Quantitative evaluation of soil erosion of land subsided by coal mining using RUSLE

Based on a RUSLE model, we identified the key factors of the impact on soil erosion induced by coal min- ing subsidence. We designed a method for predicting/.S factors of a mining subsidence basin, using ana- lytical GIS spatial technology. Using the Huainan mining area as an example, we calculated the modulus of erosion, its volume and classified the grade of soil erosion for both the original area and the subsidence basin. The results show that the maximum modulus of erosion and the volume of erosion of the subsi- dence basin without water logging would increase by 78% and 23% respectively compared with the ori- ginal situation. The edge of the subsidence basin, where the land subsidence was uneven, is subject to the greatest acceleration in soil erosion. In the situation of water logging after subsidence, the maximum modulus of erosion would decrease if the accumulated slope length were reduced. This maximum mod- ulus around the water logged area within the subsidence basin is equal to that without water logging, while the total volume of erosion decreases. Therefore, mining subsidence aggravates soil erosion espe- cially at the edge of basins where water and soil conservation measures should be taken.

Petrographic Evaluation of the Ranks and Technological Applications of Some Coal Deposits in the Anambra Basin and Middle Benue Trough of Nigeria

The coal resources of Nigeria occur mainly within the Benue Trough which includes the Anambra Basin. In the Lower Benue Trough/Anambra Basin, sub-bituminous coals occur within the Maastrichtian Mamu Formation in Enugu （Enugu State）, Owukpa （Benue State）, Okaba （Kogi State） and Ogboyaga （Kogi State）. High-volatile bituminous coals occur within the Turonian-Coniacian Awgu Formation in the Middle Benue Trough around Obi/Lafia （Nasarawa State） with outcrop exposures at Jangwa-Shankodi. Organic petrographic results show that huminites dominate the maceral composition of the Anambra Basin coals and have vitrinite reflectance values that range from 0.40% to 0.63 Ro%. In the coals from the Middle Benue Trough, vitrinite macerals predominate the petrographic composition and Ro values range from 0.81% to 1.25%. Based on the petrographic composition and rank evaluation, the sub-bituminous coals in Enugu, Owukpa, Okaba and Ogboyaga （Anambra Basin） are optimum for combustion and electric power generation and sub-optimum for liquefaction, while the high-volatile bituminous coals in the Obi/Lafia area （Middle Benue Trough）, apart from being optimum for liquefaction, are the most suitable as raw material for coke making （carbonization） in steel manufacture and as exploration targets for coal-bed methane gas and liquid hydrocarbons.

Preferential adsorption behaviour of CH_4 and CO_2 on high-rank coal from Qinshui Basin,China

In order to better understand the prevailing mechanism of CO2 storage in coal and estimate CO2 sequestration capacity of a coal seam and enhanced coalbed methane recovery （ECBM） with CO2 injection into coal, we investigated the preferential adsorption of CH4 and CO2 on coals. Adsorption of pure CO2, CH4 and their binary mixtures on high-rank coals from Qinshui Basin in China were employed to study the preferential adsorption behaviour. Multiple regression equations were presented to predict CH4 equi- librium concentration from equilibrium pressure and its initial-composition in feed gas. The results show that preferential adsorption of CO2 on coals over the entire pressure range under competitive sorption conditions was observed, however, preferential adsorption of CH4 over CO2 on low-volatile bituminous coal from higher CH4-compostion in source gas was found at up to 1O MPa pressure. Preferential adsorp- tion of CO2 increases with increase of CH4 concentration in source gas, and decreases with increasing pressure. Although there was no systematic investigation of the effect of coal rank on preferential adsorp- tion, there are obvious differences in preferential adsorption of gas between low-volatile bituminous coal and anthracite. The obtained preferential adsorption gives rise to the assumption that CO2 sequestration in coal beds with subsequent CO2-ECBM might be an ootion in Qinshui Basins, China.

Carboniferous–Permian marine transgressions in the Jiyang Depression

In recent years, great attention has been paid to oil and gas exploration in the Carboniferous-Permian strata of the Bohaiwan basin, especially the Carboniferous-Permian marine transgression, using data from drilling, outcrops and carbonate acid-insoluble residue experiments together with the tectonic evo- lutionary history of the peripheral orogenic zones of the North China plate and the Tan-Lu fault zones. The .＇;tudy concludes that marine transgressions took place on six occasions during Carboniferous-Perm- ian time in the Jiyang Depression. The marine transgressions were concentrated in the Late Carbonifer- ous： two marine transgressions occurred in the early Late Carboniferous, and the scale of the first was smaller and the time was shorter than those of the second. The other four marine transgressions hap- pened in the late Late Carboniferous, the first and the fourth of which were larger in scale and longer in time than the second and the third. The seawater came from the Jiaobei area, the eastward part of the Qinling-Dabie residual sea basin, and invaded progressively as a planar flow from south to north and from east to west. These findings have great significance for thorough analysis of the sedimentary characteristics and evolution of the Carboniferous-Permian strata in the livang Denression.

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Holocene peatland development and vegetation changes in the Zoige Basin, eastern Tibetan Plateau

Peat sediments and peatland evolution process offer abundant clues into the history of vegetation and climate changes.In order to reconstruct Holocene peatland, vegetation and climate changes on eastern Tibetan Plateau, we conducted analyses of fossil pollen, loss-on-ignition, and carbon accumulation rate on one peat core from Zoige Basin. Our results show local peatland initiated at 10.3 ka, thrived in the early-mid Holocene, and then began to degrade. Throughout the Holocene, Zoige Basin was dominated by alpine meadow. Coniferous forest on montane regions expanded for several times during 10.5–4.6ka, and then dramatically retreated. Results of peatland property, principal component analysis on fossil pollen suggested the climate maintained warm/wet during 10–5.5 ka, and became relatively cold/dry in the late Holocene. Rapid degradation of peatland, retreat of coniferous forest and climatic drought/cooling occurred at 10.2–10, 9.7–9.5, 8.7–8.5, 7.7–7.4, 6.4–6, 5.5–5.2,4.8–4.5, 4–3.6, 3.1–2.7, 1.4–1.2 and 0.8–0.6 ka. The long-term variations of Holocene climate and vegetation on eastern Tibetan Plateau could be attributed to changes in insolation-driven temperature and Asian Summer Monsoon intensity, while those rapid centennial changes were probably triggered by abrupt monsoon failures and temperature anomalies in the high northern latitudes.