Evaluation of Environmental Risk of Metal Contaminated Soils and Sediments Near Mining Sites in Aguascalientes, Mexico

Multi-Indices Assessment of Origin and Controlling Factors of Trace Metals in River Sediments from a Semi-Arid Carbonated Basin (the Sebou Basin, Morocco)

River water quality is particularly of concern in semi-arid countries with limited water resources. Increasing anthropogenic activities can lead to the accumulation of trace metals (TM) in bottom sediments, which is a specific storage compartment. The present study aimed to investigate the geochemistry of trace metals (As, Cd, Co, Cr, Cu, Ni, Pb, Zn) and of some physico-chemical parameters in bottom sediments from the Sebou basin, which represents 1/3 of the surface water resources of Morocco. The order of abundance of the metals was Zn > Cr > Cu > Ni > Pb > Co > As > Cd. A major fingerprint of weathering on metal concentration, and point and non-point anthropogenic sources were highlighted. The origin and intensity of the contamination were determined using a combination of geochemical indicators. The contamination was on the whole moderate, with Cr, Zn, Cu, and Pb as the most enriched metals, especially at the A1, S3, and S4 stations located downstream of Fez city, well known for its intensive industrial and tannery activities. A multi-variate analysis evidenced the strong link between natural elements such as Co with clays and Fe oxides, and As with Ca, whereas Cd, Cu, Cr, Ni, Pb, Zn, partly originating from anthropogenic activities (industrial and domestic waste, agricultural inputs), were linked to phosphorus, oxides, carbonates, and/or POC, indicating their anthropic source and/or control by sediment compounds. Cadmium, Pb, and Cu were the most available metals. Finally, in addition to Cd, Pb and Zn were identified as hazardous metals in sediments as evidenced by the positive relationship between the proportion of the labile fraction and the enrichment factor revealing anthropogenic inputs.

Pollution indices and sources appointment of heavy metal pollution of agricultural soils near the thermal power plant

Alluvial soils of valleys of the Danube and Mlave rivers represent priority development areas with favorable conditions for life, agriculture and tourism in eastern Serbia. Operation of the thermal power plant Kostolac results in the emission of potentially toxic pollutants into the air, water and land. The goals were to determine the soil pollution with inorganic pollutants using different pollution indices, to identify of the sources of pollutants by means of principal component analysis and the loading of each factor for individual element assessed by multi-linear regression analyses. Chemical characteristics of the studied area resulted in division of the area into four impact zones upon the distance from main pollutants (power plant blocks and ash disposal dumps). There was no established soil pollution with potentially toxic elements in bulk of the agricultural territory. Two principal components (PC1 and PC2) explained about 73% of variance. Three studied elements (As, Cu and Pb) showed anthropogenic origin of their most concentrations in soil, while other elements (Cd, Co, Cr, Ni and Zn) were of a natural (geological) origin. Single pollution index showed moderate pollution level by Ni. Integrated Nemerow pollution index showed low to no pollution levels, indicating slight ecological risk. There were no established limitations for agricultural production in the studied area, except for the only spot polluted by As due to the great flooding event in the studied year.

Migration and speciation of heavy metal in salinized mine tailings affected by iron mining

The negative effects of heavy metals have aroused much attention due to their high toxicity to human beings. Migration and transformation trend of heavy metals have a close relationship with soil safety. Researching on migration and transformation of heavy metals in tailings can provide a reliable basis for pollution management and ecosystem restoration. Heavy metal speciation plays an important role in risk assessment. We chose Anshan tailings for our study, including field investigations and laboratory research. Four typical heavy metal elements of mine tailings {Fe (373.89 g/kg), Mn (2,303.80 mg/kg), Pb (40.99 mg/kg) and Cr (199.92 mg/kg)} were studied via Tessier test in vertical and horizontal direction. The main speciation of heavy metals in Anshan tailings was the residual. However, heavy metals have a strong ability for migration and transformation in vertical and horizontal directions. Its tendency to change from stable to unstable speciation results in increasing bioavailability and potential bioavailability. Fe, Mn, Pb and Cr showed different ability in the migration and transformation process (Mn > Pb > Fe > Cr) depending on the characteristics of heavy metals and physicochemical properties of the environment.