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

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Journal of Environmental Sciences 2010年第8期22卷 1171-1178页

作者： María Arribére María C Diéguez Sergio Ribeiro Guevara Claudia P Queimalios vesna fajon Mariana Reissig Milena Horvat 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

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.

关键词： Patagonia deep lakes total mercury plankton

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Relations between mercury fractions and microbial community components in seawater under the presence and absence of probable phosphorus limitation conditions

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Journal of Environmental Sciences 2019年第1期31卷 145-162页

作者： Igor ?ivkovi? vesna fajon Jo?e Kotnik Yaroslav Shlyapnikov Kristina Obu Vazner Ermira Begu Stefanija ?estanovi? Danijela ?anti? Ana Vrdoljak Slaven Jozi? Mladen ?oli? Jelena Lu?i? Jere Ve?a Grozdan Ku?pili? Marin Ordulj Frano Mati? Branka Grbec Natalia Bojani? ?ivana Nin?evi? Gladan Milena Horvat Department of Environmental Sciences Jo?ef Stefan Institute Jo?ef Stefan International Postgraduate School Ecological Engineering Institute Maribor 2000 Slovenia Laboratory of Marine Microbiology Institute of Oceanography and FisheriesSplit 21000 Croatia Laboratory of Chemical Oceanography and Sedimentology of the Sea Institute of Oceanography and FisheriesSplit 21000 Croatia Laboratory of Chemical Oceanography and Sedimentology of the Sea Institute of Oceanography and Fisheries Department of Marine Studies University of SplitSplit 21000 Croatia Laboratory of Physical Oceanography Institute of Oceanography and FisheriesSplit 21000 Croatia Laboratory of Plankton and Shellfish Toxicity Institute of Oceanography and FisheriesSplit 21000 Croatia

Microbial transformations of toxic monomethylmercury(MMHg) and dissolved gaseous mercury(DGM) at the lower levels of the marine food web are not well understood, especially in oligotrophic and phosphorus-limited seas. To examine the effects of probable phosphorus limitation(~PP-limitation) on relations between mercury(Hg) fractions and microorganisms, we determined the total mercury(THg), total methylated mercury(MeHg), DGM, and microbiological and chemical parameters in the Central Adriatic Sea. Using statistical analysis, we assessed the potential microbial effects on Hg transformations and bioaccumulation. Only in the absence of ~PP-limitation conditions(^(NO–P)P-limitation) is MeHg significantly related to most chemical and microbial parameters, indicating metabolism-dependent Hg *** heterotrophic activity of low nucleic acid bacteria(abundant in oligotrophic regions)seems responsible for most of Hg methylation under ^(NO–P)P-limitation. Under these conditions,DGM is strongly related to microbial fractions and chlorophyll a, indicating biological DGM production, which is probably not metabolically induced, as most of these relations are also observed underPP-limitation. MMHg biomagnification was observed through an increased bioaccumulation factor from microseston to mesozooplankton. Our results indicate that Hgtransformations and uptake might be enhanced under ^(NO–P)P-limitation conditions, emphasizing their impact on the transfer of Hg to higher trophic levels.

关键词： Mercury speciation Methylmercury Probable phosphorus limitation Microbial community

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