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1

Methane Oxidation in Landfill Cover Soil  

Microsoft Academic Search

Methane oxidation in the cover soil of the Khmet'evo municipal landfill in Moscow oblast was investigated. Methane emission from the experimental site of the landfill was highly heterogeneous. At a depth of 45–60 cm, the pore gas mainly consisted of CH4 (60–70%) and CO2 (30–40%). In the upper layers of the cover soil, the concentration of these gases sharply decreased.

A. Yu. Kallistova; M. V. Kevbrina; V. K. Nekrasova; M. V. Glagolev; M. I. Serebryanaya; A. N. Nozhevnikova

2005-01-01

2

Vegetative soil covers for hazardous waste landfills  

NASA Astrophysics Data System (ADS)

Shallow land burial has been the preferred method for disposing of municipal and hazardous wastes in the United States because it is the simplest, cheapest, and most cost-effective method of disposal. Arid and semiarid regions of the western United States have received considerable attention over the past two decades in reference to hazardous, radioactive, and mixed waste disposal. Disposal is based upon the premise that low mean annual precipitation, high evapotranspiration, and low or negligible recharge, favor waste isolation from the environment for long periods of time. The objective of this study is to demonstrate that containment of municipal and hazardous wastes in arid and semiarid environments can be accomplished effectively without traditional, synthetic materials and complex, multi-layer systems. This research demonstrates that closure covers utilizing natural soils and native vegetation i.e., vegetative soil covers, will meet the technical equivalency criteria prescribed by the U.S. Environmental Protection Agency for hazardous waste landfills. Vegetative soil cover design combines layers of natural soil, native plant species, and climatic conditions to form a sustainable, functioning ecosystem that maintains the natural water balance. In this study, percolation through a natural analogue and an engineered cover is simulated using the one-dimensional, numerical code UNSAT-H. UNSAT-H is a Richards' equation-based model that simulates soil water infiltration, unsaturated flow, redistribution, evaporation, plant transpiration, and deep percolation. This study incorporates conservative, site-specific soil hydraulic and vegetation parameters. Historical meteorological data from 1919 to 1996 are used to simulate percolation through the natural analogue and an engineered cover, with and without vegetation. This study indicates that a 1 m (3 ft) cover is the minimum design thickness necessary to meet the U.S. Environmental Protection Agency-prescribed technical equivalency criteria of 31.5 mm/year and 1 x 10-7 cm/second for net annual percolation and average flux, respectively. Increasing cover thickness to 1.2 m (4 ft) or 1.5 m (5 ft) results in limited additional improvement in cover performance. Under historical climatic conditions, net annual percolation and average flux through a 1 m (3 ft) cover is directed upward at 0.28 mm/year and 9.03 x 10-10 cm/second, respectively, for a soil cover with vegetation.

Peace, Jerry L.

3

Methane oxidation in simulated landfill cover soil environments  

Microsoft Academic Search

Methane is an important greenhouse gas. Its contribution to the enhanced global warming is estimated at 12%. A considerable fraction of the methane that is produced by landfills is oxidized by its covering soil before it can reach the atmosphere. This process was studied in soil columns that simulate landfill cover soil environments. The methane uptake was followed as a

Alex De Visscher; Dirk Thomas; Pascal Boeckx; Oswald Van Cleemput

1999-01-01

4

[Research progress on methane oxidation in landfill cover soil].  

PubMed

Methane is the second largest contributor after carbon dioxide to global warming, while landfill is considered as one of the major sources of methane emission, accounting for 1.5%-15% of the global methane sources. Methanotrophic microorganisms play an important role in regulating global methane content, and landfill cover soil is proved to have high capacity of methane oxidation. The study of methanotrophic microorganisms in landfill cover soil and their mechanisms in methane oxidation becomes one of the hot research fields in environmental science and applied microbiology. This review summarized the recent progress on the research of methanotrophic microorganisms, mechanisms and dynamics of microbial methane oxidation, co-metabolism of methane and trace landfill gases, and environmental factors affecting methane oxidation in landfill cover soil. Some perspectives for further research on methanotrophic microorganisms in landfill cover soil were discussed. PMID:17396524

Wang, Yun-long; Hao, Yong-jun; Wu, Wei-xiang; Chen, Ying-xu

2007-01-01

5

Exopolysaccharide control of methane oxidation in landfill cover soil  

Microsoft Academic Search

The study objective was to examine whether a relationship exists between the accumulation of exopolymeric substances (EPS) in landfill cover soil and the gradual decline in biotic methane oxidation observed in laboratory soil columns sparged with synthetic landfill gas. A mathematical model that combined multicomponent gas diffusion along the vertical axis of the columns with biotic methane oxidation was used

Helene A. Hilger; Sarah K. Liehr; Morton A. Barlaz

1999-01-01

6

Methane oxidation and microbial exopolymer production in landfill cover soil  

Microsoft Academic Search

In laboratory simulations of methane oxidation in landfill cover soil, methane consumption consistently increased to a peak value and then declined to a lower steady-state value. It was hypothesized that a gradual accumulation of exopolymeric substances (EPS) contributed to decreased methane uptake by clogging soil pores or limiting gas diffusion. This study was conducted to detect and quantify EPS in

Helene A Hilger; David F Cranford; Morton A Barlaz

2000-01-01

7

Methane oxidation in simulated landfill cover soil environments  

SciTech Connect

Methane is an important greenhouse gas. Its contribution to the enhanced global warming is estimated at 12%. A considerable fraction of the methane that is produced by landfills is oxidized by its covering soil before it can reach the atmosphere. This process was studied in soil columns that simulate landfill cover soil environments. The methane uptake was followed as a function of time. In soils of agricultural origin, a maximum value of 10.7 mol m{sup {minus}2}{sub column} d{sup {minus}1} was observed. Mixing sugar beet leaves with the soil led to a temporary stimulation of the methane oxidation rate, whereas a wheat straw amendment led to permanent stimulation. Soil originating from a real landfill cover oxidized on the order of 15 mol m{sup {minus}2}{sub column} d{sup {minus}1}, the highest value found in the literature to date. The soil gas composition was studied as a function of depth. With a new batch incubation technique, methane oxidation kinetics were determined in samples taken from the soil column. By combining this kinetic data with the soil gas composition data, the actively methane oxidizing zone in the soil column could be determined and an in situ assessment of oxygen limitation could be performed. Methane oxidation takes place mainly in the top 30 cm of the covering soil.

Visscher, A. de; Thomas, D.; Boeckx, P.; Cleemput, O. van [Univ. of Ghent (Belgium)] [Univ. of Ghent (Belgium)

1999-06-01

8

Diversity and activity of methanotrophs in landfill cover soils with and without landfill gas recovery systems.  

PubMed

Aerobic CH4 oxidation plays an important role in mitigating CH4 release from landfills to the atmosphere. Therefore, in this study, oxidation activity and community of methanotrophs were investigated in a subtropical landfill. Among the three sites investigated, the highest CH4 concentration was detected in the landfill cover soil of the site (A) without a landfill gas (LFG) recovery system, although the refuse in the site had been deposited for a longer time (?14-15 years) compared to the other two sites (?6-11 years) where a LFG recovery system was applied. In April and September, the higher CH4 flux was detected in site A with 72.4 and 51.7gm(-2)d(-1), respectively, compared to the other sites. The abundance of methanotrophs assessed by quantification of pmoA varied with location and season. A linear relationship was observed between the abundance of methanotrophs and CH4 concentrations in the landfill cover soils (R=0.827, P<0.001). The key factors influencing the methanotrophic diversity in the landfill cover soils were pH, the water content and the CH4 concentration in the soil, of which pH was the most important factor. Type I methanotrophs, including Methylococcus, Methylosarcina, Methylomicrobium and Methylobacter, and type II methanotrophs (Methylocystis) were all detected in the landfill cover soils, with Methylocystis and Methylosarcina being the dominant genera. Methylocystis was abundant in the slightly acidic landfill cover soil, especially in September, and represented more than 89% of the total terminal-restriction fragment abundance. These findings indicated that the LFG recovery system, as well as physical and chemical parameters, affected the diversity and activity of methanotrophs in landfill cover soils. PMID:24332193

Su, Yao; Zhang, Xuan; Xia, Fang-Fang; Zhang, Qi-Qi; Kong, Jiao-Yan; Wang, Jing; He, Ruo

2014-05-01

9

Fines migration from soil daily covers in Hong Kong landfills.  

PubMed

Laboratory tests using 240 mm diameter columns were conducted to study fines migration in conditions that simulate daily soil covers in Hong Kong municipal solid waste landfills. Five factors suspected to affect fines migration were examined: moisture content at soil compaction, overburden pressure, pumping rate, cover thickness, and soil-waste interface condition. The results show that moisture content at compaction, cover thickness, and soil-waste interface are the most influential parameters on fines migration in completely decomposed granite daily covers. The measured equivalent sizes of migratory fines from the soil covers were in the range of 4-140 ?m. The majority of migratory fines migrated during first permeations, representing 64-86% of the total by mass. Larger particles tended to migrate from the soil mass during the saturation process. In a typical run, about 0.0018% of the total cover soil (by dry weight) was washed out during a typical 1h rainfall event. The results of the laboratory studies point to important engineering implications on the operation of local MSW landfills regarding the use of sandy daily covers. PMID:20359879

Ng, Kelvin T W; Lo, Irene M C

2010-11-01

10

Biodegradation of trace gases in simulated landfill soil cover systems.  

PubMed

The attenuation of methane and seven volatile organic compounds (VOCs) was investigated in a dynamic methane and oxygen counter gradient system simulating a landfill soil cover. The VOCs investigated were: Tetrachloromethane (TeCM), trichloromethane (TCM), dichloromethane (DCM), trichloroethylene (TCE), vinyl chloride (VC), benzene, and toluene. Soil was sampled at Skellingsted landfill, Denmark. The soil columns showed a high capacity for methane oxidation, with oxidation rates up to 184 g/m2/d corresponding to a 77% reduction of inlet methane. Maximal methane oxidation occurred at 15-20 cm depth, in the upper part of the column where there were overlapping gradients of methane and oxygen. All the chlorinated hydrocarbons were degraded in the active soil columns with removal efficiencies higher than 57%. Soil gas concentration profiles indicated that the removal of the fully chlorinated compound TeCM was because of anaerobic degradation, whereas the degradation of lower chlorinated compounds like VC and DCM was located in the upper oxic part of the column. Benzene and toluene were also removed in the active column. This study demonstrates the complexity of landfill soil cover systems and shows that both anaerobic and aerobic bacteria may play an important role in reducing the emission of trace components into the atmosphere. PMID:16111127

Scheutz, Charlotte; Kjeldsen, Peter

2005-07-01

11

Exopolysaccharide control of methane oxidation in landfill cover soil  

SciTech Connect

The study objective was to examine whether a relationship exists between the accumulation of exopolymeric substances (EPS) in landfill cover soil and the gradual decline in biotic methane oxidation observed in laboratory soil columns sparged with synthetic landfill gas. A mathematical model that combined multicomponent gas diffusion along the vertical axis of the columns with biotic methane oxidation was used to predict vertical gas gradients in the columns. An initial trial assumed methane oxidizers were embedded in a thin base layer of biofilm coating the soil, and the model predictions fit experimental data from soil columns early in their operating period. A second trial modeled the same system with a thick EPS layer coating the base biofilm and limiting diffusion of gases into and out of the cells. Predictions from the alter trials fit experimental data from soil columns later in their operating period when lower methane consumption rates were observed. The model results suggest that EPS accumulation may regulate methane oxidation rates in landfill covers.

Hilger, H.A.; Liehr, S.K.; Barlaz, M.A.

1999-12-01

12

Temporal variability of soil gas composition in landfill covers.  

PubMed

In order to assess the temporal variability of the conditions for the microbial oxidation of methane in landfill cover soils and their driving variables, gas composition at non-emissive and strongly emissive locations (hotspots) was monitored on a seasonal, daily and hourly time scale on an old, unlined landfill in northern Germany. Our study showed that the impact of the various environmental factors varied with the mode of gas transport and with the time scale considered. At non-emissive sites, governed by diffusive gas transport, soil gas composition was subject to a pronounced seasonal variation. A high extent of aeration, low methane concentrations and a high ratio of CO(2) to CH(4) were found across the entire depth of the soil cover during the warm and dry period, whereas in the cool and moist period aeration was less and landfill gas migrated further upward. Statistically, variation in soil gas composition was best explained by the variation in soil temperature. At locations dominated by advective gas transport and showing considerable emissions of methane, this pattern was far less pronounced with only little increase in the extent of aeration during drier periods. Here, the change of barometric pressure was found to impact soil gas composition. On a daily scale under constant conditions of temperature, gas transport at both types of locations was strongly impacted by the change in soil moisture. On an hourly scale, under constant conditions of temperature and moisture, gas migration was impacted most by the change in barometric pressure. It was shown that at diffusion-dominated sites complete methane oxidation was achieved even under adverse wintry conditions, whereas at hotspots, even under favorable dry and warm conditions, aerobic biological activity can be limited to the upper crust of the soil. PMID:21074982

Gebert, Julia; Rachor, Ingke; Gröngröft, Alexander; Pfeiffer, Eva-Maria

2011-05-01

13

Limits and dynamics of methane oxidation in landfill cover soils.  

PubMed

In order to understand the limits and dynamics of methane (CH(4)) oxidation in landfill cover soils, we investigated CH(4) oxidation in daily, intermediate, and final cover soils from two California landfills as a function of temperature, soil moisture and CO(2) concentration. The results indicate a significant difference between the observed soil CH(4) oxidation at field sampled conditions compared to optimum conditions achieved through pre-incubation (60 days) in the presence of CH(4) (50 ml l(-1)) and soil moisture optimization. This pre-incubation period normalized CH(4) oxidation rates to within the same order of magnitude (112-644 ?g CH(4) g(-1) day(-1)) for all the cover soils samples examined, as opposed to the four orders of magnitude variation in the soil CH(4) oxidation rates without this pre-incubation (0.9-277 ?g CH(4) g(-1) day(-1)). Using pre-incubated soils, a minimum soil moisture potential threshold for CH(4) oxidation activity was estimated at 1500 kPa, which is the soil wilting point. From the laboratory incubations, 50% of the oxidation capacity was inhibited at soil moisture potential drier than 700 kPa and optimum oxidation activity was typical observed at 50 kPa, which is just slightly drier than field capacity (33 kPa). At the extreme temperatures for CH(4) oxidation activity, this minimum moisture potential threshold decreased (300 kPa for temperatures <5°C and 50 kPa for temperatures >40°C), indicating the requirement for more easily available soil water. However, oxidation rates at these extreme temperatures were less than 10% of the rate observed at more optimum temperatures (? 30°C). For temperatures from 5 to 40°C, the rate of CH(4) oxidation was not limited by moisture potentials between 0 (saturated) and 50 kPa. The use of soil moisture potential normalizes soil variability (e.g. soil texture and organic matter content) with respect to the effect of soil moisture on methanotroph activity. The results of this study indicate that the wilting point is the lower moisture threshold for CH(4) oxidation activity and optimum moisture potential is close to field capacity. No inhibitory effects of elevated CO(2) soil gas concentrations were observed on CH(4) oxidation rates. However, significant differences were observed for diurnal temperature fluctuations compared to thermally equivalent daily isothermal incubations. PMID:20096554

Spokas, Kurt A; Bogner, Jean E

2011-05-01

14

Influence of Physical Parameters on Methane Oxidation in Landfill Cover Soils  

Microsoft Academic Search

Methane emissions from landfills make an important contribution to the anthropogenic induced global warming, and it has been estimated that landfills are responsible for a major part of anthropogenic methane emission. Landfill cover soils are identified to have a huge potential for methane oxidation trough methanotrophs. There are several research efforts to investigate the optimum composition of cover soil to

Katherine Gómez

15

Simulation model for gas diffusion and methane oxidation in landfill cover soils  

Microsoft Academic Search

Landfill cover soils oxidize a considerable fraction of the methane produced by landfilled waste. Despite many efforts this oxidation is still poorly quantified. In order to reduce the uncertainties associated with methane oxidation in landfill cover soils, a simulation model was developed that incorporates Stefan–Maxwell diffusion, methane oxidation, and methanotrophic growth. The growth model was calibrated to laboratory data from

Alex De Visscher; Oswald Van Cleemput

2003-01-01

16

Spatial variability of soil gas concentration and methane oxidation capacity in landfill covers  

Microsoft Academic Search

In order to devise design criteria for biocovers intended to enhance the microbial oxidation of landfill methane it is critical to understand the factors influencing gas migration and methane oxidation in landfill cover soils. On an old municipal solid waste landfill in north-western Germany soil gas concentrations (10, 40, 90cm depth), topsoil methane oxidation capacity and soil properties were surveyed

Inga Ute Röwer; Christoph Geck; Julia Gebert; Eva-Maria Pfeiffer

2011-01-01

17

Impact assessment of intermediate soil cover on landfill stabilization by characterizing landfilled municipal solid waste.  

PubMed

Waste samples at different depths of a covered municipal solid waste (MSW) landfill in Beijing, China, were excavated and characterized to investigate the impact of intermediate soil cover on waste stabilization. A comparatively high amount of unstable organic matter with 83.3 g kg(-1) dry weight (dw) total organic carbon was detected in the 6-year-old MSW, where toxic inorganic elements containing As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn of 10.1, 0.98, 85.49, 259.7, 530.4, 30.5, 84.0, and 981.7 mg kg(-1) dw, respectively, largely accumulated because of the barrier effect of intermediate soil cover. This accumulation resulted in decreased microbial activities. The intermediate soil cover also caused significant reduction in moisture in MSW under the soil layer, which was as low as 25.9%, and led to inefficient biodegradation of 8- and 10-year-old MSW. Therefore, intermediate soil cover with low permeability seems to act as a barrier that divides a landfill into two landfill cells with different degradation processes by restraining water flow and hazardous matter. PMID:23764507

Qi, Guangxia; Yue, Dongbei; Liu, Jianguo; Li, Rui; Shi, Xiaochong; He, Liang; Guo, Jingting; Miao, Haomei; Nie, Yongfeng

2013-10-15

18

Earthworm activity in a simulated landfill cover soil shifts the community composition of active methanotrophs.  

PubMed

Landfills represent a major source of methane in the atmosphere. In a previous study, we demonstrated that earthworm activity in landfill cover soil can increase soil methane oxidation capacity. In this study, a simulated landfill cover soil mesocosm (1 m × 0.15 m) was used to observe the influence of earthworms (Eisenia veneta) on the active methanotroph community composition, by analyzing the expression of the pmoA gene, which is responsible for methane oxidation. mRNA-based pmoA microarray analysis revealed that earthworm activity in landfill cover soil stimulated activity of type I methanotrophs (Methylobacter, Methylomonas, Methylosarcina spp.) compared to type II methanotrophs (particularly Methylocystis spp.). These results, along with previous studies of methanotrophs in landfill cover soil, can now be used to plan in situ field studies to integrate earthworm-induced methanotrophy with other landfill management practises in order to maximize soil methane oxidation and reduce methane emissions from landfills. PMID:21925596

Kumaresan, Deepak; Héry, Marina; Bodrossy, Levente; Singer, Andrew C; Stralis-Pavese, Nancy; Thompson, Ian P; Murrell, J Colin

2011-12-01

19

Earthworm activity in a simulated landfill cover soil shifts the community composition of active methanotrophs  

Microsoft Academic Search

Landfills represent a major source of methane in the atmosphere. In a previous study, we demonstrated that earthworm activity in landfill cover soil can increase soil methane oxidation capacity. In this study, a simulated landfill cover soil mesocosm (1 m × 0.15 m) was used to observe the influence of earthworms (Eisenia veneta) on the active methanotroph community composition, by analyzing the expression of

Deepak Kumaresan; Marina Héry; Levente Bodrossy; Andrew C. Singer; Nancy Stralis-Pavese; Ian P. Thompson; J. Colin Murrell

20

Strategies to Optimize Microbially-Mediated Mitigation of Greenhouse Gas Emissions from Landfill Cover Soils  

Microsoft Academic Search

The overall objective of this project, 'Strategies to Optimize Microbially-Mediated Mitigation of Greenhouse Gas Emissions from Landfill Cover Soils' was to develop effective, efficient, and economic methodologies by which microbial production of nitrous oxide can be minimized while also maximizing microbial consumption of methane in landfill cover soils. A combination of laboratory and field site experiments found that the addition

Jeremy Semrau; Sung-Woo Lee; Jeongdae Im; Sukhwan Yoon; Michael Barcelona

2010-01-01

21

Rapid methane oxidation in a landfill cover soil.  

PubMed

Methane oxidation rates observed in a topsoil covering a retired landfill are the highest reported (45 g m day) for any environment. This microbial community had the capacity to rapidly oxidize CH(4) at concentrations ranging from <1 ppm (microliters per liter) (first-order rate constant [k] = -0.54 h) to >10 ppm (k = -2.37 h). The physiological characteristics of a methanotroph isolated from the soil (characteristics determined in aqueous medium) and the natural population, however, were similar to those of other natural populations and cultures: the Q(10) and optimum temperature were 1.9 and 31 degrees C, respectively, the apparent half-saturation constant was 2.5 to 9.3 muM, and 19 to 69% of oxidized CH(4) was assimilated into biomass. The CH(4) oxidation rate of this soil under waterlogged (41% [wt/vol] H(2)O) conditions, 6.1 mg liter day, was near rates reported for lake sediment and much lower than the rate of 116 mg liter day in the same soil under moist (11% H(2)O) conditions. Since there are no large physiological differences between this microbial community and other CH(4) oxidizers, we attribute the high CH(4) oxidation rate in moist soil to enhanced CH(4) transport to the microorganisms; gas-phase molecular diffusion is 10-fold faster than aqueous diffusion. These high CH(4) oxidation rates in moist soil have implications that are important in global climate change. Soil CH(4) oxidation could become a negative feedback to atmospheric CH(4) increases (and warming) in areas that are presently waterlogged but are projected to undergo a reduction in summer soil moisture. PMID:16348346

Whalen, S C; Reeburgh, W S; Sandbeck, K A

1990-11-01

22

Rapid methane oxidation in a landfill cover soil  

SciTech Connect

Methane oxidation rates observed in a topsoil covering a retired landfill are the highest reported (45 g m{sup {minus}2} day{sup {minus}1}) for any environment. This microbial community had the capacity to rapidly oxidize CH{sub 4} at concentrations ranging from <1 ppm (microfilters per liter) (first-order rate constant (k) = {minus}0.54 h{sup {minus}1}) to >10{sup 4} ppm (k = {minus}2.37 h{sup {minus}1}). The physiological characteristics of a methanotroph isolated from the soil (characteristics determined in aqueous medium) and the natural population, however, were similar to those of other natural populations and cultures: the Q{sub 10} and optimum temperature were 1.9 and 31{degree}C, respectively, the apparent half-saturation constant was 2.5 to 9.3 {mu}M, and 19 to 69% of oxidized CH{sub 4} was assimilated into biomass. The CH{sub 4} oxidation rate of this soil was waterlogged (41% (wt/vol) H{sub 2}O) conditions, 6.1 mg liter{sup {minus}1} day{sup {minus}1}, was near rates reported for lake sediment and much lower than the rate of 116 mg liter{sup {minus}1} day{sup {minus}1} in the same soil under moist (11% H{sub 2}O) conditions. Since there are no large physiological differences between this microbial community and other CH{sub 4} oxidizers, we attribute the high CH{sub 4} oxidation rate in moist soil to enhanced CH{sub 4} transport to the microorganisms; gas-phase molecular diffusion is 10{sup 4}-fold faster than aqueous diffusion. These high CH{sub 4} oxidation rates in moist soil have implications that are important in global climate change. Soil CH{sub 4} oxidation could become a negative feedback to atmospheric CH{sub 4} increases (and warming) in areas that are presently waterlogged but are projected to undergo a reduction in summer soil moisture.

Whalen, S.C.; Reeburgh, W.S.; Sandbeck, K.A. (Univ. of Alaska, Fairbanks (USA))

1990-11-01

23

Rapid methane oxidation in a landfill cover soil  

Microsoft Academic Search

Methane oxidation rates observed in a topsoil covering a retired landfill are the highest reported (45 g m⁻² day⁻¹) for any environment. This microbial community had the capacity to rapidly oxidize CHâ at concentrations ranging from <1 ppm (microfilters per liter) (first-order rate constant (k) = -0.54 h⁻¹) to >10⁴ ppm (k = -2.37 h⁻¹). The physiological characteristics of a

S. C. Whalen; W. S. Reeburgh; K. A. Sandbeck

1990-01-01

24

Short-term kinetic response of enhanced methane oxidation in landfill cover soils to environmental factors  

Microsoft Academic Search

This paper aims at a better understanding of methane oxidation under conditions that are representative of landfill cover\\u000a soils. The kinetics of methane oxidation were studied in landfill cover soils that had been exposed to high methane mixing\\u000a ratios. This was done in batch experiments, under various environmental conditions. V\\u000a max increased exponentially with temperature in the range 5–35??C, with

A. De Visscher; Michael Schippers; Oswald Van Cleemput

2001-01-01

25

Isotope fractionation effects by diffusion and methane oxidation in landfill cover soils  

Microsoft Academic Search

When the open system isotope method has been used to determine the methane oxidation efficiency of a landfill cover soil, it has been assumed that gas transport from the landfill is primarily driven by advection, a mechanism that is not associated with isotopic fractionation. A controlled laboratory experiment revealed that this approach underestimated the methane oxidation efficiency because it underestimated

Alex De Visscher; Ingrid De Pourcq; Jeffrey Chanton

2004-01-01

26

Relevance of soil physical properties for the microbial oxidation of methane in landfill covers  

Microsoft Academic Search

The microbial oxidation of methane in landfill cover soils offers great potential to reduce methane emissions from landfills. High methane degradation rates can only be accomplished if the supply of atmospheric oxygen to the methanotrophic community is adequate. Thus, if environmental variables such as pH or nutrient status are not limiting, system performance is suggested to be governed by the

Julia Gebert; Alexander Groengroeft; Eva-Maria Pfeiffer

2011-01-01

27

Modeling of methane oxidation in landfill cover soil using an artificial neural network.  

PubMed

Knowing the fraction of methane (CH4) oxidized in landfill cover soils is an important step in estimating the total CH4 emissions from any landfill. Predicting CH4 oxidation in landfill cover soils is a difficult task because it is controlled by a number of biological and environmental factors. This study proposes an artificial neural network (ANN) approach using feedforward backpropagation to predict CH4 oxidation in landfill cover soil in relation to air temperature, soil moisture content, oxygen (O2) concentration at a depth of 10 cm in cover soil, and CH4 concentration at the bottom of cover soil. The optimum ANN model giving the lowest mean square error (MSE) was configured from three layers, with 12 and 9 neurons at the first and the second hidden layers, respectively, log-sigmoid (logsig) transfer function at the hidden and output layers, and the Levenberg-Marquardt training algorithm. This study revealed that the ANN oxidation model can predict CH4 oxidation with a MSE of 0.0082, a coefficient of determination (R2) between the measured and predicted outputs of up to 0.937, and a model efficiency (E) of 0.8978. To conclude, further developments of the proposed ANN model are required to generalize and apply the model to other landfills with different cover soil properties. PMID:24654384

Abushammala, Mohammed F M; Basri, Noor Ezlin Ahmad; Elfithri, Rahmah; Younes, Mohammad K; Irwan, Dani

2014-02-01

28

Comparison of Methods to Assess the Fate of Methane in a Landfill-Cover Soil  

NASA Astrophysics Data System (ADS)

A substantial fraction of the greenhouse gas methane released into the atmosphere is produced in terrestrial environments such as wetlands, rice paddy fields, and landfills. However, the amount of methane that is emitted from these environments is often reduced by microbial methane oxidation, mediated by methanotrophic microorganisms. Methanotrophs are ubiquitous in soils and represent the largest biological sink for methane. We performed a series of field experiments in summer 2008 to compare several state-of- the-art methods to assess the fate of methane in a landfill-cover soil near Liestal (BL), Switzerland. Methods employed included eddy-covariance and field-chamber measurements to quantify net methane flux at the landfill surface. In addition, methane concentrations at the landfill surface were monitored using a portable methane detector. Methane fluxes within the cover soil were estimated from methane-concentration profiles in conjunction with radon measurements. Additionally, gas push-pull tests were employed for in-situ quantification of methane oxidation in the cover soil. Finally, methane stable-carbon-isotope measurements were conducted to corroborate methane oxidation in the cover soil. Preliminary results indicate that each method provides unique information, and when combined, the data provide detailed insight in the fate of methane in the cover soil. The investigated landfill-cover soil appears to be ordinarily a net sink for methane. However, it can quickly turn into a net source of methane under adverse meteorological conditions.

Gomez, K. E.; Schroth, M. H.; Eugster, W.; Niklaus, P.; Oester, P.; Zeyer, J.

2008-12-01

29

Assessment of the methane oxidation capacity of compacted soils intended for use as landfill cover materials  

Microsoft Academic Search

The microbial oxidation of methane in engineered cover soils is considered a potent option for the mitigation of emissions from old landfills or sites containing wastes of low methane generation rates. A laboratory column study was conducted in order to derive design criteria that enable construction of an effective methane oxidising cover from the range of soils that are available

Ingke Rachor; Julia Gebert; Alexander Groengroeft; Eva-Maria Pfeiffer

2011-01-01

30

ENHANCEMENT OF METHANE OXIDATION IN COVER SOIL OF TROPICAL LANDFILL BY VEGETATION AND LEACHATE IRRIGATION  

Microsoft Academic Search

The effect of vegetation and leachate irrigation on methanotrophic activity in cover soil of landfill was investigated. Leachate was applied to maintain moisture content for microbial activity while being treated when irrigated on topsoil. Laboratory-scale experiment was conducted to examine the effect of leachate loading on methane oxidation in non-vegetated and vegetated cover soil (with S. virginicus, a tropical grass).

Sayan Tudsri

31

Methane oxidation in landfill cover soils, as revealed by potential oxidation measurements and phospholipid fatty acid analyses  

Microsoft Academic Search

Landfills account for ca. 10% of the annual global burden of atmospheric methane. Part of the efflux is mitigated by means of biological methane oxidation in the landfill covers. In this study, two types of landfill cover soils (mineral soil and sewage sludge) were compared with respect to methane emissions as well as potential methane oxidation capacity and the PLFA

Gunnar Börjesson; Ingvar Sundh; Anders Tunlid; Bo H. Svensson

1998-01-01

32

Methane emissions from MSW landfill with sandy soil covers under leachate recirculation and subsurface irrigation  

NASA Astrophysics Data System (ADS)

CH 4 emissions and leachate disposal are recognized as the two major concerns in municipal solid waste (MSW) landfills. Recently, leachate recirculation was attempted to accelerate land-filled waste biodegradation and thus enhanced landfill gas generation. Leachate irrigation was also conducted for volume reduction effectively. Nevertheless, the impacts of leachate recirculation and irrigation on landfill CH 4 emissions have not been previously reported. A field investigation of landfill CH 4 emissions was conducted on selected sandy soil cover with leachate recirculation and subsurface irrigation based on whole year around measurement. The average CH 4 fluxes were 311±903, 207±516, and 565±1460 CH 4 m -2 h -1 from site A without leachate recirculation and subsurface irrigation, lift B2 with leachate subsurface irrigation, and lift B1 with both leachate recirculation and subsurface irrigation, respectively. Both gas recovery and cover soil oxidation minimized CH 4 emissions efficiently, while the later might be more pronounced when the location was more than 5 m away from gas recovery well. After covered by additional clay soil layer, CH 4 fluxes dropped by approximately 35 times in the following three seasons compared to the previous three seasons in lift B2. The diurnal peaks of CH 4 fluxes occurred mostly followed with air or soil temperature in the daytimes. The measured CH 4 fluxes were much lower than those of documented data from the landfills, indicating that the influences of leachate recirculation and subsurface irrigation on landfill CH 4 emissions might be minimized with the help of a well-designed sandy soil cover. Landfill cover composed of two soil layers (clay soil underneath and sandy soil above) is suggested as a low-cost and effective alternative to minimize CH 4 emissions.

Zhang, Houhu; He, Pinjing; Shao, Liming

33

Simulation model for gas diffusion and methane oxidation in landfill cover soils.  

PubMed

Landfill cover soils oxidize a considerable fraction of the methane produced by landfilled waste. Despite many efforts this oxidation is still poorly quantified. In order to reduce the uncertainties associated with methane oxidation in landfill cover soils, a simulation model was developed that incorporates Stefan-Maxwell diffusion, methane oxidation, and methanotrophic growth. The growth model was calibrated to laboratory data from an earlier study. There was an excellent agreement between the model and the experimental data. Therefore, the model is highly applicable to laboratory column studies, but it has not been validated with field data. A sensitivity analysis showed that the model is most sensitive to the parameter expressing the maximum attainable methanotrophic activity of the soil. Temperature and soil moisture are predicted to be the environmental factors affecting the methane oxidizing capacity of a landfill cover soil the most. Once validated with field data, the model will enable a year-round estimate of the methane oxidizing capacity of a landfill cover soil. PMID:12957153

De Visscher, Alex; Van Cleemput, Oswald

2003-01-01

34

Microbial mitigation of greenhouse gas emissions from landfill cover soils  

Microsoft Academic Search

Landfills are one of the major sources of methane (CH4), a potent greenhouse gas with a global warming potential (GWP) ˜23 times higher than that of carbon dioxide (CO2). Although some effective strategies have been formulated to prevent methane emissions from large landfills, many landfills allow methane to be freely emitted to the atmosphere. In such situations, it is often

Sung-Woo Lee

2008-01-01

35

Effect of leachate irrigation on methane oxidation in tropical landfill cover soil  

Microsoft Academic Search

The effect of leachate irrigation on methanotrophic activity in sandy loam-based landfill cover soil with vegetation was investigated.\\u000a Laboratory-scale experiments were conducted to investigate the methane oxidation reaction in cover soil with and without plants\\u000a (tropical grass). The methane oxidation rate in soil columns was monitored during leachate application at different organic\\u000a concentrations and using different irrigation patterns. The results

Chart Chiemchaisri; Wilai Chiemchaisri; Kittipon Chittanukul; Wiwattana Soontornlerdwanich; Nathiya Tanthachoon

2010-01-01

36

Methane emission from a landfill and the methane oxidising capacity of its covering soil  

Microsoft Academic Search

Methane emission from a small covered landfill site showed, seasonally varying fluxes, ranging from ?5.9 to 914.3 mg CH4 m?2 d?1. The moisture content of the CH4-oxidising cover soil was thought to cause this variation. Comparing gross and net CH4 emission rates, it was found that the cover soil, due to its CH4 oxidising capacity, had a large mitigating effect

Pascal Boeckx; Oswald van Cleemput; Ida Villaralvo

1996-01-01

37

Enumeration of Methanotrophic Bacteria in the Cover Soil of an Aged Municipal Landfill  

Microsoft Academic Search

The enumeration of methanotrophic bacteria in the cover soil of an aged municipal landfill was carried out using (1) fluorescent\\u000a in situ hybridization (FISH) with horseradish peroxidase-labeled oligonucleotide probes and tyramide signal amplification, also known\\u000a as catalyzed reporter deposition-FISH (CARD-FISH), and (2) most probable number (MPN) method. The number of methanotrophs\\u000a was determined in cover soil samples collected during April–November

A. Yu. Kallistova; M. V. Kevbrina; V. K. Nekrasova; N. A. Shnyrev; J. K. M. Einola; M. S. Kulomaa; J. A. Rintala; A. N. Nozhevnikova

2007-01-01

38

Minimizing N 2O fluxes from full-scale municipal solid waste landfill with properly selected cover soil  

Microsoft Academic Search

Municipal solid waste landfills emit nitrous oxide (N2O) gas. Assuming that the soil cover is the primary N2O source from landfills, this study tested, during a four-year project, the hypothesis that the proper use of chosen soils with fine texture minimizes N2O emissions. A full-scale sanitary landfill, a full-scale bioreactor landfill and a cell planted with Nerium indicum or Festuca

Houhu ZHANG; Pinjing HE; Liming SHAO; Xian QU; Duujong LEE

2008-01-01

39

Effects of methane on the microbial populations and oxidation rates in different landfill cover soil columns.  

PubMed

A considerable fraction of methane produced in landfills is oxidized by landfill cover soils. In this work, microbial populations and oxidation rates developed in response to the presence of methane were studied in three soil columns simulated landfill cover soil environments. The population of aerobic heterotrophic bacteria was highest in the waste soil, middle in the clay soil, and lowest in the red soil. After exposure to methane-rich environments, the populations of methanotrophic bacteria showed increases in the waste and clay soils. The population of methanotrophic bacteria increased from 30.77x10(4) to 141.77x10(4) cfu g d.w.-1 in the middle layer of the waste soil column as a function of exposure to methane for 120 days. The populations of methanotrophic bacteria were correlated with the potential methane oxidation rates in the waste and clay soils, respectively. The topsoil was observed to be dried in the three soil columns. Most of methane oxidation occurred at the depth of between 10 and 20 cm in the waste soil column, while it took place mainly at the depth of between 20 and 30 cm in the clay soil column. PMID:17474005

He, Ruo; Ruan, Aidong; Shen, Dong-Sheng

2007-05-01

40

Transport and reaction processes affecting the attenuation of landfill gas in cover soils.  

PubMed

Methane and trace organic gases produced in landfill waste are partly oxidized in the top 40 cm of landfill cover soils under aerobic conditions. The balance between the oxidation of landfill gases and the ingress of atmospheric oxygen into the soil cover determines the attenuation of emissions of methane, chlorofluorocarbons, and hydrochlorofluorocarbons to the atmosphere. This study was conducted to investigate the effect of oxidation reactions on the overall gas transport regime and to evaluate the contributions of various gas transport processes on methane attenuation in landfill cover soils. For this purpose, a reactive transport model that includes advection and the Dusty Gas Model for simulation of multicomponent gas diffusion was used. The simulations are constrained by data from a series of counter-gradient laboratory experiments. Diffusion typically accounts for over 99% of methane emission to the atmosphere. Oxygen supply into the soil column is driven exclusively by diffusion, whereas advection outward offsets part of the diffusive contribution. In the reaction zone, methane consumption reduces the pressure gradient, further decreasing the significance of advection near the top of the column. Simulations suggest that production of water or accumulation of exopolymeric substances due to microbially mediated methane oxidation can significantly reduce diffusive fluxes. Assuming a constant rate of methane production within a landfill, reduction of the diffusive transport properties, primarily due to exopolymeric substance production, may result in reduced methane attenuation due to limited O(2) -ingress. PMID:18268309

Molins, S; Mayer, K U; Scheutz, C; Kjeldsen, P

2008-01-01

41

Assessment of the methane oxidation capacity of compacted soils intended for use as landfill cover materials.  

PubMed

The microbial oxidation of methane in engineered cover soils is considered a potent option for the mitigation of emissions from old landfills or sites containing wastes of low methane generation rates. A laboratory column study was conducted in order to derive design criteria that enable construction of an effective methane oxidising cover from the range of soils that are available to the landfill operator. Therefore, the methane oxidation capacity of different soils was assessed under simulated landfill conditions. Five sandy potential landfill top cover materials with varying contents of silt and clay were investigated with respect to methane oxidation and corresponding soil gas composition over a period of four months. The soils were compacted to 95% of their specific proctor density, resulting in bulk densities of 1.4-1.7 g cm(-3), reflecting considerably unfavourable conditions for methane oxidation due to reduced air-filled porosity. The soil water content was adjusted to field capacity, resulting in water contents ranging from 16.2 to 48.5 vol.%. The investigated inlet fluxes ranged from 25 to about 100g CH(4)m(-2)d(-1), covering the methane load proposed to allow for complete oxidation in landfill covers under Western European climate conditions and hence being suggested as a criterion for release from aftercare. The vertical distribution of gas concentrations, methane flux balances as well as stable carbon isotope studies allowed for clear process identifications. Higher inlet fluxes led to a reduction of the aerated zone, an increase in the absolute methane oxidation rate and a decline of the relative proportion of oxidized methane. For each material, a specific maximum oxidation rate was determined, which varied between 20 and 95 g CH(4)m(-2)d(-1) and which was positively correlated to the air-filled porosity of the soil. Methane oxidation efficiencies and gas profile data imply a strong link between oxidation capacity and diffusive ingress of atmospheric air. For one material with elevated levels of fine particles and high organic matter content, methane production impeded the quantification of methane oxidation potentials. Regarding the design of landfill cover layers it was concluded that the magnitude of the expected methane load, the texture and expected compaction of the cover material are key variables that need to be known. Based on these, a column study can serve as an appropriate testing system to determine the methane oxidation capacity of a soil intended as landfill cover material. PMID:21067907

Rachor, Ingke; Gebert, Julia; Gröngröft, Alexander; Pfeiffer, Eva-Maria

2011-05-01

42

Above- and below-ground methane fluxes and methanotrophic activity in a landfill-cover soil.  

PubMed

Landfills are a major anthropogenic source of the greenhouse gas methane (CH(4)). However, much of the CH(4) produced during the anaerobic degradation of organic waste is consumed by methanotrophic microorganisms during passage through the landfill-cover soil. On a section of a closed landfill near Liestal, Switzerland, we performed experiments to compare CH(4) fluxes obtained by different methods at or above the cover-soil surface with below-ground fluxes, and to link methanotrophic activity to estimates of CH(4) ingress (loading) from the waste body at selected locations. Fluxes of CH(4) into or out of the cover soil were quantified by eddy-covariance and static flux-chamber measurements. In addition, CH(4) concentrations at the soil surface were monitored using a field-portable FID detector. Near-surface CH(4) fluxes and CH(4) loading were estimated from soil-gas concentration profiles in conjunction with radon measurements, and gas push-pull tests (GPPTs) were performed to quantify rates of microbial CH(4) oxidation. Eddy-covariance measurements yielded by far the largest and probably most representative estimates of overall CH(4) emissions from the test section (daily mean up to ?91,500?molm(-2)d(-1)), whereas flux-chamber measurements and CH(4) concentration profiles indicated that at the majority of locations the cover soil was a net sink for atmospheric CH(4) (uptake up to -380?molm(-2)d(-1)) during the experimental period. Methane concentration profiles also indicated strong variability in CH(4) loading over short distances in the cover soil, while potential methanotrophic activity derived from GPPTs was high (v(max)?13mmolL(-1)(soil air)h(-1)) at a location with substantial CH(4) loading. Our results provide a basis to assess spatial and temporal variability of CH(4) dynamics in the complex terrain of a landfill-cover soil. PMID:22143049

Schroth, M H; Eugster, W; Gómez, K E; Gonzalez-Gil, G; Niklaus, P A; Oester, P

2012-05-01

43

Methanotrophic communities in a landfill cover soil as revealed by [ 13C] PLFAs and respiratory quinones: Impact of high methane addition and landfill leachate irrigation  

Microsoft Academic Search

The soil microbial communities of a landfill cover substrate, which was treated with landfill gas (100lCH4m?2d?1) and landfill leachate for 1.5 years, were investigated by phospholipid fatty acid (PLFA), ergosterol and respiratory quinone analyses. The natural 13C depletion of methane was used to assess the activity of methanotrophs and carbon turnover in the soil system. Under methane addition, the soil

Andrea Watzinger; Michael Stemmer; Michael Pfeffer; Frank Rasche; Thomas G. Reichenauer

2008-01-01

44

Methane oxidation in a neutral landfill cover soil: Influence of moisture content, temperature, and nitrogen-turnover  

Microsoft Academic Search

Well-managed, aerated cover soils can have a mitigating effect on methane emission from landfills. The influence of moisture content, soil temperature, and N on the methane uptake capacity of a neutral landfill cover soil was examined. A soil moisture content of 15% w\\/w gave the maximum CHâ oxidation rate (2.36 ng CHâ⁻¹g⁻¹ soil). When wetter, CHâ consumption was slower (e.g.,

Pascal Boeckx; Oswald Van Cleemput

1996-01-01

45

Utilisation of chemically stabilized arsenic-contaminated soil in a landfill cover.  

PubMed

The aim of the study was to determine if an As-contaminated soil, stabilized using zerovalent iron (Fe(0)) and its combination with gypsum waste, coal fly ash, peat, or sewage sludge, could be used as a construction material at the top layer of the landfill cover. A reproduction of 2 m thick protection/vegetation layer of a landfill cover using a column setup was used to determine the ability of the amendments to reduce As solubility and stimulate soil functionality along the soil profile. Soil amendment with Fe(0) was highly efficient in reducing As in soil porewater reaching 99 % reduction, but only at the soil surface. In the deeper soil layers (below 0.5 m), the Fe treatment had a reverse effect, As solubility increased dramatically exceeding that of the untreated soil or any other treatment by one to two orders of magnitude. A slight bioluminescence inhibition of Vibrio fischeri was detected in the Fe(0) treatment. Soil amendment with iron and peat showed no toxicity to bacteria and was the most efficient in reducing dissolved As in soil porewater throughout the 2 m soil profile followed by iron and gypsum treatment, most likely resulting from a low soil density and a good air diffusion to the soil. The least suitable combination of soil amendments for As immobilization was a mixture of iron with coal fly ash. An increase in all measured enzyme activities was observed in all treatments, particularly those receiving organic matter. For As to be stable in soil, a combination of amendments that can keep the soil porous and ensure the air diffusion through the entire soil layer of the landfill cover is required. PMID:23709267

Kumpiene, Jurate; Desogus, Paolo; Schulenburg, Sven; Arenella, Mariarita; Renella, Giancarlo; Brännvall, Evelina; Lagerkvist, Anders; Andreas, Lale; Sjöblom, Rolf

2013-12-01

46

Minimizing N2O fluxes from full-scale municipal solid waste landfill with properly selected cover soil.  

PubMed

Municipal solid waste landfills emit nitrous oxide (N2O) gas. Assuming that the soil cover is the primary N2O source from landfills, this study tested, during a four-year project, the hypothesis that the proper use of chosen soils with fine texture minimizes N2O emissions. A full-scale sanitary landfill, a full-scale bioreactor landfill and a cell planted with Nerium indicum or Festuca arundinacea Schreb, at the Hangzhou Tianziling landfill in Hangzhou City were the test sites. The N2O emission rates from all test sites were considerably lower than those reported in the published reports. Specifically, the N2O emission rate was dependent on soil water content and nitrate concentrations in the cover soil. The effects of leachate recirculation and irrigation were minimal. Properly chosen cover soils applied to the landfills reduced N2O flux. PMID:18574960

Zhang, Houhu; He, Pinjing; Shao, Liming; Qu, Xian; Lee, Duujong

2008-01-01

47

Modelling of stable isotope fractionation by methane oxidation and diffusion in landfill cover soils  

Microsoft Academic Search

A technique to measure biological methane oxidation in landfill cover soils that is gaining increased interest is the measurement of stable isotope fractionation in the methane. Usually to quantify methane oxidation, only fractionation by oxidation is taken into account. Recently it was shown that neglecting the isotope fractionation by diffusion results in underestimation of the methane oxidation. In this study

Koenraad Mahieu; Alex De Visscher; Peter A. Vanrolleghem; Oswald Van Cleemput

48

Modelling of stable isotope fractionation by methane oxidation and diffusion in landfill cover soils  

Microsoft Academic Search

A technique to measure biological methane oxidation in landfill cover soils that is gaining increased interest is the measurement of stable isotope fractionation in the methane. Usually to quantify methane oxidation, only fractionation by oxidation is taken into account. Recently it was shown that neglecting the isotope fractionation by diffusion results in underestimation of the methane oxidation. In this study

Koenraad Mahieu; Alex De Visscher; Peter A. Vanrolleghem; Oswald Van Cleemput

2008-01-01

49

Methanotrophic production of extracellular polysaccharide in landfill cover soils  

Microsoft Academic Search

A bench-scale soil reactor was used to study methane oxidation and EPS production under tropical conditions. The study of pertinent environmental factors affecting EPS production was carried out by batch cultivation of methanotrophs. These factors included variations in temperature (20°C to 45°C), soil water content (5% to 33%), and the supply ratios of methane\\/oxygen. The bench-scale study revealed that excessive

W. Chiemchaisri; J. S. Wu; C. Visvanathan

50

Methanotrophic production of extracellular polysaccharide in landfill cover soils.  

PubMed

A bench-scale soil reactor was used to study methane oxidation and EPS production under tropical conditions. The study of pertinent environmental factors affecting EPS production was carried out by batch cultivation of methanotrophs. These factors included variations in temperature (20 degrees C to 45 degrees C), soil water content (5% to 33%), and the supply ratios of methane/oxygen. The bench-scale study revealed that excessive EPS was accumulating in an active methane oxidation zone located 5-45 cm below the soil surface of the reactor. The observed peak rates of oxidation could not be sustained over an extended period of time due to EPS accumulation. Results from the batch cultivation experiments confirmed the production of EPS in soils subject to methane oxidation. EPS production was found to correlate with methane oxidation rates which, in turn, were regulated by the variance of temperature and soil water content. A larger amount of EPS production was obtained at 30 degrees C and 17% soil water content. Oxygen is required for methane oxidation; however, at high oxygen tension it may accelerate the production of EPS by methanotrophs causing limited oxygen diffusion and declining rates of methane oxidation. PMID:11381961

Chiemchaisri, W; Wu, J S; Visvanathan, C

2001-01-01

51

Spatial variability of soil gas concentration and methane oxidation capacity in landfill covers.  

PubMed

In order to devise design criteria for biocovers intended to enhance the microbial oxidation of landfill methane it is critical to understand the factors influencing gas migration and methane oxidation in landfill cover soils. On an old municipal solid waste landfill in north-western Germany soil gas concentrations (10, 40, 90 cm depth), topsoil methane oxidation capacity and soil properties were surveyed at 40 locations along a 16 m grid. As soil properties determine gas flow patterns it was hypothesized that the variability in soil gas composition and the subsequent methanotrophic activity would correspond to the variability of soil properties. Methanotrophic activity was found to be subject to high spatial variability, with values ranging between 0.17 and 9.80 g CH(4)m(-2)h(-1)(.) Considering the current gas production rate of 0.03 g CH(4)m(-2)h(-1), the oxidation capacity at all sampled locations clearly exceeded the flux to the cover, and can be regarded as an effective instrument for mitigating methane fluxes. The methane concentration in the cover showed a high spatial heterogeneity with values between 0.01 and 0.32 vol.% (10 cm depth), 22.52 vol.% (40 cm), and 36.85 vol.% (90 cm). The exposure to methane raised the oxidation capacity, suggested by a statistical correlation to an increase in methane concentration at 90 cm depth. Methane oxidation capacity was further affected by the methanotroph bacteria pH optimum and nutrient availability, and increased with decreasing pH towards neutrality, and increased with soluble ion concentration). Soil methane and carbon dioxide concentration increased with lower flow resistance of the cover, as represented by the soil properties of a reduced bulk density, increase in air capacity and in relative ground level. PMID:20943363

Röwer, Inga Ute; Geck, Christoph; Gebert, Julia; Pfeiffer, Eva-Maria

2011-05-01

52

Performance evaluation of intermediate cover soil barrier for removal of heavy metals in landfill leachate.  

PubMed

This pilot-scale study evaluated the use of intermediate cover soil barriers for removing heavy metals in leachate generated from test cells for co-disposed fly ash from municipal solid waste incinerators, ash melting plants, and shredder residue. Cover soil barriers were mixtures of Andisol (volcanic ash soil), waste iron powder, (grinder dust waste from iron foundries), and slag fragments. The cover soil barriers were installed in the test cells' bottom layer. Sorption/desorption is an important process in cover soil bottom barrier for removal of heavy metals in landfill leachate. Salt concentrations such as those of Na, K, and Ca in leachate were extremely high (often greater than 30 gL(-1)) because of high salt content in fly ash from ash melting plants. Concentrations of all heavy metals (nickel, manganese, copper, zinc, lead, and cadmium) in test cell leachates with a cover soil barrier were lower than those of the test cell without a cover soil barrier and were mostly below the discharge limit, probably because of dilution caused by the amount of leachate and heavy metal removal by the cover soil barrier. The cover soil barriers' heavy metal removal efficiency was calculated. About 50% of copper, nickel, and manganese were removed. About 20% of the zinc and boron were removed, but lead and cadmium were removed only slightly. Based on results of calculation of the Langelier saturation index and analyses of core samples, the reactivity of the cover soil barrier apparently decreases because of calcium carbonate precipitation on the cover soil barriers' surfaces. PMID:18842283

Suzuki, Kazuyuki; Anegawa, Aya; Endo, Kazuto; Yamada, Masato; Ono, Yusaku; Ono, Yoshiro

2008-11-01

53

Quantifying methane oxidation in a landfill-cover soil by gas push-pull tests  

SciTech Connect

Methane (CH{sub 4}) oxidation by aerobic methanotrophs in landfill-cover soils decreases emissions of landfill-produced CH{sub 4} to the atmosphere. To quantify in situ rates of CH{sub 4} oxidation we performed five gas push-pull tests (GPPTs) at each of two locations in the cover soil of the Lindenstock landfill (Liestal, Switzerland) over a 4 week period. GPPTs consist of the injection of a gas mixture containing CH{sub 4}, O{sub 2} and noble gas tracers followed by extraction from the same location. Quantification of first-order rate constants was based upon comparison of breakthrough curves of CH{sub 4} with either Ar or CH{sub 4} itself from a subsequent inactive GPPT containing acetylene as an inhibitor of CH{sub 4} oxidation. The maximum calculated first-order rate constant was 24.8 {+-} 0.8 h{sup -1} at location 1 and 18.9 {+-} 0.6 h{sup -1} at location 2. In general, location 2 had higher background CH{sub 4} concentrations in vertical profile samples than location 1. High background CH{sub 4} concentrations in the cover soil during some experiments adversely affected GPPT breakthrough curves and data interpretation. Real-time PCR verified the presence of a large population of methanotrophs at the two GPPT locations and comparison of stable carbon isotope fractionation of CH{sub 4} in an active GPPT and a subsequent inactive GPPT confirmed that microbial activity was responsible for the CH{sub 4} oxidation. The GPPT was shown to be a useful tool to reproducibly estimate in situ rates of CH{sub 4} oxidation in a landfill-cover soil when background CH{sub 4} concentrations were low.

Gomez, K.E. [Institute of Biogeochemistry and Pollutant Dynamics, ETH Zuerich, Universitaetstrasse 16, 8092 Zuerich (Switzerland)], E-mail: gomezke@hotmail.com; Gonzalez-Gil, G.; Lazzaro, A. [Institute of Biogeochemistry and Pollutant Dynamics, ETH Zuerich, Universitaetstrasse 16, 8092 Zuerich (Switzerland); Schroth, M.H. [Institute of Biogeochemistry and Pollutant Dynamics, ETH Zuerich, Universitaetstrasse 16, 8092 Zuerich (Switzerland)], E-mail: martin.schroth@env.ethz.ch

2009-09-15

54

Quantifying methane oxidation in a landfill-cover soil by gas push-pull tests.  

PubMed

Methane (CH(4)) oxidation by aerobic methanotrophs in landfill-cover soils decreases emissions of landfill-produced CH(4) to the atmosphere. To quantify in situ rates of CH(4) oxidation we performed five gas push-pull tests (GPPTs) at each of two locations in the cover soil of the Lindenstock landfill (Liestal, Switzerland) over a 4 week period. GPPTs consist of the injection of a gas mixture containing CH(4), O(2) and noble gas tracers followed by extraction from the same location. Quantification of first-order rate constants was based upon comparison of breakthrough curves of CH(4) with either Ar or CH(4) itself from a subsequent inactive GPPT containing acetylene as an inhibitor of CH(4) oxidation. The maximum calculated first-order rate constant was 24.8+/-0.8 h(-1) at location 1 and 18.9+/-0.6 h(-1) at location 2. In general, location 2 had higher background CH(4) concentrations in vertical profile samples than location 1. High background CH(4) concentrations in the cover soil during some experiments adversely affected GPPT breakthrough curves and data interpretation. Real-time PCR verified the presence of a large population of methanotrophs at the two GPPT locations and comparison of stable carbon isotope fractionation of CH(4) in an active GPPT and a subsequent inactive GPPT confirmed that microbial activity was responsible for the CH(4) oxidation. The GPPT was shown to be a useful tool to reproducibly estimate in situ rates of CH(4) oxidation in a landfill-cover soil when background CH(4) concentrations were low. PMID:19525106

Gómez, K E; Gonzalez-Gil, G; Lazzaro, A; Schroth, M H

2009-09-01

55

N 2O emissions at municipal solid waste landfill sites: Effects of CH 4 emissions and cover soil  

NASA Astrophysics Data System (ADS)

Municipal solid waste landfills are the significant anthropogenic sources of N 2O due to the cooxidation of ammonia by methane-oxidizing bacteria in cover soils. Such bacteria could be developed through CH 4 fumigation, as evidenced by both laboratory incubation and field measurement. During a 10-day incubation with leachate addition, the average N 2O fluxes in the soil samples, collected from the three selected landfill covers, were multiplied by 1.75 ( p < 0.01), 3.56 ( p < 0.01), and 2.12 ( p < 0.01) from the soil samples preincubated with 5% CH 4 for three months when compared with the control, respectively. Among the three selected landfill sites, N 2O fluxes in two landfill sites were significantly correlated with the variations of the CH 4 emissions without landfill gas recovery ( p < 0.001). N 2O fluxes were also elevated by the increase of the CH 4 emissions with landfill gas recovery in another landfill site ( p > 0.05). The annual average N 2O flux was 176 ± 566 ?g N 2O-N m -2 h -1 ( p < 0.01) from sandy soil-covered landfill site, which was 72% ( p < 0.05) and 173% ( p < 0.01) lower than the other two clay soil covered landfill sites, respectively. The magnitude order of N 2O emissions in three landfill sites was also coincident by the results of laboratory incubation, suggesting the sandy soil cover could mitigate landfill N 2O emissions.

Zhang, Houhu; He, Pinjing; Shao, Liming

56

N 2O emissions from municipal solid waste landfills with selected infertile cover soils and leachate subsurface irrigation  

Microsoft Academic Search

This study presents the field investigations into the effects of cover soils and leachate subsurface irrigation on N2O emissions from municipal solid waste landfills. Landfill Site A and Site B, covered with carefully chosen infertile soils, were selected to monitor their diurnal and seasonal variations of N2O emissions. The annual average N2O flux was 469±796?gN2O-Nm?2h?1 in Site B with leachate

Hou-Hu Zhang; Pin-Jing He; Li-Ming Shao

2008-01-01

57

Microbial oxidation of CH(4) at different temperatures in landfill cover soils.  

PubMed

Biological oxidation of CH(4) is an important constraint on the emission of this gas from areas, such as landfills to the atmosphere. We studied the effect of temperature on methanotrophic bacteria in three different landfill cover soils, incubated in the laboratory. In samples of a young cover, consisting of wood chips and sewage sludge, the phospholipid fatty acids (PLFAs), regarded as biomarkers for type I methanotrophs (16:1omega5t, 16:1omega6c, 16:1omega8c), primarily increased at low temperatures (5-10 degrees C). On the other hand, the PLFA marker for type II methanotrophs (18:1omega8c) was highly elevated only at 20 degrees C. These results suggest that temperature can determine the selection of methanotroph populations. PMID:19712300

Börjesson, Gunnar; Sundh, Ingvar; Svensson, Bo

2004-06-01

58

Structure and function of methanotrophic communities in a landfill-cover soil.  

PubMed

In landfill-cover soils, aerobic methane-oxidizing bacteria (MOB) convert CH(4) to CO(2), mitigating emissions of the greenhouse gas CH(4) to the atmosphere. We investigated overall MOB community structure and assessed spatial differences in MOB diversity, abundance and activity in a Swiss landfill-cover soil. Molecular cloning, terminal restriction-fragment length polymorphism (T-RFLP) and quantitative PCR of pmoA genes were applied to soil collected from 16 locations at three different depths to study MOB community structure, diversity and abundance; MOB activity was measured in the field using gas push-pull tests. The MOB community was highly diverse but dominated by Type Ia MOB, with novel pmoA sequences present. Type II MOB were detected mainly in deeper soil with lower nutrient and higher CH(4) concentrations. Substantial differences in MOB community structure were observed between one high- and one low-activity location. MOB abundance was highly variable across the site [4.0 × 10(4) to 1.1 × 10(7) (g soil dry weight)(-1)]. Potential CH(4) oxidation rates were high [1.8-58.2 mmol CH(4) (L soil air)(-1) day(-1) ] but showed significant lateral variation and were positively correlated with mean CH(4) concentrations (P < 0.01), MOB abundance (P < 0.05) and MOB diversity (weak correlation, P < 0.17). Our findings indicate that Methylosarcina and closely related MOB are key players and that MOB abundance and community structure are driving factors in CH(4) oxidation at this landfill. PMID:22172054

Henneberger, Ruth; Lüke, Claudia; Mosberger, Lona; Schroth, Martin H

2012-07-01

59

Isotope fractionation effects by diffusion and methane oxidation in landfill cover soils  

NASA Astrophysics Data System (ADS)

When the open system isotope method has been used to determine the methane oxidation efficiency of a landfill cover soil, it has been assumed that gas transport from the landfill is primarily driven by advection, a mechanism that is not associated with isotopic fractionation. A controlled laboratory experiment revealed that this approach underestimated the methane oxidation efficiency because it underestimated the importance of molecular diffusion during gas transport. In a worst-case scenario laboratory column experiment where diffusion was an important gas transport mode, a comparison between a mass balance and the open system isotope method revealed that the latter underestimated methane oxidation by a factor 2 to 4. The vertical profile of the ?13C value of methane in the column confirmed that isotope fractionation associated with gas transport occurred. Similar profiles were observed in the field, but the effect was less pronounced. It is concluded that the isotope method as currently applied produces a conservative estimate of methane oxidation by landfill cover soils.

de Visscher, Alex; de Pourcq, Ingrid; Chanton, Jeffrey

2004-09-01

60

Methane oxidation activity and bacterial community composition in a simulated landfill cover soil is influenced by the growth of Chenopodium album L  

Microsoft Academic Search

Oxygen availability in landfill cover soil is a major limitation to the growth and activity of methanotrophs as methane oxidation is an aerobic microbial process. Plants tolerant to high concentrations of landfill gas (LFG) may play an important role in improving methane oxidation within landfill cover soil and reducing emission of methane, a greenhouse gas, from it. In this study,

Yunlong Wang; Weixiang Wu; Ying Ding; Wei Liu; Anton Perera; Yingxu Chen; Medha Devare

2008-01-01

61

[Effects of methane stress on oxidation rates and microbial community structures in different landfill cover soils].  

PubMed

As compared with the ordinary landfill cover material, clay soil, the effect of methane stress on oxidation rate and microbial community structure was investigated in waste soil (material from biologically treated municipal solid waste). The results showed that the moisture content of the clay soil was low, due to the low water retaining capacity. As environmental temperature and rainfall changed, the clay soil caked and inhibited methanotrophs growth. However, with a high organic matter, water-holding capacity and porosity, the waste soil provided a favor condition for methanotrophs growth and propagation. After exposure to methane flow for 120 days, methane oxidation potential in the middle and bottom layers of the waste soil column increased to 11.25-13.48 micromol/(g x h), which was 10.4-24.5 times higher than that in clay soil column. The topsoils were both found to be dried and inhibit methane oxidation. Methane oxidation (removal) efficiency by the waste soil column reached 48.3% at the end of the experiment, which was 5-6 times higher than that by the clay soil column. The amounts of the phospholipid fatty acid (PLFA) biomarks 16:1 omega 8c and 18:1 omega 8c for Type I and II methanotrophs, respectively, showed that a strong linear relationship was observed between methane oxidation potential and PLFA 18:1 omega 8c content in soil samples. PMID:19256403

He, Ruo; Jiang, Chen-jing; Wang, Jing; Gao, Qing-jun; Shen, Dong-sheng

2008-12-01

62

Degradation of C2-C15 volatile organic compounds in a landfill cover soil.  

PubMed

The composition of non-methane volatile organic compounds (hereafter VOCs) in i) the cover soil, at depths of 30, 50 and 70 cm, and ii) gas recovery wells from Case Passerini landfill site, (Florence, Italy) was determined by GC-MS. The study, based on the analysis of interstitial gases sampled along vertical profiles within the cover soil, was aimed to investigate the VOC behaviour as biogas transits from a reducing to a relatively more oxidizing environment. A total of 48 and 63 different VOCs were identified in the soil and well gases, respectively. Aromatics represent the dominant group (71.5% of total VOC) in soil gases, followed by alkanes (6.8%), ketones (5.7%), organic acids (5.2%), aldehydes (3.0%), esters (2.6%), halogenated compounds (2.1%) and terpenes (1.3%). Cyclics, heterocyclics, S-bearing compounds and phenols are cover soil shows significant variations: alkanes, aromatics and cyclics decrease at decreasing depth, whereas an inverse trend is displayed by the O-bearing species. Total VOC and CH(4) concentrations at a depth of 30 cm in the soil are comparable, inferring that microbial activity is likely affecting VOCs at a very minor extent with respect to CH(4). According to these considerations, to assess the biogas emission impact, usually carried out on the sole basis of CO(2) and CH(4) emission rates, the physical-chemical behaviour of VOCs in the cover soil, regulating the discharge of these highly contaminant compounds in ambient air, has to be taken into account. The soil vertical distribution of these species can be used to better evaluate the efficiency of oxidative capability of intermediate and final covers. PMID:19446310

Tassi, Franco; Montegrossi, Giordano; Vaselli, Orlando; Liccioli, Caterina; Moretti, Sandro; Nisi, Barbara

2009-07-15

63

Inhibition of methane oxidation by volatile sulfur compounds (CH3SH and CS2) in landfill cover soils.  

PubMed

Methanethiol and carbon disulphide were investigated for their ability to inhibit methane oxidation in two landfill cover soils. Methanethiol was found to be a competitive inhibitor, and at concentrations occurring in landfills, both these VSCs (volatile sulfur compounds) had inhibitory effects on the methane oxidation rates. Analysis of the phospholipid fatty acid contents in the soils indicated that type I-methanotrophs were more affected than type II. These effects of VSCs on methane oxidation are likely to have implications both for the establishment and the selectivity of a methane oxidizing microflora in landfills. PMID:11720266

Börjesson, G

2001-08-01

64

Modelling of stable isotope fractionation by methane oxidation and diffusion in landfill cover soils  

SciTech Connect

A technique to measure biological methane oxidation in landfill cover soils that is gaining increased interest is the measurement of stable isotope fractionation in the methane. Usually to quantify methane oxidation, only fractionation by oxidation is taken into account. Recently it was shown that neglecting the isotope fractionation by diffusion results in underestimation of the methane oxidation. In this study a simulation model was developed that describes gas transport and methane oxidation in landfill cover soils. The model distinguishes between {sup 12}CH{sub 4}, {sup 13}CH{sub 4}, and {sup 12}CH{sub 3}D explicitly, and includes isotope fractionation by diffusion and oxidation. To evaluate the model, the simulations were compared with column experiments from previous studies. The predicted concentration profiles and isotopic profiles match the measured ones very well, with a root mean square deviation (RMSD) of 1.7 vol% in the concentration and a RMSD of 0.8 per mille in the {delta}{sup 13}C value, with {delta}{sup 13}C the relative {sup 13}C abundance as compared to an international standard. Overall, the comparison shows that a model-based isotope approach for the determination of methane oxidation efficiencies is feasible and superior to existing isotope methods.

Mahieu, Koenraad [Laboratory of Applied Physical Chemistry (ISOFYS), Ghent University, Coupure links 653, B-9000 Ghent (Belgium); Department of Applied Mathematics, Biometrics and Process Control (BIOMATH), Ghent University, Coupure links 653, B-9000 Ghent (Belgium)], E-mail: Koenraad.mahieu@lid.kviv.be; De Visscher, Alex [Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, T2N 1N4 (Canada); Vanrolleghem, Peter A. [Department of Applied Mathematics, Biometrics and Process Control (BIOMATH), Ghent University, Coupure links 653, B-9000 Ghent (Belgium); Department of Civil Engineering (modelEAU), Universite Laval, Pavillon Pouliot, Quebec, G1K 7P4 (Canada); Van Cleemput, Oswald [Laboratory of Applied Physical Chemistry (ISOFYS), Ghent University, Coupure links 653, B-9000 Ghent (Belgium)

2008-07-01

65

Modelling of stable isotope fractionation by methane oxidation and diffusion in landfill cover soils.  

PubMed

A technique to measure biological methane oxidation in landfill cover soils that is gaining increased interest is the measurement of stable isotope fractionation in the methane. Usually to quantify methane oxidation, only fractionation by oxidation is taken into account. Recently it was shown that neglecting the isotope fractionation by diffusion results in underestimation of the methane oxidation. In this study a simulation model was developed that describes gas transport and methane oxidation in landfill cover soils. The model distinguishes between 12CH4, 13CH4, and 12CH3D explicitly, and includes isotope fractionation by diffusion and oxidation. To evaluate the model, the simulations were compared with column experiments from previous studies. The predicted concentration profiles and isotopic profiles match the measured ones very well, with a root mean square deviation (RMSD) of 1.7 vol% in the concentration and a RMSD of 0.8 per thousand in the delta13C value, with delta13C the relative 13C abundance as compared to an international standard. Overall, the comparison shows that a model-based isotope approach for the determination of methane oxidation efficiencies is feasible and superior to existing isotope methods. PMID:17825548

Mahieu, Koenraad; De Visscher, Alex; Vanrolleghem, Peter A; Van Cleemput, Oswald

2008-01-01

66

Environmental factors influencing attenuation of methane and hydrochlorofluorocarbons in landfill cover soils.  

PubMed

The influence of different environmental factors on methane oxidation and degradation of hydrochlorofluorocarbons (HCFCs) was investigated in microcosms containing soil sampled at Skellingsted Landfill, Denmark. The soil showed a high capacity for methane oxidation resulting in a maximum oxidation rate of 104 microg CH4 g(-1) h(-1) and a low affinity of methane with a half-saturation constant of 2.0% v/v. The hydrochlorofluorocarbons HCFC-21 (dichlorofluoromethane) and HCFC-22 (chlorodifluoromethane) were rapidly oxidized and the oxidation occurred in parallel with the oxidation of methane. The maximal HCFC oxidation rates were 0.95 and 0.68 microg g(-1) h(-1) for HCFC-21 and HCFC-22, respectively. Increasing concentrations of HCFCs resulted in decreased methane oxidation rates. However, compared with typical concentrations in landfill gas, relatively high HCFC concentrations were needed to obtain a significant inhibition of methane oxidation. In general, the environmental factors studied influenced the degradation of HCFCs in almost the same way as they influenced methane oxidation. Temperature had a strong influence on the methanotrophic activity giving high Q10 values of 3.4 to 4.1 over the temperature range of 2 to 25 degrees C. Temperature optimum was around 30 degrees C; however, oxidation occurred at temperatures as low as 2 degrees C. A moisture content of 25% w/w yielded the maximum oxidation rate as it allowed good gas transport together with sufficient microbial activity. The optimum pH was around neutrality (pH = 6.5-7.5) showing that the methanotrophs were optimally adapted to the in situ pH, which was 6.9. Copper showed no inhibitory effect when added in relatively high concentrations (up to 60 mg kg(-1)), most likely due to sorption of copper ions to soil particles. At higher copper concentrations the oxidation rates decreased. The oxidation rates for methane, HCFC-21, and HCFC-22 were unaltered in ammonium-amended soil up to 14 mg kg(-1). Higher ammonium concentrations inhibited the oxidation process. The most important parameters controlling oxidation in landfill cover soil were found to be temperature, soil moisture, and methane and oxygen supply. PMID:14964360

Scheutz, Charlotte; Kjeldsen, Peter

2004-01-01

67

Methane oxidation in landfill cover soils, is a 10% default value reasonable?  

PubMed

We reviewed literature results from 42 determinations of the fraction of methane oxidized and 30 determinations of methane oxidation rate in a variety of soil types and landfill covers. Both column measurements and in situ field measurements were included. The means for the fraction of methane oxidized on transit across the soil covers ranged from 22 to 55% from clayey to sandy material. Mean values for oxidation rate ranged from 3.7 to 6.4 mol m(-2) d(-1) (52-102 g m(-2) d(-1)) for the different soil types. The overall mean fraction oxidized across all studies was 36% with a standard error of 6%. The overall mean oxidation rate across all studies was 4.5 mol m(-2) d(-1) +/- 1.0 (72 +/- 16 g m(-2)d(-1)). For the subset of 15 studies conducted over an annual cycle the fraction of methane oxidized ranged from 11 to 89% with a mean value of 35 +/- 6%, nearly identical to the overall mean. Nine of these studies were conducted in north Florida at 30 degrees N latitude and had a fraction oxidized of 27 +/- 4%. Five studies were conducted in northern Europe ( approximately 50-55 degrees N) and exhibited an average of 54 +/- 14%. One study, conducted in New Hampshire, had a value of 10%. The results indicate that the fraction of methane oxidized in landfill greater than the default value of 10%. Of the 42 determinations of methane oxidation reported, only four report values of 10% or less. PMID:19244486

Chanton, Jeffrey P; Powelson, David K; Green, Roger B

2009-01-01

68

Gas movement through fractured landfill cover materials  

Microsoft Academic Search

Bidirectional gas movement through fractured landfill cover materials is being studied at the Mallard North Landfill in DuPage County, Illinois. Vertical pressure and concentration gradients were monitored during changing meteorological and soil moisture conditions. Nests of probes for direct observation of subsurface soil gas pressures were installed in the top of the refuse and at depths of 1.2 m and

J. E. Bogner; C. A. Moore

1986-01-01

69

Characterization of methane oxidation by a methanotroph isolated from a landfill cover soil, South Korea.  

PubMed

A methane-oxidizing bacterium was isolated from the enriched culture of a landfill cover soil. The closest relative of the isolate, designated M6, is Methylocystis sp. Based on a kinetic analysis, the maximum specific methane oxidation rate and saturation constant were 4.93 mmol·g--dry cell weight--1·h?¹ and 23 microM, respectively. This was the first time a kinetic analysis was performed using pure methanotrophic culture. The methane oxidation by M6 was investigated in the presence of aromatic (m- and p-xylene and ethylbenzene) or sulfur (hydrogen sulfide, dimethyl sulfide, methanthiol) compounds. The methane oxidation was inhibited by the presence of aromatic or sulfur compounds. PMID:21791963

Lee, Eun-Hee; Yi, Taewoo; Moon, Kyung-Eun; Park, Hyunjung; Ryu, Hee Wook; Cho, Kyung-Suk

2011-07-01

70

Capacity for biodegradation of CFCs and HCFCs in a methane oxidative counter-gradient laboratory system simulating landfill soil covers.  

PubMed

The attenuation of methane and four chlorofluorocarbons was investigated in a dynamic methane and oxygen counter-gradient system simulating a landfill soil cover. Soil was sampled at Skellingsted Landfill, Denmark. The soil columns showed a high capacity of methane oxidation with oxidation rates of 210 g m(-2) d(-1) corresponding to a removal efficiency of 81%. CFC-11 and to a lesser extent also CFC-12 were degraded in the active soil columns. The average removal efficiency was 90% and 30% for CFC-11 and CFC-12, respectively. Soil gas concentration profiles indicated that the removal was due to anaerobic degradation, which was verified in anaerobic batch experiments where CFC-11 was rapidly degraded. HCFC-21 and HCFC-22 were also degraded in active soil columns (61% and 41%, respectively), but compared to the CFCs, the degradation was located in the upper oxic part of the column with overlapping gradients of methane and oxygen. High oxidation rates of methane and HCFCs were obtained in soil microcosms incubated with methane. When increasing the column inlet flow, the oxidation zone was moved upward in the column, and the removal efficiency of methane and HCFCs decreased. The removal of CFCs was, however, less affected since the anaerobic zone expanded with increasing inlet flow rates. This study demonstrates the complexity of landfill soil cover systems and shows that both anaerobic and aerobic bacteria may play a very important role in reducing the emission of not only methane but also trace components into the atmosphere. PMID:14655700

Scheutz, Charlotte; Kjeldsen, Peter

2003-11-15

71

Interaction and independence on methane oxidation of landfill cover soil among three impact factors: water, oxygen and ammonium  

Microsoft Academic Search

To understand the influence patterns and interactions of three important environmental factors, i.e. soil water content, oxygen\\u000a concentration, and ammonium addition, on methane oxidation, the soils from landfill cover layers were incubated under full\\u000a factorial parameter settings. In addition to the methane oxidation rate, the quantities and community structures of methanotrophs\\u000a were analyzed to determine the methane oxidation capacity of

Pinjing He; Na Yang; Wenjuan Fang; Fan Lü; Liming Shao

2011-01-01

72

CH4/CO2 ratios indicate highly efficient methane oxidation by a pumice landfill cover-soil.  

PubMed

Landfills that generate too little biogas for economic energy recovery can potentially offset methane (CH(4)) emissions through biological oxidation by methanotrophic bacteria in cover soils. This study reports on the CH(4) oxidation efficiency of a 10-year old landfill cap comprising a volcanic pumice soil. Surface CH(4) and CO(2) fluxes were measured using field chambers during three sampling intervals over winter and summer. Methane fluxes were temporally and spatially variable (-0.36 to 3044 mgCH(4)m(-2)h(-1)); but were at least 15 times lower than typical literature CH(4) fluxes reported for older landfills in 45 of the 46 chambers tested. Exposure of soil from this landfill cover to variable CH(4) fluxes in laboratory microcosms revealed a very strong correlation between CH(4) oxidation efficiency and CH(4)/CO(2) ratios, confirming the utility of this relationship for approximating CH(4) oxidation efficiency. CH(4)/CO(2) ratios were applied to gas concentrations from the surface flux chambers and indicated a mean CH(4) oxidation efficiency of 72%. To examine CH(4) oxidation with soil depth, we collected 10 soil depth profiles at random locations across the landfill. Seven profiles exhibited CH(4) removal rates of 70-100% at depths <60 cm, supporting the high oxidation rates observed in the chambers. Based on a conservative 70% CH(4) oxidation efficiency occurring at the site, this cover soil is clearly offsetting far greater CH(4) quantities than the 10% default value currently adopted by the IPCC. PMID:23186636

Pratt, Chris; Walcroft, Adrian S; Deslippe, Julie; Tate, Kevin R

2013-02-01

73

Use of gas push-pull tests for the measurement of methane oxidation in different landfill cover soils.  

PubMed

In order to optimise methane oxidation in landfill cover soils, it is important to be able to accurately quantify the amount of methane oxidised. This research considers the gas push-pull test (GPPT) as a possible method to quantify oxidation rates in situ. During a GPPT, a gas mixture consisting of one or more reactive gases (e.g., CH(4), O(2)) and one or more conservative tracers (e.g., argon), is injected into the soil. Following this, the mixture of injected gas and soil air is extracted from the same location and periodically sampled. The kinetic parameters for the biological oxidation taking place in the soil can be derived from the differences in the breakthrough curves. The original method of Urmann et al. (2005) was optimised for application in landfill cover soils and modified to reduce the analytical effort required. Optimised parameters included the flow rate during the injection phase and the duration of the experiment. 50 GPPTs have been conducted at different landfills in Germany during different seasons. Generally, methane oxidation rates ranged between 0 and 150 g m(soil air)(-3)h(-1). At one location, rates up to 440 g m(soil air)(-3)h(-1) were measured under particularly favourable conditions. The method is simple in operation and does not require expensive equipment besides standard laboratory gas chromatographs. PMID:20971626

Streese-Kleeberg, Jan; Rachor, Ingke; Gebert, Julia; Stegmann, Rainer

2011-05-01

74

Atmospheric emissions and attenuation of non-methane organic compounds in cover soils at a French landfill.  

PubMed

In addition to methane (CH(4)) and carbon dioxide (CO(2)), landfill gas may contain more than 200 non-methane organic compounds (NMOCs) including C(2+)-alkanes, aromatics, and halogenated hydrocarbons. Although the trace components make up less than 1% v/v of typical landfill gas, they may exert a disproportionate environmental burden. The objective of this work was to study the dynamics of CH(4) and NMOCs in the landfill cover soils overlying two types of gas collection systems: a conventional gas collection system with vertical wells and an innovative horizontal gas collection layer consisting of permeable gravel with a geomembrane above it. The 47 NMOCs quantified in the landfill gas samples included primarily alkanes (C(2)-C(10)), alkenes (C(2)-C(4)), halogenated hydrocarbons (including (hydro)chlorofluorocarbons ((H)CFCs)), and aromatic hydrocarbons (BTEXs). In general, both CH(4) and NMOC fluxes were all very small with positive and negative fluxes. The highest percentages of positive fluxes in this study (considering all quantified species) were observed at the hotspots, located mainly along cell perimeters of the conventional cell. The capacity of the cover soil for NMOC oxidation was investigated in microcosms incubated with CH(4) and oxygen (O(2)). The cover soil showed a relatively high capacity for CH(4) oxidation and simultaneous co-oxidation of the halogenated aliphatic compounds, especially at the conventional cell. Fully substituted carbons (TeCM, PCE, CFC-11, CFC-12, CFC-113, HFC-134a, and HCFC-141b) were not degraded in the presence of CH(4) and O(2). Benzene and toluene were also degraded with relative high rates. This study demonstrates that landfill soil covers show a significant potential for CH(4) oxidation and co-oxidation of NMOCs. PMID:18032020

Scheutz, C; Bogner, J; Chanton, J P; Blake, D; Morcet, M; Aran, C; Kjeldsen, P

2008-01-01

75

Selenium in tissues of rats fed rutabagas grown on soil covering a coal fly ash landfill  

Microsoft Academic Search

Approximately 80 million tons of fly ash are produced by coalburning power plants in the United States each year. Most is disposed in landfills which are capped with a layer of soil from about 0.5 toi meter thick. There has been concern that crops planted or voluntarily growing over such areas may absorb toxic elements which could be ingested by

Gilbert S. Stoewsand; Judy L. Anderson; Leonard H. Weinstein; Joseph F. Osmeloski; Walter H. Gutenmann; Donald J. Lisk

1990-01-01

76

Comparison of Methods to Assess the Fate of Methane in a Landfill-Cover Soil  

Microsoft Academic Search

A substantial fraction of the greenhouse gas methane released into the atmosphere is produced in terrestrial environments such as wetlands, rice paddy fields, and landfills. However, the amount of methane that is emitted from these environments is often reduced by microbial methane oxidation, mediated by methanotrophic microorganisms. Methanotrophs are ubiquitous in soils and represent the largest biological sink for methane.

K. E. Gomez; M. H. Schroth; W. Eugster; P. Niklaus; P. Oester; J. Zeyer

2008-01-01

77

Use of gas push–pull tests for the measurement of methane oxidation in different landfill cover soils  

Microsoft Academic Search

In order to optimise methane oxidation in landfill cover soils, it is important to be able to accurately quantify the amount of methane oxidised. This research considers the gas push–pull test (GPPT) as a possible method to quantify oxidation rates in situ. During a GPPT, a gas mixture consisting of one or more reactive gases (e.g., CH4, O2) and one

Jan Streese-Kleeberg; Ingke Rachor; Julia Gebert; Rainer Stegmann

2011-01-01

78

Comparative oxidation and net emissions of methane and selected non-methane organic compounds in landfill cover soils.  

PubMed

The surface emissions of methane (CH4) and non-methane organic compounds (NMOCs) were determined at two different areas at a French landfill: a permanently covered and fully vegetated area (40 cm coarse sand + 80 cm of loam) and a temporarily covered area (40 cm of coarse sand). The 37 NMOCs quantified in the landfill gas samples included alkanes (C1-C10), alkenes (C1-C4), halogenated hydrocarbons (including (H)CFCs), and aromatic hydrocarbons. Both positive and negative CH4 fluxes ranging from -0.01 to 0.008 g m(-2) d(-1) were measured from the permanently covered cell. However, high spatial variation was observed, and a hot spot with a high flux (10 g m(-2) d(-1)) was identified. A higher CH4 emission occurred from the temporarily covered cell (CH4 flux of 49.9 g m(-2) d(-1)) as compared to the permanently covered cell. The NMOC fluxes from the permanently covered zone were all very small with both positive and negative fluxes in the order of 10(-7) to 10(-5) g m(-2) d(-1). Higher and mainly positive NMOC fluxes in the order of 10(-5) to 10(-4) g m(-2) d(-1) were obtained from the temporarily covered zone. The lower emission from the permanently covered and fully vegetated cell was attributable to the thicker soil layer, which functions as microbial habitat for methanotrophic bacteria. The NMOC oxidation capacity was investigated in soil microcosms incubated with CH4. Maximal oxidation rates for the halogenated aliphatic compounds varied between 0.06 and 8.56 microg (g of soil)(-1) d(-1). Fully substituted hydrocarbons (tetrachloromethane, perchloroethylene, CFC-11, CFC-12, and CFC-113) were not degraded in the presence of CH4 and O2. Benzene and toluene were rapidly degraded, giving very high maximal oxidation rates (28 and 39 microg (g of soil)(-1) d(-1)). On the basis of the emission measurements and the batch experiments conducted, a general pattern was observed between emissions and biodegradability of various NMOCs. The emissions mainly consisted of compounds that were not degradable or slowly degradable, while an uptake of easily degradable compounds was registered. As an example, perchloroethylene, trichloromethane, CFC-11, and CFC-12 were emitted, while atmospheric consumption of aromatic hydrocarbons and lower chlorinated hydrocarbons such as vinyl chloride, dichloromethane, and chloromethane was observed. This study demonstrates that landfill soil covers show a significant potential for CH4 oxidation and co-oxidation of NMOCs. Under certain conditions, landfills may even function as sinks for CH4 and selected NMOCs, like aromatic hydrocarbons and lower chlorinated compounds. PMID:14655701

Schuetz, Charlotte; Bogner, Jean; Chanton, Jeffrey; Blake, Donald; Morcet, Muriel; Kjeldsen, Peter

2003-11-15

79

Mathematical modeling of leakage through macropores in landfill cover liners  

Microsoft Academic Search

Estimating leakage through cover and bottom liners of a landfill is an important component of evaluation of the proposed landfill designs. Leakage through landfill liners is generally estimated using mathematical models. However, existing models consider leakage only through micropores in the soil components of landfill liners; impact of macropores, such as freeze-thaw and desiccation cracks, on leakage is not considered.^

Manoj Mishra

1996-01-01

80

Field-Scale Stable-Isotope Probing of Active Methanotrophs in a Landfill-Cover Soil  

NASA Astrophysics Data System (ADS)

The greenhouse gas methane (CH4) is an important contributor to global climate change. While its atmospheric concentration is increasing, a large portion of produced CH4 never reaches the atmosphere, but is consumed by aerobic methane-oxidizing bacteria (MOB). The latter are ubiquitous in soils and utilize CH4 as sole source of energy and carbon. Among other methods, MOB may be differentiated based on characteristic phospholipid fatty acids (PLFA). Stable-isotope probing (SIP) on PLFA has been widely applied to identify active members of MOB communities in laboratory incubation studies, but results are often difficult to extrapolate to the field. Thus, novel field-scale approaches are needed to link activity and identity of MOB in their natural environment. We present results of field experiments in which we combined PLFA-SIP with gas push-pull tests (GPPTs) to label active MOB at the field-scale while simultaneously quantifying CH4 oxidation activity. During a SIP-GPPT, a mixture of reactive (here 13CH4, O2) and non-reactive tracer gases (e.g., Ar, Ne, He) is injected into the soil at a location of interest. Thereafter, gas flow is reversed and the gas mixture diluted with soil air is extracted from the same location and sampled periodically. Rate constants for CH4 oxidation can be calculated by analyzing breakthrough curves of 13CH4 and a suitable non-reactive tracer gas. SIP-GPPTs were performed in a landfill-cover soil, and feasibility of this novel approach was tested at several locations along a gradient of MOB activity and soil temperature. Soil samples were collected before and after SIP-GPPTs, total PLFA were extracted, and incorporation of 13C in the polar lipid fraction was analyzed. Potential CH4 oxidation rates derived from SIP-GPPTs were similar to those derived from regular GPPTs (using unlabeled CH4) performed at the same locations prior to SIP-GPPTs, indicating that application of 13CH4 did not adversely affect bacterial CH4 oxidation rates. Rates calculated for different locations ranged from 0.2 to 52.8 mmol CH4 (L soil air)-1 d-1. PLFA analyses showed high levels of 13C incorporation into different 14C and 16C fatty acids (FA), typically found in Type I MOB, and 18C FAs, typical for Type II MOB. The amount of 13C incorporated into biomass clearly increased with increasing activity, and ?13C values of >1500 ‰ were observed for selected FAs at high-activity locations. In addition, the range of labeled FAs also changed with activity, and no Type II MOB specific FAs were labeled at the low-activity location. The novel SIP-GPPT approach was shown to be a valuable field-scale method to detect and identify active MOB over a wide range of activities.

Schroth, M. H.; Henneberger, R.; Chiri, E.

2012-12-01

81

Methane Oxidation in Landfill Cover Soils, is a 10% Default Value Reasonable?  

Microsoft Academic Search

We reviewed literature results from 42 determinations of the fraction of methane oxidized and 30 determinations of methane oxidation rate in a variety of soil types and landfi ll covers. Both column measurements and in situ fi eld measurements were included. Th e means for the fraction of methane oxidized on transit across the soil covers ranged from 22 to

Jeffrey P. Chanton; David K. Powelson; Roger B. Green

2009-01-01

82

Transport and Reaction Processes Affecting the Attenuation of Landfill Gas in Cover Soils  

Microsoft Academic Search

Methane and trace organic gases produced in landfi ll waste are partly oxidized in the top 40 cm of landfi ll cover soils under aerobic conditions. Th e balance between the oxidation of landfi ll gases and the ingress of atmospheric oxygen into the soil cover determines the attenuation of emissions of methane, chlorofl uorocarbons, and hydrochlorofl uorocarbons to the

S. Molins; K. U. Mayer; C. Scheutz; P. Kjeldsen

2008-01-01

83

Capacity for Methane Oxidation in Landfill Cover Soils Measured in Laboratory-Scale Soil Microcosms  

Microsoft Academic Search

phiccapacity(10.4molofCH4 zm 22 zday 21 ),thegreatestyetreportedintheliterature.VerticalprofilesofO2, CH4, and methanotrophic potential in the soils were determined at steady state. Methane oxidation potentials weregreatestwheretheverticalprofilesofO2andCH4overlapped.Asignificantincreaseintheorganicmatter content of the soil, presumably derived from methanotroph biomass, occurred where CH4 oxidation was greatest. Methane oxidation kinetics showed that a soil community with a low methanotrophic capacity (Vmax of 258 nmol zg of soil 21 zh 21

DAVID KIGHTLEY; DAVID B. NEDWELL; ANDMICHAEL COOPER

1995-01-01

84

Capacity for methane oxidation in landfill cover soils measured in laboratory-scale soil microcosms.  

PubMed

Laboratory-scale soil microcosms containing different soils were permeated with CH(inf4) for up to 6 months to investigate their capacity to develop a methanotrophic community. Methane emissions were monitored continuously until steady states were established. The porous, coarse sand soil developed the greatest methanotrophic capacity (10.4 mol of CH(inf4) (middot) m(sup-2) (middot) day(sup-1)), the greatest yet reported in the literature. Vertical profiles of O(inf2), CH(inf4), and methanotrophic potential in the soils were determined at steady state. Methane oxidation potentials were greatest where the vertical profiles of O(inf2) and CH(inf4) overlapped. A significant increase in the organic matter content of the soil, presumably derived from methanotroph biomass, occurred where CH(inf4) oxidation was greatest. Methane oxidation kinetics showed that a soil community with a low methanotrophic capacity (V(infmax) of 258 nmol (middot) g of soil(sup-1) (middot) h(sup-1)) but relatively high affinity (k(infapp) of 1.6 (mu)M) remained in N(inf2)-purged control microcosms, even after 6 months without CH(inf4). We attribute this to a facultative, possibly mixotrophic, methanotrophic microbial community. When purged with CH(inf4), a different methanotrophic community developed which had a lower affinity (k(infapp) of 31.7 (mu)M) for CH(inf4) but a greater capacity (V(infmax) of 998 nmol (middot) g of soil(sup-1) (middot) h(sup-1)) for CH(inf4) oxidation, reflecting the enrichment of an active high-capacity methanotrophic community. Compared with the unamended control soil, amendment of the coarse sand with sewage sludge enhanced CH(inf4) oxidation capacity by 26%; K(inf2)HPO(inf4) amendment had no significant effect, while amendment with NH(inf4)NO(inf3) reduced the CH(inf4) oxidation capacity by 64%. In vitro experiments suggested that NH(inf4)NO(inf3) additions (10 and 71 (mu)mol (middot) g of soil(sup-1)) inhibited CH(inf4) oxidation by a nonspecific ionic effect rather than by specific inhibition by NH(inf4)(sup+). PMID:16534930

Kightley, D; Nedwell, D B; Cooper, M

1995-02-01

85

Capacity for Methane Oxidation in Landfill Cover Soils Measured in Laboratory-Scale Soil Microcosms  

PubMed Central

Laboratory-scale soil microcosms containing different soils were permeated with CH(inf4) for up to 6 months to investigate their capacity to develop a methanotrophic community. Methane emissions were monitored continuously until steady states were established. The porous, coarse sand soil developed the greatest methanotrophic capacity (10.4 mol of CH(inf4) (middot) m(sup-2) (middot) day(sup-1)), the greatest yet reported in the literature. Vertical profiles of O(inf2), CH(inf4), and methanotrophic potential in the soils were determined at steady state. Methane oxidation potentials were greatest where the vertical profiles of O(inf2) and CH(inf4) overlapped. A significant increase in the organic matter content of the soil, presumably derived from methanotroph biomass, occurred where CH(inf4) oxidation was greatest. Methane oxidation kinetics showed that a soil community with a low methanotrophic capacity (V(infmax) of 258 nmol (middot) g of soil(sup-1) (middot) h(sup-1)) but relatively high affinity (k(infapp) of 1.6 (mu)M) remained in N(inf2)-purged control microcosms, even after 6 months without CH(inf4). We attribute this to a facultative, possibly mixotrophic, methanotrophic microbial community. When purged with CH(inf4), a different methanotrophic community developed which had a lower affinity (k(infapp) of 31.7 (mu)M) for CH(inf4) but a greater capacity (V(infmax) of 998 nmol (middot) g of soil(sup-1) (middot) h(sup-1)) for CH(inf4) oxidation, reflecting the enrichment of an active high-capacity methanotrophic community. Compared with the unamended control soil, amendment of the coarse sand with sewage sludge enhanced CH(inf4) oxidation capacity by 26%; K(inf2)HPO(inf4) amendment had no significant effect, while amendment with NH(inf4)NO(inf3) reduced the CH(inf4) oxidation capacity by 64%. In vitro experiments suggested that NH(inf4)NO(inf3) additions (10 and 71 (mu)mol (middot) g of soil(sup-1)) inhibited CH(inf4) oxidation by a nonspecific ionic effect rather than by specific inhibition by NH(inf4)(sup+).

Kightley, D.; Nedwell, D. B.; Cooper, M.

1995-01-01

86

The effects of daily cover soils on shear strength of municipal solid waste in bioreactor landfills  

Microsoft Academic Search

Bioreactor landfills are operated to enhance refuse decomposition, gas production, and waste stabilization. The major aspect of bioreactor landfill operation is the recirculation of collected leachate back through the refuse mass. Due to the accelerated decomposition and settlement of solid waste, bioreactor landfills are gaining popularity as an alternative to the conventional landfill. The addition or recirculation of leachate to

Mohamed A. Haque

2009-01-01

87

Methane oxidation in a neutral landfill cover soil: Influence of moisture content, temperature, and nitrogen-turnover  

SciTech Connect

Well-managed, aerated cover soils can have a mitigating effect on methane emission from landfills. The influence of moisture content, soil temperature, and N on the methane uptake capacity of a neutral landfill cover soil was examined. A soil moisture content of 15% w/w gave the maximum CH{sub 4} oxidation rate (2.36 ng CH{sub 4}{sup -1}g{sup -1} soil). When wetter, CH{sub 4} consumption was slower (e.g., 1.6 ng CH{sub 4} h{sup -1} g {sup -1} at 30% w/w) because of a limited gas diffusion. At lower soil moisture, microbial activity was reduced and consequently the oxidation capacity decreased (e.g., 0.84 ng CH{sub 4} {sup -1} g{sup -1} at 5% w/w). Optimum temperature was between 25 and 30{degrees}C. The calculated activation energy of the CH{sub 4} oxidation was 56.5 kj K{sup -1} mol{sup -1}. After NH4{sub 4}{sup +} addition, a negative linear correlation was found between the methane oxidation rate and the nitrous oxide flux (R{sup 2} = 0.96 Y1 = 2.7 - 0.44 x Y2). Addition of NO{sub 3}{sup -} had no significant effect on CH{sub 4} oxidation. The effect of organic residue amendments depended on their C/N ratios. Crop residues with a high C/N ratio (wheat [Triticum sativum L.] and maize [Zea mays L.] straw) stimulated N-immobilization and did not affect the methane-oxidizing capacity. On the other hand, addition of crop residues with low C/N ratios (potato [Solanum tuberosum L.] and sugar beet [Beta vulgaris cv. Altissima] leaves) stimulated N-mineralization, resulting in a strong inhibition of the methane oxidation. 38 refs., 4 figs., 2 tabs.

Boeckx, P.; Van Cleemput, O. [Univ. of Ghent (Belgium)

1996-01-01

88

Field-scale labelling and activity quantification of methane-oxidizing bacteria in a landfill-cover soil.  

PubMed

Aerobic methane-oxidizing bacteria (MOB) play an important role in soils, mitigating emissions of the greenhouse gas methane (CH(4)) to the atmosphere. Here, we combined stable isotope probing on MOB-specific phospholipid fatty acids (PLFA-SIP) with field-based gas push-pull tests (GPPTs). This novel approach (SIP-GPPT) was tested in a landfill-cover soil at four locations with different MOB activity. Potential oxidation rates derived from regular- and SIP-GPPTs agreed well and ranged from 0.2 to 52.8 mmol CH(4) (L soil air)(-1) day(-1). PLFA profiles of soil extracts mainly contained C(14) to C(18) fatty acids (FAs), with a dominance of C(16) FAs. Uptake of (13) C into MOB biomass during SIP-GPPTs was clearly indicated by increased ?(13)C values (up to c. 1500‰) of MOB-characteristic FAs. In addition, (13)C incorporation increased with CH(4) oxidation rates. In general, FAs C(14:0) , C(16:1?8), C(16:1?7) and C(16:1?6) (type I MOB) showed highest (13)C incorporation, while substantial (13)C incorporation into FAs C(18:1?8) and C(18:1?7) (type II MOB) was only observed at high-activity locations. Our findings demonstrate the applicability of the SIP-GPPT approach for in situ quantification of potential CH(4) oxidation rates and simultaneous labelling of active MOB, suggesting a dominance of type I MOB over type II MOB in the CH(4)-oxidizing community in this landfill-cover soil. PMID:22928887

Henneberger, Ruth; Chiri, Eleonora; Blees, Jan; Niemann, Helge; Lehmann, Moritz F; Schroth, Martin H

2013-02-01

89

Alternative Landfill Cover. Innovative Technology Summary Report  

SciTech Connect

The primary purpose of an engineered cover is to isolate the underlying waste. A key element to isolating the wastes from the environment, engineered covers should minimize or prevent water from infiltrating into the landfill and coming into contact with the waste, thereby minimizing leachate generation. The U.S. EPA construction guidelines for soil hydraulic barriers specify that the soil moisture content and compactive effort may be increased to ensure that the barrier achieves a specified permeability of 1 x 10{sup {minus}7} cm/sec. However, constructing a soil barrier with high moisture content makes the soil more difficult to work and increases the required compactive effort to achieve the specified density, ultimately increasing the construction cost of the barrier. Alternative landfill cover designs rely on soil physical properties, hydraulic characteristics, and vegetation requirements to lower the flux rate of water through the cover. They can achieve greater reliability than the prescriptive RCRA Subtitle C design, especially under arid or semi-arid environmental conditions. With an alternative cover design, compacted soil barriers can be constructed with a soil moisture content that makes placement and compaction of the soil easier and less expensive. Under these conditions, the soil barrier has more capacity to absorb and control moisture within it, thereby enhancing the reliability of the barrier. This document contains information on the above-mentioned technology, including description, applicability, cost, and performance, data.

NONE

2000-12-01

90

Instrumentation for continuous monitoring of meteorological variables and soil gas pressure in landfill cover  

SciTech Connect

To examine changes in soil gas pressure relative to changes in atmospheric pressure and other meteorological variables, weather station sensors and electronic pressure transducers were interfaced with an RCA COSMAC microcomputer. The microcomputer control permitted simultaneous acquisition of pressure and meteorological data on cassette tape. Because the RCA unit uses CMOS circuitry, it can be battery operated, and is therefore well suited for collecting data at remote locations on landfills. A tape I/O board, an A/D converter board and two custom boards were required additions to the basic CDP18S601 board for this application. Meteorological data, including wind speed, wind direction, air temperature, precipitation, and solar radiation, were monitored using a Climatronics EWS system. Barometric pressure and soil gas pressures on subsurface probes were monitored using electronic pressure transducers with a 10 to 20 psia range. Cassette tape output was dumped directly to WYLBUR files on the Argonne National Laboratory (ANL) IBM 3033 mainframe for subsequent data analysis.

Moore, C.; Vogt, M.; Bogner, J.

1986-09-01

91

Use of stable isotopes to determine methane oxidation in landfill cover soils  

Microsoft Academic Search

The mean isotopic composition of CH4 emitted from six New England (United States) landfills was 13C and D enriched (-48.1 to -50.40\\/00 and -273 to -2810\\/00) relative to anoxic zone landfill CH4 (mean values of -55.9 to -56.20\\/00 and -296 to -3000\\/00) owing to the oxidation of methane as it was transported from the landfill to the atmosphere through the

K. Liptay; J. Chanton; P. Czepiel; B. Mosher

1998-01-01

92

Stable isotope pulse-chasing and compound specific stable carbon isotope analysis of phospholipid fatty acids to assess methane oxidizing bacterial populations in landfill cover soils.  

PubMed

The oxidation of methane by bacteria residing in soils constitutes an important terrestrial methane sink. These bacteria are particularly abundant in the covering soils of landfill caps due to the supply of high concentrations of methane from the landfill below. Only about 0.1% of soil bacteria are amenable to available methods of culturing, resulting in the need for a method of in situ analysis. A combination of phospholipid fatty acid (PLFA) analysis and stable isotopic labeling has been employed in this investigation as a means of cultivation-independent bacterial analysis. Soil samples taken from the profiles of two landfill caps, one of clay and one of sand, were incubated with 13C-labeled methane. PLFAs were analyzed by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) in order to determine their 13C content, from which the PLFA distribution of the methane-oxidizing bacteria was calculated. Neither landfill cap supported communities of bacteria capable of oxidizing ambient levels of methane but only those elevated levels that are usually attributable to landfills. The clay-capped landfill profile exhibited a change in the methane-oxidizing bacterial community with depth, whereas the sand-capped landfill site displayed a mixture of both type I and II methanotrophs throughout the profile. Two additional samples, taken from sites where methane production was evident, were particularly dominated by type II methanotrophic bacteria. PMID:15046336

Crossman, Zoë M; Abraham, Faye; Evershed, Richard P

2004-03-01

93

Field Water Balance of Landfill Final Covers  

SciTech Connect

Landfill covers are critical to waste containment, yet field performance of specific cover designs has not been well documented and seldom been compared in side-by-side testing. A study was conducted to asses the ability of landfill final covers to control percolation into underlying waste. Conventional covers employing resistive barriers as well as alternative covers relying on water-storage principles were monitored in large (10 x 20), instrumented drainage lysimeters over a range of climates at field sites in the United States. Surface runoff was a small fraction of the water balance (0-10%, 4% on average) and was nearly insensitive to the cover slope, cover design, or climate. Lateral drainage from internal drainage layers was also a small fraction of the water balance (0-5%, 2.0% on average). Average percolation rates for the conventional covers with composite barriers (geomembrane over fine soil) typically were less than 12 mm/yr (1.4% of precipitation) at humid locations and 1.5 mm/yr (0.4% of precipitation) at arid, semiarid, and subhumid locations. Average percolation rates for conventional covers with soil barriers in humid climates were between 52 and 195 mm/yr (6-17% of precipitation), probably due to preferential flow through defects in the soil barriers. Average percolation rates for alternative covers ranged between 33 and 160 mm/yr (6 and 18% if precipitation) in humid climates and generally less than 2.2 mm/yr (0.4% of precipitation) in arid, semiarid, and subhumid climates. One half (five) of the alternative covers in arid, semiarid, and subhumid climates transmitted less than 0.1 mm of percolation, but two transmitted much more percolation (26.8 and 52 mm) than anticipated during design. The data collected support conclusions from other studies that detailed, site-specific design procedures are very important for successful performance of alternative landfill covers.

Albright, William H.; Benson, Craig H.; Gee, Glendon W.; Roesler, Arthur C.; Abichou, Tarek; Apiwantragoon, Preecha; Lyles, Bradley F.; Rock, S A.

2004-11-15

94

Ammonium-dependent regulation of aerobic methane-consuming bacteria in landfill cover soil by leachate irrigation.  

PubMed

The impacts of landfill leachate irrigation on methane oxidation activities and methane-consuming bacteria populations were studied by incubation of landfill cover soils with leachate and (NH4)2SO4 solution at different ammonium concentrations. The community structures and abundances of methane-oxidizing bacteria (MOB) and ammonia-oxidizing bacteria (AOB) were examined by PCR-DGGE and real-time PCR. Compared with the pure (NH4)2SO4 solution, leachate addition was found to have a positive effect on methane oxidation activity. In terms of the irrigation amount, ammonium in leachate was responsible for the actual inhibition of leachate. The extent of inhibitory effect mainly depended on its ammonium concentration. The suppression of the predominant methane-consuming bacteria, type I MOB, was responsible for the decreased methane oxidation activity by ammonium inhibition. Methane-consuming bacteria responded diversely in abundance to ammonium. The abundance of type I MOB decreased by fivefold; type II MOB showed stimulation response of fivefold magnification upon the first addition but lessened to be lower than the original level after the second addition; the amount of AOB was stimulated to increase for 20-30 times gradually. Accumulated nitrate from nitrification strengthened the ammonium inhibition on type I and type II MOB, as a result, repetitive irrigation was unfavorable for methane oxidation. PMID:22894107

Lü, Fan; He, Pinjing; Guo, Min; Yang, Na; Shao, Liming

2012-01-01

95

Effects of dry bulk density and particle size fraction on gas transport parameters in variably saturated landfill cover soil  

SciTech Connect

Highlights: > The effects of soil physical properties on gas transport parameters were investigated. > Higher values of D{sub p} and k{sub a} exhibited in the '+gravel' than the '-gravel' fraction at same soil-air content ({epsilon}). > Recent power law models for D{sub p} (WLR) and k{sub a} (RPL) were modified. > Model parameters were linearly related to easily measurable dry bulk density ({rho}{sub b}). - Abstract: Landfill sites are emerging in climate change scenarios as a significant source of greenhouse gases. The compacted final soil cover at landfill sites plays a vital role for the emission, fate and transport of landfill gases. This study investigated the effects of dry bulk density, {rho}{sub b}, and particle size fraction on the main soil-gas transport parameters - soil-gas diffusivity (D{sub p}/D{sub o}, ratio of gas diffusion coefficients in soil and free air) and air permeability (k{sub a}) - under variably-saturated moisture conditions. Soil samples were prepared by three different compaction methods (Standard and Modified Proctor compaction, and hand compaction) with resulting {rho}{sub b} values ranging from 1.40 to 2.10 g cm{sup -3}. Results showed that D{sub p} and k{sub a} values for the '+gravel' fraction (<35 mm) became larger than for the '-gravel' fraction (<2 mm) under variably-saturated conditions for a given soil-air content ({epsilon}), likely due to enhanced gas diffusion and advection through less tortuous, large-pore networks. The effect of dry bulk density on D{sub p} and k{sub a} was most pronounced for the '+gravel' fraction. Normalized ratios were introduced for all soil-gas parameters: (i) for gas diffusivity D{sub p}/D{sub f}, the ratio of measured D{sub p} to D{sub p} in total porosity (f), (ii) for air permeability k{sub a}/k{sub a,pF4.1}, the ratio of measured k{sub a} to k{sub a} at 1235 kPa matric potential (=pF 4.1), and (iii) for soil-air content, the ratio of soil-air content ({epsilon}) to total porosity (f) (air saturation). Based on the normalized parameters, predictive power-law models for D{sub p}({epsilon}/f) and k{sub a}({epsilon}/f) models were developed based on a single parameter (water blockage factor M for D{sub p} and P for k{sub a}). The water blockage factors, M and P, were found to be linearly correlated to {rho}{sub b} values, and the effects of dry bulk density on D{sub p} and k{sub a} for both '+gravel' and '-gravel' fractions were well accounted for by the new models.

Wickramarachchi, Praneeth, E-mail: praneeth1977@yahoo.co.uk [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Kawamoto, Ken; Hamamoto, Shoichiro [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Nagamori, Masanao [Center for Environmental Science in Saitama, 914 Kamitanadare, Kazo, Saitama 347-0115 (Japan); Moldrup, Per [Environmental Engineering Section, Dept. of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 57, DK-9000 Aalborg (Denmark); Komatsu, Toshiko [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan)

2011-12-15

96

Gas movement through fractured landfill cover materials  

SciTech Connect

Bidirectional gas movement through fractured landfill cover materials is being studied at the Mallard North Landfill in DuPage County, Illinois. Vertical pressure and concentration gradients were monitored during changing meteorological and soil moisture conditions. Nests of probes for direct observation of subsurface soil gas pressures were installed in the top of the refuse and at depths of 1.2 m and 0.6 m. Subsurface gas pressures, barometric pressure, wind speed, wind direction, solar radiation, air temperature, and precipitation were continuously monitored. A field gas chromatograph permitted frequent analysis of methane, carbon dioxide, nitrogen, and oxygen in soil gas samples from the various probes. Tensiometers provided information on soil moisture conditions. During dry weather, soil gas pressures at all depths equilibrated rapidly with barometric pressure and exhibited diurnal variations that were inversely proportional to diurnal temperature variations. When cover materials became saturated, changes in soil gas pressures sometimes lagged behind changes in atmospheric pressure by two to three hours. Soil gas concentrations generally exhibited relatively small short-term variations, but responded over the longer term to changing soil moisture conditions. Carbon-dioxide:methane ratios suggest that an important near-surface process is the activity of methane-oxidizing bacteria, which consume methane that might otherwise be available to a gas recovery system.

Bogner, J.E.; Moore, C.A.

1986-01-01

97

Filth flies associated with municipal solid waste and impact of delay in cover soil application on adult filth fly emergence in a sanitary landfill in Pulau Pinang, Malaysia.  

PubMed

Two types of municipal solid waste (MSW), newly arrived and 2 weeks old, were sampled from a sanitary landfill in Pulau Pinang, Malaysia at a fortnightly interval and kept under field conditions for 2 weeks. A total of 480 kg of each type of MSW was sampled to study species composition and impact of delays in cover soil applications on filth fly emergence. Out of 960 kg of MSW sampled, 9.2 ± 0.5 flies emerged per kilogram. Weekly adult fly emergence rates of newly arrived and 2-week-old waste did not differ significantly and MSW remained suitable for fly breeding for up to 1 month. Eight species of flies emerged from the MSW: namely, Musca domestica, Musca sorbens, Synthesiomyia nudiseta, Hydrotaea chalcogaster, Chrysomya megacephala, Lucilia cuprina, Hemipyrellia ligurriens and Sarcophaga sp. Newly arrived waste was determined to be the main source for M. domestica, C. megacephala and L. cuprina in the landfill owing to significantly higher mean emergence compared with 2-week-old waste. Musca sorbens was found in newly arrived waste but not in 2-week-old waste, suggesting that the species was able to survive transportation to landfill but unable to survive landfill conditions. Hemipyrellia ligurriens, H. chalcogaster and S. nudiseta were not imported into the landfill with MSW and pre-existing flies in and around the landfill itself may be their source. The results show that landfills can be a major source of fly breeding if cover soil or temporary cover is not applied daily or on a regular schedule. PMID:23302698

Nurita, A T; Hassan, A Abu

2013-06-01

98

Performance of landfill cover systems in cold climates  

Microsoft Academic Search

The function of cover systems is to prevent the infiltration of water into the landfill and to control the release of gases from the landfill. Previous studies of this problem have utilized small-scale soil samples, often compacted under conditions different to those used in the field. Although these tests have been invaluable in clarifying the problem of freeze-thaw, extending the

Jai-Young Lee

1994-01-01

99

Effect of substrate interaction on oxidation of methane and benzene in enriched microbial consortia from landfill cover soil.  

PubMed

The interaction of methane and benzene during oxidation in enriched methane-oxidizing consortium (MOC) and in benzene-oxidizing consortium (BOC) from landfill cover soil was characterized. Oxidation of both methane and benzene occurred in the MOC due to the coexistence of bacteria responsible for benzene oxidation, as well as methanotrophs, whereas in the BOC, only benzene was oxidized, not methane. Methane oxidation rates in the MOC were decreased with increasing benzene/methane ratio (mol/mol), indicating its methane oxidation was inhibited by the benzene coexistence. Benzene oxidation rates in the MOC, however, were increased with increasing benzene/methane ratio. The benzene oxidation in the BOC was not affected by the coexistence of methane or by the ratio of methane/benzene ratio (mol/mol). No effect of methane or benzene was found on the dynamics of functional genes, such as particulate methane monooxygenase and toluene monooxygenase, in association with oxidation of methane and benzene in the MOC and BOC. PMID:21847790

Lee, Eun-Hee; Park, Hyunjung; Cho, Kyung-Suk

2011-01-01

100

Mitigating CH? emissions in semi-aerobic landfills: impacts of operating conditions on abundance and community structure of methanotrophs in cover soils.  

PubMed

Methanotrophs are the most important sink of CH?, which is a more highly potent greenhouse gas than CO?. Methanotrophic abundance and community diversity in cover soils from two typical semi-aerobic landfills (SALs) in China were detected using real-time polymerase chain reaction (real-time-PCR) and denaturing gradient gel electrophoresis (DGGE) based on 16S rRNA genes, respectively. Real time-PCR showed that Type I methanotrophs ranged from 1.07 × 10? to 2.34 × 10? copies/g soil and that of Type II methanotrophs from 1.51 × 10? to 1.83 × 10? copies/g soil. The ratio of Type II to Type I methanotrophic copy numbers ranged from 5.61 to 21.89, indicating that Type II methanotrophs dominated in SAL. DGGE revealed that Type I methanotrophs responded more sensitively to the environment, changing as the community structure varied with different soil types and locations. Methylobacter, Methylosarcina, and Methylomicrobium for Type I, and Methylocystis for Type II were most prevalent in the SAL cover layer. Abundant interflow O? with high CH? concentration in SALs is the reason for the higher population density of methanotrophs and the higher enrichment of Type II methanotrophs compared with anaerobic landfills and other ecosystems, which proved a conclusion that increasing the oxygen supply in a landfill cover layer would greatly improve CH? mitigation. PMID:23711522

Li, Huai; Chi, Zi-Fang; Lu, Wen-Jing; Wang, Hong-Tao

2013-01-01

101

Instrumentation for continuous monitoring of meteorological variables and soil gas pressure in landfill cover  

Microsoft Academic Search

To examine changes in soil gas pressure relative to changes in atmospheric pressure and other meteorological variables, weather station sensors and electronic pressure transducers were interfaced with an RCA COSMAC microcomputer. The microcomputer control permitted simultaneous acquisition of pressure and meteorological data on cassette tape. Because the RCA unit uses CMOS circuitry, it can be battery operated, and is therefore

C. Moore; M. Vogt; J. Bogner

1986-01-01

102

Evaluation of potential inhibitors of methanogenesis and methane oxidation in a landfill cover soil  

Microsoft Academic Search

Biological methane (CH4) production is an anaerobic process, while CH4 consumption occurs predominantly under aerobic conditions; however, both processes can occur simultaneously in soil. Thus, field measurements of CH4 flux reflect the net result of both consumption and production reactions. Specific inhibitors of either CH4 consumption or production processes offer the opportunity for assessing the rates of these two processes

A. S. K. Chan; T. B. Parkin

2000-01-01

103

Seasonal variation in methane oxidation in a landfill cover soil as determined by an in situ stable isotope technique  

Microsoft Academic Search

Seasonal variations in the oxidation of methane during its transport across the soil cap of a landfill in Leon County, Florida, were determined in situ with a stable isotopic technique. The approach contrasted the delta13C values of emitted and anoxic zone CH4 and utilized measurements of the isotopic fractionation factor alpha, which varied inversely with temperature from 1.025 to 1.049.

Jeffrey Chanton; Karen Liptay

2000-01-01

104

16S rRNA based T-RFLP analysis of methane oxidising bacteria—Assessment, critical evaluation of methodology performance and application for landfill site cover soils  

Microsoft Academic Search

Methanotrophic bacteria have a ubiquitous distribution in the environment and play an important role in global climate warming by lowering methane emission into the atmosphere. Globally, landfill sites produce about 10% of the methane entering the atmosphere, and soils above landfill sites have been shown to contain methanotrophic populations with the highest methane oxidation capacity measured.Landfill site simulating lysimeters were

Nancy Stralis-Pavese; Levente Bodrossy; Thomas G. Reichenauer; Alexandra Weilharter; Angela Sessitsch

2006-01-01

105

Evaluation of the odour reduction potential of alternative cover materials at a commercial landfill  

Microsoft Academic Search

The availability of virgin soils and traditional landfill covers are not only costly and increasingly becoming scarce, but they also reduce the storage capacity of landfill. The problem can be overcome by the utilisation of certain suitable waste streams as alternative landfill covers. The objective of this study was to assess the suitability of Construction & Demolition fines (C&D), Commercial

P. J. Solan; V. A. Dodd; T. P. Curran

2010-01-01

106

Identification of active methanotrophs in a landfill cover soil through detection of expression of 16S rRNA and functional genes.  

PubMed

Active methanotrophs in a landfill soil were revealed by detecting the 16S rRNA of methanotrophs and the mRNA transcripts of key genes involved in methane oxidation. New 16S rRNA primers targeting type I and type II methanotrophs were designed and optimized for analysis by denaturing gradient gel electrophoresis. Direct extraction of RNA from soil enabled the analysis of the expression of the functional genes: mmoX, pmoA and mxaF, which encode subunits of soluble methane monooxygenase, particulate methane monooxygenase and methanol dehydrogenase respectively. The 16S rRNA polymerase chain reaction (PCR) primers for type I methanotrophs detected Methylomonas, Methylosarcina and Methylobacter sequences from both soil DNA and cDNA which was generated from RNA extracted directly from the landfill cover soil. The 16S rRNA primers for type II methanotrophs detected primarily Methylocella and some Methylocystis 16S rRNA genes. Phylogenetic analysis of mRNA recovered from the soil indicated that Methylobacter, Methylosarcina, Methylomonas, Methylocystis and Methylocella were actively expressing genes involved in methane and methanol oxidation. Transcripts of pmoA but not mmoX were readily detected by reverse transcription polymerase chain reaction (RT-PCR), indicating that particulate methane monooxygenase may be largely responsible for methane oxidation in situ. PMID:17922768

Chen, Yin; Dumont, Marc G; Cébron, Aurélie; Murrell, J Colin

2007-11-01

107

Effects of ammonia on methane oxidation in landfill cover materials.  

PubMed

The effects of ammonia (NH3) on CH4 attenuation in landfill cover materials consisting of landfill cover soil (LCS) and aged municipal solid waste (AMSW), at different CH4 concentrations, were investigated. The CH4 oxidation capacities of LCS and AMSW were found to be significantly affected by the CH4 concentration. The maximum oxidation rates for LCS and AMSW were obtained at CH4 concentrations of 5% and 20%(v/v), respectively, within 20 days. CH4 biological oxidation in AMSW was significantly inhibited by NH3 at low CH4 concentrations (5%, v/v) but highly stimulated at high levels (20% and 50%, v/v). Oxidation in LCS was stimulated by NH3 at all CH4 concentrations due to the higher conversion of the nitrogen in NH3 in AMSW than in LCS. NH3 increases CH4 oxidation in landfill cover materials. PMID:23832775

Long, Yu-Yang; Liao, Yan; Miao, Jing-Yu; Shen, Dong-Sheng

2014-01-01

108

Modeling of H(2)S migration through landfill cover materials.  

PubMed

The emission of H2S from landfills in the United States is an emergent problem because measured concentrations within the waste mass and in ambient air have been observed at potentially unsafe levels for on-site workers and at levels that can cause a nuisance and potentially deleterious health impacts to surrounding communities. Though recent research has provided data on H2S concentrations that may be observed at landfills, facility operators and landfill engineers have limited predictive tools to anticipate and plan for potentially harmful H2S emissions. A one-dimensional gas migration model was developed to assist engineers and practitioners better evaluate and predict potential emission levels of H2S based on four factors: concentration of H2S below the landfill surface (C0), advection velocity (v), H2S effective diffusion coefficient (D), and H2S adsorption coefficient of landfill cover soil (?). Model simulations indicated that H2S migration into the atmosphere can be mitigated by reducing H2S diffusion and advection or using alternative cover soils with a high H2S adsorption coefficient. Laboratory column experiments were conducted to investigate the effects of the four parameters on H2S migration in cover soils and to calculate the adsorption coefficient of different cover materials. The model was validated by comparing results with laboratory column experiments. Based on the results, the laboratory column provides an effective way to estimate the H2S adsorption coefficient, which can then be incorporated into the developed model to predict the depth of cover soil required to reduce emitted H2S concentrations below a desired level. PMID:24316799

Xu, Qiyong; Powell, Jon; Jain, Pradeep; Townsend, Timothy

2014-01-15

109

Methane oxidation in a landfill cover with capillary barrier  

Microsoft Academic Search

The methane oxidation potential of a landfill cover with capillary barrier was investigated in an experimental plant (4.8m×0.8m×2.1m). The cover soil consisted of two layers, a mixture of compost plus sand (0.3m) over a layer of loamy sand (0.9m). Four different climatic conditions (summer, winter, spring and fall) were simulated. In and outgoing fluxes were measured. Gas composition, temperature, humidity,

J. Berger; L. V. Fornés; C. Ott; J. Jager; B. Wawra; U. Zanke

2005-01-01

110

LOCATING LANDFILL LEAKS COVERED WITH WASTE  

Microsoft Academic Search

SUMMARY: A newly constructed single-lined geomembrane municipal solid waste (MSW) landfill cell developed leaks after two to five meters of waste were placed in the cell. The primary liner was initially leak tested using an electrical leak location method after the protective drainage soil was placed on the liner. All leaks that were located were repaired. Therefore, the reported leakage

P. COLUCCI; G. T. DARILEK; D. L. LAINE; A. BINLEY

111

Biotic landfill cover treatments for mitigating methane emissions.  

PubMed

Landfill methane (CH4) emissions have been cited as one of the anthropogenic gas releases that can and should be controlled to reduce global climate change. This article reviews recent research that identifies ways to enhance microbial consumption of the gas in the aerobic portion of a landfill cover. Use of these methods can augment CH4 emission reductions achieved by gas collection or provide a sole means to consume CH4 at small landfills that do not have active gas collection systems. Field studies indicate that high levels of CH4 removal can be achieved by optimizing natural soil microbial processes. Further, during biotic conversion, not all of the CH4 carbon is converted to carbon dioxide (CO2) gas and released to the atmosphere; some of it will be sequestered in microbial biomass. Because biotic covers can employ residuals from other municipal processes, financial benefits can also accrue from avoided costs for residuals disposal. PMID:12733810

Hilgeri, Helene; Humer, Marion

2003-05-01

112

GEOSYNTHETIC CLAY LINERS (GCLS) IN LANDFILL COVERS  

EPA Science Inventory

Low permeability, compacted clay linters are commonly required as a barrier to water infiltration in landfill covers. elatively new material, known as geosynthetic clay liner (GCL), has been proposed as an alternative to a compacted clay liner. CL has the practical advantages of ...

113

Evaluation of simultaneous biodegradation of methane and toluene in landfill covers.  

PubMed

The biodegradation of CH4 and toluene in landfill cover soil (LCS) and waste biocover soil (WBS) was investigated with a serial toluene concentration in the headspace of landfill cover microcosms in this study. Compared with the LCS sample, the higher CH4 oxidation activity and toluene-degrading capacity occurred in the WBS sample. The co-existence of toluene in landfill gas would positively or negatively affect CH4 oxidation, mainly depending on the toluene concentrations and exposure time. The nearly complete inhibition of toluene on CH4 oxidation was observed in the WBS sample at the toluene concentration of ?80,000mgm(-3), which was about 10 times higher than that in the LCS sample. The toluene degradation rates in both landfill covers fitted well with the Michaelis-Menten model. These findings showed that WBS was a good alternative landfill cover material to simultaneously mitigate emissions of CH4 and toluene from landfills to the atmosphere. PMID:24801894

Su, Yao; Zhang, Xuan; Wei, Xiao-Meng; Kong, Jiao-Yan; Xia, Fang-Fang; Li, Wei; He, Ruo

2014-06-15

114

Report: landfill alternative daily cover: conserving air space and reducing landfill operating cost.  

PubMed

Title 40, Part 258 of the Code of Federal Regulations, Solid Waste Disposal Facility Criteria, commonly referred to as Subtitle D, became effective on October 9, 1993. It establishes minimum criteria for solid waste disposal facility siting, design, operations, groundwater monitoring and corrective action, and closure and postclosure maintenance, while providing EPA-approved state solid waste regulatory programs flexibility in implementing the criteria. Section 258.21(a) [40 CFR 258.21(a)] requires owners or operators of municipal solid waste landfill (MSWLF) units to cover disposed solid waste with 30cm of earthen material at the end of the operating day, or at more frequent intervals, if necessary, to control disease vectors, fires, odours, blowing litter, and scavenging. This requirement is consistent with already existing solid waste facility regulations in many states. For many MSWLFs, applying daily cover requires the importation of soil which increases landfill operating costs. Daily cover also uses valuable landfill air space, reducing potential operating revenue and the landfill's operating life. 40 CFR 258.21 (b) allows the director of an approved state to approve alternative materials of an alternative thickness if the owner or operator demonstrates that the alternative material and thickness will control disease vectors, fires, odours, blowing litter, and scavenging without presenting a threat to human health and the environment. Many different types of alternative daily cover (ADC) are currently being used, including geosynthetic tarps, foams, garden waste, and auto shredder fluff. These materials use less air space than soil and can reduce operating costs. This paper discusses the variety of ADCs currently being used around the country and their applicability to different climates and operating conditions, highlighting the more unusual types of ADC, the types of demonstrations necessary to obtain approval of ADC, and the impact on landfill air space and operating costs of ADC use. PMID:11525478

Haughey, R D

2001-02-01

115

Field application of nitrogen and phenylacetylene to mitigate greenhouse gas emissions from landfill cover soils: effects on microbial community structure.  

PubMed

Landfills are large sources of CH(4), but a considerable amount of CH(4) can be removed in situ by methanotrophs if their activity can be stimulated through the addition of nitrogen. Nitrogen can, however, lead to increased N(2)O production. To examine the effects of nitrogen and a selective inhibitor on CH(4) oxidation and N(2)O production in situ, 0.5 M of NH(4)Cl and 0.25 M of KNO(3), with and without 0.01% (w/v) phenylacetylene, were applied to test plots at a landfill in Kalamazoo, MI from 2007 November to 2009 July. Nitrogen amendments stimulated N(2)O production but had no effect on CH(4) oxidation. The addition of phenylacetylene stimulated CH(4) oxidation while reducing N(2)O production. Methanotrophs possessing particulate methane monooxygenase and archaeal ammonia-oxidizers (AOAs) were abundant. The addition of nitrogen reduced methanotrophic diversity, particularly for type I methanotrophs. The simultaneous addition of phenylacetylene increased methanotrophic diversity and the presence of type I methanotrophs. Clone libraries of the archaeal amoA gene showed that the addition of nitrogen increased AOAs affiliated with Crenarchaeal group 1.1b, while they decreased with the simultaneous addition of phenylacetylene. These results suggest that the addition of phenylacetylene with nitrogen reduces N(2)O production by selectively inhibiting AOAs and/or type II methanotrophs. PMID:20809077

Im, Jeongdae; Lee, Sung-Woo; Bodrossy, Levente; Barcelona, Michael J; Semrau, Jeremy D

2011-01-01

116

Migration barrier covers for radioactive and mixed waste landfills  

SciTech Connect

Migration barrier cover technology will likely serve as the remediation alternative of choice for most of DOE`s radioactive and mixed waste landfills simply because human and ecological risks can be effectively managed without the use of more expensive alternatives. However, very little testing and evaluation has been done, either before or after installation, to monitor how effective they are in isolating waste or to develop data that can be used to evaluate model predictions of long term performance. Los Alamos National Laboratory has investigated the performance of a variety of landfill capping alternatives since 1981 using large field lysimeters to monitor the fate of precipitation falling on the cap surface. The objective of these studies is to provide the risk manager with a variety of field tested capping designs, of various complexities and costs, so that design alternatives can be matched to the need for hydrologic control at the site. Four different landfill cap designs, representing different complexities and costs, were constructed at Hill Air Force Base (AFB) in October and November, 1989. The designs were constructed in large lysimeters and instrumented to provide estimates of all components of water balance including precipitation, runoff (and soil erosion), infiltration, leachate production, evapotranspiration, and capillary/hydraulic barrier flow. The designs consisted of a typical soil cover to serve as a baseline, a modified EPA RCRA cover, and two versions of a Los Alamos design that contained erosion control measures, an improved vegetation cover to enhance evapotranspiration, and a capillary barrier to divert downward flow of soil water. A comprehensive summary of the Hill AFB demonstration will be available in October 1993, when the project is scheduled to terminate.

Hakonson, T.E.; Manies, K.L.; Warren, R.W.; Bostick, K.V.; Trujillo, G. [Los Alamos National Lab., NM (United States); Kent, J.S. [Air Force Academy, CO (United States). Dept. of Biology; Lane, L.J. [Department of Agriculture, Tucson, AZ (United States)

1993-03-01

117

Migration barrier covers for radioactive and mixed waste landfills  

SciTech Connect

Migration barrier cover technology will likely serve as the remediation alternative of choice for most of DOE's radioactive and mixed waste landfills simply because human and ecological risks can be effectively managed without the use of more expensive alternatives. However, very little testing and evaluation has been done, either before or after installation, to monitor how effective they are in isolating waste or to develop data that can be used to evaluate model predictions of long term performance. Los Alamos National Laboratory has investigated the performance of a variety of landfill capping alternatives since 1981 using large field lysimeters to monitor the fate of precipitation falling on the cap surface. The objective of these studies is to provide the risk manager with a variety of field tested capping designs, of various complexities and costs, so that design alternatives can be matched to the need for hydrologic control at the site. Four different landfill cap designs, representing different complexities and costs, were constructed at Hill Air Force Base (AFB) in October and November, 1989. The designs were constructed in large lysimeters and instrumented to provide estimates of all components of water balance including precipitation, runoff (and soil erosion), infiltration, leachate production, evapotranspiration, and capillary/hydraulic barrier flow. The designs consisted of a typical soil cover to serve as a baseline, a modified EPA RCRA cover, and two versions of a Los Alamos design that contained erosion control measures, an improved vegetation cover to enhance evapotranspiration, and a capillary barrier to divert downward flow of soil water. A comprehensive summary of the Hill AFB demonstration will be available in October 1993, when the project is scheduled to terminate.

Hakonson, T.E.; Manies, K.L.; Warren, R.W.; Bostick, K.V.; Trujillo, G. (Los Alamos National Lab., NM (United States)); Kent, J.S. (Air Force Academy, CO (United States). Dept. of Biology); Lane, L.J. (Department of Agriculture, Tucson, AZ (United States))

1993-01-01

118

METHANE PHYTOREMEDIATION BY VEGETATIVE LANDFILL COVER SYSTEMS  

EPA Science Inventory

Landfill gas, consisting of methane and other gases, is produced from organic compounds degrading in landfills, contributes to global climate change, is toxic to various types of vegetation, and may pose a combustion hazard at higher concentrations. New landfills are required to ...

119

Biotic methane oxidation within an instrumented experimental landfill cover  

Microsoft Academic Search

An experimental landfill cover composed of a mixture of sand and compost was installed at the St-Nicéphore landfill in Québec (Canada). The mixture was evaluated as a potential substrate to promote methane (CH4) oxidation by methanotrophic bacteria. One of the objectives of this field project was to assess the efficiency of the cover in reducing CH4 emissions. For this, both

Louis-B. Jugnia; Alexandre R. Cabral; Charles W. Greer

2008-01-01

120

SETTLEMENT AND COVER SUBSIDENCE OF HAZARDOUS WASTE LANDFILLS  

EPA Science Inventory

Numerical models using equations for linearly elastic deformation were developed to predict the maximum expected amount of settlement and cover subsidence and potential cracking of the cover by differential settlement in uniformly, horizontally layered hazardous waste landfills. ...

121

EVAPOTRANSPIRATION AND CAPILLARY BARRIER FINAL LANDFILL COVERS FACT SHEET  

EPA Science Inventory

The fact sheet provides an overview of two alternative landfill cover designs. It briefly describes advantages and limitations, performance, costs, design and site considerations, and monitoring parameters associated with these cover designs. The document also includes 20 site ...

122

Bio-tarp alternative daily cover prototypes for methane oxidation atop open landfill cells.  

PubMed

Final landfill covers are highly engineered to prevent methane release into the atmosphere. However, methane production begins soon after waste placement and is an unaddressed source of emissions. The methane oxidation capacity of methanotrophs embedded in a "bio-tarp" was investigated as a means to mitigate methane release from open landfill cells. The bio-tarp would also serve as an alternative daily cover during routine landfill operation. Evaluations of nine synthetic geotextiles identified two that would likely be suitable bio-tarp components. Pilot tarp prototypes were tested in continuous flow systems simulating landfill gas conditions. Multilayered bio-tarp prototypes consisting of alternating layers of the two geotextiles were found to remove 16% of the methane flowing through the bio-tarp. The addition of landfill cover soil, compost, or shale amendments to the bio-tarp increased the methane removal up to 32%. With evidence of methane removal in a laboratory bioreactor, prototypes were evaluated at a local landfill using flux chambers installed atop intermediate cover at a landfill. The multilayered bio-tarp and amended bio-tarp configurations were all found to decrease landfill methane flux; however, the performance efficacy of bio-tarps was not significantly different from controls without methanotrophs. Because highly variable methane fluxes at the field site likely confounded the test results, repeat field testing is recommended under more controlled flux conditions. PMID:21354776

Adams, Bryn L; Besnard, Fabien; Bogner, Jean; Hilger, Helene

2011-05-01

123

Alternative Approach for Encouraging Methane Oxidation in Compost Based Landfill Cover Layer with Vegetation  

Microsoft Academic Search

Introduction of compost as landfill cover soil with vegetation practice successfully promoted and maintained methane oxidation efficiency of 80-90% for long-term operation (over 16 months). Compost clearly encouraged for higher methane oxidation according to the beneficial properties of compost, high porosity and water holding capacity. Furthermore, vegetation was also revealed its advantage on sustaining methane oxidation almost throughout soil depth.

Nathiya Tanthachoon; Chart Chiemchaisri; Wilai Chiemchaisri

124

Landfill cover performance monitoring using time domain reflectometry  

SciTech Connect

Time domain reflectometry (TDR) systems were installed to monitor soil moisture in two newly constructed landfill covers at the Idaho National Engineering and Environmental Laboratory. Each TDR system includes four vertical arrays with each array consisting of four TDR probes located at depths of 15, 30, 45, and 60 cm. The deepest probes at 60 cm were installed beneath a compacted soil layer to analyze infiltration through the compacted layer. Based on the TDR data, infiltration through the two covers between March and October, 1997 ranged from less than measurable to 1.5 cm. However, due to a prohibition on penetrating the buried waste and resulting limits on probe placement depths, deeper percolation was not evaluated. Some of the advantages found in the application of TDR for infiltration monitoring at this site are the relative low cost and rugged nature of the equipment. Also, of particular importance, the ability to collect frequent moisture measurements allows the capture and evaluation of soil moisture changes resulting from episodic precipitation events. Disadvantages include the inability to install the probes into the waste, difficulties in interpretation of infiltration during freeze/thaw periods, and some excessive noise in the data.

Neher, E.R.; Cotten, G.B. [Parsons Infrastructure & Technology Group, Inc., Idaho Falls, ID (United States); McElroy, D. [Lockheed-Martin Idaho Technologies Company, Idaho Falls, ID (United States)

1998-03-01

125

Methane oxidation in two Swedish landfill covers measured with carbon-13 to carbon-12 isotope ratios.  

PubMed

The release of methane (CH4) from landfills to the atmosphere and the oxidation of CH4 in the cover soils were quantified with static chambers and a 13C-isotope technique on two landfills in Sweden. One of the landfills had been closed and covered 17 years before this investigation while the other was recently covered. On both landfills, the tops of the landfills were compared with the sloping parts in the summer and winter. Emitted CH4, captured in chambers, was significantly enriched in 13C during summer compared with winter (P < 0.0001), and was enriched relative to anaerobic-zone methane. The difference between emitted and anaerobic zone delta 13C-CH4 was used to estimate soil methane oxidation. In summer, these differences ranged from 9 to 26@1000, and CH4 oxidation was estimated to be between 41 and 50% of the produced CH4 in the new landfill, and between 60 and 94% in the old landfill. In winter, when soil temperature was below 0 degree C, no difference in delta 13C was observed between emitted and anaerobic-zone CH4, suggesting that there was no soil oxidation. The temperature effect shown in this experiment suggests that there may be both seasonal and latitudinal differences in the importance of landfill CH4 oxidation. Finally the isotopic fractionation factor (alpha) varied from 1.023 to 1.038 and was temperature dependent, increasing at colder temperatures. Methanotrophic bacteria appeared to have high growth efficiencies and the majority of the methane consumed in incubations did not result in immediate CO2 production. PMID:11285896

Börjesson, G; Chanton, J; Svensson, B H

2001-01-01

126

75 FR 6597 - Determination to Approve Alternative Final Cover Request for the Lake County, MT Landfill...  

Federal Register 2010, 2011, 2012, 2013

...Alternative Final Cover Request for the Lake County, MT Landfill; Opportunity for...approve an alternative final cover for the Lake County landfill, a municipal solid waste landfill (MSWLF) owned and operated by Lake County, Montana on the Confederated...

2010-02-10

127

Understanding natural and induced gas migration through landfill cover materials: the basis for improved landfill gas recovery  

Microsoft Academic Search

Vertical pressure and concentration gradients in landfill cover materials are being examined at the Mallard North Landfill in Dupage County, IL. The goal of this project is to understand venting of landfill gas and intrusion of atmospheric gases into the landfill in response to changing meteorological conditions (particularly barometric pressure and precipitation) and pumping rates at recovery wells. Nests of

Bogner

1986-01-01

128

Field Performance Of Three Compacted Clay Landfill Covers  

EPA Science Inventory

A study was conducted at sites in subtropical Georgia, seasonal and humid Iowa, and arid southeastern California to evaluate the field hydrology of compacted clay covers for final closure of landfills. Water balance of the covers was monitored with large (10 by 20 m ), instrumen...

129

Observations on the methane oxidation capacity of landfill soils.  

PubMed

The objective of this study was to determine the role of CH(4) loading to a landfill cover in the control of CH(4) oxidation rate (gCH(4)m(-2)d(-1)) and CH(4) oxidation efficiency (% CH(4) oxidation) in a field setting. Specifically, we wanted to assess how much CH(4) a cover soil could handle. To achieve this objective we conducted synoptic measurements of landfill CH(4) emission and CH(4) oxidation in a single season at two Southeastern USA landfills. We hypothesized that percent oxidation would be greatest at sites of low CH(4) emission and would decrease as CH(4) emission rates increased. The trends in the experimental results were then compared to the predictions of two differing numerical models designed to simulate gas transport in landfill covers, one by modeling transport by diffusion only and the second allowing both advection and diffusion. In both field measurements and in modeling, we found that percent oxidation is a decreasing exponential function of the total CH(4) flux rate (CH(4) loading) into the cover. When CH(4) is supplied, a cover's rate of CH(4) uptake (gCH(4)m(-2)d(-2)) is linear to a point, after which the system becomes saturated. Both field data and modeling results indicate that percent oxidation should not be considered as a constant value. Percent oxidation is a changing quantity and is a function of cover type, climatic conditions and CH(4) loading to the bottom of the cover. The data indicate that an effective way to increase the % oxidation of a landfill cover is to limit the amount of CH(4) delivered to it. PMID:20889326

Chanton, Jeffrey; Abichou, Tarek; Langford, Claire; Spokas, Kurt; Hater, Gary; Green, Roger; Goldsmith, Doug; Barlaz, Morton A

2011-05-01

130

Impact of different plants on the gas profile of a landfill cover  

SciTech Connect

Research highlights: > Plants influence gas profile and methane oxidation in landfill covers. > Plants regulate water content and increase the availability of oxygen for methane oxidation. > Plant species with deep roots like alfalfa showed more stimulation of methane oxidation than plants with shallow root systems like grasses. - Abstract: Methane is an important greenhouse gas emitted from landfill sites and old waste dumps. Biological methane oxidation in landfill covers can help to reduce methane emissions. To determine the influence of different plant covers on this oxidation in a compost layer, we conducted a lysimeter study. We compared the effect of four different plant covers (grass, alfalfa + grass, miscanthus and black poplar) and of bare soil on the concentration of methane, carbon dioxide and oxygen in lysimeters filled with compost. Plants were essential for a sustainable reduction in methane concentrations, whereas in bare soil, methane oxidation declined already after 6 weeks. Enhanced microbial activity - expected in lysimeters with plants that were exposed to landfill gas - was supported by the increased temperature of the gas in the substrate and the higher methane oxidation potential. At the end of the first experimental year and from mid-April of the second experimental year, the methane concentration was most strongly reduced in the lysimeters containing alfalfa + grass, followed by poplar, miscanthus and grass. The observed differences probably reflect the different root morphology of the investigated plants, which influences oxygen transport to deeper compost layers and regulates the water content.

Reichenauer, Thomas G., E-mail: thomas.reichenauer@ait.ac.at [Health and Environment Department, Environmental Resources and Technologies, AIT - Austrian Institute of Technology GmbH, 2444 Seibersdorf (Austria); Watzinger, Andrea; Riesing, Johann [Health and Environment Department, Environmental Resources and Technologies, AIT - Austrian Institute of Technology GmbH, 2444 Seibersdorf (Austria); Gerzabek, Martin H. [Institute of Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Applied Life Sciences, Peter Jordan-Strasse 82, 1190 Vienna (Austria)

2011-05-15

131

DESIGN AND CONSTRUCTION OF COVERS FOR SOLID WASTE LANDFILLS  

EPA Science Inventory

The report provides guidelines in selection, design, and construction of cover for management of municipal, industrial, and hazardous solid wastes (with the exception of radioactive waste). Natural soils as cover are the principal subject; however, synthetic membranes, chemicals,...

132

Evaluation of methane oxidation activity in waste biocover soil during landfill stabilization.  

PubMed

Biocover soil has been demonstrated to have high CH(4) oxidation capacity and is considered as a good alternative cover material to mitigate CH(4) emission from landfills, yet the response of CH(4) oxidation activity of biocover soils to the variation of CH(4) loading during landfill stabilization is poorly understood. Compared with a landfill cover soil (LCS) collected from Hangzhou Tianziling landfill cell, the development of CH(4) oxidation activity of waste biocover soil (WBS) was investigated using simulated landfill systems in this study. Although a fluctuation of influent CH(4) flux occurred during landfill stabilization, the WBS covers showed a high CH(4) removal efficiency of 94-96% during the entire experiment. In the LCS covers, the CH(4) removal efficiencies varied with the fluctuation of CH(4) influent flux, even negative ones occurred due to the storage of CH(4) in the soil porosities after the high CH(4) influent flux of ~137 gm(-2) d(-1). The lower concentrations of O(2) and CH(4) as well as the higher concentration of CO(2) were observed in the WBS covers than those in the LCS covers. The highest CH(4) oxidation rates of the two types of soil covers both occurred in the bottom layer (20-30 cm). Compared to the LCS, the WBS showed higher CH(4) oxidation activity and methane monooxygenase activity over the course of the experiment. Overall, this study indicated the WBS worked well for the fluctuation of CH(4) influent flux during landfill stabilization. PMID:22776254

He, Ruo; Wang, Jing; Xia, Fang-Fang; Mao, Li-Juan; Shen, Dong-Sheng

2012-10-01

133

75 FR 50930 - Final Determination To Approve Alternative Final Cover Request for the Lake County, Montana Landfill  

Federal Register 2010, 2011, 2012, 2013

...Alternative Final Cover Request for the Lake County, Montana Landfill AGENCY: Environmental...approve an alternative final cover for the Lake County landfill, a municipal solid waste landfill (MSWLF) owned and operated by Lake County, Montana on the Confederated...

2010-08-18

134

Impact of different plants on the gas profile of a landfill cover.  

PubMed

Methane is an important greenhouse gas emitted from landfill sites and old waste dumps. Biological methane oxidation in landfill covers can help to reduce methane emissions. To determine the influence of different plant covers on this oxidation in a compost layer, we conducted a lysimeter study. We compared the effect of four different plant covers (grass, alfalfa+grass, miscanthus and black poplar) and of bare soil on the concentration of methane, carbon dioxide and oxygen in lysimeters filled with compost. Plants were essential for a sustainable reduction in methane concentrations, whereas in bare soil, methane oxidation declined already after 6 weeks. Enhanced microbial activity - expected in lysimeters with plants that were exposed to landfill gas - was supported by the increased temperature of the gas in the substrate and the higher methane oxidation potential. At the end of the first experimental year and from mid-April of the second experimental year, the methane concentration was most strongly reduced in the lysimeters containing alfalfa+grass, followed by poplar, miscanthus and grass. The observed differences probably reflect the different root morphology of the investigated plants, which influences oxygen transport to deeper compost layers and regulates the water content. PMID:20888746

Reichenauer, Thomas G; Watzinger, Andrea; Riesing, Johann; Gerzabek, Martin H

2011-05-01

135

Methane oxidation in landfill waste biocover soil: kinetics and sensitivity to ambient conditions.  

PubMed

Waste biocover soil was investigated as an alternative in regions with a shortage of landfill cover soil. In the work, effects of the composition, ambient conditions and nitrogen stress on CH(4) oxidation in waste biocover soil were studied. The results showed that the optimal composition of waste biocover soil as a landfill cover material for CH(4) oxidation was original pH value, 45% moisture and a particle size of ? 4mm. CH(4) oxidation rate increased rapidly over a CH(4) concentration range of 0.01-10% (v/v), and kept stable at CH(4) concentrations of 10-30% (v/v). The Michaelis-Menten model showed a good fit for the kinetic of CH(4) oxidation in landfill waste biocover soil with a maximum of 9.03 ?mol/gd.w./h. The average Q(10) was 10.6 in the batch experiments. A level of 5% of oxygen concentration was enough to sustain the activity of methanotrophs community structure in waste biocover soil. Waste biocover soil had low baseline concentrations of NH(4)(+)-N and NO(3)(-)-N. Ammonia volatilization from landfills and nitrification in landfill waste biocover soils might stimulate CH(4) consumption at concentrations below 600 mg/kg. However, the contents of NH(4)(+)-N and NO(3)(-)-N above 1200 mg/kg would inhibit CH(4) oxidation in landfill waste biocover soil. Compared with NO(3)(-)-N, NH(4)(+)-N had a greater stimulating action as nutrient at lower concentrations and inhibitory effect at higher concentrations on CH(4) oxidation in landfill waste biocover soil. PMID:21324662

Wang, Jing; Xia, Fang-Fang; Bai, Yun; Fang, Cheng-Ran; Shen, Dong-Sheng; He, Ruo

2011-05-01

136

LANDFILL LEACHATE CLOGGING OF GEOTEXTILE (AND SOIL) FILTERS  

EPA Science Inventory

The primary leachate collection system of most solid waste landfills contains a filter layer which has historically been a granular soil. ecently, however, various types of geotextile filters have been used to replace the natural soil filters. roject using six different landfill ...

137

Optimization of diagnostic microarray for application in analysing landfill methanotroph communities under different plant covers.  

PubMed

Landfill sites are responsible for 6-12% of global methane emission. Methanotrophs play a very important role in decreasing landfill site methane emissions. We investigated the methane oxidation capacity and methanotroph diversity in lysimeters simulating landfill sites with different plant vegetations. Methane oxidation rates were 35 g methane m-2 day-1 or higher for planted lysimeters and 18 g methane m-2 day-1 or less for bare soil controls. Best methane oxidation, as displayed by gas depth profiles, was found under a vegetation of grass and alfalfa. Methanotroph communities were analysed at high throughput and resolution using a microbial diagnostic microarray targeting the particulate methane monooxygenase (pmoA) gene of methanotrophs and functionally related bacteria. Members of the genera Methylocystis and Methylocaldum were found to be the dominant members in landfill site simulating lysimeters. Soil bacterial communities in biogas free control lysimeters, which were less abundant in methanotrophs, were dominated by Methylocaldum. Type Ia methanotrophs were found only in the top layers of bare soil lysimeters with relatively high oxygen and low methane concentrations. A competetive advantage of type II methanotrophs over type Ia methanotrophs was indicated under all plant covers investigated. Analysis of average and individual results from parallel samples was used to identify general trends and variations in methanotroph community structures in relation to depth, methane supply and plant cover. The applicability of the technology for the detection of environmental perturbations was proven by an erroneous result, where an unexpected community composition detected with the microarray indicated a potential gas leakage in the lysimeter being investigated. PMID:15008813

Stralis-Pavese, Nancy; Sessitsch, Angela; Weilharter, Alexandra; Reichenauer, Thomas; Riesing, Johann; Csontos, József; Murrell, J Colin; Bodrossy, Levente

2004-04-01

138

Impact of different plants on the gas profile of a landfill cover  

Microsoft Academic Search

Methane is an important greenhouse gas emitted from landfill sites and old waste dumps. Biological methane oxidation in landfill covers can help to reduce methane emissions. To determine the influence of different plant covers on this oxidation in a compost layer, we conducted a lysimeter study. We compared the effect of four different plant covers (grass, alfalfa+grass, miscanthus and black

Thomas G. Reichenauer; Andrea Watzinger; Johann Riesing; Martin H. Gerzabek

2011-01-01

139

Mercury Pollution Characteristics in the Soil around Landfill  

Microsoft Academic Search

\\u000a In recent years, landfill and incineration of waste is considered a new mercury pollution, which is paid widespread attention\\u000a by domestic and foreign scientists. This paper studies mercury pollution Characteristics in the soil around Landfill taking\\u000a landfill in Huainan City for an example and using AMA 254 Advanced Mercury Analyzer produced by US LECO Company. The result\\u000a shows that: mercury

JinXiang Yang; MingXu Zhang; XiaoLong Li

140

Desiccation and cracking behavior of three compacted landfill liner soils  

Microsoft Academic Search

Tests were conducted to investigate desiccation cracking of three compacted liner soils obtained from local landfills in southeast Michigan. The soils had low plasticity with varying fines content. Large-scale samples of the soils were subjected to wetting and drying cycles. Surficial dimensions of cracks and suction in the soils were monitored. Surficial dimensions of cracks were quantified using the crack

N Yesiller; C. J Miller; G Inci; K Yaldo

2000-01-01

141

Scaling methane oxidation: from laboratory incubation experiments to landfill cover field conditions.  

PubMed

Evaluating field-scale methane oxidation in landfill cover soils using numerical models is gaining interest in the solid waste industry as research has made it clear that methane oxidation in the field is a complex function of climatic conditions, soil type, cover design, and incoming flux of landfill gas from the waste mass. Numerical models can account for these parameters as they change with time and space under field conditions. In this study, we developed temperature, and water content correction factors for methane oxidation parameters. We also introduced a possible correction to account for the different soil structure under field conditions. These parameters were defined in laboratory incubation experiments performed on homogenized soil specimens and were used to predict the actual methane oxidation rates to be expected under field conditions. Water content and temperature corrections factors were obtained for the methane oxidation rate parameter to be used when modeling methane oxidation in the field. To predict in situ measured rates of methane with the model it was necessary to set the half saturation constant of methane and oxygen, K(m), to 5%, approximately five times larger than laboratory measured values. We hypothesize that this discrepancy reflects differences in soil structure between homogenized soil conditions in the lab and actual aggregated soil structure in the field. When all of these correction factors were re-introduced into the oxidation module of our model, it was able to reproduce surface emissions (as measured by static flux chambers) and percent oxidation (as measured by stable isotope techniques) within the range measured in the field. PMID:21196106

Abichou, Tarek; Mahieu, Koenraad; Chanton, Jeff; Romdhane, Mehrez; Mansouri, Imane

2011-05-01

142

Field Performance of Three Compacted Clay Landfill Covers  

SciTech Connect

A study was conducted at sites in subtropical Georgia, seasonal and humid Iowa, and arid southeastern California to evaluate the field hydrology of compacted clay covers for final closure of landfills.Water balance of the covers was monitored with large (10 by 20 m), instrumented drainage lysimeters for 2 to 4 yr. Initial drainage at the Iowa and California sites was ,32 mm yr21 (i.e., unit gradient flow for a hydraulic conductivity of 1027 cm s21, the regulatory standard for the clay barriers in this study); initial drainage rate at the Georgia site was about 80 mm yr21. The drainage rate at all sites increased by factors ranging from 100 to 750 during the monitoring periods and in each case the drainage rate exceeded 32 mm yr21 by the end of the monitoring period. The drainage rates developed a rapid response to precipitation events, suggesting that increases in drainage rate were the result of preferential flow. Although no direct observations of preferential flow paths were made, field measurements of water content and temperature at all three sites suggested that desiccation or freeze–thaw cycling probably resulted in formation of preferential flow paths through the barrier layers. Data from all three sites showed the effectiveness of all three covers as hydraulic barriers diminished during the 2 to 4 yr monitoring period, which was short compared with the required design life (often 30 yr) of most waste containment facilities.

Albright, William H.; Benson, Craig H.; Gee, Glendon W.; Abichou, Tarek; Tyler, Scott W.; Rock, Steven

2006-11-01

143

Successive development of soil ecosystems at abandoned coal-ash landfills.  

PubMed

The main goal of the present study was to determine the effect of the native vegetation on the successive development of the soil ecosystem at abandoned coal-ash landfills of the Angren coal-fired power plant in Uzbekistan. Two different landfills (one not in use for 3 years, termed newer, and the other not in use for 10 years, termed older) with different degrees of vegetation cover were chosen to assess the time and vegetation effects on soil biota and habitat development. The soil biotic structure, including soil microorganisms and soil free-living nematode communities, was investigated both at open plots and under different native plants at the coal-ash landfill area. The observed soil microorganisms were found to be the most important component of the observed ecosystems. Total abundance, biomass, species, trophic and sexual diversity of soil free-living nematodes, along with fungi and organic-matter content, were found to be correlated with trace metals. The nematode trophic and species abundance and diversity increased from the newer toward the older coal-ash landfills. The sex ratio of the nematode communities was found to be dependent on the environmental conditions of the study area, with the males being the most sensitive nematode group. All applied ecological indices confirmed that open landfill plots distant from plants are the most unfavorable areas for soil biota. In that respect, the native plants Alhagi maurorum Desv. and Tamarix sp. were found to be important environmental components for the natural remediation of a soil ecosystem in the coal-ash landfill area. PMID:24676936

Pen-Mouratov, Stanislav; Shukurov, Nosir; Yu, Jun; Rakhmonkulova, Shakhnoza; Kodirov, Obidjon; Barness, Gineta; Kersten, Michael; Steinberger, Yosef

2014-07-01

144

Characterization of methane, benzene and toluene-oxidizing consortia enriched from landfill and riparian wetland soils.  

PubMed

The microbial oxidations of methane (M) and volatile organic compounds (VOCs) were compared with those of M and VOCs alone after enriching soil samples with M and/or VOCs. Landfill cover and riparian wetland soils from which M and VOCs were simultaneously emitted were selected as representative samples. Benzene (B) and toluene (T) were employed as the model VOCs. With the landfill soil consortia, the rate of M oxidation decreased from 4.15-5.56 to 2.26-3.42 ?mol g-dry soil(-1)h(-1) in the presence of both B and T, but with the wetland soil consortia the rate of M oxidation (3.09 ?mol g-dry soil(-1)h(-1)) in the mixture of M as well as both B and T was similar to that of M alone (3.04 ?mol g-dry soil(-1)h(-1)). Compared with the methanotrophic community with M alone, the portion of type II methanotrophs was greater in the landfill consortia; whereas, the proportion in wetland consortia was less in the presence of both B and T. The oxidations of B and T were stimulated by the presence of M with both the landfill and wetland consortia. There were no correlations between the oxidation rate of M and those of B and T with the gene copy numbers of pmoA and tmoA responsible for the oxidations. PMID:20832163

Lee, Eun-Hee; Park, Hyunjung; Cho, Kyung-Suk

2010-12-15

145

Improving the aeration of critical fine-grained landfill top cover material by vegetation to increase the microbial methane oxidation efficiency  

Microsoft Academic Search

The natural methane oxidation potential of methanotrophic bacteria in landfill top covers is a sustainable and inexpensive method to reduce methane emissions to the atmosphere. Basically, the activity of methanotrophic bacteria is limited by the availability of oxygen in the soil. A column study was carried out to determine whether and to what extent vegetation can improve soil aeration and

Sonja Bohn; Paul Brunke; Julia Gebert; Johannes Jager

2011-01-01

146

Design of top covers supporting aerobic in situ stabilization of old landfills--an experimental simulation in lysimeters.  

PubMed

Landfill aeration by means of low pressure air injection is a promising tool to reduce long term emissions from organic waste fractions through accelerated biological stabilization. Top covers that enhance methane oxidation could provide a simple and economic way to mitigate residual greenhouse gas emissions from in situ aerated landfills, and may replace off-gas extraction and treatment, particularly at smaller and older sites. In this respect the installation of a landfill cover system adjusted to the forced-aerated landfill body is of great significance. Investigations into large scale lysimeters (2 × 2 × 3m) under field conditions have been carried out using different top covers including compost materials and natural soils as a surrogate to gas extraction during active low pressure aeration. In the present study, the emission behaviour as well as the water balance performance of the lysimeters has been investigated, both prior to and during the first months of in situ aeration. Results reveal that mature sewage sludge compost (SSC) placed in one lysimeter exhibits in principle optimal ambient conditions for methanotrophic bacteria to enhance methane oxidation. Under laboratory conditions the mature compost mitigated CH(4) loadings up to 300 lCH(4)/m(2)d. In addition, the compost material provided high air permeability even at 100% water holding capacity (WHC). In contrast, the more cohesive, mineral soil cover was expected to cause a notably uniform distribution of the injected air within the waste layer. Laboratory results also revealed sufficient air permeability of the soil materials (TS-F and SS-Z) placed in lysimeter C. However, at higher compaction density SS-Z became impermeable at 100% WHC. Methane emissions from the reference lysimeter with the smaller substrate cover (12-52 g CH(4)/m(2)d) were significantly higher than fluxes from the other lysimeters (0-19 g CH(4)/m(2)d) during in situ aeration. Regarding water balance, lysimeters covered with compost and compost-sand mixture, showed the lowest leachate rate (18-26% of the precipitation) due to the high water holding capacity and more favourable plant growth conditions compared to the lysimeters with mineral, more cohesive, soil covers (27-45% of the precipitation). On the basis of these results, the authors suggest a layered top cover system using both compost material as well as mineral soil in order to support active low-pressure aeration. Conventional soil materials with lower permeability may be used on top of the landfill body for a more uniform aeration of the waste due to an increased resistance to vertical gas flow. A compost cover may be built on top of the soil cover underlain by a gas distribution layer to improve methane oxidation rates and minimise water infiltration. By planting vegetation with a high transpiration rate, the leachate amount emanating from the landfill could be further minimised. The suggested design may be particularly suitable in combination with intermittent in situ aeration, in the later stage of an aeration measure, or at very small sites and shallow deposits. The top cover system could further regulate water infiltration into the landfill and mitigate residual CH(4) emissions, even beyond the time of active aeration. PMID:22749719

Hrad, Marlies; Huber-Humer, Marion; Wimmer, Bernhard; Reichenauer, Thomas G

2012-12-01

147

Bio-tarp alternative daily cover prototypes for methane oxidation atop open landfill cells  

Microsoft Academic Search

Final landfill covers are highly engineered to prevent methane release into the atmosphere. However, methane production begins soon after waste placement and is an unaddressed source of emissions. The methane oxidation capacity of methanotrophs embedded in a “bio-tarp” was investigated as a means to mitigate methane release from open landfill cells. The bio-tarp would also serve as an alternative daily

Bryn L. Adams; Fabien Besnard; Jean Bogner; Helene Hilger

2011-01-01

148

Boron in irrigation water and its interactions with soil and plants: an example of municpal landfill leachate reuse  

Microsoft Academic Search

In several countries, leachate is successfully treated by recirculation to the vegetated landfill cover, as it contains several micro and macronutrients for plant growth. However, the proportion and concentration of some parameters can negatively affect the plant growth and soil quality in the case of high leachate input. The presented research discusses B in leachate and its interactions with soil

Maja ZUPAN?I? JUSTIN

149

Deployment of an alternative cover and final closure of the Mixed Waste Landfill, Sandia National Laboratories, Albuquerque, New Mexico.  

SciTech Connect

An alternative cover design consisting of a monolithic layer of native soil is proposed as the closure path for the Mixed Waste Landfill at Sandia National Laboratories, New Mexico. The proposed design would rely upon soil thickness and evapotranspiration to provide long-term performance and stability, and would be inexpensive to build and maintain. The proposed design is a 3-ft-thick, vegetated soil cover. The alternative cover meets the intent of RCRA Subtitle C regulations in that: (a) water migration through the cover is minimized; (b) maintenance is minimized by using a monolithic soil layer; (c) cover erosion is minimized by using erosion control measures; (d) subsidence is accommodated by using a ''soft'' design; and (e) the permeability of the cover is less than or equal to that of natural subsurface soil present. Performance of the proposed cover is integrated with natural site conditions, producing a ''system performance'' that will ensure that the cover is protective of human health and the environment. Natural site conditions that will produce a system performance include: (a) extremely low precipitation and high potential evapotranspiration; (b) negligible recharge to groundwater; (c) an extensive vadose zone; (d) groundwater approximately 500 ft below the surface; and (e) a versatile, native flora that will persist indefinitely as a climax ecological community with little or no maintenance.

Peace, Gerald (Jerry) L.; Goering, Timothy James (GRAM, Inc., Albuquerque, NM); McVey, Michael David (GRAM, Inc., Albuquerque, NM); Borns, David James

2003-06-01

150

Suitability of Hydrologic Evaluation of Landfill Performance (HELP) model of the US Environmental Protection Agency for the simulation of the water balance of landfill cover systems  

Microsoft Academic Search

Cover systems are widely used to safeguard landfills and contaminated sites. The evaluation of the water balance is crucial\\u000a for the design of landfill covers. The Hydrologic Evaluation of Landfill Performance (HELP) model of the US Environmental\\u000a Protection Agency was developed for this purpose. This paper discusses some limitations of version 2 of this model and some\\u000a operational difficulties for

K. Berger; S. Melchior; G. Miehlich

1996-01-01

151

Measurement of microbial biomass and activity in landfill soils  

Microsoft Academic Search

Two complementary techniques, which have been widely used to provide a general measure of microbial biomass or microbial activity in natural soils, were evaluated for their applicability to soils from the Mallard North and Mallard Lake Landfills, DuPage County, Illinois, U.S.A. Included were: (1) a potassium sulphate extraction technique with quantification of organic carbon for measurement of microbial biomass; and

J. E. Bogner; R. M. Miller; K. Spokas

1995-01-01

152

Landfill cover revegetation using organic amendments and cobble mulch in the arid southwest  

SciTech Connect

Cobble mulch and composted biosolids, greenwaste, and dairy manure were added to arid soil in an attempt to improve plant establishment and production, minimize erosion, increase evapotranspiration, and reduce leaching. Twenty-four plots (10 x 10 m) were established in a completely randomized block design (8 treatments, 3 plots per treatment). Treatments included (1) non-irrigated control, (2) irrigated control, (3) non-irrigated greenwaste compost (2.5 yd{sup 3} per plot), (4) irrigated greenwaste compost (5 yd{sup 3} per plot), (5) non-irrigated biosolids compost (2.5 yd{sup 3} per plot), (6) irrigated biosolids compost (5 yd{sup 3} per plot), (7) cobble-mulch, and (8) non-irrigated dairy manure compost (2.5 yd{sup 3} per plot). Soil samples were collected from each plot for laboratory analyses to assess organic matter contents, macro-nutrient levels and trace metal contents, and nitrogen mineralization potential. All plots were seeded similarly with approximately equal portions of cool and warm season native grasses. The organic composts (greenwaste, biosolids, dairy manure) added to the soils substantially increased soil organic matter and plant nutrients including total nitrogen and phosphorus. However, the results of a laboratory study of the soils' nitrogen mineralization potential after the application of the various composts showed that the soil nitrogen-supplying capability decreased to non-amended soil levels by the start of the second growing season. Thus, from the standpoint of nitrogen fertilizer value, the benefits of the organic compost amendments appear to have been relatively short-lived. The addition of biosolids compost, however, did not produce significant changes in the soils' copper, cadmium, lead, and zinc concentrations and thus did not induce adverse environmental conditions due to excessive heavy metal concentrations. Supplemental irrigation water during the first and second growing seasons did not appear to increase plant biomass production in the irrigated control plots over that produced in the non-irrigated control plots. This surprising result was probably due to the cumulative effects of other factors that influenced the initial establishment and production of plants in the plots (e.g., plant species competition, seed germination delay times, differences in nutrient release and availability). Variation within individual plots, and among the three replicate plots associated with each treatment, rendered many of the recorded differences in vegetation establishment and production statistically insignificant. However, after two complete growing seasons the highest total plant foliar cover and the greatest biomass production and plant species diversity occurred in the cobble-mulched plots. These results suggest that cobble-mulch may be the desired amendment in re-vegetated arid landfill covers if the principal objectives are to quickly establish vegetation cover, stabilize the site from erosion, and increase water usage by plants, thereby reducing the potential for leaching and contaminant movement from the landfill's waste-bearing zone.

AGUILAR,RICHARD; DWYER,STEPHEN F.; REAVIS,BRUCE A.; NEWMAN,GRETCHEN CARR; LOFTIN,SAMUEL R.

2000-02-01

153

A RULE-BASED SYSTEM FOR EVALUATING FINAL COVERS FOR HAZARDOUS WASTE LANDFILLS  

EPA Science Inventory

This chapter examines how rules are used as a knowledge representation formalism in the domain of hazardous waste management. A specific example from this domain involves performance evaluation of final covers used to close hazardous waste landfills. Final cover design and associ...

154

Field Performance Of A Compacted Clay Landfill Final Cover At A Humid Site  

EPA Science Inventory

A study was conducted in southern Georgia, USA, to evalaute how the hydraulic properties of the compacted clay barrier layer in a final landfill cover changed over a 4-year service life. The cover was part of a test section constructed in a large drainage lysimeter that allowed ...

155

A mechanical approach for fibre-reinforced clay in landfill caps cover application  

Microsoft Academic Search

Solid waste landfills come with a cover barrier which includes a compacted clay liner essential to safety on site. However this barrier encounters numerous problems, in particular those related to in situ implementation and to mechanical loading which may cause stress in the clay layer leading to the development of cracks. Tensile stress damage is replaced by shearing when the

Olivier Plé; Hà Lê; Philippe Gotteland

2009-01-01

156

Flux estimates from soil methanogenesis and methanotrophy: Landfills, rice paddies, natural wetlands and aerobic soils  

Microsoft Academic Search

Present and future annual methane flux estimates out of landfills, rice paddies and natural wetlands, as well as the sorption capacity of aerobic soils for atmospheric methane, are assessed. The controlling factors and uncertainties with regard to soil methanogenesis and methanotrophy are also briefly discussed.

Pascal Boeckx; OSWALD VAN CLEEMPUT

1996-01-01

157

A Comprehensive Numerical Model Simulating Gas, Heat, and Moisture Transport in Sanitary Landfills and Methane Oxidation in Final Covers  

Microsoft Academic Search

A model to simulate gas, heat, and moisture transport through a sanitary landfill has been developed. The model not only considers\\u000a the different processes that go on in a landfill but also the oxidation of methane in the final cover. The model was calibrated\\u000a using published results and field data from a pilot scale landfill in Calgary. The model captures

Anurag Garg; Gopal Achari

2010-01-01

158

Assessment of an active dry barrier for a landfill cover system  

SciTech Connect

A dry barrier is a layer of geologic material that is dried by air flow. An active dry barrier system can be designed, installed, and operated as part of a landfill cover system. An active system uses blowers and fans to move air through a high-permeability layer within the cover system. Depending principally on the air-flow rate, it is possible for a dry barrier to remove enough water to substantially reduce the likelihood of water percolating through the cover system. If a material with a relatively great storage capacity, such as processed tuff, is used as the coarse layer, then the efficiency of the dry barrier will be increased.

Stormont, J.C. [Sandia National Labs., Albuquerque, NM (United States); Ankeny, M.D.; Burkhard, M.E.; Tansey, M.K.; Kelsey, J.A. [Stephens (Daniel B.) and Associates, Inc., Albuquerque, NM (United States)

1994-03-01

159

Global climate changes and the soil cover  

NASA Astrophysics Data System (ADS)

The relationships between climate changes and the soil cover are analyzed. The greenhouse effect induced by the rising concentrations of CO2, CH4, N2O, and many other trace gases in the air has been one of the main factors of the global climate warming in the past 30-40 years. The response of soils to climate changes is considered by the example of factual data on soil evolution in the dry steppe zone of Russia. Probable changes in the carbon cycle under the impact of rising CO2 concentrations are discussed. It is argued that this rise may have an effect of an atmospheric fertilizer and lead to a higher productivity of vegetation, additional input of organic residues into the soils, and activation of soil microflora. Soil temperature and water regimes, composition of soil gases, soil biotic parameters, and other dynamic soil characteristics are most sensitive to climate changes. For the territory of Russia, in which permafrost occupies more than 50% of the territory, the response of this highly sensitive natural phenomenon to climate changes is particularly important. Long-term data on soil temperatures at a depth of 40 cm are analyzed for four large regions of Russia. In all of them, except for the eastern sector of Russian Arctic, a stable trend toward the rise in the mean annual soil temperature. In the eastern sector (the Verkhoyansk weather station), the soil temperature remains stable.

Kudeyarov, V. N.; Demkin, V. A.; Gilichinskii, D. A.; Goryachkin, S. V.; Rozhkov, V. A.

2009-09-01

160

Feasibility Study, Primary Designs and Development of Alternative Evapotranspiration Covers for Landfills and Waste Dump Sites in Tropical Locations  

Microsoft Academic Search

People generate a large and ever-increasing volume of waste, which originates in rural and urban areas, industrial operations and other activities. In spite of waste recycling, which is the solution to the huge amount of solid waste, a large part of it is deposited into landfills, dumps, etc.Landfills are, at present, the most widely used waste disposal facilities. Final cover

Francisco Jose Escobar

2010-01-01

161

Methane flux and oxidation at two types of intermediate landfill covers  

SciTech Connect

Methane emissions were measured on two areas at a Florida (USA) landfill using the static chamber technique. Because existing literature contains few measurements of methane emissions and oxidation in intermediate cover areas, this study focused on field measurement of emissions at 15-cm-thick non-vegetated intermediate cover overlying 1-year-old waste and a 45-cm-thick vegetated intermediate cover overlying 7-year-old waste. The 45 cm thick cover can also simulate non-engineered covers associated with older closed landfills. Oxidation of the emitted methane was evaluated using stable isotope techniques. The arithmetic means of the measured fluxes were 54 and 22 g CH{sub 4} m{sup -2} d{sup -1} from the thin cover and the thick cover, respectively. The peak flux was 596 g m{sup -2} d{sup -1} for the thin cover and 330 g m{sup -2} d{sup -1} for the thick cover. The mean percent oxidation was significantly greater (25%) at the thick cover relative to the thin cover (14%). This difference only partly accounted for the difference in emissions from the two sites. Inverse distance weighing was used to describe the spatial variation of flux emissions from each cover type. The geospatial mean flux was 21.6 g m{sup -2} d{sup -1} for the thick intermediate cover and 50.0 g m{sup -2} d{sup -1} for the thin intermediate cover. High emission zones in the thick cover were fewer and more isolated, while high emission zones in the thin cover were continuous and covered a larger area. These differences in the emission patterns suggest that different CH{sub 4} mitigation techniques should be applied to the two areas. For the thick intermediate cover, we suggest that effective mitigation of methane emissions could be achieved by placement of individualized compost cells over high emission zones. Emissions from the thin intermediate cover, on the other hand, can be mitigated by placing a compost layer over the entire area.

Abichou, Tarek [Department of Civil and Environmental Engineering, Florida A and M University, Florida State University, College of Engineering, Tallahassee, FL 32310 (United States)]. E-mail: abichou@eng.fsu.edu; Chanton, Jeffery [Department of Oceanography, Florida State University, Tallahassee, FL 32306 (United States); Powelson, David [Department of Oceanography, Florida State University, Tallahassee, FL 32306 (United States); Fleiger, Jill [Department of Oceanography, Florida State University, Tallahassee, FL 32306 (United States); Escoriaza, Sharon [Department of Civil and Environmental Engineering, Florida A and M University, Florida State University, College of Engineering, Tallahassee, FL 32310 (United States); Lei, Yuan [Department of Civil and Environmental Engineering, Florida A and M University, Florida State University, College of Engineering, Tallahassee, FL 32310 (United States); Stern, Jennifer [Department of Geology, Florida State University, Tallahassee, FL 32306 (United States)

2006-07-01

162

PHYTOEXTRACTION OF AS AND FE USING HIBISCUS CANNABINUS L. FROM SOIL POLLUTED WITH LANDFILL LEACHATE  

Microsoft Academic Search

Terrestrial plants as potential phytoremediators for remediation of surface soil contaminated with toxic metals have gained attention in clean-up technologies. The potential of kenaf (Hibiscus cannabinus L.) to offer a cost-effective mechanism to remediate Fe and As from landfill leachate-contaminated soil was investigated. Pot experiment employing soil polluted with treatments of Jeram landfill leachate was conducted for 120 days. Plants

M. Meera; P. Agamuthu

2012-01-01

163

Phytoextraction of As and Fe using Hibiscus cannabinus L. from Soil Polluted with Landfill Leachate  

Microsoft Academic Search

Terrestrial plants as potential phytoremediators for remediation of surface soil contaminated with toxic metals have gained attention in clean-up technologies. The potential of kenaf (Hibiscus cannabinus L.) to offer a cost-effective mechanism to remediate Fe and As from landfill leachate-contaminated soil was investigated. Pot experiment employing soil polluted with treatments of Jeram landfill leachate was conducted for 120 days. Plants

Meera Munusamy; Agamuthu Pariathamby

2011-01-01

164

Geological and geotechnical characteristics of Metro Manila volcanic soils and their suitability for landfill soil liner  

NASA Astrophysics Data System (ADS)

Due to the Philippines's island-arc setting, andesitic tuff and volcanic ash constitute two-thirds of the country's agricultural land. In situ weathering of these volcanic sediments produces volcanic soils. Metro Manila volcanic soils were studied to determine their suitability for landfill soil liner. The soils were analyzed using XRD and XRF, and were tested for geotechnical properties. The results show the presence of the smectite group, a swelling variety of clay. The smectite-type clays are weathering products of volcanic glasses which are dominant components of the parental rocks. The high amounts of Al2O3 indicate an Al-rich type of soil. The clay species is either di- or tri-octahedral type, which points to montmorillonite as the main clay species. Swelling clay lowers the permeability of soils and reduces the infiltration and lateral movement of leachates in the ground. Also, geotechnical tests revealed moderate to high plasticity indices and low hydraulic conductivity values. The study shows that the physicochemical characteristics of volcanic soils meet the criteria for a soil liner for future sanitary landfill projects as mandated by RA 9003, a recently ratified solid waste management act of the Philippines. Being widespread, volcanic soils can be viewed as an important resource of the country.

Mendoza, Edna Patricia; Catane, Sandra; Pascua, Chelo; Zarco, Mark Albert

2010-05-01

165

Use of a biologically active cover to enhance landfill methane oxidation  

NASA Astrophysics Data System (ADS)

The emplacement of a biocover composed of a glass dispersion layer and a compost layer at the Tallahassee MSW Landfill significantly reduced methane emissions (by a factor of 10) and doubled the oxidation of methane compared to a non-treated control area of the landfill. The biocover became more effective than the control in oxidizing methane three months after its initial emplacement. Percent oxidation of methane was calculated using the carbon isotopic composition and concentration of methane emitted at the surface of the landfill. Over the one-year period of study, the difference in methane emission rate and methane oxidation percentage in the control and the biocover were statistically significant (p < 0.001). Following the initial three-month curing period, the mean oxidation for the biocover was 38%, and the mean oxidation for the control was 19%. Following the three month curing period 29 negative fluxes and 27 zero fluxes were observed in the biocover, while only 6 negative fluxes and 22 zero fluxes were onserved in the control area. Negative fluxes indicate uptake of atmospheric methane. If these zero and negative fluxes are assumed to represent 100% oxidation then the mean percent oxidation for the biocover and control areas increase to 56% and 39% respectively. Individual flux chambers showed a negative correlation between soil moisture and oxidation and a positive correlation between soil temperature and oxidation. Neither flux nor oxidation exhibited a distinct seasonality, perhaps due to relatively warm temperatures throughout the year or the effects of soil moisture buffering the effects of temperature.

Stern, J. C.; Chanton, J.; Abichou, T.; Powelson, D.; Yuan, L.; Bogner, J.

2005-12-01

166

PREDICTION/MITIGATION OF SUBSIDENCE DAMAGE TO HAZARDOUS WASTE LANDFILL COVERS  

EPA Science Inventory

Characteristics of Resource Conservation and Recovery Act hazardous waste landfills and of landfilled hazardous wastes have been described to permit development of models and other analytical techniques for predicting, reducing, and preventing landfill settlement and related cove...

167

Influence of xenobiotic contaminants on landfill soil microbial activity and diversity  

Microsoft Academic Search

Landfills are often the final recipient of a range of environmentally important contaminants such as hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). In this study the influence of these contaminants on microbial activity and diversity was assessed in a municipal solid waste (MSW) landfill placed in Torrejón de Ardoz (Madrid, Spain).Soil samples were collected from four selected areas

M. I. Pérez-Leblic; A. Turmero; M. Hernández; A. J. Hernández; J. Pastor; A. S. Ball; J. Rodríguez; M. E. Arias

2010-01-01

168

CHEMICAL AND PHYSICAL EFFECTS OF MUNICIPAL LANDFILLS ON UNDERLYING SOILS AND GROUNDWATER  

EPA Science Inventory

Three municipal landfill sites in the eastern and central United States were studied to determine the effects of the disposal facilities on surrounding soils and groundwater. Borings were made up the groundwater gradient, down the groundwater gradient and through the landfill. So...

169

Successive development of soil ecosystems at abandoned coal-ash landfills  

Microsoft Academic Search

The main goal of the present study was to determine the effect of the native vegetation on the successive development of the soil ecosystem at abandoned coal-ash landfills of the Angren coal-fired power plant in Uzbekistan. Two different landfills (one not in use for 3 years, termed newer, and the other not in use for 10 years, termed older) with

Stanislav Pen-Mouratov

2014-01-01

170

A Water Balance Study of Four Landfill Cover Designs at Material Disposal Area B in Los Alamos, New Mexico  

SciTech Connect

The goal of disposing of low-level radioactive and hazardous waste in shallow landfills is to reduce risk to human health and the environment by isolating contaminants until they no longer pose an unacceptable hazard. In order to achieve this, the Department of Energy Environmental Restoration Program is comparing the performance of several different surface covers at Material Disposal Area (MDA) B in Los Alamos. Two conventional landfill were compared with an improved cover designed to minimize plant and animal intrusion and to minimize water infiltration into the underlying wastes. The conventional covers varied in depth and both conventional and improved designs had different combinations of vegetation (grass verses shrub) and gravel mulch (no mulch verses mulch). These treatments were applied to each of 12 plots and water balance parameters were measured from March1987 through June 1995. Adding a gravel mulch significantly influenced the plant covered field plots receiving no gravel mulch averaged 21.2% shrub cover, while plots with gravel had a 20% larger percent cover of shrubs. However, the influence of gravel mulch on the grass cover was even larger than the influence on shrub cover, average grass cover on the plots with no gravel was 16.3%, compared with a 42% increase in grass cover due to gravel mulch. These cover relationships are important to reduce runoff on the landfill cover, as shown by a regression model that predicts that as ground cover is increased from 30 to 90%,annual runoff is reduced from 8.8 to 0.98 cm-a nine-fold increase. We also found that decreasing the slope of the landfill cover from 6 to 2% reduced runoff from the landfill cover by 2.7-fold. To minimize the risk of hazardous waste from landfills to humans, runoff and seepage need to be minimized and evapotranspiration maximized on the landfill cover. This has to be accomplished for dry and wet years at MDA B. Seepage consisted of 1.9% and 6.2% of the precipitation in the average and once in ten year events, respectively, whereas corresponding values for runoff were 13% and 16%; these changes were accompanied by corresponding decreases in evapotranspiration, which accounted for 86% and only 78% of the precipitation occurring on the average and once in ten year even~ respectively.

David D. Breshears; Fairley J. Barnes; John W. Nyhan; Johnny A. Salazar

1998-09-01

171

Evaluation of Groundwater and Soil Pollution in a Landfill Area Using Electrical Resistivity Imaging Survey  

Microsoft Academic Search

Landfills are sources of groundwater and soil pollution due to the production of leachate and its migration through refuse.\\u000a This study was conducted in order to determine the extent of groundwater and soil pollution within and around the landfill\\u000a of Seri Petaling located in the State of Selangor, Malaysia. The condition of nearby surface water was also determined. An\\u000a electrical

ABDELATIF MUKHTAR AHMED; WAN NORAZMIN SULAIMAN

2001-01-01

172

Steel slags in a landfill top cover--experiences from a full-scale experiment.  

PubMed

A full scale field study has been carried out in order to test and evaluate the use of slags from high-alloy steel production as the construction materials for a final cover of an old municipal landfill. Five test areas were built using different slag mixtures within the barrier layer (liner). The cover consisted of a foundation layer, a liner with a thickness of 0.7 m, a drainage layer of 0.3 m, a protection layer of 1.5 m and a vegetation layer of 0.25 m. The infiltration varied depending on the cover design used, mainly the liner recipe but also over time and was related to seasons and precipitation intensity. The test areas with liners composed of 50% electric arc furnace (EAF) slag and 50% cementitious ladle slag (LS) on a weight basis and with a proper consistence of the protection layer were found to meet the Swedish infiltration criteria of ?50 l (m(2)a)(-1) for final covers for landfills for non-hazardous waste: the cumulative infiltration rates to date were 44, 19 and 0.4 l (m(2)a)(-1) for A1, A4 and A5, respectively. Compared to the precipitation, the portion of leachate was always lower after the summer despite high precipitation from June to August. The main reason for this is evapotranspiration but also the fact that the time delay in the leachate formation following a precipitation event has a stronger effect during the shorter summer sampling periods than the long winter periods. Conventional techniques and equipment can be used but close cooperation between all involved partners is crucial in order to achieve the required performance of the cover. This includes planning, method and equipment testing and quality assurance. PMID:24393476

Andreas, L; Diener, S; Lagerkvist, A

2014-03-01

173

Site Specific Landfill CH4 Emissions: Shortcomings of National GHG Inventory Guidelines and a New Process-Based Approach Linked to Climate and Soil Microclimate  

NASA Astrophysics Data System (ADS)

Current (2006) IPCC national GHG inventory guidelines for landfill CH4, which estimate CH4 generation from the mass of waste in place, have high uncertainties, cannot be reliably related to measured emissions at specific sites, and lack comprehensive field validation. Moreover, measured landfill CH4 emissions vary over a wide range from >1000 g/m2/d down to negative values (uptake of atmospheric CH4). Literature over the last decade has emphasized that the major factors controlling emissions in these highly managed soil systems are gaseous transport rates as affected by the thickness and physical properties of cover soils, methanotrophic CH4 oxidation in cover materials as a function of seasonal soil microclimate. and the presence or absence of engineered gas extraction. Thus we developed and field validated a new site specific annual inventory model that incorporates specific soil profile properties and soil microclimate modeling coupled to 0.5° scale global climatic models. Based on 1D diffusion, CALMIM (California Landfill Methane Inventory Model) is a freely available JAVA tool which models a typical annual cycle for CH4 emissions from site specific daily, intermediate, and final landfill cover designs. This new approach, which is compliant with IPCC Tier III criteria, was originally field validated at two California sites (Monterey County; Los Angeles County), with limited field validation at three additional California sites. In addition to regional defaults for inventory purposes, CALMIM permits user selectable parameters and boundary conditions for more rigorous site specific applications where detailed CH4 emissions, meteorological, and soil microclimate data exist. We report here on improvements and expanded international field validation for CALMIM 5.2 in collaboration with research groups in the U.S., Europe, Africa, Asia, and Australia.odeled and measured annual cycle of landfill CH4 emissions for Austrian site. Cover consists of 50 cm sand & gravel overlain by 110 cm loam & sandy loam. No gas recovery. Site 100% vegetated.

Bogner, J. E.; Spokas, K.; Corcoran, M.

2012-12-01

174

Improving the aeration of critical fine-grained landfill top cover material by vegetation to increase the microbial methane oxidation efficiency.  

PubMed

The natural methane oxidation potential of methanotrophic bacteria in landfill top covers is a sustainable and inexpensive method to reduce methane emissions to the atmosphere. Basically, the activity of methanotrophic bacteria is limited by the availability of oxygen in the soil. A column study was carried out to determine whether and to what extent vegetation can improve soil aeration and maintain the methane oxidation process. Tested soils were clayey silt and mature compost. The first soil is critical in light of surface crusting due to vertical erosion of an integral part of fine-grained material, blocking pores required for the gas exchange. The second soil, mature compost, is known for its good methane oxidation characteristics, due to high air-filled porosity, favorable water retention capacity and high nutrient supply. The assortment of plants consisted of a grass mixture, Canadian goldenrod and a mixture of leguminous plants. The compost offered an excellent methane oxidation potential of 100% up to a CH(4)-input of 5.6l CH(4)m(-2)h(-1). Whereas the oxidation potential was strongly diminished in the bare control column filled with clayey silt even at low CH(4)-loads. By contrast the planted clayey silt showed an increased methane oxidation potential compared to the bare column. The spreading root system forms secondary macro-pores, and hence amplifies the air diffusivity and sustain the oxygen supply to the methanotrophic bacteria. Water is produced during methane oxidation, causing leachate. Vegetation reduces the leachate by evapotranspiration. Furthermore, leguminous plants support the enrichment of soil with nitrogen compounds and thus improving the methane oxidation process. In conclusion, vegetation is relevant for the increase of oxygen diffusion into the soil and subsequently enhances effective methane oxidation in landfill cover soils. PMID:21169005

Bohn, Sonja; Brunke, Paul; Gebert, Julia; Jager, Johannes

2011-05-01

175

Soil seed bank of the waste landfills in South Korea  

Microsoft Academic Search

The restoration of urban landfill is a topic of growing interest in reclamation ecology as the acreage of abandoned sites near cities increases. The goals of this study were to assess the ecological status of waste landfills and to elucidate the role of seed banks in the establishment of vegetation at these sites. The study sites were located at five

Kee Dae Kim; Eun Ju Lee

2005-01-01

176

Soil-gas contamination and entry of volatile organic compounds into a house near a landfill  

SciTech Connect

Toxic volatile organic compounds (VOC) are commonly found in landfills, including those accepting only municipal waste. These VOC can migrate away from the site through the soil and result in contaminated off-site soil gas. This contaminated soil gas can enter houses built near landfills and is a potential source of human exposure to VOC. This study investigated soil-gas contamination and the mechanisms of entry of VOC into a house with a basement sited adjacent to a municipal landfill. The VOC were identified and quantified in the soil gas and in indoor and outdoor air. Pressure coupling between the basement and the surrounding soil was measured. Using soil-gas tracers, the pressure-driven advective entry of soil gas was quantified as a function of basement depressurization. From the measurements, estimates were made for the diffusive and advective entry rates of VOC into the house. A comparison of the chlorinated hydrocarbons found in soil gas at the site and in the landfill suggests that the landfill is the source of the halogenated compounds in the vicinity of the house. At the conditions of the study, the diffusive and advective entry rates of VOC from soil into the basement were estimated to be low and of similar magnitude. Advective entry of soil gas into the house was limited by the low soil air permeability and the low below-grade leakage area of the basement. For this reason, high indoor concentrations due to the intrusion of VOC from soil gas are unlikely at this house, even under conditions that would produce relatively large underpressures in the basement.

Hodgson, A.T.; Garbesi, K.; Sextro, R.G.; Daisey, J.M. (Lawrence Berkeley Lab., CA (United States))

1992-03-01

177

Consuming un-captured methane from landfill using aged refuse bio-cover.  

PubMed

A novel simulated bio-cover was developed to facilitate the biological methane oxidation process using aged refuse and aged sludge from landfill. It was found that 78.7% and 66.9% of CH(4) could be removed, with the aged refuse: aged sludge (w/w%) ratio of 7:3 and 6:4 in bio-cover system, respectively. The maximum CH(4) removal rate could reach 100%, when the aged refuse with the disposal time more than 14 years were applied in bio-cover. Some controlled factors for the methanotrophic activity, i.e. moisture, Eh and organic matter content, were also investigated. It was found that CH(4) oxidation rate increased greatly, when the moisture content and organic matter were increased from 6.0%, 4.8% to 8.0%, 9.5%, respectively. The optimum conditions for this bio-cover system was found to be as follows: aged refuse: aged sludge ratio of 7:3, the moisture content of 8-9%, Eh of 104-108 mV and organic matter of 9.5%. PMID:21078552

Lou, Ziyang; Wang, Li; Zhao, Youcai

2011-02-01

178

Operational Costs of Applying Daily Cover Material at Sanitary Landfills in North Carolina.  

National Technical Information Service (NTIS)

Daily operations at sanitary landfills constitute a significant expense for the many local governmental units that own and operate them. Several trends effect this expense, and all are contributing to escalating landfill costs. The first trend is toward m...

G. Emanuel

1988-01-01

179

Establishment of a landfill impact zone on soils using structural and functional modifications of microbial communities  

Microsoft Academic Search

A number of structural and functional parameters of microbial communities have been applied for ecological monitoring of soils\\u000a located in nearby landfills. The difference in sensitivities to pollution between different microbial indices was shown. A\\u000a landfill impact zone in the direction of pollution migration was established using the total disturbance index of habitat\\u000a microbial communities.

T. O. Poputnikova; V. A. Terekhova

2010-01-01

180

LEACHATE CLOGGING ASSESSMENT OF GEOTEXTILE AND SOIL LANDFILL FILTERS  

EPA Science Inventory

The liquids management strategy for any municipal or hazardous waste landfill requires a knowledgeable design strategy for the leachate collection system located at the base of the waste mass. Such leachate collection systems generally consist of sumps, perforated pipes, drainag...

181

Soil contamination by heavy metals in landfills: measurements from an unlined leachate storage basin.  

PubMed

Landfills are sources of groundwater and soil pollution due to the production of leachate and its migration through refuse. This study was conducted in order to determine the extent of soil pollution within and around the Jebel Chakir landfill, located in the Tunis City, Tunisia. The main objective was to characterize soil samples of an unlined storage basin in relation to heavy metal concentrations in the Jebel Chakir landfill to the southwest of Tunis, Northern Tunisia. Twenty-four soil samples taken from different locations around the storage basin were analyzed by atomic absorption spectrophotometry for Cr, Cu, Ni, Pb, and Zn investigation. Our results indicated high concentrations of Cr (54.4-129.9 mg/kg of DM), Zn (4.1-81.8 mg/kg of DM), Ni (15.1-43.9 mg/kg of DM), Pb (5.6-16.1 mg/kg of DM), and Cu (0.2-1.84 mg/kg of DM). These results suggested that contaminant migration is controlled by an active clay layer acting as an insulating material in the landfill. It is therefore necessary to set a treatment system for the landfill leachates and place a liner under the storage basin to reduce the pollution threat. PMID:24723123

Bouzayani, Fethi; Aydi, Abdelwaheb; Abichou, Tarek

2014-08-01

182

Remote sensing of crop residue cover and soil tillage intensity  

Microsoft Academic Search

Management of plant litter or crop residues in agricultural fields is an important consideration for reducing soil erosion and increasing soil organic C. Current methods of quantifying crop residue cover are inadequate for characterizing the spatial variability of residue cover within fields or across large regions. Our objectives were to evaluate several spectral indices for measuring crop residue cover using

C. S. T. Daughtry; P. C. Doraiswamy; E HUNTJR; A. J. Stern; J MCMURTREYIII; J. H. Prueger

2006-01-01

183

Effects of compost biocovers on gas flow and methane oxidation in a landfill cover.  

PubMed

Previous publications described the performance of biocovers constructed with a compost layer placed on select areas of a landfill surface characterized by high emissions from March 2004 to April 2005. The biocovers reduced CH(4) emissions 10-fold by hydration of underlying clay soils, thus reducing the overall amount of CH(4) entering them from below, and by oxidation of a greater portion of that CH(4). This paper examines in detail the field observations made on a control cell and a biocover cell from January 1, 2005 to December 31, 2005. Field observations were coupled to a numerical model to contrast the transport and attenuation of CH(4) emissions from these two cells. The model partitioned the biocover's attenuation of CH(4) emission into blockage of landfill gas flow from the underlying waste and from biological oxidation of CH(4). Model inputs were daily water content and temperature collected at different depths using thermocouples and calibrated TDR probes. Simulations of CH(4) transport through the two soil columns depicted lower CH(4) emissions from the biocover relative to the control. Simulated CH(4) emissions averaged 0.0gm(-2)d(-1) in the biocover and 10.25gm(-2)d(-1) in the control, while measured values averaged 0.04gm(-2)d(-1) in the biocover and 14gm(-2)d(-1) in the control. The simulated influx of CH(4) into the biocover (2.7gm(-2)d(-1)) was lower than the simulated value passing into the control cell (29.4gm(-2)d(-1)), confirming that lower emissions from the biocover were caused by blockage of the gas stream. The simulated average rate of biological oxidation predicted by the model was 19.2gm(-2)d(-1) for the control cell as compared to 2.7gm(-2)d(-1) biocover. Even though its V(max) was significantly greater, the biocover oxidized less CH(4) than the control cell because less CH(4) was supplied to it. PMID:19131233

Abichou, Tarek; Mahieu, Koenraad; Yuan, Lei; Chanton, Jeffery; Hater, Gary

2009-05-01

184

About soil cover heterogeneity of agricultural research stations' experimental fields  

NASA Astrophysics Data System (ADS)

Depending on local pedo-ecological conditions (topography, (geo) diversity of soil parent material, meteorological conditions) the patterns of soil cover and plant cover determined by soils are very diverse. Formed in the course of soil-plant mutual relationship, the natural ecosystems are always influenced to certain extent by the other local soil forming conditions or they are site specific. The agricultural land use or the formation of agro-ecosystems depends foremost on the suitability of soils for the cultivation of feed and food crops. As a rule, the most fertile or the best soils of the area, which do not present any or present as little as possible constraints for agricultural land use, are selected for this purpose. Compared with conventional field soils, the requirements for the experimental fields' soil cover quality are much higher. Experimental area soils and soil cover composition should correspond to local pedo-ecological conditions and, in addition to that, represent the soil types dominating in the region, whereas the fields should be as homogeneous as possible. The soil cover heterogeneity of seven arable land blocks of three research stations (Jõgeva, Kuusiku and Olustvere) was studied 1) by examining the large scale (1:10 000) digital soil map (available via the internet), and 2) by field researches using the transect method. The stages of soils litho-genetic and moisture heterogeneities were estimated by using the Estonian normal soils matrix, however, the heterogeneity of top- and subsoil texture by using the soil texture matrix. The quality and variability of experimental fields' soils humus status, was studied more thoroughly from the aspect of humus concentration (g kg-1), humus cover thickness (cm) and humus stocks (Mg ha-1). The soil cover of Jõgeva experimental area, which presents an accumulative drumlin landscape (formed during the last glacial period), consist from loamy Luvisols and associated to this Cambisols. In Kuusiku area, which landscape is characterized by till and limestone plains with thin Quaternary cover, the soil cover is more heterogeneous than in previous area. Kuusiku soil cover is more variegated by the soil texture and as well as by the genesis of soils. In addition to Cambisols, Leptosols, Gleysols and Luvisols may be found here as well. The dominating soils in Olustvere research area, which is situated on wavy upland plateau, are Albeluvisols.

Rannik, Kaire; Kõlli, Raimo; Kukk, Liia

2013-04-01

185

Remote sensing of crop residue cover and soil tillage intensity  

Microsoft Academic Search

Crop residues on the soil surface reduce soil erosion and affect water infiltration, evaporation, and soil temperatures. Crop residues also influence the flow of nutrients, carbon, water, and energy in agricultural ecosystems. Current methods of measuring crop residue cover are inadequate for monitoring large areas. One promising remote sensing approach for discriminating crop residues from soil is based on a

C. S. T. Daughtry; P. C. Doraiswamy; A. L. Russ

2003-01-01

186

The controlling of landfill leachate evapotranspiration from soil-plant systems with willow: Salix amygdalina L.  

PubMed

The use of willows (Salix amygdalina L) to manage landfill leachate disposal is an effective and cost-effective method due to the high transpiration ability of the willow plants. A 2-year lysimetric experiment was performed to determine an optimum leachate hydraulic loading rate to achieve high evapotranspiration but exert no harmful influence on the plants. The evapotranspiration rate of a soil-plant system planted with the willow was 1.28-5.12-fold higher than the rate measured on a soil surface lacking vegetation, suggesting that soil-willow systems with high volatilization rates are a viable landfill leachate treatment method. Of the soil-willow systems, the one with willow growing on sand amended with sewage sludge soil at an hydraulic loading rate of 1 mm day(-1) performed best, with evapotranspiration ranging from 2.25 to 3.02 mm day(-1) and a biomass yield of 8.0-9.85 Mg dry matter ha(-1). The organic fraction of the soil increased as much as 2.5% of dry matter, due to the sewage sludge input, which exerted a positive effect on the biomass yield as well as on transpiration and evaporation. It was observed that the plants in the sand-and-sewage sludge soil systems displayed higher resistance to toxic effects from the applied landfill leachate relative to plants in the sand-soil systems. PMID:17346008

Bia?owiec, Andrzej; Wojnowska-Bary?a, Irena; Hasso-Agopsowicz, Marek

2007-02-01

187

LEACHATE CLOGGING ASSESSMENT OF GEOTEXTILE AND SOIL LANDFILL FILTERS  

EPA Science Inventory

This project was focused on the performance, design, testing and selection of filters used for leachate collection drains at the base of landfills, waste piles and other solid waste facilities. Geotextiles due to their manufactured uniformity, ease-of placement and savings in lan...

188

Treatment of landfill leachate by using lateritic soil as a natural coagulant.  

PubMed

In this research, the capability of lateritic soil used as coagulant for the treatment of stabilized leachate from the Penang-Malaysia Landfill Site was investigated. The evaluation of lateritic soil coagulant in comparison with commercialized chemical coagulants, such as alum, was performed using conventional jar test experiments. The optimum pH and coagulant dosage were identified for the lateritic soil coagulant and the comparative alum coagulant. It was found that the application of lateritic soil coagulant was quite efficient in the removal of COD, color and ammoniacal-nitrogen content from the landfill leachate. The optimal pH value was 2.0, while 14 g/L of lateritic soil coagulant was sufficient in removing 65.7% COD, 81.8% color and 41.2% ammoniacal-nitrogen. Conversely, the optimal pH and coagulant dosage for the alum were pH 4.8 and 10 g/L respectively, where 85.4% COD, 96.4% color and 47.6% ammoniacal-nitrogen were removed from the same leachate sample. Additionally, the Sludge Volume Index (SVI) ratio of alum and lateritic soil coagulant was 53:1, which indicated that less sludge was produced and was an environmentally friendly product. Therefore, lateritic soil coagulant can be considered a viable alternative in the treatment of landfill leachate. PMID:22964042

Syafalni; Lim, Han Khim; Ismail, Norli; Abustan, Ismail; Murshed, Mohamad Fared; Ahmad, Anees

2012-12-15

189

Methanotroph diversity in landfill soil: Isolation of novel type I and type II methanotrophs whose presence was suggested by culture-independent 16S ribosomal DNA analysis  

Microsoft Academic Search

The diversity of the methanotrophic community in mildly acidic landfill cover soil was assessed by three methods: two culture-independent molecular approaches and a traditional culture-based approach. For the first of the molecular studies, two primer pairs specific for the 16S rRNA gene of validly published type I (including for former type X) and type II methanotrophs were identified and tested.

MARK G. WISE; J VAUN MCARTHUR; L. J. Smimkets

1999-01-01

190

Soil cover of gas-bearing areas  

NASA Astrophysics Data System (ADS)

Natural soils with disturbed functioning parameters compared to the background soils with conservative technogenic-pedogenic features were distinguished on vast areas above the artificial underground gas storages in the zones of spreading and predominant impact of hydrocarbon gases. The disturbance of the functioning parameters is related to the increase in the methane concentration, the bacterial oxidation intensity and destruction, and the complex microbiological and physicochemical synthesis of iron oxides. The technogenic-pedogenic features include neoformations of bacteriomorphic microdispersed iron oxides. The impurity components consist of elements typical for biogenic structures. New soil layers, horizons, specific anthropogenically modified soils, and soil-like structures were formed on small areas in the industrial zones of underground gas storages due to the mechanical disturbance, the deposition of drilling sludge, and the chemical contamination. Among the soils, postlithogenic formations were identified—chemotechnosols (soddy-podzolic soils and chernozems), as well as synlithogenic ones: strato-chemotechnosols and stratochemoembryozems. The soil-like bodies included postlithogenic soil-like structures (chemotechnozems) and synlithogenic ones (strato-chemotechnozems). A substantive approach was used for the soil diagnostics. The morphological and magnetic profiles and the physical, chemical, and physicochemical properties of the soils were analyzed. The micromorphological composition of the soil magnetic fraction was used as a magnetic label.

Mozharova, N. V.

2010-08-01

191

Quantifying the effect of oxidation on landfill methane emissions  

Microsoft Academic Search

Field, laboratory, and computer modeling methods were utilized to quantitatively assess the capability of aerobic microorganisms to oxidize landfill-derived methane (CH4) in cover soils. The investigated municipal landfill, located in Nashua, New Hampshire, was operating without gas controls of any type at the time of sample collection. Soil samples from locations of CH 4 flux to the atmosphere were returned

P. M. Czepiel; B. Mosher; P. M. Crill; R. C. Harriss

1996-01-01

192

Methane oxidation in a boreal climate in an experimental landfill cover composed from mechanically–biologically treated waste  

Microsoft Academic Search

The present study evaluated microbial methane (CH4) oxidation in a boreally located outdoor landfill lysimeter (volume 112 m3, height 3.9 m) filled with mechanically–biologically treated waste (MBT residual) and containing a cover layer made from the same MBT residual. The calculations based on gas emission and pore gas measurements showed that, between April and October 2005, a significant proportion (>96%) of the

J.-K. M. Einola; K. M. Sormunen; J. A. Rintala

2008-01-01

193

Radon diffusion in candidate soils for covering uranium mill tailings  

Microsoft Academic Search

Diffusion coefficients were measured for radon in 34 soils that had been identified by mill personnel as candidate covers for their tailings piles in order to reduce radon emission. These coefficients referred to diffusion in the total pore space of the soils. They were measured in the laboratory by a steady-state method using soil columns compacted to greater than 80%

W. B. Silker; D. R. Kalkwarf

1983-01-01

194

Evolution of the soil cover of soccer fields  

NASA Astrophysics Data System (ADS)

A soccer field can be considered a soil-like technogenic formation (STF). According to the theory of soil cover patterns, the artificially constructed (anthropogenic) soil cover of a soccer field is an analogue of a relatively homogeneous elementary soil area. However, the spatial homogeneity of the upper part (50-80 cm) of the STF of soccer fields is unstable and is subjected to gradual transformation under the impact of pedogenetic processes, agrotechnical loads, and mechanical loads during the games. This transformation is favored by the initial heterogeneity of the deep (buried) parts of the STF profile. The technogenic factors and elementary pedogenetic processes specify the dynamic functioning regime of the STF. In 50-75 years, the upper part of the STF is transformed into soil-like bodies with properties close to those in zonal soils. Certain micro- and nanopatterns of the soil cover are developed within the field creating its spatial heterogeneity.

Belobrov, V. P.; Zamotaev, I. V.

2014-04-01

195

Methane oxidation at a surface-sealed boreal landfill  

Microsoft Academic Search

Methane oxidation was studied at a closed boreal landfill (area 3.9ha, amount of deposited waste 200,000 tonnes) equipped with a passive gas collection and distribution system and a methane oxidative top soil cover integrated in a European Union landfill directive-compliant, multilayer final cover. Gas wells and distribution pipes with valves were installed to direct landfill gas through the water impermeable

Juha Einola; Kai Sormunen; Anssi Lensu; Antti Leiskallio; Matti Ettala; Jukka Rintala

2009-01-01

196

Effects of ammonium on the activity and community of methanotrophs in landfill biocover soils.  

PubMed

The influence of NH4(+) on microbial CH4 oxidation is still poorly understood in landfill cover soils. In this study, effects of NH4(+) addition on the activity and community structure of methanotrophs were investigated in waste biocover soil (WBS) treated by a series of NH4(+)-N contents (0, 100, 300, 600 and 1200mgkg(-1)). The results showed that the addition of NH4(+)-N ranging from 100 to 300mgkg(-1) could stimulate CH4 oxidation in the WBS samples at the first stage of activity, while the addition of an NH4(+)-N content of 600mgkg(-1) had an inhibitory effect on CH4 oxidation in the first 4 days. The decrease of CH4 oxidation rate observed in the last stage of activity could be caused by nitrogen limitation and/or exopolymeric substance accumulation. Type I methanotrophs Methylocaldum and Methylobacter, and type II methanotrophs (Methylocystis and Methylosinus) were abundant in the WBS samples. Of these, Methylocaldum was the main methanotroph in the original WBS. With incubation, a higher abundance of Methylobacter was observed in the treatments with NH4(+)-N contents greater than 300mgkg(-1), which suggested that NH4(+)-N addition might lead to the dominance of Methylobacter in the WBS samples. Compared to type I methanotrophs, the abundance of type II methanotrophs Methylocystis and/or Methylosinus was lower in the original WBS sample. An increase in the abundance of Methylocystis and/or Methylosinus occurred in the last stage of activity, and was likely due to a nitrogen limitation condition. Redundancy analysis showed that NH4(+)-N and the C/N ratio had a significant influence on the methanotrophic community in the WBS sample. PMID:24794017

Zhang, Xuan; Kong, Jiao-Yan; Xia, Fang-Fang; Su, Yao; He, Ruo

2014-06-01

197

Study of Some Puerto Rican Soils as Natural Sealers or Attenuators Against Groundwater Pollution from Sanitary Landfill Leachates.  

National Technical Information Service (NTIS)

Five clayey Puerto Rican soils were packed into columns of PVC pipe and tested for their ability to prevent groundwater pollution from the Mayaguez sanitary landfill. Leachate and groundwater samples collected from column effluents were analyzed for water...

L. A. del Valle

1983-01-01

198

Evaluation of engineering properties for the use of leached brown coal ash in soil covers.  

PubMed

The need to engineer cover systems for the successful rehabilitation or remediation of a wide variety of solid wastes is increasing. Some common applications include landfills, hazardous waste repositories, or mine tailings dams and waste rock/overburden dumps. The brown coal industry of the Latrobe Valley region of Victoria, Australia, produces significant quantities of coal ash and overburden annually. There are some site-specific acid mine drainage (AMD) issues associated with overburden material. This needs to be addressed both during the operational phase of a project and during rehabilitation. An innovative approach was taken to investigate the potential to use leached brown coal ash in engineered soil covers on this overburden dump. The basis for this is two-fold: first, the ash has favourable physical characteristics for use in cover systems (such as high storage capacity/porosity, moderately low permeability, and an ability to act as a capillary break layer generating minimal leachate or seepage); and second, the leachate from the ash is mildly alkaline (which can help to mitigate and reduce the risk of AMD). This paper will review the engineering issues involved in using leached brown coal ash in designing soil covers for potentially acid-forming overburden dumps. It presents the results of laboratory work investigating the technical feasibility of using leached brown coal ash in engineered solid waste cover systems. PMID:16621267

Mudd, Gavin M; Chakrabarti, Srijib; Kodikara, Jayantha

2007-01-31

199

Soil cover by natural trees in agroforestry systems  

NASA Astrophysics Data System (ADS)

The dehesa is common agroforestry system in the Iberian Peninsula. These open oak parklands with silvo-pastoral use cover about two million hectares. Traditionally annual pastures have been grazed by cows, sheep and also goats while acorns feed Iberian pig diet. Evergreen oak (Quercus ilex L.) has other uses as fuelwood collection and folder after tree pruning. The hypothesis of this work is that tree density and canopy depend on soil types. We using the spanish GIS called SIGPAC to download the images of dehesa in areas with different soil types. True colour images were restoring to a binary code, previously canopy colour range was selected. Soil cover by tree canopy was calculated and number of trees. Processing result was comparable to real data. With these data we have applied a dynamic simulation model Dehesa to determine evergreen oak acorn and annual pasture production. The model Dehesa is divided into five submodels: Climate, Soil, Evergreen oak, Pasture and Grazing. The first three require the inputs: (i) daily weather data (maximum and minimum temperatures, precipitation and solar radiation); (ii) the soil input parameters for three horizons (thickness, field capacity, permanent wilting point, and bulk density); and (iii) the tree characterization of the dehesa (tree density, canopy diameter and height, and diameter of the trunk). The influence of tree on pasture potential production is inversely proportional to the canopy cover. Acorn production increase with tree canopy cover until stabilizing itself, and will decrease if density becomes too high (more than 80% soil tree cover) at that point there is competition between the trees. Main driving force for dehesa productivity is soil type for pasture, and tree cover for acorn production. Highest pasture productivity was obtained on soil Dystric Planosol (Alfisol), Dystric Cambisol and Chromo-calcic-luvisol, these soils only cover 22.4% of southwest of the Iberian peninssula. Lowest productivity was obtained on Dystric Lithosol.

Diaz-Ambrona, C. G. H.; Almoguera Millán, C.; Tarquis Alfonso, A.

2009-04-01

200

INVESTIGATION OF LANDFILL LEACHATE POLLUTANT ATTENUATION BY SOILS  

EPA Science Inventory

In this laboratory study using 11 soils from 7 major orders in the U.S., the movement and retention of As, Be, Cd, CN, Cr, Cu, Hg, Ni, Pb, Se, V, and Zn when carried by municipal solid waste (MSW) leachate through soils was influenced by the individual properties of the elements,...

201

Influence of cover crops and soil amendments on okra (Abelmoschus esculentus L.) production and soil nematodes  

Microsoft Academic Search

A pot experiment to determine the effects of summer cover crops and soil amendments on okra yields and population densities of various soil nematode taxa was conducted in two consecutive growing seasons in a subtropical region. Two cover crops, sunn hemp (Crotalaria juncea) and sorghum sudangrass (Sorghum bicolorrS. bicolor var. sudanense), were grown and returned to the soil with fallow

Qingren Wang; Yuncong Li; Waldemar Klassen; Zafar Handoo

2007-01-01

202

Nitrogen Mineralization of Cover Crop Residues in Calcareous Gravelly Soil  

Microsoft Academic Search

Tropical legumes like sunn hemp (Crotolaria juncea L.) and aeschynomene (Aeschynomene evenia L.) have potential as alternative cover crops in tropical regions. The objective of this study was to evaluate the N mineralization rates of three cover crops [aeschynomene (AE), sorghum sudangrass (Sorghum sudanense L.), and sunn hemp (SH)] residues used to amend a calcareous gravelly soil in order to

R. B. Rao; Y. C. Li

2003-01-01

203

Passive and active soil gas sampling at the Mixed Waste Landfill, Technical Area III, Sandia National Laboratories/New Mexico  

SciTech Connect

The Environmental Restoration Project at Sandia National Laboratories, New Mexico is tasked with assessing and remediating the Mixed Waste Landfill in Technical Area III. The Mixed Waste Landfill is a 2.6 acre, inactive radioactive and mixed waste disposal site. In 1993 and 1994, an extensive passive and active soil gas sampling program was undertaken to identify and quantify volatile organic compounds in the subsurface at the landfill. Passive soil gas surveys identified levels of PCE, TCE, 1,1, 1-TCA, toluene, 1,1,2-trichlorotrifluoroethane, dichloroethyne, and acetone above background. Verification by active soil gas sampling confirmed concentrations of PCE, TCE, 1,1,1-TCA, and 1,1,2-trichloro-1,2,2-trifluoroethane at depths of 10 and 30 feet below ground surface. In addition, dichlorodifluoroethane and trichlorofluoromethane were detected during active soil gas sampling. All of the volatile organic compounds detected during the active soil gas survey were present in the low ppb range.

McVey, M.D.; Goering, T.J. [GRAM, Inc., Albuquerque, NM (United States); Peace, J.L. [Sandia National Labs., Albuquerque, NM (United States)

1996-02-01

204

Microwave Backscatter Dependence on Surface Roughness, Soil Moisture, and Soil Texture: Part II-Vegetation-Covered Soil  

Microsoft Academic Search

Results are presented of an experimental investigation to determine the relationship between radar backscatter coefficient ¿° and soil moisture for vegetation-covered soil. These results extend a previous report which showed the experimental relationship between ¿° and soil moisture for bare soil [1]. It is shown that the highest correlation between ¿° and soil moisture is 0.92 for the combined response

Fawwaz Ulaby; Gerald Bradley; Myron Dobson

1979-01-01

205

Monitoring the Performance of an Alternative Landfill Cover at the Monticello, Utah, Uranium Mill Tailings Disposal Site  

SciTech Connect

The U.S. Department of Energy Office of Legacy Management (DOE) and the U.S. Environmental Protection Agency (EPA) collaborated on the design and monitoring of an alternative cover for the Monticello uranium mill tailings disposal cell, a Superfund site in southeastern Utah. Ground-water recharge is naturally limited at sites like Monticello where thick, fine-textured soils store precipitation until evaporation and plant transpiration seasonally return it to the atmosphere. The cover at Monticello uses local soils and a native plant community to mimic the natural soil water balance. The cover is fundamentally an evapotranspiration (ET) design with a capillary barrier. A 3-hectare drainage lysimeter was embedded in the cover during construction of the disposal cell in 2000. The lysimeter consists of a geo-membrane liner below the capillary barrier that directs percolation water to a monitoring system. Soil water storage is determined by integration of point water content measurements. Meteorological parameters are measured nearby. Plant cover, shrub density, and leaf area index (LAI) are monitored annually. The cover performed well over the 7-year monitoring period (2000-2007). The cumulative percolation was 4.2 mm (0.6 mm yr{sup -1}), satisfying an EPA goal of an average percolation of <3.0 mm yr{sup -1}. Almost all percolation can be attributed to the exceptionally wet winter and spring of 2004-2005 when soil water content slightly exceeded the water storage capacity of the cover. The diversity, percent cover, and LAI of vegetation increased over the monitoring period, although the density of native shrubs that extract water from deeper in the cover has remained less than revegetation targets. DOE and EPA are applying the monitoring results to plan for long-term surveillance and maintenance and to evaluate alternative cover designs for other waste disposal sites. (authors)

Waugh, W.J.; Kastens, M.K.; Sheader, L.R.L. [Environmental Sciences Laboratory, Grand Junction, CO (United States); Benson, C.H. [University of Wisconsin, Madison, WI (United States); Albright, W.H. [Desert Research Institute, Reno, NV (United States); Mushovic, P.S. [U.S. Environmental Protection Agency, Denver, CO (United States)

2008-07-01

206

Performance of multi-soil-layering system (MSL) treating leachate from rural unsanitary landfills.  

PubMed

The widely spread rural unsanitary landfills in South China pose an environmental threat to water bodies and soil. Although various processing technologies have been utilized for treatment of landfill leachate, their application to the landfills in rural areas is restricted by the availability of skilled professionals and high operation costs. In this experiment, four MSLs with altered soil mixed block (SMB) and different hydraulic load rate (HLR) were applied in the experiment to investigate the treatment of the landfill leachate without aeration or under low aeration supply. The experiment results showed that the improved MSL could effectively treat the chemical oxygen demand (COD), NH(4)-N and P. COD and NH(4)-N removal efficiencies of MSL were 97.4%, 82.4% and 72.0%, 62.0%, respectively under HLRs of 200 and 400L/(m(2)·d) without aeration; COD and NH(4)-N removal efficiencies of M800 and M1600 were 62.3%, 53.4% and 45.3%, 35.3% respectively under intermittent aeration. N removal efficiency was low due to a strong nitrification effect, and the nitrogen removal capacity of the MSL was greatly reduced at the end of the experiment. P removal efficiency of MSL was 75.6 to 91.9% under HLR 200 and 400L/(m(2)·d). The intermittent aeration was helpful to remove the clogging of MSLs, after they were clogged under HLRs of 800 and 1600L/(m(2)·d). MSL is promising as an appealing nitrifying biofilm reactor. PMID:22326312

Yidong, Guan; Xin, Chen; Shuai, Zhang; Ancheng, Luo

2012-03-15

207

Assessment of soil-gas, soil, and water contamination at the former hospital landfill, Fort Gordon, Georgia, 2009-2010  

USGS Publications Warehouse

Soil gas, soil, and water were assessed for organic and inorganic constituents at the former hospital landfill located in a 75-acre study area near the Dwight D. Eisenhower Army Medical Center, Fort Gordon, Georgia, from April to September 2010. Passive soil-gas samplers were analyzed to evaluate organic constituents in the hyporheic zone of a creek adjacent to the landfill and soil gas within the estimated boundaries of the former landfill. Soil and water samples were analyzed to evaluate inorganic constituents in soil samples, and organic and inorganic constituents in the surface water of a creek adjacent to the landfill, respectively. This assessment was conducted to provide environmental constituent data to Fort Gordon pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Results from the hyporheic-zone assessment in the unnamed tributary adjacent to the study area indicated that total petroleum hydrocarbons and octane were the most frequently detected organic compounds in groundwater beneath the creek bed. The highest concentrations for these compounds were detected in the upstream samplers of the hyporheic-zone study area. The effort to delineate landfill activity in the study area focused on the western 14 acres of the 75-acre study area where the hyporheic-zone study identified the highest concentrations of organic compounds. This also is the part of the study area where a debris field also was identified in the southern part of the 14 acres. The southern part of this 14-acre study area, including the debris field, is steeper and not as heavily wooded, compared to the central and northern parts. Fifty-two soil-gas samplers were used for the July 2010 soil-gas survey in the 14-acre study area and mostly detected total petroleum hydrocarbons, and gasoline and diesel compounds. The highest soil-gas masses for total petroleum hydrocarbons, diesel compounds, and the only valid detection of perchloroethene were in the southern part of the study area to the west of the debris field. However, all other detections of total petroleum hydrocarbons greater than 10 micrograms and diesel greater than 0.04 micrograms, and all detections of the combined mass of benzene, toluene, ethylbenzene, and xylene were found down slope from the debris field in the central and northern parts of the study area. Five soil-gas samplers were deployed and recovered from September 16 to 22, 2010, and were analyzed for organic compounds classified as chemical agents or explosives. Chloroacetophenones (a tear gas component) were the only compounds detected above a method detection level and were detected at the same location as the highest total petroleum hydrocarbons and diesel detections in the southern part of the 14-acre study area. Composite soil samples collected at five locations were analyzed for 35 inorganic constituents. None of the inorganic constituents exceeded the regional screening levels. One surface-water sample collected in the western end of the hyporheic-zone study area had a trichlorofluoromethane concentration above the laboratory reporting level and estimated concentrations of chloroform, fluoranthene, and isophorone below laboratory reporting levels.

Falls, Fred W.; Caldwell, Andral W.; Guimaraes, Wladmir B.; Ratliff, W. Hagan; Wellborn, John B.; Landmeyer, James E.

2011-01-01

208

Prediction of the water balance of two soil cover systems  

Microsoft Academic Search

Soil cover systems are widely used for containment of municipal solid waste, hazardous and mine waste, with the objective\\u000a of limiting the ingress of precipitation and oxygen. The ability to predict their long-term performance is crucial, as their\\u000a failure would result in the release of contaminants to the environment. However, monitoring covers over the long term to derive\\u000a the information

Celestina Adu-Wusu; Ernest K. Yanful; Lisa Lanteigne; Mike O’Kane

2007-01-01

209

Promoting late-fall establishment of tall fescue with artificial soil covers to minimise soil erosion.  

PubMed

Frequently, turfgrass seedings have been sown in the late fall, which usually results in a poor vegetative stand and the possibility of soil erosion the following spring. This study evaluates the effects of a spun-bonded polyester soil cover placed over a late-fall seeding on subsequent seedling growth and overwintering. Clemfine, Mustang, Rebel, and Rebel II cultivars of tall fescue (Festuca arundinacea Schreb.) were sown on a silt loam soil in late fall (on 17 October in 1989 and 19 October in 1990) and allowed to grow with and without a soil cover until June. In the spring the temperature under the soil cover was greater than 2°C warmer than the uncovered soil from mid-April through May. Over the winter, leaf and root weights showed no detrimental effects from being under the cover. Individual cultivars grown under the cover produced 2 to 11 times greater leaf yields and 38 to 270% better stand establishment than those sown on the exposed soil. However, plant winter injury was observed under the soil cover in small soil depressions which accumulated water originating from thawing. All cultivars had similar amounts of growth under the cover. However, leaf yields for Rebel were 30-55% less than the other cultivars when grown under the cover and this was probably related to a low seed germination rate. The covers also promoted weed growth, which comprised from 34-65% of total leaf weights and was found to be negatively correlated (r = -0.66) to the yields of the sown grass. The soil cover was found to be beneficial to improving the success of seedling establishment of late seedings of tall fescue in cold areas. PMID:24198171

Palazzo, A J

1994-03-01

210

Reduced sulfur compounds in gas from construction and demolition debris landfills  

Microsoft Academic Search

The biological conversion of sulfate from disposed gypsum drywall to hydrogen sulfide (H2S) in the anaerobic environment of a landfill results in odor problems and possible health concerns at many disposal facilities. To examine the extent and magnitude of such emissions, landfill gas samples from wells, soil vapor samples from the interface of the waste and cover soil, and ambient

Sue Lee; Qiyong Xu; Matthew Booth; Timothy G. Townsend; Paul Chadik; Gabriel Bitton

2006-01-01

211

Phytoextraction of As and Fe using Hibiscus cannabinus L. from soil polluted with landfill leachate.  

PubMed

Terrestrial plants as potential phytoremediators for remediation of surface soil contaminated with toxic metals have gained attention in clean-up technologies. The potential of kenaf (Hibiscus cannabinus L.) to offer a cost-effective mechanism to remediate Fe and As from landfill leachate-contaminated soil was investigated. Pot experiment employing soil polluted with treatments of Jeram landfill leachate was conducted for 120 days. Plants were harvested after 8th, 12th, and 16th weeks of growth. Accumulation of Fe and As was assessed based on Bioconcentration Factor and Translocation Factor. Results showed sequestration of 0.06-0.58 mg As and 66.82-461.71 mg Fe per g plant dry weight in kenaf root, which implies that kenaf root can be an bioavailable sink for toxic metals. Insignificant amount of Fe and As was observed in the aerial plant parts (< 12% of total bioavailable metals). The ability of kenaf to tolerate these metals and avoid phytotoxicity could be attributed to the stabilization of the metals in the roots and hence reduction of toxic metal mobility (TF < 1). With the application of leachate, kenaf was also found to have higher biomass and subsequently recorded 11% higher bioaccumulation capacity, indicating its suitability for phytoextraction of leachate contaminated sites. PMID:22567704

Meera, M; Agamuthu, P

2012-02-01

212

Reduction of Nitrate Leaching in Agricultural Soils via Cover Crops.  

National Technical Information Service (NTIS)

Field experiments on a Coastal Plain soil (Norfolk loamy sand) served as a basis for characterizing NO3 leaching potential and the subsequent potential of winter annual cover crops (crimson clover, rye, spring oat, wheat, and native weeds) to recover and ...

M. G. Wagger

1996-01-01

213

Landfill bioreactor design and operation  

SciTech Connect

Landfill Bioreactor Design and Operation covers the history and background of landfill technology, research studies of actual bioreactor landfills, expected leachate and gas yields, specific design criteria, operation guidelines, and reuse of landfill sites to avoid having to establish new sites. For anyone looking for an alternative to large, wasteful landfill sites, this book provides a practical alternative to the problem.

Reinhart, D.R. [Univ. of Central Florida, Orlando, FL (United States); Townsend, T. [Univ. of Florida, Gainesville, FL (United States)

1998-12-31

214

Application and verification of the soil-ecological index for assessing soil cover patterns on plowlands  

NASA Astrophysics Data System (ADS)

The reformation of Russian agriculture and the development of landscape-adaptive agricultural systems have generated interest in the agroecological aspects of studying soil cover patterns. The qualitative evaluation of soil resources is necessary for objective comparison of their quality at the landscape, regional, and interregional levels. The applicability of the soil-ecological index (SEI) as an integral criterion for quality assessment of soils, soil associations, and soil cover patterns on the basis of a common all-Russia scale has been experimentally verified on test plots. This index can also be applied for assessing the degree of contrast in the soil cover. The analysis of different soil-climatic regions in the European part of Russia has shown that the SEI value is well correlated with the soil-climatic conditions. However, for a particular farm, the climatic component of the SEI becomes equal for all the fields. At the same time, the soil properties and geomorphic conditions limiting soil fertility are usually different for different soil combinations, and they become essential upon calculation of the SEI for the particular field. Feasibility of verification and correction of the calculated SEI on the basis of experimental data is shown. This makes it possible to find better-grounded decisions on the agrotechnologies applicable for a given field.

Bulgakov, D. S.; Sorokina, N. P.; Karmanov, I. I.; Avdeeva, T. N.; Savitskaya, N. V.; Gribov, V. V.

2013-11-01

215

Radon diffusion in candidate soils for covering uranium mill tailings  

SciTech Connect

Diffusion coefficients were measured for radon in 34 soils that had been identified by mill personnel as candidate covers for their tailings piles in order to reduce radon emission. These coefficients referred to diffusion in the total pore space of the soils. They were measured in the laboratory by a steady-state method using soil columns compacted to greater than 80% of their Proctor maximum packing densities but with moisture contents generally less than would be expected at a tailings site. An empirical equation was used to extrapolate measured coefficients to value expected at soil-moisture contents representative of tailings sites in the western United States. Extrapolated values for silty sands and clayey sands ranged from 0.004 to 0.06 cm/sup 2//s. Values for inorganic silts and clays ranged from 0.001 to 0.02 cm/sup 2//s.

Silker, W.B.; Kalkwarf, D.R.

1983-04-01

216

[Investigation of polarization characteristics of soil surface with low vegetation cover and different soil moisture].  

PubMed

Compared with the spectral detection method, polarization detection could obtain more information of the target. For example, the polarization detection could be applied to interpret the refractive index and the surface roughness of the object, or retrieve the soil moisture, etc. Polarization detection provides a new approach to quantitative retrieval of soil moisture, and this is very important in agriculture, hydrology, meteorology and ecology. The polarization characteristics of soil surface with low vegetation cover,which is a example of mixed pixel in remote sensing, were researched with experiments, and the relationship between the polarization characteristics and soil moisture was also explored. The results showed that the polarization characteristics of soil surface with low vegetation cover are mainly determined by the area of bare soil, and are strongly relevant with the soil moisture. For the results of experiments in this paper, the IDOLP of soil surface with low vegetation cover increased with increasing soil moisture when the viewing angle of instrument was between 20 degree and 60 degree, while the incident angle of light source was fixed at 40 degree. This paper offered a new method to retrieve moisture content of soil with low vegetation cover. PMID:21284189

Zhang, Qiao; Sun, Xiao-bing; Hong, Jin

2010-11-01

217

Evaporative losses from soils covered by physical and different types of biological soil crusts  

USGS Publications Warehouse

Evaporation of soil moisture is one of the most important processes affecting water availability in semiarid ecosystems. Biological soil crusts, which are widely distributed ground cover in these ecosystems, play a recognized role on water processes. Where they roughen surfaces, water residence time and thus infiltration can be greatly enhanced, whereas their ability to clog soil pores or cap the soil surface when wetted can greatly decrease infiltration rate, thus affecting evaporative losses. In this work, we compared evaporation in soils covered by physical crusts, biological crusts in different developmental stages and in the soils underlying the different biological crust types. Our results show that during the time of the highest evaporation (Day 1), there was no difference among any of the crust types or the soils underlying them. On Day 2, when soil moisture was moderately low (11%), evaporation was slightly higher in well-developed biological soil crusts than in physical or poorly developed biological soil crusts. However, crust removal did not cause significant changes in evaporation compared with the respective soil crust type. These results suggest that the small differences we observed in evaporation among crust types could be caused by differences in the properties of the soil underneath the biological crusts. At low soil moisture (<6%), there was no difference in evaporation among crust types or the underlying soils. Water loss for the complete evaporative cycle (from saturation to dry soil) was similar in both crusted and scraped soils. Therefore, we conclude that for the specific crust and soil types tested, the presence or the type of biological soil crust did not greatly modify evaporation with respect to physical crusts or scraped soils.

Chamizo, S.; Cantón, Y.; Domingo, F.; Belnap, J.

2013-01-01

218

Sanitary Landfill. A Bibliography.  

National Technical Information Service (NTIS)

A bibliography on sanitary landfills is presented for the period 1925 - 1968, covering such materials as garbage and refuse disposal, ground water contamination, loading and structural properties, urban and rural sites, landfill internal mechanics, collec...

R. L. Steiner R. Kantz

1968-01-01

219

Transient soil moisture profile of a water-shedding soil cover in north Queensland, Australia  

NASA Astrophysics Data System (ADS)

In current agricultural and industrial applications, soil moisture determination is limited to point-wise measurements and remote sensing technologies. The former has limitations on spatial resolution while the latter, although has greater coverage in three dimensions, but may not be representative of real-time hydrologic conditions of the substrate. This conference paper discusses the use of elongated soil moisture probes to describe the transient soil moisture profile of water-shedding soil cover trial plots in north Queensland, Australia. Three-metre long flat ribbon cables were installed at designed depths across a soil cover with substrate materials from mining activities comprising of waste rocks and blended tailings. The soil moisture measurement is analysed using spatial time domain reflectometry (STDR) (Scheuermann et al., 2009) Calibration of the flat ribbon cable's soil moisture measurement in waste rocks is undertaken in a glasshouse setting. Soil moisture retention and outflows are monitored at specific time interval by mass balance and water potential measurements. These data sets together with the soil hydrologic properties derived from laboratory and field measurements are used as input in the numerical code on unsaturated flow, Hydrus2D. The soil moisture calculations of the glasshouse calibration using this numerical method are compared with results from the STDR soil moisture data sets. In context, the purpose of the soil cover is to isolate sulphide-rich mine wastes from atmospheric interaction as oxidation and leaching of these materials may result to acid and metalliferous drainage. The long term performance of a soil cover will be described in terms of the quantities and physico-chemical characteristics of its outflows. With the soil moisture probes set at automated and pre-determined measurement time intervals, it is expected to distinguish between macropore and soil moisture flows during high intensity rainfall events and, also continuously update data sets on soil moisture retention, especially during long periods of drought. As such, description of the soil cover water balance will be more elaborate as the soil moisture profile will be described in terms of temporal and spatial variability. Moreover, this field data set can lend support on the evaluation of the potential use of mine wastes as cover materials with respect to their hydrologic and geochemical properties.

Gonzales, Christopher; Baumgartl, Thomas; Scheuermann, Alexander

2014-05-01

220

The use of volcanic soil as mineral landfill liner--I. Physicochemical characterization and comparison with zeolites.  

PubMed

The main physicochemical characteristics of the volcanic soil of Southern Chile, with allophane as the main pedogenic mineral phase were analysed and compared with common zeolites (clinoptilolite) of the European market. The ultimate goal of this study was to test volcanic soil for the use as mineral landfill liner. The main results indicated that the clay and silt fractions together of the volcanic soil were between 38 and 54%. The buffering capacity of the volcanic soil was higher compared with the studied zeolites, whereas the cationic exchange capacity of the volcanic soil (between 5.2 and 6.5 cmol + kg(-1)) is of the same order of magnitude of the studied zeolites (between 9.7 and 11.4 cmol + kg(-1)). Moreover, the anionic exchange capacity of the volcanic soil was higher compared to the zeolites analysed. The hydraulic conductivity of the volcanic soil, measured in the laboratory at maximum proctor density, ranges between 5.16 x 10(-9) and 6.48 x 10(-9) m s(-1), a range that is comparable to the value of 4.51 x 10(-9) m s(-1) of the studied zeolite. The Proctor densities of the volcanic soil are in a lower range (between 1.11 and 1.15 g ml(-1)) compared with zeolites (between 1.19 and 1.34 g ml(-1)). The volcanic soil physicochemical characteristics are comparable to all the requirements established in the Austrian landfill directive (DVO, 2000). Therefore, the use as mineral landfill basal sealing of the analysed volcanic soil appears reasonable, having a pollutant adsorption capacity comparable to zeolites. It is of special interest for Southern Chile, because there are no alternative mineral raw materials for basal liners of landfills. PMID:15988944

Navia, Rodrigo; Hafner, Georg; Raber, Georg; Lorber, Karl E; Schöffmann, Elke; Vortisch, Walter

2005-06-01

221

Assessment of soil-gas and groundwater contamination at the Gibson Road landfill, Fort Gordon, Georgia, 2011  

USGS Publications Warehouse

Soil-gas and groundwater assessments were conducted at the Gibson Road landfill in 201 to provide screening-level environmental contamination data to supplement the data collected during previous environmental studies at the landfill. Passive samplers were used in both assessments to detect volatile and semivolatile organic compounds and polycyclic aromatic hydrocarbons in soil gas and groundwater. A total of 56 passive samplers were deployed in the soil in late July and early August for the soil-gas assessment. Total petroleum hydrocarbons (TPH) were detected at masses greater than the method detection level of 0.02 microgram in all samplers and masses greater than 2.0 micrograms in 13 samplers. Three samplers located between the landfill and a nearby wetland had TPH masses greater than 20 micrograms. Diesel was detected in 28 of the 56 soil-gas samplers. Undecane, tridecane, and pentadecane were detected, but undecane was the most common diesel compound with 23 detections. Only five detections exceeded a combined diesel mass of 0.10 microgram, including the highest mass of 0.27 microgram near the wetland. Toluene was detected in only five passive samplers, including masses of 0.65 microgram near the wetland and 0.85 microgram on the southwestern side of the landfill. The only other gasoline-related compound detected was octane in two samplers. Naphthalene was detected in two samplers in the gully near the landfill and two samplers along the southwestern side of the landfill, but had masses less than or equal to 0.02 microgram. Six samplers located southeast of the landfill had detections of chlorinated compounds, including one perchloroethene detections (0.04 microgram) and five chloroform detections (0.05 to0.08 microgram). Passive samplers were deployed and recovered on August 8, 2011, in nine monitoring wells along the southwestern, southeastern and northeastern sides of the landfill and down gradient from the eastern corner of the landfill. Six of the nine samplers had TPH concentrations greater than 100 micrograms per liter. TPH concentrations declined from 320 micrograms per liter in a sampler near the landfill to 18 micrograms in a sampler near the wetland. Five of the samplers had detections of one or more diesel compounds but detections of individual diesel compounds had concentrations below a method detection level of 0.01 microgram per liter. Benzene was detected in three samplers and exceeded the national primary drinking-water standard of 5 micrograms per liter set by the U.S. Environmental Protection Agency. The concentrations of benzene, and therefore BTEX, were 6.1 micrograms per liter in the sampler near the eastern corner of the landfill, 27 micrograms per liter in the sampler near the wetland, and 37 micrograms per liter in the sampler at the southern corner of the landfill. Nonfuel-related compounds were detected in the four wells that are aligned between the eastern corner of the landfill and the wetland. The sampler deployed nearest the eastern corner of the landfill had the greatest number of detected organic compounds and had the only detections of two trimethylbenzene compounds, naphthalene, 2-methyl naphthalene, and 1,4-dichlorobenzene. The two up gradient samplers had the greatest number of chlorinated compounds with five compounds each, compared to detections of four compounds and one compound in the two down gradient samplers. All four samplers had detections of 1,1-dichloroethane which ranged from 42 to 1,300 micrograms per liter. Other detections of chlorinated compounds included trichloroethene, perchloroethene, cis-1,2-dichloroethene, 1,1,1-trichloroethane and chloroform.

Falls, W. Fred; Caldwell, Andral W.; Guimaraes, Wladmir G.; Ratliff, W. Hagan; Wellborn, John B.; Landmeyer, James E.

2012-01-01

222

Passive soil venting at the Chemical Waste Landfill Site at Sandia National Laboratories, Albuquerque, New Mexico  

SciTech Connect

Passive Soil Vapor Extraction was tested at the Chemical Waste Landfill (CWL) site at Sandia National Laboratories, New Mexico (SNLIW). Data collected included ambient pressures, differential pressures between soil gas and ambient air, gas flow rates into and out of the soil and concentrations of volatile organic compounds (VOCS) in vented soil gas. From the differential pressure and flow rate data, estimates of permeability were arrived at and compared with estimates from other studies. Flow, differential pressure, and ambient pressure data were collected for nearly 30 days. VOC data were collected for two six-hour periods during this time. Total VOC emissions were calculated and found to be under the limit set by the Resource Conservation and Recovery Act (RCRA). Although a complete process evaluation is not possible with the data gathered, some of the necessary information for designing a passive venting process was determined and the important parameters for designing the process were indicated. More study is required to evaluate long-term VOC removal using passive venting and to establish total remediation costs when passive venting is used as a polishing process following active soil vapor extraction.

Phelan, J.M.; Reavis, B.; Cheng, W.C.

1995-05-01

223

Impacts of Deforestation and Land Cover Change on Mountain Soils in Hrazdan, Armenia  

Microsoft Academic Search

The impacts of deforestation and land cover change upon underlying soils were examined on one hillside in central Armenia. Soil characteristics in three land cover areas—forest, coppice, and pasture—were recorded and soil samples were analyzed. Deforestation and land cover change were found to increase erosion rates. From soil horizon and structural characteristics, it can be estimated that 40 cm of

Jason L. Rhoades; Michael Scott Demyan; Blair Orr

2011-01-01

224

Analysis of landfills with historic airphotos  

NASA Technical Reports Server (NTRS)

An investigation is conducted regarding the value of existing aerial photographs for waste management, including landfill monitoring. The value of historic aerial photographs for documenting landfill boundaries is shown in a graph in which the expansion of an active landfill is traced over a 40-year period. Historic aerial photographs can also be analyzed to obtain general or detailed land-use and land-cover information. In addition, the photographs provide information regarding other elements of the physical environment, including geology, soils, and surface and subsurface drainage. The value of historic photos is discussed, taking into account applications for inventory, assessing contamination/health hazards, planning corrective measures, planning waste collection and facilities, developing inactive landfills, and research concerning improved land-filling operations.

Erb, T. L.; Philipson, W. R.; Teng, W. L.; Liang, T.

1981-01-01

225

Assessment of soil-gas contamination at the 17th Street landfill, Fort Gordon, Georgia, 2011  

USGS Publications Warehouse

Assessments of contaminants in soil gas were conducted in two study areas at Fort Gordon, Georgia, in July and August of 2011 to supplement environmental contaminant data for previous studies at the 17th Street landfill. The two study areas include northern and eastern parts of the 17th Street landfill and the adjacent wooded areas to the north and east of the landfill. These study areas were chosen because of their close proximity to the surface water in Wilkerson Lake and McCoys Creek. A total of 48 soil-gas samplers were deployed for the July 28 to August 3, 2011, assessment in the eastern study area. The assessment mostly identified detections of total petroleum hydrocarbons (TPH), and gasoline- and diesel-range compounds, but also identified the presence of chlorinated solvents in six samplers, chloroform in three samplers, 2-methyl naphthalene in one sampler, and trimethylbenzene in one sampler. The TPH masses exceeded 0.02 microgram (?g) in all 48 samplers and exceeded 0.9 ?g in 24 samplers. Undecane, one of the three diesel-range compounds used to calculate the combined mass for diesel-range compounds, was detected in 17 samplers and is the second most commonly detected compound in the eastern study area, exceeded only by the number of TPH detections. Six samplers had detections of toluene, but other gasoline compounds were detected with toluene in three of the samplers, including detections of ethylbenzene, meta- and para-xylene, and octane. All detections of chlorinated organic compounds had soil-gas masses equal to or less than 0.08 ?g, including three detections of trichloroethene, three detections of perchloroethene, three chloroform detections, one 1,4-dichlorobenzene detection, and one 1,1,2-trichloroethane detection. Three methylated compounds were detected in the eastern study area, but were detected at or below method detection levels. A total of 32 soil-gas samplers were deployed for the August 11–24, 2011, assessment in the northern study area. All samplers in the survey had detections of TPH, but only eight of the samplers had detections of TPH greater than 0.9 mg. Four samplers had TPH detections greater than 9 mg; the only other fuel-related compounds detected in these four samplers included toluene in three of the samplers and undecane in the fourth sampler. Three samplers deployed along the western margin of the northern landfill had detections of both diesel-and gasoline-related compounds; however, the diesel-related compounds were detected at or below method detection levels. Seven samplers in the northern study area had detections of chlorinated compounds, including three perchloroethene detections, three chloroform detections, and one 1,4-dichloro-benzene detection. One sampler on the western margin of the landfill had detections of 1,2,4-trimethylbenzene and 1,3,5-tr-methylbenene below method detection levels.

Falls, W. Fred; Caldwell, Andral W.; Guimaraes, Wladmir G.; Ratliff, W. Hagan; Wellborn, John B.; Landmeyer, James E.

2012-01-01

226

Mobilization of soil and fertilizer phosphate by cover crops  

Microsoft Academic Search

Incorporation of cover crops into cropping systems may contribute to a more efficient utilization of soil and fertilizer P\\u000a by less P-efficient crops through exudation of P-mobilizing compounds by the roots of P-efficient plant species. The main\\u000a objective of the present work was to test this hypothesis. First a method has been developed which allows the quantification\\u000a of organic anion

Mahmoud Kamh; Walter J. Horst; Fathi Amer; Hamida Mostafa; Peter Maier

1999-01-01

227

PhysicoChemical properties, heavy metals and their relations in cultivated landfill soils dumped with municipal solid wastes  

Microsoft Academic Search

Long-term fate and behaviour of heavy metals in soil, treated with composted-municipal solid wastes (MSW), are largely unknown. Accordingly, we investigated some physico-chemical properties, the relative availability (RA) of heavy metals and Cd\\/Zn ratio in soils of a century old cultivated landfill site dumped with Calcutta-MSW during monsoon, winter and summer seasons of 1999-2001. This was done to assess the

A Mitra; P Bhattacharyya; K Chakrabarti; DJ Chattopadhyay; A Chakraborty

2003-01-01

228

Soil carbon sequestration via cover crops- A meta-analysis  

NASA Astrophysics Data System (ADS)

Agricultural soils are depleted in soil organic carbon (SOC) and have thus a huge potential to sequester SOC. This can primarily be achieved by increasing carbon inputs into the soil. Replacing winter fallows by cover crop cultivation for green manure has many benefits for the soil and forms an additional carbon input. An increase in carbon concentration has been reported in several studies worldwide. However, the effect on SOC stocks, as well as the influence of environmental parameters and management on SOC dynamics is not known. We therefore conducted a meta-analysis to investigate those issues. A total of 33 studies, comprising 47 sites and 147 plots were compiled. A pedotransfer function was used to estimate bulk densities and calculate SOC stocks. SOC stock change was found to be a linear function of time since introduction, with an annual sequestration rate of 0.32 Mg C ha-1 yr-1. Since no saturation was visible in the observations, we used the model RothC to estimate a new steady state level and the resulting total SOC stock change for an artificial "average cropland". The total average SOC stock change with an annual input of 1.87 Mg C ha-1 yr-1 was 16.76 Mg C ha-1 for the average soil depth of 22 cm. We estimated a potential global SOC sequestration of 0.12±0.03 Pg C yr-1, which would compensate for 8 % of the direct annual greenhouse gas emissions from agriculture.

Poeplau, Christopher; Don, Axel

2014-05-01

229

Monitoring the Performance of an Alternative Landfill Cover at the Monticello, Utah, Uranium Mill Tailings Disposal Site  

Microsoft Academic Search

The U.S. Department of Energy Office of Legacy Management (DOE) and the U.S. Environmental Protection Agency (EPA) collaborated on the design and monitoring of an alternative cover for the Monticello uranium mill tailings disposal cell, a Superfund site in southeastern Utah. Ground-water recharge is naturally limited at sites like Monticello where thick, fine-textured soils store precipitation until evaporation and plant

W. J. Waugh; M. K. Kastens; L. R. L. Sheader; C. H. Benson; W. H. Albright; P. S. Mushovic

2008-01-01

230

Methane emissions from MBT landfills.  

PubMed

Within the scope of an investigation for the German Federal Environment Agency ("Umweltbundesamt"), the basics for the estimation of the methane emissions from the landfilling of mechanically and biologically treated waste (MBT) were developed. For this purpose, topical research including monitoring results regarding the gas balance at MBT landfills was evaluated. For waste treated to the required German standards, a methane formation potential of approximately 18-24 m(3)CH(4)/t of total dry solids may be expected. Monitoring results from MBT landfills show that a three-phase model with differentiated half-lives describes the degradation kinetics in the best way. This is due to the fact that during the first years of disposal, the anaerobic degradation processes still proceed relatively intensively. In addition in the long term (decades), a residual gas production at a low level is still to be expected. Most of the soils used in recultivation layer systems at German landfills show a relatively high methane oxidation capacity up to 5 l CH(4)/(m(2)h). However, measurements at MBT disposal sites indicate that the majority of the landfill gas (in particular at non-covered areas), leaves the landfill body via preferred gas emission zones (hot spots) without significant methane oxidation. Therefore, rather low methane oxidation factors are recommended for open and temporarily covered MBT landfills. Higher methane oxidation rates can be achieved when the soil/recultivation layer is adequately designed and operated. Based on the elaborated default values, the First Order Decay (FOD) model of the IPCC Guidelines for National Greenhouse Gas Inventories, 2006, was used to estimate the methane emissions from MBT landfills. Due to the calculation made by the authors emissions in the range of 60,000-135,000 t CO(2-eq.)/a for all German MBT landfills can be expected. This wide range shows the uncertainties when the here used procedure and the limited available data are applied. It is therefore necessary to generate more data in the future in order to calculate more precise methane emission rates from MBT landfills. This is important for the overall calculation of the climate gas production in Germany which is required once a year by the German Government. PMID:23756351

Heyer, K-U; Hupe, K; Stegmann, R

2013-09-01

231

Winter cover cropping influence on nitrogen mineralization, presidedress soil nitrate test, and corn yields  

Microsoft Academic Search

The mineralization and availability of cover crop N to the succeeding crop are critical components in the management of soil N to reduce N leaching. The effects of several leguminous and non-leguminous cover crops on soil N availability, N mineralization potential, and corn (Zea mays L.) yield were examined. The cover crops had variable effects on soil N availability and

S. Kuo; U. M. Sainju; E. Jellum

1996-01-01

232

Land Cover Differences in Soil Carbon and Nitrogen at Fort Benning, Georgia  

Microsoft Academic Search

Land cover characterization might help land managers assess the impacts of management practices and land cover change on attributes linked to the maintenance and\\/or recovery of soil quality. However, connections between land cover and measures of soil quality are not well established. The objective of this limited investigation was to examine differences in soil carbon and nitrogen among various land

Garten Jr

2004-01-01

233

Cover crops enhance soil organic matter, carbon dynamics and microbiological function in a vineyard agroecosystem  

Microsoft Academic Search

Impacts of soil tillage and cover crops on soil carbon (C) dynamics and microbiological function were investigated in a vineyard grown in California's mediterranean climate. We (1) compared soil organic matter (SOM), C dynamics and microbiological activity of two cover crops [Trios 102 (Triticale×Triosecale) (‘Trios’), Merced Rye (Secale cereale) (‘Rye’)] with cultivation (‘Cultivation’) and (2) evaluated seasonal effects of soil

Kerri Steenwerth; K. M. Belina

2008-01-01

234

Engineering Review of the Use of Leached Brown Coal Ash in Soil Covers  

Microsoft Academic Search

The need to engineer cover systems for the successful rehabilitation or remediation of a wide variety of solid wastes is increasing. Some common applications include landfills, hazardous waste repositories, or mine tailings dams and waste rock\\/overburden dumps. The brown coal industry of the Latrobe Valley region of Victoria, Australia, produces significant quantities of coal ash and overburden annually. There are

Gavin M Mudd; Srijib Chakrabarti; Jayantha Kodikara

235

Fate and distribution of nitrogen in soil and plants irrigated with landfill leachate.  

PubMed

Landfill leachate contains a high concentration of ammoniacal substances which can be a potential supply of N for plants. A bioassay was conducted using seeds of Brassica chinensis and Lolium perenne to evaluate the phytotoxicity of the leachate sample. A soil column experiment was then carried out in a greenhouse to study the effect of leachate on plant growth. Two grasses (Paspalum notatum and Vetiver zizanioides) and two trees (Hibiscus tiliaceus and Litsea glutinosa) were irrigated with leachate at the EC50 levels for 12 weeks. Their growth performance and the distribution of N were examined and compared with columns applied with chemical fertilizer. With the exception of P. notatum, plants receiving leachate and fertilizer grew better than those receiving water alone. The growth of L. glutinosa and V. zizanioides with leachate irrigation did not differ significantly from plants treated with fertilizer. Leachate irrigation significantly increased the levels of NH(x)-N in soil. Although NO(x)-N was below 1 mg NL(-1) in the leachate sample, the soil NO(x)-N content increased by 9-fold after leachate irrigation, possibly as a result of nitrification. Leachate irrigation at EC50 provided an N input of 1920 kg N ha(-1) over the experimental period, during which up to 1050 kg N ha(-1) was retained in the soil and biomass, depending on the type of vegetation. The amount of nutrient added seems to exceed beyond the assimilative capability. Practitioners should be aware of the possible consequence of N saturation when deciding the application rate if leachate irrigation is aimed for water reuse. PMID:21349695

Cheng, C Y; Chu, L M

2011-06-01

236

The soil–air exchange characteristics of total gaseous mercury from a large-scale municipal landfill area  

Microsoft Academic Search

The cycle of mercury (Hg) from a gigantic landfill area (area ?2.72km2) was investigated by conducting micrometeorological measurements of its exchange rates across soil–air boundary during the spring season of 2000. Based on this field campaign, we attempted to provide various insights into the Hg exchange processes, especially with respect to the decoupling of the mixed signatures of complex source

Ki-Hyun Kim; Min-Young Kim; Gangwoong Lee

2001-01-01

237

Soils and the soil cover of the taiga zone in the northern Urals (upper reaches of the Pechora River)  

NASA Astrophysics Data System (ADS)

The territory in the upper reaches of the Pechora River is characterized by the predominance of Al-Fe-humus and metamorphic soils with gley features developing under the middle taiga fir-spruce forests rather than gley-podzolic soils as had been considered before. Some of the described soil profiles represent intergrades between brown taiga soils (burozems) and gleysols; these soils are absent in the new Russian soil classification system. General regularities of the soil cover are controlled by the geomorphic position of the soils on slopes and by the conditions of ground moistening and lateral soil water flows. The development of modern soil cover patterns is determined by the impact of herbaceous and woody vegetation, bioturbation of the soils by windfalls, the presence of dead tree trunks on the soil surface, and other factors.

Semikolennykh, A. A.; Bovkunov, A. D.; Aleinikov, A. A.

2013-08-01

238

Geoelectrical investigation of old/abandoned, covered landfill sites in urban areas: model development with a genetic diagnosis approach  

NASA Astrophysics Data System (ADS)

Geoelectrical methods have an important, albeit difficult role to play in landfill investigations. In the present economic conditions, with the environmentally sensitive regime, adequate desk-study and model development are essential ingredients for a successful site investigation of landfills. This paper attempts to develop a genetic investigative model for old/abandoned landfill sites where the records of operations are not available. The main elements of the model are the site boundaries, age and nature of anthropogenic deposits, depth and dip of the layers of refuse and sealing materials, the integrity and shape of the capping zones or separating walls and basal floor slopes, the position of concealed access roads in the site, the water table (or perched water bodies within the refuse) and the presence of leachate. The attendant geotechnical, hydrogeological, and bio-geochemical constraints at such sites are also incorporated in the model for consistency of practical solutions to landfill problems. The nature of anthropogenic deposits and the spatial-temporal characteristics of leachates are reviewed in a geoelectrical context. The analogy between waste degradation and leaching, and the well-known weathering processes of supergene mineral enrichment and saprolite formation in crystalline rocks is explored, and used to develop a conceptual resistivity-vs.-depth model for landfill sites. The main tenet of the model is that vertical conductivity profiles will attain maximum values in the zone of mineral enrichment near the water table and tail-off away from it. This conceptual resistivity model is shown to be consistent with non-invasive observations in landfill sites in different geographical environments. Power-law relationships are found to exist between some geoelectrically important hydrochemical parameters (fluid conductivity, chloride content and total dissolved solids) in leachates and leachate-contaminated groundwater from some landfill sites. Since some chemical parameters of fill are known to vary consistently with time, a plausible hydrochemical and age-deductive scheme for saturated fill is proposed for geoelectrical models of landfills without significant amounts of metal. Practical suggestions are made for a consistent approach in geoelectrical investigation and diagnosis of old landfill sites. A few field examples are used to illustrate the diagnosis approach.

Meju, Maxwell A.

2000-05-01

239

Microbial Biomass and Activities in Soil Aggregates Affected by Winter Cover Crops  

Microsoft Academic Search

vegetable cropping systems (Burket et al., 1997); how- ever, it is unclear whether legumes or nonlegumes are Winter cover crops may increase soil organic matter (SOM) and the most suitable for this task. Leguminous winter cover improve soil structure in intensively managed summer vegetable crop- ping systems. Our study examined the influence of three cover crop crops have the potential

I. C. Mendes; A. K. Bandick; R. P. Dick; P. J. Bottomley

1999-01-01

240

The effects of cover crops on soil physical properties and nutrient cycling  

Microsoft Academic Search

Cover crops improve soil aggregate stability, increase water infiltration, and legume cover crops also fix nitrogen and scavenge nutrients that are subject to leaching. Greenhouse and field experiments were conducted in Indiana to measure growth of different cover crops and their effects on soil properties. The objective of the greenhouse experiment was to study the response of three varieties of

Mohammad Zaman Amini

2011-01-01

241

Role of Cover Crops in Improving Soil and Row Crop Productivity  

Microsoft Academic Search

Cover crops play an important role in improving productivity of subsequent row crops by improving soil physical, chemical, and biological properties. The objective of this article is to review recent advances in cover crops practice, in the context of potential benefits and drawbacks for annual crop production and sustained soil quality. Desirable attributes of a cover crop are the ability

N. K. Fageria; V. C. Baligar; B. A. Bailey

2005-01-01

242

Magnetic, geo-electric, and groundwater and soil quality analysis over a landfill from a lead smelter, Cairo, Egypt  

NASA Astrophysics Data System (ADS)

A detailed ground magnetic survey, geoelectric vertical electric sounding (VES), and groundwater and soil quality analysis were conducted in the area of the abandoned landfill of the Awadallah lead (Pb) smelter, northeastern Cairo, Egypt. The integration between the applied techniques located successfully the buried solid waste, demarcated the groundwater and its possible contamination, and determined the lead level in soil. Magnetic survey comprised 50 magnetic profiles each 190 m length. Vertical derivatives, wavelength filters, and continuation filters characterized the eastern and central parts of the landfill by high intense magnetic anomalies reflecting metal and lead wastes, whereas the western part was characterized by low intense anomalies indicating change in the landfill composition to non-magnetized material. The geoelectric survey comprised 16 VES with a maximum AB/2 of 100 m. The inverted data demarcated effectively the groundwater aquifer with depth ranged from 11 to 18 m and true resistivities ranged from 96 to 118 ?·m. The second layer (Holocene-Q3) of semi-permeable silty and sandy clay cap (true resistivities 29 ~ 51 ?·m and thickness 9-17 m) constituted a considerable role in limiting the possible contamination from the landfill. The analyzed groundwater parameters pH, Eh, TDS, SEC, and DO indicated a good water quality with homogenous aquifer characteristics, whereas the lead concentration in groundwater (0.033-0.036 mg/L) was slightly exceeding the safe limits identified by the U.S. EPA (? 0.015 mg/L). Lead in soil samples revealed elevated concentrations (3130 mg/L/kg at VES-3) around the Awadallah smelter, whereas a gradual decrease in concentrations was recorded in the northwestern direction.

Khalil, Mohamed H.

2012-11-01

243

Quantifying methane oxidation from landfills using stable isotope analysis of downwind plumes  

Microsoft Academic Search

Landfills are major contributors to the atmospheric CHâ budget. A major uncertainty in estimating CHâ emission by methanotrophic bacteria in the aerobic outer portions of the cover soil. These bacteria intercept the gas as it migrates toward the atmosphere. To estimate cover soil oxidation, the authors made seasonal measurements of the difference in the δ¹³C of CHâ within the anoxic

J. P. Chanton; C. M. Rutkowski; B. Mosher

1999-01-01

244

Minimum depth of soil cover above long-span soil-steel railway bridges  

NASA Astrophysics Data System (ADS)

Recently, soil-steel bridges have become more commonly used as railway-highway crossings because of their economical advantages and short construction period compared with traditional bridges. The currently developed formula for determining the minimum depth of covers by existing codes is typically based on vehicle loads and non-stiffened panels and takes into consideration the geometrical shape of the metal structure to avoid the failure of soil cover above a soil-steel bridge. The effects of spans larger than 8 m or more stiffened panels due to railway loads that maintain a safe railway track have not been accounted for in the minimum cover formulas and are the subject of this paper. For this study, two-dimensional finite element (FE) analyses of four low-profile arches and four box culverts with spans larger than 8 m were performed to develop new patterns for the minimum depth of soil cover by considering the serviceability criterion of the railway track. Using the least-squares method, new formulas were then developed for low-profile arches and box culverts and were compared with Canadian Highway Bridge Design Code formulas. Finally, a series of three-dimensional (3D) finite element FE analyses were carried out to control the out-of-plane buckling in the steel plates due to the 3D pattern of train loads. The results show that the out-of-plane bending does not control the buckling behavior of the steel plates, so the proposed equations for minimum depth of cover can be appropriately used for practical purposes.

Esmaeili, Morteza; Zakeri, Jabbar Ali; Abdulrazagh, Parisa Haji

2013-12-01

245

A statistical model for landfill surface emissions.  

PubMed

Landfill operators require a rapid, simple, low-cost, and accurate method for estimation of landfill methane surface emissions over time. Several methods have been developed to obtain instantaneous field measurements of landfill methane surface emissions. This paper provides a methodology for interpolating instantaneous measurements over time, taking variations in meteorological conditions into account. The goal of this study was to determine the effects of three factors on landfill methane surface emissions: air temperature, pressure gradient between waste and atmosphere, and soil moisture content of the cover material. On the basis of a statistical three-factor and two-level full factorial design, field measurements of methane emissions were conducted at the City of Montreal landfill site during the summer of 2004. Three areas were measured: test area 1 (4800 m2), test area 2 (1400 m2), and test area 3 (1000 m2). Analyses of variance were performed on the data. They showed a significant statistical effect of the three factors and the interaction between temperature and soil moisture content on methane emissions. Analysis also led to the development of a multifactor correlation, which can be explained by the underlying processes of diffusive and advective flow and biological oxidation. This correlation was used to estimate total emissions of the three test areas for July and August 2004. The approach was validated using a second dataset for another area adjacent to the landfill. PMID:20222535

Héroux, Martin; Guy, Christophe; Millette, Denis

2010-02-01

246

Assessment of soil-gas, soil, and water contamination at the former 19th Street landfill, Fort Gordon, Georgia, 2009-2010  

USGS Publications Warehouse

Soil gas, soil, and water were assessed for organic and inorganic constituents at the former 19th Street landfill at Fort Gordon, Georgia, from February to September 2010. Passive soil-gas samplers were analyzed to evaluate organic constituents in the hyporheic zone and flood plain of a creek and soil gas within the estimated boundaries of the former landfill. Soil and water samples were analyzed to evaluate inorganic constituents in soil samples, and organic and inorganic constituents in the surface water of a creek adjacent to the landfill, respectively. This assessment was conducted to provide environmental constituent data to Fort Gordon pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. The passive soil-gas samplers deployed in the water-saturated hyporheic zone and flood plain of the creek adjacent to the former landfill indicated the presence of total petroleum hydrocarbon (TPH) and octane above method detection levels in groundwater beneath the creek bed and flood plain at all 12 soil-gas sampler locations. The TPH concentrations ranged from 51.4 to 81.4 micrograms per liter. Octane concentrations ranged from 1.78 to 2.63 micrograms per liter. These detections do not clearly identify specific source areas in the former landfill; moreover, detections of TPH and octane in a soil-gas sampler installed at a seep on the western bank of the creek indicated the potential for these constituents to be derived from source areas outside the estimated boundaries of the former landfill. A passive soil-gas sampler survey was conducted in the former landfill from June 30 to July 5, 2010, and involved 56 soil-gas samplers that were analyzed for petroleum and halogenated compounds not classified as chemical agents or explosives. The TPH soil-gas mass exceeded 2.0 micrograms in 21 samplers. Most noticeable are the two sites with TPH detections which are located in and near the hyporheic zone and are likely to affect the creek. However, most TPH detections were located in and immediately adjacent to a debris field located within the former landfill and in areas where debris was not visible, including the northwestern and southeastern parts of the study area. Two of the four soil-gas samplers installed within a former military training area adjacent to the landfill also had TPH detections above the method detection level. Benzene, toluene, ethylbenzene, and xylene (as combined BTEX mass) were detected at 0.02 microgram or greater in three soil-gas samplers installed at the northwestern boundary and in five samplers installed in the southeastern part of the study area. There was no BTEX mass detected above the method detection level in samplers installed in the debris field. Toluene was the most frequently detected BTEX compound. Compounds indicative of diesel-range organics were detected above 0.04 microgram in 12 soil-gas samplers and had a distribution similar to that of TPH, including being detected in the debris field. Undecane was the most frequently detected diesel compound. Chloroform and naphthalene were detected in eight and two soil-gas samplers, respectively. Five soil-gas samplers deployed during September 2010 were analyzed for organic compounds classified as chemical agents and explosives, but none exceeded the method detection levels. Five composite soil samples collected from within the estimated boundaries of the former landfill were analyzed for 35 inorganic constituents, but none of the constituents detected exceeded regional screening levels for industrial soils. The sample collected in the debris field exceeded background levels for aluminum, barium, calcium, chromium, lead, nickel, potassium, sodium, and zinc. Three surface-water samples were collected in September 2010 from a stormwater outfall culvert that drains to the creek and from the open channel of the creek at upstream and downstream locations relative to the outfall. Toluene was detected at 0.661 mi

Falls, W. Fred; Caldwell, Andral W.; Guimaraes, Wladmir B.; Ratliff, W. Hagan; Wellborn, John B.; Landmeyer, James E.

2011-01-01

247

Accelerated methane oxidation cover system to reduce greenhouse gas emissions from MSW landfills in cold, semi-arid regions  

Microsoft Academic Search

Many regional landfills for municipal solid waste (MSW) and industrial, commercial, institutional (ICI) wastes in cold, dry regions do not produce enough gas to support conventional gas extraction, treatment, and utilization or flaring. Yet, some solution is required to reduce emissions of methane and trace constituents to the atmosphere for the protection of the public and of the global climate.

Chris A Zeiss

2006-01-01

248

Short-term effects of cover crop incorporation on soil carbon pools and nitrogen availability  

Microsoft Academic Search

Winter cover crops are increasingly used to maintain water quality and\\u000a agoecosystem productivity. Cover crop incorporation influences transient\\u000a soil microbial dynamics and nutrient availability at an early growth\\u000a stage of subsequent crops. Short-term (less than or equal to 35 d)\\u000a effects of cover crop incorporation on soil C pools and N availability\\u000a were evaluated using sandy loam soils from organically

S Hu; NJ Grunwald; AHC vanBruggen; GR Gamble; LE Drinkwater; C Shennan; MW Demment

1997-01-01

249

Summer cover crops and soil amendments to improve growth and nutrient uptake of okra  

SciTech Connect

A pot experiment with summer cover crops and soil amendments was conducted in two consecutive years to elucidate the effects of these cover crops and soil amendments on 'Clemson Spineless 80' okra (Abelmoschus esculentus) yields and biomass production, and the uptake and distribution of soil nutrients and trace elements. The cover crops were sunn hemp (Crotalaria juncea), cowpea (Vigna unguiculata), velvetbean (Mucuna deeringiana), and sorghum sudan-grass (Sorghum bicolor x S. bicolor var. sudanense) with fallow as the control. The organic soil amendments were biosolids (sediment from wastewater plants), N-Viro Soil (a mixture of biosolids and coal ash), coal ash (a combustion by-product from power plants), co-compost (a mixture of 3 biosolids: 7 yard waste), and yard waste compost (mainly from leaves and branches of trees and shrubs, and grass clippings) with a soil-incorporated cover crop as the control. As a subsequent vegetable crop, okra was grown after the cover crops, alone or together with the organic soil amendments, had been incorporated. All of the cover crops, except sorghum sudangrass in 2002-03, significantly improved okra fruit yields and the total biomass production. Both cover crops and soil amendments can substantially improve nutrient uptake and distribution. The results suggest that cover crops and appropriate amounts of soil amendments can be used to improve soil fertility and okra yield without adverse environmental effects or risk of contamination of the fruit. Further field studies will be required to confirm these findings.

Wang, Q.R.; Li, Y.C.; Klassen, W. [University of Florida, Homestead, FL (United States). Center for Tropical Research & Education

2006-04-15

250

Assessment of the impacts of dynamic soil properties and vegetation cover on soil erosion using distributed hydrological model  

NASA Astrophysics Data System (ADS)

The challenges in soil erosion modeling are mainly attributed to the heterogeneity of the soil properties and the complex interactions between vegetation cover and soil erosion processes. Current process-based soil erosion models apply empirical adjustment factors to account for the influences of vegetation cover and land managements. Most of soil erosion models assume that the temporal changes of soil properties are negligible over temporal scale ranging from several days to decades. Physically meaningful model representations of soil erosion processes require deep understanding of the mechanisms through which vegetation cover influences the soil particles detachment and transport, as well as the temporal-spatial changes of soil properties. In this study, the dynamic changes of soil properties in soil erosion modeling were investigated, through a distributed soil erosion model (GEOTOP-erosion). Specifically, spatially distributed and dynamical soil variables are introduced into the soil erosion model. Soil particles associated with different grain sizes experience different transport processes. Soil textures and organic matter (OM) contents are updated daily according to the feedbacks on erosion and deposition processes. Other related soil properties are derived by the updated soil textures and OM contents. The influences of vegetation cover are represented by four major mechanisms: (1) modifying net rainfall and raindrop energy by canopy interception, (2) reducing runoff generation by transpiration, (3) retarding overland flow by increasing surface roughness, and (4) increasing soil cohesion by root system. The simulations of this soil erosion model show appropriate interactions between vegetation cover and soil erosion processes. The erosion process could also be dynamically adjusted by the evolution of soil properties. An experimental catchment in Ireland was selected to test the soil erosion model. The simulation results show a good agreement between estimated and observed soil loss in complex land surface conditions. The simulations incorporated dynamic soil properties demonstrate more accurate soil erosion simulation. The coupled model could be extended to more broad applications, such as evaluation of anthropogenic activities, estimation of influences of soil disturbances and long term soil evolution.

Zi, T.; Kiely, G.; Albertson, J. D.

2012-12-01

251

The effects of different soil cover management practices on plant biodiversity and soil properties in Mediterranean ancient olive orchards  

NASA Astrophysics Data System (ADS)

The effects of different soil cover management practices on plant biodiversity and soil properties in Mediterranean ancient olive orchards Madzaric S., Aly A., Ladisa G. and Calabrese G. The loss of natural plant cover due to the inappropriate soil cover management is often a decisive factor for soil degradation in Mediterranean area. This accompanied with typical climate, characterized by cool, wet winters and hot and dry summers leads to soil erosion and loss of productivity. Due to simplification of agricultural practice and to the attempt to decrease cost of production, keeping soil bare is a widespread agricultural practice in Mediterranean ancient olive orchards (AOOs). The consequences of this are degradation of soil quality and reduction of plant biodiversity. In last year's some alternative practices are proposed in order to protect soil and biodiversity. One of these practices is the "grassing" i.e. covering the soil by selected autochthonous plant species. Objectives of our study are: (1) to evaluate impact of different soil cover management practices on soil properties and plant biodiversity in AOOs and (2) to define a minimum indicators' set (Minimum Data Set - MDS) to evaluate the effectiveness of different agricultural practices in environmental performance of AOOs. A comparison was carried on considering two management systems (conventional vs. organic) and three agricultural practices: conventional with bare soil (CON), organic with soil covered by selected autochthonous species (MIX) and organic left to the native vegetation (NAT). In general a clear positive influence of organic management system was recognized. Some soil quality indicators (physical, chemical and biological) showed responsiveness in describing the effects of management system and agricultural practices on soil properties. The both approaches with vegetation cover on the soil surface (either sowing of mixture or soil left to the natural plant cover) performed better than conventional one with repeated tillage and bare soil during the whole year. This is peculiarly visible in the case of soil erosion that presents an enormous problem in Mediterranean region. No clear differences resulted between the two organic practices for soil management (natural cover and grassing). Key words: organic agriculture, ecological indicators, agricultural practices, soil quality, olive groves

Madzaric, Suzana; Aly, Adel; Ladisa, Gaetano; Calabrese, Generosa

2014-05-01

252

Terrain Control on Soil Organic Carbon Distribution in Loess Soils with Varying Land Cover  

NASA Astrophysics Data System (ADS)

The distribution and stability of soil organic carbon (SOC) pools at the landscape scale is dependent upon a number of factors including vegetation inputs and rates of soil loss or accumulation. In order to create a broader framework with which to characterize the size and stability of SOC pools across the landscape, we are combining deep profile measurements of SOC with terrain attributes (stream power index, compound topographic index, curvature) for a suite of sites from southeastern Minnesota. Terrain attributes are based on an advanced yet widely available digital elevation model (LIDAR-derived) and allow sample site selection targeted to represent the range of landscape elements without assuming a simple hillslope profile. By constraining for climate and parent material (loess), we are conducting these landscape-scale assessments of SOC across sites with land cover ranging from perennial grassland vegetation to row-crop agriculture. When coupled with measurements of 137Cs, 13C and 14C (ongoing), results from this study will allow us to ultimately relate decadal-scale soil redistribution to landscape attributes and inputs from vegetation cover. This coupling of terrain attributes and field measurements will help to identify which landscape elements (and management practices) are conducive to maintaining soil quality and terrestrial SOC pools. Our work aims to provide an example of how easily available terrain models can be used to predict SOC attributes across spatiotemporal scales.

Dalzell, B. J.; Fissore, C.; Nater, E. A.; Yoo, K.

2010-12-01

253

What's left? - Investigations on soil cover of conservation tillage methods in Austria  

NASA Astrophysics Data System (ADS)

One of the most accepted and a practicable method to prevent soil from erosion is conservation tillage. If conservation tillage practices are performed in a proper way soil is protected from wind and water erosion. This study deals with the effectivity of conservation tillage practices under real field conditions. Therefore we i) carried out rainfall simulation experiments employing conservation tillage practices which had been proposed by farmers to test whether actual conservation tillage practices would be effective, ii) did an observation of mean soil cover on arable land after seeding in Lower and Upper Austria for field sites where conservation tillage was funded. Rainfall simulation experiments were carried out in the years 2011 and 2012 for various conservation tillage treatments consisting of different mulching and no tillage techniques. To evaluate results on surface runoff and erosion we additionally measured soil cover, bulk densities and surface roughness of the experimental plots. Soil cover estimation of the arable land in Lower and Upper Austria which is funded for conservation tillage practices was done in 2012 and 2013. Altogether on 146 randomly chosen field sites soil cover was estimated by using an object-based image analysis method. Results reveal that the effectiveness of conservation tillage was depending on the existence of a sufficient soil cover. However, under conditions of actual farm practices, a sufficient soil cover was not obtained for mulching treatments in 2011 and only partially in 2012. Therefore, mulching treatments partially gained even higher surface runoff and soil loss rates than conventional tillage practices. Due to their high soil cover, soil loss and surface runoff of no tillage treatments were very small as compared to all other tested treatments. The results of the soil cover estimation in Lower and Upper Austria show that under practicable land use a mean soil cover of 12 percent can be reached, what's rather low in a sense of soil erosion prevention compared to the results of our rainfall simulation experiments and literature.

Bauer, Thomas; Hösl, Rosemarie; Strauss, Peter

2014-05-01

254

Cover crop effects on the fate of N following soil application of swine manure  

Microsoft Academic Search

Cereal grain cover crops increase surface cover, anchor corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] residues, increase infiltration, reduce both rill and interrill erosion, scavenge excess nutrients from the soil, and are easily obtained and inexpensive compared to other cover crop options. The use of cereal grain cover crops in fields where manure application occurs should increase

T. B. Parkin; T. C. Kaspar; J. W. Singer

2006-01-01

255

Agricultural land cover mapping with the aid of digital soil survey data  

NASA Technical Reports Server (NTRS)

A study is recounted which assessed the effect of stratifying multidate Landsat MSS data on land cover classification accuracy. The study area covered 49,184 ha (121,534 acres) in Gentry County in northwestern Missouri. A pixel-by-pixel comparison of the two land cover classifications with field-verified land cover indicated improvements in identification of all cover types when land areas were stratified by soils. The introduction of soil map information to the land cover mapping process can improve discrimination of land cover types and reduce confusion among crop types that may be caused by soil-specific management practices, soil-induced crop development differences, and background reflectance characteristics.

Stoner, E. R.

1982-01-01

256

Modeling soil depth from topographic and land cover attributes  

Microsoft Academic Search

Soil depth is an important input parameter in hydrological and ecological modeling. Presently, the soil depth data available in national soil databases (STATSGO and SSURGO) from the Natural Resources Conservation Service are provided as averages within generalized land units (map units). Spatial uncertainty within these units limits their applicability for distributed modeling in complex terrain. This work reports statistical models

Teklu K. Tesfa; David G. Tarboton; David G. Chandler; James P. McNamara

2009-01-01

257

Environment, safety, health, and quality plan for the TRU- Contaminated Arid Soils Project of the Landfill Stabilization Focus Area Program  

SciTech Connect

The Landfill Stabilization Focus Area (LSFA) is a program funded by the US Department of Energy Office of Technology Development. LSFA supports the applied research, development, demonstration, testing, and evaluation of a suite of advanced technologies that together form a comprehensive remediation system for the effective and efficient remediation of buried waste. The TRU-Contaminated Arid Soils project is being conducted under the auspices of the LSFA Program. This document describes the Environment, Safety, Health, and Quality requirements for conducting LSFA/Arid Soils activities at the Idaho National Engineering Laboratory. Topics discussed in this report, as they apply to LSFA/Arid Soils operations, include Federal, State of Idaho, and Environmental Protection Agency regulations, Health and Safety Plans, Quality Program, Data Quality Objectives, and training and job hazard analysis. Finally, a discussion is given on CERCLA criteria and system and performance audits as they apply to the LSFA Program.

Watson, L.R.

1995-06-01

258

Interannual Herbaceous Biomass Response to Increasing Honey Mesquite Cover on Two Soils  

Microsoft Academic Search

This study quantified herbaceous biomass responses to increases in honey mesquite (Prosopis glandulosa Torr.) cover on two soils from 1995 to 2001 in north central Texas. Vegetation was sampled randomly with levels of mesquite ranging from 0% to 100%. With no mesquite covering the silt loam soils of bottomland sites, peak herbaceous biomass averaged (6SE) 3 300 6 210 kg

W. Richard Teague; R. Jim Ansley; William E. Pinchak; Steven L. Dowhower; Shannon A. Gerrard; J. Alan Waggoner

2008-01-01

259

Cover crop effect on soil carbon fractions under conservation tillage cotton  

Microsoft Academic Search

Cover crops may influence soil carbon (C) sequestration and microbial biomass and activities by providing additional residue C to soil. We examined the influence of legume [crimson clover (Trifolium incarnatum L.)], nonlegume [rye (Secale cereale L.)], blend [a mixture of legumes containing balansa clover (Trifolium michelianum Savi), hairy vetch (Vicia villosa Roth), and crimson clover], and rye+blend mixture cover crops

Upendra M. Sainju; Harry H. Schomberg; Bharat P. Singh; Wayne F. Whitehead; P. Glynn Tillman; Sharon L. Lachnicht-Weyers

2007-01-01

260

FINDINGS OF INTERNATIONAL REVIEW OF SOIL COVER DESIGN AND CONSTRUCTION PRACTICES FOR MINE WASTE CLOSURE1  

Microsoft Academic Search

Selected results of an international review of soil cover design and construction practices and performance is presented in this paper. The review, which was carried out in 2003, initially included 177 case studies in 14 countries. This has subsequently been updated to include more than 200 individual case studies. The case studies include soil covers for tailings impoundments, waste rock

Maritz Rykaart; Daryl Hockley; Michel Noel; Michael Paul

261

Ruminant Grazing of Cover Crops: Effects on Soil Properties and Agricultural Production  

ERIC Educational Resources Information Center

Integrating livestock into a cropping system by allowing ruminant animals to graze cover crops may yield economic and environmental benefits. The effects of grazing on soil physical properties, soil organic matter, nitrogen cycling and agricultural production are presented in this literature review. The review found that grazing cover crops…

Poffenbarger, Hanna

2010-01-01

262

Examining Changes in Soil Organic Carbon with Oat and Rye Cover Crops Using Terrain Covariates  

Microsoft Academic Search

Winter cover crops have the potential to increase soil organic C in the corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation in the upper Midwest. Management effects on soil C, however, are often difficult to measure because of the spatial variation of soil C across the landscape. The objective of this study was to determine the effect of oat

T. C. Kaspar; T. B. Parkin; D. B. Jaynes; C. A. Cambardella; D. W. Meek; Y. S. Jung

2006-01-01

263

Effects of soil composition and mineralogy on remote sensing of crop residue cover  

Microsoft Academic Search

The management of crop residues (non-photosynthetic vegetation) in agricultural fields influences soil erosion and soil carbon sequestration. Remote sensing methods can efficiently assess crop residue cover and related tillage intensity over many fields in a region. Although the reflectance spectra of soils and crop residues are often similar in the visible, near infrared, and the lower part of the shortwave

Guy Serbin; Craig S. T. Daughtry; E. Raymond Hunt; James B. Reeves; David J. Brown

2009-01-01

264

Differentiation of the soil cover in the lower Ob River valley  

Microsoft Academic Search

Specific features of the soil cover in the lower reaches of the Ob River are analyzed. The physicochemical properties and composition of the floodplain soils in different parts of the valley and on different floodplain elements are given. A comparative geographical analysis of the accumulation of macro-and microelements in the floodplain soils as a result of alluviation processes in the

E. G. Nechaeva

2008-01-01

265

Multi-scale variability in tropical soil nutrients following land-cover change  

Microsoft Academic Search

The effects of land-cover change on soil properties have reached regional proportions in the southwestern Amazon, and can be detected in their patterns at the scale of hundreds of thousands of square kilometers. Spatial analysis of an extensive soil profile database revealed four nested spatial scales at which different patterns in soil properties occur: 68 km. The shortest scales account for

Karen W. Holmes; Phaedon C. Kyriakidis; Oliver A. Chadwick; João Vianei Soares; Dar A. Roberts

2005-01-01

266

The short-term cover crops increase soil labile organic carbon in southeastern Australia  

Microsoft Academic Search

Little information is available about the effects of cover crops on soil labile organic carbon (C), especially in Australia.\\u000a In this study, two cover crop species, i.e., wheat and Saia oat, were broadcast-seeded in May 2009 and then crop biomass was\\u000a crimp-rolled onto the soil surface at anthesis in October 2009 in southeastern Australia. Soil and crop residue samples were

Xiaoqi Zhou; Chengrong Chen; Shunbao Lu; Yichao Rui; Hanwen Wu; Zhihong Xu

267

COTORAN WASH-OFF FROM COVER CROP RESIDUES AND DEGRADATION IN GIGGER SOIL  

Microsoft Academic Search

Cover crop residues on no-till soil will intercept a portion of applied herbicides. Thus, herbicide efficacy in no-till systems depends,in part, on rainfall to wash the herbicide onto the soil. Tillage and cover crop residue may also influence degradation of a herbicide in soil. This series of studies examined Cotoran (fluometuron, N,N ­ dimethyl-Nr-(3-(trifluoromethyl)phenyl) urea) wash- off from native vegetation,

L. A. Gaston; D. J. Boquet; S. D. Dotch; M. A. Bosch

268

Nitrogen mineralization and availability of mixed leguminous and non-leguminous cover crop residues in soil  

Microsoft Academic Search

Whereas non-leguminous cover crops such as cereal rye (Secale cereale) or annual ryegrass (Lolium multiflorium) are capable of reducing nitrogen (N) leaching during wet seasons, leguminous cover crops such as hairy vetch (Vicia villosa) improve soil N fertility for succeeding crops. With mixtures of grasses and legumes as cover crop, the goal of reducing\\u000a N leaching while increasing soil N

S. Kuo; U. M. Sainju

1998-01-01

269

Analysis of soil organic carbon and vegetation cover trends along the Botswana Kalahari Transect  

Microsoft Academic Search

Determination of trends in soil organic carbon (SOC) and vegetation cover along savanna ecosystem moisture gradients is critical to the understanding of ecosystem functioning and global change. Field results from 57 sites along the Botswana Kalahari Transect (BKT) showed general increases in both SOC and vegetation cover components along the temperature\\/moisture gradient. However, details in both SOC and woody cover

Susan Ringrose; Wilma Matheson; Cornelis Vanderpost

1998-01-01

270

Management of cruciferous cover crops by mowing for soil and water conservation in southern Spain  

Microsoft Academic Search

In recent years, the use of cover crops in Mediterranean olive orchards has increased due to serious soil erosion problems and surface water contamination by herbicides. In these areas, the annual precipitation regime is strongly seasonal, with dry summers that require killing the cover crop before it competes with the trees for water. Cruciferous species are being introduced as cover

C. Alcántara; A. Pujadas; M. Saavedra

2011-01-01

271

Effect of Cover Types and Soils on Runoff in  

Microsoft Academic Search

Hydrologic and meteorologic data for individual storms were collected from small headwater catchments representing three types of cover in northern Mississippi during 1958. Surface runoff and peak flows were greatest from abandoned fields, intermediate from depleted upland hardwood forests, and least from 20-year-old loblolly pine plantations that had been established on eroding farm land. The pine cover has been a

S. J. URSlC; J. L. THAMES

1960-01-01

272

Numerical modeling of soil covers for mine waste rock  

NASA Astrophysics Data System (ADS)

This project consists of studying some key hydrogeological properties of mine waste rocks and cover materials. The main objective was to evaluate the factors that influence flow of water in these materials, and to be able to improve the characterisation methods using numerical models. To do so, field work was completed on a waste rock pile of a mining operation in the southwest United States. Following this, a series of laboratory tests was done on samples of waste rock and of a potential cover material. Using these results, numerical calculations were performed to investigate the unsaturated flow conditions in the pile, for various configurations and properties. The numerical models, which were based on a typical geometry of waste rock dumps, show that the water entry value of the materials can play an important role in the amount of infiltration into the waste rock. The efficiency of covers was also investigated through these calculations. For a semi-arid climate, such as the one observed on the mine site, it is common to use the cover to try to limit water inflow (as opposed to limiting the oxygen flux) into potentially acid generating waste rock. A "Store, Divert and Release" cover (SDR) can typically be used to meet this objective. Different cover configurations have been studied, including a monolayer built with overburden from the mine site, and a multilayered cover composed of a coarse-grained material sandwiched between two layers of fine-grained material. The main results are presented and discussed in the paper.

Martin, V.; Aubertin, M.; Bussière, B.; Chapuis, R.

2004-05-01

273

Greenland soil bacteria & biogeochemistry: a vegetation cover proxy for climate warming effects  

NASA Astrophysics Data System (ADS)

Climate warming in the high Arctic is expected to increase plant biomass, deepen thaw, and stimulate decomposition of soil organic matter. However, it remains unclear how warming, plant growth, and microbial processing will interact to drive Arctic carbon and nutrient cycling. For example, greater plant growth should increase carbon storage in the ecosystem; however, increasing plant C inputs and thawing permafrost carbon should stimulate microbial biomass, potentially causing soil respiration to outpace storage. Alternatively, greater plant cover may lower soil temperature through shading, potentially curtailing the predicted increase in microbial activity. To evaluate microbial responses to climate warming in the high Arctic, we characterized the soil bacterial community and related soil biogeochemical properties, including pH, temperature, moisture, bulk density, extractable nutrient pools, extractable organic carbon and nitrogen, and total microbial biomass along a vegetation cover gradient in northwest Greenland. Vegetation cover was classified using the Normalized Difference Vegetation Index (NDVI), and vegetation cover classes were used as a proxy for changes associated with warming. We found that soil moisture increased and soil temperature decreased significantly with vegetation cover; moisture and temperature were higher in organic than in mineral horizons. Extractable nutrients (NO3-, NH4+, PO43-) and extractable organic C and N generally increased with vegetation cover and are higher in organic than in mineral horizons within a given vegetation class, with the exception of NO3-, which was comparable between horizons. Despite increases in available carbon and nutrients, microbial biomass carbon in both horizons ultimately decreased with vegetation cover, as did microbial biomass nitrogen in the mineral horizon. Moreover, the relative proportion of microbial biomass carbon to extractable organic carbon decreased with vegetation cover, indicating that decomposers in more vegetated soils do not readily use available carbon. Our results suggest that despite an increase in available substrate in high vegetation cover soils, the insulating properties of vegetation ultimately limit decomposer activity. We hypothesize that as plant cover in the high Arctic increases with climate warming, nutrient mineralization - initially heightened by higher temperatures - will ultimately be curtailed by the insulating properties of vegetation, leading to decreased nutrient availability to plants and a decline in plant cover until soils warm and dry to reach conditions more optimal for microbial processing. Following oscillations between higher and lower vegetation cover, soils may ultimately return to a 'baseline' moderate vegetation cover.

Dowdy, K. L.; Sistla, S.; Buckeridge, K. M.; Schimel, J.; Schaeffer, S. M.

2013-12-01

274

Migration and methanogens: A review of current landfill gas field research at ANL  

SciTech Connect

Landfill gas recovery research at Argonne National Laboratory is focusing on a project studying gas movement through landfill cover materials and a pilot investigation of microbial populations in landfills. Vertical gas pressure and concentration gradients between the top of refuse and the landfill cover are being examined. In particular, changes in the vertical gradients indicative of changes in magnitude and direction of pressure or diffusional flow with time are being monitored. This study emphasizes changes in vertical pressure and concentration gradients related to barometric pressure and other meteorological variables, soil moisture changes, and pumping rates at simulated recovery wells. Preliminary results suggest that changes in soil-gas pressures in the landfill cover and top of refuse closely follow changes in barometric pressure. Measurable concentration gradients exist between the top of refuse and the cover materials indicating that diffusion is a major mechanism for gas movement, particularly during dry weather when pressure gradients are negligible. A pilot investigation has begun on microbial populations in sanitary landfills. First, a series of leachate samples from various depths at the Blackwell Forest Preserve Landfill were evaluated for microbial populations, selected chemical constituents, and methane production. Diverse motile populations of fluorescing organisms were found in selected samples. 19 refs., 6 figs., 3 tabs.

Bogner, J.; Torpy, M.; Rose, C.; Vogt, M.; Gartman, D.; Moore, C.

1986-01-01

275

Effects of snow-cover on annual and seasonal soil respiration from a temperate mountain forest soil  

NASA Astrophysics Data System (ADS)

Climate change will alter the duration and magnitude of snow cover, especially in temperate areas at lower altitude, where wintertime air temperatures often fluctuate around freezing. A five years time series of consecutive soil respiration measurements was used to assess the effects of duration and magnitude of cold season snow-cover on annual and seasonal soil CO2 efflux. The temperature sensitivity of soil CO2 efflux during the cold season was assessed from seasonal data as well as from high frequency measurements during periods when air/soil temperatures showed high fluctuation. Substrate limitation as a potential driver of soil CO2 efflux during the cold season was tested by periodic amendment of sucrose followed by measurement and determination of the isotopic signature (13C) of the substrate induced soil respiration in the field. First results will be presented at the conference.

Schindlbacher, Andreas; Jandl, Robert; Schindlbacher, Sabine

2013-04-01

276

Sanitary Landfilling.  

National Technical Information Service (NTIS)

Contents: Introductory remarks; panel a: selecting sanitary landfill sites; how to select and acquire a sanitary landfill site; effects of industrial and hazardous wastes on site location; designing a rural sanitary landfill system; panel b: sanitary land...

J. E. Delaney

1973-01-01

277

Soil vapor survey at the LLNL site 300 general services area, adjacent portions of the Connolly and Gallo Ranches and the site 300 landfill pit 6 area  

Microsoft Academic Search

During October through December 1988, a soil vapor survey was conducted by Weiss Associates at the Lawrence Livermore National Laboratory Site 300 General Services Area (GSA), adjacent portions of the Connolly and Gallo Ranches, and at the Site 300 Landfill Pit 6 area. The purpose of the investigation was to aid in identifying the sources and the extent of trichloroethylene

S. Vonder Haar; J. Pavletich; W. McIlvride; M. Taffet

1989-01-01

278

Effects of vegetation cover on the microwave radiometric sensitivity to soil moisture  

NASA Technical Reports Server (NTRS)

The reduction in sensitivity of the microwave brightness temperature to soil moisture content due to vegetation cover is analyzed using airborne observations made at 1.4 and 5 GHz. The data were acquired during six flights in 1978 over a test site near Colby, Kansas. The test site consisted of bare soil, wheat stubble, and fully mature corn fields. The results for corn indicate that the radiometric sensitivity to soil moisture S decreases in magnitude with increasing frequency and with increasing angle of incidence (relative to nadir). The sensitivity reduction factor, defined in terms of the radiometric sensitivities for bare soil and canopy-covered conditions Y = 1 - Scan/Ss was found to be equal to 0.65 for normal incidence at 1.4 GHz, and increases to 0.89 at 5 GHz. These results confirm previous conclusions that the presence of vegetation cover may pose a serious problem for soil moisture detection with passive microwave sensors.

Ulaby, F. T.; Dobson, M. C.; Razani, M.

1983-01-01

279

Changes of Soil Microbial Biomass Carbon and Nitrogen with Cover Crops and Irrigation in a Tomato Field  

Microsoft Academic Search

In order to understand how soil microbial biomass was influenced by incorporated residues of summer cover crops and by water regimes, soil microbial biomass carbon (C) and nitrogen (N) were investigated in tomato field plots in which three leguminous and a non-leguminous cover crop had been grown and incorporated into the soil. The cover crops were sunn hemp (Crotalaria juncea

Q. R. Wang; Y. C. Li; W. Klassen

2007-01-01

280

Pendimethalin Wash?Off from Cover Crop Residues and Degradation in a Loessial Soil  

Microsoft Academic Search

Tillage and cover crops affect soil biological, chemical and physical properties that control the fate of herbicides in soil. Effects of conventional tillage (CT) and no tillage (NT) and either native winter annual vegetation, hairy vetch (Vicia villosa) or wheat (Triticum aestivum) on degradation of pendimethalin [N?(1?ethylpropyl)?3,4?dimethyl?2,6?dinitrobenzenamine] were investigated. Effect of pendimethalin sorption on residues of these cover crops on

L. A. Gaston; D. J. Boquet; M. A. Bosch

2003-01-01

281

Methane oxidation at a surface-sealed boreal landfill.  

PubMed

Methane oxidation was studied at a closed boreal landfill (area 3.9 ha, amount of deposited waste 200,000 tonnes) equipped with a passive gas collection and distribution system and a methane oxidative top soil cover integrated in a European Union landfill directive-compliant, multilayer final cover. Gas wells and distribution pipes with valves were installed to direct landfill gas through the water impermeable layer into the top soil cover. Mean methane emissions at the 25 measuring points at four measurement times (October 2005-June 2006) were 0.86-6.2 m(3) ha(-1) h(-1). Conservative estimates indicated that at least 25% of the methane flux entering the soil cover at the measuring points was oxidized in October and February, and at least 46% in June. At each measurement time, 1-3 points showed significantly higher methane fluxes into the soil cover (20-135 m(3) ha(-1) h(-1)) and methane emissions (6-135 m(3) ha(-1) h(-1)) compared to the other points (< 20 m(3) ha(-1) h(-1) and < 10 m(3) ha(-1) h(-1), respectively). These points of methane overload had a high impact on the mean methane oxidation at the measuring points, resulting in zero mean oxidation at one measurement time (November). However, it was found that by adjusting the valves in the gas distribution pipes the occurrence of methane overload can be to some extent moderated which may increase methane oxidation. Overall, the investigated landfill gas treatment concept may be a feasible option for reducing methane emissions at landfills where a water impermeable cover system is used. PMID:19264471

Einola, Juha; Sormunen, Kai; Lensu, Anssi; Leiskallio, Antti; Ettala, Matti; Rintala, Jukka

2009-07-01

282

Analysis of observed soil moisture patterns under different land covers in Western Ghats, India  

NASA Astrophysics Data System (ADS)

SummaryAn understanding of the soil moisture variability is necessary to characterize the linkages between a region's hydrology, ecology and physiography. In the changing land use scenario of Western Ghats, India, where deforestation along with extensive afforestation with exotic species is being undertaken, there is an urgent need to evaluate the impacts of these changes on regional hydrology. The objectives of the present study were: (a) to understand spatio-temporal variability of soil water potential and soil moisture content under different land covers in the humid tropical Western Ghats region and (b) to evaluate differences if any in spatial and temporal patterns of soil moisture content as influenced by nature of land cover. To this end, experimental watersheds located in the Western Ghats of Uttara Kannada District, Karnataka State, India, were established for monitoring of soil moisture. These watersheds possessed homogenous land covers of acacia plantation, natural forest and degraded forest. In addition to the measurements of hydro-meteorological parameters, soil matric potential measurements were made at four locations in each watershed at 50 cm, 100 cm and 150 cm depths at weekly time intervals during the period October 2004-December 2008. Soil moisture contents derived from potential measurements collected were analyzed to characterize the spatial and temporal variations across the three land covers. The results of ANOVA ( p < 0.01, LSD) test indicated that there was no significant change in the mean soil moisture across land covers. However, significant differences in soil moisture with depth were observed under forested watershed, whereas no such changes with depth were noticed under acacia and degraded land covers. Also, relationships between soil moisture at different depths were evaluated using correlation analysis and multiple linear regression models for prediction of soil moisture from climatic variables and antecedent moisture condition were developed and tested. A regression model relating near-surface soil moisture (50 cm) with profile soil moisture content was developed which may prove useful when surface soil moisture contents derived from satellite remote sensing are available. Overall results of this study indicate that while the nature of land cover has an influence on the spatio-temporal variability of soil moisture, other variables related to topography may have a more dominant effect.

Venkatesh, B.; Lakshman, Nandagiri; Purandara, B. K.; Reddy, V. B.

2011-02-01

283

Winter cover crops in a vegetable cropping system: Impacts on nitrate leaching, soil water, crop yield, pests and management costs  

Microsoft Academic Search

Plant-soil relationships in the surface soil layer affect other processes in agroecosystems, including crop productivity, nitrate leaching and plant-pest interactions. This study investigated the effect of altering surface soil dynamics, using a winter cover crop rotation, on biotic and abiotic characteristics of the soil profile. Two cover crop treatments, phacelia and Merced rye (Phacelia tanacetifolia cv. ‘Phaci’, and Secale cereale

L. J. Wyland; L. E. Jackson; W. E. Chaney; K. Klonsky; S. T. Koike; B. Kimple

1996-01-01

284

Impact of cover crops and tillage on porosity of podzolic soil  

NASA Astrophysics Data System (ADS)

The aim of the study was to determine the influence of cover crops biomass, mixed with the soil on different dates and with the use of different tools in field conditions. The cover crop biomass had a beneficial influence on the total porosity of the 0-20 cm layer of the soil after winter. The highest porosity was achievedwith cover crops of buckwheat, phacelia and mustard, the lowest with rye. During the vegetation period the highest porosity of soil was observed in the ridges. Among the remaining non-ploughing cultivations, pre-winter use of stubble cultivator proved to have a beneficial influence on the soil porosity, providing results comparable to those achieved in conventional tillage. The differential porosity of the soil was modified not only by the catch crops and the cultivation methods applied, but also by the sample collection dates, and it did change during the vegetation period. The highest content of macropores after winter was observed for the phacelia cover crop, and the lowest in the case of cultivation without any cover crops. Pre-winter tillage with the use of a stubble cultivator increased the amount of macropores in soil in spring, and caused the biggest participation of mesopores as compared with other non-ploughing cultivation treatments of the soil. The smallest amount of mesopores was found in the ridges.

B?a?ewicz-Wo?niak, M.; Konopiñski, M.

2013-09-01

285

Influence of Herbicide-Desiccated Cover Crops on Biological Soil Quality in the Mississippi Delta  

Microsoft Academic Search

The effect of crop residue management (CRM) systems on selected biological properties (microbial biomass\\/populations and soil enzyme activity) of Dundee soils under two cropping systems was investigated. In a cotton (Gossypium hirsutum L.) study, the influence of conventional tillage (CT) and no-tillage (NT) with and without an annual ryegrass cover crop (Lolium multiforum Lam.) on these properties was determined. Annual

S. C. Wagner; R. M. Zablotowicz; M. A. Locke; R. J. Smeda; C. T. Bryson

286

TOMATO YIELD AND SOIL QUALITY AS INFLUENCED BY TILLAGE, COVER CROPPING, AND NITROGEN FERTILIZATION  

Microsoft Academic Search

Tomato yield and soil quality may be influenced by management practices and climatic conditions. We examined the effects of tillage (no-till, chisel plowing, and moldboard plowing), cover crop (hairy vetch (Vicia villosa Roth) and no hairy vetch), and N fertilization (0, 80, and 160 lb N acre-1) on tomato yield and N uptake, root growth, and soil C and N

Upendra M. Sainju; Bharat P. Singh; Sidat Yaffa

287

Cover crop and tillage effects on soil enzyme activities following tomato  

Microsoft Academic Search

Increasing numbers of vegetable growers are adopting conservation tillage practices and including cover crops into crop rotations. The practice helps to increase or maintain an adequate level of soil organic matter and improves vegetable yields. The effects of the practices, however, on enzyme activities in southeastern soils of the United States have not been well documented. Thus, the objectives of

Said A. Hamido; K. Kpomblekou-A

2009-01-01

288

Effects of Vegetation Cover on the Microwave Radiometric Sensitivity to Soil Moisture  

Microsoft Academic Search

The reduction in sensitivity of the microwave brightness temperature to soil moisture content due to vegetation cover is analyzed using airborne observations made at 1.4 and 5 GHz. The data were acquired during six flights in 1978 over a test site near Colby, Kansas. The test site consisted of bare soil, wheat stubble, and fully mature corn fields. The results

Fawwaz T. Ulaby; Mohammad Razani; Myron C. Dobson

1983-01-01

289

Landfill gas generation and migration: Review of current research II  

SciTech Connect

With regard to gas migration, a field investigation is examining bidirectional gas movement through landfill cover materials by processes of pressure and diffusional flow. The overall purpose of the study is to quantify gas loss from the landfill reservoir by natural venting and air influx due to pumping on recovery wells. Two field sites--a humid site, with vegetated clay cover and a semiarid site with unvegetated sandy silt cover--have been instrumented to examine vertical gas movement through cover materials. Results from the past year's work at the semiarid site indicates that rates of CH/sub 4/ flux out of the landfill surface may be as high as 2 /times/ 10/sup /minus/6/ g cm/sup /minus/2/ sec/sup /minus/1/ (6.3 /times/ 10/sup 2/ Kg m/sup /minus/1/ yr/sup /minus/1/) during dry soil conditions. Such high rates represent both the loss of an energy resource and a significance factor in global warming trends since atmospheric CH/sub 4/ contributes to the greenhouse effect. An independent estimate has suggested that 8--15% of global atmospheric CH/sub 4/ is attributable to landfill sources. The second project is addressing landfill gas generation. The major goal is to develop simple assay techniques to examine the gas production potential of landfilled refuse. Refuse samples extracted from various depths in a landfill are being subjected to Biochemical Methane Production (BMP) assays with periodic qualitative examination of microbial populations. Triplicate assays of unamended refuse (controls) are compared to assays with added moisture, nutrients, and bacterial seed. To date, moisture addition is the single most important variable in stimulating gas production, particularly in samples with visible soil content. 56 refs., 2 figs., 3 tabs.

Bogner, J.; Vogt, M.; Piorkowski, R.

1989-01-01

290

Changes in soil properties and soil cover structure due to intensive erosion and accumulation processes in loess soils  

NASA Astrophysics Data System (ADS)

Intensive water and tillage erosion and consequent accumulation are the most important processes affecting the agroecosystems in loess regions and changing soil properties, e.g. organic carbon content, carbonate content or structure stability, and general distribution of soil units in the landscape. South Moravian loess belt, formerly covered mostly by Haplic Chernozem, is now formed by a highly diversified soil mosaic. At a morphologically heterogenous study plot (6 ha), a study on relationship between soil properties and terrain characteristics was held. DTM analysis, detailed terrain survey and laboratory analysis were the main methods adopted in the study. Three main soil units were identified: Haplic Chernozem, calcareous Regosol and Colluvial soil. The distribution of each soil unit correlates with different terrain attributes. Regosols are significatly connected to the steep slope, while their correlation with the curvature or hydrological indexes is lower. On the contrary, the Colluvial soils distribution depends mainly on values of curvature and topographical wetness index and is independent on the slope. Chernozem is related to a specific terrain position more than to any of the terrain attributes. Soil depth and humus horizon thickness vary extremelly - from 0.2 m at the erosionally exposed slopes to more than 2.5 m at the concave parts and the toeslope. Soil depth is significantly correlated with all of the tested terrain attributes except of the slope - the strongest correlation was proved in case of mean curvature, topographical wetness index and catchment area. Different degree of changes in particular soil properties results from the specificity of both erosion process and parent material character. Organic carbon content in the topsoil varies significantly. Humus is practically absent in the steepest parts of the slope where the loess is exposed. High amounts of Corg were identified in the undisturbed A horizons of the Chernozem unit. In the concave parts of the slope and at the toeslope, the Corg content in the plough layer is lower due to an admixture of non-humus material transported from the steep parts of the plot. Nevertheless, the deeper (0.7 - 2 m), buried parts of the colluvial profiles are very rich in organic carbon (up to 4 %). These horizons may represent fossil chernic horizons of former Chernozems, buried by intensive sedimentation of humic material. Similar variability was found in carbonate content values, always due to amount of loess admixture in the plough horizon. While the soil structure stability, depending strongly on humus content, was the highest in the Chernozem unit, in the eroded parts it was highly unstable. Changes in the cation exchange capacity and pH are less distinctive. CEC slightly increases in humus-rich soils and pH is higher in the eroded parts of the plot due to the loess exposition. Acknowledgement: Authors acknowledge the financial support of the Grant Agency of the Czech Republic (grant No. GA CR 526/08/0434) and the Ministry of Education, Youth and Sports of the Czech Republic (grant No. MSM 6046070901).

Zadorova, Tereza; Penizek, Vit; Jaksik, Ondrej; Kodesova, Radka; Jirku, Veronika; Fer, Miroslav

2010-05-01

291

Differentiation of the soil cover in the lower Ob River valley  

Microsoft Academic Search

Specific features of the soil cover in the lower reaches of the Ob River are analyzed. The physicochemical properties and\\u000a composition of the floodplain soils in different parts of the valley and on different floodplain elements are given. A comparative\\u000a geographical analysis of the accumulation of macro-and microelements in the floodplain soils as a result of alluviation processes\\u000a in the

E. G. Nechaeva

2008-01-01

292

Controls of biological soil crust cover and composition shift with succession in sagebrush shrub-steppe  

USGS Publications Warehouse

Successional stage may determine strength and causal direction of interactions among abiotic and biotic factors; e.g., species that facilitate the establishment of other species may later compete with them. We evaluated multivariate hypotheses about abiotic and biotic factors shaping biological soil crusts (BSCs) in early and late successional stages. We surveyed vegetation and BSC in the shrub-steppe ecosystem of the Columbia Basin. We analyzed the relationships with bryophyte and lichen covers using structural equation models, and analyzed the relationships with BSC composition using Indicator Species Analysis and distance-based linear models. Cover, indicator species, and composition varied with successional stage. Increasing elevation and bryophyte cover had higher lichen cover early in succession; these relationships were negative in the later successional stage. Lichen cover did not appear to impede B. tectorum cover, but B. tectorum appeared to strongly negatively affect lichen cover in both stages. Biological soil crust composition varied with bunchgrass cover in the early successional stage, but with elevation and B. tectorum cover later in succession. Our findings support the hypotheses that as succession progresses, the strength and direction of certain community interactions shift, and B. tectorum leads to reductions in biological soil crust cover regardless of successional stage.

Dettweiler-Robinson, E.; Bakker, J. D.; Grace, J. B.

2013-01-01

293

Leaky Landfills.  

ERIC Educational Resources Information Center

Provides background information on landfills and describes an activity where students learn how a modern landfill is constructed and develop an understanding of the reasons for several regulations regarding modern landfill construction. Students design and construct working models of three types of landfills. (PR)

Jones, Linda L. Cronin

1992-01-01

294

Gas production and migration in landfills and geological materials  

NASA Astrophysics Data System (ADS)

Landfill gas, originating from the anaerobic biodegradation of the organic content of waste, consists mainly of methane and carbon dioxide, with traces of volatile organic compounds. Pressure, concentration and temperature gradients that develop within the landfill result in gas emissions to the atmosphere and in lateral migration through the surrounding soils. Environmental and safety issues associated with the landfill gas require control of off-site gas migration. The numerical model TOUGH2-LGM (Transport of Unsaturated Groundwater and Heat-Landfill Gas Migration) has been developed to simulate landfill gas production and migration processes within and beyond landfill boundaries. The model is derived from the general non-isothermal multiphase flow simulator TOUGH2, to which a new equation of state module is added. It simulates the migration of five components in partially saturated media: four fluid components (water, atmospheric air, methane and carbon dioxide) and one energy component (heat). The four fluid components are present in both the gas and liquid phases. The model incorporates gas-liquid partitioning of all fluid components by means of dissolution and volatilization. In addition to advection in the gas and liquid phase, multi-component diffusion is simulated in the gas phase. The landfill gas production rate is proportional to the organic substrate and is modeled as an exponentially decreasing function of time. The model is applied to the Montreal's CESM landfill site, which is located in a former limestone rock quarry. Existing data were used to characterize hydraulic properties of the waste and the limestone. Gas recovery data at the site were used to define the gas production model. Simulations in one and two dimensions are presented to investigate gas production and migration in the landfill, and in the surrounding limestone. The effects of a gas recovery well and landfill cover on gas migration are also discussed.

Nastev, Miroslav; Therrien, René; Lefebvre, René; Gélinas, Pierre

2001-11-01

295

A new approach to quantifying soil temperature responses to changing air temperature and snow cover  

NASA Astrophysics Data System (ADS)

Seasonal snow cover provides an effective insulating barrier, separating shallow soil (0.25 m) from direct localized meteorological conditions. The effectiveness of this barrier is evident in a lag in the soil temperature response to changing air temperature. The causal relationship between air and soil temperatures is largely because of the presence or absence of snow cover, and is frequently characterized using linear regression analysis. However, the magnitude of the dampening effect of snow cover on the temperature response in shallow soils is obscured in linear regressions. In this study the author used multiple linear regression (MLR) with dummy predictor variables to quantify the degree of dampening between air and shallow soil temperatures in the presence and absence of snow cover at four Greenland sites. The dummy variables defining snow cover conditions were z = 0 for the absence of snow and z = 1 for the presence of snow cover. The MLR was reduced to two simple linear equations that were analyzed relative to z = 0 and z = 1 to enable validation of the selected equations. Compared with ordinary linear regression of the datasets, the MLR analysis yielded stronger coefficients of multiple determination and less variation in the estimated regression variables.

Mackiewicz, Michael C.

2012-08-01

296

Evidence for an underground runoff and soil permeability at the Ouled Fayet (Algiers, Algeria) buried waste pilot project: needs for a specific landfill implantation code  

NASA Astrophysics Data System (ADS)

Results from geophysical investigations (electrical resistivity, electromagnetic mapping and seismic refraction) on an empty excavated rack of the Ouled Fayet (Algiers, Algeria) pilot landfill evidenced a more permeable soil than found by a feasibility study and the presence of an underground runoff underneath the rack. The problem was to evaluate the degree of confidence of the feasibility study, based on 76 10-m drilling cores only, 6 of them performed on the studied rack. To the contrary of what is claimed in the feasibility study a threat of lixiviate pollution is real. It is more than urgent to elaborate a code for landfill implantation in Algeria, which should include mandatory geophysical prospecting and deeper drilling cores. Keywords: Landfill, Geophysical prospecting, Underground runoff, Permeability, Algeria.

Djadia, Leila; Abtout, Abdslam; Boudella, Amar

2014-05-01

297

Ammonia volatilization, N(2)O and CO(2) emissions from landfill leachate-irrigated soils.  

PubMed

Effects of leachate addition on ammonia volatilization and N(2)O and CO(2) emissions from two different soils were investigated using the 10-day laboratory incubation method at two levels of moisture content. Ammonia volatilization was dominated by soil pH and only occurred in alkaline clay soil, where 0.26-0.32% of soil ammonia could be lost. The N(2)O emission from the alkaline clay soil was one order of magnitude greater than that from the acidic sandy soil, when either water or leachate was irrigated. Increasing the moisture content from 46% water-filled pore space (WFPS) to 70% WFPS in the alkaline clay soil or the acidic sandy soil by either water or leachate irrigation increased the N(2)O emission by over twofold. The CO(2) emission from each soil sample at the two WFPSs was almost the same. The CO(2) emission from the alkaline clay soil with leachate addition was 72% lower than that from the acidic sandy soil with leachate addition, and 6.7 times higher than that from the alkaline clay soil with distilled water addition. Ammonia volatilization and N(2)O emission under leachate irrigation could be minimized by avoiding the excessively wet condition and by selecting the acidic sandy soil with low organic carbon and total nitrogen content. PMID:19773152

Zhang, Hou-Hu; He, Pin-Jing; Shao, Li-Ming

2010-01-01

298

Mitigating methane emissions and air intrusion in heterogeneous landfills with a high permeability layer.  

PubMed

Spatially variable refuse gas permeability and landfill gas (LFG) generation rate, cracking of the soil cover, and reduced refuse gas permeability because of liquid addition can all affect CH(4) collection efficiency when intermediate landfill covers are installed. A new gas collection system that includes a near-surface high permeability layer beneath the landfill cover was evaluated for enhancing capture of LFG and mitigating CH(4) emissions. Simulations of gas transport in two-dimensional domains demonstrated that the permeable layer reduces CH(4) emissions up to a factor of 2 for particular spatially variable gas permeability fields. When individual macrocracks formed in the cover soil and the permeable layer was absent, CH(4) emissions increased to as much as 24% of the total CH(4) generated, double the emissions when the permeable layer was installed. CH(4) oxidation in the cover soil was also much more uniform when the permeable layer was present: local percentages of CH(4) oxidized varied between 94% and 100% across the soil cover with the permeable layer, but ranged from 10% to 100% without this layer for some test cases. However, the permeable layer had a minor effect on CH(4) emissions and CH(4) oxidation in the cover soil when the ratio of the gas permeability of the cover soil to the mean refuse gas permeability ? 0.05. The modeling approach employed in this study may be used to assess the utility of other LFG collection systems and management practices. PMID:20880688

Jung, Yoojin; Imhoff, Paul T; Augenstein, Don; Yazdani, Ramin

2011-05-01

299

Landfill mining: A critical review of two decades of research  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer We analyze two decades of landfill mining research regarding trends and topics. Black-Right-Pointing-Pointer So far landfill mining has mainly been used to solve waste management issues. Black-Right-Pointing-Pointer A new perspective on landfills as resource reservoirs is emerging. Black-Right-Pointing-Pointer The potential of resource extraction from landfills is significant. Black-Right-Pointing-Pointer We outline several key challenges for realization of resource extraction from landfills. - Abstract: Landfills have historically been seen as the ultimate solution for storing waste at minimum cost. It is now a well-known fact that such deposits have related implications such as long-term methane emissions, local pollution concerns, settling issues and limitations on urban development. Landfill mining has been suggested as a strategy to address such problems, and in principle means the excavation, processing, treatment and/or recycling of deposited materials. This study involves a literature review on landfill mining covering a meta-analysis of the main trends, objectives, topics and findings in 39 research papers published during the period 1988-2008. The results show that, so far, landfill mining has primarily been seen as a way to solve traditional management issues related to landfills such as lack of landfill space and local pollution concerns. Although most initiatives have involved some recovery of deposited resources, mainly cover soil and in some cases waste fuel, recycling efforts have often been largely secondary. Typically, simple soil excavation and screening equipment have therefore been applied, often demonstrating moderate performance in obtaining marketable recyclables. Several worldwide changes and recent research findings indicate the emergence of a new perspective on landfills as reservoirs for resource extraction. Although the potential of this approach appears significant, it is argued that facilitating implementation involves a number of research challenges in terms of technology innovation, clarifying the conditions for realization and developing standardized frameworks for evaluating economic and environmental performance from a systems perspective. In order to address these challenges, a combination of applied and theoretical research is required.

Krook, Joakim, E-mail: joakim.krook@liu.se [Department of Management and Engineering, Environmental Technology and Management, Linkoeping University, SE-581 83 Linkoeping (Sweden); Svensson, Niclas; Eklund, Mats [Department of Management and Engineering, Environmental Technology and Management, Linkoeping University, SE-581 83 Linkoeping (Sweden)

2012-03-15

300

The influence of atmospheric pressure on landfill methane emissions.  

PubMed

Landfills are the largest source of anthropogenic methane (CH4) emissions to the atmosphere in the United States. However, few measurements of whole landfill CH4 emissions have been reported. Here, we present the results of a multi-season study of whole landfill CH4 emissions using atmospheric tracer methods at the Nashua, New Hampshire Municipal landfill in the northeastern United States. The measurement data include 12 individual emission tests, each test consisting of 5-8 plume measurements. Measured emissions were negatively correlated with surface atmospheric pressure and ranged from 7.3 to 26.5 m3 CH4 min(-1). A simple regression model of our results was used to calculate an annual emission rate of 8.4 x 10(6) m3 CH4 year(-1). These data, along with CH4 oxidation estimates based on emitted landfill gas isotopic characteristics and gas collection data, were used to estimate annual CH4 generation at this landfill. A reported gas collection rate of 7.1 x 10(6) m3 CH4 year(-1) and an estimated annual rate of CH4 oxidation by cover soils of 1.2 x 10(6) m3 CH4 year(-1) resulted in a calculated annual CH4 generation rate of 16.7 x 10(6) m3 CH4 year(-1). These results underscore the necessity of understanding a landfill's dynamic environment before assessing long-term emissions potential. PMID:12957154

Czepiel, P M; Shorter, J H; Mosher, B; Allwine, E; McManus, J B; Harriss, R C; Kolb, C E; Lamb, B K

2003-01-01

301

Hydraulic conductivity study of compacted clay soils used as landfill liners for an acidic waste.  

PubMed

Three natural clayey soils from Tunisia were studied to assess their suitability for use as a liner for an acid waste disposal site. An investigation of the effect of the mineral composition and mechanical compaction on the hydraulic conductivity and fluoride and phosphate removal of three different soils is presented. The hydraulic conductivity of these three natural soils are 8.5 × 10(-10), 2.08 × 10(-9) and 6.8 × 10(-10)m/s for soil-1, soil-2 and soil-3, respectively. Soil specimens were compacted under various compaction strains in order to obtain three wet densities (1850, 1950 and 2050 kg/m(3)). In this condition, the hydraulic conductivity (k) was reduced with increasing density of sample for all soils. The test results of hydraulic conductivity at long-term (>200 days) using acidic waste solution (pH=2.7, charged with fluoride and phosphate ions) shows a decrease in k with time only for natural soil-1 and soil-2. However, the specimens of soil-2 compressed to the two highest densities (1950 and 2050 kg/m(3)) are cracked after 60 and 20 days, respectively, of hydraulic conductivity testing. This damage is the result of a continued increase in the internal stress due to the swelling and to the effect of aggressive wastewater. The analysis of anions shows that the retention of fluoride is higher compared to phosphate and soil-1 has the highest sorption capacity. PMID:22980909

Hamdi, Noureddine; Srasra, Ezzeddine

2013-01-01

302

Differentiation of the soil cover in the lower Ob River valley  

NASA Astrophysics Data System (ADS)

Specific features of the soil cover in the lower reaches of the Ob River are analyzed. The physicochemical properties and composition of the floodplain soils in different parts of the valley and on different floodplain elements are given. A comparative geographical analysis of the accumulation of macro-and microelements in the floodplain soils as a result of alluviation processes in the middle and lower reaches of the Ob River is suggested. The evolution of the floodplain soils and the results of the development of stratified humus horizons, changes in the hydrological regime, and cessation of floods are discussed.

Nechaeva, E. G.

2008-11-01

303

Frequency and distribution patterns of zoosporic fungi from moss-covered and exposed forest soils.  

PubMed

Uniflagellate zoosporic "fungi" (=Chytridiomycota and the zoosporic protista Hyphochytriomycota) are common inhabitants of soil. However, at what scale differences in their spatial distribution can be detected is poorly known. The first objective of this study was to assess the association of organismal distribution and frequency with two microhabitats: moss-covered and exposed forest soils, at four macroscopically similar but spatially separate sites in the Blue Ridge and Allegheny Mountains of Virginia. The second objective was to provide statistically either acceptance or denial of inferences derived from sampling regimes involving a more limited number of samples. To evaluate the scale where distributional differences may occur within a site, protocols involved four collection regimes and random point and linear transect sampling. Chytrid frequency on thalli of two moss genera was greatest in the soil surrounding and under the moss rhizoids. Random point sampling methods suggested differences in zoosporic fungal frequency between moss-covered soil and the exposed soil adjacent to mosses, as well as between two moss taxa. Linear transect sampling methods also suggested differences in zoosporic fungal frequencies between moss-covered soil and soil proximal to mosses. However, statistical analysis of random point samples using a goodness-of-fit test demonstrated that there was no significant difference in frequency of zoosporic fungi from moss-covered soil and exposed soil proximal to mosses. More importantly, there was a significant difference in the frequency of ubiquitous and common zoosporic fungal species between different moss/soil complexes. This study demonstrates that differences in chytrid distribution can be detected at a microscale while at a larger scale, similarity in frequency and distribution was found. PMID:21156550

Letcher, Peter M; Powell, Martha J

2002-01-01

304

Landfill CH{sub 4}: Rates, fates, and role in global carbon cycle  

SciTech Connect

Published estimates for worldwide landfill methane emissions range from 9 to 70 Tg yr{sup {minus}1}. Field and laboratory studies suggest that maximum methane yields from lanfilled refuse are about 0.06 to 0.09 m{sup 3} (dry Kg){sup {minus}1} refuse, depending on moisture content and other variables, such as organic loading, buffering capacity, and nutrients in landfill microevnironments. Methane yields may vary by more than an order of magnitude within a given site. Fates for landfill methane include (1) direct or delayed emission to the atmosphere through landfill cover materials or surface soils; (2) oxidation by methanotrophs in cover soils, with resulting emission of carbon dioxide; or (3) recovery of methane followed by combustion to produce carbon dioxide. The percent methane assigned to each pathway will vary among field sites and, for individual sites, through time. Nevertheless, a general framework for a landfill methane balance can be developed by consideration of landfill age, engineering and management practices, cover soil characteristics, and water balance. Direct measurements of landfill methane emissions are sparse, with rates between 10{sup {minus}6} and 10{sup {minus}8} g cm{sup {minus}2} s{sup {minus}1}; very high rates of 400 kg m{sup {minus}2} yr{sup {minus}1} have been measured at a semiarid unvegetated site. The proportion of landfill carbon that is ultimately converted to methane and carbon dioxide is problematical; the literature suggests that, at best, 25% to 40% of refuse carbon can be converted to biogas carbon. Cellulose contributes the major portion of the methane potential. Routine excavation of nondecomposed cellulosic materials after one or two decades of landfill burial suggests that uniformly high conversion rates are rarely attained at field sites.

Bogner, J.; Spokas, K.

1991-12-31

305

Landfill CH sub 4 : Rates, fates, and role in global carbon cycle  

SciTech Connect

Published estimates for worldwide landfill methane emissions range from 9 to 70 Tg yr{sup {minus}1}. Field and laboratory studies suggest that maximum methane yields from lanfilled refuse are about 0.06 to 0.09 m{sup 3} (dry Kg){sup {minus}1} refuse, depending on moisture content and other variables, such as organic loading, buffering capacity, and nutrients in landfill microevnironments. Methane yields may vary by more than an order of magnitude within a given site. Fates for landfill methane include (1) direct or delayed emission to the atmosphere through landfill cover materials or surface soils; (2) oxidation by methanotrophs in cover soils, with resulting emission of carbon dioxide; or (3) recovery of methane followed by combustion to produce carbon dioxide. The percent methane assigned to each pathway will vary among field sites and, for individual sites, through time. Nevertheless, a general framework for a landfill methane balance can be developed by consideration of landfill age, engineering and management practices, cover soil characteristics, and water balance. Direct measurements of landfill methane emissions are sparse, with rates between 10{sup {minus}6} and 10{sup {minus}8} g cm{sup {minus}2} s{sup {minus}1}; very high rates of 400 kg m{sup {minus}2} yr{sup {minus}1} have been measured at a semiarid unvegetated site. The proportion of landfill carbon that is ultimately converted to methane and carbon dioxide is problematical; the literature suggests that, at best, 25% to 40% of refuse carbon can be converted to biogas carbon. Cellulose contributes the major portion of the methane potential. Routine excavation of nondecomposed cellulosic materials after one or two decades of landfill burial suggests that uniformly high conversion rates are rarely attained at field sites.

Bogner, J.; Spokas, K.

1991-01-01

306

Methanotroph diversity in landfill soil: Isolation of novel type I and type II methanotrophs whose presence was suggested by culture-independent 16S ribosomal DNA analysis  

SciTech Connect

The diversity of the methanotrophic community in mildly acidic landfill cover soil was assessed by three methods: two culture-independent molecular approaches and a traditional culture-based approach. For the first of the molecular studies, two primer pairs specific for the 16S rRNA gene of validly published type I (including for former type X) and type II methanotrophs were identified and tested. These primers were used to amplify directly extracted soil DNA, and the products were used to construct type I and type II clone libraries. The second molecular approach, based on denaturing gradient gel electrophoresis (DGGE), provided profiles of the methanotrophic community members as distinguished by sequence differences in variable region 3 of the 16S ribosomal DNA. For the culturing studies, an extinction-dilution technique was employed to isolate slow-growing but numerically dominant strains. The key variables of the series of enrichment conditions were initial pH (4.8 versus 6.8), air/CH{sub 4}/CO{sub 2} headspace ratio (50:45:5 versus 90:9:1), and concentration of the medium (1x nitrate minimal salts [NMS] versus 0.2x NMS). Screening of the isolates showed that the nutrient-rich 1x NMS selected for type I methanotrophs, which the nutrient-poor 0.2x NMS tended to enrich for type II methanotrophs. Partial sequencing of the 16S rRNA gene from selected clones and isolates revealed some of the same novel sequence types.

Wise, M.G.; McArthur, J.V.; Smimkets, L.J.

1999-11-01

307

Soil moisture and evapotranspiration of different land cover types in the Loess Plateau, China  

NASA Astrophysics Data System (ADS)

We studied the impacts of re-vegetation on soil moisture dynamics and evapotranspiration (ET) of five land cover types in the Loess Plateau in northern China. Soil moisture and temperature variations under grass (Andropogon), subshrub (Artemisia scoparia), shrub (Spiraea pubescens), plantation forest (Robinia pseudoacacia), and crop (Zea mays) vegetation were continuously monitored during the growing season of 2011. There were more than 10 soil moisture pulses during the period of data collection. Surface soil moisture of all of the land cover types showed an increasing trend in the rainy season. Soil moisture under the corn crop was consistently higher than the other surfaces. Grass and subshrubs showed an intermediate moisture level. Grass had slightly higher readings than those of subshrub most of the time. Shrubs and plantation forests were characterized by lower soil moisture readings, with the shrub levels consistently being slightly higher than those of the forests. Despite the greater post-rainfall loss of moisture under subshrub and grass vegetation than forests and shrubs, subshrub and grass sites exhibit a higher soil moisture content due to their greater soil retention capacity in the dry period. The daily ET trends of the forests and shrub sites were similar and were more stable than those of the other types. Soils under subshrubs acquired and retained soil moisture resources more efficiently than the other cover types, with a competitive advantage in the long term, representing an adaptive vegetation type in the study watershed. The interactions between vegetation and soil moisture dynamics contribute to structure and function of the ecosystems studied.

Wang, S.; Fu, B. J.; Gao, G. Y.; Yao, X. L.; Zhou, J.

2012-08-01

308

Using high-resolution radar images to determine vegetation cover for soil erosion assessments.  

PubMed

Healthy soils are crucial for human well-being. Because soils are threatened worldwide, politicians recognize the need for soil protection. For example, the European Commission has launched the Thematic Strategy for Soil Protection, which requests the European member states to identify high risk areas for soil degradation. Most states use the Universal Soil Loss Equation (USLE) to assess soil erosion risk at the national scale. The USLE includes different factors, one of them is the vegetation cover and management factor (C factor). Modern satellite-based radar sensors now provide highly accurate vegetation cover data, enabling opportunities to improve the accuracy of the C factor. The presented study proves the suitability for C factor determination based on a multi-temporal classification of high-resolution radar images. Further USLE factors were derived from existing data sources (meteorological data, soil maps, digital elevation model) to conduct an USLE-based soil erosion assessment. The resulting map illustrates a qualitative assessment for soil erosion risk within a plot of about 7*12 km in an agricultural region in Poland that is very susceptible to soil erosion processes. A high erosion risk of more than 10 tonnes per ha and year was assessed to occur on 13.6% (646 ha) of the agricultural areas within the investigated plot. Further 7.8% (372 ha) of agricultural land is threaten by a medium risk of 5-10 tonnes per ha and year. Such a spatial information about areas of high or medium soil erosion risk are crucial for the development of strategies for the protection of soils. PMID:23624425

Bargiel, D; Herrmann, S; Jadczyszyn, J

2013-07-30

309

Effect of land-use practice on soil moisture variability for soils covered with dense forest vegetation of Puerto Rico  

NASA Technical Reports Server (NTRS)

Little is known about the landuse management effect on soil moisture and soil pH distribution on a landscape covered with dense tropical forest vegetation. This study was conducted at three locations where the history of the landuse management is different. Soil moisture was measured using a 6-cm three-rod Time Domain Reflectometery (TDR) probe. Disturbed soil samples were taken from the top 5-cm at the up, mid, and foothill landscape position from the same spots where soil moisture was measured. The results showed that soil moisture varies with landscape position and depth at all three locations. Soil pH and moisture variability were found to be affected by the change in landuse management and landscape position. Soil moisture distribution usually expected to be relatively higher in the foothill (P3) area of these forests than the uphill (P1) position. However, our results indicated that in the Luquillo and Guanica site the surface soil moisture was significantly higher for P1 than P3 position. These suggest that the surface and subsurface drainage in these two sites may have been poor due to the nature of soil formation and type.

Tsegaye, T.; Coleman, T.; Senwo, Z.; Shaffer, D.; Zou, X.

1998-01-01

310

Paleo-shade: woody cover, stable isotopes, soil temperature, and soil organic matter in tropical ecosystems (Invited)  

NASA Astrophysics Data System (ADS)

The ?13C value of soil carbon is directly related to the fraction of C4 biomass in soils because of the difference in isotope discrimination between plants using the C3 (trees, shrubs, and herbs) and C4 (primarily tropical grasses) photosynthetic pathways. Almost all woody plants use the C3 photosynthetic pathway, and therefore the fraction of woody cover in tropical ecosystems has an important influence on the fraction of C4 biomass in soils. Surveys of tropical ecosystems from East Africa and Australia show that little C4 biomass is evident until woody cover fraction falls below 0.5. This is due to several factors, including the shading effect of woody cover and retention of soil moisture; these decrease the daily maximum ground surface temperature and decrease water stress. Thus, C3 photosynthesis is favored relative to C4 photosynthesis in well-shaded environments compared to nearby open environments. Between 0.0 and 0.5 fraction woody cover, the ?13C of soil organic matter is strongly correlated with the fraction of woody cover. However, as the woody cover approaches 0, in some semi-arid ecosystems a significant fraction of C3 herbaceous plants are present. Thus some “grasslands” may have a significant fraction of C3 herbaceous cover. Paleosols are an indicator of the fraction of C4 biomass because of their preserved ?13C values in organic matter and in pedogenic carbonate. This ?13C signal can be used as an indicator of “paleo-shade” or fraction of woody-cover in the geological record. ?47C values of paleosols for much of the past 4 Ma in the Turkana Basin in northern Kenya and the Awash Basin in Ethiopia indicate ecosystems similar to modern grasslands to woody grasslands (using the UNESCO classification for tropical ecosystems); these are commonly known as savannas. Thus some of the most important localities documenting hominin evolution show strong evidence for a savanna environment. This interpretation is supported by independent evidence from ‘carbonate clumped-isotope’ thermometry of Turkana Basin paleosol carbonates: this method reveals that deep (>50 cm) soil temperatures were ~30 - 35C during carbonate-forming intervals of the past 4 Ma, a temperature range significantly higher than temperatures of modern tropical forest soils, but similar to soil temperatures in open arid environments such as the present day Turkana Basin.

Cerling, T. E.; Andanje, S.; Kimutai, D.; Levin, N. E.; Mace, W. D.; Macharia, A. N.; Passey, B. H.; Remien, C.; Wynn, J. G.

2010-12-01

311

Effects of over-winter green cover on soil solution nitrate concentrations beneath tillage land.  

PubMed

There is a growing need to reduce nitrogen losses from agricultural systems to increase food production while reducing negative environmental impacts. The efficacy of vegetation cover for reducing nitrate leaching in tillage systems during fallow periods has been widely investigated. Nitrate leaching reductions by natural regeneration (i.e. growth of weeds and crop volunteers) have been investigated to a lesser extent than reductions by planted cover crops. This study compares the efficacy of natural regeneration and a sown cover crop (mustard) relative to no vegetative cover under both a reduced tillage system and conventional plough-based system as potential mitigation measures for reducing over-winter soil solution nitrate concentrations. The study was conducted over three winter fallow seasons on well drained soil, highly susceptible to leaching, under temperate maritime climatic conditions. Mustard cover crop under both reduced tillage and conventional ploughing was observed to be an effective measure for significantly reducing nitrate concentrations. Natural regeneration under reduced tillage was found to significantly reduce the soil solution nitrate concentrations. This was not the case for the natural regeneration under conventional ploughing. The improved efficacy of natural regeneration under reduced tillage could be a consequence of potential stimulation of seedling germination by the autumn reduced tillage practices and improved over-winter plant growth. There was no significant effect of tillage practices on nitrate concentrations. This study shows that over winter covers of mustard and natural regeneration, under reduced tillage, are effective measures for reducing nitrate concentrations in free draining temperate soils. PMID:24239817

Premrov, Alina; Coxon, Catherine E; Hackett, Richard; Kirwan, Laura; Richards, Karl G

2014-02-01

312

Numerical Modeling of the Soil Cover System Performance from Hydrogeological Analysis  

NASA Astrophysics Data System (ADS)

Decline of mining industry is drastic in production and consumption in Korea, and the number of operating mines has been reduced by more than 90 percent in last two decades. Environmental concern and the collapse of commercial viability has necessitated the government to close down uneconomical mines, and reclamation of mine waste dumps and the proper treatment of the mine drainage constitute the most important factors for regional rehabilitation programs. A dry soil cover system for mine waste is steadily increasing in Korea, to minimize the influx of water and oxygen into the waste dump. Traditional cover design procedures based on empirical or semi-quantitative analyses can be improved by implementing environmental and hydrological parameters including total precipitation, evapotranspiration, surface runoff, and infiltration associated with different cover configurations. The main objective of this study is to develop a standardized design procedure for dry cover systems to minimize environmental impacts in mine lands, securing both efficiency and long-term structural stability. A numerical analysis technique was adopted for selecting governing parameters which dictate hydrogeologic characteristics of the unsaturated zone in soil cover system. Variables included the soil water characteristic curve, hydraulic conductivity function, and water balance of the study area. A commercial finite element analysis software was applied for performance analysis of three soil cover systems including a simple growth medium, sand layer, and sand-clay-sand complex layer.

Min, D.; Cheong, Y.; Yim, G.; Baek, H.

2008-05-01

313

Effects of tillage and winter cover cropping on microbial substrate-induced respiration and soil aggregation in two Japanese fields  

Microsoft Academic Search

We hypothesized that cover cropping could increase soil microbial activities under various tillage systems and that increased microbial activities would improve soil properties. Soil sampling was conducted at two fields in Japan in 2009. At the Ibaraki field (Andosol, clay loam), three tillage practices (no-tillage, plowing to 30?cm, and rotary tillage to 15?cm) and three types of winter cover cropping

Tomomi Nakamoto; Masakazu Komatsuzaki; Toshiyuki Hirata; Hajime Araki

2012-01-01

314

Mitigating the effects of soil and residue water contents on remotely sensed estimates of crop residue cover  

Microsoft Academic Search

Crop residues on the soil surface decrease soil erosion and increase soil organic carbon and the management of crop residues is an integral part of many conservation tillage systems. Current methods of measuring residue cover are inadequate for characterizing the spatial variability of residue cover over large fields. The objectives of this research were to determine the effects of water

C. S. T. Daughtry; E HUNTJR

2008-01-01

315

Fluxes of methane between landfills and the atmosphere: Natural and engineered controls  

SciTech Connect

Field measurement of landfill methane emissions indicates natural variability spanning more than 2 seven orders of magnitude, from approximately 0.0004 to more than 4000 g m{sub -2} day{sup -1}. This wide range reflects net emissions resulting from production (methanogenesis), consumption (methanotrophic oxidation), and gaseous transport processes. The determination of an {open_quotes}average{close_quotes} emission rate for a given field site requires sampling designs and statistical techniques which consider spatial and temporal variability. Moreover, particularly at sites with pumped gas recovery systems, it is possible for methanotrophic microorganisms in aerated cover soils to oxidize all of the methane from landfill sources below and, additionally, to oxidize methane diffusing into cover soils from atmospheric sources above. In such cases, a reversed soil gas concentration gradient is observed in shallow cover soils, indicating bidirectional diffusional transport to the depth of optimum methane oxidation. Rates of landfill methane oxidation from field and laboratory incubation studies range up to 166 g m{sup -2} day{sup -1} among the highest for any natural setting, providing an effective natural control on net emissions. Estimates of worldwide landfill methane emissions to the atmosphere have ranged from 9 to 70 Tg yr{sup -1}, differing mainly in assumed methane yields from estimated quantities of landfilled refuse. At highly controlled landfill sites in developed countries, landfill methane is often collected via vertical wells or horizontal collectors. Recovery of landfill methane through engineered systems can provide both environmental and energy benefits by mitigating subsurface migration, reducing surface emissions, and providing an alternative energy resource for industrial boiler use, on-site electrical generation, or upgrading to a substitute natural gas.

Bogner, J. [Argonne National Lab., IL (United States); Meadows, M. [ETSU, Harwell, Oxfordshire (United Kingdom); Czepiel, P. [Harvard Univ., Cambridge, MA (United States)

1997-08-01

316

[Responses of net soil nitrogen mineralization rate in moss-covered soil to hydrothermic factors in Shapotou regions, northern China].  

PubMed

Undisturbed soil cores were incubated in laboratory at different temperatures (-10, 5, 15, 25, 35 and 40 degrees C) and moistures (29%, 58%, 85% and 170% of field water content, FWC) to analyze the effect of moss crusts, which were sampled from the natural vegetation area of Shapotou, on soil nitrogen transformation and their responses to hydrothermic factors. Results showed that immobilization was the dominant form of nitrogen transformation at the lower temperatures (<15 degrees C), and when the temperature surpassed 25 degrees C, the nitrogen transformation rate significantly increased. The nitrogen transformation rate in the moss-covered soil was more sensitive to temperature variation than in the bare soil, and the highest temperature sensitivity was at 85% FWC. It indicated that the existence and succession of moss crusts facilitated nitrogen transformation. In addition, the nitrogen transformation rates of two microhabitats increased initially and then declined with the increasing moisture, and the maximum nitrogen transformation rate was observed at 85% FWC. Significant interactive effects were found between temperature and moisture in the moss-covered soil. While, the greater enhancement in nitrogen transformation rate appeared at higher temperatures (25-40 degrees C ) and moderate moisture levels (58% FWC and 85% FWC). It was concluded that the existence and succession of moss crusts would increase the ability of soil nitrogen supply, promote nitrogen cycling and even contribute to the restoration of soil ecosystem. PMID:24830238

Hu, Rui; Wang, Xin-Ping; Pan, Yan-Xia; Zhang, Ya-Feng; Zhang, Ke; Zhang, Hao

2014-02-01

317

Soil microbial, fungal, and nematode responses to soil fumigation and cover crops under potato production  

Microsoft Academic Search

Sodium N-methyldithiocarbamate (metam sodium) and 1,3 dichloropropene are widely used in potato production for the control of soil-borne\\u000a pathogens, weeds, and plant parasitic nematodes that reduce crop yield and quality. Soil fumigation with metam sodium has\\u000a been shown in microcosm studies to significantly reduce soil microbial populations and important soil processes such as C\\u000a and N mineralization. However, few published

H. P. Collins; A. Alva; R. A. Boydston; R. L. Cochran; P. B. Hamm; A. McGuire; E. Riga

2006-01-01

318

Effects of landfill gas on subtropical woody plants  

NASA Astrophysics Data System (ADS)

An account is given of the influence of landfill gas on tree growth in the field at Gin Drinkers' Bay (GDB) landfill, Hong Kong, and in the laboratory. Ten species ( Acacia confusa, Albizzia lebbek, Aporusa chinensis, Bombax malabaricum, Castanopsis fissa, Liquidambar formosana, Litsea glutinosa, Machilus breviflora, Pinus elliottii, and Tristania conferta), belonging to eight families, were transplanted to two sites, one with a high concentration of landfill gas in the cover soil (high-gas site, HGS) and the other with a relatively low concentration of gas (low-gas site, LGS). Apart from the gaseous composition, the general soil properties were similar. A strong negative correlation between tree growth and landfill gas concentration was observed. A laboratory study using the simulated landfill gas to fumigate seedlings of the above species showed that the adventitious root growth of Aporusa chinensis, Bombax malabaricum, Machilus breviflora, and Tristania confera was stimulated by the gas, with shallow root systems being induced. Acacia confusa, Albizzia lebbek, and Litsea glutinosa were gas-tolerant, while root growth of Castanopsis fissa, Liquidambar formosana, and Pinus elliottii was inhibited. In most cases, shoot growth was not affected, exceptions being Bombax malabaricum, Liquidambar formosana, and Tristania conferta, where stunted growth and/or reduced foliation was observed. A very high CO2 concentration in cover soil limits the depth of the root system. Trees with a shallow root system become very susceptible to water stress. The effects of low O2 concentration in soil are less important than the effects of high CO2 concentration. Acacia confusa, Albizzia lebbek, and Tristania conferta are suited for growth on subtropical completed landfills mainly due to their gas tolerance and/or drought tolerance.

Chan, G. Y. S.; Wong, M. H.; Whitton, B. A.

1991-05-01

319

Soils and the soil cover of the arkaim reserve (Steppe Zone of the Trans-Ural Region)  

NASA Astrophysics Data System (ADS)

Soils of the Arkaim Reserve in the area around a unique settlement-fortress of the Bronze Age in Chelyabinsk oblast have been studied. These soils are generally typical of the entire Trans-Ural Plateau. The soil properties are characterized in detail on the basis of factual data on 170 soil pits and four soil catenas. The soil cover of the reserve is specified into six geomorphic groups: (a) denudational surfaces of the low mountains, (b) accumulative-denudational surfaces of the low mountains, (c) denudational-accumulative plain surfaces, (d) lacustrine-alluvial plain surfaces, (e) floodplain surfaces, and (f) slopes and bottoms of the local ravines and hollows. Chernozems occupy about 50% of the reserve; solonetzes and saline soils, 32%; meadow chernozems, 7%; and forest soils, 1%. The soils of the reserve are relatively thin; they have a distinct tonguing of the humus horizon and are often saline and solonetzic. The latter properties are inherited from the parent materials and are preserved in the soils for a long time under the conditions of a dry continental climate. The genetic features of the soils differ in dependence on the composition and age of the parent materials. With respect to the thickness of the soil profiles and the reserves of soil humus, the soils can be arranged into the following lithogenic sequence: the soils developed from the eluvium of igneous rocks-redeposited kaolin clay-montmorillonite-hydromica nonsaline and saline loams and clays. The content of Corg in the upper 20 cm varies from 2.5 to 5.6%, and the reserves of Corg in the layers of 0-0.5 and 0-1.0 m reach 57-265 and 234-375 t/ha, respectively. The soils of pastures subjected to overgrazing occupy two-thirds of the reserve. Their humus content is 10-16% higher in comparison with that in the analogous plowed soils. Another characteristic feature of the humus in the soils of the pastures is its enrichment in the labile fraction (28-40% of Corg).

Prikhod'ko, V. E.; Ivanov, I. V.; Manakhov, D. V.; Manakhova, E. V.

2012-08-01

320

Considerations over the distribution of the organic matter in the soil cover of Transylvania Plain (Romania)  

NASA Astrophysics Data System (ADS)

Considerations over the distribution of the organic matter in the soil cover of Transylvania Plain (Romania) Horea Cacovean*, Titus Man**, Teodor Rusu*** *OSPA-Cluj- 1Faglui street, Cluj Napoca, RO-40048, Romania- turda75@yahoo.com ** Faculty of Geographie, University of Babes-Bolyai, 5-7 Clinicilor street, Cluj Napoca, RO-400006, Romania *** Faculty of Agriculture, USAMV, 3-5 Calea Manastur street,Cluj Napoca, RO-400372, Romania Soil degradation has become a major concern in the Transylvania Plain. Erosion, landslides, salinization, gleysation, and loss of humus are the main forms of soil deterioration in that region. This factsheet deals with the role of organic matter in soil productivity and the effects of various management practices and abandonment of the lands on soil organic matter. Soils in Transylvania Plain are analyzed concerning the amount of humus they contain. The influence of soil texture, climatic variables, and soil management on the qualitative soil humus content was studied in the top 20 cm of different managed loess soils of more then 100 profiles along a climosequence in that region. Taken together, soil, landform, land use and vegetation data suggest: (1) summit positions are relatively stable with immobilizing humus environments; (2) the content of humus increase progressively down steep at the contact with the floodplains; 3) without the influx of organic materials, erodible backslopes may become humus depleted as it happen the poor inputs of grassland and forest litter are mixed with surface soil horizon; 4) influx of mixed sediment and organic materials from backslopes maintains concentrations of humus on footslopes and toeslopes. This influence was more pronounced in the heavy clayey soils, suggesting that the accumulation of humus was enhanced by organo-mineral interactions. Entrenchment of drainage ways can circumvent these translocation processes. The results underscore the importance of functional connectivity between upland hillslopes and alluvial soils.

Cacovean, Horia; Man, Titus; Rusu, Teodor

2010-05-01

321

Cover crops alter phosphorus soil fractions and organic matter accumulation in a Peruvian cacao agroforestry system  

Microsoft Academic Search

In many tropical soils, excessive weathering of primary minerals confounded by intense agricultural production has resulted\\u000a in the depletion of organic matter and plant available forms of phosphorus (P). Long-term growth of cover crops in tropical\\u000a agroforestry systems have been shown to influence nutrient cycling, and soil organic matter pools. The objective of this experiment\\u000a was to assess the affect

Hollie Hall; Yuncong Li; Nicholas Comerford; Enrique Arévalo Gardini; Luis Zuniga Cernades; Virupax Baligar; Hugh Popenoe

2010-01-01

322

Fractions of organic carbon in soils under different crop rotations, cover crops and fertilization practices  

Microsoft Academic Search

We investigated the long-term effects (13–48 years) of crop rotations, cover crops and fertilization practices on soil organic carbon fractions. Two long-term experiments conducted on a clay loam soil in southeastern Norway were used. From the crop rotation experiment, two rotations, one with two years grain + four years grass and the second with grain alone (both for 6 years),

Z. Yang; B. R. Singh; B. K. Sitaula

2004-01-01

323

Soil nitrous oxide emissions in long-term cover crops-based rotations under subtropical climate  

Microsoft Academic Search

It has been shown that cover crops can enhance soil nitrous oxide (N2O) emissions, but the magnitude of increase depends on the quantity and quality of the crop residues. Therefore, this study aimed to evaluate the effect of long-term (19 and 21 years) no-till maize crop rotations including grass [black oat (Avena strigosa Schreb)] and legume cover crops [vetch (Vigna

Juliana Gomes; Cimélio Bayer; Falberni de Souza Costa; Marisa de Cássia Piccolo; Josiléia Acordi Zanatta; Frederico Costa Beber Vieira; Johan Six

2009-01-01

324

Landfill mining: a critical review of two decades of research.  

PubMed

Landfills have historically been seen as the ultimate solution for storing waste at minimum cost. It is now a well-known fact that such deposits have related implications such as long-term methane emissions, local pollution concerns, settling issues and limitations on urban development. Landfill mining has been suggested as a strategy to address such problems, and in principle means the excavation, processing, treatment and/or recycling of deposited materials. This study involves a literature review on landfill mining covering a meta-analysis of the main trends, objectives, topics and findings in 39 research papers published during the period 1988-2008. The results show that, so far, landfill mining has primarily been seen as a way to solve traditional management issues related to landfills such as lack of landfill space and local pollution concerns. Although most initiatives have involved some recovery of deposited resources, mainly cover soil and in some cases waste fuel, recycling efforts have often been largely secondary. Typically, simple soil excavation and screening equipment have therefore been applied, often demonstrating moderate performance in obtaining marketable recyclables. Several worldwide changes and recent research findings indicate the emergence of a new perspective on landfills as reservoirs for resource extraction. Although the potential of this approach appears significant, it is argued that facilitating implementation involves a number of research challenges in terms of technology innovation, clarifying the conditions for realization and developing standardized frameworks for evaluating economic and environmental performance from a systems perspective. In order to address these challenges, a combination of applied and theoretical research is required. PMID:22083108

Krook, Joakim; Svensson, Niclas; Eklund, Mats

2012-03-01

325

Landfill gas generation and migration: Review of current research  

SciTech Connect

With regard to gas migration, a field investigation is examining bidirectional gas movement through landfill cover materials by processes of pressure and diffusional flow. The purpose of the study is to quantify gas loss from the landfill reservoir by natural venting and air influx due to pumping on recovery wells. Two field sites - a humid site with clay cover and a semiarid site with sand cover - have been instrumented to examine vertical gas movement through cover materials. Results from the humid site indicate that concentrations of methane, carbon dioxide, oxygen and nitrogen in soil gas vary seasonally with soil moisture; up to 10E5 g methane m/sup -2/ yr/sup -1/ are vented through the cover materials at the humid site (area of 17 ht); and during prolonged wet weather, pressure gradients of more than 2 kPa may develop between the cover materials and top of refuse, indicating that pressure flow is periodically an important mechanism for gas transport. Addressing landfill gas generation, the goal is to develop simple assay techniques to examined the gas production potential of landfilled refuse. Refuse samples extracted from various depths in a landfill are being leached by three different methods to separate microbial mass and substrate. The leachates are being subjected to Biochemical Methane Production (BMP) assays with periodic qualitative examination of microbial populations using fluorescence microscopy of live cultures and scanning electron microscopy (SEM). Triplicate assays of the leachates that produce insignificant quantities of biogas after 90 days incubation are being amended with sucrose, a nutrient broth, or a bacterial seed. Response of gas production to each of the three amendments was similar across all samples, regardless of the leaching method originally employed, with nutrient addition producing the most stable long-term biogas production with the highest methane content. 23 refs., 6 figs., 3 tabs.

Bogner, J.; Rose, C.; Vogt, M.; Gartman, D.

1987-01-01

326

Effect of Sub-Pixel Variability of Land-Cover on Soil Moisture Retrieval using SAR Data  

Microsoft Academic Search

The soil moisture response to microwave systems from ground surface is mostly influenced by parameters such as: land cover, and vegetation density, soil texture; which make the retrieval process more complex. In this research, we have used a back-propagation neural network to retrieve the surface soil moisture from Synthetic Aperture Radar (SAR) data acquired by RADARSAT-1 satellite. The soil moisture

T. Lakhankar; H. Ghedira; R. Khanbilvardi

2005-01-01

327

Mercury air-borne emissions from 5 municipal solid waste landfills in Guiyang and Wuhan, China  

NASA Astrophysics Data System (ADS)

A detailed study on atmospheric mercury emissions from municipal solid waste (MSW) landfills in China is necessary to understand mercury behavior in this source category, simply because China disposes of bulk MSW by landfilling and a large quantity of mercury enters into landfills. Between 2003 and 2006, mercury airborne emissions through different pathways, as well as mercury speciation in landfill gas (LFG) were measured at 5 MSW landfills in Guiyang and Wuhan, China. The results showed that mercury content in the substrate fundamentally affected the magnitude of mercury emissions, resulting in the highest emission rate (as high as 57 651 ng Hg m-2 h-1) at the working face and in un-covered waste areas, and the lowest measured at soil covers and vegetation areas (less than 20 ng Hg m-2 h-1). Meteorological parameters, especially solar radiation, influenced the diurnal pattern of mercury surface-air emissions. Total gaseous mercury (TGM) in LFG varied from 2.0 to 1406.0 ng m-3, monomethyl mercury (MMHg) and dimethyl mercury (DMHg) in LFG averaged at 1.93 and 9.21 ng m-3, and accounted for 0.51% and 1.79% of the TGM in the LFG, respectively. Total mercury emitted from the five landfills ranged from 17 to 3285 g yr-1, with the highest from the working face, then soil covering, and finally the vent pipes.

Li, Z. G.; Feng, X.; Li, P.; Liang, L.; Tang, S. L.; Wang, S. F.; Fu, X. W.; Qiu, G. L.; Shang, L. H.

2010-01-01

328

Modeling landfill gas production and movement: Principal landfill gases  

Microsoft Academic Search

A landfill gas generation and movement model is presented in this dissertation. The model is based on solution of a Darcy's law formulation of single component fluid flow in porous media in three dimensions, using a finite element technique. The effects of varying gas production rates, material porosities, and landfill covers, liners, and gas extraction wells are incorporated in the

1991-01-01

329

No-Till Corn\\/Soybean Systems Including Winter Cover Crops: Effects on Soil Properties  

Microsoft Academic Search

The use of winter cover crops (WCC) such as hairy vetch (Vicia villosa Roth) and cereal rye (Secale cereale L.), in a corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation provides long-term benefits that are generally overlooked. There is a particular lack of information regarding the effects of WCC on soil physical and chemi- cal properties. The objective of

M. B. Villamil; G. A. Bollero; R. G. Darmody; F. W. Simmons; D. G. Bullock

330

Snow cover dynamics, soil moisture variability and vegetation ecology in high mountain catchments of central Norway  

Microsoft Academic Search

The influence of water balance on vegetation was investigated by measurements of snow cover dynamics and soil moisture variability within small high mountain catchments of central Norway. The challenge of this study is to explain vegetation patterns by means of a functional ecosystem analysis as a basis for regionalization approaches. Results of a process-oriented analysis of factors determining vegetation were

Jörg Löffler

2005-01-01

331

Characterizing soil organic matter quality in arctic soil by cover type and depth  

Microsoft Academic Search

In the past 30 years, the arctic climate has warmed appreciably. Mounting evidence suggests that climate warming is being amplified at the earth's polar regions. A warmer Arctic could lead to the gradual loss of circumpolar permafrost. Northern soils are estimated to contain 25–33% of the world's soil carbon, much of which is frozen in permafrost as poorly decomposed plant

Daniel M. White; D. Sarah Garland; Chien-Lu Ping; Gary Michaelson

2004-01-01

332

OUTER LOOP LANDFILL CASE STUDY  

EPA Science Inventory

This presentation will describe the interim data reaulting from a CRADA between USEPA and Waste Management, Inc. at the outer Loop Landfill Bioreactor research project located in Louisville, KY. Recently updated data will be presented covering landfill solids, gas being collecte...

333

Response of methanotrophs and methane oxidation on ammonium application in landfill soils  

Microsoft Academic Search

To test the dose effect of ammonium (NH4\\u000a +) fertilization on soil methane (CH4) oxidation by methanotrophic communities, batch incubations were conducted at a wide scale of NH4\\u000a + amendments: 0, 100, 250, 500, and 1,000 mg N?kgdry soil\\u000a ?1. Denaturing gradient gel electrophoresis and real-time quantitative PCR analysis were conducted to investigate the correlation\\u000a between the CH4 oxidation capacity and methanotrophic communities.

Na Yang; Fan Lü; Pinjing He; Liming Shao

334

Estimation of municipal solid waste landfill settlement  

Microsoft Academic Search

The municipal solid waste landfill suffers from large postclosure settlement that occurs over an extended period of time. A large differential settlement may impair foundations, utilities, and other associated facilities constructed on top of a landfill. It may also lead to breakage of the geomembrane and damage of the cover system in a modern municipal solid waste landfill. The waste

Hoe I. Ling; Dov Leshchinsky; Yoshiyuki Mohri; Toshinori Kawabata

1998-01-01

335

Landfill mining: Giving garbage a second chance  

SciTech Connect

Some communities face the problems of lack of landfill space and lack of landfill cover dirt. In some cases, existing landfills may be mined to reclaim dirt for use as cover material and to recover space for reuse. Such mining also has the potential of recovering recyclables and incinerator fuels. Machinery to reclaim refuse deposits, and their heterogeneous composted ingredients, was successfully tested at two Florida landfills in June 1987. One of the Florida mining tests, at the Collier County landfill near the city of Naples, had goals of demonstrating an economical mechanical system to separate the depository's ingredients into usable or redisposable components, and to see if the method could enable the county to avoid the expenses associated with permanent closure of a full landfill. This paper describes the history of the Collier County landfill, the equipment and feasibility test, economics, the monitoring of odors, landfill gas, and heavy metals, and results of the test.

Cobb, C.C.; Ruckstuhl, K. (SPM Group, Inc., Preston, MN (USA))

1988-08-01

336

Microorganism and enzyme activities in the soil of landfill sites of Bereg county  

Microsoft Academic Search

Our main purpose was to study the microflora and the enzyme activity in soil of polluted areas, and to identify the factors affecting them. For the assessment, the following indices were identified: Gross (total) contents of heavy metals (HM) and the content of available heavy metals. Results of correlation analysis showed positive correlation (r = 0.74) between cellulase and phosphatase activities in

Judit L. Halász; Ivana Chonka; Márta Dobroné Tóth; Nadya Boyko; Sándor Balázsy

2008-01-01

337

COMPACTED SOIL BARRIERS OF ABANDONED LANDFILL SITES ARE LIKELY TO FAIL IN THE LONG-TERM  

EPA Science Inventory

Buried wastes are isolated from the environment by barriers constructed entirely or in part of compacted soil. he chief concern in barrier design has been to isolate the waste in the short term by preventing movement of water into and through the waste. owever, in the long term a...

338

The soil-air exchange characteristics of total gaseous mercury from a large-scale municipal landfill area  

NASA Astrophysics Data System (ADS)

The cycle of mercury (Hg) from a gigantic landfill area (area ˜2.72 km 2) was investigated by conducting micrometeorological measurements of its exchange rates across soil-air boundary during the spring season of 2000. Based on this field campaign, we attempted to provide various insights into the Hg exchange processes, especially with respect to the decoupling of the mixed signatures of complex source processes. According to our analysis, the cycle of Hg in the study site appeared to be affected significantly by the vent processes; excessive amount of Hg was expected to be released via ventpipes penetrating up to 60 m depths of the deep landfilled waste layer. The influence of these vent source processes was reflected very sensitively by the windrose pattern. The data collected during the non-easterly winds were representing the typical pattern for a strong source area in which upward emission is predominant in both strength and frequency. On the other hand, the data collected from the easterly winds were characterized by excessive deposition of Hg which we suspect is due mostly to the nearest vent located easterly from our measurement spot. The unique characteristics of each data group, divided by windrose pattern, were consistent from apparent difference in: (1) the absolute magnitude of gradient/flux data sets, (2) frequency of exchange for each of two vertical directions, and (3) E/ D (emission/deposition) ratios for most relevant parameters. The analysis of the short-term variability of exchange patterns over a 24-h scale, also exhibited that the patterns for two different conditions were quite contrasting as a function of time. The magnitude of bidirectional fluxes in the present study is significantly high with values of 254±224 ( N=71 emissions out of 79 fluxes quantified during non-easterly winds) and -1164±1276 ng m -2 h -1 ( N=14 depositions out of 16 fluxes during easterly winds), respectively. If the computed emission rate is extrapolated, we estimate that annual emission of Hg from the study area can amount to approximately 6 kg which is comparable with the estimates for other areas around the globe under strong Hg-pollution.

Kim, Ki-Hyun; Kim, Min-Young; Lee, Gangwoong

339

Interaction effects of climate and land use/land cover change on soil organic carbon sequestration.  

PubMed

Historically, Florida soils stored the largest amount of soil organic carbon (SOC) among the conterminous U.S. states (2.26Pg). This region experienced rapid land use/land cover (LULC) shifts and climate change in the past decades. The effects of these changes on SOC sequestration are unknown. The objectives of this study were to 1) investigate the change in SOC stocks in Florida to determine if soils have acted as a net sink or net source for carbon (C) over the past four decades and 2) identify the concomitant effects of LULC, LULC change, and climate on the SOC change. A total of 1080 sites were sampled in the topsoil (0-20cm) between 2008 and 2009 representing the current SOC stocks, 194 of which were selected to collocate with historical sites (n=1251) from the Florida Soil Characterization Database (1965-1996) for direct comparison. Results show that SOC stocks significantly differed among LULC classes - sugarcane and wetland contained the highest SOC, followed by improved pasture, urban, mesic upland forest, rangeland, and pineland while crop, citrus and xeric upland forest remained the lowest. The surface 20cm soils acted as a net sink for C with the median SOC significantly increasing from 2.69 to 3.40kgm(-2) over the past decades. The SOC sequestration rate was LULC dependent and controlled by climate factors interacting with LULC. Higher temperature tended to accelerate SOC accumulation, while higher precipitation reduced the SOC sequestration rate. Land use/land cover change observed over the past four decades also favored the C sequestration in soils due to the increase in the C-rich wetland area by ~140% and decrease in the C-poor agricultural area by ~20%. Soils are likely to provide a substantial soil C sink considering the climate and LULC projections for this region. PMID:25010945

Xiong, Xiong; Grunwald, Sabine; Myers, D Brenton; Ross, C Wade; Harris, Willie G; Comerford, Nicolas B

2014-09-15

340

Spreading Topsoil Encourages Ecological Restoration on Embankments: Soil Fertility, Microbial Activity and Vegetation Cover  

PubMed Central

The construction of linear transport infrastructure has severe effects on ecosystem functions and properties, and the restoration of the associated roadslopes contributes to reduce its impact. This restoration is usually approached from the perspective of plant cover regeneration, ignoring plant-soil interactions and the consequences for plant growth. The addition of a 30 cm layer of topsoil is a common practice in roadslope restoration projects to increase vegetation recovery. However topsoil is a scarce resource. This study assesses the effects of topsoil spreading and its depth (10 to 30 cm) on two surrogates of microbial activity (?-glucosidase and phosphatase enzymes activity and soil respiration), and on plant cover, plant species richness and floristic composition of embankment vegetation. The study also evaluates the differences in selected physic-chemical properties related to soil fertility between topsoil and the original embankment substrate. Topsoil was found to have higher values of organic matter (11%), nitrogen (44%), assimilable phosphorous (50%) and silt content (54%) than the original embankment substrate. The topsoil spreading treatment increased microbial activity, and its application increased ?-glucosidase activity (45%), phosphatase activity (57%) and soil respiration (60%). Depth seemed to affect soil respiration, ?-glucosidase and phosphatase activity. Topsoil application also enhanced the species richness of restored embankments in relation to controls. Nevertheless, the depth of the spread topsoil did not significantly affect the resulting plant cover, species richness or floristic composition, suggesting that both depths could have similar effects on short-term recovery of the vegetation cover. A significant implication of these results is that it permits the application of thinner topsoil layers, with major savings in this scarce resource during the subsequent slope restoration work, but the quality of topsoil relative to the original substrate should be previously assessed on a site by site basis.

Rivera, Desiree; Mejias, Violeta; Jauregui, Berta M.; Lopez-Archilla, Ana Isabel; Peco, Begona

2014-01-01

341

Cover crops and cultivation: Impacts on soil N dynamics and microbiological function in a Mediterranean vineyard agroecosystem  

Microsoft Academic Search

Impacts of cover crops, tillage and abiotic factors on soil nitrogen (N) dynamics, greenhouse gas emissions, and microbiological functions were investigated in a vineyard in California's Mediterranean climate. Treatments had been established in fall 2001 and were composed of two cover crops [Trios 102 (Triticale×Triosecale), (‘Trios’), Merced Rye (Secale cereale), (‘Rye’)] and cultivation (‘Cultivation’). Soils were sampled every 2–3 weeks

Kerri Steenwerth; K. M. Belina

2008-01-01

342

The frost penetration with the modified soil in the landfill bottom liner system  

Microsoft Academic Search

Many researchers have studied on the effect of freeze\\/thaw phenomena mainly on compacted soil samples of small diameter: Most\\u000a of the experiments done so far were applied to study those effects on pavement design in civil engineering. The paper relates\\u000a the freeze\\/thaw studies performed on large scale equipment to better simulate these effects under the existing field conditions\\u000a in a

Jai-Young Lee; Song Lee

2002-01-01

343

The effect of surface cover and soil devastation on infiltration rate in steep forest plantations  

NASA Astrophysics Data System (ADS)

The Japanese cypress (Hinoki; Chamaecyparis obtusa) is a major commercial tree species in Japan, and without thinning of high-density stands, canopy closure prevents development of understory vegetation. Therefore there is a concern for overlandflow and sediment yield due to infiltration rate lowering. We developed a light-weight rainfall simulator based on the design of Meyer and Harmon (1979). A flat fan Veejet 80150 spraying nozzle (Spraying systems Co., USA) is mounted on the manifold at 2.13 m high from the plot surface. The nozzle oscillates so that the spray fan sweeps across the targeting 1 m x 1 m plot. The Veejet 80150 spraying nozzle produces large raindrops larger than 2 mm in diameter, and can simulate the high raindrop kinetic energy of natural throughfall. A targeted rainfall rate is 180 mm/h. About 30 sprinkling experiments have been conducted on 35-degree hillslopes with varying surface cover in 5 locations in Japan. We obtained the minimum infiltration rate of 14 mm/h where the surface cover is very little. The infiltration rates were plotted against the total understory vegetation and dry weight of total surface cover including litter. The infiltration rate increased with the increasing total surface cover, and generally higher regression coefficient was found for the case of the total surface cover. In some cases, high infiltration rates were obtained where surface cover is low. Two possible explanations can be made; 1) surface soil (especially fine particles) has been washed away, where soil is mostly composed of gravel and the percentage of fine fraction is low, or 2) because of long-term soil loss by raindrop detachment, remaining soil looks like "ghanging"h between exposed fine root networks of Japanese cypress, where soil bulk density is significantly lower than other site. Therefore the infiltration rate in the devastated Japanese cypress plantations is not only controlled by loss of surface vegetation by low light condition, but soil devastation through long-term erosion history would also control the infiltration rate and then geomorphic processes.

Onda, Y.; Hiraoka, M.; Kato, H.; Gomi, T.; Miyata, S.; Mizugaki, S.

2008-12-01

344

Methanotroph Diversity in Landfill Soil: Isolation of Novel Type I and Type II Methanotrophs Whose Presence Was Suggested by Culture-Independent 16S Ribosomal DNA Analysis  

PubMed Central

The diversity of the methanotrophic community in mildly acidic landfill cover soil was assessed by three methods: two culture-independent molecular approaches and a traditional culture-based approach. For the first of the molecular studies, two primer pairs specific for the 16S rRNA gene of validly published type I (including the former type X) and type II methanotrophs were identified and tested. These primers were used to amplify directly extracted soil DNA, and the products were used to construct type I and type II clone libraries. The second molecular approach, based on denaturing gradient gel electrophoresis (DGGE), provided profiles of the methanotrophic community members as distinguished by sequence differences in variable region 3 of the 16S ribosomal DNA. For the culturing studies, an extinction-dilution technique was employed to isolate slow-growing but numerically dominant strains. The key variables of the series of enrichment conditions were initial pH (4.8 versus 6.8), air/CH4/CO2 headspace ratio (50:45:5 versus 90:9:1), and concentration of the medium (1× nitrate minimal salts [NMS] versus 0.2× NMS). Screening of the isolates showed that the nutrient-rich 1× NMS selected for type I methanotrophs, while the nutrient-poor 0.2× NMS tended to enrich for type II methanotrophs. Partial sequencing of the 16S rRNA gene from selected clones and isolates revealed some of the same novel sequence types. Phylogenetic analysis of the type I clone library suggested the presence of a new phylotype related to the Methylobacter-Methylomicrobium group, and this was confirmed by isolating two members of this cluster. The type II clone library also suggested the existence of a novel group of related species distinct from the validly published Methylosinus and Methylocystis genera, and two members of this cluster were also successfully cultured. Partial sequencing of the pmoA gene, which codes for the 27-kDa polypeptide of the particulate methane monooxygenase, reaffirmed the phylogenetic placement of the four isolates. Finally, not all of the bands separated by DGGE could be accounted for by the clones and isolates. This polyphasic assessment of community structure demonstrates that much diversity among the obligate methane oxidizers has yet to be formally described.

Wise, Mark G.; McArthur, J Vaun; Shimkets, Lawrence J.

1999-01-01

345

Black oat cover crop management effects on soil temperature and biological properties on a Mollisol in Texas, USA  

Microsoft Academic Search

Management of a black oat (Avena strigosa [Schreb.]) cover crop by mowing method (none, flail mowing, or sickle bar mowing) affected soil micro environmental conditions and soil microbial and chemical properties. Soil temperatures at depths of 0, 5, 10 and 20 cm were highest in flail mowed treatment plots (up to near 45 °C at 5 cm depth), followed by sickle bar mowed

L. M. Zibilske; D. J. Makus

2009-01-01

346

Role of vegetation cover on soil water balance in two Mediterranean areas: semiarid and dry at southeastern of Spain.  

NASA Astrophysics Data System (ADS)

Water is a limited resource in the semiarid areas, which affects both, the population services, the economic growth, like the natural ecosystems stability. In this context, an accurate knowledge of soil water balance and role of the vegetation cover contribute to improve the management of resources water and forest. These studies are increasingly important, if we consider the latest Assessment Reports of the Intergovernmental Panel on Climate Change. In this paper the main objectives were focused on:(1)To determine the soil water balance on two different climatic conditions, semiarid and dry climate and(2) Assess the effect of vegetation (structure and cover) on soil water balance under the studied climatic conditions. For this purpose we used HYDROBAL ecohydrological model, which calculates at a daily resolution the water flows through of the vegetation canopy, estimates daily soil moisture and predicts deep drainage from the unsaturated soil layer into the aquifer. In order to achieve these objectives, we have selected two sites in the south-eastern of Spain, on soils calcareous and different climatic conditions. Ventós site in a semiarid Mediterranean area and Confrides site in a dry Mediterranean area, with 303 and 611 mm of annual precipitation respectively. Both sites, the predominant vegetation are afforestations with Pinus halepensis on dry grasslands with some patches of thorn shrublands and dwarf scrubs; but it show difference on trees density, cover and height of pines.Soil water balance was determined in each site using HYDROBAL ecohydrological model on one hydrological year (October 2012 and September 2013).Model inputs include climatic variables (daily rainfall and temperature), as well as soil and vegetation characteristics (soil field capacity, soil wilting point, initial soil water content and vegetation cover index). Model outputs are interception, net rainfall, runoff, soil water reserves, actual evapotranspiration, direct percolation, and deep percolation (or aquifer recharge). In the last decade, HYDROBAL model has been used successfully in semiarid conditions, to assess the soil water balance on different vegetation cover types, and the effect of different land-use scenarios on water resources and aquifer recharge. Results highlight the role of vegetation cover type and volume of annual rainfall on the soil water balance. Both sites present similar percentage of vegetation cover(>80%), however in Ventós site (semiarid area), a lower pine cover (44%) and lower volume of annual rainfall produced differences in the soil water balance. In Confrides site (dry area), in spite of show the twice of annual rainfall, a higher pine cover (78%) reduced the net precipitation and consequently affected the soil water balance. An understanding the role of vegetation cover on soil water balance is a very useful tool to implement an optimal management of forest and water resources.

Manrique, Àngela; Ruiz, Samantha; Chirino, Esteban; Bellot, Juan

2014-05-01

347

Superfund Site Remediation by Landfilling - Overview of Landfill Design, Operation, Closure and Postclosure Care Issues1  

Microsoft Academic Search

This article discusses the appropriateness of using landfills as part of remediating hazardous chemical and Superfund sites, with particular emphasis on providing for true long- term public health and environmental protection from the wastes and contaminated soils that are placed in the landfills. Onsite landfilling or capping of existing wastes is typically the least expensive approach for gaining some remediation

G. Fred Lee; Anne Jones-Lee

348

Chlorimuron ethyl sorption and desorption kinetics in soils and herbicide-desiccated cover crop residues  

Microsoft Academic Search

Interaction between a herbicide and plant residue on the soil surface in plant residue management systems such as no-tillage or cover crop is of interest in terms of environmental fate of the herbicide. This study was designed to evaluate sorption and desorption of chlorimuron ethyl {ethyl 2-(((((4- chloro-6-methoxy-2-pyrimidinyl)aminolc~bonyll~olsulfonyllbenzoic acid} in herbicide-desiccated rye (Secale cereale L.) and hairy vetch (Vicia villosa

Krishna N. Reddy; Martin A. Locke; Stephen C. Wagner; Robert M. Zablotowicz; Lewis A. Gaston; Reid J. Smeda

1995-01-01

349

Land-cover changes and potential impacts on soil erosion in the Nan watershed, Thailand  

Microsoft Academic Search

The expansion of built environments and agriculture land in the Nan watershed, Thailand, to support the rapid increase of the national population has resulted in deforestation, thus affecting the ecological balance. This deforestation, especially in high mountainous areas, has led to serious environmental degradation. Recent reports reveal an increasing soil-erosion problem in the watershed. This study analyses land-use and land-cover

Chamaporn Paiboonvorachat; Tonny J. Oyana

2011-01-01

350

Assessing the Biometeorology of a Newly Established Reclamation Soil Cover in Fort McMurray, Alberta  

NASA Astrophysics Data System (ADS)

Several experimental watersheds have been established in the Fort McMurray region as part of a risk-based assessment of various reclamation strategies for oil sands mining. This study has been undertaken to specifically evaluate if the most cost-effective reclamation option (minimal soil depth) can retain sufficient moisture to promote plant development and return the area to a functional boreal ecosystem. The eddy covariance technique was used during the second post-reclamation growing season to quantify the exchange of energy and water vapour atop a 25 cm soil cover, situated on a south facing slope. The 2008 growing season was both hotter and wetter than normal, resulting in large seasonal evapotranspiration (ET) values (309 mm from May 10th - Oct 8th). The majority of available energy was partitioned into latent heat, resulting in a mean Bowen ratio of 0.75 and a Priestley-Taylor alpha coefficient approaching unity (mean = 0.87). A low mean daytime (0900 to 1700 hrs) decoupling coefficient (? = 0.31), which decreased bi- weekly with increasing LAI, suggests that ET at this site was predominantly controlled by canopy resistance (rc). A total derivative analysis of the Penman-Monteith equation was used to demonstrate the sensitivity of ET to changes in available radiation (Ra), vapour pressure deficit (D) and rc between months. Results indicate that ET was particularly influenced by rc during the driest month of July when soil moisture became limited and the vegetation became stressed. ET was more sensitive to changes in D prior to leaf-out and during senescence. Although too early to predict whether this soil cover will be successful in sustaining regeneration, this study provides some insight into the unique biometeorology of the initial stages of engineered soil covers. Over time, this may allow for the detection of specific environmental indicators that may preclude the impending success or failure of reclamation efforts.

Goodbrand, S. C.; Carey, S. K.

2009-05-01

351

Effect of winter cover crops on soil nitrogen availability, corn yield, and nitrate leaching.  

PubMed

Biculture of nonlegumes and legumes could serve as cover crops for increasing main crop yield, while reducing NO3 leaching. This study, conducted from 1994 to 1999, determined the effect of monocultured cereal rye (Secale cereale L.), annual ryegrass (Lolium multiflorum), and hairy vetch (Vicia villosa), and bicultured rye/vetch and ryegrass/vetch on N availability in soil, corn (Zea mays L.) yield, and NO3-N leaching in a silt loam soil. The field had been in corn and cover crop rotation since 1987. In addition to the cover crop treatments, there were four N fertilizer rates (0, 67, 134, and 201 kg N ha(-1), referred to as N0, N1, N2, and N3, respectively) applied to corn. The experiment was a randomized split-block design with three replications for each treatment. Lysimeters were installed in 1987 at 0.75 m below the soil surface for leachate collection for the N 0, N 2, and N 3 treatments. The result showed that vetch monoculture had the most influence on soil N availability and corn yield, followed by the bicultures. Rye or ryegrass monoculture had either no effect or an adverse effect on corn yield and soil N availability. Leachate NO3-N concentration was highest where vetch cover crop was planted regardless of N rates, which suggests that N mineralization of vetch N continued well into the fall and winter. Leachate NO3-N concentration increased with increasing N fertilizer rates and exceeded the U.S. Environmental Protection Agency's drinking water standard of 10 mg N l(-1) even at recommended N rate for corn in this region (coastal Pacific Northwest). In comparisons of the average NO3-N concentration during the period of high N leaching, monocultured rye and ryegrass or bicultured rye/vetch and ryegrass/vetch very effectively decreased N leaching in 1998 with dry fall weather. The amount of N available for leaching (determined based on the presidedress nitrate test, the amount of N fertilizer applied, and N uptake) correlated well with average NO3-N during the high N leaching period for vetch cover crop treatment and for the control without the cover crops. The correlation, however, failed for other cover crops largely because of variable effectiveness of the cover crops in reducing NO3 leaching during the 5 years of this study. Further research is needed to determine if relay cover crops planted into standing summer crops is a more appropriate approach than fall seeding in this region to gain sufficient growth of the cover crop by fall. Testing with other main crops that have earlier harvest dates than corn is also needed to further validate the effectiveness of the bicultures to increase soil N availability while protecting the water quality. PMID:12805863

Kuo, S; Huang, B; Bembenek, R

2001-10-25

352

Effect of cover crops and tillage system on symphylan (Symphlya: Scutigerella immaculata, Newport) and Pergamasus quisquiliarum Canestrini (Acari: Mesostigmata) populations, and other soil organisms in agricultural soils  

Microsoft Academic Search

The garden symphylan (Scutigerella immaculata: Newport) is a common myriapod soil pest of vegetable crops in the Pacific Northwest and other regions of the US. Symphylans consume germinating seeds, plant roots, and above-ground plant parts in contact with the soil. Factors regulating symphylan populations in agricultural soil systems are poorly understood, particularly the effects of farming practices such as cover

R. E Peachey; A Moldenke; R. D William; R Berry; E Ingham; Eric Groth

2002-01-01

353

Associations between land cover categories, soil concentrations of arsenic, lead and barium, and population race/ethnicity and socioeconomic status.  

PubMed

The potential of using land cover/use categories as a proxy for soil metal concentrations was examined by measuring associations between Anderson land cover category percentages and soil concentrations of As, Pb, and Ba in ten sampling areas. Land cover category and metal associations with ethnicity and socioeconomic status at the United States Census 2000 block and block group levels also were investigated. Arsenic and Pb were highest in urban locations; Ba was a function of geology. Consistent associations were observed between urban/built up land cover, and Pb and poverty. Land cover can be used as proxy for metal concentrations, although associations are metal-dependent. PMID:24914533

Davis, Harley T; Aelion, C Marjorie; Lawson, Andrew B; Cai, Bo; McDermott, Suzanne

2014-08-15

354

Landfill methane oxidation across climate types in the U.S.  

PubMed

Methane oxidation in landfill covers was determined by stable isotope analyses over 37 seasonal sampling events at 20 landfills with intermediate covers over four years. Values were calculated two ways: by assuming no isotopic fractionation during gas transport, which produces a conservative or minimum estimate, and by assuming limited isotopic fractionation with gas transport producing a higher estimate. Thus bracketed, the best assessment of mean oxidation within the soil covers from chamber captured emitted CH(4) was 37.5 ± 3.5%. The fraction of CH(4) oxidized refers to the fraction of CH(4) delivered to the base of the cover that was oxidized to CO(2) and partitioned to microbial biomass instead of being emitted to the atmosphere as CH(4) expressed as a percentage. Air samples were also collected at the surface of the landfill, and represent CH(4) from soil, from leaking infrastructure, and from cover defects. A similar assessment of this data set yields 36.1 ± 7.2% oxidation. Landfills in five climate types were investigated. The fraction oxidized in arid sites was significantly greater than oxidation in mediterranean sites, or cool and warm continental sites. Sub tropical sites had significantly lower CH(4) oxidation than the other types of sites. This relationship may be explained by the observed inverse relationship between cover loading and fractional CH(4) oxidation. PMID:21133420

Chanton, Jeffrey; Abichou, Tarek; Langford, Claire; Hater, Gary; Green, Roger; Goldsmith, Doug; Swan, Nathan

2011-01-01

355

Mathematical modelling of water and gas transport in layered soil covers for coal ash deposits. Part 3.  

National Technical Information Service (NTIS)

In earlier reports the design of soil covers for deposits of coal ash from energy production was studied with regard to various parameters like: climate, cover slope, length of cover, hydraulic conductivity of tight layer, influence of a weak zone in the ...

M. Lindgren A. Rasmuson

1992-01-01

356

Influence of Snow Cover Duration on Soil Evaporation and Respiration Efflux in Mixed-conifer Ecosystems  

NASA Astrophysics Data System (ADS)

Subalpine mixed-conifer ecosystems are sensitive to a warming climate and are dependent on snowfall, which is expected to decrease under projected climate change. These changes in snowpack are likely to have important consequences for water and carbon cycling in these ecosystems and those downstream in the watersheds. Particularly within the semiarid southwest, such transitions to a drier and warmer environment will directly influence localized water and carbon dynamics and indirectly influence regional-scale levels of water availability and carbon sequestration. Therefore, in this study we monitored soil evaporation and respiration to evaluate how snow accumulation and duration of snow cover affected these effluxes. Our study took place within a mixed-conifer ecosystem within the Santa Catalina Mountains about 10 km north of Tucson, Arizona. Here, three understory time-lapse digital cameras have monitored snow cover within the footprint of an eddy covariance tower for nearly two years. Using these cameras, we identified locations with short and long snow duration. We then placed 6 soil collars (3 in short snow duration; 3 in long snow duration) within the field of view of each camera. Since July 2010, evaporation and soil respiration data have been collected regularly from these collars; soil temperature and soil moisture measurements were also collected. Our primary findings include: (1) evaporation fluxes do not vary drastically between long and short snow season sites, (2) evaporation fluxes for both short and long snow seasons have a strong relationship with soil moisture and a poor relationship with soil temperature, (3) CO2 fluxes vary noticeably between long and short snow season sites throughout the year, with short snow season fluxes typically higher than those of long snow season sites, and (4) CO2 fluxes for short and long snow seasons have a strong relationship with soil temperature and a poor relationship with soil moisture. Our findings suggest that rates of evaporative water loss will not be strongly influenced by changes in length of snow season, but that CO2 fluxes will be significantly influenced by these environmental changes such that we might expect greater carbon losses to the atmosphere.

Nelson, K.; Papuga, S. A.; John, G. P.; Minor, R.; Barron-Gafford, G. A.

2011-12-01

357

Effects of compaction and wetting of laterite cover soil on development and survival of Musca domestica (Diptera: Muscidae) immatures.  

PubMed

Effects of laterite cover soil with different characteristics on survival of buried eggs, third instar larvae, and pupae of Musca domestica (L.) were studied experimentally. Soil treatments were loose dry soil, loose wet soil, compacted dry soil, and compacted wet soil (CWS). Eggs, third instar larvae, and pupae were buried under 30 cm of the different soil treatments and placed under field conditions until adults emerged. Rearing medium was provided for eggs and larvae, and control treatments of all stages were unburied immatures placed on soil surface. Egg and pupal survival to adult were significantly affected by the cover soil treatments, but third instars were more resilient. Wet soil treatments (loose wet soil and CWS) resulted in significantly reduced pupal survival, but increased survival of eggs. However, CWS significantly reduced adult emergence from buried eggs. Though emergence of house flies buried as eggs was significantly reduced, some were able to hatch and emerging first instar larvae developed to pupation. Although cover soil does not completely prevent fly emergence, it did limit development and emergence of buried house flies. PMID:24180104

Abu Tahir, Nurita; Ahmad, Abu Hassan

2013-09-01

358

Use of LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils  

NASA Technical Reports Server (NTRS)

The estimation of the spatially variable surface moisture and heat fluxes of natural, semivegetated landscapes is difficult due to the highly random nature of the vegetation (e.g., plant species, density, and stress) and the soil (e.g., moisture content, and soil hydraulic conductivity). The solution to that problem lies, in part, in the use of satellite remotely sensed data, and in the preparation of those data in terms of the physical properties of the plant and soil. The work was focused on the development and testing of a stochastic geometric canopy-soil reflectance model, which can be applied to the physically-based interpretation of LANDSAT images. The model conceptualizes the landscape as a stochastic surface with bulk plant and soil reflective properties. The model is particularly suited for regional scale investigations where the quantification of the bulk landscape properties, such as fractional vegetation cover, is important on a pixel by pixel basis. A summary of the theoretical analysis and the preliminary testing of the model with actual aerial radiometric data is provided.

Eagleson, Peter S.; Jasinski, Michael F.

1988-01-01

359

Microbial methane oxidation processes and technologies for mitigation of landfill gas emissions.  

PubMed

Landfill gas containing methane is produced by anaerobic degradation of organic waste. Methane is a strong greenhouse gas and landfills are one of the major anthropogenic sources of atmospheric methane. Landfill methane may be oxidized by methanotrophic microorganisms in soils or waste materials utilizing oxygen that diffuses into the cover layer from the atmosphere. The methane oxidation process, which is governed by several environmental factors, can be exploited in engineered systems developed for methane emission mitigation. Mathematical models that account for methane oxidation can be used to predict methane emissions from landfills. Additional research and technology development is needed before methane mitigation technologies utilizing microbial methane oxidation processes can become commercially viable and widely deployed. PMID:19584243

Scheutz, Charlotte; Kjeldsen, Peter; Bogner, Jean E; De Visscher, Alex; Gebert, Julia; Hilger, Helene A; Huber-Humer, Marion; Spokas, Kurt

2009-08-01

360

Gas pressure and concentration gradients at the top of a landfill  

SciTech Connect

Vertical gas pressure and concentration gradients are being investigated at the Mallard North Landfill (DuPage County, Illinois) using nests of probes installed in the top of refuse and at two depths in the clay cover materials. Soil gas pressures and atmospheric pressure are monitored continuously using electronic pressure transducers linked to a microcomputer. Concentrations of methane, carbon dioxide, nitrogen, and oxygen in the soil gas are determined using a field gas chromatograph. Supporting meteorological, soil temperature, and soil moisture data also are obtained. Based on data from the fall of 1985 and the spring, summer, and fall of 1986, soil gas pressures at all depths responded to changes in barometric pressure; however, the type of response varied, depending on soil moisture and temperature. During warm, dry weather, for example, soil gas pressures in the cover and the top of the refuse equilibrate rapidly with barometric pressure, indicating that diffusion is the major mechanism for gas transport at that time (no pressure gradients). The rate of diffusional flow depends on the properties of the cover materials, as well as the concentration gradients. Increases in soil moisture, in particular, decrease the gas-filled porosity of the cover materials and retard gas movement. Our results suggest that design and maintenance of tighter landfill covers should be considered at sites where gas recovery is anticipated, to prevent loss of methane and influx of oxygen.

Bogner, J.; Vogt, M.; Moore, C.; Gartman, D.

1987-01-01

361

Emission characteristics and air-surface exchange of gaseous mercury at the largest active landfill in Asia  

NASA Astrophysics Data System (ADS)

The emission characteristics and air-surface exchange of gaseous elemental mercury (GEM) at Laogang landfill in Shanghai, China, the largest active landfill in Asia, has been investigated during two intensive field campaigns in 2011 and 2012. The mercury (Hg) content in municipal solid waste (MSW) varied widely from 0.19 to 1.68 mg kg-1. Over the closed cell in the landfill, the mean ambient air GEM concentration was virtually indistinguishable from the hemispherical background level (1.5-2.0 ng m-3) while the concentration downwind of ongoing landfill operation (e.g. dumping, burying and compacting of MSW) was clearly elevated. GEM emission through landfill gas (LFG) was identified as a significant source. GEM concentrations in LFGs collected from venting pipes installed in different landfill cells varied widely from 3.0 to 1127.8 ng m-3. The GEM concentrations were found negatively correlated to the age of LFG cells, suggesting GEM released through LFG declined readily with time. The GEM emission from this source alone was estimated to be 1.23-1.73 mg h-1. GEM emission from cover soil surfaces was considerably lower and at a scale comparable to that of background soil surfaces. This is in contrast to earlier reports showing enhanced GEM emissions from landfill surfaces in Southern China, probably due to the difference in soil Hg content and gas permeability characteristics of soils at different sites. Vertical concentration profiles of GEM in the interstitial gas of buried MSW were sampled, perhaps for the first time, which exhibited a wide spatial variability (4.9-713.1 ng m-3) in the 3-year-old landfill cell investigated. GEM emission from landfill operation was estimated to be 290-525 mg h-1 using a box model. This suggests that GEM degassing from Laogang landfill is quantitatively largely dominated by emissions from daily landfilling operations with a much smaller contribution from LFG venting and insignificant (bi-directional fluxes near zero) contribution from surfaces capped with a soil layer. This study reveals divergent GEM emission patterns among landfill cells of different ages, and provides essential emission estimates for formulating Hg emission reduction strategies for a large landfill.

Zhu, Wei; Li, Zhonggen; Chai, Xiaoli; Hao, Yongxia; Lin, Che-Jen; Sommar, Jonas; Feng, Xinbin

2013-11-01

362

Infiltration through layered-soil trench covers: Response to an extended period of rainfall  

USGS Publications Warehouse

Four experimental waste disposal trench covers were constructed to test the effectiveness of layered-soil cover designs in reducing infiltration. Three covers each consisted of a layer of gravel between an overlying wick layer of compacted fine-grained material (either silt or loam) and a compacted loam base; the fourth consisted of compactd silt over a loam base. Capillary pressures were monitored at various depths within each cover during October through December, 1985, a period of high rainfall following a dry summer. Moisture movement in response to the rainfall was rapid within the upper layers of all four test covers, but was retained within the upper layers of the three wick-system trenches, despite variations in the design thickness and composition of the wick layers. In the wick systems, moisture did not enter the gravel until a threshold level of pressure approaching saturation was established in the wick layer. Once this level was reached, moisture moved into and through the gravel. This experiment demonstrates the functionality of field-scale wick systems. ?? 1988.

Larson, T. H.; Keefer, D. A.; Albrecht, K. A.; Cartwright, K.

1988-01-01

363

Soil formation and mass fluxes in cover beds of the Kowarski Grzbiet (eastern Karkonosze Mountains)  

NASA Astrophysics Data System (ADS)

The Karkonosze Mountains are a Hercynian mid-mountain range located in the Central Europe, at the border of Poland and the Czech Republic. Although granite is the dominant geology in the western and middle part of the mountain belt, the eastern part consists mainly of different types of the schists and gneiss. Small mountain glaciers that developed during the late Weichselian, periglacial conditions as well as an intense activity of slope processes during the Atlantic and at the Atlantic/Sub-Boreal transition have shaped the landscape during the Quaternary and formed sequences of cover beds which became the main parent material of soils. In our study we focused on the eastern, metamorphic part that is characterised by mica schist, amphibole schist and gneiss. A transect was studied along the slope of Skalny Stol (1281 m as.l) of the Kowarski Grzbiet having NW exposition. This transect included 5 profiles along a slope section from 1269 m asl to 1142 m asl. In all profiles, at least three layers could be distinguished: (a) a basal layer formed probably in the Younger Dryas with features of solifluction - found in almost every relief position (b) a transition periglacial zone, interpreted as a result of cryoturbation, and (c) a top cover having almost no rock fragments and most likely relatively young (Holocene) appeared in all profiles. However, in some soils, colluvial material was found in the topsoil. Within the stony cover bed, at the flat plateaus and in the upper section of slope Hyperskeletic and Skeletic Podzols have developed (the basal and transition layer contained amphibole schist and the top layer only mica schist). In the middle and lower slope position where gelisolifluction layers were detected, colluvial material was superimposed and as a consequence Cambisols and Stagnosols have developed. Consequently, the soil distribution pattern in this landscape is strongly affected by the arrangement of the slope deposits. Sediments having a different age and origin should reflect different weathering mechanisms and clay minerals formation and transformation processes. To check this hypothesis we: (i) identified clay minerals using qualitative and semi-quantitative methods, (ii) measured total element content in fine earth using X-ray fluorescence, (iii) calculated weathering indexes such as the (K+Ca)/Ti ratio, indexes A and B and (iv) measured erosion rates using 10Be in soils. These measurements confirmed the complex soil formation characteristics of the soils and demonstrated the highly dynamic system of slope deposits (in terms of matter fluxes).

Waroszewski, Jaroslaw; Egli, Markus; Brandová, Dagmar; Plötze, Michael; Kabala, Cezary; Kierczak, Jakub

2014-05-01

364

Land-cover effects on soil organic carbon stocks in a European city.  

PubMed

Soil is the vital foundation of terrestrial ecosystems storing water, nutrients, and almost three-quarters of the organic carbon stocks of the Earth's biomes. Soil organic carbon (SOC) stocks vary with land-cover and land-use change, with significant losses occurring through disturbance and cultivation. Although urbanisation is a growing contributor to land-use change globally, the effects of urban land-cover types on SOC stocks have not been studied for densely built cities. Additionally, there is a need to resolve the direction and extent to which greenspace management such as tree planting impacts on SOC concentrations. Here, we analyse the effect of land-cover (herbaceous, shrub or tree cover), on SOC stocks in domestic gardens and non-domestic greenspaces across a typical mid-sized U.K. city (Leicester, 73 km(2), 56% greenspace), and map citywide distribution of this ecosystem service. SOC was measured in topsoil and compared to surrounding extra-urban agricultural land. Average SOC storage in the city's greenspace was 9.9 kg m(-2), to 21 cm depth. SOC concentrations under trees and shrubs in domestic gardens were greater than all other land-covers, with total median storage of 13.5 kg m(-2) to 21 cm depth, more than 3 kg m(-2) greater than any other land-cover class in domestic and non-domestic greenspace and 5 kg m(-2) greater than in arable land. Land-cover did not significantly affect SOC concentrations in non-domestic greenspace, but values beneath trees were higher than under both pasture and arable land, whereas concentrations under shrub and herbaceous land-covers were only higher than arable fields. We conclude that although differences in greenspace management affect SOC stocks, trees only marginally increase these stocks in non-domestic greenspaces, but may enhance them in domestic gardens, and greenspace topsoils hold substantial SOC stores that require protection from further expansion of artificial surfaces e.g. patios and driveways. PMID:24309424

Edmondson, Jill L; Davies, Zoe G; McCormack, Sarah A; Gaston, Kevin J; Leake, Jonathan R

2014-02-15

365

Impact of urban cover fraction on SMOS and SMAP surface soil moisture retrieval  

NASA Astrophysics Data System (ADS)

L-band (~1.4 GHz) microwave radiometry has been widely acknowledged as the most promising technique for surface (top ~5cm) soil moisture observation at regional and global scales, due to its all weather capability, direct relationship to soil moisture, and reduced sensitivity to surface roughness and vegetation. Radiometer observations of microwave emission from the soil surface are used to estimate soil moisture through a radiative transfer model using ancillary information including land cover and soil properties etc. This technique has been applied to the ESA's (European Space Agency) Soil Moisture and Ocean Salinity (SMOS) satellite, the first soil moisture dedicated space mission, launched on 2nd Nov. 2009. Similarly, radiometer techniques will be employed by NASA's (National Aeronautics and Space Administration) Soil Moisture Active and Passive (SMAP) mission, in both the passive and active-passive products. However, passive microwave soil moisture retrieval suffers from land surface heterogeneity at coarse scales; with the radiometer footprints of both missions being ~40 km, which is the best spatial resolution currently achievable using current satellite antenna technology. In order to achieve the ~0.04 m3/m3 target volumetric soil moisture accuracies at such scales, microwave contributions of non-soil targets (such as urban areas) within the sensors' field-of-view needs to be considered in the retrieval algorithm error budget and implementation, since the impact could potentially be significant if ignored. Currently there is a lack of knowledge on the microwave behaviour of non-soil targets, with little assessment of their microwave emissions and impact on satellite scale footprints. Therefore, the objectives of this study are to 1) investigate the relationship between urban induced brightness temperature uncertainties and urban fraction, 2) extract urban fraction thresholds for negligible brightness temperature impact by urban areas based on the SMOS and SMAP error budgets, and 3) use these thresholds to identify SMOS and SMAP pixels with likely non-negligible urban impacts world-wide. In this work, airborne datasets from three field campaigns in the Murrumbidgee catchment, in southeast of Australia, were used: i) the NAFE'06 (National Airborne Field Experiment in 2006), ii) the AACES-1 (Australian Airborne Cal/val Experiment for SMOS), and iii) the AACES-2. During these campaigns, brightness temperature observations were made at 1-km resolution across 20 independent SMOS/SMAP sized footprints of which a number contain urban areas of different size. The NSW (New South Wales, Australia) Land use map with 50 m resolution was used to distinguish brightness temperature observations of the urban area and surrounding natural land surface, from which urban fraction thresholds for SMOS and SMAP were derived. These thresholds were then applied globally based on an urban fraction map calculated using the MODIS Urban Land Cover 500-m product.

Ye, N.; Walker, J. P.; Rudiger, C.; Ryu, D.; Gurney, R.

2011-12-01

366

Effects of silica fume on the geotechnical properties of fine-grained soils exposed to freeze and thaw  

Microsoft Academic Search

Both the landfill liner and cover systems are the most important parts on a waste disposal landfill site. These systems are generally constructed using compacted fine-grained soils. It is known that the strength and permeability are particularly affected by freezing and thawing cycles in the cold regions. The aim of this study is to reduce the effects of freezing and

Ekrem Kalkan

2009-01-01

367

Nitrate-nitrogen, land use/land cover, and soil drainage associations at multiple spatial scales.  

PubMed

Managing non-point-source pollution of water requires knowledge of land use/land cover (LULC) influences at altering watershed scales. To gain improved understanding of relationships among LULC, soil drainage, and dissolved nitrate-N dynamics within the Calapooia River Basin in western Oregon, we selected 44 watersheds ranging in size between 3 and 33 km(2) for monthly synoptic sampling of surface water quality between October 2003 and September 2004. Seasonal associations were examined between dissolved nitrate-N and proportion of woody vegetation or poorly drained soils at differing scales (10, 20, 30, 60, 90, 150, 300 m, and entire watershed), which we defined as influence zones (IZs), surrounding stream networks. Correlations between nitrate-N and proportion woody vegetation or poorly drained soil at each IZ were analyzed for differences using the Hotelling-Williams test. We observed negative correlations (r = -0.81 to -0.94) between nitrate-N and proportion of woody vegetation during winter and spring. Poorly drained soils had positive correlations (r = 0.63-0.87) with nitrate-N. Altering the scale of analysis significantly changed correlations between nitrate-N and woody vegetation, with IZs <150 m being stronger than the watershed scale during winter. However, absolute differences in correlation values were small, indicating minimal ecological consequence for significant differences among scales. In contrast, nitrate-N correlations with poorly drained soil were stronger at the watershed scale than the 10- through 90-m IZs during winter and spring, and absolute differences were sufficient to suggest that scale is ecologically important when determining associations between dissolved nitrate-N and poorly drained soils. PMID:19465723

Floyd, William C; Schoenholtz, Stephen H; Griffith, Stephen M; Wigington, Parker J; Steiner, Jeffrey J

2009-01-01

368

Biogenic NO emission from a spruce forest soil in the Fichtelgebirge (Germany) under the influence of different understorey vegetation cover  

NASA Astrophysics Data System (ADS)

Within the framework of the EGER project (ExchanGE processes in mountainous Regions) soil samples have been taken from the spruce forest site "Weidenbrunnen" (Fichtelgebirge, Germany) in September 2008 to determine the NO exchange in the laboratory and for a series of soil analyses. The soil was sampled below different understorey vegetation covers: young Norway spruce, moss/litter, blueberries and grass. We investigated the net NO release rate from corresponding organic layers as well as from the A horizon of respective soils. Additionally we measured pH, C/N ratio, contents of ammonium, nitrate, and organic C, bulk density, the thickness of the organic layer and the quality of the organic matter. Net NO release rates (as well as the NO production and NO consumption rates) from the soil samples were determined by a fully automated laboratory incubation & fumigation system. Purified dry air passed five dynamic incubation chambers, four containing water saturated soil samples and one reference chamber. By this procedure, the soil samples dried out slowly (within 2-6 days), covering the full range of soil moisture (0-300% gravimetric soil moisture). To quantify NO production and NO consumption rates separately, soil samples were fumigated with zero-air (approx. 0 ppb NO) and air of 133 ppb NO. The chambers were placed in a thermostatted cabinet for incubation at 10 an 20Ë? C. NO and H2O concentrations at the outlet of the five dynamic chambers were measured sequentially by chemiluminescence and IR-absorption based analyzers, switching corresponding valves every two minutes. Net NO release rates were determined from the NO concentration difference between soil containing and reference chambers. Corresponding measurements of H2O mixing ratio yielded the evaporation loss of the soil samples, which (referenced to the gravimetric soil water content before and after the incubation experiment) provided the individual soil moisture contents of each soil samples during the incubation experiment. Our contribution focus net NO release rates, NO production and NO consumption rates of spruce forest soils sampled under different understorey vegetation covers. Generally, organic layers show significant higher NO production and NO consumption rates than the soils from the corresponding A horizons. Soils under the understorey vegetation cover "moos/litter" revealed the lowest NO production and NO consumption rates. Net NO release rates, NO production and NO consumption rates of soil samples obtained below the four different under- storey vegetation covers will be discussed in terms of pH, C/N ratio, contents of ammonium, nitrate, and organic C, bulk density, thickness of organic layer, as well as quality of the organic matter.

Bargsten, A.; Andreae, M. O.; Meixner, F. X.

2009-04-01

369

The influence of atmospheric pressure on landfill methane emissions  

SciTech Connect

Landfills are the largest source of anthropogenic methane (CH{sub 4}) emissions to the atmosphere in the United States. However, few measurements of whole landfill CH{sub 4} emissions have been reported. Here, we present the results of a multi-season study of whole landfill CH{sub 4} emissions using atmospheric tracer methods at the Nashua, New Hampshire Municipal landfill in the northeastern United States. The measurement data include 12 individual emission tests, each test consisting of 5-8 plume measurements. Measured emissions were negatively correlated with surface atmospheric pressure and ranged from 7.3 to 26.5 m{sup 3} CH{sub 4} min{sup -1}. A simple regression model of our results was used to calculate an annual emission rate of 8.4x10{sup 6} m{sup 3} CH{sub 4} year{sup -1}. These data, along with CH{sub 4} oxidation estimates based on emitted landfill gas isotopic characteristics and gas collection data, were used to estimate annual CH{sub 4} generation at this landfill. A reported gas collection rate of 7.1x10{sup 6} m{sup 3} CH{sub 4} year{sup -1} and an estimated annual rate of CH{sub 4} oxidation by cover soils of 1.2x10{sup 6} m{sup 3} CH{sub 4} year{sup -1} resulted in a calculated annual CH{sub 4} generation rate of 16.7x10{sup 6} m{sup 3} CH{sub 4} year{sup -1}. These results underscore the necessity of understanding a landfill's dynamic environment before assessing long-term emissions potential.

Czepiel, P.M.; Shorter, J.H.; Mosher, B.; Allwine, E.; McManus, J.B.; Harriss, R.C.; Kolb, C.E.; Lamb, B.K

2003-07-01

370

The applicability of ERTS-1 data covering the major landforms of Kenya. [landforms, vegetation, soils, forests  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Five investigators report on the applicability of ERTS-1 data covering the major landforms of Kenya. Deficiencies due to lack of equipment, repetitive coverage and interpretation know-how are also reported on. Revision of lake shorelines is an immediate benefit. Basement system metasediments are rapidly differentiated, but dune areas are not readily distinguishable from sandy soils. Forest, moorland, high altitude grass, tea, and conifer plantations are readily distinguished, with podocarpus forest especially distinguishable from podocarpus/juniperus forest. In the arid areas physiographic features, indicating the major soil types, are readily identified and mapped. Preliminary vegetation type analysis in the Mara Game Reserve indicates that in a typical savannah area about 36% of the vegetation types are distinguishable at a scale of 1:1 million as well as drainage patterns and terrain features.

Omino, J. H. O. (principal investigator)

1973-01-01

371

Short-term cover crop decomposition in organic and conventional soils: Soil microbial and nutrient cycling indicator variables associated with different levels of soil suppressiveness to Pythium aphanidermatum  

Microsoft Academic Search

Stages of oat-vetch cover crop decomposition were characterized over\\u000a time in terms of carbon and nitrogen cycling, microbial activity and\\u000a community dynamics in organically and conventionally managed soils in a\\u000a field experiment and a laboratory incubation experiment. We subsequently\\u000a determined which variables describing soil microbial community dynamics,\\u000a C and N cycling could be used as predictors of Pythium aphanidermatum\\u000a damping-off

N. J. Grünwald; S. Hu; A. H. C. van Bruggen

2000-01-01

372

Use of LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils  

NASA Technical Reports Server (NTRS)

This work focuses on the characterization of natural, spatially variable, semivegetated landscapes using a linear, stochastic, canopy-soil reflectance model. A first application of the model was the investigation of the effects of subpixel and regional variability of scenes on the shape and structure of red-infrared scattergrams. Additionally, the model was used to investigate the inverse problem, the estimation of subpixel vegetation cover, given only the scattergrams of simulated satellite scale multispectral scenes. The major aspects of that work, including recent field investigations, are summarized.

Eagleson, Peter S.; Jasinski, Michael F.

1988-01-01

373

Cover crops influence soil properties and tree performance in an organic apple ( Malus domestica Borkh) orchard in northern Patagonia  

Microsoft Academic Search

Little is known about the effects of cover crops on soil properties in organic orchards. To fill this gap, this work aimed\\u000a at examining the effects of several cover crops on soil fertility, nitrate dynamics, populations of nematodes and tree performance\\u000a in an organic orchard of apple cv. Royal Gala\\/EM 26 planted in 1994 at 4 × 2 m. In 1999 the following

E. E. Sánchez; A. Giayetto; L. Cichón; D. Fernández; M. C. Aruani; M. Curetti

2007-01-01

374

Landfill Gas Generation and Migration: Review of Current Research.  

National Technical Information Service (NTIS)

With regard to gas migration, a field investigation is examining bidirectional gas movement through landfill cover materials by processes of pressure and diffusional flow. The purpose of the study is to quantify gas loss from the landfill reservoir by nat...

J. Bogner C. Rose M. Vogt D. Gartman

1987-01-01

375

Factors affecting temporal H2S emission at construction and demolition (C&D) debris landfills.  

PubMed

Odor problems associated with H2S emissions often result in odor complaints from nearby residents of C&D debris landfills, especially in the early morning. As part of a field study conducted on H2S removal ability using different cover materials, daily and seasonal H2S emissions through a soil cover layer were monitored at a C&D debris landfill to investigate factors affecting H2S emissions. H2S emission rates were not a constant, but varied seasonally, with an average emission rate of 4.67×10(-6)mgm(-2)s(-1). During a the 10-month field study, as the H2S concentration increased from 140ppm to about 3500ppm underneath the cover soil in the testing cell, H2S emissions ranged from zero to a maximum emission rate of 1.24×10(-5)mgm(-2)s(-1). Continuous emission monitoring indicated that H2S emissions even changed over time throughout the day, generally increasing from morning to afternoon, and were affected by soil moisture and temperature. Laboratory experiments were also conducted to investigate the effects of H2S concentration and cover soil moisture content on H2S emissions. The results showed that increased soil moisture reduced H2S emissions by retarding H2S migration through cover soil and dissolving H2S into soil water. The field study also indicated that due to atmospheric dispersion, high H2S emissions may not cause odor problems. PMID:23968554

Xu, Qiyong; Townsend, Timothy

2014-02-01

376

Environmental impact assessment on the construction and operation of municipal solid waste sanitary landfills in developing countries: China case study.  

PubMed

An inventory of material and energy consumption during the construction and operation (C&O) of a typical sanitary landfill site in China was calculated based on Chinese industrial standards for landfill management and design reports. The environmental impacts of landfill C&O were evaluated through life cycle assessment (LCA). The amounts of materials and energy used during this type of undertaking in China are comparable to those in developed countries, except that the consumption of concrete and asphalt is significantly higher in China. A comparison of the normalized impact potential between landfill C&O and the total landfilling technology implies that the contribution of C&O to overall landfill emissions is not negligible. The non-toxic impacts induced by C&O can be attributed mainly to the consumption of diesel used for daily operation, while the toxic impacts are primarily due to the use of mineral materials. To test the influences of different landfill C&O approaches on environmental impacts, six baseline alternatives were assessed through sensitivity analysis. If geomembranes and geonets were utilized to replace daily and intermediate soil covers and gravel drainage systems, respectively, the environmental burdens of C&O could be mitigated by between 2% and 27%. During the LCA of landfill C&O, the research scope or system boundary has to be declared when referring to material consumption values taken from the literature; for example, the misapplication of data could lead to an underestimation of diesel consumption by 60-80%. PMID:24656422

Yang, Na; Damgaard, Anders; Lü, Fan; Shao, Li-Ming; Brogaard, Line Kai-Sørensen; He, Pin-Jing

2014-05-01

377

Response of tomato plants to simulated landfill gas mixtures  

SciTech Connect

The roots of tomato plants were fumigated with simulated refuse-generated gas mixtures at levels of methane (CH/sub 4/), carbon dioxide (CO/sub 2/), and oxygen (O/sub 2/) previously measured in the atmospheres of landfill cover soils associated with poor growth or death of plants. A concentration of 18% CO/sub 2/ or greater, exceeded in almost 30% of thirty-two landfills examined throughout the US, caused reduced growth and visible symptoms on tomato after 1 wk, regardless of O/sub 2/ level. Doubling the CO/sub 2/ level to that encountered in a typical local site (Edgeboro Landfill) resulted in more severe symptom development and the subsequent death of plants. Methane, in concentrations of 20% and above, found in more than 25% of the landfills visited, while not observed to be toxic per se; was associated with drastic O/sub 2/ depletion in the soil atmosphere, which activity was believed to be the cause of the plant decline.

Arthur, J.J.; Leone, I.A.; Flower, F.B.

1985-01-01

378

Carbon mineralization in the soils under different cover crops and residue management in an intensive protected vegetable cultivation  

Microsoft Academic Search

Continuous cropping under plastic greenhouses, a common practice in intensive Chinese vegetable production systems, has led to the decline of soil productivity and crop yields. A 4-year greenhouse experiment on cucumber double-cropping systems was conducted in Changping country, Beijing, China, to investigate the effects of summer cover crops and residue management on soil microbial biomass carbon (MBC), C mineralization and

Yongqiang Tian; Juan Liu; Xuhui Wang; Lihong Gao

2011-01-01

379

Legume cover cropping effects on early growth and soil nitrogen supply in eucalypt plantations in south-western India  

Microsoft Academic Search

Growth and soil N supply in young Eucalyptus tereticornis stands at two sites in Kerala, India, were examined in response to cover cropping with three legume species ( Pueraria phaseoloides, Stylosanthes hamata, and Mucuna bracteata). The effects of legume residues on soil N supply were investigated in a long-term (392 day) laboratory incubation using leaching micro-lysimeters. Residues from the eucalypt and

D. S. Mendham; S. Kumaraswamy; M. Balasundaran; K. V. Sankaran; M. Corbeels; T. S. Grove; A. M. O’Connell; S. J. Rance

2004-01-01

380

Electromagnetic wave scattering from vegetation (Potato) and vegetation covered soil moisture for remote sensing  

NASA Astrophysics Data System (ADS)

In the country with limited resources, where the nutrition level of the population has to be maintained under inhospitable situation, the potato has a special value as food. Therefore efforts should be made for improvement and spreading the cultivation of this important crop. It demands an effective program that may provide information about potato growing areas and the growth conditions. Remote sensing has been acknowledged to be a valuable source of spatially comprehensive and temporally repeatable information of crop covered soil moisture, crop growth climatic information etc, which is useful and necessary for agriculture purposes. For this purpose, microwave remote sensing has evolved as an important tool. Since microwave are able to penetrate more deeply into vegetation and underneath ground surface. It is also preferred to the optical frequency band because microwave can work in all type of weather and have a wide signal dynamic range compared optical wavelengths. However interpretation of microwave scattering from agricultural crops requires an understanding the interaction among microwave, vegetative material and the soil. In order to develop useful forward and inverse models for retrieving the vegetation characteristic, it is necessary to know in detail the dielectric properties and plant structure of the vegetation over the range of expected growing conditions. In this paper, a theoretical model based on microwave interaction with potato crop along with examination of biomass of potato crop with the varying underlying soil moisture is studied. For this purpose, X-band (9.5GHz) scatterometer is used for studying the interaction of microwave with potato crop biomass and underlying soil moisture at various sensor parameters (i.e. angular variation and polarization, HH- and VV-). Although there may be a lot of crop parameters (i.e. crop height, leaf area index, etc) which also gives their effect on microwave. All this parameters are interlinked in the crop. So, this study is focused on biomass, which is one of the main parameter of crop and related with dielectric. Scattering coefficient at X-band showed strong sensitivity to different growth cycle of potato. The soil effect on scattering coefficient was prominent at steeper incidence angle (less than 40 degree) where as potato plant effects are more dominant at higher incidence angle (more than 40 degree). The microwave response of potato is polarization dependent and is more prominent for VV-Pol than HH-Pol at every stages of growth of potato and this strong polarization dependence can play a strong role for crop discrimination. The dependency of scattering coefficient on biomass is statistically checked by the linear regression analysis and results of regression analysis confirm the experimental results i.e., scattering coefficient increases as the biomass increases in the potato crop. The best angle to observe and retrieve the biomass by scattering coefficient is 55 degree and 60 degree incidence angles for HH-Pol and VV-Pol respectively. The regression results also revealed that scattering coefficient is positively correlated with soil moisture for both like pols. This result follows many earlier findings. The best incidence angle to compute the potato covered soil moisture from scattering coefficient is 35 degree and 30 degree for HH- and VV-Pol respectively. The HH- pol has edge over VV-pol for observing the potato the covered soil moisture. This approach provides a new direction to understand the potato scattering at X-band for remote sensing.

Singh, Keshev

381

Feasibility of using LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils  

NASA Technical Reports Server (NTRS)

Research activities conducted from February 1, 1985 to July 31, 1985 and preliminary conclusions regarding research objectives are summarized. The objective is to determine the feasibility of using LANDSAT data to estimate effective hydraulic properties of soils. The general approach is to apply the climatic-climax hypothesis (Ealgeson, 1982) to natural water-limited vegetation systems using canopy cover estimated from LANDSAT data. Natural water-limited systems typically consist of inhomogeneous vegetation canopies interspersed with bare soils. The ground resolution associated with one pixel from LANDSAT MSS (or TM) data is generally greater than the scale of the plant canopy or canopy clusters. Thus a method for resolving percent canopy cover at a subpixel level must be established before the Eagleson hypothesis can be tested. Two formulations are proposed which extend existing methods of analyzing mixed pixels to naturally vegetated landscapes. The first method involves use of the normalized vegetation index. The second approach is a physical model based on radiative transfer principles. Both methods are to be analyzed for their feasibility on selected sites.

Eagleson, P. S.

1985-01-01

382

Partial least-squares regression for linking land-cover patterns to soil erosion and sediment yield in watersheds  

NASA Astrophysics Data System (ADS)

There are strong ties between land cover patterns and soil erosion and sediment yield in watersheds. The spatial configuration of land cover has recently become an important aspect of the study of geomorphological processes related to erosion within watersheds. Many studies have used multivariate regression techniques to explore the response of soil erosion and sediment yield to land cover patterns in watersheds. However, many landscape metrics are highly correlated and may result in redundancy, which violates the assumptions of a traditional least-squares approach, thus leading to singular solutions or otherwise biased parameter estimates and confidence intervals. Here, we investigated the landscape patterns within watersheds in the Upper Du River watershed (8973 km2) in China and examined how the spatial patterns of land cover are related to the soil erosion and sediment yield of watersheds using hydrological modeling and partial least-squares regression (PLSR). The results indicate that the watershed soil erosion and sediment yield are closely associated with the land cover patterns. At the landscape level, landscape characteristics, such as Shannon's diversity index (SHDI), aggregation index (AI), largest patch index (LPI), contagion (CONTAG), and patch cohesion index (COHESION), were identified as the primary metrics controlling the watershed soil erosion and sediment yield. The landscape characteristics in watersheds could account for as much as 65% and 74% of the variation in soil erosion and sediment yield, respectively. Greater interspersion and an increased number of patch land cover types may significantly accelerate soil erosion and increase sediment export. PLSR can be used to simply determine the relationships between land-cover patterns and watershed soil erosion and sediment yield, providing quantitative information to allow decision makers to make better choices regarding landscape planning. With readily available remote sensing data and rapid developments in geographic information system (GIS) technology, this practical and simple PLSR approach could be applied to a variety of other watersheds.

Shi, Z. H.; Ai, L.; Li, X.; Huang, X. D.; Wu, G. L.; Liao, W.

2013-08-01

383

Species-diversified plant cover enhances orchard ecosystem resistance to climatic stress and soil erosion in subtropical hillside*  

PubMed Central

Naturally occurring plants in agroecosystem evidently play an important role in ecosystem stability. Field studies on the ecological effects of native plants conserved in orchard and their resistance to adverse climatic stress, and soil erosion were conducted from 1998 to 2001 in a newly developed Changshan-huyou (Citrus changshan-huyou Y.B. Chang) orchard. The experimental area covered 150 ha in typical red soil hilly region in southeastern China. The experimental design was a randomized complete block with six combinations of twelve plant species with four replications. All species used were native in the orchard. Plots were 15×8 m2 and separated by 2 m buffer strips. Precipitation, soil erosion in rainstorm days and aboveground biomass of plant community when rainstorm days ended, soil temperature and moisture under various plant covers during seasonal megathermal drought period, antiscourability of soil with different root density under various simulated rainfalls were measured. Plant cover significantly decreased the daily highest and mean soil temperature and its daily variation in hot-drought season, but there was no significant difference of the alleviation among various plant covers. Plant covers significantly increased the soil moisture in seasonal megathermal drought period. Better moisture maintenance and soil erosion reduction was found when the plant species numbers in cover plant communities increased from one to eight. Higher root density in plant communities with higher species richness increased significantly the antiscourability of the soil. It was suggested that conserving plant communities with diversified native species could produce the best positive ecological effects on citrus orchard ecosystem stability.

Chen, Xin; Yang, Yi-song; Tang, Jian-jun

2004-01-01

384

Cover crop nitrogen availability to conventional and no?till corn: Soil mineral nitrogen, corn nitrogen status, and corn yield  

Microsoft Academic Search

Understanding seasonal soil nitrogen (N) availability patterns is necessary to assess corn (Zea mays L.) N needs following winter cover cropping. Therefore, a field study was initiated to track N availability for corn in conventional and no?till systems and to determine the accuracy of several methods for assessing and predicting N availability for corn grown in cover crop systems. The

Jeffrey D. Vaughan; Greg D. Hoyt; Arthur G. Wollum II

2000-01-01

385

Effect of cover crop on soil physical and chemical properties of an alfisol in the Sudan savannah of Burkina faso  

Microsoft Academic Search

The effect of several leguminous and graminaceous cover crops on soil physical and chemical properties was studied on a moderately eroded Alfisol in the Sudan savannah of Burkina Faso during the growing seasons of 1986 and 1987. Cover crops sown in 1986 were Macroptilium artropurpureum, M. lathyroides, Vigna radiata var. radiata, Cajanus cajan, Alysicarpus vaginalis, Lablab purpureus, Psophocarpus palustris, Digitaria

N. R. Hulugalle

1988-01-01

386

Influence of Cover Crops and Inorganic Nitrogen Fertilization on Tomato and Snap Bean Production and Soil Nitrate Distribution  

Microsoft Academic Search

Commercial vegetable production depends almost solely on inorganic fertilizers. In an era of environmental sensitivity, enrichment of soils with green manures and cover crops may reduce the dependence on these fertilizers while maintaining and enhancing crop yields. The objectives of this research were to determine (1) if supplemental nitrogen (N) at 60 or 120 kg · ha following winter cover

Robert J. Dufault; Dennis R. Decoteau; J. Thomas Garrett; K. Dean Batal; Darbie Granberry; Jeanine M. Davis; Greg Hoyt; Douglas Sanders

2000-01-01