Source of nutrient substrates for microbes in deep biosphere and characteristics of biogenic gas source rock

Abstract

To understand the biogas formation in geological basins, the present work investigated the reactive organic matter in sediments of the Sanhu depression of Qaidam Basin, a prolific region of biogenic gases with a proved reserve of 300 bil steres. The ROC (reactive organic carbon) was obtained by ultrasonic extraction from sediment samples in the solution of 6 mol/L HCl and 5% K 2 SO 4 . To investigate the effect of early diagenesis, parts of the samples were heated at 80°C before extraction. The results showed that the ROC content at a constant temperature decreased with increasing burial depths, which should be attributed to the microbial consumption. For the same sample, the ROC content heated at 80°C was dramatically higher than the unheated. The increment of the ROC content for some samples was as high as 200% in the experiment. The dramatically increasing ROC by thermal action should be the major nutrient substrate for the deep biospheres in most geological basins. There is a positive correlation between the reactive organic carbon (ROC) and the traditional insoluble organic carbon (TOC), not only for its absolute content of the ROC, but also for the 'ROC' produced in thermal action, all of these are clearly related with TOC. These data showed that higher abundance of organic matter can contribute more to the reactive organic matter, and is more favorable to the formation of biogenic gases. In the Sanhu depression of Qaidam Basin, more than 85% of the biogenic gas reserves occur in the lower layers (K5-K13) with a relatively high abundance of organic matter. The exploration has provided further evidence that deposits with higher abundance of organic matter are effective biogas source rocks. biogenic gases, gas source rock, Qaidam Basin, reactive organic matter, TOC Citation:Shuai Y H, Zhang S C, Chen J P, et al. Source of nutrient substrates for microbes in deep biosphere and characteristics of biogenic gas source rock.

A novel mode of chromosomal evolution peculiar to filamentous Ascomycete fungi

“…A number of reasons have been proposed to account for this. Filamentous fungi reflect approximately 400 million years of evolutionary history, comparable to that of the vertebrates but approximately four times longer than that of the flowering plants [13] (Figure 1; Table 1). The generation times of fungi are typically measured in hours or days, whereas plants and animals have generation times of many weeks, years or even decades.…”

12. Assessing biosphere-geosphere interactions over geologic time scales: insights from Basin Modeling

“…Newer investigations indicate that simply the presence of organic matter is not enough Brought to you by | Stockholms Universitet Authenticated Download Date | 8/25/15 7:03 AM for biogenic gas formation, but that the organic matter needs to be accessible to methanogens, i.e. it is necessary to differentiate between "reactive organic carbon" (ROC) as compared to the TOC [15]. In addition, neither in situ optimum growth conditions for deep biosphere methanogens, nor carbon turnover rates are known (i.e.…”

Potential and Constraints of Biogenic Methane Generation from Coals and Mudstones from Huaibei Coalfield, Eastern China

“…The biogenic methane was generated from various coals of different ranks. , The maximum methane yields of 83.7 m 3 /t and 10.8 m 3 /t occur from bituminous coal with a fed-batch scheme and from subbituminous coal incubated without hydrogen addition, respectively. ,, A preliminary investigation conducted on shale organic matter provided the evidence of biodegradation, such as losses of light aromatic hydrocarbons, short-chain (C 15 –C 19 ) n -alkanes, and acyclic isoprenoid alkanes in shale extracts. , However, to the authors’ knowledge, there is not any research on the biodegradation of mudstone (TOC content less than 6%) and carbonaceous mudstone (TOC content ranging from 6% to 40%). Mudstone and carbonaceous mudstone with a high content of organic matter were proven to be an effective biogenic gas source rock in the Sanhu depression of Qaidam basin. , The abundant organic matter can largely afford microbial sulfate reduction and reach the methanogenic process …”

“…Mudstone and carbonaceous mudstone with a high content of organic matter were proven to be an effective biogenic gas source rock in the Sanhu depression of Qaidam basin. 39,40 The abundant organic matter can largely afford microbial sulfate reduction and reach the methanogenic process. 40 The Huaibei−Huainan coalfield, located at the southeastern margin of the North China Plate, is one of the most important coal mining and CBM exploitation sites in eastern China.…”