Department of Earth & Environmental Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH 45435, USA.
Environ Pollut. 2012 Jan;160(1):82-7. doi: 10.1016/j.envpol.2011.09.013. Epub 2011 Oct 14.
Litterfall is a major source of mercury (Hg) and toxic methylmercury (MeHg) to forest soils and influences exposures of wildlife in terrestrial and aquatic ecosystems. However, the origin of MeHg associated with tree foliage is largely unknown. We tested the hypothesis that leaf MeHg is influenced by root uptake and thereby related to MeHg levels in soils. Concentrations of MeHg and total Hg in deciduous and coniferous foliage were unrelated to those in soil at 30 urban and rural forested locations in southwest Ohio. In contrast, tree genera and trunk diameter were significant variables influencing Hg in leaves. The fraction of total Hg as MeHg averaged 0.4% and did not differ among tree genera. Given that uptake of atmospheric Hg(0) appears to be the dominant source of total Hg in foliage, we infer that MeHg is formed by in vivo transformation of Hg in proportion to the amount accumulated.
凋落物是汞（Hg）和有毒甲基汞（MeHg）进入森林土壤的主要来源，会影响陆地和水生生态系统中野生动物的暴露水平。然而，与树木叶片有关的 MeHg 的来源在很大程度上尚不清楚。我们检验了以下假设，即叶片 MeHg 受根系吸收的影响，因此与土壤中的 MeHg 水平有关。在俄亥俄州西南部的 30 个城市和农村森林地区，落叶树和针叶树叶片中的 MeHg 和总 Hg 浓度与土壤中的浓度无关。相比之下，树木属和树干直径是影响叶片中 Hg 的重要变量。总 Hg 中 MeHg 的比例平均为 0.4%，不同树种之间没有差异。鉴于大气 Hg(0)的吸收似乎是叶片中总 Hg 的主要来源，我们推断 MeHg 是通过 Hg 在体内的转化形成的，其比例与积累量成正比。
