Journal of Natural Gas Chemistry is covered by Ei Compendex

We announce with pleasure that the Journal of Natural Gas Chemistry （JNGC） has been covered by Ei Compendex （Ei） since 2006. Now the first issue of Journal of Natural Gas Chemistry this year （in Vol. 15） is available on Ei compendex （http：//www.engineeringvillage2.org.cn）. At the same time, the full texts of JNGC in 2006 （Vol. 15, No. 1） are also available online on ScienceDirect （http：//www.sciencedirect.com/science/journal/10039953）. For more information, please visit the following website on Elsevier： http：//www.elsevier.com/locate/jngc.

Use of Evapotranspiration (ET) Landfill Covers to Reduce Methane Emissions from Municipal Solid Waste Landfills

Solid waste landfills need to have final covers to 1) reduce the infiltration of rainfall into the waste mass and 2) reduce surface greenhouse gas emissions. Most regulations require that such final covers include hydraulic barriers, such as compacted clays with or without geomembrane. Significant research has been undertaken to allow the use of evapotranspiration-based covers (often termed: Evapotranspiration (ET) Cover, Water Balance Covers, or Phyto Covers) as an alternative to the barrier concept covers. ET covers are designed so that they have the capacity to store water by the soil and also have plants or vegetation to remove the stored water. In ET covers, plant roots can enhance the aeration of soil by creating secondary macropores which improve the diffusion of oxygen into soil. Therefore, biological methane oxidation (a natural process in landfill soils) can be improved considerably by the soil structuring processes of vegetation, along with the increase of organic biomass in the soil associated with plant roots. This paper summarizes a study to investigate the capacity of an ET cover to reduce surface greenhouse gas emissions when implemented on a solid waste landfill. This study consisted of using a numerical model to estimate methane emission and oxidation through an ET cover under average climatic conditions in Bennignton, Nebraska, USA. Different simulations were performed using different methane loading flux (5 to 200 gm-2·d-1) as the bottom boundary. For all simulations, surface emissions were the lowest during the growing season and during warmer days of the year. Percent oxidation is the highest during the growing season and during warmer days. The lowest modeled surface emissions were always obtained during the growing season. Finally, correlations between percent oxidation and methane loading into simulated ET covers were proposed to estimate methane emissions and methane oxidation in ET covers.

Some Notes on the Key Botanical Territories of Ustyurt (Uzbekistan) and the Influence of Oil and Gas Industries on Them

The paper presents data on the modern state of some important botanical territories of the Ustyurt plateau. Materials on the effect of dust rising from the main highway of the oil and gas sector on the vegetation cover of the adjacent areas studied are considered. The results of the analysis showed that the vitality of dominants and rare species along the road and closer to it is low, the projective coverage does not exceed 8%. Starting from 100 to 200 m, the vitality of the dominants improves. With a distance of 500 m from the roads, the species composition increases, the projective coverage reaches 12%. The evaluation of the vitality of dominant and/or endemic species, the comparison of the projective cover and the species diversity of the pilot site with the control plot, and also the method of weighing the annual shoots of dominant and/or rare species with all vegetative and generative elements in a comparative aspect give reliable results in determining the degree Anthropogenic impact on the vegetation cover of Ustyurt. Inclusion of dominants the restoration of vegetation by phytoremediation of the study area gives promising results.

Hydrocarbon-Generating Model of the Area Covered With Volcanic Rock

The distribution of Oil & gas fields shows their close relationship with the most active tectonic regions. This is not a coincidence but having a scientific reasons. The crustal active regions, refer to the places where the active natural earthquake, volcanic activities, underground water happened, and the areas of the leaking Off of natural gas to the surface of the crust. The magma of volcanic activities brings the organic "kitchen range body" hydrocarbon - generating model and inorganic genetic hydrocarbon to the regions covered by volcanic rock. Underground water brings a catalytic hydrocarbon generating model for organic matter, and the leaking - off of H2 and CO2 contributes a synthetic hydrocarbon - generating model. Volcanic activities bring the assemblage of Source, Reservoir and Seal formed by the sediments and magma the sedimentary basins, and the hydrocarbon - generating system with a "water - volcano" binary structure is formed. All these conditions are favorable and excellent for the formation of oil & gas fields. The distribution of AInerican oil & gas fields have very close relationship with the mines of Fe, Mn, Cr, Mo, W and V, deposits of Zn, Cu, V, Pb, Al and Hg, and the deposits of fluorite, sulfur, potassium salt, phosphate and halite, and the distribution of sulfate - chloride of river water. The reason why few oil & gas fields discovered in the regions covered by volcanic rock in western America maybe because of the view of "inconsistency between petroleum and volcano". Further more, It’s very difficult to carry out a geophysical exploration in such kinds of regions. This paper examined a few hydrocarbon - generating models (systems) mentioned above and came up with some flesh ideas on the exploration in the areas covered with volcanic rocks.

NUMERICAL CALCULATION OF DILUTE GAS-PARTICLE FLOWS IN A CYLINDRICAL CONTAINER WITH A ROTATING COVER

A new computing technique is described for the solution'of dilute gas-particle fluid flow problems.The com- mon SIMPLE method is used for the calculation of the gas phase,but for the calculation of the particle phase the MacCormack method(80 style)is used.Using the technique for gas-particle flows in a rotating cylindrical con- tainer,the field distributions of both phases are obtained.An important parameter Sk(Stokes number)is taken re- spectively as 0.01,0.1 and 1.The results show the influence of Sk on the flows.The collisions between particles and the side wall of the container are predicted when Sk=1.

Methane oxidation and attenuation of sulphur compounds in landfill top cover systems: Lab-scale tests

In this study,a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable.Different materials were studied as landfill cover system in lab-scale columns：mechanical–biological pretreated municipal solid waste（MBP）;mechanical–biological pretreated biowaste（PB）;fine（PBSf）and coarse（PBSc）mechanical–biological pretreated mixtures of biowaste and sewage sludge,and natural soil（NS）.The effectiveness of these materials in removing methane and sulphur compounds from a gas stream was tested,even coupled with activated carbon membranes.Concentrations of CO2,CH4,O2,N2,H2S and mercaptans were analysed at different depths along the columns.Methane degradation was assessed using mass balance and the results were expressed in terms of methane oxidation rate（MOR）.The highest maximum and mean MOR were observed for MBP（17.2 g CH4/m^2/hr and 10.3 g CH4/m^2/hr,respectively）.Similar values were obtained with PB and PBSc.The lowest values of MOR were obtained for NS（6.7 g CH4/m^2/hr）and PBSf（3.6 g CH4/m^2/hr）,which may be due to their low organic content and void index,respectively.Activated membranes with high load capacity did not seem to have an influence on the methane oxidation process：MBP coupled with 220 g/m^2and 360 g/m^2membranes gave maximum MOR of 16.5 g CH4/m^2/hr and 17.4 g CH4/m^2/hr,respectively.Activated carbon membranes proved to be very effective on H2S adsorption.Furthermore,carbonyl sulphide,ethyl mercaptan and isopropyl mercaptan seemed to be easily absorbed by the filling materials.

In-situ neutralize methane emission from landfills in loess regions using leachate

In loess regions, landfilling is the predominant solid waste disposal and loess is usually used as landfill cover soil. However, the methane(CH_4) bio-oxidation activity of virgin loess is usually below 0.01 μmol/(h g-soil). In this study, we proposed a method to improve CH_4 removal capacity of loess by amelioration with mature landfill leachate, which is in-situ, easily available, and appropriate. The organic matter content of the ameliorated loess increased by 180%, reaching 19.69–24.88 g/kg-soil, with more than 90% being non-leachable. The abundance of type I methane-oxidizing bacteria and methane monooxygenase gene pmoA increased by 5.0 and 79 times, respectively. Consequently, the maximum CH_4 removal rate of ameliorated loess reached 0.74–1.41 μmol/(h g-soil) at 25°C, which was 4-fold higher than that of water-irrigated loess. Besides, the CH_4 removal rate peaked at 10 vt% CH_4 concentration and remained at around 1.4 μmol/(h g-soil) at 15°C–35°C. The column test confirmed that the highest CH_4 removal efficiency was at 30–40 cm below the surface, reaching 26.1%±0.4%, and the 50-cm-thick loess layer irrigated with leachate achieved more than 85% CH_4 removal efficiency. These results could help to realize carbon neutrality in landfill sites of global loess regions.