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Wang Y.,Guangxi University | Xue R.,Guangxi University | Li J.,Guangxi General Institute of Geology and Exploration | Zhu H.,Guangxi University | And 5 more authors.
Environmental Earth Sciences | Year: 2012

This study aims to explore the condensation and fractionation trends of persistent organic pollutants (POPs) in the karst soils. The tiankeng is a karst surface expression that can act as a focal point for introduction of contaminants to a karst aquifer, which may serve both as condenser for vapor phase POPs and as barrier/sink for particulate associated less volatile POPs. The fractionation of POPs in soils from the upper rim and floor of tiankeng is of interest in understanding the role of tiankeng in the long-distance transport of POPs. In the present study, polycyclic aromatic hydrocarbons (PAHs) in the surface soils from the upper rim and floor of Dashiwei tiankeng in Southern China were analyzed. The total PAH concentrations in soils were 23. 40-190 ng g -1, with phenanthrene being the most abundant. The distribution patterns of PAH compounds in the soil samples matched well with their properties. It indicated the heavy PAHs were susceptible to retention by the floor soils of tiankeng than light PAHs. A plot of Cfloor/Crim against PAH molecular weight gave a good positive relationship in the molecular weight range of 152-276. It is suggested that the floor soils can be focal points of more concentrated PAH and deserve attention. The concentrations of total PAHs in the floor soils (43.40-190 ng g -1, mean 87.76 ng g -1) were higher than those in the upper rim (23.40-88.94 ng g -1, mean 57.74 ng g -1). In addition, there was a shift in compound pattern with an increase in the proportion of light PAHs (2-3 rings), a decrease in heavy PAHs (5-6 rings) and a relatively stable content of 4-ring PAHs. A combination of particulate scavenging and cold condensation is proposed as the major mechanism for the compositional fractionation of PAHs in the soils from the upper rim and floor of tiankeng. © 2011 Springer-Verlag. Source

He S.-Y.,Chinese Academy of Geological Sciences | He S.-Y.,International Research Center on Karst | Kang Z.-Q.,Chinese Academy of Geological Sciences | Kang Z.-Q.,International Research Center on Karst | And 6 more authors.
Advances in Climate Change Research | Year: 2012

The karst process acts as carbon sequestration for atmospheric CO2. The amount of karst carbon sequestration (KCS) depends on the discharge of karst catchment and inorganic carbon concentration of the water body. Based on the data from the monitoring station on Banzhai subterranean stream located in Maolan National Nature Reserve of Guizhou province, the process and influence factors of KCS have been analyzed. It shows that the amount of KCS is about 353 t C per year in the catchment of Banzhai subterranean stream, and there is good linear relationship between the strength of KCS and discharge of the stream at various time scales. Therefore, how to monitor the discharge accurately is the key to the estimation of KCS. And stations with real-time monitoring function are very important for KCS calculation because of strong seasonal variability of the karst water cycle. Source

Wang R.-H.,Hubei University | Wang R.-H.,Guangxi General Institute of Geology and Exploration | Li M.,Guangxi General Institute of Geology and Exploration | Chen D.-X.,No. 6 Geological Exploration Party of Guangxi
Geological Bulletin of China | Year: 2011

According to characteristics of regional mineralization and typical ore deposits in Guangxi, the authors made a systematic summarization of features of lateritic high-iron gibbsite bauxite mineralization and a thorough analysis of the factors controlling this type of bauxite deposits. Comprehensive localization and quantitative prognosis of lateritic high-iron gibbsite bauxite deposits were carried out by using the GIS-based deposit model comprehensive geological information prediction method. 42 ore targets were delineated, and potential resources are estimated to be about 767 million tons. These results have important guiding significance for further prospecting and development of the lateritic high-iron gibbsite bauxite deposits. Source

Wang R.-H.,Hubei University | Wang R.-H.,Guangxi General Institute of Geology and Exploration | Li M.,Guangxi General Institute of Geology and Exploration | Meng Y.-J.,Guangxi Fourth Geologic Exploration Team
Geological Bulletin of China | Year: 2010

Based on existing study on regional metallogenic characteristics and typical deposits in Guangxi, we not only summaried systematically geology, geochemistry and remote sensing features of accumulative type bauxite mineralization in this area, but also deeply analyzed major ore-controlling factors. Thus, regional metallogenic model is set up. We've got comprehensive localization and quantitative estimation of accumulative type bauxite in Guangxi by GIS-based deposit modelling comprehensive geological information prediction method. The conclusion is as follows: 102 minimum tracts are given out, and potential resources amount to about 303 million tons, which has highly indicative significance for further ore-prospecting of this type. Source

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