[Characteristics and Identification Priority Source of Heavy Metals Pollution in Farmland Soils in the Yellow River Basin].

Assessments of the soil environmental quality of farmland and pollution source apportionment are the foundation for ensuring national food security and agricultural sustainable development, as well as an important prerequisite for the pursuit to keep our lands clean. This study evaluated the characteristics of heavy metal pollution in farmland soils in the Yellow River Basin from 2000 to 2023, based on the data of heavy metal contents including As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, using the geo-accumulation index method. Source apportionment was conducted by employing a positive matrix factorization (PMF) model. The probabilistic health risks were evaluated by coupling Monte Carlo simulation with a human health risk assessment model, and priority pollution sources and elements were identified. The results showed that:① the average content of all heavy metals in farmland soils within the study area was lower than the screening values specified in the soil environment quality risk control standard for soil contamination of agriculture land (GB 15618-2018) (pH>7.5). However, the contents of Cd, As, and Zn in the samples exceeded their screening values, with percentages of 21.69%, 5.56%, and 1.23%, respectively, with Cd having the highest rate of exceedance. ② Hg and Cd were moderately polluted, Cu and Pb were slightly polluted, and the other elements were not polluted. ③ The main sources of heavy metals in farmland soil were traffic-industrial sources, natural-agricultural sources, industrial-natural sources, and agricultural-industrial sources, with contribution rates of 37.04%, 26.69%, 21.72%, and 14.55%, respectively. ④ Heavy metals in farmland soil posed carcinogenic health risks to adults and children but did not have non-carcinogenic risks; As and Cd were priority control elements for human health risks, and industrial-natural sources and agricultural-industrial sources were priority control sources in the study area.

[Refined Assessment of Exposure and Health Risks of Heavy Metals in Water for the Children in Xigu District, Lanzhou].

Water is an important pathway for human exposure to heavy metals. Accurate assessment of the health risks that are related to exposure to heavy metals in drinking and household water are required for the preparation of targeted health risk prevention measures. This study explores and identifies the health risks related to exposure to heavy metals via drinking and household water pathways in Xigu District, Lanzhou, northwestern China, using household water samples and survey data obtained during July-September 2015 (wet season) and December 2015-January 2016 (dry season). During each period, drinking water and household water that were available for use by children aged 0-5 and 6-17 years were sampled and a questionnaire on water-related behavior patterns was completed for each household. Cd, Cr, Pb, and As concentrations were analyzed in all water samples, and were used along with water-related exposure factors from the questionnaires to estimate exposure doses and associated health risks using models recommended by the United States Environmental Protection Agency (US EPA). The results showed that the concentrations of Cd, Cr, Pb, and As in both drinking and household water samples did not exceed the relative thresholds defined in China's national water quality standards. The concentrations of heavy metals in household water were more affected by seasonal factors than of those of drinking water. The non-cancer and cancer risks were in the ranges of 2.82×10-8-2.43×10-2 and 7.55×10-9-3.62×10-5, respectively, which are within acceptable levels, although the non-cancer and cancer risks from drinking water were both higher than of those determined for household water. Furthermore, the non-cancer and cancer risks from household water for children aged 0-5 years were lower than of those for children aged 6-17 years in each period. However, the cancer risk from drinking water for children aged 0-5 years was lower than of that for children aged 6-17 years, whereas the reverse was found for non-cancer risks. This study indicates that Cd, Cr, Pb, and As in drinking and household water did not pose significant detrimental effects to human health, and that the refined exposure assessment used could reduce uncertainties in health risk assessments.

[Source and health risk assessment of heavy metals in ambient air PM10 from one coking plant].

To investigate the sources and health risk of heavy metals in ambient air PM10 from the coking plant, the PM10 in the air around one coking plant was collected in June 2012. Then the heavy metals concentrations in PM10 were tested by the microwave-ICP-MS method. Furthermore, the USEPA's human exposure assessment model was applied to preliminarily evaluate the human health risks of the heavy metals in air particulate matter. The results show that the concentrations of 10 kinds of heavy metals in PM10 from the coking plant vary significantly, ranging from 3.06 x 10(-5) mg x m(-3) to 1.77 x 10(-2) mg x m(-3), of which the concentration of Cr is the highest, while the concentration of Co is the lowest, and the concentration of the carcinogenic substances is higher than that of the non-carcinogenic substances. The coking plant is identified to be the major source of the heavy metals in ambient air PM10, and Ni is the main polluting heavy metal. Moreover, the heavy risk assessment results reveal that the carcinogenic risks for adults are higher than children, while the carcinogenic risks in industrial areas and school relatively large. The non-carcinogenic risks for children are the highest in all the population, and the non-carcinogenic risks in residential area can not be ignored. Among the carcinogenic substances, the potential carcinogenic risks of Cd, Cr and As are comparatively large, Ni and Co have certain potential risks. Whereas, among the non-carcinogenic substances, the non-carcinogenic risks of Mn is great. Consequently, relevant departments should pay close attention to this situation.