• Asian Journal of Atmospheric Environment
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• v.8 no.1
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• pp.1-14
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• 2014

Migration of methane ($CH_4$) gas from landfills to the surrounding environment negatively affects both humankind and the environment. It is therefore essential to develop management techniques to reduce $CH_4$ emissions from landfills to minimize global warming and to reduce the human risks associated with $CH_4$ gas migration. Oxidation of $CH_4$ in landfill cover soil is the most important strategy for $CH_4$ emissions mitigation. $CH_4$ oxidation occurs naturally in landfill cover soils due to the abundance of methanotrophic bacteria. However, the activities of these bacteria are influenced by several controlling factors. This study attempts to review the important issues associated with the $CH_4$ oxidation process in landfill cover soils. The $CH_4$ oxidation process is highly sensitive to environmental factors and cover soil properties. The comparison of various biotic system techniques indicated that each technique has unique advantages and disadvantages, and the choice of the best technique for a specific application depends on economic constraints, treatment efficiency and landfill operations.

• Economic and Environmental Geology
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• v.34 no.3
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• pp.283-299
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• 2001

The middle cover soils and clay liners collected from the Kumheung landfill in Gongiu City were analysed for As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Ti and Zn concentrations using 0.] N HCl digestion and total/sequential extraction experiments followed by ICP-AES determination. The uncontaminated soil and sediment samples were also analyzed for the comparison. The results of sequential extraction showed that Cu was dominant in the oxidizable fraction, and As, Ni, Sr, Ba, and Mn were in the exchangeable fraction. Zinc and Mn occurred mostly in association with reducible, residual and carbonate fractions. Most of Cd and Pb were bound to the reducible and oxidizable fractions. The main carrier of Co, Cr, Fe and 11 was the residual fraction and another important carrier was the reducible fraction. The percentage of the metals of organically-bound form in the middle cover soils and clay liner was in the order of Cu(48%) > Ti(42%) > Pb(27%) > As(25%) > Cd(20%). As deduced from sequential extraction analysis, potential order of metal mobility in the middle cover soils and clay liner from the landfill was proposed: Cd > Sr > As > Ni > Mn > Ba > Cu > Pb > Zn » Co > 11 > Fe > Cr. Based on the 'geoaccumulation index' and the 'enrichment factor' normalized to A], the level of contamination of Cu, Ni and C1' was significant in the samples from Kumheung landfill and surrounding farmland. Their enrichments were attributed partly to anthropogenic pollutions.

• Journal of Forest and Environmental Science
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• v.38 no.1
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• pp.21-37
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• 2022

The present study was carried out to evaluate the chemical properties of soil in relation to forest structure and composition at different altitudes (900-2,600 m asl) in a part of Western Himalaya. The composite soil samples were taken from three (viz. upper, middle and lower) depths. The soils of the whole study area were acidic in nature (pH=4.90-5.51). Contents of Nitrogen (N), Phosphorus (P), Potassium (K), Carbon (C) and soil organic matter (SOM) showed much fluctuation during different seasons of year. Nitrogen content showed significant positive correlations with altitude (r=0.924, p<0.05) and different community parameters like species diversity (r=0.892, p<0.01) and species richness (r=0.941, p<0.05). Phosphorus exhibited direct correlations with carbon (r=0.637) while weak negative correlations with different community parameters like species richness & diversity, total basal cover (TBC), density and canopy cover. Carbon content and hence SOM showed direct correlations with Nitrogen (r=0.821, p<0.01); Phosphorus (r=0.637, ns) and Potassium (r=0.540, ns). But no significant relationship was observed between K content and species richness (p=0.30, r=-0.504); between K content and species diversity (p=0.14, r=-0.672); between P content and species diversity (p=0.29, r=-0.513) and species richness (p=0.23, r=-0.575). Among the different soil nutrients, only N showed a significant positive correlation with altitude while all others exhibited negative (but non-significant) correlation with it. The study revealed that the chemical properties affect and are reciprocally affected by forest structure and composition and that N rich soils of higher altitudes are best for the growth and development of forests.

• Journal of Forest and Environmental Science
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• v.26 no.2
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• pp.117-129
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• 2010

The present study was undertaken in moist temperate forest of Mandal-Chopta area in the Garhwal region of Uttarakhand, India. The aim of the present study was to assess the physical properties of soils in relation to the forest structure and composition. Twelve forest types according to the altitude, slope aspect and species compositions were selected for the study. Physical properties of soil i.e., soil colour, soil texture (per cent of sand, silt and clay), moisture content, water holding capacity, porosity, bulk density (gm/$cm^3$) and void ratio were analyzed for three different depths viz., (i) 'upper' (0-10 cm), (ii) 'middle' (11-30 cm) and (iii) 'lower' (31-60 cm) in all the selected forest types. Phytosociological and diversity parameters viz. total basal cover ($Gha^{-1}$), stem density ($Nha^{-1}$), tree species richness, Simpson concentration of dominance and Shannon-Wiener diversity index were also calculated for each forest type. This study also provides the comparisons between the results of physical analysis of the present study with numerous other previous studies in the temperate Himalayan region of the Uttarakhand.

• Korean Journal of Environmental Agriculture
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• v.26 no.4
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• pp.279-285
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• 2007

Soil physical properties in organic farming apple orchard were evaluated in relation to conventional farming to better understand the effects of organic farming system on soil quality. Two adjacent apple orchards, matched by soil type, were chosen to ensure the same pedological conditions except management system. Soil samples were collected from middle of two adjacent trees along the tree line at two depths of 5-20 and 20-35 cm in September 2006. Contents of organic matter in organic farming soil were twice as much as those found in soil of conventional farming. The higher level of organic matter in organic farming soil was reflected through a consequent trend in improved soil physical properties. Organic farming produced greater aggregation in >2 mm size and increased aggregate stability. Bulk density was lower by 13% and hence porosity was higher in soils of organic farming as compared with conventional farming. Water holding capacity was significantly greater with organic farming by >17% over conventional farming. The capacity of organic farming to improve soil physical properties can be contributed to the regular application of relatively large amount of organic materials and the sustainable ground-cover managements, mulching with compost and cover crop cultivation.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.179-189
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• 2000

The purpose of this research is to complement the existing researches on landfill bottom liners behavior during the periods of freeze and thaw. Landfill-related researches have been typically focused on small-scale soil samples that are often compacted under conditions different from those used in the field. Although these tests have been invaluable in clarifying the problem of freeze and thaw, extending the results of such experimental studies to prototype landfills are questionable. In this investigation, the author utilized a large scale laboratory simulation allowing inclusion of the field depth of the cover systems, layered soil profiles, rainfall simulation, a cold climate and boundary conditions similar to those encountered in the landfill. The soil materials were stabilized soils (mixed clays, cements, and minerals) instead of clays. The bottom liners are made up of drainage layer (30 cm), stabilized layer (75 cm), and leach collection layer (60 cm). The stabilized layers are made up of supporting layer (45 cm) and low permeable layer (30 cm) - consisting of $P_A\; and\; P_B$ layer. As a results, depths of penetration increased by about 2~5 more centimeters at rainfall simulated designs than those at no rainfall simulated designs (that is design 3, design 5 and design 7) - it increased by about 20mm/day in the bottom liners and frost heaves also increased it by a few millimeters. Also, a few cracks appeared partly. According to these results, we can surmise that the compacted stabilized soil is more reliable than the compacted clay liners for construction of the landfill liners.