Mercury in an ultraoligotrophic North Patagonian Andean lake (Argentina): Concentration patterns in different components of the water column

作     者：María Arribére María C Diéguez Sergio Ribeiro Guevara Claudia P Queimalios Vesna Fajon Mariana Reissig Milena Horvat 

作者机构：LAAN-CNEA CAB Av. Bustillo Km 9.5 8400 Bariloche Argentina Laboratorio de Fotobiología INIBIOMA (Universidad Nacional del Comahue-CONICET) Department of Environmental Sciences Jozef Stefan Institute 

出 版 物：《Journal of Environmental Sciences》 (环境科学学报（英文版）)

年 卷 期：2010年第22卷第8期

页      面：1171-1178页

核心收录：

学科分类：08[工学] 081501[工学-水文学及水资源] 0815[工学-水利工程] 

基　　金：funded by the projects PICT 2005-33838 and PICT 2007-00393  Agencia Nacional de Promoción Científica y Tecnológica (Argentina)  and by IAEA TCPARG7007 

主　　题：Patagonia deep lakes total mercury plankton 

摘      要：The deep, ultraoligotrophic piedmont lakes of Northern Patagonia （Argentina） are located in pristine and barely impacted areas, along a wide latitudinal range. Several studies have reported moderate to high total mercury （Hg） concentrations and contrasting methylmercury （CH3Hg＋） production in different lake compartments. Sources of Hg for western Patagonian terrestrial and aquatic ecosystems are still not clear; while point sources can be ruled out and atmospheric deposition is a plausible source, along with contribution from active volcanic areas of the Andes. In this investigation, we reported a noticeably seasonal, spatial （between lake branches）, and vertical （between water column strata） heterogeneity in the total Hg concentrations found in the pelagic zone of Lake Moreno. Sterile water samples taken in a depth profile of the lake showed moderate to high concentrations of CH3Hg＋ in autumn with a decreasing trend with depth. Our results indicated that Hg is largely allocated in the plankton fraction between 10–53 μm; which dominated within the euphotic （epilimnetic） zone of the lake due to the high densities attained by two species of the dinoflagellate Gymnodinium. The 53–200 μm planktonic size fraction （comprising rotifers, ciliates and immature stages of crustaceans） and the 200 μm fraction （calanoid copepods and cladocerans） were found to bear strikingly lower total Hg concentrations, suggesting that the magnification of Hg at the planktonic consumer level is negligible.