中国主要红树林湿地中甲基汞的分布特征及影响因素初探

通过对海南、广东、广西、福建的8个主要红树林地区沉积物中甲基汞以及环境因子的研究,分析了红树林生态系统中甲基汞的分布及其汞的甲基化作用.结果表明:①沉积物中总汞和甲基汞的含量分布并不一致.中国主要红树林区海南(三亚、东寨港)、广东(特呈岛、雷州、高桥、福田)、广西(大冠沙)、福建(浮宫)表层沉积物中甲基汞含量分别为(0.24±0.04)、(0.58±0.27)、(0.52±0.23)、(1.56±0.49)、(0.50±0.25)、(1.21±0.36)、(1.86±1.04)和(0.47±0.16)ng.g-1.甲基汞含量有很明显的地域区别,其含量顺序为大冠沙雷州福田东寨港特呈岛高桥浮宫三亚.工业和养殖业输入的汞和有机质显著增加了沉积物中甲基汞水平.对比世界其他河口湿地,我国红树林湿地沉积物中的甲基汞污染较为严重.②红树林沉积物的甲基化比率介于0.11%～7.13%.甲基化比率顺序由大到小为大冠沙特呈岛雷州福田高桥东寨港三亚浮宫.甲基化比率与砂粒显著正相关(p0.05),与粉粒和黏粒显著负相关(p0.05).③沉积物中总细菌含量范围为2.44×1010～1.91×1011CFU/g(以干重计,下同),浮宫三亚高桥东寨福田大冠沙.各环境因子对微生物数量的影响无显著差异.沉积物中SRB的含量介于1.73×104～4.92×106CFU/g,福田浮宫东寨港三亚高桥大冠沙.高有机废水是导致沉积物中SRB含量增高的主要原因.沉积物类型对SRB在沉积物表层的分布也有较大影响.甲基汞和环境因子之间并没有明显的相关性,外源输入是我国红树林湿地沉积物中的甲基汞污染的主要原因.

Distribution and Impact Factors of Methylmercury in Surficial Sediments from Main Mangrove Wetlands of China

Total mercury (THg), methylmercury (MeHg) and environmental factors were determined to study distributions of MeHg and Hg methylation in the sediments from 8 main mangrove areas of China. The results showed that it was not consistent for distributions of THg and MeHg in sediments. Concentrations of MeHg in sediments from Sanya, Dongzhaigang (Hainan Province), Techengdao, Leizhou, Gaoqiao, Futian (Guangdong Province), Daguansha (Guangxi Autonomous Region), Fugong (Fujian Province) were (0.24 +/- 0.04), (0.58 +/- 0.27), (0.52 +/- 0.23), (1.56 +/- 0.49), (0.50 +/- 0.25), (1.21 +/- 0.36), (1.86 +/- 1.04), (0.47 +/- 0.16) ng x g(-1) respectively. There were regional difference in MeHg contents which decreased in the order of Daguansha > Leizhou > Futian > Dongzhaigang > Techengdao > Gaoqiao > Fugong > Sanya. Input of Hg and organic matter from industry and aquiculture may lead to high level of MeHg. Compared with sediments from other estuaries of the world, serious pollution of MeHg was found in mangrove sediments of China. (2) % MeHg in mangrove sediments ranged from 0.11% to 7.13%, which decreased in the order of Daguansha > Techengdao > Leizhou > Futian > Gaoqiao > Dongzhaigang > Sanya > Fugong. There was significantly positive correlation between % MeHg and sandy fraction (p < 0.05), and significantly negative correlation between % MeHg and silt-clay fraction (p < 0.05). (3) Total bacteria (TB) in mangrove sediments ranged from 2.44 x 10(10) to 1.91 x 10(11) CFU/g (dry weight), TB decreased in the order of Fugong > Sanya > Gaoqiao > Dongzhaigang > Futian > Daguansha. Sulfate-reducing bacterium (SRB) ranged from 1.73 x 10(4) to 4.92 x 10(6) CFU/g, SRB decreased in the order of Futian > Fugong > Dongzhaigang > Sanya > Gaoqiao > Daguansha. Wastewater with high organic matters leads to high SRB. The types of surface sediments also had a great impact on the amount of SRB. There was no significant correlation among MeHg and environmental factors, which indicated that exogenous input is the main cause of MeHg pollution in mangrove sediments.