Distribution of mercury in several environmental compartments in an aquatic ecosystem impacted by gold mining in northern Colombia.
Mercury (Hg) used in gold amalgamation is a major source of contamination in developing countries. Water, sediments, plankton, fish, and human samples from Grande Marsh, a Hg-polluted marsh located in the south of Bolívar, municipality of Montecristo, Colombia, were collected during both the rainy and the dry seasons (2003-2006), at three different sampling sites, and analyzed for total Hg (T-Hg) content. Water, sediment, seston, phytoplankton, and zooplankton T-Hg concentrations were 0.33 +/- 0.03 microg/L, 0.71 +/- 0.03, 1.20 +/- 0.06, 0.52 +/- 0.03, and 0.94 +/- 0.05 microg/g dry weight (wt), respectively. T-Hg levels in these compartments were highly pair-correlated (p < 0.05), and for all of them, except sediments, greater values were found during the dry season. Significant differences were observed for T-Hg concentrations in fish according to their trophic position. Average highest T-Hg values were found in carnivorous species such as Caquetaia kraussi (1.09 +/- 0.17 microg/g fresh wt), Hoplias malabaricus (0.58 +/- 0.05 microg/g fresh wt), and Plagioscion surinamensis (0.53 +/- 0.07 microg/g fresh wt), whereas the lowest were detected in noncarnivorous species such as Prochilodus magdalenae (0.157 +/- 0.01 microg/g fresh wt). In those fish species where seasonal comparisons were possible, specimens captured during the dry season had greater T-Hg levels in muscle. Although the T-Hg mean level for all fish samples (0.407 +/- 0.360 microg/g fresh wt) did not exceed the recommended limit ingestion level, risk assessment based on the hazard index suggested that a fish intake of 0.12 kg per day (a small carnivorous specimen) could increase the potential health effects related to Hg exposure in the local human population, whose hair T-Hg median value was 4.7 microg/g, and presented a low but significant correlation with fish consumption (r = 0.250, p = 0.016). In short, Hg pollution from gold mining around Grande Marsh has permeated the food web, and currently levels in fish represent a serious concern for human health.
Marrugo-Negrete
Jose
J
Water, Applied and Environmental Chemistry Group, University of Córdoba, Montería, Colombia.
Benitez
Luis Norberto
LN
Olivero-Verbel
Jesús
J
D000704:Analysis of Variance; D000818:Animals; D003105:Colombia; D005260:Female; D005399:Fishes / Q000378:metabolism*; D020387:Food Chain; D005506:Food Contamination / Q000032:analysis; D005618:Fresh Water / Q000032:analysis; D019015:Geologic Sediments / Q000032:analysis; D006046:Gold; D006801:Humans; D008297:Male; D008628:Mercury / Q000378:metabolism*; D008906:Mining; D010839:Phytoplankton / Q000378:metabolism; D012621:Seasons; D014877:Water Pollution, Chemical / Q000032:analysis*; D053833:Wetlands; D015048:Zooplankton / Q000378:metabolism
D006046:Gold; D008628:Mercury