Evaluation of coal bed methane potential of coal seams of Sawang Colliery,Jharkhand, India     

Anil M. Pophare  Vinod A. Mendhe  A. Varade 《Journal of Earth System Science》2008,117(2):121-132

The coal seams of Sawang Colliery, East Bokaro Coalfields are bituminous to sub-bituminous in nature and categorized as high gaseous seams (degree II to degree III level). These seams have the potential for coal bed methane (CBM) and their maturity increases with increasing depth, as a result of enhanced pressure-temperature conditions in the underground. The vitrinite maceral group composition of the investigated coal seams ranges from 62.50–83.15%, whereas the inertinite content varies from 14.93–36.81%. The liptinite content varies from 0.66% to 3.09%. The maximum micro-pores are confined within the vitrinite group of macerals. The coal seams exhibit vitrinite reflectance values (Ro% calculated) from 0.94% (sample CG-97) to 1.21% (sample CG-119). Proximate analyses of the investigated coal samples reveal that the moisture content (M%) ranges from 1.28% to 2.98%, whereas, volatile matter (VM%) content is placed in the range of 27.01% to 33.86%. The ash content (A%) ranges from 10.92% to 30.01%. Fixed carbon (FC%) content varies from 41.53% to 55.93%. Fuel ratio variation shows a restricted range from 1.53 to 1.97. All the coal samples were found to be strongly caking and forming coke buttons. The present study is based on the adsorption isotherm experiments carried out under controlled P-T conditions for determination of actual gas adsorption capacity of the coal seams. This analysis shows that the maximum methane gas adsorbed in the coal sample CG-81 is 17 m³/t (Std. daf), at maximum pressure of 5.92 MPa and experimental temperature of 30°C. The calculated Langmuir regression parameters P_L and V_L range from 2.49 to 3.75 MPa and 22.94 to 26.88 m³/t (Std. daf), respectively.  相似文献   

Comments on ‘A comparative study of ANN and neuro-fuzzy for the prediction of dynamic constant of rockmass’     

Tarkan Erdik  Zekai Şen 《Journal of Earth System Science》2008,117(6):973-974

Singh et al (2005) examined the potential of the ANN and neuro-fuzzy systems application for the prediction of dynamic constant of rockmass. However, the model proposed by them has some drawbacks according to fuzzy logic principles. This discussion will focus on the main fuzzy logic principles which authors and potential readers should take into consideration.  相似文献   

Proposed seismic hazard maps of Sumatra and Java islands and microzonation study of Jakarta city,Indonesia     

Masyhur Irsyam  Donny T. Dangkua  Hendriyawan  Drajat Hoedajanto  Bigman M. Hutapea  Engkon K. Kertapati  Teddy Boen  Mark D. Petersen 《Journal of Earth System Science》2008,117(2):865-878

This paper presents the development of spectral hazard maps for Sumatra and Java islands, Indonesia and microzonation study for Jakarta city. The purpose of this study is to propose a revision of the seismic hazard map in Indonesian Seismic Code SNI 03-1726-2002. Some improvements in seismic hazard analysis were implemented in the analysis by considering the recent seismic activities around Java and Sumatra. The seismic hazard analysis was carried out using 3-dimension (3-D) seismic source models (fault source model) using the latest research works regarding the tectonic setting of Sumatra and Java. Two hazard levels were analysed for representing 10% and 2% probability of exceedance (PE) in 50 years ground motions for Sumatra and Java. Peak ground acceleration contour maps for those two hazard levels and two additional macrozonation maps for 10% PE in 50 years were produced during this research. These two additional maps represent short period (0.2 s) and long-period (1.0 s) spectra values at the bedrock. Microzonation study is performed in order to obtain ground motion parameters such as acceleration, amplification factor and response spectra at the surface of Jakarta. The analyses were carried out using nonlinear approach. The results were used to develop contour of acceleration at the surface of Jakarta. Finally, the design response spectra for structural design purposes are proposed in this study.  相似文献   

He–Ar and Nd–Sr isotopic compositions of late Pleistocene felsic plutonic back arc basin rocks from Ulleungdo volcanic island, South Korea: Implications for the genesis of young plutonic rocks in a back arc basin     

Kyu Han Kim  Keisuke Nagao  Hirochika Sumino  Tsuyoshi Tanaka  Takamasa Hayashi  Toshio Nakamura  Jong Ik Lee 《Chemical Geology》2008,253(3-4):180-195

We report analyses of noble gases and Nd–Sr isotopes in mineral separates and whole rocks of late Pleistocene (< 0.2 Ma) monzonites from Ulleungdo, South Korea, a volcanic island within the back arc basin of the Japan island arc. A Rb–Sr mineral isochron age for the monzonites is 0.12 ± 0.01 Ma. K–Ar biotite ages from the same samples gave relatively concordant ages of 0.19 ± 0.01and 0.22 ± 0.01 Ma. ⁴⁰Ar/³⁹Ar yields a similar age of 0.29 ± 0.09 Ma. Geochemical characteristics of the felsic plutonic rocks, which are silica oversaturated alkali felsic rocks (av., 12.5 wt% in K₂O + Na₂O), are similar to those of 30 alkali volcanics from Ulleungdo in terms of concentrations of major, trace and REE elements. The initial Nd–Sr isotopic ratios of the monzonites (⁸⁷Sr/⁸⁶Sr = 0.70454–0.71264, ¹⁴³Nd/¹⁴⁴Nd = 0.512528–0.512577) are comparable with those of the alkali volcanics (⁸⁷Sr/⁸⁶Sr = 0.70466–0.70892, ¹⁴³Nd/¹⁴⁴Nd = 0.512521–0.512615) erupted in Stage 3 of Ulleungdo volcanism (0.24–0.47 Ma). The high initial ⁸⁷Sr/⁸⁶Sr values of the monzonites imply that seawater and crustally contaminated pre-existing trachytes may have been melted or assimilated during differentiation of the alkali basaltic magma.A mantle helium component (³He/⁴He ratio of up to 6.5 RA) associated with excess argon was found in the monzonites. Feldspar and biotite have preferentially lost helium during slow cooling at depth and/or during their transportation to the surface in a hot host magma. The source magma noble gas isotopic features are well preserved in fluid inclusions in hornblende, and indicate that the magma may be directly derived from subcontinental lithospheric mantle metasomatized by an ancient subduction process, or may have formed as a mixture of MORB-like mantle and crustal components. The radiometric ages, geochemical and Nd–Sr isotopic signatures of the Ulleungdo monzonites as well as the presence of mantle-derived helium and argon, suggests that these felsic plutonic rocks evolved from alkali basaltic magma that formed by partial melting of subcontinental lithospheric mantle beneath the back arc basin located along the active continental margin of the southeastern part of the Eurasian plate.  相似文献   

Chemical weathering of carbonates and silicates in the Han River basin,South Korea     

Jong-Sik Ryu  Kwang-Sik Lee  Ho-Wan Chang  Hyung Seon Shin 《Chemical Geology》2008,247(1-2):66-80

A detailed investigation of the fluvial geochemistry of the Han River system allows to estimate the rates of chemical weathering and the consumption of CO₂. The Han River drains approximately 26,000 km² and is the largest river system in South Korea in terms of both water discharge and total river length. It consists of two major tributaries: the North Han River (NHR) and the South Han River (SHR). Distinct differences in basin lithology (silicate vs. carbonate) between the NHR and SHR provide a good natural laboratory in which to examine weathering processes and the influence of basin geology on water quality. The concentrations of major elements and the Sr isotopic compositions were obtained from 58 samples collected in both summer and winter along the Han River system in both 2000 and 2006. The concentrations of dissolved loads differed considerably between the NHR and SHR; compared with the SHR, the NHR had much lower total dissolved solids (TDS), Sr, and major ion concentrations but a higher Si concentration and ⁸⁷Sr/⁸⁶Sr ratio. A forward model showed that the dissolved loads in the NHR came primarily from silicate weathering (55 ± 11%), with a relatively small portion from carbonates (30 ± 14%), whereas the main contribution to the dissolved loads in the SHR was carbonate weathering (82 ± 3%), with only 11 ± 4% from silicates. These results are consistent with the different lithologies of the two drainage basins: silicate rocks in the NHR versus carbonate rocks in the SHR. Sulfuric acid derived from sulfide dissolution in coal-containing sedimentary strata has played an important role in carbonate weathering in the SHR basin, unlike in the NHR basin. The silicate weathering rate (SWR) was similar between the NHR and SHR basins, but the rate of CO₂ consumption in the SHR basin was lower than in the NHR basin due to an important role of sulfuric acid derived from pyrite oxidation.  相似文献   

Using ALSM to map sinkholes in the urbanized covered karst of Pinellas County,Florida—1, methodological considerations   总被引：1，自引：0，他引：1  

Larry D. Seale  Lee J. Florea  H. L. Vacher  Robert Brinkmann 《Environmental Geology》2008,54(5):995-1005

Comparison of a database of interpreted sinkholes made using airborne laser swath mapping (ALSM) with databases of sinkholes made from interpretation of aerial photographs reveals substantial disagreement. The discrepancies involve the location, number, areas, and circularity of interpreted sinkholes. Methodological factors that contribute to the discrepancies include blockage of ALSM laser returns in thick vegetation, multi-path reflections, and misrepresentation of the true extent of sinkholes. Comparison of two ALSM-derived databases made (1) independently from versus (2) in combination with earlier air photo analysis in undeveloped regions had the following result: one-fourth of the sinkholes interpreted by using the composite method were missed by the independent analysis, and one-third of the sinkholes that were interpreted from the independent analysis were not interpreted as sinkholes using the composite method. Subjective interpretation leads to a high level of uncertainty such that the results of the remote sensing studies are suspect, if not invalid.  相似文献   

Hydrochemical characteristics and the effects of irrigation on groundwater quality in Harran Plain,GAP Project,Turkey     

M. Irfan Yesilnacar  M. Said Gulluoglu 《Environmental Geology》2008,54(1):183-196

Improper design, faulty planning, mismanagement and incorrect operation of irrigation schemes are the principle reasons for the deterioration of groundwater quality in a large number of countries, in particular in semi-arid and arid regions. The aim of this study is to determine the dimensions of groundwater quality after surface irrigation was begun in the semi-arid Harran Plain. Physical and chemical parameters of the groundwater including pH, temperature, electrical conductivity (EC), sodium, potassium, calcium, magnesium, chloride, bicarbonate, sulphate, nitrate, nitrite, ammonium, total phosphorus, total organic carbon and turbidity were determined monthly during the 2006 water year. The quality of the groundwater in the study area was assessed hydrochemically in order to determine its suitability for human consumption and agricultural purposes. In the general plain, the EC values measured were considerably above the guide level of 650 μS/cm, while nitrate in particular was found in almost all groundwater samples to be significantly above the maximum admissible concentration of 50 mg/l for the quality of water intended for human consumption as per the international and national standards. Total hardness reveals that a majority of the groundwater samples fall in the very hard water category. Interpretation of analytical data shows that Ca–HCO₃ and Ca–SO₄ are the dominant hydrochemical facies in the study area.  相似文献   

Delineation of groundwater protection zones by the backward particle tracking method: theoretical background and GIS-based stochastic analysis   总被引：1，自引：0，他引：1  

Konstadinos N. Moutsopoulos  Alexandra Gemitzi  Vassilios A. Tsihrintzis 《Environmental Geology》2008,54(5):1081-1090

The backward particle tracking method, an effective and powerful tool that can be used to delineate groundwater protection zones, is presented. The theoretical background and insights on the applicability of this method are provided. Moreover, the present work enriches the backward particle tracking method with an uncertainty analysis concerning the porosity values, applying a Monte Carlo (MC) approach, coupled with the use of geographical information systems (GIS). As an application example, a wellfield in the Komotini area, Greece, is investigated. The present study may serve as a potential guideline for wellfield delineation, particularly in areas like Greece where lack of data related to the hydrogeological system is often a problem.  相似文献   

Upcoming international events     

Anne Marie de Grosbois 《Environmental Geology》2008,54(5):1121-1126

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Case history of controlling a landslide at Panluo open-pit mine in China     

Zuoan Wei  Guangzhi Yin  Ling Wan  Louyan Shen 《Environmental Geology》2008,54(4):699-709

Controlling of landsides safely and economically is a great challenge to mine operators because landslides are major geological problems especially in open-pit mines. In this paper, a case history at Panluo open-pit mine is presented in detail to share the experiences and lessons with mine operators. Panluo open-pit mine is located in the southwestern Fujian province of China. It is the largest open-pit iron mine in the Fujian province and was planned in 1965 and is in full operation from 1978. In July 1990, an earthquake of magnitude 5.3 in Taiwan Strait and big rainstorms impacted the mine slope, causing tension cracks and rather large-scale failures, and forming a U-shaped landslide. Total potential volume was estimated to be up to 1.0 × 10⁶ m³. This directly threatened the mine production. In order to protect the mine production and the dwellers’ safety around, a dynamic comprehensive method was implemented including geotechnical investigations, in-situ testing and monitoring, stability analysis, and many mitigation and preventive measures. These measures slowed down the development and further occurrence of the landslide. The results showed that the landslides were still active, it was slowed with the control measures and moved rapidly with rainfall and mining down. However, no catastrophic accidents occurred and the pit mining was continued till it was closed at the elevation of 887 m in 2000. As a successful case of landslide control at an open-pit mine for 10 years, this paper reports the controlling measures in details. These experiences of landslide control may be beneficial to other similar mines for landslide control.  相似文献