Spatial distribution of health risks for residents located close to solvent-consuming industrial VOC emission sources

Emissions derived from the consumption of organic solvents have been proven to be the primary industrial source of volatile organic compounds(VOCs).In conjunction with epidemiologic studies, water-based paints(WBPs) and solvent-based paints(SBPs) were selected as representatives of newly developed solvents and traditional solvents, respectively,to simulate the effects of consuming solvents emitted during industrial production.And non-carcinogenic and carcinogenic risks to residents near emission sources were studied in detail.The results showed that the spatial distribution of health risks varied with meteorological conditions and type of emission source, and the prevailing wind direction strongly affected the distribution range and shape of the influenced area.The areas of influence maximized on heavy-polluting days for both WBP and SBP emission sources with the total span reaching 804 m and 16 km, respectively;meanwhile, the areas of influence for carcinogenic risk resulting from WBP emission sources were 1.2 and 2.3 times greater than those measured on fine and rainy days, respectively, and 1.8 and 2.9 times greater for SBP emission sources.Compared with WBPs, the total spans of negatively influenced regions resulting from SBP emission sources were 10.4, 12.5 and 19.9 times greater on fine, rainy and heavypolluting days, respectively.Therefore, carcinogenic risk was the dominant health threat for populations residing close to solvent-consuming industrial emission sources.The findings suggest that newly developed solvents are capable of significantly reducing consequent health threats, nevertheless, they could still pose occasional threats to nearby residents under specific meteorological conditions.

Effect of Silicon on Growth, Physiology, and Cadmium Translocation of Tobacco (Nicotiana tabacum L.) in Cadmium-Contaminated Soil

Silicon （Si） offers beneficial effect on plants under cadmium （Cd） stress such as promoting plant growth and increasing resistance to heavy metal toxicity. In this study, a pot experiment was performed to study the role of Si in alleviating Cd toxicity in tobacco （Nicotiana tabacurn L.） plants on a yellow soil taken from Guiyang, China. Nine treatments consisting of three concentrations of Cd （0, 1, and 5 mg kg^-1） together with three Si levels （0, 1, and 4 g kg^-1） were established. Plant growth parameters, Cd concentration, and the malondialdehyde （MDA）, chlorophyll, and carotenoid contents were determined 100 d after transplanting of tobacco seedlings. Application of exogenous Si enhanced the growth of tobacco plants under Cd stress. When 5 mg kg^-1 Cd was added, Si addition at 1 and 4 g kg^-1 increased root, stem, and leaf biomass by 26.1%-43.3%, 33.7% 43.8%, and 50.8% 69.9%, respectively, compared to $i addition at 0 g kg^-1. With Si application, the transfer factor of Cd in tobacco from root to shoot under both 1 and 5 mg kg^-1 Cd treatments decreased by 21%. The MDA contents in the Si-treated tobacco plants declined by 5.5% 17.1% compared to those in the non-Si-treated plants, indicating a higher Cd tolerance. Silicon application also increased the chlorophyll and carotenoid contents by 33.9% 41% and 25.8%-47.3% compared to the Cd only treatments. Therefore, it could be concluded that Si application can alleviate Cd toxicity to tobacco by decreasing Cd partitioning in the shoots and MDA levels and by increasing chlorophyll and carotenoid contents, thereby contributing to lowering the potential health risks of Cd contamination.