Controls of Methylmercury Bioaccumulation in Forest Floor Food Webs
Controls of Methylmercury Bioaccumulation in Forest Floor Food Webs
复制标题
森林地面食物网中甲基汞生物累积的控制
DOI：
10.1021/acs.est.8b06053
复制
发表时间：
2019
影响因子：
11.4
通讯作者：
Finlay, Jacques C.
中科院分区：
文献类型：
--
作者：
Tsz-Ki Tsui, Martin;Liu, Songnian;Brasso, Rebecka L.;Blum, Joel D.;Kwon, Sae Yun;Ulus, Yener;Nollet, Yabing H.;Balogh, Steven J.;Eggert, Sue L.;Finlay, Jacques C.
相对于对水生生态系统的广泛研究，对甲基汞在陆地生态系统中的来源和营养转移知之甚少。在这项研究中，我们研究能量流和营养结构，分别使用稳定的碳（δ 13 C）和氮（δ 15 N）同位素比值，和甲基汞水平的基础资源和陆地无脊椎动物从四个温带森林生态系统。我们发现，在所有地点，生物群中的甲基汞水平随着δ 13 C和δ 15 N的增加而显著增加（p< 0.01），这意味着微生物加工的饮食（δ 13 C增加）和生物体进食的营养水平（δ 15 N增加）对森林地面生物群中的甲基汞水平的重要性。甲基汞的营养放大斜率（定义为log 10 MeHg与δ 15 N的斜率）（0.20-0.28）无显著差异（p> 0.05）与不同的温带淡水系统相比（0.24 ± 0.07;n= 78），首次证明了甲基汞在这些对比鲜明的生态系统类型中向食物链上游移动的效率几乎相等。我们的研究结果表明，在现场生产的甲基汞在森林地面和有效的生物放大都提高甲基汞水平的食肉无脊椎动物在温带森林，这可以有助于显着的生物积累，这种神经毒素在陆地顶端捕食者。
Compared to the extensive research on aquatic ecosystems, very little is known about the sources and trophic transfer of methylmercury (MeHg) in terrestrial ecosystems. In this study, we examine energy flow and trophic structure using stable carbon (δ13C) and nitrogen (δ15N) isotope ratios, respectively, and MeHg levels in basal resources and terrestrial invertebrates from four temperate forest ecosystems. We show that MeHg levels in biota increased significantly (p< 0.01) with δ13C and δ15N at all sites, implying the importance of both microbially processed diets (with increased δ13C) and trophic level (with increased δ15N) at which organisms feed, on MeHg levels in forest floor biota. The trophic magnification slopes of MeHg (defined as the slope of log10MeHg vs δ15N) for these forest floor food webs (0.20–0.28) were not significantly different (p> 0.05) from those observed for diverse temperate freshwater systems (0.24 ± 0.07;n= 78), demonstrating for the first time the nearly equivalent efficiencies with which MeHg moves up the food chain in these contrasting ecosystem types. Our results suggest that in situ production of MeHg within the forest floor and efficient biomagnification both elevate MeHg levels in carnivorous invertebrates in temperate forests, which can contribute to significant bioaccumulation of this neurotoxin in terrestrial apex predators.