Spatial distribution of hg and as in rivers of the eastern amazon impacted by gold mining

Abstract

Human activities contribute to the contamination of rivers by toxic elements, causing serious effects on the health of traditional communities in the Amazon region. With the aim of verifying the spatial distribution of Hg and As concentrations in a region affected by gold mining in the Baú, Curuá, and Curuaés River basin, in the municipality of Altamira-PA, in the Brazilian Amazon, a study was carried out using geostatistical maps. The quantification of elements was performed using Inductively Coupled Plasma Emission Spectrometry with hydride generation (HGICP-OES). The obtained values were exported for use in computational processes with the QGIS and Surfer software, in order to produce isotheor maps. The results of the maps showed Hg concentrations that exceeded the limit established by the National Council for the Environment, which is 0.2 µg L-1. This indicates that the presence of mining in the region represents a threat to the ecosystem of these rivers. On the other hand, the maps for As showed that no station presented results that exceeded concentrations above the limit allowed for this element, which is 10 µg L-1. Based on these results, the geostatistical maps were effective in monitoring areas affected by toxic elements and can be used as a tool in the control of river water quality.