[Heavy Metal Contamination and Health Risk Assessment of Corn Grains from a Pb-Zn Mining Area].

A total of 92 corn grain samples, around the Pb-Zn mining area in Southwest China, were collected to evaluate the contamination and health risk of heavy metals. Heavy metals including Pb, Zn, Cd, Cr, and Ni in samples were analyzed. A single factor pollution index and comprehensive pollution index were calculated to assess the quality of corn grains. The potential health risks to adults and children due to the intake of these heavy metals through consumption of crops were evaluated using the health risk index. The results showed that the average contents of Pb, Zn, Cd, Cr, and Ni in corn grains were 0.30, 23.75, 0.21, 1.33, and 1.15 mg ·kg-1, respectively, Among the metals, the content of Zn, Pb, Cd, Cr, and Ni exceeded the national food hygiene standards. The Nemero index of Pb, Cd, Cr, and Ni ranged from 4.32 to 9.07, indicating an extremely high level, whereas the contamination of Zn reached an alarming level. The assessment results of the comprehensive health risk index for the corn grains indicated that the contamination of heavy metals poses health risks to adults and children by food ingestion; moreover, the children were more sensitive to various heavy metals than the adults. Principle component analysis revealed that the first main component dominated the sources of Pb, Cd, Cr, and Ni, while the second main component, Zn, might have originated from sources different from the other heavy metals. Positive correlations were not observed between the heavy metals in corns and soils.

[Principal Component Analysis and Ecological Risk Assessment of Heavy Metals in Farmland Soils around a Pb-Zn Mine in Southwestern China].

The farmland soil around a Pb-Zn mine in southwestern China was studied. One hundred forty-nine surface soil samples were taken from 0-20 cm depth, and the contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were tested. The correlations among these heavy metals were studied with multivariate analysis, and the potential sources of the metals were identified. The environmental risk of the metals was evaluated with the Potential Ecological Risk Index method. The results showed that the amounts of Cd, Pb, and Zn were at relatively high level, with average concentrations of 15.56, 419.4, and 933.4mg·kg-1 respectively, indicating the soil was heavily polluted. The average concentrations of Hg and As were 0.13 and 37.3mg·kg-1, suggesting moderate soil pollution. The average concentrations of Cu, Ni, and Cr were lower than Yunnan soil background values. The multivariate analysis suggested that the sources of Cd, Pb, Zn, Hg, and As were similar and came mainly from smelting activities in the mining area. The sources of Cu, Ni, and Cr were similar and can be attributed to natural sources. The comprehensive potential ecological risk index was 2294.8, which suggested a high potential ecological risk. In general, the farmland soils in the research area were polluted seriously by the mining and industrial activities.

Electrokinetic movement of multiple chlorobenzenes in contaminated soils in the presence of beta-cyclodextrin.

This study investigated the electrokinetic (EK) behavior of multiple chlorobenzenes, including 1,2,3,4-tetrachlorobenzene (TeCB), 1,2,4,5-tetrachlorobenzene (i-TeCB), and 1,2,3-trichlorobenzene (TCB) in contaminated clayed soils. The effect of beta-cyclodextrin (beta-CD) on the EK removal of the chlorobenzenes was studied. The largest removal was obtained when Na2CO3/NaHCO3 buffer was used as anodic purging solution without beta-CD. The removal efficiencies were related to the aqueous solubilities of chlorobenzenes. With the same cumulative electroosmotic flow, greater solubility led to higher removal efficiency. The addition of beta-CD inhibited the EK removal efficiency of all chlorobenzenes. The inhibition increased with the increase of beta-CD concentration. With the same beta-CD concentration, the inhibition increased with the rise of electric potential. It was found that the inclusion compounds between beta-CD and chlorobenzenzes were less soluble than chlorobenzenes. The formation of the less soluble inclusion compounds reduced the aqueous solubility of chlorobenzenes and led to the partial immobilization of the chlorobenzenes that desorbed from soil. It was feasible to use the EK technology to remove chlorobenzenes in contaminated soils using water as the anodic flushing solution. The addition of beta-CD was not recommended for the EK removal of chlorobenzenes.