Mercury in the gold mining district of San Martin de Loba, South of Bolivar (Colombia)

Water, floating macrophytes, and sediments from effluents near mining sites also had high Hg values. In mines of San Martin de Loba and Hatillo de Loba, for instance, the geoaccumulation index (I_geo) for sediments reached values greater than 6, indicating extreme pollution. In short, these data support the presence of a high Hg-polluted environment in this mining district, with direct risk for deleterious effects on the health of the mining communities.
http://link.springer.com/article/10.1007%2Fs11356-014-3724-8