海南东北部滨海湿地沉积物微量元素分布特征、来源及污染评价

Distribution Characteristics, Sources and Pollution Assessment of Trace Elements in Surficial Sediments of the Coastal Wetlands,Northeastern Hainan Island

对海南岛东北部滨海湿地128个站位表层沉积物中14种元素(Al_2O_3、Fe_2O_3、MnO、Cu、Ni、Sr、Zn、V、Pb、Cr、Zr、As、Cd和Hg)、总有机碳(TOC)含量和粒度进行测试分析.结果表明,研究区微量元素V、Cr、Ni、Cu、Zn、As、Pb、Cd和Hg平均含量分别为(40.13±32.65)、(35.92±26.90)、(13.03±11.46)、(11.56±10.27)、(48.75±27.00)、(5.48±1.60)、(18.70±8.66)、(0.054±0.045)和(0.050±0.050)μg·g^(-1),相比于珠江口、长江口、渤海湾沉积物和其他地质单元含量普遍偏低,而Sr和Zr的平均含量异常分别高达(1 253.60±1 649.58)μg·g^(-1)和(372.40±516.49)μg·g^(-1).研究区微量元素分布特征(除As、Sr和Zr)主要富集在海口湾、南渡江河口、演丰镇东寨港、清澜港文昌/文教河口、万宁小海等海湾和潟湖沉积环境中.通过研究区元素的相关性分析和因子分析(FA),结果显示海南岛东北部底质沉积物中Al_2O_3、Fe_2O_3、MnO、Cu、Ni、Zn、V、Pb、Cr和部分Hg主要来自于自然源;Cd和部分Hg来自于生物源,其分布受控于TOC;而As和部分Mn O显然受到了人类活动的干扰,其来源可能是沿岸水产养殖废水排放.依据沉积物质量基准Effect Range-Low(ERL)、Effect Range-Median(ERM)和Enrichment Factor(EF)值,计算表明研究区生态环境整体良好,沉积物微量元素污染程度较低,处于无污染-弱污染的程度.但是,22%的站位中Ni可能对海洋底栖生物产生负面影响.文昌市沿岸的冯家湾和龙马乡沿岸的人类活动已经造成区域局部微量元素整体的富集,应该引起重视.

Totally 128 surficial sediments samples were collected from the coastal wetlands,northeastern Hainan Island and analyzed for their concentrations of 14 elements including Al2O3,Fe2O3,Mn O,Cu,Ni,Sr,Zn,V,Pb,Cr,Zr,As,Cd and Hg,TOC and grain sizes. The mean concentrations of trace metals V,Cr,Ni,Cu,Zn,As,Pb,Cd and Hg were（ 40. 13 ± 32. 65）,（ 35. 92 ±26. 90）,（ 13. 03 ± 11. 46）,（ 11. 56 ± 10. 27）,（ 48. 75 ± 27. 00）,（ 5. 48 ± 1. 60）,（ 18. 70 ± 8. 66）,（ 0. 054 ± 0. 045）,（ 0. 050 ±0. 050） μg·g-（-1）,respectively,which were much lower than those in Pearl River Estuary,Yangzi River Estuary,Bohai Bay,upper crust and average shale. The average concentrations of Sr and Zr were much higher,reaching up to（ 1 253. 60 ± 1 649. 58） μg·g^-1 and（ 372. 40 ± 516. 49） μg·g^-1,respectively. The spatial distribution patterns of Al2O3,Fe2O3,MnO,Cu,Ni,Zn,V,Pb,Cr,Cd and Hg concentrations were the same as each other except for those of As,Sr and Zr. Generally,relatively high concentrations of these elements only appeared in the Haikou Bay,Nandu estuary,Dongzhai Harbor,Qinglan Harbor and Xiaohai in study area. The factor analysis revealed that the trace elements Al2O3,Fe2O3,MnO,Cu,Ni,Zn,V,Pb,Cr and part of Hg were mainly originated from the rock material by natural weathering processes,while the Cd and a part of Hg were from the biological source controlled by TOC. As and part of Mn O were influenced by anthropogenic source,especially by aquacultures. Zr and some MnO were derived from heavy minerals dominated by the coarse grain of sediments. In contrast to the ERL,ERM and the results of enrichment factors（ EF）,the environment of study area was good in general and the degree of contamination by trace elements was low on the whole. However,there are still some places where anthropogenic input have caused serious enrichments of trace elements and the occasional adverse effect on benthicorganism induced by Ni could probably occur in 22% areas of all the sampling stations.