Avaliação da contaminação do ar e água por mercúrio e seus possíveis impactos ambientais em zonas de mineração de ouro na Província de Tete nos Distritos de Chiúta e Moatize

Abstract

Mercury is a heavy metal that poses a major threat to the environment and human health, even in low concentrations, with human activities being the main source of introduction of this metal into the environment. For contamination analysis, water samples were collected in 9 locations in plastic containers and collected at a depth ranging from 20 to 30 m. Mercury concentrations in water and air were determined using a LUMEX RA-915M mercury analyzer coupled to the RP-92. The results of this study demonstrate that the waters of the Chiúta and Moatize basins are contaminated by mercury, but only in Chiúta in the town of Cató were values ​​above those established by Decree-Law No. 67/2010 - Regulation on Environmental Quality Standards and Effluent Emissions (2,000 ng/L) obtained, sampling points 10 and 11 with Hg levels ranging from 4,170.67±9.40 and 2,453.00±8.96 ng/L, respectively and The remaining sampling sites (Machinga and Cató villages for Chiúta and Nhamtamula and Kanchoere villages) presented values ​​below 44.94±10.29 to 1,587.20±11.68 ng/L. Mercury was detected in well water in both districts; contamination levels at all sampling points in Moatize and Chiúta were below 1,000 ng/L, a value established by ministerial decree no. 180/2004 of 15 September for water intended for human consumption, ranging from 0.17±0.38 to 23.97±3.76 ng/L and 32.50±8.64 to 154.57±7.01 ng/L, respectively. Regarding mercury levels in well water, it was observed that practically all sampling points presented contamination by Hg, which varied from 0.67±1.43 to 31.00±2.48 for Moatize and from 2.90±1.27 to 51.33±7.59 ng/L for Chiúta. These values ​​are below those established by ministerial decree no. 180/2004 of 15 September. Furthermore, Hg levels in the air varied from 0 to 3,170 ng/m3, where most points were above 25 ng/m3, the value recommended by the World Health Organization for workplaces, except for points 2, 3, and 8 where the values ​​detected were below 25ng/m3. And there was a point where the concentration of Hg was more than 15 times higher than the others. After the analysis, the results of the study allowed us to conclude that the water and air present mercury levels above the maximum limits established in most points.(TRADUÇAO NOSSA)