Assessment of Arsenic, Lead, Mercury and Cadmium Pollution in Soils, Sediments and Mining Residues of the Lite-Bala Site Using the GRADSOD Approach

Abstract

This study evaluates the trace element contents (cadmium, lead, mercury and arsenic) in soils, sediments and rock residues of the artisanal gold mining site of Lite-Bala in the Democratic Republic of Congo. Random sampling, physi-cochemical analysis and analysis of total and soluble trace elements by ICP-OES spectrometry as well as calculations of pollution indices (FE and Igeo) and partition coefficient (kd) were carried out in two areas in the dry season and in the rainy season. The soils and sediments of the site are acidic, oxidizing, poor in organic carbon with clayey to sandy textures. Artisanal gold mining at Lite-Bala does not affect, to date, the cadmium, lead, mercury and arsenic contents of soils and sediments. On the other hand, the presence of these elements in rock residues, even in low levels, and the mechanization of this exploitation will have an impact on them in the long term; in particular for Hg used as an input and whose levels are close to the higher standard in surface soils.