ABSTRACT
The presence of polycyclic aromatic hydrocarbons (PAHs) in the environment is of major concern since some of these compounds are highly persistent, toxic (causing cancer) and wide spread pollutants. The objective of this study was to evaluate the levels of PAHs in sediment samples collected from Blood and Mokolo Rivers in Limpopo Province, South Africa. The PAHs in sediments were extracted using optimized microwave-assisted extraction (MAE) method. The quantification of sixteen (16) PAHs in sediments was done by gas chromatography-flame ionization detector (GC-FID). The levels of PAHs recorded in sediment samples from Blood River ranged between 0.015 and 3.25 mg kg-1. The concentrations of PAHs obtained in sediments from Mokolo River (0.047 to 52.7 mg kg-1) were higher than those recorded in sediments from Blood River. The PAHs ratios indicated that both pyrogenic and petrogenic could be the sources of these compounds in both rivers. Toxic equivalency factors (TEFs) and benzo(a)pyrene equivalent (BaPE) were used to estimate the potential human health risk of PAHs in quantitative terms. The assessment of ecotoxicological risk indicated that the sediment samples collected from Mokolo River are at high toxicity risk while sediments from Blood River are at low sediment toxicity risk.
Subject(s)
Geologic Sediments/chemistry , Polycyclic Aromatic Hydrocarbons/analysis , Rivers/chemistry , Water Pollutants, Chemical/analysis , Benzo(a)pyrene/analysis , Benzo(a)pyrene/toxicity , Environmental Monitoring , Humans , Polycyclic Aromatic Hydrocarbons/chemistry , Polycyclic Aromatic Hydrocarbons/toxicity , Risk Assessment , South Africa , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/toxicityABSTRACT
Samples of coal were collected from different seams at a South African coal mine and comparative leaching experiments were carried out under various pH conditions and times to investigate the leaching behavior and potential environmental impact of possibly hazardous elements such as As, Cd, Co, Cr, Mn, Ni, Pb, Th and U. The calculated leaching intensities, sequential extraction results and cumulative percentages demonstrate that the leaching behavior of the elements is strongly influenced by the pH, the leaching time and the properties and occurrences of the elements. The leached concentrations of As, Cd, Co, Cr, Mn, Ni and Pb exceeded the maximum concentrations recommended by the Environmental Protection Agency (EPA) for surface water.
