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PM2.5 pollution raises environmental concern in China and other countries worldwide. The marker technique is regarded as a reliable tool for atmospheric aerosol source tracing. Cellulose can be used as a marker to identify and evaluate vegetative detritus emission to primary aerosols. An analytical method for cellulose in the PM2.5 has been modified because of its low content in PM2.5 and the relative high procedure blank. The method combines an enzymatic cellulose hydrolysis procedure and a GOD-phenol-4-aminoantipyrene determination of formed glucose. The key parameters of the method were optimized as a delignification condition, temperature for cellulose enzymatic hydrolysis, amount of enzyme, pH value and hydrolysis reaction time. The method meets the requirements of cellulose determination of PM2.5 with a detection limit of 0.26 μg/m3. A procedure blank of 36.5 μg glucose was obtained which is significantly lower than 53.8 μg for the previous method. Cellulose in 23 Beijing urban PM2.5 collected from May 15th to June 28th, 2012 were analyzed. The detection rate of cellulose is 96%. The results show that the cellulose concentration in Beijing PM2.5 is (0.573±0.17) μg/m3. The vegetative detritus contribution is 1.37%±0.65% of PM2.5 mass concentration, or 4.4% in average and 9.2% in the maximum of PM2.5 organic carbon, indicating vegetative detritus is a major contributor of urban aerosol organic carbon and has to be considered in source attribution studies. This method provides a new technique for urban atmospheric PM2.5 source identification.

Objective: We conducted a case-control study by genotyping three potential functional SNPs to assess the association of Xeroderma pigmentosum complementation group F (XPF) polymorphisms with gastric cancer susceptibility, and role of XPF polymorphisms in combination with H.pylori infection in the risk of gastric cancer., Methodology: A hospital case-control study was conducted. A total of 331 patients with gastric cancer and 355 controls were collected. Three SNPs of XPF, XPF rs180067, rs1799801 and rs2276466, were genotyped by Taqman real-time PCR method with a 7900 HT sequence detector system., Results: The gastric cancer patients were more likely to have smoking habit, a family history of cancer and H.pylori infection. We did not find the significant difference in the genotype distributions of XPF rs180067, rs1799801 and rs2276466 between cases and controls. Multivariate logistic analysis showed a non-significant decreased risk in patients carrying rs180067 G allele, rs1799801 T allele or rs2276466 T allele genotypes. The stratification by H.pylori infection was not significantly different in polymorphisms of XPF rs180067, rs1799801 and rs2276466., Conclusion: There was no evidence that polymorphisms in rs180067, rs1799801 and rs2276466 significantly affect the risk of gastric cancer. Further large sample size studies are strongly needed to validate their association.

From 18 September 2005 to 13 September 2006 in Beijing, 166 TSP samples were collected at three sites in southern suburb, downtown and northern suburb, respectively. Lead and other 28 elements were determined for those samples by ICP-AES and ICP-MS methods. The lead average concentration of one year in southern suburb, downtown and northern suburb was 179, 142 and 102 ng x m(-3), respectively. Source identification and apportionment were carried out using absolute principal component analysis (APCA) method. Five groups of sources were recognized. The sources are nonferrous metallurgy (55.6%), coal combustion (16.9%), construction dust (11.8%) and soil dust (10.2%), respectively. Major sources of aerosol lead in Beijing were from nonferrous metallurgy industry. Lead associated with coal combustion and other sources were evenly distributed over three sites. However, industrial leadwas apparently at different levels at three sites, higher in southern suburb and lower in northern suburb. The lead concentration originated from nonferrous metallurgy at three sites from southern suburb, downtown to northern suburb was 113, 77.0 and 44.2 ng x m(-3), respectively, implying that the major sources for industrial lead were from the south to the Beijing. There is considerable space for reduction of aerosol lead concentration in Beijing. The main object for lead pollution discharge reduction and environmental management measures should aim at nonferrous metallurgy, especially for the field of lead metallurgy located at the south area to the Beijing. The calculation result based on the same chemical analysis data also shows that major source for TSP in Beijing is of soil dust and construction dust, accounting for 72.3%. The other sources such as coal combustion and nonferrous metallurgy account for 13.4% and 9.5%, respectively.