Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA; Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA.
J Hazard Mater. 2021 May 15;410:124551. doi: 10.1016/j.jhazmat.2020.124551. Epub 2020 Nov 12.
Periphyton is ubiquitous in Florida Everglades and has a profound effect on mercury (Hg) cycling. Enhanced methylmercury (MeHg) production in periphyton has been well documented, but the re-distribution of MeHg from periphyton remains unknown. In this study, periphyton, sediments, surface water, periphyton overlying water, and periphyton porewater were collected from Everglades for analyzing the distribution of MeHg and total Hg (THg). Results showed that there were no significant differences in THg and MeHg in different types of periphyton, but they all displayed higher MeHg levels than sediments. MeHg distribution coefficients (logk) in periphyton were lower than in sediments, suggesting that periphyton MeHg could be more labile entering aquatic cycling and bioaccumulation. In water, the more the distance of water samples taken from periphyton, the lower the MeHg and dissolved organic carbon concentrations were detected. In extracellular polymeric substances of periphyton, MeHg in colloidal fractions was significantly higher than that in capsular fractions. It was estimated that approximately 10% (or 1.35 kg) of periphyton MeHg were passed on to mosquitofish entering the food web during wet season, contributing 73% of total Hg stocked in mosquitofish. These results revealed the importance of periphyton on water MeHg distribution and MeHg bioaccumulation in Everglades.
佛罗里达州大沼泽地普遍存在着周丛生物，其对汞（Hg）循环有着深远的影响。周丛生物中增强的甲基汞（MeHg）的产生已得到充分证实，但周丛生物中 MeHg 的再分布情况尚不清楚。在这项研究中，从大沼泽地采集了周丛生物、沉积物、地表水、覆盖周丛生物的水和周丛生物孔隙水，以分析 MeHg 和总汞（THg）的分布情况。结果表明，不同类型的周丛生物中 THg 和 MeHg 没有显著差异，但它们的 MeHg 水平都高于沉积物。周丛生物中的 MeHg 分配系数（logk）低于沉积物，表明周丛生物中的 MeHg 可能更容易进入水生循环和生物累积，从而变得更不稳定。在水中，距离周丛生物采集的水样越远，检测到的 MeHg 和溶解有机碳浓度就越低。在周丛生物的细胞外聚合物中，胶体部分的 MeHg 明显高于包膜部分。据估计，在雨季期间，大约有 10%（或 1.35 千克）的周丛生物 MeHg 通过进入食物网的食蚊鱼传递，这占食蚊鱼体内总 Hg 储量的 73%。这些结果揭示了周丛生物在大沼泽地水中 MeHg 分布和 MeHg 生物累积中的重要性。
