Lu Z.,Oil and Gas Survey |
Lu Z.,Chinese Academy of Geological Sciences |
Rao Z.,National Research Center for Geo Analysis |
He J.,CAS Guangzhou Institute of Geochemistry |
And 7 more authors.
Journal of Asian Earth Sciences | Year: 2015
Headspace gases from cores are sampled in the gas hydrate drilling well DK-8 in the Qilian Mountain permafrost. Gas components and carbon isotopes of methane from headspace gas samples are analyzed. The geochemical features of the headspace gases along the well profile are compared with occurrences of gas hydrate, and with the distribution of faults or fractures. Their geochemical significance is finally pointed out in gas hydrate occurrences and hydrocarbon migration. Results show high levels of hydrocarbon concentrations in the headspace gases at depths of 149-167m, 228-299m, 321-337m and 360-380m. Visible gas hydrate and its associated anomalies occur at 149-167m and 228-299m; the occurrence of high gas concentrations in core headspace gases was correlated to gas hydrate occurrences and their associated anomalies, especially in the shallow layers. Gas compositions, gas ratios of C1/σC1-5, C1/(C2+C3), iC4/nC4, and iC5/nC5, and carbon isotopic compositions of methane (δ13C1, PDB‰) indicate that the headspace gases are mainly thermogenic, partly mixed with biodegraded thermogenic sources with small amounts derived from microbial sources. Faults or fracture zones are identified at intervals of 149-167m, 228-299m, 321-337m, and near 360-380m; significantly higher gas concentrations and lower dryness ratio were found in the headspace gases within the fault or fracture zones compared with areas above these zones. In the shallow zones, low dryness ratios were observed in headspace gases in zones where gas hydrate and faults or fracture zones were found, suggesting that faults or fracture zones serve as migration paths for gases in the deep layers and provide accumulation space for gas hydrate in the shallow layers of the Qilian Mountain permafrost. © 2014 Elsevier Ltd.
Liu X.-D.,Chinese Academy of Sciences |
Li J.,Chinese Academy of Sciences |
Li B.,National Research Center for Geo Analysis |
Yang H.-X.,National Research Center for Geo Analysis |
And 2 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2010
TSP samples were collected at three sites in southern suburb, downtown and northern suburb of Beijing from September 2005 to September 2006. 29 elements were determined using ICP-AES and ICP-MS. Based on meteorological data as well as air concentrations, spatial distributions and sources of TSP and its characteristics elements such as Al, Fe, Ca, S, Se, Pb, Zn under different wind directions were investigated. The concentrations averaged over sites for TSP as well as Al, Fe varied slightly for three wind directions; and concentrations at 3 sites demonstrated stepwise increasing trends along with the northeastlies. On the other hand, concentrations for typical heavy metals emitted from non-ferrous industry such as Pb and Zn were substantially higher when southwestlies prevail; and concentrations at 3 sites demonstrated stepwise decline trends along with the southwestlies. Pb, Zn and some heavy metals were most likely of atmospheric transport contribution from non-ferrous industrial emission in the region to the south of southern suburb of Beijing; whereas Al, Fe and other crustal elements were mainly from local sources of Beijing.
Gai N.,National Research Center for Geo Analysis |
Pan J.,National Research Center for Geo Analysis |
Yin X.C.,Qingdao University |
Zhu X.H.,National Research Center for Geo Analysis |
And 5 more authors.
Journal of Environmental Radioactivity | Year: 2015
Activities of atmospheric aerosols, bulk deposition fluxes, and undisturbed soil inventories of 7Be were investigated in China's East Asian monsoon zone at various latitudes ranging from 23.8°N to 43.5°N. The annual latitudinal distributions of 7Be concentrations in aerosols follow a distribution pattern which looks similar to a normal distribution with the maxima occurring in the mid-latitude region. Simultaneous measurements of 7Be at various latitudes suggest that atmospheric circulation may play an important role in the latitudinal distributions of 7Be in surface air. Latitude and wet precipitation are the main factors controlling the bulk 7Be depositional fluxes. Significant seasonal variations in 7Be depositional fluxes in Beijing, a mid-latitude city, were observed with the highest flux in summer and the lowest in winter, whereas less seasonality were found in the high- and the low-latitude cities. The highest 7Be inventory in undisturbed soils in summer also occurred at a mid-latitudinal area in the East Asian monsoon zone. Precipitation is the main factor controlling the 7Be soil inventory in Qingdao with the highest values occurring in autumn followed by summer. © 2015 Elsevier Ltd.