels,which is consistent with the factors that Hainan Island is still in low exploi-tation and its mangroves suffer little impact from human activities.The vertical profiles of Cu,Pb,Zn,Cd,Cr,and Hg con-centrations in core sediments show the highest values in the middle-upper layers and the lowest values in the bottom layers,with the in-between values in the surface layers;while the vertical profiles of As have the highest concentrations in the bot-tom-layer sediments and the lowest concentrations in the middle-to upper-layer sediments,and the concentrations of surface sediments are in between the two.Potential risk assessment shows that the pollution status of all target heavy metals except As is still low and therefore their ecological and environmental effects are also low.