Department of Environmental Geochemistry, Fluminense Federal University, Outeiro São João Baptista, s/n., Centro, 24020-007 Niterói, RJ, Brazil.
Embrapa Forestry, Estrada da Ribeira km. 111, C.P. 319, 83411-000 Colombo, PR, Brazil.
Sci Total Environ. 2017 Jul 1;589:222-231. doi: 10.1016/j.scitotenv.2017.02.150. Epub 2017 Mar 1.
Mercury (Hg) is one of the most toxic nonessential trace metals in the environment, with high persistence and bioaccumulation potential, and hence of serious concern to environmental quality and public health. Emitted to the atmosphere, this element can travel long distances, far from emission sources. Hg speciation can lead to Hg contamination of different ecosystem components, as well as biomagnification in trophic food webs. To evaluate the effects of atmospheric Hg deposition in tropical forests, we investigated Hg concentrations in earthworm tissues and soils of two Forest Conservation Units in State of Rio de Janeiro, Brazil. Next, we performed a laboratory study of the biological responses (cast analysis and behavioral, acute, chronic and bioaccumulation ecotoxicological tests) of two earthworms species (Pontoscolex corethrurus and Eisenia andrei) to Hg contamination in tropical artificial soil (TAS) and two natural forest soils (NS) spiked with increasing concentration of HgCl. Field results showed Hg concentrations up to 13 times higher in earthworm tissues than in forest soils, while in the laboratory Hg accumulation after 91-days of exposure was 25 times greater in spiked-soils with 128mgHgkg (dry wt) than in control (unspiked) soils. In all the toxicity tests P. corethrurus showed a higher adaptability or resistance to mercury than E. andrei. The role of earthworms as environmental bioremediators was confirmed in this study, showing their ability to greatly bioaccumulate trace metals while reducing Hg availability in feces.
汞（Hg）是环境中最具毒性的非必需微量元素之一，具有高持久性和生物累积潜力，因此对环境质量和公共健康构成严重威胁。该元素排放到大气中后可以长距离迁移，远离排放源。Hg 的形态可以导致不同生态系统成分的 Hg 污染，以及营养食物链中的生物放大。为了评估大气 Hg 沉降对热带森林的影响，我们研究了巴西里约热内卢州两个森林保护区内蚯蚓组织和土壤中的 Hg 浓度。接下来，我们在实验室中研究了两种蚯蚓物种（Pontoscolex corethrurus 和 Eisenia andrei）对 Hg 污染的生物反应（蜕皮分析和行为、急性、慢性和生物累积生态毒理学测试），Hg 污染是用添加了不同浓度 HgCl 的热带人工土壤（TAS）和两种天然森林土壤（NS）来模拟的。野外结果表明，蚯蚓组织中的 Hg 浓度比森林土壤中的高 13 倍，而在实验室中，在 128mgHgkg（干重）HgCl 污染土壤中暴露 91 天后的 Hg 积累量比对照（未污染）土壤高 25 倍。在所有毒性测试中，P. corethrurus 对汞的适应性或抵抗力均高于 E. andrei。本研究证实了蚯蚓作为环境生物修复剂的作用，表明它们能够大量生物累积痕量金属，同时减少粪便中 Hg 的有效性。
