Soil contamination assessment for Pb, Zn and Cd in a slag disposal area using the integration of geochemical and microbiological data

Abstract

Improper disposal of mining waste is still considered a global problem, and further details on the contamination by potentially toxic metals are required for a proper assessment. In this context, it is important to have a combined view of the chemical and biological changes in the mining dump area. Thus, the objective of this study was to evaluate the Pb, Zn and Cd contamination in a slag disposal area using the integration of geochemical and microbiological data. Analyses of soil organic matter (SOM), pH, Eh, pseudo-total concentration of metals, sequential extraction and microbial community by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) were conducted. Metal availability was evaluated based on the geoaccumulation index (I ), ecological risk ([Formula: see text]), Risk Assessment Code (RAC) and experimental data, and different reference values were tested to assist in the interpretation of the indices. The soil pH was slightly acidic to neutral, the Eh values indicated oxidized conditions and the average SOM content varied from 12.10 to 53.60 g kg. The average pseudo-total concentrations of metals were in the order of Zn > Pb > Cd. Pb and Zn were mainly bound to the residual fraction and Fe-Mn oxides, and a significant proportion of Cd was bound to the exchangeable and carbonate fractions. The topsoil (0-20 cm) is highly contaminated (I ) with Cd and has a very high potential ecological risk ([Formula: see text]). Higher bacterial diversity was mainly associated with higher metal concentrations. It is concluded that the integration of geochemical and microbiological data can provide an appropriate evaluation of mining waste-contaminated areas.

Geographic distribution of cadmium and its interaction with the microbial community in the Longjiang River: risk evaluation after a shocking pollution accident

“…All fractions (except the residual fraction) can become available to biota under changing environmental conditions 8 . Cd also exists in different fractions in different environments, e.g., a significant proportion of the Cd was bound to the exchangeable and carbonate fractions in a slag disposal area 9 , the acid-soluble fraction (carbonates) and Fe oxide bound in a former mining area 10 , the carbonate (Na2EDTA) fraction in sewage sludge-amended soils 11 , the redox-sensitive fractions in wet and anoxic sediment 12 , and the residual fraction in agricultural soils 13 and sediments of a Mexican reservoir 14 . The stability of Cd in different environments differed with its existence form.…”

Adsorption of lead (Pb) in strongly weathered tropical soil (Ribeira Valley region - Brazil)

“…The Ribeira Valley (Ribeira de Iguape water basin and Cananéia-Iguape estuarine complex) is a well-known region due to its historic Pb exploitation. The improper disposal of Pb slags in the soils and the upper Ribeira de Iguape river led to the contamination of many municipalities downstream, including the Cananéia-Iguape estuarine complex (Bosso and Enzweiler, 2002;Guimarães and Sígolo 2008;Rodrigues et al, 2012;Mahiques et al, 2013;Piedade et al, 2014;Kasemodel et al, 2016;Tramonte et al, 2016). There is a necessity of proper landfill implantation for the mining waste.…”

Assessment of the use of tropical peats as local alternative materials for the adsorption of Pb, Zn and Cd: An equilibrium study

“…Pb, Zn and Cd are PTEs frequently present in areas contaminated by industrial and mining activities (Kasemodel et al, 2016;Marques et al, 2019). Pb is a toxic element that is nonessential and has the potential to accumulate in humans, affecting fundamental biochemical processes; it has the ability to imitate Ca and consequently inhibit Ca-protein interactions (ATSDR, 2007).…”