Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS) , Building 3, Courtyard 16, Lin Cui Road, Chaoyang District, Beijing 100101, People's Republic of China.
Environ Sci Technol. 2014 May 6;48(9):5220-8. doi: 10.1021/es404275v. Epub 2014 Apr 17.
Our understanding of the biogeochemistry of mercury (Hg) in high-altitude aquatic environments remains limited. The Tibetan Plateau (TP) is one of the Earth's most significant continental-scale high lands, yet much remains unknown about the Hg bioaccumulation and biomagnification in these pristine ecosystems. In this study, 166 wild fish samples of 13 species were collected from 13 rivers and lakes across the southern TP. Total Hg (THg) and methyl-Hg (MeHg) concentrations in the axial muscle of fish ranged from 25.1 to 1218 ng g(-1) of wet weight (median ± average deviation of 100.5 ± 149.2 ng g(-1)) and from 24.9 to 1196 ng g(-1) of wet weight (median ± average deviation of 90.7 ± 137.0 ng g(-1)), respectively. Hg concentrations varied greatly within and between species. The fish Hg concentrations were then linked to the limited available environmental Hg data and special geochemical characteristics in the region, such as Hg loading, pH, low temperature, and high ultraviolet (UV). The long lifespan and slow growth of the fish under the low-productivity environments may be the major biological factors that help to build up the fish Hg levels comparable to those observed in wild fish growing in human-impacted areas. δ(13)C signals suggested that pelagic fish had higher Hg concentrations, but no relationship was found between the Hg concentrations and the trophic levels. Zooplankton and benthic amphipods had typically higher percentages of MeHg compared to the previously reported values, suggesting the efficient transfer of MeHg from the base of the aquatic food web. This study sheds some light on the geochemical and biological controls of Hg bioaccumulation in fish and biomagnification in the aquatic food web in arid high-altitude environments.
我们对高海拔水生环境中汞（Hg）的生物地球化学了解有限。青藏高原（TP）是地球上最重要的大陆尺度高地之一，但这些原始生态系统中 Hg 的生物积累和生物放大作用仍有许多未知之处。本研究从青藏高原南部的 13 条河流和湖泊中采集了 13 个物种的 166 个野生鱼类样本。鱼体轴肌肉中的总汞（THg）和甲基汞（MeHg）浓度范围分别为 25.1-1218ng/g（湿重）（中位数±平均偏差为 100.5±149.2ng/g）和 24.9-1196ng/g（湿重）（中位数±平均偏差为 90.7±137.0ng/g）。Hg 浓度在种内和种间差异很大。然后将鱼类 Hg 浓度与该地区有限的环境 Hg 数据和特殊地球化学特征（如 Hg 负荷、pH 值、低温和高紫外线（UV））联系起来。在低生产力环境下，鱼类的长寿命和生长缓慢可能是导致鱼类 Hg 水平与人类活动影响地区野生鱼类观察到的 Hg 水平相当的主要生物学因素。δ(13)C 信号表明，浮游鱼类的 Hg 浓度较高，但未发现 Hg 浓度与营养水平之间存在关系。与之前报道的值相比，浮游动物和底栖端足类动物的 MeHg 百分比通常较高，这表明 MeHg 从水生食物网的基础有效地转移。本研究为干旱高海拔环境中鱼类 Hg 生物积累和水生食物网中 Hg 生物放大的地球化学和生物学控制提供了一些线索。
