Dynamics of (total and methyl) mercury in sediment, fish, and crocodiles in an Amazonian Lake and risk assessment of fis
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Dynamics of (total and methyl) mercury in sediment, fish, and crocodiles in an Amazonian Lake and risk assessment of fish consumption to the local population Diego Ferreira Gomes & Raquel Aparecida Moreira & Nathalie Aparecida Oliveira Sanches & Cristiano Andrey do Vale & Michiel Adriaan Daam & Guilherme Rossi Gorni & Wanderley Rodrigues Bastos
Received: 8 August 2019 / Accepted: 1 January 2020 # Springer Nature Switzerland AG 2020
Abstract Increasing concerns have been raised about the toxicity of mercury (Hg) to humans, especially for those that consume a great amount of fish. High Hg concentrations have previously been measured in Amazonian waterbodies, both resulting from natural and anthropogenic sources. However, few studies have been conducted so far in Amazonian lakes that are fished by local populations. In addition, few of those studies included methylmercury (MeHg), the most toxic and bioaccumulative Hg form, and evaluated the influence D. F. Gomes (*) : W. R. Bastos Department of Ecology and Evolutionary Biology, Federal University of São Carlos, Rod. Washington Luís km 235 - SP-310, São Carlos, São Paulo 13565-905, Brazil e-mail: [email protected] R. A. Moreira NEEA/CRHEA/SHS, São Carlos Engineering School, University of São Paulo, Av. Trabalhador São Carlense, 400, São Carlos 13560-970, Brazil N. A. O. Sanches : G. R. Gorni Postgraduate Program in Territorial Development and Environment, University of Araraquara, Carlos Gomes, Araraquara, SP 14801-340, Brazil C. A. do Vale Chico Mendes Institute for Biodiversity Conservation, Resex Lago do Cuniã, Avenida Lauro Sodré, 6500, Porto Velho, RO 76803-260, Brazil M. A. Daam CENSE, Department of Environmental Sciences and Engineering, Faculty of Sciences and Technology, New University of Lisbon, Quinta da Torre, 2829-516 Caparica, Portugal
of physico-chemical conditions and season on Hg dynamics. In the present study, total Hg (THg) and MeHg concentrations were measured in bottom sediment as well as in two fish and two crocodile species of the Amazonian Cuniã Lake. Bottom sediment MeHg concentrations were higher in the dry season than in the wet season, which is related to differences in physicochemical (pH and electrical conductivity) conditions. Diet appeared to be related with animal tissue MeHg concentrations, with the herbivorous fish having lower MeHg levels than the predatory fish and crocodiles. Based on the measured tissue concentrations and published data on local person weight and fish consumption, MeHg risk to Cuniã Lake populations was estimated. Although the MeHg fish tissue concentrations did not exceed national and international standards, a significant risk to the local population is anticipated due to their high fish consumption rates.
Keywords Methylmercury . Human risk assessment . Environmental distribution . Bioaccumulation . Amazon
Introduction Concerns on mercury (Hg) toxicity initiated in the 1950s when severe health effects were noted in humans through consumption of fish contaminated with chemical waste released by the Ch
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