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Previous studies on microbial prospecting of oil/gas only focused on the anomalies of light hydrocarbon-oxidizing microbes as main exploratory indicators and their exploration applications. In this study, we investigated the responses of microbial communities to light-hydrocarbon microseepage in the Beihanzhuang Oilfield, eastern China using denaturing gradient gel electrophoresis (DGGE) analysis and by comparing the difference of two-type areas with high- and low-flux light-hydrocarbon seepages. The results showed that the high-flux light-hydrocarbon seepage favored the growth ofNocardioides,Aciditerrimonas, sulphate-reducing bacteria (SRBs) related toDesulfosporosinusandDesulfovibrio, and Chloroflexi bacteria (b-7), implying that their anomalies might be adopted as novel subsidiary indicators for microbial prospecting of oil/gas in the Beihanzhuang Oilfield. Based on the newly obtained results, we have proposed a general strategy for microbial prospecting of oil/gas, i.e., to determine the anomalies of light hydrocarbon-oxidizing microbes, to select subsidiary indicators for microbial prospecting of oil/gas based on an assessment of the responses of microbial communities to light-hydrocarbon microseepage, to quantitatively measure subsidiary indicators and delimit their anomalies, to comprehensively interpret all microbial anomalies, and to make a suggestion for oil/gas prospecting. This general strategy with novel indicators may provide a more comprehensive evaluation for light-hydrocarbon microseepage and the corresponding anomalies, thereby reducing the exploration risk of oil/gas. [ABSTRACT FROM AUTHOR]

The vertical distributions of methane-oxidizing bacteria (MOBs) and sulfate-reducing bacteria (SRBs) in the marine sediment core of DH-CL14 from the Dongsha region, the South China Sea, were investigated. To enumerate MOBs and SRBs, their specific genes of pmoA and apsA were quantified by a culture-independent molecular biological technique, real-time polymerase chain reaction (RT-PCR). The result shows that the pmoA gene copies per gram of sediments reached the maximum of 1,118,679 at the depth of 140-160 cm. Overall considering the detection precision, sample amount, measurement cost, and sensitivity to the seepage of methane from the oil/gas reservoirs or gas hydrates, we suggest that the depth of 140-160 cm may be the optimal sampling position for the marine microbial exploration of oils, gases, and gas hydrates in the Dongsha region. The data of the pmoA and apsA gene copies exhibit an evident coupling relation between MOBs and SRBs as illustrated in their vertical distributions in this sediment core, which may well be interpreted by a high sulfate concentration inhibiting methane production and further leading to the reduction of MOBs. In comparison with the numbers of the pmoA and apsA copies at the same sediment depth, we find out that there were two methane-oxidizing mechanisms of aerobic and anaerobic oxidation in this sediment core, i.e., the aerobic oxidation with free oxygen dominantly occurred above the depth of 210-230 cm, while the anaerobic oxidation with the other electron acceptors such as sulfates and manganese-iron oxides happened below the depth of 210-230 cm.

Based on the 1961-2007 meteorological data of Haikou City and its urbanization level in 1989-2007, this paper studied the climatope change and its relations with city development of the City. In 1995-2007, the mean annual air temperature in Haikou had an obvious increase, with an increment of 0.93 degrees C x a(-1), while the mean annual relative humidity decreased obviously, with a decrement of 3% per year, compared with those in 1961-1990. Both the mean annual air temperature and the mean annual relative humidity had significant correlations with the urbanization level of Haikou, suggesting that urbanization could better explain the recent 20 years variation of climate elements in Haikou. The city development of Haikou not only changed the climatope elements, but also affected the air quality, making the frequency of acid rain increased, and the mean annual acid rain pH value decreased.