Ecological and contamination assessment of soil in the region of coal-fired thermal power plant

Elevated Uptake and Translocation Patterns of Heavy Metals in Different Food Plants Parts and Their Impacts on Human Health

Irrigation with contaminated wastewater is a common practice in cultivation of crops and vegetables in many developing countries due to the scarcity of available fresh water. The present study has investigated the transfer and mobilization trends of heavy metals in different crops and vegetables plants grown in contaminated soil and waterbody. The translocation patterns of metals from polluted sources into different organs of plants bodies such as roots and edible parts and associated health risks have been evaluated simultaneously. Total of 180 different environmental samples including food plants, agricultural soil, and irrigation water were collected and analyzed. Heavy metal concentrations (Fe, Ni, Mn, Pb, Cu, Cd, As) in water, soil, and different parts of crops and vegetable plants were compared with the permissible levels reported by FAO/WHO, EU, and USEPA. Different metals contents within the food plants were found to be in the order of Fe > Mn > Ni > Cu > Pb > Cd > As. Pollution load index (PLI) data indicate that soil is highly polluted with Cd as well as moderately contaminated by As and Cu. Bioconcentration factor (BCF) analysis showed excessive accumulation of some heavy metals in crops and vegetables. Target hazard quotient (THQ) and target carcinogenic risk (TCR) analysis data showed higher carcinogenic and non-carcinogenic risks for both adult and children from the consumption of metal-contaminated food items. The results of metal pollution index (MPI), estimated daily intake (EDI), and hazard index (HI) analyses demonstrated the patterns of metals pollution in different food plants.

The importance of using soil series-based geochemical background values when calculating the enrichment factor in agricultural areas

The enrichment factor (EF) is one of the most commonly used indices for determining the source of air, water and soil pollution. However, concerns have been raised about the accuracy of the EF results because the formula leaves the choice of background value to the researcher's discretion. The EF was used in this study to assess the validity of such concerns and to determine heavy metal enrichment in five soil profiles with different parent materials (alluvial, colluvial, and quartzite). Moreover, the upper continental crust (UCC) and specific local background values (sub-horizons) were used as the geochemical backgrounds. When UCC values were applied, the soils were moderately enriched in Cr (2.59), Zn (3.54), Pb (4.50) and Ni (4.69), and significantly enriched in Cu (5.09), Cd (6.54) and As (6.64). Using the sub-horizons of the soil profiles as a background value, it was found that the soils had "moderate enrichment" by As (2.59) and "minimally enrichment" by Cu (0.86), Ni (1.01), Cd (1.11), Zn (1.23), Cr (1.30), and Pb (1.50). As a result, the UCC reported an inaccurate conclusion indicating that soils were 3.84 times more heavily polluted than they were. In addition, the statistical analyses performed in this study (Pearson correlation analysis and principal component analysis) revealed that the percentage of clay in the soil horizons and the cation exchange capacity had strong positive relationships (r ≥ 0.670, p < 0.05) with certain heavy metals (Al, Zn, Cr, Ni, Pb and Cd). These findings indicated that sampling from the "lowest horizons" or "parent materials" of the soil series would yield the most accurate results in determining the geochemical background values in agricultural areas.