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Mercury in a stream-lake network of Andean Patagonia (Southern Volcanic Zone): Partitioning and interaction with dissolved organic matter
Chemosphere ( IF 8.8 ) Pub Date : 2018-01-12 , DOI: 10.1016/j.chemosphere.2018.01.048
Carolina Soto Cárdenas , María del Carmen Diéguez , Claudia Queimaliños , Andrea Rizzo , Vesna Fajon , Jože Kotnik , Milena Horvat , Sergio Ribeiro Guevara

Lake Nahuel Huapi (NH) is a large, ultraoligotrophic deep system located in Nahuel Huapi National Park (NHNP) and collecting a major headwater network of Northwestern Patagonia (Argentina). Brazo Rincón (BR), the westernmost branch of NH, is close to the active volcanic formation Puyehue-Cordón Caulle. In BR, aquatic biota and sediments display high levels of total Hg (THg), ranging in contamination levels although it is an unpolluted region. In this survey, Hg species and fractionation were assessed in association with dissolved organic matter (DOM) in several aquatic systems draining to BR. THg varied between 16.8 and 363 ng L−1, with inorganic Hg (Hg2+) contributing up to 99.8% and methyl mercury (MeHg) up to 2.10%. DOC levels were low (0.31–1.02 mg L−1) resulting in high THg:DOC and reflecting in high Hg2+ availability for binding particles (partitioning coefficient log Kd up to 6.03). In streams, Hg fractionation and speciation related directly with DOM terrestrial prints, indicating coupled Hg-DOM inputs from the catchment. In the lake, DOM quality and photochemical and biological processing drive Hg fractionation, speciation and vertical levels. Dissolved gaseous Hg (Hg0) reached higher values in BR (up to 3.8%), particularly in upper lake layers where solar radiation enhances the photoreduction of Hg2+ and Hg-DOM complexes. The environmental conditions in BR catchment promote Hg2+ binding to abiotic particles and bioaccumulation and the production of Hg0, features enhancing Hg mobilization among ecosystem compartments. Overall, the aquatic network studied can be considered a “natural Hg hotspot” within NHNP.



中文翻译:

安第斯巴塔哥尼亚(南部火山带)的河流-湖泊网络中的汞:与溶解有机物的分配和相互作用

纳韦尔瓦皮湖(NH)是位于纳韦尔瓦皮国家公园(NHNP)的大型超营养型深层系统,收集了西北巴塔哥尼亚(阿根廷)的主要上游水源网络。NH最西端的BrazoRincón(BR)靠近活跃的火山岩Puyehue-CordónCaulle。在BR,水生生物区和沉积物显示出高水平的总汞(THg),尽管处于无污染区域,但污染水平不一。在这项调查中,评估了几种向BR排放的水生系统中汞的种类和分离程度,以及与溶解有机物(DOM)的关系。THg在16.8至363 ng L -1之间变化,其中无机Hg(Hg 2+)占99.8%,甲基汞(MeHg)占2.10%。DOC水平低(0.31–1.02 mg L -1)产生高THg:DOC并反映出结合颗粒具有高Hg 2+利用率(分配系数log K d高达6.03)。在溪流中,汞的分馏和物种形成与DOM陆地印记直接相关,表明来自流域的Hg-DOM耦合输入。在湖泊中,DOM的质量以及光化学和生物处理推动了汞的分馏,形态形成和垂直水平。在BR中,溶解的气态Hg(Hg 0)达到更高的值(高达3.8%),特别是在湖上湖层,那里的太阳辐射增强了Hg 2+和Hg-DOM络合物的光还原作用。BR流域的环境条件会促进Hg 2+与非生物颗粒的结合以及生物富集和Hg 0的产生,具有增强生态系统区隔之间Hg动员的功能。总体而言,所研究的水生网络可被视为NHNP内的“天然汞热点”。

更新日期:2018-01-12
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