Bastos Wanderley R, Dórea José G, Bernardi José Vicente E, Lauthartte Leidiane C, Mussy Marilia H, Lacerda Luiz D, Malm Olaf
Laboratório de Biogeoquímica Ambiental, Universidade Federal de Rondônia, Brazil.
Faculdade de Ciências da Saúde, Universidade de Brasília, Brazil.
Environ Res. 2015 Jul;140:191-7. doi: 10.1016/j.envres.2015.03.029. Epub 2015 Apr 9.
The Madeira River is the largest tributary of the Amazon River Basin and one of the most impacted by artisanal gold-mining activities, deforestation for agricultural projects, and recent hydroelectric reservoirs. Total Hg (and methylmercury-MeHg) concentrations was determined in 3182 fish samples of 84 species from different trophic levels as a function of standard size. Species at the top of the trophic level (Piscivorous, Carnivorous) showed the highest mean total Hg concentrations (51-1242 µg/kg), Planctivorous and Omnivorous species showed intermediate total Hg concentrations (26-494 µg/kg), while Detritivorous and Herbivorous species showed the lowest range of mean total Hg concentrations (9-275 µg/kg). Significant correlations between fish size (standard length) and total Hg concentrations were seen for Planctivorous (r=0.474, p=0.0001), Piscivorous (r=0.459, p=0.0001), Detritivorous (r=0.227, p=0.0001), Carnivorous (r=0.212, p=0.0001), and Herbivorous (r=0.156, p=0.01), but not for the Omnivorous species (r=-0.064, p=0.0685). Moreover, fish trophic levels influenced the ratio of MeHg to total Hg (ranged from 70% to 92%). When adjusted for standard body length, significant increases in Hg concentrations in the last 10 years were species specific. Spatial differences, albeit significant for some species, were not consistent with time trends for environmental contamination from past alluvial gold mining activities. Fish-Hg bioaccumulation is species specific but fish feeding strategies are the predominant influence in the fish-Hg bioaccumulation pattern.
马德拉河是亚马孙河流域最大的支流，也是受手工采金活动、农业项目毁林以及近期水电水库影响最严重的地区之一。研究测定了来自不同营养级的84种鱼类的3182个样本中的总汞（以及甲基汞-MeHg）浓度，并将其作为标准体长的函数。处于营养级顶端的物种（食鱼性、肉食性）的平均总汞浓度最高（51-1242微克/千克），浮游生物食性和杂食性物种的总汞浓度处于中等水平（26-494微克/千克），而碎屑食性和草食性物种的平均总汞浓度范围最低（9-275微克/千克）。浮游生物食性鱼类（r=0.474，p=0.0001）、食鱼性鱼类（r=0.459，p=0.0001）、碎屑食性鱼类（r=0.227，p=0.0001）、肉食性鱼类（r=0.212，p=0.0001）和草食性鱼类（r=0.156，p=0.01）的鱼体大小（标准长度）与总汞浓度之间存在显著相关性，但杂食性物种不存在这种相关性（r=-0.064，p=0.0685）。此外，鱼类营养级影响甲基汞与总汞的比例（范围为70%至92%）。在根据标准体长进行调整后，过去10年中汞浓度的显著增加具有物种特异性。空间差异虽然对某些物种具有显著性，但与过去冲积层金矿开采活动造成的环境污染的时间趋势不一致。鱼类汞生物积累具有物种特异性，但鱼类的摄食策略是鱼类汞生物积累模式的主要影响因素。
