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Environ Res. 2015 Jul;140:191-7. doi: 10.1016/j.envres.2015.03.029. Epub 2015 Apr 9.

Mercury in fish of the Madeira river (temporal and spatial assessment), Brazilian Amazon.

Author information

1
Laboratório de Biogeoquímica Ambiental, Universidade Federal de Rondônia, Brazil. Electronic address: bastoswr@unir.br.
2
Faculdade de Ciências da Saúde, Universidade de Brasília, Brazil.
3
Instituto de Química, Universidade de Brasília, Brazil.
4
Laboratório de Biogeoquímica Ambiental, Universidade Federal de Rondônia, Brazil.
5
Laboratório de Biogeoquímica Ambiental, Universidade Federal de Rondônia, Brazil; Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil.
6
Laboratório de Biogeoquímica Costeira, Instituto de Ciências do Mar, Universidade Federal do Ceará, Ceará, Brazil.
7
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil.

Abstract

The Madeira River is the largest tributary of the Amazon River Basin and one of the most impacted by artisanal gold-mining activities, deforestation for agricultural projects, and recent hydroelectric reservoirs. Total Hg (and methylmercury-MeHg) concentrations was determined in 3182 fish samples of 84 species from different trophic levels as a function of standard size. Species at the top of the trophic level (Piscivorous, Carnivorous) showed the highest mean total Hg concentrations (51-1242 µg/kg), Planctivorous and Omnivorous species showed intermediate total Hg concentrations (26-494 µg/kg), while Detritivorous and Herbivorous species showed the lowest range of mean total Hg concentrations (9-275 µg/kg). Significant correlations between fish size (standard length) and total Hg concentrations were seen for Planctivorous (r=0.474, p=0.0001), Piscivorous (r=0.459, p=0.0001), Detritivorous (r=0.227, p=0.0001), Carnivorous (r=0.212, p=0.0001), and Herbivorous (r=0.156, p=0.01), but not for the Omnivorous species (r=-0.064, p=0.0685). Moreover, fish trophic levels influenced the ratio of MeHg to total Hg (ranged from 70% to 92%). When adjusted for standard body length, significant increases in Hg concentrations in the last 10 years were species specific. Spatial differences, albeit significant for some species, were not consistent with time trends for environmental contamination from past alluvial gold mining activities. Fish-Hg bioaccumulation is species specific but fish feeding strategies are the predominant influence in the fish-Hg bioaccumulation pattern.

KEYWORDS:

Amazonia; Fish; Gold mining; MeHg; Rio Madeira

PMID:
25863592
DOI:
10.1016/j.envres.2015.03.029
[Indexed for MEDLINE]

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