[Soil Heavy Metal Content, Pollution, and Influencing Factors in Typical Farming Area of Sichuan Basin].

In order to identify heavy metal contents, the pollution characteristics and influencing factors of soil in typical farming areas in the Sichuan basin were analyzed, with Jiangjin District of Chongqing City chosen as the study area. Two hundred and forty-seven topsoil samples were collected and analyzed using the Nemerow index (NPI), geographical information system (GIS), and geodetector method. The results demonstrated that: 1 the arithmetic means of Cd, Cu, and Zn in the topsoil were 1.22, 1.10, and 1.98 times that of the soil background values in western Chongqing, respectively. 2 The high-value areas of the six heavy metals were mainly distributed in the northern, western, and central Jiangjin district, whereas the low-value areas were distributed in the eastern and southern Jiangjin district. 3 The NPI showed that the polluted sample points accounted for 22.1% of the total sample points, indicating that the overall soil pollution was mainly safety and vigilance in general. The high value of NPI was distributed in Dingshan street in the northern Jiangjin district. 4 The explanatory power of stratum on the distribution of heavy metal contents in the topsoil was the strongest, followed by that of the topographic factor. The interaction effect of the stratum and topographic factors on the distribution of heavy metal content in soil was the strongest. The results showed that the stratum and topographic factors were the key factors affecting the distribution of soil heavy metal contents in the study area.

[Effect of Land Use/Land Cover Change on the Concentration of Se and Heavy Metals in Soils from a "Return Cropland to Forest" Area, Southwest China].

Human activities (land use) and environmental change (land cover change) affect the concentration of Se and heavy metals in soils. The implementation of the "Return Cropland to Forest (RCF)" ecological project has changed the land use and cover, which has provided an ideal experimental area for studying the effects of land use and cover change on selenium (Se) and heavy metals in the soil. In this study, 91 top soil samples from different land use and land cover types, including dry land, paddy land, natural forest land, and secondary forest land, were collected, and the contents of Se, heavy metals, and soil organic matter (SOM) and pH were analyzed. The results showed that:① the average values of ω(Se) (0.42×10-6), ω(As) (13.0×10-6), and ω(Sb) (1.03×10-6) were higher than the soil background values of western Chongqing. ② The concentrations of Se, Cd, Cr, Ni, Pb, and Zn in soils from secondary forest land were significantly higher than those from dry land soils, suggesting that the Se and heavy metals might have significantly increased in the surface soil after the implementation of the RCF ecological project. ③ The SOM was the key controlling factor for the enrichment and distribution of Se and heavy metals in the top soils. Our results indicated that the land use and land cover change would deeply impact the concentrations of Se and heavy metals in the top soils via influencing the soil properties, especially the SOM.

NRN1 and CAT Gene Polymorphisms, Complex Noise, and Lifestyles interactively Affect the Risk of Noise-induced Hearing Loss.

OBJECTIVE: The effects of interactions between genetic and environmental factors on the noise-induced hearing loss (NIHL) are still unclear. This study aimed to assess interactions among gene polymorphisms, noise metrics, and lifestyles on the risk of NIHL. METHODS: A case-control study was conducted using 307 patients with NIHL and 307 matched healthy individuals from five manufacturing industries. General demographic data, lifestyle details, and noise exposure levels were recorded. The Kompetitive allele-specific polymerase chain reaction (KASP) was used to analyze the genotypes of 18 SNPs. RESULTS: GMDR model demonstrated a relevant interaction between NRN1 rs3805789 and CAT rs7943316 (P = 0.0107). Subjects with T allele of rs3805789 or T allele of rs7943316 had higher risks of NIHL than those with the SNP pair of rs3805789-CC and rs7943316-AA (P < 0.05). There was an interaction among rs3805789, rs7943316, and kurtosis (P = 0.0010). Subjects exposed to complex noise and carrying both rs3805789-CT and rs7943316-TT or rs3805789-CT/TT and rs7943316-AA had higher risks of NIHL than those exposed to steady noise and carrying both rs3805789-CC and rs7943316-AA (P < 0.05). The best six-locus model involving NRN1 rs3805789, CAT rs7943316, smoking, video volume, physical exercise, and working pressure for the risk of NIHL was found to be the interaction (P = 0.0010). An interaction was also found among smoking, video volume, physical exercise, working pressure, and kurtosis (P = 0.0107). CONCLUSION: Concurrence of NRN1 and CAT constitutes a genetic risk factor for NIHL. Complex noise exposure significantly increases the risk of NIHL in subjects with a high genetic risk score. Interactions between genes and lifestyles as well as noise metrics and lifestyles affect the risk of NIHL.