Determinação de metais pesados em amostras de solos da zona mineira de tantalite na aldeia de Morrua em Moçambique

Abstract

Mineral wealth in Mozambique has recently been more exploited by megaprojects mining, which consequently implies an increase in sources of release of heavy metals. It is important to be aware of the mechanisms of how these chemical elements migrate from rocks to soil, water and air, entering the food chain and thus affecting our health. The increase in metals heavy on our environment should be observed as a possible problem for the country, arising increased vulnerability to diseases linked to environmental pollution for the population living in vicinity of mining areas. Heavy metals were analyzed by ICP-OES, method validation was performed by using the reference materials SARM 46 and BCSS-1. According to the reference materials, it was obtained moderately accurate values ​​for Cr, Ni, Cu, Zn, Co of 2.8%, 2.1%, 2.9%, 3.1%, and 3.7%, respectively, for SARM 46 and 4.2%, 4.0%, 3.8%, 3.6%, and 3.8% for BCSS-1. Additionally, in the soil samples, it was possible to quantify the following heavy metals Ag, As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Tl, U, V and Zn using the same analytical method. There is no legislation in Mozambique on heavy metal limits to assess the level of contamination of samples from the study region, the levels of metals As, Cd, Cr, Cu, Ni, Pb, Zn were compared to the limits established by the World Health Organization (WHO). The metal contents in the samples range from 513 to 1549 mg/kg for arsenic, 21 to 159 mg/kg for cadmium, 109 to 347 mg/kg for chromium, 56 to 348 mg/kg for copper, 67 to 330 mg/kg for Nickel, 398 to 1570 mg/kg for lead and 53 to 197 mg/kg for Zinc. According to the limits prescribed by the WHO, all heavy metals analyzed in the soil samples are above the value limit established for soil considered unpolluted. Water and soil pollution compromises agriculture and food security, causing harm to the livelihoods of communities places. These data highlight the need for continuous monitoring and mitigation measures. to protect both the environment and the public health of communities affected by mining.(TRADUÇÂO NOSSA)