Science.gov

Sample records for active soil gas

  1. Influence of altered precipitation pattern on greenhouse gas emissions and soil enzyme activities in Pannonian soils

    NASA Astrophysics Data System (ADS)

    Forstner, Stefan Johannes; Michel, Kerstin; Berthold, Helene; Baumgarten, Andreas; Wanek, Wolfgang; Zechmeister-Boltenstern, Sophie; Kitzler, Barbara

    2013-04-01

    Precipitation patterns are likely to be altered due to climate change. Recent models predict a reduction of mean precipitation during summer accompanied by a change in short-term precipitation variability for central Europe. Correspondingly, the risk for summer drought is likely to increase. This may especially be valid for regions which already have the potential for rare, but strong precipitation events like eastern Austria. Given that these projections hold true, soils in this area will receive water irregularly in few, heavy rainfall events and be subjected to long-lasting dry periods in between. This pattern of drying/rewetting can alter soil greenhouse gas fluxes, creating a potential feedback mechanism for climate change. Microorganisms are the key players in most soil carbon (C) and nitrogen (N) transformation processes including greenhouse gas exchange. A conceptual model proposed by Schimel and colleagues (2007) links microbial stress-response physiology to ecosystem-scale biogeochemical processes: In order to cope with decreasing soil water potential, microbes modify resource allocation patterns from growth to survival. However, it remains unclear how microbial resource acquisition via extracellular enzymes and microbial-controlled greenhouse gas fluxes respond to water stress induced by soil drying/rewetting. We designed a laboratory experiment to test for effects of multiple drying/rewetting cycles on soil greenhouse gas fluxes (CO2, CH4, N2O, NO), microbial biomass and extracellular enzyme activity. Three soils representing the main soil types of eastern Austria were collected in June 2012 at the Lysimeter Research Station of the Austrian Agency for Health and Food Safety (AGES) in Vienna. Soils were sieved to 2mm, filled in steel cylinders and equilibrated for one week at 50% water holding capacity (WHC) for each soil. Then soils were separated into two groups: One group received water several times per week (C=control), the other group received

  2. Carbon Flux and Isotopic Character of Soil and Soil Gas in Stabilized and Active Thaw Slumps in Northwest Alaska

    NASA Astrophysics Data System (ADS)

    Jensen, A.; Crosby, B. T.; Mora, C. I.; Lohse, K. A.

    2012-12-01

    Permafrost soils store nearly half the world's global carbon. Warming of arctic landscape results in permafrost thaw which causes ground subsidence or thermokarst. On hillslopes, these features rapidly and dramatically alter soil structure, temperature, and moisture, as well as the content and quality of soil organic matter. These changes alter both the rate and mechanism of carbon cycling in permafrost soils, making frozen soils available to both anaerobic and aerobic decomposition. In order to improve our predictive capabilities, we use a chronosequence thaw slumps to examine how fluxes from active and stabilized features differ. Our study site is along the Selawik River in northwest Alaska where a retrogressive thaw slump initiated in the spring of 2004. It has grown to a surface area of 50,000 m2. Products of the erosion are stored on the floor of the feature, trapped on a fan or flushed into the Selawik River. North of slump is undisturbed tundra and adjacent to the west is a slump feature that stabilized and is now covered with a second generation of spruce trees. In this 2 year study, we use measurements of CO2 efflux, δC13 in soil profiles and CO2 and CH4 abundance to constrain the response of belowground carbon emissions. We also focused on constraining which environmental factors govern C emissions within each of the above ecosystems. To this end, we measured soil temperature, and moisture, abundance and quality of soil organic carbon (SOC), water content, and bulk carbon compositions. Preliminary data from the summer of 2011 suggest that vegetation composition and soil temperature exert the strong control on CO2 efflux. The floor of the active slump and fan are bare mineral soils and are generally 10 to 15°C warmer than the tundra and stabilized slump. Consistently decreasing δC13 soil gas profiles in the recovered slump confirm that this region is a well-drained soil dominated by C3 vegetation. The δC13 gas profiles for the tundra, active slump

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

    SciTech Connect

    McVey, M.D.; Goering, T.J.; Peace, J.L.

    1996-02-01

    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.

  4. Increased radon-222 in soil gas because of cumulative seismicity at active faults

    NASA Astrophysics Data System (ADS)

    Koike, Katsuaki; Yoshinaga, Tohru; Ueyama, Takayoshi; Asaue, Hisafumi

    2014-12-01

    This study demonstrates how the radon-222 (222Rn) concentration of soil gas at an active fault is sensitive to cumulative recent seismicity by examining seven active faults in western Japan. The 222Rn concentration was found to correlate well with the total earthquake energy within a 100-km radius of each fault. This phenomenon can probably be ascribed to the increase of pore pressure around the source depth of 222Rn in shallow soil caused by frequently induced strain. This increase in pore pressure can enhance the ascent velocity of 222Rn carrier gas as governed by Darcy's law. Anomalous 222Rn concentrations are likely to originate from high gas velocities, rather than increased accumulations of parent nuclides. The high velocities also can yield unusual young gas under the radioactive nonequilibrium condition of short elapsed time since 222Rn generation. The results suggest that ongoing seismicity in the vicinity of an active fault can cause accumulation of strain in shallow fault soils. Therefore, the 222Rn concentration is a possible gauge for the degree of strain accumulation.

  5. Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

    SciTech Connect

    Bond-Lamberty, Benjamin; Smith, Ashly P.; Bailey, Vanessa L.

    2016-12-21

    Rapid climatic changes, rising air temperatures, and increased fires are expected to drive permafrost degradation and alter soil carbon (C) cycling in many high-latitude ecosystems. How these soils will respond to changes in their temperature, moisture, and overlying vegetation is highly uncertain, but critical to understand given the large soil C stocks in these regions. We used a laboratory experiment to examine how temperature and moisture control CO2 and CH4 emissions from mineral soils sampled from the bottom of the annual active layer, i.e. directly above permafrost, in an Alaskan boreal forest. Gas emissions from thirty cores, subjected to two temperatures and either field moisture conditions or experimental drought, were tracked over a 100-day incubation; we also measured a variety of physical and chemical characteristics of the cores. Gravimetric water content was 0.31 ± 0.12 (unitless) at the beginning of the incubation; cores at field moisture were unchanged at the end, but drought cores had declined to 0.06 ± 0.04. Carbon dioxide fluxes were strongly influenced by incubation chamber temperature, core water content, and percent soil nitrogen, and had a temperature sensitivity (i.e. Q10) of 1.3 and 1.9 for the field moisture and drought treatments, respectively. Methane emissions were most strongly correlated with percent nitrogen, but neither temperature nor water content was a significant first-order predictor of CH4 fluxes. The cumulative production of C from CO2 was over six orders of magnitudes higher than that from CH4. These results suggest that deep active-layer soils may be much more sensitive to changes in moisture than to temperature, a critical factor as discontinuous permafrost melts in interior Alaska. Deep but unfrozen high-latitude soils have been shown to be strongly affected by long-term experimental warming, and these results provide insight into their future dynamics and feedback potential with future climate change.

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

    PubMed

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

    2014-05-01

    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.

  7. Soil Gas Sampling

    EPA Pesticide Factsheets

    Field Branches Quality System and Technical Procedures: This document describes general and specific procedures, methods and considerations to be used and observed when collecting soil gas samples for field screening or laboratory analysis.

  8. Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

    NASA Astrophysics Data System (ADS)

    Bond-Lamberty, Ben; Smith, A. Peyton; Bailey, Vanessa

    2016-12-01

    Rapid climatic changes, rising air temperatures, and increased fires are expected to drive permafrost degradation and alter soil carbon (C) cycling in many high-latitude ecosystems. How these soils will respond to changes in their temperature, moisture, and overlying vegetation is uncertain but critical to understand given the large soil C stocks in these regions. We used a laboratory experiment to examine how temperature and moisture control CO2 and CH4 emissions from mineral soils sampled from the bottom of the annual active layer, i.e., directly above permafrost, in an Alaskan boreal forest. Gas emissions from 30 cores, subjected to two temperatures and either field moisture conditions or experimental drought, were tracked over a 100-day incubation; we also measured a variety of physical and chemical characteristics of the cores. Gravimetric water content was 0.31 ± 0.12 (unitless) at the beginning of the incubation; cores at field moisture were unchanged at the end, but drought cores had declined to 0.06 ± 0.04. Daily CO2 fluxes were positively correlated with incubation chamber temperature, core water content, and percent soil nitrogen. They also had a temperature sensitivity (Q10) of 1.3 and 1.9 for the field moisture and drought treatments, respectively. Daily CH4 emissions were most strongly correlated with percent nitrogen, but neither temperature nor water content was a significant first-order predictor of CH4 fluxes. The cumulative production of C from CO2 was over 6 orders of magnitude higher than that from CH4; cumulative CO2 was correlated with incubation temperature and moisture treatment, with drought cores producing 52-73 % lower C. Cumulative CH4 production was unaffected by any treatment. These results suggest that deep active-layer soils may be sensitive to changes in soil moisture under aerobic conditions, a critical factor as discontinuous permafrost thaws in interior Alaska. Deep but unfrozen high-latitude soils have been shown to be

  9. Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

    DOE PAGES

    Bond-Lamberty, Ben; Smith, A. Peyton; Bailey, Vanessa

    2016-12-21

    Rapid climatic changes, rising air temperatures, and increased fires are expected to drive permafrost degradation and alter soil carbon (C) cycling in many high-latitude ecosystems. How these soils will respond to changes in their temperature, moisture, and overlying vegetation is uncertain but critical to understand given the large soil C stocks in these regions. We used a laboratory experiment to examine how temperature and moisture control CO2 and CH4 emissions from mineral soils sampled from the bottom of the annual active layer, i.e., directly above permafrost, in an Alaskan boreal forest. Gas emissions from 30 cores, subjected to two temperaturesmore » and either field moisture conditions or experimental drought, were tracked over a 100-day incubation; we also measured a variety of physical and chemical characteristics of the cores. Gravimetric water content was 0.31 ± 0.12 (unitless) at the beginning of the incubation; cores at field moisture were unchanged at the end, but drought cores had declined to 0.06 ± 0.04. Daily CO2 fluxes were positively correlated with incubation chamber temperature, core water content, and percent soil nitrogen. They also had a temperature sensitivity (Q10) of 1.3 and 1.9 for the field moisture and drought treatments, respectively. Daily CH4 emissions were most strongly correlated with percent nitrogen, but neither temperature nor water content was a significant first-order predictor of CH4 fluxes. The cumulative production of C from CO2 was over 6 orders of magnitude higher than that from CH4; cumulative CO2 was correlated with incubation temperature and moisture treatment, with drought cores producing 52–73 % lower C. Cumulative CH4 production was unaffected by any treatment. These results suggest that deep active-layer soils may be sensitive to changes in soil moisture under aerobic conditions, a critical factor as discontinuous permafrost thaws in interior Alaska. Deep but unfrozen high-latitude soils have

  10. Soil-gas radon concentration monitoring in an active granite quarry from Central Portugal

    NASA Astrophysics Data System (ADS)

    Neves, Luís.; Barbosa, Susana; Pereira, Alcides; Aumento, Fabrizio

    2010-05-01

    This study was carried out in an active quarry located nearby the town of Nelas (Central Portugal), with the primary objective of assessing the effect of regular explosions on soil-gas radon concentrations. Here, a late-orogenic Hercynian porphyritic biotite granite occurs and is exploited for the production of high quality aggregates for different building purposes. This granite is part of the Beiras batholiths, being a geochemically moderately evolved rock, slightly peraluminous, and widely known by the frequent occurrence of associated uranium mineralizations. In fact, more than 4000t of U3O8 was produced from 60 mines of the Beiras region in the last century, over a wide area of more than 10.000 km2, and thousands of anomalies related with the local accumulation of uranium in fault filling materials, metasedimentary enclaves and doleritic veins were recognized during prospecting works. The heterogeneity of uranium distribution in this rock is reflected at the test site; indeed, a gamma ray survey shows that some of the faults that occur in the quarry are slightly mineralized. A total of 7 radon monitoring stations were implemented in the quarry, at a typical depth comprised between 1 and 2 meters, in holes drilled for the purpose. Aware RM-70 pancake GM detectors were used, sensitive to alpha, beta and gamma/X-rays above 10 keV, connected to palmtop computers for data registration (1 minute interval) and power supplied by batteries. Monitoring was carried out during 6 months, in Spring/Summer conditions and the exact time of each explosion was registered manually. Several problems of data loss and power supply affected the stations during the experiment, leading to discontinuities in the records. Still the available data showed important differences in the soil-gas radon concentrations between stations, which can be explained by the heterogeneity of uranium distribution in the rock and increased local permeability. Furthermore, all stations showed a clear daily

  11. Activity, distribution, and abundance of methane-oxidizing bacteria in the near surface soils of onshore oil and gas fields.

    PubMed

    Xu, Kewei; Tang, Yuping; Ren, Chun; Zhao, Kebin; Wang, Wanmeng; Sun, Yongge

    2013-09-01

    Methane-oxidizing bacteria (MOB) have long been used as an important biological indicator for oil and gas prospecting, but the ecological characteristics of MOB in hydrocarbon microseep systems are still poorly understood. In this study, the activity, distribution, and abundance of aerobic methanotrophic communities in the surface soils underlying an oil and gas field were investigated using biogeochemical and molecular ecological techniques. Measurements of potential methane oxidation rates and pmoA gene copy numbers showed that soils inside an oil and gas field are hot spots of methane oxidation and MOB abundance. Correspondingly, terminal restriction fragment length polymorphism analyses in combination with cloning and sequencing of pmoA genes also revealed considerable differences in the methanotrophic community composition between oil and gas fields and the surrounding soils. Principal component analysis ordination furthermore indicated a coincidence between elevated CH4 oxidation activity and the methanotrophic community structure with type I methanotrophic Methylococcus and Methylobacter, in particular, as indicator species of oil and gas fields. Collectively, our results show that trace methane migrated from oil and gas reservoirs can considerably influence not only the quantity but also the structure of the methanotrophic community.

  12. Reduced greenhouse gas mitigation potential of no-tillage soils through earthworm activity

    PubMed Central

    Lubbers, Ingrid M.; Jan van Groenigen, Kees; Brussaard, Lijbert; van Groenigen, Jan Willem

    2015-01-01

    Concerns about rising greenhouse gas (GHG) concentrations have spurred the promotion of no-tillage practices as a means to stimulate carbon storage and reduce CO2 emissions in agro-ecosystems. Recent research has ignited debate about the effect of earthworms on the GHG balance of soil. It is unclear how earthworms interact with soil management practices, making long-term predictions on their effect in agro-ecosystems problematic. Here we show, in a unique two-year experiment, that earthworm presence increases the combined cumulative emissions of CO2 and N2O from a simulated no-tillage (NT) system to the same level as a simulated conventional tillage (CT) system. We found no evidence for increased soil C storage in the presence of earthworms. Because NT agriculture stimulates earthworm presence, our results identify a possible biological pathway for the limited potential of no-tillage soils with respect to GHG mitigation. PMID:26337488

  13. Automated soil gas monitoring chamber

    DOEpatents

    Edwards, Nelson T.; Riggs, Jeffery S.

    2003-07-29

    A chamber for trapping soil gases as they evolve from the soil without disturbance to the soil and to the natural microclimate within the chamber has been invented. The chamber opens between measurements and therefore does not alter the metabolic processes that influence soil gas efflux rates. A multiple chamber system provides for repetitive multi-point sampling, undisturbed metabolic soil processes between sampling, and an essentially airtight sampling chamber operating at ambient pressure.

  14. Impact of biochar application to a Mediterranean wheat crop on soil microbial activity and greenhouse gas fluxes.

    PubMed

    Castaldi, S; Riondino, M; Baronti, S; Esposito, F R; Marzaioli, R; Rutigliano, F A; Vaccari, F P; Miglietta, F

    2011-11-01

    Biochar has been recently proposed as a management strategy to improve crop productivity and global warming mitigation. However, the effect of such approach on soil greenhouse gas fluxes is highly uncertain and few data from field experiments are available. In a field trial, cultivated with wheat, biochar was added to the soil (3 or 6 kg m(-2)) in two growing seasons (2008/2009 and 2009/2010) so to monitor the effect of treatments on microbial parameters 3 months and 14 months after char addition. N(2)O, CH(4) and CO(2) fluxes were measured in the field during the first year after char addition. Biochar incorporation into the soil increased soil pH (from 5.2 to 6.7) and the rates of net N mineralization, soil microbial respiration and denitrification activity in the first 3 months, but after 14 months treated and control plots did not differ significantly. No changes in total microbial biomass and net nitrification rate were observed. In char treated plots, soil N(2)O fluxes were from 26% to 79% lower than N(2)O fluxes in control plots, excluding four sampling dates after the last fertilization with urea, when N(2)O emissions were higher in char treated plots. However, due to the high spatial variability, the observed differences were rarely significant. No significant differences of CH(4) fluxes and field soil respiration were observed among different treatments, with just few exceptions. Overall the char treatments showed a minimal impact on microbial parameters and GHG fluxes over the first 14 months after biochar incorporation.

  15. Regional and Detailed Survey for Radon Activities in Soil-Gas and Groundwater in the Okchon Zone, Korea

    NASA Astrophysics Data System (ADS)

    Je, H.-K.; Chon, H.-T.

    2012-04-01

    The Okchon zone in Korea provides a typical example of natural geological materials enriched in potentially toxic elements including uranium which is parent nuclide for radon gas. For the purpose of radon radioactivity risk assessment, making the map of radon risk grade from Okchon zone, regional and detailed field surveys were carried out during 3 years. The study area is located in the central part of Korea, called the Okchon zone (about 5,100 km2), which occur in a 80km wide, northeast-trending belt that extends across the Korean Peninsula. The Okchon zone is underlain by metasedimentary rocks of unknown age that are composed mainly of black slate, phyllite, shale, and limestone. The three research areas (defined as Boeun, Chungju, and Nonsan) for detailed survey were selected from the results of regional survey. Results of detailed radon survey indicated a wide range of radon activities for soil-gases (148-1,843 pCi/L) and ground waters (23-5,540 pCi/L). About 15 percent of soil-gas samples exceeded 1,000 pCi/L and 84 percent of ground water samples exceeded the MCL (maximum contaminant level) of drinking water, 300 pCi/L, which proposed by U.S. Environmental Protection Agency in 1999. For detailed survey, radon activities of soil-gas and ground water were classified as bedrock geology, based on 1/50,000 geological map and field research. For soil-gas measurements, mean values of radon activity from black slate-shale (789 pCi/L) were highest among the other base rocks. And for groundwater measurements, mean value of radon activities were decreased in the order of granite (1,345 pCi/L) > black shale-slate (915 pCi/L) > metasediments (617 pCi/L). Result of indoor radon measurement from detailed survey areas showed that about 50% of houses exceeded the indoor guideline, 4 pCi/L. For the radon risk assessment in indoor environment showed that probability of lung cancer risk from the houses located on the granite base rock (3.0×10-2) was highest among the other

  16. Analysis of volatile phase transport in soils using natural radon gas as a tracer

    SciTech Connect

    Chen, C.; Thomas, D.M.

    1992-12-31

    We have conducted a field study of soil gas transport processes using radon gas as a naturally occurring tracer. The .experiment monitored soil gas radon activity, soil moisture, and soil temperature at three depths in the shallow soil column; barometric pressure, rainfall and wind speed were monitored at the soil surface. Linear and multiple regression analysis of the data sets has shown that the gas phase radon activities under natural environmental conditions are influenced by soil moisture content, barometric pressure variations, soil temperature and soil structure. The effect of wind speed on subsurface radon activities under our field conditions has not been demonstrated.

  17. Analysis of volatile phase transport in soils using natural radon gas as a tracer

    SciTech Connect

    Chen, C.; Thomas, D.M.

    1992-01-01

    We have conducted a field study of soil gas transport processes using radon gas as a naturally occurring tracer. The .experiment monitored soil gas radon activity, soil moisture, and soil temperature at three depths in the shallow soil column; barometric pressure, rainfall and wind speed were monitored at the soil surface. Linear and multiple regression analysis of the data sets has shown that the gas phase radon activities under natural environmental conditions are influenced by soil moisture content, barometric pressure variations, soil temperature and soil structure. The effect of wind speed on subsurface radon activities under our field conditions has not been demonstrated.

  18. The Martian Soil: A Planetary Gas Pump

    NASA Astrophysics Data System (ADS)

    De Beule, Caroline; Wurm, G.; Thorben, K.; Küpper, M.; Jankowski, T.; Teiser, J.

    2013-10-01

    The transport of gas through the Martian soil plays an important role in processes like the global cycle of water. Until now, in the absence of an active pumping system, diffusion was assumed to be the most efficient transport mechanism. Here, we present a new mechanism of forced convection within porous soils, which occurs naturally on Mars. In the low pressure environment of Mars, thermal creep within the insolated surface can act as an efficient pump in the porous soil. The pores of the dust act as micro-channels, where the gas flows from the cold to the warm side. We proved this concept in drop tower experiments. In microgravity thermal convection is absent and only thermal creep is visible. By illuminating a basaltic dust bed in microgravity, it was possible to trace the gas flow by embedded particles, moving towards the dust bed within shadowed regions with inflow velocities on the order of cm/s. These observations are consistent with a model of forced flow through the porous medium. Scaled to Martian conditions the experiments show that this transport mechanism can be very efficient and atmospheric gas can be pumped into the soil in shadowed parts and be transported underground to insolated places. This natural planet wide pump is unique in the Solar System as only the Martian surface conditions (mbar pressure) are suitable for this effect.

  19. Final Project Report for the Development of an Active Soil Gas Sampling Method

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the nation's natural resources. Under the mandate of national environmental laws, the EPA strives to formulate and implement actions leading to a compatible balance between human activities and ...

  20. Impact of flue gas desulfurization-calcium sulfite and gypsum on soil microbial activity and wheat growth

    SciTech Connect

    Lee, Y.B.; Bigham, J.M.; Dick, W.A.; Kim, P.J.

    2008-08-15

    We conducted greenhouse tests to evaluate the effects of FGD-CaSO{sub 3} applied at rates of 0, 2.2, 4.4, and 8.8 Mg ha(-1) on wheat growth, soil enzyme activities, and the chemical properties of two soils with differing pH (4.0 vs. 6.2). A gypsum treatment applied at the rate of 2.2 Mg ha{sup -1} was used as a positive control. Exchangeable Ca{sup 2+} and water-extractable Ca{sup 2+} and SO{sub 4}{sup 2-} increased significantly with increasing FGD-CaSO{sub 3} application. SO{sub 4}{sup 2-} increased in both soils, indicating rapid oxidation of SO{sub 3}{sup 2-} to SO{sub 4}{sup 2-} when neither water nor oxygen was limiting. No changes in soil pH were measured. Applications of 2.2, 4.4, or 8.8 Mg CaSO{sub 3} ha{sup -1} to the pH 6.2 soil produced no effect on wheat growth or the uptake of N, P, Ca{sup 2+}, and Mg{sup 2+}. The uptake of SO{sub 4}{sup 2-} -S increased, whereas K uptake decreased. No significant differences in the activities of urease, {beta}-glucosidase, alkaline phosphatase, or arylsulfatase were observed relative to a control. In the acid soil, an application of 2.2 Mg ha{sup -1} FGD-CaSO{sub 3} increased wheat root growth and dry matter yield compared with an untreated control. The uptake of N, P, Ca{sup 2+}, and K{sup +} also increased presumably because of enhanced root development resulting from decreases in exchangeable Al{sup 3+} and increases in soluble Ca{sup 2+}. Wheat growth and alkaline phosphatase and arylsulfatase activities were significantly inhibited by addition of 8.8 Mg ha{sup -1} of FGD-CaSO{sub 3} compared with the untreated control or the same soil receiving 2.2 Mg ha{sup -1} gypsum. We conclude that surface applications of FGD-CaSO{sub 3} may be as effective as gypsum for inhibiting soil crusting, improving water infiltration, and promoting the movement of Ca{sup 2+} into acid subsoils. Moreover, application rates of equal to or less than 4.4 Mg ha-1 should have no negative impact on soil microbial activities or plant growth.

  1. Soil gas oxygen tension and pentachlorophenol biodegradation

    SciTech Connect

    Hurst, C.J.; Sims, R.C.; Sims, J.L.; Sorensen, D.L.; McLean, J.E.; Huling, S.

    1997-04-01

    Laboratory tests were conducted to determine the effect of soil gas oxygen concentration on the degradation and mineralization of spiked {sup 14}C-pentachlorophenol and nonlabeled pentachlorophenol (PCP) present in soil taken from a prepared-bed land treatment unit at the Champion International Superfund Site in Libby, Mont. This soil was contaminated with wood preserving wastes including creosote and PCP. Degradation rates of {sup 14}C-PCP and nonlabeled PCP were found to be enhanced under soil gas oxygen concentrations between 2 and 21% in the contaminated soil. Between 48 and 64% of {sup 14}C-PCP spiked onto the soil was mineralized after 70 days at soil gas oxygen levels between 2 and 21%. No statistically significant mineralization of PCP was found to occur at 0% oxygen concentrations. Mineralization of {sup 14}C-PCP in contaminated soil poisoned with mercuric chloride was determined to be less than 0.2%. Degradation of indigenous nonradiolabeled PCP in the nonpoisoned soil was statistically significantly greater than in poisoned soil. These results indicated that degradation of PCP was biological and would occur under low oxygen concentrations. Soil gas oxygen concentrations necessary for PCP biodegradation (2--5%) could be maintained, for example, using bioventing technology in order to achieve continued treatment of buried lifts of soil while new lifts are added, thus decreasing the total time for soil remediation of the prepared bed.

  2. LEAK AND GAS PERMEABILITY TESTING DURING SOIL-GAS SAMPLING AT HAL'S CHEVRON LUST SITE IN GREEN RIVER, UTAH

    EPA Science Inventory

    The results of gas permeability and leak testing during active soil-gas sampling at Hal’s Chevron LUST Site in Green River, Utah are presented. This study was conducted to support development of a passive soil-gas sampling method. Gas mixtures containing helium and methane were...

  3. Indoor radon prediction from soil gas measurements.

    PubMed

    Varley, N R; Flowers, A G

    1998-06-01

    This study of radon levels in southwest England investigates the correlation between indoor and soil gas radon concentrations and considers the influence of geology, meteorological variables, spatial and depth variations. This paper examines the value of soil gas measurements as an indicator of potential indoor radon concentrations and highlights a number of factors that need to be considered. Only a very weak correlation was obtained between the overall 222Rn concentration in soil gas and inside the home. However, for high soil gas concentrations a stronger correlation with the indoor level was observed. Typically, the soil gas concentration was between a factor of 10 and 1,000 times greater than that indoors. Levels as low as 10 kBq m(-3) in the soil could produce an indoor concentration above the UK action level of 200 Bq m(-3). The moisture content and the inhomogeneity of soil permeability were identified as chiefly responsible for any perturbation of a soil gas concentration associated with a particular geology. Alone, measured soil gas concentrations have only a limited use in the prediction of indoor 222Rn concentrations.

  4. Analysis of volatile-phase transport in soils using natural radon gas as a tracer

    SciTech Connect

    Chen, C.; Thomas, D.M.

    1994-01-01

    We have conducted a field study of soil gas transport processes using radon gas as a naturally occurring tracer. The experiment monitored soil gas radon activity, soil moisture, and soil temperature at depth; barometric pressure, rainfall, and wind speed were monitored at the soil surface. Linear and multiple regression analysis under natural environmental conditions are influenced by soil moisture content, barometric pressure variations, soil temperature, and soil structure. The effect of wind speed on subsurface radon activities under our field conditions has not been observed. 25 refs., 12 figs., 1 tab.

  5. SOIL GAS OXYGEN TENSION AND PENTACHLOROPHENOL BIODEGRADATION

    EPA Science Inventory

    Laboratory tests were conducted to determine the effect of soil gas oxygen concentration on the degradation and mineralization of spiked 14C-pentachlorophenol and nonlabeled pentachlorophenol (PCP) present in soil taken from a prepared-bed land treatment unit at the Champion Inte...

  6. Radon in soil gas in Kosovo.

    PubMed

    Kikaj, Dafina; Jeran, Zvonka; Bahtijari, Meleq; Stegnar, Peter

    2016-11-01

    An assessment of the radiological situation due to exposure to radon and gamma emitting radionuclides was conducted in southern Kosovo. This study deals with sources of radon in soil gas. A long-term study of radon concentrations in the soil gas was carried out using the SSNTDs (CR-39) at 21 different locations in the Sharr-Korabi zone. The detectors were exposed for an extended period of time, including at least three seasonal periods in a year and the sampling locations were chosen with respect to lithology. In order to determine the concentration of the natural radioactive elements (238)U and (226)Ra, as a precursor of (222)Rn, soil samples were collected from each measuring point from a depth of 0.8 m, and measured by gamma spectrometry. The levels (Bq kg(-1)) of naturally occurring radionuclides and levels (kBq m(-3)) of radon in soil gas obtained at a depth 0.8 m of soil were: 21-53 for (226)Ra, 22-160 for (238)U and 0.295-32 for (222)Rn. With respect to lithology, the highest value for (238)U and (226)Ra were found in limestone and the highest value for (222)Rn was found in metamorphic rocks. In addition, the results showed seasonal variations of the measured soil gas radon concentrations with maximum concentration in the spring months.

  7. Soil moisture by extraction and gas chromatography

    NASA Technical Reports Server (NTRS)

    Merek, E. L.; Carle, G. C.

    1973-01-01

    To determine moisture content of soils rapidly and conveniently extract moisture with methanol and determine water content of methanol extract by gas chromatography. Moisture content of sample is calculated from weight of water and methanol in aliquot and weight of methanol added to sample.

  8. A new in-situ method to determine the apparent gas diffusion coefficient of soils

    NASA Astrophysics Data System (ADS)

    Laemmel, Thomas; Paulus, Sinikka; Schack-Kirchner, Helmer; Maier, Martin

    2015-04-01

    Soil aeration is an important factor for the biological activity in the soil and soil respiration. Generally, gas exchange between soil and atmosphere is assumed to be governed by diffusion and Fick's Law is used to describe the fluxes in the soil. The "apparent soil gas diffusion coefficient" represents the proportional factor between the flux and the gas concentration gradient in the soil and reflects the ability of the soil to "transport passively" gases through the soil. One common way to determine this coefficient is to take core samples in the field and determine it in the lab. Unfortunately this method is destructive and needs laborious field work and can only reflect a small fraction of the whole soil. As a consequence insecurity about the resulting effective diffusivity on the profile scale must remain. We developed a new in-situ method using new gas sampling device, tracer gas and inverse soil gas modelling. The gas sampling device contains several sampling depths and can be easily installed into vertical holes of an auger, which allows for fast installation of the system. At the lower end of the device inert tracer gas is injected continuously. The tracer gas diffuses into the surrounding soil. The resulting distribution of the tracer gas concentrations is used to deduce the diffusivity profile of the soil. For Finite Element Modeling of the gas sampling device/soil system the program COMSOL is used. We will present the results of a field campaign comparing the new in-situ method with lab measurements on soil cores. The new sampling pole has several interesting advantages: it can be used in-situ and over a long time; so it allows following modifications of diffusion coefficients in interaction with rain but also vegetation cycle and wind.

  9. Soil gas 222Rn concentration in northern Germany and its relationship with geological subsurface structures.

    PubMed

    Künze, N; Koroleva, M; Reuther, C-D

    2013-01-01

    (222)Rn in soil gas activity was measured across the margins of two active salt diapirs in Schleswig-Holstein, northern Germany, in order to reveal the impact of halokinetic processes on the soil gas signal. Soil gas and soil sampling were carried out in springtime and summer 2011. The occurrence of elevated (222)Rn in soil gas concentrations in Schleswig-Holstein has been ascribed to radionuclide rich moraine boulder material deposits, but the contribution of subsurface structures has not been investigated so far. Reference samples were taken from a region known for its granitic moraine boulder deposits, resulting in (222)Rn in soil gas activity of 40 kBq/m(3). The values resulting from profile sampling across salt dome margins are of the order of twice the moraine boulder material reference values and exceed 100 kBq/m(3). The zones of elevated concentrations are consistent throughout time despite variations in magnitude. One soil gas profile recorded in this work expands parallel to a seismic profile and reveals multiple zones of elevated (222)Rn activities above a rising salt intrusion. The physical and chemical properties of salt have an impact on the processes influencing gas migration and surface near radionuclide accumulations. The rise of salt supports the breakup of rock components thus leading to enhanced emanation. This work provides a first approach regarding the halokinetic contribution to the (222)Rn in soil gas occurrence and a possible theoretical model which summarizes the relevant processes was developed.

  10. Soil-gas radon as seismotectonic indicator in Garhwal Himalaya.

    PubMed

    Ramola, R C; Prasad, Yogesh; Prasad, Ganesh; Kumar, Sushil; Choubey, V M

    2008-10-01

    Research on earthquake-related radon monitoring has received enormous attention recently. Anomalous behaviour of radon in soil and groundwater can be used as a reliable precursor for an impending earthquake. While earthquake prediction may not yet be possible, earthquake prediction research has greatly increased our understanding of earthquake source mechanisms, the structural complexities of fault zones, and the earthquake recurrence interval, expected at a given location. This paper presents some results of continuous monitoring of radon in soil-gas in Garhwal Himalaya, India. Daily soil-gas radon monitoring with seismic activity and meteorological parameters were performed in the same laboratory system, located at H.N.B. Garhwal University Campus, Tehri Garhwal, India. Radon anomalies along with meteorological parameters were found to be statistically significant for the seismic events within the magnitudes M2.0-M6.0 and epicentral distances of 16-250 km from the monitoring station. The frequent positive and negative anomalies with constant environmental perturbation indicate the opening and closing of micro cracks within the volume of dilatancy by strain energy. The spike-like and sharp peak anomalies were recorded before, during and after earthquakes occurred in the area. The variations in radon concentrations in soil-gas are found to be correlated with seismic activities in the Garhwal Himalaya. The correlation between radon level and meteorological parameters is also discussed.

  11. Impact of repeated dry-wet cycles on soil greenhouse gas emissions, extracellular enzyme activity and nutrient cycling in a temperate forest

    NASA Astrophysics Data System (ADS)

    Leitner, Sonja; Zimmermann, Michael; Bockholt, Jan; Schartner, Markus; Brugner, Paul; Holtermann, Christian; Zechmeister-Boltenstern, Sophie

    2014-05-01

    Climate change research predicts that both frequency and intensity of weather extremes such as long drought periods and heavy rainfall events will increase in mid Europe over the next decades. Soil moisture is one of the major factors controlling microbial soil processes, and it has been widely agreed that feedback effects between altered precipitation and changed soil fluxes of the greenhouse gases CO2, CH4 and N2O could intensify climate change. In a field experiment in an Austrian beech forest, we established a precipitation manipulation experiment, which will be conducted for 3 years. We use roofs to exclude rainfall from reaching the forest soil and simulate drought periods, and a sprinkler system to simulate heavy rainfall events. We applied repeated dry-wet cycles in two intensities: one treatment received 6 cycles of 1 month drought followed by 75mm irrigation within 2 hours, and a parallel treatment received 3 cycles of 2 months drought followed by 150mm irrigation within 3 hours. We took soil samples 1 day before, 1 day after and 1 week after rewetting events and analyzed them for soil nutrients and extracellular enzyme activities. Soil fluxes of CO2, N2O and CH4 were constantly monitored with an automated flux chamber system, and environmental parameters were recorded via dataloggers. In addition, we determined fluxes and nutrient concentrations of bulk precipitation, throughfall, stemflow, litter percolate and soil water. Next we plan to analyze soil microbial community composition via PLFAs to investigate microbial stress resistance and resilience, and we will use ultrasonication to measure soil aggregate stability and protection of soil organic matter in stressed and control plots. The results of the first year show that experimental rainfall manipulation has influenced soil extracellular enzymes. Potential phenoloxidase activity was significantly reduced in stressed treatments compared to control plots. All measured hydrolytic enzymes (cellulase

  12. DUS II SOIL GAS SAMPLING AND AIR INJECTION TEST RESULTS

    SciTech Connect

    Noonkester, J.; Jackson, D.; Jones, W.; Hyde, W.; Kohn, J.; Walker, R.

    2012-09-20

    Soil vapor extraction (SVE) and air injection well testing was performed at the Dynamic Underground Stripping (DUS) site located near the M-Area Settling Basin (referred to as DUS II in this report). The objective of this testing was to determine the effectiveness of continued operation of these systems. Steam injection ended on September 19, 2009 and since this time the extraction operations have utilized residual heat that is present in the subsurface. The well testing campaign began on June 5, 2012 and was completed on June 25, 2012. Thirty-two (32) SVE wells were purged for 24 hours or longer using the active soil vapor extraction (ASVE) system at the DUS II site. During each test five or more soil gas samples were collected from each well and analyzed for target volatile organic compounds (VOCs). The DUS II site is divided into four parcels (see Figure 1) and soil gas sample results show the majority of residual VOC contamination remains in Parcel 1 with lesser amounts in the other three parcels. Several VOCs, including tetrachloroethylene (PCE) and trichloroethylene (TCE), were detected. PCE was the major VOC with lesser amounts of TCE. Most soil gas concentrations of PCE ranged from 0 to 60 ppmv with one well (VEW-22A) as high as 200 ppmv. Air sparging (AS) generally involves the injection of air into the aquifer through either vertical or horizontal wells. AS is coupled with SVE systems when contaminant recovery is necessary. While traditional air sparging (AS) is not a primary component of the DUS process, following the cessation of steam injection, eight (8) of the sixty-three (63) steam injection wells were used to inject air. These wells were previously used for hydrous pyrolysis oxidation (HPO) as part of the DUS process. Air sparging is different from the HPO operations in that the air was injected at a higher rate (20 to 50 scfm) versus HPO (1 to 2 scfm). . At the DUS II site the air injection wells were tested to determine if air sparging affected

  13. Should soil testing services measure soil biological activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Health of agricultural soils depends largely on conservation management to promote soil organic C accumulation. Total soil organic C changes slowly, but active fractions are more dynamic. A key indicator of healthy soil is potential biological activity, which could be measured rapidly with soil te...

  14. Poly-Use Multi-Level Sampling Rod to Measure Soil-Gas Exchange in Glacier Forefield Soils

    NASA Astrophysics Data System (ADS)

    Nauer, P. A.; Schroth, M. H.; Zeyer, J. A.

    2012-12-01

    The forefields of receding glaciers provide unique opportunities to investigate initial microbial processes in the vadose zone and their role in soil formation. Various studies revealed a surprising diversity of microbes and of their strategies to cope with the extreme conditions in this C- and N-limited environment. In the forefield of receding glaciers as well as in developed soils microorganisms are the driving force for the exchange of greenhouse gases between soil and atmosphere. However, in young and developing soils, little is known about soil-gas exchange and the activities of the involved microorganisms. Knowledge of soil-gas composition and gas diffusion at various depths in a soil profile allows for the precise calculation of gas fluxes among different depths within the vadose zone and at the soil-atmosphere boundary. The acquisition of undisturbed soil-gas samples at a high depth-resolution is difficult, and the estimation of soil-gas diffusion coefficients requires knowledge of volumetric water content at the exact location of gas sampling. By using conventional techniques, e.g. the burial of permanent probes, these tasks are virtually impossible to accomplish in a remote glacier forefield dominated by rocks and boulders. We developed a novel poly-use multi-level sampling rod (PULSAR) primarily consisting of two devices: a newly-designed multi-level sampler (MLS) for soil-gas sampling, and a commercially available profile probe (PR2) for non-invasive multi-level water content measurements. These devices fit into the same access tubes (ATs) of 1.1m length, which need to be pre-installed into the soil with the help of a steel rod. We modified the ATs to feature eight 1mm diameter holes each at 20 sampling depths in intervals of 5cm. Our MLS can be inserted into the ATs and allows for the selective extraction of soil-gas from each sampling depth. The interspaces between the sampling depths are sealed by inflatable rubber membranes for the time of sampling

  15. Soil gas investigations at the Sanitary Landfill

    SciTech Connect

    Wyatt, D.E.; Pirkle, R.J.; Masdea, D.J.

    1992-07-01

    A soil gas survey was performed at the 740-G Sanitary Landfill of Savannah River Plant during December, 1990. The survey monitored the presence and distribution of the C[sub 1]C[sub 4] hydrocarbons; the C[sub 5]-C[sub 10] normal paraffins; the aromatic hydrocarbons, BTXE; selected chlorinated hydrocarbons; and mercury. Significant levels of several of these contaminants were found associated with the burial site. In the northern area of the Landfill, methane concentrations ranged up to 63% of the soil gas and were consistently high on the western side of the access road. To the east of the access road in the northern and southern area high concentrations of methane were encountered but were not consistently high. Methane, the species found in highest concentration in the landfill, was generated in the landfill as the result of biological oxidation of cellulose and other organics to carbon dioxide followed by reduction of the carbon dioxide to methane. Distributions of other species are the result of burials in the landfill of solvents or other materials.

  16. Soil gas investigations at the Sanitary Landfill

    SciTech Connect

    Wyatt, D.E.; Pirkle, R.J.; Masdea, D.J.

    1992-07-01

    A soil gas survey was performed at the 740-G Sanitary Landfill of Savannah River Plant during December, 1990. The survey monitored the presence and distribution of the C{sub 1}C{sub 4} hydrocarbons; the C{sub 5}-C{sub 10} normal paraffins; the aromatic hydrocarbons, BTXE; selected chlorinated hydrocarbons; and mercury. Significant levels of several of these contaminants were found associated with the burial site. In the northern area of the Landfill, methane concentrations ranged up to 63% of the soil gas and were consistently high on the western side of the access road. To the east of the access road in the northern and southern area high concentrations of methane were encountered but were not consistently high. Methane, the species found in highest concentration in the landfill, was generated in the landfill as the result of biological oxidation of cellulose and other organics to carbon dioxide followed by reduction of the carbon dioxide to methane. Distributions of other species are the result of burials in the landfill of solvents or other materials.

  17. Active synthetic soil

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W. (Inventor); Henninger, Donald L. (Inventor); Allen, Earl R. (Inventor); Golden, Dadigamuwage C. (Inventor)

    1995-01-01

    A synthetic soil/fertilizer for horticultural application having all the agronutrients essential for plant growth is disclosed. The soil comprises a synthetic apatite fertilizer having sulfur, magnesium and micronutrients dispersed in a calcium phosphate matrix, a zeolite cation exchange medium saturated with a charge of potassium and nitrogen cations, and an optional pH buffer. Moisture dissolves the apatite and mobilizes the nutrient elements from the apatite matrix and the zeolite charge sites.

  18. Active synthetic soil

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W. (Inventor); Henninger, Donald L. (Inventor); Allen, Earl R. (Inventor); Golden, Dadigamuwage C. (Inventor)

    1995-01-01

    A synthetic soil/fertilizer for horticultural application having all the agronutrients essential for plant growth is disclosed. The soil comprises a synthetic apatite fertilizer having sulfur, magnesium, and micronutrients dispersed in a calcium phosphate matrix, a zeolite cation exchange medium saturated with a charge of potassium and nitrogen cations, and an optional pH buffer. Moisture dissolves the apatite and mobilizes the nutrient elements from the apatite matrix and the zeolite charge sites.

  19. Soil biotransformation of thiodiglycol, the hydrolysis product of mustard gas: understanding the factors governing remediation of mustard gas contaminated soil.

    PubMed

    Li, Hong; Muir, Robert; McFarlane, Neil R; Soilleux, Richard J; Yu, Xiaohong; Thompson, Ian P; Jackman, Simon A

    2013-02-01

    Thiodiglycol (TDG) is both the precursor for chemical synthesis of mustard gas and the product of mustard gas hydrolysis. TDG can also react with intermediates of mustard gas degradation to form more toxic and/or persistent aggregates, or reverse the pathway of mustard gas degradation. The persistence of TDG have been observed in soils and in the groundwater at sites contaminated by mustard gas 60 years ago. The biotransformation of TDG has been demonstrated in three soils not previously exposed to the chemical. TDG biotransformation occurred via the oxidative pathway with an optimum rate at pH 8.25. In contrast with bacteria isolated from historically contaminated soil, which could degrade TDG individually, a consortium of three bacterial strains isolated from the soil never contaminated by mustard gas was able to grow on TDG in minimal medium and in hydrolysate derived from an historical mustard gas bomb. Exposure to TDG had little impacts on the soil microbial physiology or on community structure. Therefore, the persistency of TDG in soils historically contaminated by mustard gas might be attributed to the toxicity of mustard gas to microorganisms and the impact to soil chemistry during the hydrolysis. TDG biodegradation may form part of a remediation strategy for mustard gas contaminated sites, and may be enhanced by pH adjustment and aeration.

  20. Constraining Gas Diffusivity-Soil Water Content Relationships in Forest Soils Using Surface Chamber Fluxes and Depth Profiles of Multiple Trace Gases

    NASA Astrophysics Data System (ADS)

    Dore, J. E.; Kaiser, K.; Seybold, E. C.; McGlynn, B. L.

    2012-12-01

    Forest soils are sources of carbon dioxide (CO2) to the atmosphere and can act as either sources or sinks of methane (CH4) and nitrous oxide (N2O), depending on redox conditions and other factors. Soil moisture is an important control on microbial activity, redox conditions and gas diffusivity. Direct chamber measurements of soil-air CO2 fluxes are facilitated by the availability of sensitive, portable infrared sensors; however, corresponding CH4 and N2O fluxes typically require the collection of time-course physical samples from the chamber with subsequent analyses by gas chromatography (GC). Vertical profiles of soil gas concentrations may also be used to derive CH4 and N2O fluxes by the gradient method; this method requires much less time and many fewer GC samples than the direct chamber method, but requires that effective soil gas diffusivities are known. In practice, soil gas diffusivity is often difficult to accurately estimate using a modeling approach. In our study, we apply both the chamber and gradient methods to estimate soil trace gas fluxes across a complex Rocky Mountain forested watershed in central Montana. We combine chamber flux measurements of CO2 (by infrared sensor) and CH4 and N2O (by GC) with co-located soil gas profiles to determine effective diffusivity in soil for each gas simultaneously, over-determining the diffusion equations and providing constraints on both the chamber and gradient methodologies. We then relate these soil gas diffusivities to soil type and volumetric water content in an effort to arrive at empirical parameterizations that may be used to estimate gas diffusivities across the watershed, thereby facilitating more accurate, frequent and widespread gradient-based measurements of trace gas fluxes across our study system. Our empirical approach to constraining soil gas diffusivity is well suited for trace gas flux studies over complex landscapes in general.

  1. Microbial mitigation of greenhouse gas emissions from landfill cover soils

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Woo

    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 proposed to stimulate methanotrophs, a group of bacteria that consume methane, in the cover soil to prevent fugitive methane emissions. Several factors, however, must be addressed to make such a biogenic removal mechanism effective. First, methanotrophic activity can be inhibited by nonmethane organic compounds (NMOCs) that are commonly found in landfill soil gas. Second, although methanotrophs can be easily stimulated with the addition of nitrogenous fertilizers, biogenic production of nitrous oxide with a GWP ˜296 times higher than that of carbon dioxide, is also stimulated. To consider these issues, two general areas of research were performed. First, a dimensionless number was developed based on Michaelis-Menten kinetics that describes the effects of the presence of multiple NMOCs on methanotrophic growth and survival. This model was validated via experimental measurements of methanotrophic growth in the presence of varying amounts of NMOCs. Second, the effects of nutrient amendments on methane oxidation and nitrous oxide production were examined by constructing soil microcosms using landfill cover soils. Here, it was shown that the addition of ammonium in the presence of phenylacetylene stimulated methane oxidation but inhibited nitrous oxide production. Furthermore, to understand the methanotrophic community structure and activity in response to these amendments, DNA microarray and transcript analyses were performed. The results indicated the predominance of Type II methanotrophs but that Type I methanotrophs responded more significantly to these amendments. Also, substantial activity

  2. Chaotic Behavior of Soil Radon Gas and Applications

    NASA Astrophysics Data System (ADS)

    Kamişlioğlu, Miraç; Külahci, Fatih

    2016-10-01

    The soil 222Rn concentration non-linear patterns are investigated by the application of various chaos methodologies based on 70 272 measurement data from the East Anatolian Fault Zone, which is one of the world's most active faults. Among these methodologies are Lyapunov exponent, surrogate data, rescaled range (R/S) analysis, Fourier spectrum, phase space reconstruction, mutual information, false nearest neighbors, and correlation dimension. The results indicate that the nonlinear dynamical approach is convenient for characterization and prediction of the 222Rn concentration dynamics, which are in turn usually used as an earthquake precursor. Behaviour of 222Rn gas is important in earthquake prediction researches.

  3. Soil disturbance increases soil microbial enzymatic activity in arid ecoregion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Functional diversity of the soil microbial community is commonly used in the assessment of soil health as it relates to the activity of soil microflora involved in carbon cycling. Soil microbes in different microenvironments will have varying responses to different substrates, thus catabolic fingerp...

  4. The determination of soil moisture by extraction and gas chromatography

    NASA Technical Reports Server (NTRS)

    Merek, E. L.; Carle, G. C.

    1974-01-01

    Soil moisture content was determined by extracting soil with methanol and subsequently analyzing the extract for water by gas chromatography. With air-dried mineral soils, this method gave slightly higher moisture content values than those obtained by the oven-dry method. Moisture content was determined quantitatively in soils to which various amounts of water had been added. The complete procedure, including extraction and analysis, requires less than one hour and gives results that closely compare to the oven-dry method.

  5. Utilization of soil gas monitoring to determine feasibility and effectiveness of in situ bioventing in hydrocarbon-contaminated soils

    SciTech Connect

    Frishmuth, R.A.; Ratz, J.W.; Hall, J.F.

    1996-12-31

    To determine the feasibility and effectiveness of in situ bioventing, careful monitoring of soil gas chemistry is essential. Prior to design of a bioventing system, initial soil gas surveys should be performed. Concentrations of three constituents, oxygen (O{sub 2}), carbon dioxide (CO{sub 2}), and total volatile hydrocarbons (TVH), are used in bioventing design. TVH are an indicator of contaminant distribution; O{sub 2} and CO{sub 2} are indicators of biodegradation activity. Analysis of soil gas data collected during pilot-scale testing is the primary design basis for full-scale remediation systems. Biodegradation rates determined from respiration tests are used to estimate the length of time that a system will have to operate to remediate the contamination. Air permeability of the soil, calculated from permeability testing, determines the number and spacing of air injection wells that will be required to ensure adequate oxygen influence through the entire contaminated area.

  6. Soil gas screening for chlorinated solvents at three contaminated karst sites in Tennessee

    USGS Publications Warehouse

    Wolfe, W.J.; Williams, S.D.

    2002-01-01

    Soil gas was sampled using active sampling techniques and passive collectors at three sites in Tennessee to evaluate the effectiveness of these techniques for locating chlorinated solvent sources and flowpaths in karst aquifers. Actively collected soil gas samples were analyzed in the field with a portable gas chromatograph, and the passive soil gas collectors were analyzed in the lab with gas chromatography/mass spectrometry. Results of the sampling indicate that the effectiveness of both techniques is highly dependent on the distribution of the contaminants in the subsurface, the geomorphic and hydrogeologic characteristics of the site, and, in one case, on seasonal conditions. Both active and passive techniques identified areas of elevated subsurface chlorinated solvent concentrations at a landfill site where contamination remains concentrated in the regolith. Neither technique detected chlorinated solvents known to be moving in the bedrock at a manufacturing site characterized by thick regolith and an absence of surficial karst features. Passive soil gas sampling had varied success detecting flowpaths for chloroform in the bedrock at a train derailment site characterized by shallow regolith and abundant surficial karst features. At the train derailment site, delineation of the contaminant flowpath through passive soil gas sampling was stronger and more detailed under Winter conditions than summer.

  7. A soil-column gas chromatography (SCGC) approach to explore the thermal desorption behavior of hydrocarbons from soils.

    PubMed

    Yu, Ying; Liu, Liang; Shao, Ziying; Ju, Tianyu; Sun, Bing; Benadda, Belkacem

    2016-01-01

    A soil-column gas chromatography approach was developed to simulate the mass transfer process of hydrocarbons between gas and soil during thermally enhanced soil vapor extraction (T-SVE). Four kinds of hydrocarbons-methylbenzene, n-hexane, n-decane, and n-tetradecane-were flowed by nitrogen gas. The retention factor k' and the tailing factor T f were calculated to reflect the desorption velocities of fast and slow desorption fractions, respectively. The results clearly indicated two different mechanisms on the thermal desorption behaviors of fast and slow desorption fractions. The desorption velocity of fast desorption fraction was an exponential function of the reciprocal of soil absolute temperature and inversely correlated with hydrocarbon's boiling point, whereas the desorption velocity of slow desorption fraction was an inverse proportional function of soil absolute temperature, and inversely proportional to the log K OW value of the hydrocarbons. The higher activation energy of adsorption was found on loamy soil with higher organic content. The increase of carrier gas flow rate led to a reduction in the apparent activation energy of adsorption of slow desorption fraction, and thus desorption efficiency was significantly enhanced. The obtained results are of practical interest for the design of high-efficiency T-SVE system and may be used to predict the remediation time.

  8. Soil degradation effect on biological activity in Mediterranean calcareous soils

    NASA Astrophysics Data System (ADS)

    Roca-Pérez, L.; Alcover-Sáez, S.; Mormeneo, S.; Boluda, R.

    2009-04-01

    Soil degradation processes include erosion, organic matter decline, compaction, salinization, landslides, contamination, sealing and biodiversity decline. In the Mediterranean region the climatological and lithological conditions, together with relief on the landscape and anthropological activity are responsible for increasing desertification process. It is therefore considered to be extreme importance to be able to measure soil degradation quantitatively. We studied soil characteristics, microbiological and biochemical parameters in different calcareous soil sequences from Valencia Community (Easter Spain), in an attempt to assess the suitability of the parameters measured to reflect the state of soil degradation and the possibility of using the parameters to assess microbiological decline and soil quality. For this purpose, forest, scrubland and agricultural soil in three soil sequences were sampled in different areas. Several sensors of the soil biochemistry and microbiology related with total organic carbon, microbial biomass carbon, soil respiration, microorganism number and enzyme activities were determined. The results show that, except microorganism number, these parameters are good indicators of a soil biological activity and soil quality. The best enzymatic activities to use like indicators were phosphatases, esterases, amino-peptidases. Thus, the enzymes test can be used as indicators of soil degradation when this degradation is related with organic matter losses. There was a statistically significant difference in cumulative O2 uptake and extracellular enzymes among the soils with different degree of degradation. We would like to thank Spanish government-MICINN for funding and support (MICINN, project CGL2006-09776).

  9. Greenhouse Gas Emissions from Brazilian Sugarcane Soils

    NASA Astrophysics Data System (ADS)

    Carmo, J.; Pitombo, L.; Cantarella, H.; Rosseto, R.; Andrade, C.; Martinelli, L.; Gava, G.; Vargas, V.; Sousa-Neto, E.; Zotelli, L.; Filoso, S.; Neto, A. E.

    2012-04-01

    Bioethanol from sugarcane is increasingly seen as a sustainable alternative energy source. Besides having high photosynthetic efficiency, sugarcane is a perennial tropical grass crop that can re-grow up to five or more years after being planted. Brazil is the largest producer of sugarcane in the world and management practices commonly used in the country lead to lower rates of inorganic N fertilizer application than sugarcane grown elsewhere, or in comparison to other feedstocks such as corn. Therefore, Brazilian sugarcane ethanol potentially promotes greenhouse gas savings. For that reason, several recent studies have attempted to assess emissions of greenhouse gases (GHG) during sugarcane production in the tropics. However, estimates have been mainly based on models due to a general lack of field data. In this study, we present data from in situ experiments on emission of three GHG (CO2, N2O, and CH4) in sugarcane fields in Brazil. Emissions are provided for sugarcane in different phases of the crop life cycle and under different management practices. Our results show that the use of nitrogen fertilizer in sugarcane crops resulted in an emission factor for N2O similar to those predicted by IPCC (1%), ranging from 0.59% in ratoon cane to 1.11% in plant cane. However, when vinasse was applied in addition to mineralN fertilizer, emissions of GHG increased in comparison to those from the use of mineral N fertilizer alone. Emissions increased significantly when experiments mimicked the accumulation of cane trash on the soil surface with 14 tons ha-1and 21 tons ha-1, which emission factor were 1.89% and 3.03%, respectively. This study is representative of Brazilian sugarcane systems under specific conditions for key factors affecting GHG emissions from soils. Nevertheless, the data provided will improve estimates of GHG from Brazilian sugarcane, and efforts to assess sugarcane ethanol sustainability and energy balance. Funding provided by the São Paulo Research

  10. Gas-geochemical condition and ecological functions of urban soils in areas with gas generating grounds

    NASA Astrophysics Data System (ADS)

    Mozharova, Nadezhda; Lebed-Sharlevich, Iana; Kulachkova, Svetlana

    2014-05-01

    Rapid urbanization and expansion of city borders lead to development of new areas, often following with relief changes, covering of gully-ravine systems and river beds with technogenic grounds containing construction and municipal waste. Decomposition of organic matter in these grounds is a source of methane and carbon dioxide. Intensive generation and accumulation of CO2 and CH4 into grounds may cause a fire and explosion risk for constructed objects. Gases emission to the atmosphere changes the global balance of GHGs and negatively influences on human health. The aim of this investigation is to study gas-geochemical condition and ecological functions of urban soils in areas with gas generating grounds. Studied areas are the gully-ravine systems or river beds, covered with technogenic grounds during land development. Stratigraphic columns of these grounds are 5-17 meters of man-made loamy material with inclusion of construction waste. Gas generating layer with increased content of organic matter, reductive conditions and high methanogenic activity (up to 1.0 ng*g-1*h-1) is situated at the certain depth. Maximum CH4 and CO2 concentrations in this layer reach dangerous values (2-10% and 11%, respectively) in the current standards. In case of disturbance of ground layer (e.g. well-drilling) methane is rapidly transferred by convective flux to atmosphere. The rate of CH4 emission reaches 100 mg*m-2*h-1 resulting in its atmospheric concentration growth by an order of magnitude compared with background. In normal occurrence of grounds methane gradually diffuses into the upper layers by pore space, consuming on different processes (e.g. formation of organic matter, nitrogen compounds or specific particles of magnetite), and emits to atmosphere. CH4 emission rate varies from 1 to 40 mg*m-2*h-1 increasing with depth of grounds. Carbon dioxide emission is about 100 mg*m-2*h-1. During soil formation on gas generating grounds bacterial oxidation of methane, one of the most

  11. Poly-use multi-level sampling system for soil-gas transport analysis in the vadose zone.

    PubMed

    Nauer, Philipp A; Chiri, Eleonora; Schroth, Martin H

    2013-10-01

    Soil-gas turnover is important in the global cycling of greenhouse gases. The analysis of soil-gas profiles provides quantitative information on below-ground turnover and fluxes. We developed a poly-use multi-level sampling system (PMLS) for soil-gas sampling, water-content and temperature measurement with high depth resolution and minimal soil disturbance. It is based on perforated access tubes (ATs) permanently installed in the soil. A multi-level sampler allows extraction of soil-gas samples from 20 locations within 1 m depth, while a capacitance probe is used to measure volumetric water contents. During idle times, the ATs are sealed and can be equipped with temperature sensors. Proof-of-concept experiments in a field lysimeter showed good agreement of soil-gas samples and water-content measurements compared with conventional techniques, while a successfully performed gas-tracer test demonstrated the feasibility of the PMLS to determine soil-gas diffusion coefficients in situ. A field application of the PMLS to quantify oxidation of atmospheric CH4 in a field lysimeter and in the forefield of a receding glacier yielded activity coefficients and soil-atmosphere fluxes well in agreement with previous studies. With numerous options for customization, the presented tool extends the methodological choices to investigate soil-gas transport in the vadose zone.

  12. Greenhouse gas emissions from soil under changing environmental conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This manuscript is the Guest Editors’ Introduction to a special issue on greenhouse gas emissions from agriculture. The papers were assembled following presentation at EuroSoil 2012. Exchange of greenhouse gases between soils and the atmosphere is a natural consequence of several ecosystem process...

  13. Characterization of Soil Samples of Enzyme Activity

    ERIC Educational Resources Information Center

    Freeland, P. W.

    1977-01-01

    Described are nine enzyme essays for distinguishing soil samples. Colorimetric methods are used to compare enzyme levels in soils from different sites. Each soil tested had its own spectrum of activity. Attention is drawn to applications of this technique in forensic science and in studies of soil fertility. (Author/AJ)

  14. Influence of Soil Moisture on Soil Gas Vapor Concentration for Vapor Intrusion

    PubMed Central

    Shen, Rui; Pennell, Kelly G.; Suuberg, Eric M.

    2013-01-01

    Abstract Mathematical models have been widely used in analyzing the effects of various environmental factors in the vapor intrusion process. Soil moisture content is one of the key factors determining the subsurface vapor concentration profile. This manuscript considers the effects of soil moisture profiles on the soil gas vapor concentration away from any surface capping by buildings or pavement. The “open field” soil gas vapor concentration profile is observed to be sensitive to the soil moisture distribution. The van Genuchten relations can be used for describing the soil moisture retention curve, and give results consistent with the results from a previous experimental study. Other modeling methods that account for soil moisture are evaluated. These modeling results are also compared with the measured subsurface concentration profiles in the U.S. EPA vapor intrusion database. PMID:24170970

  15. Influence of Soil Moisture on Soil Gas Vapor Concentration for Vapor Intrusion.

    PubMed

    Shen, Rui; Pennell, Kelly G; Suuberg, Eric M

    2013-10-01

    Mathematical models have been widely used in analyzing the effects of various environmental factors in the vapor intrusion process. Soil moisture content is one of the key factors determining the subsurface vapor concentration profile. This manuscript considers the effects of soil moisture profiles on the soil gas vapor concentration away from any surface capping by buildings or pavement. The "open field" soil gas vapor concentration profile is observed to be sensitive to the soil moisture distribution. The van Genuchten relations can be used for describing the soil moisture retention curve, and give results consistent with the results from a previous experimental study. Other modeling methods that account for soil moisture are evaluated. These modeling results are also compared with the measured subsurface concentration profiles in the U.S. EPA vapor intrusion database.

  16. Microbial Community Structure and Enzyme Activities in Semiarid Agricultural Soils

    NASA Astrophysics Data System (ADS)

    Acosta-Martinez, V. A.; Zobeck, T. M.; Gill, T. E.; Kennedy, A. C.

    2002-12-01

    The effect of agricultural management practices on the microbial community structure and enzyme activities of semiarid soils of different textures in the Southern High Plains of Texas were investigated. The soils (sandy clay loam, fine sandy loam and loam) were under continuous cotton (Gossypium hirsutum L.) or in rotations with peanut (Arachis hypogaea L.), sorghum (Sorghum bicolor L.) or wheat (Triticum aestivum L.), and had different water management (irrigated or dryland) and tillage (conservation or conventional). Microbial community structure was investigated using fatty acid methyl ester (FAME) analysis by gas chromatography and enzyme activities, involved in C, N, P and S cycling of soils, were measured (mg product released per kg soil per h). The activities of b-glucosidase, b-glucosaminidase, alkaline phosphatase, and arylsulfatase were significantly (P<0.05) increased in soils under cotton rotated with sorghum or wheat, and due to conservation tillage in comparison to continuous cotton under conventional tillage. Principal component analysis showed FAME profiles of these soils separated distinctly along PC1 (20 %) and PC2 (13 %) due to their differences in soil texture and management. No significant differences were detected in FAME profiles due to management practices for the same soils in this sampling period. Enzyme activities provide early indications of the benefits in microbial populations and activities and soil organic matter under crop rotations and conservation tillage in comparison to the typical practices in semiarid regions of continuous cotton and conventional tillage.

  17. Measuring radon-222 in soil gas with high spatial and temporal resolution.

    PubMed

    Huxtable, Darren; Read, David; Shaw, George

    2017-02-01

    In order to exploit (222)Rn as a naturally-occurring tracer in soils we need to sample and measure radon isotopes in soil gas with high spatial and temporal resolution, without disturbing in situ activity concentrations and fluxes. Minimisation of sample volume is key to improving the resolution with which soil gas can be sampled; an analytical method is then needed which can measure radon with appropriate detection limits and precision for soil gas tracer studies. We have designed a soil gas probe with minimal internal dead volume to allow us to sample soil gas volumes of 45 cm(3). Radon-222 is extracted from these samples into a mineral oil-based scintillation cocktail before counting on a conventional liquid scintillation counter. A detection limit of 320 Bq m(-3) (in soil gas) is achievable with a 1 h count. This could be further reduced but, in practice, is sufficient for our purpose since (222)Rn in soil gas typically ranges from 2000-50,000 Bq m(-3). The method is simple and provides several advantages over commonly used field-portable instruments, including smaller sample volumes, speed of deployment and reliability under field conditions. The major limitation is the need to count samples in a liquid scintillation counter within 2-3 days of collection, due to the short (3.824 day) radioactive half-life of (222)Rn. The method is not applicable to the very short-lived (55 s half-life) (220)Rn.

  18. Soil Management Effects on Gas Fluxes from an Organic Soil Agricultural System

    NASA Astrophysics Data System (ADS)

    Jennewein, S. P.; Bhadha, J. H.; Lang, T. A.; Singh, M.; Daroub, S. H.; McCray, M.

    2015-12-01

    The role of soil management on gas flux isn't well understood for Histosols of the Everglades Agricultural Area (EAA) of southern Florida. The region is responsible for roughly half of sugarcane (Saccharum spp. hybrids) production in the USA along with supplying winter vegetable crops to the eastern USA. Future productivity in the EAA is jeopardized by soil subsidence resulting from oxidation of organic matter. Establishing the role of tillage, water-table depth, nitrogen fertilizer, and soil depth on gas flux will help determine how effective various managements are on conserving soil. Ongoing lysimeter and field studies examined effects of management practices (water-table, tillage, and nitrogen fertilizer), and soil depth on, gas emission and microbial biomass. The trials were set in Belle Glade, FL, on Lauderhill muck (Lithic Haplosaprists). Results to be presented include soil microbial biomass and soil gas (CO2, CH4, and N2O) flux. This study provides insight into management effectiveness and agriculture sustainability on shallow muck soils of the EAA and will help farmers mitigate problems associated with soil subsidence and seasonally high water-tables.

  19. Soil gas radon concentrations measurements in terms of great soil groups.

    PubMed

    Içhedef, Mutlu; Saç, Müslim Murat; Camgöz, Berkay; Bolca, Mustafa; Harmanşah, Çoşkun

    2013-12-01

    In this study, soil gas radon concentrations were investigated according to locations, horizontal soil layers and great soil groups around Tuzla Fault, Seferihisar-İzmir. Great soil groups are a category that described the horizontal soil layers under soil classification system and distributions of radon concentration in the great soil groups are firstly determined by the present study. According to the obtained results, it has been showed that the radon concentrations in the Koluvial soil group are higher than the other soil groups in the region. Also significant differences on location in same great soil group were determined. The radon concentrations in the Koluvial soil groups were measured with respect to soil layers structures (A, B, C1, and C2). It has been observed that the values increase with depth of soil (C2>C1>B>A). The main reason may be due to the meteorological factors that have limited effect on radon escape from deep layers. Although fault lines pass thought the study area radon concentrations were varied location to location, layer to layer and great group to great group. The study shows that a detailed location description should be performed before soil radon measurements for earthquake predictions.

  20. NASA Soil Moisture Active Passive (SMAP) Applications

    NASA Astrophysics Data System (ADS)

    Orr, Barron; Moran, M. Susan; Escobar, Vanessa; Brown, Molly E.

    2014-05-01

    The launch of the NASA Soil Moisture Active Passive (SMAP) mission in 2014 will provide global soil moisture and freeze-thaw measurements at moderate resolution (9 km) with latency as short as 24 hours. The resolution, latency and global coverage of SMAP products will enable new applications in the fields of weather, climate, drought, flood, agricultural production, human health and national security. To prepare for launch, the SMAP mission has engaged more than 25 Early Adopters. Early Adopters are users who have a need for SMAP-like soil moisture or freeze-thaw data, and who agreed to apply their own resources to demonstrate the utility of SMAP data for their particular system or model. In turn, the SMAP mission agreed to provide Early Adopters with simulated SMAP data products and pre-launch calibration and validation data from SMAP field campaigns, modeling, and synergistic studies. The applied research underway by Early Adopters has provided fundamental knowledge of how SMAP data products can be scaled and integrated into users' policy, business and management activities to improve decision-making efforts. This presentation will cover SMAP applications including weather and climate forecasting, vehicle mobility estimation, quantification of greenhouse gas emissions, management of urban potable water supply, and prediction of crop yield. The presentation will end with a discussion of potential international applications with focus on the ESA/CEOS TIGER Initiative entitled "looking for water in Africa", the United Nations (UN) Convention to Combat Desertification (UNCCD) which carries a specific mandate focused on Africa, the UN Framework Convention on Climate Change (UNFCCC) which lists soil moisture as an Essential Climate Variable (ECV), and the UN Food and Agriculture Organization (FAO) which reported a food and nutrition crisis in the Sahel.

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

    PubMed

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

    2011-05-01

    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.

  2. Delineation of ground-water contamination using soil-gas analyses near Jackson, Tennessee

    USGS Publications Warehouse

    Lee, R.W.

    1991-01-01

    An investigation of the ground-water resources near Jackson, West Tennessee, was conducted during 1988-89. The study included determination of the occurrence of contaminants in the shallow aquifer using soil-gas analyses in the unsaturated zone. Between 1980 and 1988, an underground fuel-storage tank leaked about 3,000 gallons of unleaded fuel to the water table about 4 feet below land surface. A survey of soil gas using a gas chromatograph equipped with a photoionization detector showed concentrations of volatile organic compounds greater than IO, 000 parts per million near the leak These compounds were detected in an area about 240 feet long and 110 feet wide extending west from the point source. The chromatograms provided two distinct 'fingerprints' of volatile organic compounds. The first revealed the presence of benzene, toluene, andxylenes, which are constituents of unleaded fuel, in addition to other volatile compounds, in soil gas in the area near the leak The second did not reveal any detectable benzene, toluene, or xylenes in the soil-gas samples, but showed the presence of other unidentified volatile organic compounds in soil gas north of the storage tank. The distribution of total concentrations of volatile organic compounds in the unsaturated zone indicated that a second plume about 200 feet long and 90 feet wide was present about 100 feet north of the storage tank The second plume could have been the result of previous activities at this site during the 1950's or earlier. Activities at the site are believed to have included storage of solvents used at the nearby railyard and flushing of tanks containing tar onto a gravel-covered parking area. The delineation of these plumes has shown that soil-gas analyses can be a useful technique for identifying areas of contamination with volatile organic compounds in shallow water-table aquifers and may have broad applications in similar situations where the water table is relatively close to the surface.

  3. Quantitative assessment on soil enzyme activities of heavy metal contaminated soils with various soil properties.

    PubMed

    Xian, Yu; Wang, Meie; Chen, Weiping

    2015-11-01

    Soil enzyme activities are greatly influenced by soil properties and could be significant indicators of heavy metal toxicity in soil for bioavailability assessment. Two groups of experiments were conducted to determine the joint effects of heavy metals and soil properties on soil enzyme activities. Results showed that arylsulfatase was the most sensitive soil enzyme and could be used as an indicator to study the enzymatic toxicity of heavy metals under various soil properties. Soil organic matter (SOM) was the dominant factor affecting the activity of arylsulfatase in soil. A quantitative model was derived to predict the changes of arylsulfatase activity with SOM content. When the soil organic matter content was less than the critical point A (1.05% in our study), the arylsulfatase activity dropped rapidly. When the soil organic matter content was greater than the critical point A, the arylsulfatase activity gradually rose to higher levels showing that instead of harm the soil microbial activities were enhanced. The SOM content needs to be over the critical point B (2.42% in our study) to protect its microbial community from harm due to the severe Pb pollution (500mgkg(-1) in our study). The quantitative model revealed the pattern of variation of enzymatic toxicity due to heavy metals under various SOM contents. The applicability of the model under wider soil properties need to be tested. The model however may provide a methodological basis for ecological risk assessment of heavy metals in soil.

  4. Biochar and nitrogen fertilizer alters soil nitrogen dynamics and greenhouse gas fluxes from two temperate soils.

    PubMed

    Zheng, Jiyong; Stewart, Catherine E; Cotrufo, M Francesca

    2012-01-01

    Biochar (BC) application to agricultural soils could potentially sequester recalcitrant C, increase N retention, increase water holding capacity, and decrease greenhouse gas (GHG) emissions. Biochar addition to soils can alter soil N cycling and in some cases decrease extractable mineral N (NO and NH) and NO emissions. These benefits are not uniformly observed across varying soil types, N fertilization, and BC properties. To determine the effects of BC addition on N retention and GHG flux, we added two sizes (>250 and <250 µm) of oak-derived BC (10% w/w) to two soils (aridic Argiustoll and aquic Haplustoll) with and without N fertilizer and measured extractable NO and NH and GHG efflux (NO, CO, and CH) in a 123-d laboratory incubation. Biochar had no effect on NO, NH, or NO in the unfertilized treatments of either soil. Biochar decreased cumulative extractable NO in N fertilized treatments by 8% but had mixed effects on NH. Greenhouse gas efflux differed substantially between the two soils, but generally with N fertilizer BC addition decreased NO 3 to 60%, increased CO 10 to 21%, and increased CH emissions 5 to 72%. Soil pH and total treatment N (soil + fertilizer + BC) predicted soil NO flux well across these two different soils. Expressed as CO equivalents, BC significantly reduced GHG emissions only in the N-fertilized silt loam by decreasing NO flux. In unfertilized soils, CO was the dominant GHG component, and the direction of the flux was mediated by positive or negative BC effects on soil CO flux. On the basis of our data, the use of BC appears to be an effective management strategy to reduce N leaching and GHG emissions, particularly in neutral to acidic soils with high N content.

  5. Copper activity in soil solutions of calcareous soils.

    PubMed

    Ponizovsky, Alexander A; Allen, Herbert E; Ackerman, Amanda J

    2007-01-01

    Copper partitioning was studied in seven calcareous soils at moisture content corresponding to 1.2 times the field moisture content (soil water potential 7.84 J kg(-1)). Copper retention was accompanied by the release in soil solution of Ca(2+), Mg(2+), Na(+), and H(+), and the total amount of these cations released was 0.8 to 1.09 times the amount of Cu sorbed (mol(c):mol(c)). The relationships between Cu activity and pH, and the balance of cations in soils correspond with the surface precipitation of CuCO(3) as the main mechanism of Cu retention. The values of ion activity product of surface precipitate were close for all studied soils with the average log(IAP(CuCO(3)))=-15.51. The relationship between copper activity in soil solutions and soil properties is well fit by a regression relating pCu (-log copper ion activity) with soil pH, total Cu, and carbonate content.

  6. Plant diversity increases soil microbial activity and soil carbon storage.

    PubMed

    Lange, Markus; Eisenhauer, Nico; Sierra, Carlos A; Bessler, Holger; Engels, Christoph; Griffiths, Robert I; Mellado-Vázquez, Perla G; Malik, Ashish A; Roy, Jacques; Scheu, Stefan; Steinbeiss, Sibylle; Thomson, Bruce C; Trumbore, Susan E; Gleixner, Gerd

    2015-04-07

    Plant diversity strongly influences ecosystem functions and services, such as soil carbon storage. However, the mechanisms underlying the positive plant diversity effects on soil carbon storage are poorly understood. We explored this relationship using long-term data from a grassland biodiversity experiment (The Jena Experiment) and radiocarbon ((14)C) modelling. Here we show that higher plant diversity increases rhizosphere carbon inputs into the microbial community resulting in both increased microbial activity and carbon storage. Increases in soil carbon were related to the enhanced accumulation of recently fixed carbon in high-diversity plots, while plant diversity had less pronounced effects on the decomposition rate of existing carbon. The present study shows that elevated carbon storage at high plant diversity is a direct function of the soil microbial community, indicating that the increase in carbon storage is mainly limited by the integration of new carbon into soil and less by the decomposition of existing soil carbon.

  7. Evaluation-of soil enzyme activities as soil quality indicators in sludge-amended soils.

    PubMed

    Dindar, Efsun; Şağban, Fatma Olcay Topaç; Başkaya, Hüseyin Savaş

    2015-07-01

    Soil enzymatic activities are commonly used as biomarkers of soil quality. Several organic and inorganic compounds found in municipal wastewater sludges can possibly be used as fertilizers. Monitoring and evaluating the quality of sludge amended soils with enzyme activities accepted as a beneficial practice with respect to sustainable soil management. In the present study, variation of some enzyme activities (Alkaline phosphatase, dehydrogenase, urease and beta-glucosidase activities) in soils amended with municipal wastewater sludge at different application rates (50, 100 and 200 t ha(-1) dry sludge) was evaluated. Air dried sludge samples were applied to soil pots and sludge-soil mixtures were incubated during a period of three months at 28 degrees C. The results of the study showed that municipal wastewater sludge amendment apparently increased urease, dehydrogenase, alkaline phosphatase and P-glucosidase activities in soil by 48-70%, 14-47%, 33-66% and 9-14%, respectively. The maximum activity was generally observed in sludge amended soil with dose of 200 t ha(-1). Urease activity appeared to be a better indicator of soil enhancement with wastewater sludge, as its activity was more strongly increased by sludge amendment. Accordingly, urease activity is suggested to be soil quality indicator best suited for measuring existing conditions and potential changes in sludge-amended soil.

  8. Soil gas radon measurements in a region of the Bohemian Massif: investigations in the framework of an Austrian pilot study.

    PubMed

    Seidel, Claudia; Baumgartner, Andreas; Ringer, Wolfgang; Gräser, Joachim; Friedmann, Harry; Kaineder, Heribert; Maringer, Franz Josef

    2011-05-01

    Soil gas radon measurements are carried out in a pilot study in three municipalities in Upper Austria. The selected municipalities are characterised by a high radon potential. Sixty measuring sites--well distributed over the region and over the different geological areas--were selected. Additionally, the permeability of the soil was determined where the soil gas samples were taken and at various sites where soil samples were analysed by gamma spectrometry. Long-term soil-gas radon concentration measurements are carried out at several sites to study the long-term behaviour of radon activity concentration in soil, the influence of meteorological parameters and seasonal variations. The final goal of the project is to correlate the collected data with geological data and indoor radon concentration. First results of this ongoing study are presented and discussed.

  9. A CONCEPTUAL UNDERSTANDING OF LEAKAGE DURING SOIL-GAS SAMPLING

    EPA Science Inventory

    A heuristic model is developed to develop a conceptual understanding of leakage during soil-gas sampling. Leakage is shown to be simply a function of the permeability contrast between the formation and borehole and geometric factors. As the ratio of formation to borehole permea...

  10. Soil gas surveying at low-level radioactive waste sites

    SciTech Connect

    Crockett, A.B.; Moor, K.S.; Hull, L.C.

    1989-11-01

    Soil gas sampling is a useful screening technique for determining whether volatile organic compounds are present at low-level radioactive waste burial sites. The technique was used at several DOE sites during the DOE Environmental Survey to determine the presence and extent of volatile organic compound contamination. The advantages of the soil gas sampling are that near real time data can be obtained, no excavation is required, safety concerns are relatively minor, costs are relatively low, and large amounts of data can be obtained rapidly on the contaminants that may pose the greatest threat to groundwater resources. The disadvantages are that the data are difficult to interpret and relate to soil concentrations and environmental standards. This paper discusses the experiences of INEL sampling and analysis personnel, the advantages and disadvantages of the technique, and makes recommendations for improving the sampling and analytical procedures.

  11. Gas Transport Parameters for Landfill Cover Soils: Effects of Soil Compaction and Water Blockages

    NASA Astrophysics Data System (ADS)

    Wickramarachchi, P. N.; Hamamoto, S.; Kawamoto, K.; Nawagamuwa, U.; Komatsu, T.; Moldrup, P.

    2009-12-01

    Recently, landfill sites have been emerging in greenhouse warming scenarios as a significant source of atmospheric CH4. landfill management strategies have mainly addressed the problem of preventing groundwater contamination and reduction of leachate generation. Being one of the largest source of anthropogenic CH4 emission , the final cover system should also be designed for minimizing the biogas migration into the atmosphere or the areas surrounding the landfill. Compared to the intensive research efforts on hydraulic performances of landfill final cover soil , there are few studies about gas transport characteristics of landfill cover soils. Therefore, the effects of soil physical properties such as bulk density (i.e., compaction level), soil particle size and water blockage effects on the gas exchange in t highly compacted final cover soil are largely unknown. The gas exchange through the final cover soils is controlled by advective and diffusive gas transport. Air permeability (ka) governs the advective gas transport while the soil-gas diffusion coefficient (Dp) governs diffusive gas transport . In this study, the effects of compaction level and water blockage effects on ka and Dp for two landfill final cover soils were investigated. The disturbed soil samples were taken from landfill final covers in Japan and Sri Lanka. A compaction tests were performed for the soil samples with two different size fractions (< 35 mm and < 2.0 mm). In the compaction tests at field water content , the soil samples were repacked into soil cores (i.d. 15-cm, length 12-cm) at two different compaction levels (2700 kN/m2 and 600 kN/m2). After the compaction tests, ka and Dp were measured and then samples were saturated and subsequently drained at different soil-water matric potential (pF; pF equals to log(-ɛ) where ɛ is soil-water matric potential in cm H2O) of 1.5, 2.0, 3.0, 4.1, and with air-dried (pF 6.0) and oven-dried (pF 6.9) conditions. Results showed that measured Dp values

  12. Testing CO2 Sequestration in an Alkaline Soil Treated with Flue Gas Desulfurization Gypsum (FGDG)

    NASA Astrophysics Data System (ADS)

    Han, Y.; Tokunaga, T. K.

    2012-12-01

    Identifying effective and economical methods for increasing carbon storage in soils is of interest for reducing soil CO2 fluxes to the atmosphere in order to partially offset anthropogenic CO2 contributions to climate change This study investigates an alternative strategy for increasing carbon retention in soils by accelerating calcite (CaCO3) precipitation and promoting soil organic carbon (SOC) complexation on mineral surfaces. The addition of calcium ion to soils with pH > 8, often found in arid and semi-arid regions, may accelerate the slow process of calcite precipitation. Increased ionic strength from addition of a soluble Ca source also suppresses microbial activity which oxidizes SOC to gaseous CO2. Through obtaining C mass balances in soil profiles, this study is quantifying the efficiency of gypsum amendments for mitigating C losses to the atmosphere. The objective of this study is to identify conditions in which inorganic and organic C sequestration is practical in semi-arid and arid soils by gypsum treatment. As an inexpensive calcium source, we proposed to use flue gas desulfurization gypsum (FGDG), a byproduct of fossil fuel burning electric power plants. To test the hypothesis, laboratory column experiments have been conducted in calcite-buffered soil with addition of gypsum and FGDG. The results of several months of column monitoring are demonstrating that gypsum-treated soil have lowered amounts of soil organic carbon loss and increased inorganic carbon (calcite) production. The excess generation of FGDG relative to industrial and agricultural needs, FGDG, is currently regarded as waste. Thus application of FGDG application in some soils may be an effective and economical means for fixing CO2 in soil organic and inorganic carbon forms.Soil carbon cycle, with proposed increased C retention by calcite precipitation and by SOC binding onto soil mineral surfaces, with both processes driven by calcium released from gypsum dissolution.

  13. Composting of biochars improves their sorption properties, retains nutrients during composting and affects greenhouse gas emissions after soil application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar application to soils has been suggested to elevate nutrient sorption, improve soil fertility and reduce net greenhouse gas (GHG) emissions. We examined the impact of composting biochar together with a biologically active substrate (i.e., livestock manure-straw mixture). We hypothesized that ...

  14. Using soil oxygen sensors to inform understanding of soil greenhouse gas dynamics

    NASA Astrophysics Data System (ADS)

    Jarecke, K. M.; Loecke, T.; Burgin, A. J.; Franz, T. E.; Rubol, S.

    2015-12-01

    Hot spots and hot moments of greenhouse gas (GHG) fluxes can contribute significantly to overall GHG budgets. Hot spots and hot moments occur when dynamic soil hydrology triggers important shifts in soil biogeochemical and physical processes that control GHG emissions. Soil oxygen (O2), a direct control on biogenic GHG production (i.e., nitrous oxide-N2O, carbon dioxide-CO2 and methane-CH4), may serve as both an important proxy for determining sudden shifts in subsurface biogenic GHG production, as well as the physical transport of soil GHG to the atmosphere. Recent technological advancements offer opportunities to link in-situ, near-continuous measurements of soil O2 concentration to soil biogeochemical processes and soil gas transport. Using high frequency data, this study asked: Do soil O2 dynamics correspond to changes in soil GHG concentrations and GHG surface fluxes? We addressed this question using precipitation event-based and weekly sampling (19 months in duration) data sets from a restored riparian wetland in Ohio, USA. During and after precipitation events, changes in subsurface (10 and 20 cm) CO2 and N2O concentrations were inversely related to short-term (< 48 h) changes in soil O2 concentrations. Subsurface CH4 concentrations changes during precipitation events, however, did not change in response to soil O2 dynamics. Changing subsurface GHG concentrations did not necessarily translate into altered surface (soil to atmosphere) GHG fluxes; soil O2 dynamics at 10 cm did not correspond with changes in surface N2O and CH4 fluxes. However, changes in soil O2 concentration at 10 cm had a significant positive linear relationship with change in surface CO2­ flux. We used a random forest approach to identify the soil sensor data (O2, temperature, moisture) which contribute the most to predicting weekly GHG fluxes. Our study suggests that monitoring near-continuous soil O2 concentration under dynamic soil hydrology may lead to greater understanding of GHG

  15. Manipulations of soil microbiota for C sequestration and mitigation of greenhouse gas emissions in managed systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil microbes dominate processes that regulate soil trace gas emissions and soil C and N dynamics. Intensive management in agroecosystems provides unique opportunities to assess the effectiveness of microbial manipulations to enhance soil C retention and reduce trace gas emissions. While reduced til...

  16. A New Screening Method for Methane in Soil Gas Using Existing Groundwater Monitoring Wells

    EPA Science Inventory

    Methane in soil gas may have undesirable consequences. The soil gas may be able to form a flammable mixture with air and present an explosion hazard. Aerobic biodegradation of the methane in soil gas may consume oxygen that would otherwise be available for biodegradation of gasol...

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

    USGS Publications Warehouse

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

    2011-01-01

    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

  18. Coastal vegetation invasion increases greenhouse gas emission from wetland soils but also increases soil carbon accumulation.

    PubMed

    Chen, Yaping; Chen, Guangcheng; Ye, Yong

    2015-09-01

    Soil properties and soil-atmosphere fluxes of CO2, CH4 and N2O from four coastal wetlands were studied throughout the year, namely, native Kandelia obovata mangrove forest vs. exotic Sonneratia apetala mangrove forest, and native Cyperus malaccensis salt marsh vs. exotic Spartina alterniflora salt marsh. Soils of the four wetlands were all net sources of greenhouse gases while Sonneratia forest contributed the most with a total soil-atmosphere CO2-equivalent flux of 137.27 mg CO2 m(-2) h(-1), which is 69.23%, 99.75% and 44.56% higher than that of Kandelia, Cyperus and Spartina, respectively. The high underground biomass and distinctive root structure of Sonneratia might be responsible for its high greenhouse gas emission from the soil. Soils in Spartina marsh emitted the second largest amount of total greenhouse gases but it ranked first in emitting trace greenhouse gases. Annual average CH4 and N2O fluxes from Spartina soil were 13.77 and 1.14 μmol m(-2) h(-1), respectively, which are 2.08 and 1.46 times that of Kandelia, 1.03 and 1.15 times of Sonneratia, and 1.74 and 1.02 times of Cyperus, respectively. Spartina has longer growing season and higher productivity than native marshes which might increase greenhouse gas emission in cold seasons. Exotic wetland soils had higher carbon stock as compared to their respective native counterparts but their carbon stocks were offset by a larger proportion because of their higher greenhouse gas emissions. Annual total soil-atmosphere fluxes of greenhouse gases reduced soil carbon burial benefits by 8.1%, 9.5%, 6.4% and 7.2% for Kandelia, Sonneratia, Cyperus and Spartina, respectively, which narrowed down the gaps in net soil carbon stock between native and exotic wetlands. The results indicated that the invasion of exotic wetland plants might convert local coastal soils into a considerable atmospheric source of greenhouse gases although they at the same time increase soil carbon accumulation.

  19. Coupling above and below ground gas measurements to understand greenhouse gas production in the soil profile

    NASA Astrophysics Data System (ADS)

    Nickerson, Nick; Creelman, Chance

    2016-04-01

    Natural and anthropogenic changes in climate have the potential to significantly affect the Earth's natural greenhouse gas balances. To understand how these climatic changes will manifest in a complex biological, chemical and physical system, a process-based understanding of the production and consumption of greenhouse gases in soils is critical. Commonly, both chamber methods and gradient-based approaches are used to estimate greenhouse gas flux from the soil to the atmosphere. Each approach offers benefits, but not surprisingly, comes with a list of drawbacks. Chambers are easily deployed on the surface without significant disturbance to the soil, and can be easily spatially replicated. However the high costs of automated chamber systems and the inability to partition fluxes by depth are potential downfalls. The gradient method requires a good deal of disturbance for installation, however it also offers users spatiotemporally resolved flux estimates at a reasonable price point. Researchers widely recognize that the main drawback of the gradient approach is the requirement to estimate diffusivity using empirical models based on studies of specific soils or soil types. These diffusivity estimates can often be off by several orders of magnitude, yielding poor flux estimates. Employing chamber and gradient methods in unison allows for in-situ estimation of the diffusion coefficient, and therefore improves gradient-based estimates of flux. A dual-method approach yields more robust information on the temporal dynamics and depth distribution of greenhouse gas production and consumption in the soil profile. Here we present a mathematical optimization framework that allows these complimentary measurement techniques to yield more robust information than a single technique alone. We then focus on how it can be used to improve the process-based understanding of greenhouse gas production in the soil profile.

  20. An in situ method for real-time monitoring of soil gas diffusivity

    NASA Astrophysics Data System (ADS)

    Laemmel, Thomas; Maier, Martin; Schack-Kirchner, Helmer; Lang, Friederike

    2016-04-01

    Soil aeration is an important factor for the biogeochemistry of soils. Generally, gas exchange between soil and atmosphere is assumed to be governed by molecular diffusion and by this way fluxes can be calculated using by Fick's Law. The soil gas diffusion coefficient DS represents the proportional factor between the gas flux and the gas concentration gradient in the soil and reflects the ability of the soil to "transport passively" gas through the soil. One common way to determine DS is taking core samples in the field and measuring DS in the lab. Unfortunately this method is destructive and laborious and it can only reflect a small fraction of the whole soil. As a consequence, uncertainty about the resulting effective diffusivity on the profile scale, i.e. the real aeration status remains. We developed a method to measure and monitor DS in situ. The set-up consists of a custom made gas sampling device, the continuous injection of an inert tracer gas and inverse gas transport modelling in the soil. The gas sampling device has seven sampling depths (from 0 to -43 cm of depth) and can be easily installed into vertical holes drilled by an auger, which allows for fast installation of the system. Helium (He) as inert tracer gas was injected continuously at the lower end of the device. The resulting steady state distribution of He was used to deduce the DS depth distribution of the soil. For Finite Element Modeling of the gas-sampling-device/soil system the program COMSOL was used. We tested our new method both in the lab and in a field study and compared the results with a reference lab method using soil cores. DS profiles obtained by our in-situ method were consistent with DS profiles determined based on soil core analyses. Soil gas profiles could be measured with a temporal resolution of 30 minutes. During the field study, there was an important rain event and we could monitor the decrease in soil gas diffusivity in the top soil due to water infiltration. The effect

  1. Greenhouse gas fluxes from agricultural soils of Kenya and Tanzania

    NASA Astrophysics Data System (ADS)

    Rosenstock, Todd S.; Mpanda, Mathew; Pelster, David E.; Butterbach-Bahl, Klaus; Rufino, Mariana C.; Thiong'o, Margaret; Mutuo, Paul; Abwanda, Sheila; Rioux, Janie; Kimaro, Anthony A.; Neufeldt, Henry

    2016-06-01

    Knowledge of greenhouse gas (GHG) fluxes in soils is a prerequisite to constrain national, continental, and global GHG budgets. However, data characterizing fluxes from agricultural soils of Africa are markedly limited. We measured carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) fluxes at 10 farmer-managed sites of six crop types for 1 year in Kenya and Tanzania using static chambers and gas chromatography. Cumulative emissions ranged between 3.5-15.9 Mg CO2-C ha-1 yr-1, 0.4-3.9 kg N2O-N ha-1 yr-1, and -1.2-10.1 kg CH4-C ha-1 yr-1, depending on crop type, environmental conditions, and management. Manure inputs increased CO2 (p = 0.03), but not N2O or CH4, emissions. Soil cultivation had no discernable effect on emissions of any of the three gases. Fluxes of CO2 and N2O were 54-208% greater (p < 0.05) during the wet versus the dry seasons for some, but not all, crop types. The heterogeneity and seasonality of fluxes suggest that the available data describing soil fluxes in Africa, based on measurements of limited duration of only a few crop types and agroecological zones, are inadequate to use as a basis for estimating the impact of agricultural soils on GHG budgets. A targeted effort to understand the magnitude and mechanisms underlying African agricultural soil fluxes is necessary to accurately estimate the influence of this source on the global climate system and for determining mitigation strategies.

  2. [Effects of Hg on soil enzyme activity].

    PubMed

    Yang, Chun-Lu; Sun, Tie-Heng; He, Wen-Xiang; Chen, Su

    2007-03-01

    With simulation test, this paper studied the effects of Hg on the activities of urease, invertase and neutral phosphotase in four soils. The results showed that Hg inhibited soil urease and invertase activities markedly, but its inhibitory effect differed with test soils. There was a significant logarithmic correlation between the concentration of HgCl2 and the activities of these two enzymes (P < 0.05). In test soils, the ED50 of urease activity was 87.99, 5.47, 24.05 and 19.88 mg x kg(-1), and that of invertase activity was 76.68, 727.49, 236.52 and 316.59 mg x kg(-1), respectively. Urease was more sensitive than invertase to Hg contamination, while organic matter had a protective effect on soil enzymes. Soil neutral phosphatase was not sensitive to Hg contamination, except that it was significantly activated by Hg in the meadow brown soil applied with plenty of organic fertilizer.

  3. Metatranscriptomic census of active protists in soils

    PubMed Central

    Geisen, Stefan; Tveit, Alexander T; Clark, Ian M; Richter, Andreas; Svenning, Mette M; Bonkowski, Michael; Urich, Tim

    2015-01-01

    The high numbers and diversity of protists in soil systems have long been presumed, but their true diversity and community composition have remained largely concealed. Traditional cultivation-based methods miss a majority of taxa, whereas molecular barcoding approaches employing PCR introduce significant biases in reported community composition of soil protists. Here, we applied a metatranscriptomic approach to assess the protist community in 12 mineral and organic soil samples from different vegetation types and climatic zones using small subunit ribosomal RNA transcripts as marker. We detected a broad diversity of soil protists spanning across all known eukaryotic supergroups and revealed a strikingly different community composition than shown before. Protist communities differed strongly between sites, with Rhizaria and Amoebozoa dominating in forest and grassland soils, while Alveolata were most abundant in peat soils. The Amoebozoa were comprised of Tubulinea, followed with decreasing abundance by Discosea, Variosea and Mycetozoa. Transcripts of Oomycetes, Apicomplexa and Ichthyosporea suggest soil as reservoir of parasitic protist taxa. Further, Foraminifera and Choanoflagellida were ubiquitously detected, showing that these typically marine and freshwater protists are autochthonous members of the soil microbiota. To the best of our knowledge, this metatranscriptomic study provides the most comprehensive picture of active protist communities in soils to date, which is essential to target the ecological roles of protists in the complex soil system. PMID:25822483

  4. Nitrogen transformations and greenhouse gas emissions from a riparian wetland soil: an undisturbed soil column study.

    PubMed

    Muñoz-Leoz, Borja; Antigüedad, Iñaki; Garbisu, Carlos; Ruiz-Romera, Estilita

    2011-01-15

    Riparian wetlands bordering intensively managed agricultural fields can act as biological filters that retain and transform agrochemicals such as nitrate and pesticides. Nitrate removal in wetlands has usually been attributed to denitrification processes which in turn imply the production of greenhouse gases (CO(2) and N(2)O). Denitrification processes were studied in the Salburua wetland (northern Spain) by using undisturbed soil columns which were subsequently divided into three sections corresponding to A-, Bg- and B2g-soil horizons. Soil horizons were subjected to leaching with a 200 mg NO₃⁻L⁻¹ solution (rate: 90 mL day⁻¹) for 125 days at two different temperatures (10 and 20°C), using a new experimental design for leaching assays which enabled not only to evaluate leachate composition but also to measure gas emissions during the leaching process. Column leachate samples were analyzed for NO₃⁻concentration, NH(4)(+) concentration, and dissolved organic carbon. Emissions of greenhouse gases (CO₂ and N₂O) were determined in the undisturbed soil columns. The A horizon at 20°C showed the highest rates of NO₃⁻ removal (1.56 mg N-NO₃⁻kg⁻¹ DW soil day⁻¹) and CO₂ and N₂O production (5.89 mg CO₂ kg⁻¹ DW soil day⁻¹ and 55.71 μg N-N₂O kg⁻¹ DW soil day⁻¹). For the Salburua wetland riparian soil, we estimated a potential nitrate removal capacity of 1012 kg N-NO₃⁻ha⁻¹ year⁻¹, and potential greenhouse gas emissions of 5620 kg CO₂ ha⁻¹ year⁻¹ and 240 kg N-N₂O ha⁻¹ year⁻¹.

  5. One year continuous soil gas monitoring above an EGR test site

    NASA Astrophysics Data System (ADS)

    Furche, Markus; Schlömer, Stefan; Faber, Eckhard; Dumke, Ingolf

    2010-05-01

    Setup and first results of an ongoing research activity are presented, which is funded by the German Geotechnologien program within in the joint project CLEAN (CO2 Large Scale Enhanced Gas Recovery in the Altmark Natural Gas Field). The task is to establish several soil gas monitoring stations above a partly exhausted gas field in the Altmark which will be used for an enhanced gas recovery (EGR) test by injecting CO2 into the reservoir. The aim is to optimize the monitoring technique including automatic data transfer and data exploitation and to understand mechanisms of natural variations of soil gas concentrations in the specific area. Furthermore the suitability of these measurements as a contribution to leakage detection shall be evaluated. A network of 13 gauging stations for the measurement of CO2 is working continuously for about one year. They are spread over an area of 8 x 3 km and are situated in direct vicinity of existing deep boreholes as the most likely locations for possible leakage. In addition one station is placed far outside the gasfield as a reference point. The technique applied to measure soil gas concentrations uses a gas stream circulating in a tube going down a shallow borehole where the circulating gas is in contact with the soil gas phase via a gas permeable membrane. Above surface, moisture is removed from the gas stream before it reaches several gas sensors for CO2. Besides these, several other parameters are determined as well, e.g. soil moisture and soil temperature, water level, gas flow and gas moisture. In addition a meteorological station gives information about precipitation, air humidity, temperature and pressure, global radiation, wind direction and velocity in the area. Data are continuously collected by dataloggers at each station (5 minutes interval), transferred via GSM routers to the BGR server in Hannover and are stored in a specially designed database. The database does not only contain the measurements but also

  6. Iron Oxides from Volcanic Soils as Potential Catalysts in the Water Gas Shift Reaction

    SciTech Connect

    Pizarro, C.; Escudey, M.; Moya, S.A.; Fabris, J.D.

    2005-04-26

    This study was focused on changes of the iron oxide mineralogy with temperature of two Chilean soils (Andisol and Ultisol) derived from volcanic materials and their use as iron-based catalysts in the water gas shift reaction (WGSR). Ultisol materials produced about twice as much hydrogen than did those from Andisol upon WGSR, but in both cases hydrogen yielding increased as the heating temperature of the soil materials increased from 124 deg. C to 500 deg. C. The room temperature Moessbauer spectra showed an increase of the relative proportion of the magnetically ordered components as temperature increased. Higher heating temperature produced a negative effect on the catalytic activity, whereas the organic matter destruction led to a positive effect, due to an increasing exposition of the iron oxide surfaces; heating the soil sample at 600 deg. C induced changes on the iron oxide mineralogy with a significant decrease of the catalytic activity.

  7. Red soil as a regenerable sorbent for high temperature removal of hydrogen sulfide from coal gas.

    PubMed

    Ko, Tzu-Hsing; Chu, Hsin; Lin, Hsiao-Ping; Peng, Ching-Yu

    2006-08-25

    In this study, hydrogen sulfide (H(2)S) was removed from coal gas by red soil under high temperature in a fixed-bed reactor. Red soil powders were collected from the northern, center and southern of Taiwan. They were characterized by XRPD, porosity analysis and DCB chemical analysis. Results show that the greater sulfur content of LP red soils is attributed to the higher free iron oxides and suitable sulfidation temperature is around 773K. High temperature has a negative effect for use red soil as a desulfurization sorbent due to thermodynamic limitation in a reduction atmosphere. During 10 cycles of regeneration, after the first cycle the red soil remained stable with a breakthrough time between 31 and 36 min. Hydrogen adversely affects sulfidation reaction, whereas CO exhibits a positive effect due to a water-shift reaction. COS was formed during the sulfidation stage and this was attributed to the reaction of H(2)S and CO. Results of XRPD indicated that, hematite is the dominant active species in fresh red soil and iron sulfide (FeS) is a product of the reaction between hematite and hydrogen sulfide in red soils. The spinel phase FeAl(2)O(4) was found during regeneration, moreover, the amount of free iron oxides decreased after regeneration indicating the some of the free iron oxide formed a spinel phase, further reducting the overall desulfurization efficiency.

  8. Reactive Gas transport in soil: Kinetics versus Local Equilibrium Approach

    NASA Astrophysics Data System (ADS)

    Geistlinger, Helmut; Jia, Ruijan

    2010-05-01

    Gas transport through the unsaturated soil zone was studied using an analytical solution of the gas transport model that is mathematically equivalent to the Two-Region model. The gas transport model includes diffusive and convective gas fluxes, interphase mass transfer between the gas and water phase, and biodegradation. The influence of non-equilibrium phenomena, spatially variable initial conditions, and transient boundary conditions are studied. The objective of this paper is to compare the kinetic approach for interphase mass transfer with the standard local equilibrium approach and to find conditions and time-scales under which the local equilibrium approach is justified. The time-scale of investigation was limited to the day-scale, because this is the relevant scale for understanding gas emission from the soil zone with transient water saturation. For the first time a generalized mass transfer coefficient is proposed that justifies the often used steady-state Thin-Film mass transfer coefficient for small and medium water-saturated aggregates of about 10 mm. The main conclusion from this study is that non-equilibrium mass transfer depends strongly on the temporal and small-scale spatial distribution of water within the unsaturated soil zone. For regions with low water saturation and small water-saturated aggregates (radius about 1 mm) the local equilibrium approach can be used as a first approximation for diffusive gas transport. For higher water saturation and medium radii of water-saturated aggregates (radius about 10 mm) and for convective gas transport, the non-equilibrium effect becomes more and more important if the hydraulic residence time and the Damköhler number decrease. Relative errors can range up to 100% and more. While for medium radii the local equilibrium approach describes the main features both of the spatial concentration profile and the time-dependence of the emission rate, it fails completely for larger aggregates (radius about 100 mm

  9. The microbial communities and potential greenhouse gas production in boreal acid sulphate, non-acid sulphate, and reedy sulphidic soils.

    PubMed

    Šimek, Miloslav; Virtanen, Seija; Simojoki, Asko; Chroňáková, Alica; Elhottová, Dana; Krištůfek, Václav; Yli-Halla, Markku

    2014-01-01

    Acid sulphate (AS) soils along the Baltic coasts contain significant amounts of organic carbon and nitrogen in their subsoils. The abundance, composition, and activity of microbial communities throughout the AS soil profile were analysed. The data from a drained AS soil were compared with those from a drained non-AS soil and a pristine wetland soil from the same region. Moreover, the potential production of methane, carbon dioxide, and nitrous oxide from the soils was determined under laboratory conditions. Direct microscopic counting, glucose-induced respiration (GIR), whole cell hybridisation, and extended phospholipid fatty acid (PLFA) analysis confirmed the presence of abundant microbial communities in the topsoil and also in the deepest Cg2 horizon of the AS soil. The patterns of microbial counts, biomass and activity in the profile of the AS soil and partly also in the non-AS soil therefore differed from the general tendency of gradual decreases in soil profiles. High respiration in the deepest Cg2 horizon of the AS soil (5.66 μg Cg(-1)h(-1), as compared to 2.71 μg Cg(-1)h(-1) in a top Ap horizon) is unusual but reasonable given the large amount of organic carbon in this horizon. Nitrous oxide production peaked in the BCgc horizon of the AS and in the BC horizon of the non-AS soil, but the peak value was ten-fold higher in the AS soil than in the non-AS soil (82.3 vs. 8.6 ng Ng(-1)d(-1)). The data suggest that boreal AS soils on the Baltic coast contain high microbial abundance and activity. This, together with the abundant carbon and total and mineral nitrogen in the deep layers of AS soils, may result in substantial gas production. Consequently, high GHG emissions could occur, for example, when the generally high water table is lowered because of arable farming.

  10. The Influence of Extreme Water Pulses on Greenhouse Gas Emissions from Soils

    NASA Astrophysics Data System (ADS)

    Petrakis, S.; Vargas, R.; Seyfferth, A.; Kan, J.; Inamdar, S. P.

    2015-12-01

    Anthropogenic activity increasing the amount of radiatively active gases, or Greenhouse Gases (GHGs) in the earth's atmosphere has led to shifts in weather patterns. Climate models predict the occurrence of large storms may increase in frequency and intensity in the mid-Atlantic region. Knowing that extreme precipitation events are rare, testing the influence of large water pulses across different soil types within an ecosystem is challenging. Large additions of water could promote or inhibit microbial activity, and change soil chemistry within a few days. Rapid changes in soil moisture lead to shifts in the behavior of soils as either sinks or sources of several GHGs (i.e., CO2, CH4 and N2O). Unfortunately, it is still unclear how rewetting events could impact the magnitude of GHG fluxes and how changing soil chemical parameters influence these responses. An experiment was designed to test the influence of extreme repeated water pulses on GHG fluxes from four different soils, representing key topographic locations within a watershed in the Piedmont region (i.e., forested upland, forested lowland, creek, wetland). Intact soil cores from these four soil types were kept under constant temperature (22oC) and we measured their responses to extreme water pulses. We continuously (hourly resolution) measured CO2, CH4 and N2O fluxes using a LI-8100A (Licor, Lincoln, NE) multiplexed system coupled to a Picarro G2508 (Picarro, Santa Clara, CA). Furthermore, we used a rhizolysimeter for porewater extraction to measure pH, redox, and water chemistry throughout the experiment. We hypothesized that repeated extreme water pulses would result in non-linear responses of GHG flux magnitudes and dynamics, and these dynamics would relate to changes in soil chemistry. We found that soil moisture alone could not explain the dynamics of GHG fluxes, but these extreme water pulses influenced the overall temporal patterns of all GHGs across all soil types. We also examined the 100 year

  11. Evaluation of soil gas sampling and analysis techniques at a former petrochemical plant site.

    PubMed

    Hers, I; Li, L; Hannam, S

    2004-07-01

    Methods for soil gas sampling and analysis are evaluated as part of a research study on soil vapour intrusion into buildings, conducted at a former petro-chemical plant site ("Chatterton site"). The evaluation process was designed to provide information on reliability and selection of appropriate methods for soil gas sampling and analysis, and was based on a literature review of data and methods, and experiments completed as part of the research study. The broader context of this work is that soil gas characterization is increasingly being used for input into risk assessment of contaminated sites, particularly when evaluating the potential intrusion of soil vapour into buildings. There are only a limited number of research studies and protocols addressing soil gas sampling and analysis. There is significant variability in soil gas probe design and sample collection and analysis methods used by practitioners. The experimental studies conducted to evaluate soil gas methods address the permeation or leakage of gases from Tedlar bags, time-dependent sorption of volatile organic compound (VOC)-vapours onto probe surfaces and sampling devices, and analytical and quality control issues for light gas and VOC analyses. Through this work, common techniques for soil gas collection and analysis are described together with implications for data quality arising from the different methods used. Some of the potential pitfalls that can affect soil gas testing are identified, and recommendations and guidance for improved protocols are provided.

  12. Estimating methane gas production in peat soils of the Florida Everglades using hydrogeophysical methods

    NASA Astrophysics Data System (ADS)

    Wright, William; Comas, Xavier

    2016-04-01

    The spatial and temporal variability in production and release of greenhouse gases (such as methane) in peat soils remains uncertain, particularly for low-latitude peatlands like the Everglades. Ground penetrating radar (GPR) is a hydrogeophysical tool that has been successfully used in the last decade to noninvasively investigate carbon dynamics in peat soils; however, application in subtropical systems is almost non-existent. This study is based on four field sites in the Florida Everglades, where changes in gas content within the soil are monitored using time-lapse GPR measurements and gas releases are monitored using gas traps. A weekly methane gas production rate is estimated using a mass balance approach, considering gas content estimated from GPR, gas release from gas traps and incorporating rates of diffusion, and methanotrophic consumption from previous studies. Resulting production rates range between 0.02 and 0.47 g CH4 m-2 d-1, falling within the range reported in literature. This study shows the potential of combining GPR with gas traps to monitor gas dynamics in peat soils of the Everglades and estimate methane gas production. We also show the enhanced ability of certain peat soils to store gas when compared to others, suggesting that physical properties control biogenic gas storage in the Everglades peat soils. Better understanding biogenic methane gas dynamics in peat soils has implications regarding the role of wetlands in the global carbon cycle, particularly under a climate change scenario.

  13. Tunguska, 1908: the gas pouch and soil fluidization hypothesis

    NASA Astrophysics Data System (ADS)

    Nistor, I.

    2012-01-01

    The Siberian taiga explosion of 30 June 1908 remains one of the great mysteries of the 20th century: millions of trees put down over an area of 2200 km2 without trace of a crater or meteorite fragments. Hundred years of failed searches have followed, resulting in as many flawed hypothesis which could not offer satisfactory explanations: meteorite, comet, UFO, etc. In the author's opinion, the cause is that the energy the explorers looked for was simply not there! The author's hypothesis is that a meteoroid encountered a gas pouch in the atmosphere, producing a devastating explosion, its effects being amplified by soil fluidization.

  14. Soil pH management without lime, a strategy to reduce greenhouse gas emissions from cultivated soils

    NASA Astrophysics Data System (ADS)

    Nadeem, Shahid; Bakken, Lars; Reent Köster, Jan; Tore Mørkved, Pål; Simon, Nina; Dörsch, Peter

    2015-04-01

    For decades, agricultural scientists have searched for methods to reduce the climate forcing of food production by increasing carbon sequestration in the soil and reducing the emissions of nitrous oxide (N2O). The outcome of this research is depressingly meagre and the two targets appear incompatible: efforts to increase carbon sequestration appear to enhance the emissions of N2O. Currently there is a need to find alternative management strategies which may effectively reduce both the CO2 and N2O footprints of food production. Soil pH is a master variable in soil productivity and plays an important role in controlling the chemical and biological activity in soil. Recent investigations of the physiology of denitrification have provided compelling evidence that the emission of N2O declines with increasing pH within the range 5-7. Thus, by managing the soil pH at a near neutral level appears to be a feasible way to reduce N2O emissions. Such pH management has been a target in conventional agriculture for a long time, since a near-neutral pH is optimal for a majority of cultivated plants. The traditional way to counteract acidification of agricultural soils is to apply lime, which inevitably leads to emission of CO2. An alternative way to increase the soil pH is the use of mafic rock powders, which have been shown to counteract soil acidification, albeit with a slower reaction than lime. Here we report a newly established field trail in Norway, in which we compare the effects of lime and different mafic mineral and rock powders (olivine, different types of plagioclase) on CO2 and N2O emissions under natural agricultural conditions. Soil pH is measured on a monthly basis from all treatment plots. Greenhouse gas (GHG) emission measurements are carried out on a weekly basis using static chambers and an autonomous robot using fast box technique. Field results from the first winter (fallow) show immediate effect of lime on soil pH, and slower effects of the mafic rocks. The

  15. Soil gas carbon dioxide probe: laboratory testing and field evaluation.

    PubMed

    Patterson, B M; Furness, A J; Bastow, T P

    2013-05-01

    An automated semi-continuous on-line instrument has been developed to measure CO2 gas concentrations in the vadose zone. The instrument uses semi-permeable polymer tubing (CO2 probe) for diffusion based sampling, coupled to an infra red sensor. The system operated automatically by intermittently purging the CO2 probe, which was installed in the vadose zone, with a non-CO2 gas at a low flow rate. The gas exiting the CO2 probe was monitored at the ground surface using a miniature infra red sensor and the response related to the vadose zone soil gas CO2 concentration. The in situ CO2 probes provided a reliable monitoring technique under long-term (18 months) aggressive and dynamic field conditions, with no interference observed from non-CO2 gases and volatile organic compounds. The probes provided data that were comparable to conventional grab sampling techniques without the labour-intensive sample collection and processing associated with these conventional techniques. Also, disturbance to vadose zone CO2 profiles from repeated grab samples during long-term semi-continuous monitoring could potential be reduced by using the diffusion based sampling technique.

  16. Soil gas Rn monitoring at Chã das Caldeiras prior the 2014-15 Fogo eruption, Cape Verde

    NASA Astrophysics Data System (ADS)

    Padilla, Germán; Barrancos, José; Dionis, Samara; Fernandes, Paulo; Pérez, Nemesio M.; Sagiya, Takeshi; Padrón, Eleazar; Melián, Gladys V.; Hernández, Pedro A.; Silva, Sónia; Pereira, José Manuel; Rodríguez, Fátima; Asensio-Ramos, María; Calvo, David; Semedo, Helio

    2015-04-01

    Since 2007 the ITER-INVOLCAN/UNICV-OVCV/SNPC research team has implemented a geochemical program for the volcanic surveillance of Fogo volcano by means of applying different geochemical methods in a regularly basis (diffuse degassing surveys, fumarole gas sampling, etc.). This program was improved by setting up a geochemical permanent station (CHA01) to perform continuous measurements of soil gas radon (222Rn) and thoron (220Rn) activities at Chã das Caldeiras, more specific in Portela village, since April 20, 2013. Both gases are characterized to ascend towards the surface mainly through cracks or faults via diffusion and/or advection mechanisms dependent of both soil porosity and permeability, which in turn vary as a function of the stress/strain changes at depth. Measurements of 222Rn and 220Rn activities were performed by an alpha-spectrometer after pumping the soil gas from a thermally isolated PVC pipe inserted 1m in the ground. Even though during the study period the recorded data did not show high 222Rn activity values, a change in the temporal evolution of soil gas 222Rn activity was observed. During the first six months, from April to October, 2013, recorded time series of 222Rn and 220Rn activities showed normal background levels with values of 80.5 and 55.2 Bqm-3, respectively. However, from October, 2013, to February, 2014, 222Rn time series showed an increase trend reaching peak values of 396 Bqm-3 and having an average activity of 134 Bqm-3 until the removal of the station on November 25, 2014 due to the potential danger of being destroyed by the lava flows. The observed increase in the soil gas 222Rn activity from October 2013 to February 2014 occurs almost at the same time of slight observed changes in the vertical displacements detected by the geodetic network installed at the Fogo Island by the ITER-INVOLCAN/UNICV-OVCV/SNPC/Nagoya University research team. Since seismic data are not available, we cannot conclude if the observed changes in soil

  17. Assessment of Soil-Gas and Soil Contamination at the Former Military Police Range, Fort Gordon, Georgia, 2009-2010

    USGS Publications Warehouse

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

    2011-01-01

    Soil gas and soil were assessed for organic and inorganic contaminants at the former military police range at Fort Gordon, Georgia, from May to September 2010. The assessment evaluated organic contaminants in soil-gas samplers and inorganic contaminants in soil samples. This assessment was conducted to provide environmental contamination data to Fort Gordon pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Soil-gas samplers deployed and collected from May 20 to 24, 2010, identified masses above method detection level for total petroleum hydrocarbons, gasoline-related and diesel-related compounds, and chloroform. Most of these detections were in the southwestern quarter of the study area and adjacent to the road on the eastern boundary of the site. Nine of the 11 chloroform detections were in the southern half of the study area. One soil-gas sampler deployed adjacent to the road on the southern boundary of the site detected a mass of tetrachloroethene greater than, but close to, the method detection level of 0.02 microgram. For soil-gas samplers deployed and collected from September 15 to 22, 2010, none of the selected organic compounds classified as chemical agents and explosives were detected above method detection levels. Inorganic concentrations in the five soil samples collected at the site did not exceed the U.S. Environmental Protection Agency regional screening levels for industrial soil and were at or below background levels for similar rocks and strata in South Carolina.

  18. Radon anomaly in soil gas as an earthquake precursor.

    PubMed

    Miklavcić, I; Radolić, V; Vuković, B; Poje, M; Varga, M; Stanić, D; Planinić, J

    2008-10-01

    The mechanical processes of earthquake preparation are always accompanied by deformations; afterwards, the complex short- or long-term precursory phenomena can appear. Anomalies of radon concentrations in soil gas are registered a few weeks or months before many earthquakes. Radon concentrations in soil gas were continuously measured by the LR-115 nuclear track detectors at site A (Osijek) during a 4-year period, as well as by the Barasol semiconductor detector at site B (Kasina) during 2 years. We investigated the influence of the meteorological parameters on the temporal radon variations, and we determined the equation of the multiple regression that enabled the reduction (deconvolution) of the radon variation caused by the barometric pressure, rainfall and temperature. The pre-earthquake radon anomalies at site A indicated 46% of the seismic events, on criterion M>or=3, R<200 km, and 21% at site B. Empirical equations between earthquake magnitude, epicenter distance and precursor time enabled estimation or prediction of an earthquake that will rise at the epicenter distance R from the monitoring site in expecting precursor time T.

  19. Evaluation of soil-gas transport of organic chemicals into residential buildings: Final report

    SciTech Connect

    Hodgson, A.T.; Garbesi, K.; Sextro, R.G.; Daisey, J.M.

    1988-06-01

    This investigation consisted of theoretical, laboratory, and field study phases with the overall objective of determining the importance of pressure-driven flow of soil gas in the transport of volatile organic compounds (VOC) from soil into a house. In the first phase, the mechanisms of advection, diffusion, and retardation of VOC in soil were evaluated. Using the theory of fluid mechanics and empirical for equilibrium partitioning of VOC among gas, aqueous, and solid phase of soil, a one-dimensional advection-diffusion equation or the transport of gas-phase VOC through soil was developed. An experimental apparatus and method were developed for the direct observation of pressure-driven transport of VOC through soil under controlled laboratory conditions. The retardation of sulfur hexafluoride (SF/sub 6/) and hexafluorobenzene with respect to the flow of the bulk gas was measured in soil-column experiments using different soils and soil-moisture conditions. The results were in good agreement with theoretical predictions. Since SF/sub 6/ was not lost by sorption to soil, it was selected for use as a tracer gas in the field study to study the advective flow of soil gas. The overall objective of the investigation was directly addressed by the field study. This study was conducted at a house which has a basement and which was located adjacent to a covered municipal landfill. The soil at the site was characterized, pressure coupling between the basement and surrounding soil was measured, the entry rate of soil gas as a function of basement depressurization was measured, and VOC in soil gas, indoor air and outdoor air were quantified. 46 refs., 18 figs., 11 tabs.

  20. Pedologic and climatic controls on Rn-222 concentrations in soil gas, Denver, Colorado

    SciTech Connect

    Asher-Bolinder, S.; Owen, D.E.; Schumann, R.R. )

    1990-05-01

    Soil-gas radon concentrations are controlled seasonally by factors of climate and pedology. In a swelling soil of the semiarid Western United States, soil-gas radon concentrations at 100 cm depth increase in winter and spring due to increased emanation with higher soil moisture and the capping effect of surface water or ice. Increased soil moisture results from a combination of higher winter and spring precipitation and decreased insolation in fall and winter, lowering soil temperatures so that water infiltrates deeper and evaporates more slowly. Radon concentrations in soil drop markedly through the summer and fall. The increased insolation of spring and summer warms and dries the soil, limiting the amount of water that reaches 100 cm. As the soil dries, radon emanation decreases, and deep soil cracks develop. These cracks aid convective transport of soil gas, increase radon's flux into the atmosphere, and lower its concentration in soil gas. Probable controls on the distribution of uranium within the soil column include its downward leaching, its precipitation or adsorption onto B-horizon clays, concretions, or cement, and the uranium content and mineralogy of the soil's granitic and gneissic precursors.

  1. Interacting biochemical and diffusive controls on trace gas sources in unsaturated soils

    NASA Astrophysics Data System (ADS)

    Rubol, S.; Manzoni, S.; Bellin, A.; Porporato, A. M.

    2011-12-01

    Microbes react to environmental conditions on different timescales. When conditions improve (e.g., rewetting, substrate amendment), the residing population exits the dormant state, becomes active and starts synthesizing extra-cellular enzymes. If substrate availability, and hence energy, is sufficient, microbes may start to reproduce and increase the size of their population. These dynamics make it complicated to interpret measured relationships between microbial activity (e.g., respiration, denitrification, N mineralization) and environmental conditions. In particular, the relationship between bacterial activity and soil moisture, which is derived by incubating soil samples at constant soil moisture levels, seems to vary under dynamic hydrological conditions. This may be related to both soil physical properties and the resilience of bacteria to adapt to rapid changes in soil moisture. We present a process-based model that includes both the above effects and test the hypothesis that the ratio of the time scale of biological versus physical factors determines the shape describing the relationship between microbial activity and soil moisture. In particular, we focus on the role of oxygen dynamics, which regulate the prevalence of aerobic versus anaerobic conditions and thus the prevalence of nitrification versus denitrification. We identify and compare the time scale of the biological oxygen consumption with the time scale of physical diffusion. Starting from well-aerated conditions, as bacteria consume O2 in solution, more oxygen dissolves from the atmosphere - depending on gas-filled porosity. If water dynamics or tillage limits re-aeration, this can affect the equilibrium between the aqueous and the gaseous phase and thus alter the time scale of the reactions. This balance between consumption and re-aeration by diffusion ultimately controls the water quality as well the production of trace gases.

  2. Alteration of natural (37)Ar activity concentration in the subsurface by gas transport and water infiltration.

    PubMed

    Guillon, Sophie; Sun, Yunwei; Purtschert, Roland; Raghoo, Lauren; Pili, Eric; Carrigan, Charles R

    2016-05-01

    High (37)Ar activity concentration in soil gas is proposed as a key evidence for the detection of underground nuclear explosion by the Comprehensive Nuclear Test-Ban Treaty. However, such a detection is challenged by the natural background of (37)Ar in the subsurface, mainly due to Ca activation by cosmic rays. A better understanding and improved capability to predict (37)Ar activity concentration in the subsurface and its spatial and temporal variability is thus required. A numerical model integrating (37)Ar production and transport in the subsurface is developed, including variable soil water content and water infiltration at the surface. A parameterized equation for (37)Ar production in the first 15 m below the surface is studied, taking into account the major production reactions and the moderation effect of soil water content. Using sensitivity analysis and uncertainty quantification, a realistic and comprehensive probability distribution of natural (37)Ar activity concentrations in soil gas is proposed, including the effects of water infiltration. Site location and soil composition are identified as the parameters allowing for a most effective reduction of the possible range of (37)Ar activity concentrations. The influence of soil water content on (37)Ar production is shown to be negligible to first order, while (37)Ar activity concentration in soil gas and its temporal variability appear to be strongly influenced by transient water infiltration events. These results will be used as a basis for practical CTBTO concepts of operation during an OSI.

  3. Effects of biochar and other amendments on the physical properties and greenhouse gas emissions of an artificially degraded soil.

    PubMed

    Mukherjee, A; Lal, R; Zimmerman, A R

    2014-07-15

    Short and long-term impacts of biochar on soil properties under field conditions are poorly understood. In addition, there is a lack of field reports of the impacts of biochar on soil physical properties, gaseous emissions and C stability, particularly in comparison with other amendments. Thus, three amendments - biochar produced from oak at 650°C, humic acid (HA) and water treatment residual - (WTR) were added to a scalped silty-loam soil @ 0.5% (w/w) in triplicated plots under soybean. Over the 4-month active growing season, all amendments significantly increased soil pH, but the effect of biochar was the greatest. Biochar significantly increased soil-C by 7%, increased sub-nanopore surface area by 15% and reduced soil bulk density by 13% compared to control. However, only WTR amendment significantly increased soil nanopore surface area by 23% relative to the control. While total cumulative CH4 and CO2 emissions were not significantly affected by any amendment, cumulative N2O emission was significantly decreased in the biochar-amended soil (by 92%) compared to control over the growing period. Considering both the total gas emissions and the C removed from the atmosphere as crop growth and C added to the soil, WTR and HA resulted in net soil C losses and biochar as a soil C gain. However, all amendments reduced the global warming potential (GWP) of the soil and biochar addition even produced a net negative GWP effect. The short observation period, low application rate and high intra-treatment variation resulted in fewer significant effects of the amendments on the physicochemical properties of the soils than one might expect indicating further possible experimentation altering these variables. However, there was clear evidence of amendment-soil interaction processes affecting both soil properties and gaseous emissions, particularly for biochar, that might lead to greater changes with additional field emplacement time.

  4. Soil and Water Conservation Activities for Scouts.

    ERIC Educational Resources Information Center

    Soil Conservation Service (USDA), Washington, DC.

    The purpose of the learning activities outlined in this booklet is to help Scouts understand some conservation principles which hopefully will lead to the development of an attitude of concern for the environment and a commitment to help with the task of using and managing soil, water, and other natural resources for long range needs as well as…

  5. Effects of electrolytes, soil and soil minerals on CH4 recovery from gas hydrates with CO2

    NASA Astrophysics Data System (ADS)

    Lee, N.; Lee, W.

    2012-12-01

    Large amount of natural gas hydrates, which are known as future energy source, are stored in permafrost regions and under subsea sediments. One of innovative CH4 recovery mechanism from clathrate hydrates is swapping CH4 molecules by CO2 in cage structure. It can provide not only a promising solution for scarcity of energy, also a carbon reduction method for global warming. Previous studies on swapping have been conducted majorly with pure gas hydrates and a little consideration of geochemical factors recently begins. For future application in real environment of CH4 and CO2 replacement process, thorough investigation on the effect of electrolytes, soil and soil minerals, which are coexisted with gas hydrates under deep-sea sediment, is required. In this study, for understanding the impact of changes of surrounding matters, recovery ratio of CH4 during swapping process is measured as time passed with electrolytes (NaCl, MgCl2, CaCl2, KCl), soil (soil, marine sediment) and soil minerals (montmorillonite, kaolinite, nontronite, pyrite) by gas chromatography (GC). Replacement rates between CH4 and CO2 of samples reach the maximum replacement rate which can occur with pure hydrates sample in the last, however the required time is varied according to samples. There is the tendency that takes more time with soil and soil minerals than others due to the hydrates which are placed in the structure of soil and soil minerals. The experimental results imply that electrolytes, soil and soil minerals have significant effects on CH4 recovery by CO2 in gas hydrates. It could be applicable to excavate CH4 from hydrate deposits and also store the CO2 in existed hydrates structures in the future.

  6. Agricultural soil greenhouse gas emissions: a review of national inventory methods.

    PubMed

    Lokupitiya, Erandathie; Paustian, Keith

    2006-01-01

    Parties to the United Nations Framework Convention on Climate Change (UNFCCC) are required to submit national greenhouse gas (GHG) inventories, together with information on methods used in estimating their emissions. Currently agricultural activities contribute a significant portion (approximately 20%) of global anthropogenic GHG emissions, and agricultural soils have been identified as one of the main GHG source categories within the agricultural sector. However, compared to many other GHG sources, inventory methods for soils are relatively more complex and have been implemented only to varying degrees among member countries. This review summarizes and evaluates the methods used by Annex 1 countries in estimating CO2 and N2O emissions in agricultural soils. While most countries utilize the Intergovernmental Panel on Climate Change (IPCC) default methodology, several Annex 1 countries are developing more advanced methods that are tailored for specific country circumstances. Based on the latest national inventory reporting, about 56% of the Annex 1 countries use IPCC Tier 1 methods, about 26% use Tier 2 methods, and about 18% do not estimate or report N2O emissions from agricultural soils. More than 65% of the countries do not report CO2 emissions from the cultivation of mineral soils, organic soils, or liming, and only a handful of countries have used country-specific, Tier 3 methods. Tier 3 methods usually involve process-based models and detailed, geographically specific activity data. Such methods can provide more robust, accurate estimates of emissions and removals but require greater diligence in documentation, transparency, and uncertainty assessment to ensure comparability between countries. Availability of detailed, spatially explicit activity data is a major constraint to implementing higher tiered methods in many countries.

  7. Enzyme activities by indicator of quality in organic soil

    NASA Astrophysics Data System (ADS)

    Raigon Jiménez, Mo; Fita, Ana Delores; Rodriguez Burruezo, Adrián

    2016-04-01

    The analytical determination of biochemical parameters, as soil enzyme activities and those related to the microbial biomass is growing importance by biological indicator in soil science studies. The metabolic activity in soil is responsible of important processes such as mineralization and humification of organic matter. These biological reactions will affect other key processes involved with elements like carbon, nitrogen and phosphorus , and all transformations related in soil microbial biomass. The determination of biochemical parameters is useful in studies carried out on organic soil where microbial processes that are key to their conservation can be analyzed through parameters of the metabolic activity of these soils. The main objective of this work is to apply analytical methodologies of enzyme activities in soil collections of different physicochemical characteristics. There have been selective sampling of natural soils, organic farming soils, conventional farming soils and urban soils. The soils have been properly identified conserved at 4 ° C until analysis. The enzyme activities determinations have been: catalase, urease, cellulase, dehydrogenase and alkaline phosphatase, which bring together a representative group of biological transformations that occur in the soil environment. The results indicate that for natural and agronomic soil collections, the values of the enzymatic activities are within the ranges established for forestry and agricultural soils. Organic soils are generally higher level of enzymatic, regardless activity of the enzyme involved. Soil near an urban area, levels of activities have been significantly reduced. The vegetation cover applied to organic soils, results in greater enzymatic activity. So the quality of these soils, defined as the ability to maintain their biological productivity is increased with the use of cover crops, whether or spontaneous species. The practice of cover based on legumes could be used as an ideal choice

  8. Soil greenhouse gas emissions affected by sheep grazing under dryland cropping systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sheep grazing to control weeds during fallow may influence soil greenhouse gas (CO2, N2O, and CH4) emissions by consuming crop residue and returning feces and urine to the soil. An experiment was conducted to evaluate the effect of sheep grazing compared to herbicide application on soil temperature ...

  9. Dissolved gas dynamics in wetland soils: Root-mediated gas transfer kinetics determined via push-pull tracer tests

    NASA Astrophysics Data System (ADS)

    Reid, Matthew C.; Pal, David S.; Jaffé, Peter R.

    2015-09-01

    Gas transfer processes are fundamental to the biogeochemical and water quality functions of wetlands, yet there is limited knowledge of the rates and pathways of soil-atmosphere exchange for gases other than oxygen and methane (CH4). In this study, we use a novel push-pull technique with sulfur hexafluoride (SF6) and helium (He) as dissolved gas tracers to quantify the kinetics of root-mediated gas transfer, which is a critical efflux pathway for gases from wetland soils. This tracer approach disentangles the effects of physical transport from simultaneous reaction in saturated, vegetated wetland soils. We measured significant seasonal variation in first-order gas exchange rate constants, with smaller spatial variations between different soil depths and vegetation zones in a New Jersey tidal marsh. Gas transfer rates for most biogeochemical trace gases are expected to be bracketed by the rate constants for SF6 and He, which ranged from ˜10-2 to 2 × 10-1 h-1 at our site. A modified Damköhler number analysis is used to evaluate the balance between biochemical reaction and root-driven gas exchange in governing the fate of environmental trace gases in rooted, anaerobic soils. This approach confirmed the importance of plant gas transport for CH4, and showed that root-driven transport may affect nitrous oxide (N2O) balances in settings where N2O reduction rates are slow.

  10. Role of organic amendment application on greenhouse gas emission from soil.

    PubMed

    Thangarajan, Ramya; Bolan, Nanthi S; Tian, Guanglong; Naidu, Ravi; Kunhikrishnan, Anitha

    2013-11-01

    Globally, substantial quantities of organic amendments (OAs) such as plant residues (3.8×10(9) Mg/yr), biosolids (10×10(7) Mg/yr), and animal manures (7×10(9) Mg/yr) are produced. Recycling these OAs in agriculture possesses several advantages such as improving plant growth, yield, soil carbon content, and microbial biomass and activity. Nevertheless, OA applications hold some disadvantages such as nutrient eutrophication and greenhouse gas (GHG) emission. Agriculture sector plays a vital role in GHG emission (carbon dioxide- CO2, methane- CH4, and nitrous oxide- N2O). Though CH4 and N2O are emitted in less quantity than CO2, they are 21 and 310 times more powerful in global warming potential, respectively. Although there have been reviews on the role of mineral fertilizer application on GHG emission, there has been no comprehensive review on the effect of OA application on GHG emission in agricultural soils. The review starts with the quantification of various OAs used in agriculture that include manures, biosolids, and crop residues along with their role in improving soil health. Then, it discusses four major OA induced-GHG emission processes (i.e., priming effect, methanogenesis, nitrification, and denitrification) by highlighting the impact of OA application on GHG emission from soil. For example, globally 10×10(7) Mg biosolids are produced annually which can result in the potential emission of 530 Gg of CH4 and 60 Gg of N2O. The article then aims to highlight the soil, climatic, and OA factors affecting OA induced-GHG emission and the management practices to mitigate the emission. This review emphasizes the future research needs in relation to nitrogen and carbon dynamics in soil to broaden the use of OAs in agriculture to maintain soil health with minimum impact on GHG emission from agriculture.

  11. Pedologic and climatic controls on Rn-222 concentrations in soil gas, Denver, Colorado

    USGS Publications Warehouse

    Asher-Bolinder, S.; Owen, D.E.; Schumann, R.R.

    1990-01-01

    Soil-gas radon concentrations are controlled seasonally by factors of climate and pedology. In a swelling soil of the semiarid Western United States, soil-gas radon concentrations at 100 cm depth increase in winter and spring due to increased emanation with higher soil moisture and the capping effect of surface water or ice. Radon concentrations in soil drop markedly through the summer and fall. The increased insolation of spring and summer warms and dries the soil, limiting the amount of water that reaches 100 cm. Probable controls on the distribution of uranium within the soil column include its downward leaching, its precipitation or adsorption onto B-horizon clays, concretions, or cement, and the uranium content and mineralogy of the soil's granitic and gneissic precursors. -from Authors

  12. (220)Rn/(222)Rn isotope pair as a natural proxy for soil gas transport.

    PubMed

    Huxol, Stephan; Brennwald, Matthias S; Henneberger, Ruth; Kipfer, Rolf

    2013-12-17

    Radon (Rn) is a naturally occurring radioactive noble gas, which is ubiquitous in soil gas. Especially, its long-lived isotope (222)Rn (half-life: 3.82 d) gained widespread acceptance as a tracer for gas transport in soils, while the short-lived (220)Rn (half-life: 55.6 s) found less interest in environmental studies. However, in some cases, the application of (222)Rn as a tracer in soil gas is complex as its concentrations can be influenced by changes of the transport conditions or of the (222)Rn production of the soil material. Due to the different half-lives of (220)Rn and (222)Rn, the distances that can be traveled by the respective isotopes before decay differ significantly, with (220)Rn migrating over much shorter distances than (222)Rn. Therefore, the soil gas concentrations of (220)Rn and (222)Rn are influenced by processes on different length scales. In laboratory experiments in a sandbox, we studied the different transport behaviors of (220)Rn and (222)Rn resulting from changing the boundary conditions for diffusive transport and from inducing advective gas movements. From the results gained in the laboratory experiments, we propose the combined analysis of (220)Rn and (222)Rn to determine gas transport processes in soils. In a field study on soil gases in the cover soil of a capped landfill we applied the combined analysis of (220)Rn and (222)Rn in soil gas for the first time and showed the feasibility of this approach to characterize soil gas transport processes.

  13. Effects of biochar and elevated soil temperature on soil microbial activity and abundance in an agricultural system

    NASA Astrophysics Data System (ADS)

    Bamminger, Chris; Poll, Christian; Marhan, Sven

    2014-05-01

    As a consequence of Global Warming, rising surface temperatures will likely cause increased soil temperatures. Soil warming has already been shown to, at least temporarily, increase microbial activity and, therefore, the emissions of greenhouse gases like CO2 and N2O. This underlines the need for methods to stabilize soil organic matter and to prevent further boost of the greenhouse gas effect. Plant-derived biochar as a soil amendment could be a valuable tool to capture CO2 from the atmosphere and sequestrate it in soil on the long-term. During the process of pyrolysis, plant biomass is heated in an oxygen-low atmosphere producing the highly stable solid matter biochar. Biochar is generally stable against microbial degradation due to its chemical structure and it, therefore, persists in soil for long periods. Previous experiments indicated that biochar improves or changes several physical or chemical soil traits such as water holding capacity, cation exchange capacity or soil structure, but also biotic properties like microbial activity/abundance, greenhouse gas emissions and plant growth. Changes in the soil microbial abundance and community composition alter their metabolism, but likely also affect plant productivity. The interaction of biochar addition and soil temperature increase on soil microbial properties and plant growth was yet not investigated on the field scale. To investigate whether warming could change biochar effects in soil, we conducted a field experiment attached to a soil warming experiment on an agricultural experimental site near the University of Hohenheim, already running since July 2008. The biochar field experiment was set up as two-factorial randomized block design (n=4) with the factors biochar amendment (0, 30 t ha-1) and soil temperature (ambient, elevated=ambient +2.5° C) starting from August 2013. Each plot has a dimension of 1x1m and is equipped with combined soil temperature and moisture sensors. Slow pyrolysis biochar from the C

  14. Measurements of soil permeability and pressure fields in EPA's soil-gas chamber. Report for May-August 1993

    SciTech Connect

    Mosley, R.B.; Snoddy, R.; Brubaker, S.A.

    1993-01-01

    The paper discusses the measurement of soil permeability and pressure fields using EPA's soil-gas chamber, designed to study the production and transport of radon and other potential indoor air pollutants originating in soils. The chamber is instrumented to measure distributions of radon and pressure fields and also moisture distributions and their resulting influence on soil permeability. An analytic solution for advective flow in the soil-gas chamber is presented which includes the effects of moisture-dependent spatial variations of the permeability. Measurements of the pressure field are compared with model calculations. Relatively good agreement between the measurements and calculations is obtained, except near the water level where boundary conditions are not rigorously satisfied.

  15. Soil CO2 constrain and distinction of root respiration and microbial activity by soil CO2 and CH4 profile

    NASA Astrophysics Data System (ADS)

    Ji, S.; Breecker, D.; Nie, J.

    2015-12-01

    Profiles of soil pore space CO2 and CH4 concentrations are rarely reported, especially from the same soils, yet are important for a number of applications. First, quantifying the component of respired CO2 in the soil pore spaces improves paleosol-based paleo-atmospheric CO2 estimates. Second, profiles can be used to estimate the average depth of biological activity (e.g. respiration and CH4 oxidation). Third, CH4 profiles, by identifying microbial activity, may help distinguish root/rhizosphere respiration from microbial decomposition. Here, we report soil CO2 and CH4 profiles measured at the Semi-Arid Climate Observatory and Laboratory (SACOL) on the Chinese Loess Plateau (CLP) at Lanzhou University, Gansu, China. Soil parent material on the site is mainly Quaternary aeolian loess and classifies as an Entisol. Soil respired CO2 (S(z) = soil CO2 - atmospheric CO2) is the most uncertain variable required to reconstruct ancient atmospheric CO2 concentrations from paleosol carbonates. Our direct soil pore space CO2 measurements show that S(z) values varied from ~100ppmV during the spring to ~2200ppmV during the summer. S(z) average 390 ± 30ppmV during May before the summer monsoon begins when soil temperature is increasing, soil water content is at a minimum and pedogenic carbonate may be forming. This value lies in the range of S(z) values previously estimated for surface Inceptisols (300 ± 100ppmV, Breecker 2013) and is lower than Pleistocene CLP paleosols (Da et al.,2015) in similar parent material. Our direct measurements of soil pore space CO2 thus support these previous independent S(z) estimates. We also investigate the average depth of CH4 oxidation and soil respiration, which range from 3-10cm and at least 20cm, respectively, using the shapes of soil gas profiles. Fitting observed soil CO2 and CH4 profiles with a production-diffusion model show that the average depth of CH4 oxidation was always at least 10 cm shallower than the average depth of respiration

  16. Effects of electrokinetic treatment of a heavy metal contaminated soil on soil enzyme activities.

    PubMed

    Cang, Long; Zhou, Dong-Mei; Wang, Quan-Ying; Wu, Dan-Ya

    2009-12-30

    There is a growing concern on the potential application of a direct current (DC) electric field to soil for removing contaminants, but little is known about its impact on soil enzyme activities. This study investigated the change of enzyme activities of a heavy metal contaminated soil before and after electrokinetic (EK) treatments at lab-scale and the mechanisms of EK treatment to affect soil enzyme activities were explored. After treatments with 1-3 V cm(-1) of voltage gradient for 420 h, soil pH, electrical conductivity (EC), soil organic carbon, dissolved organic carbon (DOC), soil heavy metal concentration and enzyme activities were analyzed. The results showed that the average removal efficiencies of soil copper were about 65% and 83% without and with pH control of catholyte, respectively, and all the removal efficiencies of cadmium were above 90%. The soil invertase and catalase activities increased and the highest invertase activity was as 170 times as the initial one. The activities of soil urease and acidic phosphatase were lower than the initial ones. Bivariate correlation analyses indicated that the soil invertase and acidic phosphatase activities were significantly correlated with soil pH, EC, and DOC at P<0.05, but the soil urease activities had no correlation with the soil properties. On the other hand, the effects of DC electric current on solution invertase and catalase enzyme protein activities indicated that it had negative effect on solution catalase activity and little effect on solution invertase activity. From the change of invertase and catalase activities in soil and solution, the conclusion can be drawn that the dominant effect mechanism is the change of soil properties by EK treatments.

  17. The mechanisms governing low denitrification capacity and high nitrogen oxide gas emissions in subtropical forest soils in China

    NASA Astrophysics Data System (ADS)

    Zhang, Jinbo; Yu, Yongjie; Zhu, Tongbin; Cai, Zucong

    2014-08-01

    Previous studies have demonstrated that denitrification rates are low in subtropical forest soils. However, the mechanisms governing this process are not well known. This study seeks to identify the mechanisms responsible for the low denitrification capacity and high nitrogen oxide gas ratio in subtropical forest soils in China. The denitrification capacity and nitric oxide (NO), nitrous oxide (N2O), and dinitrogen (N2) emission rates were measured using the acetylene inhibition method under conditions of added nitrate and anoxia. The abundance of nitrate reductase (narG), nitrite reductase (nirK), nitric oxide reductase (cnorB), and nitrous oxide reductase (nosZ) was measured using real-time, quantitative polymerase chain reaction, and sequencing of the nirK and norB products was performed to analyze the population structure of denitrifying bacteria. These results showed that the denitrification capacity in subtropical forest soils was lower than in temperate forest soils (p < 0.05). Multiple regression analysis showed that redox potential at the start of incubation (Ehi), rather than soil pH or soil organic C, was the key soil variable influencing denitrification, and Ehi alone could explain 68% of the variations in denitrification capacity. The high Ehi in subtropical soils led to a low abundance of nirK and significant differences in the population structure of denitrifying bacteria between subtropical and temperate soils. Therefore, Ehi was responsible for the low denitrification capacity in subtropical forest soils. The ratio of NO to total denitrification gas products (p < 0.01) and the ratio of NO and N2O to total denitrification gas products (p < 0.05) were significantly higher in subtropical forest soils than in temperate forest soils, while the reverse trend was observed for the ratio of N2 to total denitrification gas products (p < 0.05). A high Ehi reduced the specific reduction activity of each nosZ copy and, in turn, resulted in a large ratio of NO

  18. Soil greenhouse gas fluxes from different tree species on Taihang Mountain, North China

    NASA Astrophysics Data System (ADS)

    Liu, X. P.; Zhang, W. J.; Hu, C. S.; Tang, X. G.

    2013-07-01

    The objectives of this study were to investigate seasonal variation of greenhouse gas fluxes from soils on sites dominated by plantation (Robinia pseudoacacia, Punica granatum, and Ziziphus jujube) and natural regenerated forests (Vitex negundo var. heterophylla, Leptodermis oblonga, and Bothriochloa ischcemum), and to identify how tree species, litter exclusion, and soil properties (soil temperature, soil moisture, soil organic carbon, total N, soil bulk density, and soil pH) explained the temporal and spatial variance in soil greenhouse gas fluxes. Fluxes of greenhouse gases were measured using static chamber and gas chromatography techniques. Six static chambers were randomly installed in each tree species. Three chambers were randomly designated to measure the impacts of surface litter exclusion, and the remaining three were used as a control. Field measurements were conducted biweekly from May 2010 through April 2012. Soil CO2 emissions from all tree species were significantly affected by soil temperature, soil moisture, and their interaction. Driven by the seasonality of temperature and precipitation, soil CO2 emissions demonstrated a clear seasonal pattern, with fluxes significantly higher during the rainy season than during the dry season. Soil CH4 and N2O fluxes were not significantly correlated with soil temperature, soil moisture, or their interaction, and no significant seasonal differences were detected. Soil CO2 and N2O fluxes were significantly correlated with soil organic carbon, total N, and soil bulk density, while soil pH was not correlated with CO2 and N2O emissions. Soil CH4 fluxes did not display pronounced dependency on soil organic carbon, total N, soil bulk density, and soil pH. Removal of surface litter resulted in significant decreases in CO2 emissions and CH4 uptakes, but had no significant influence on N2O fluxes. Soils in six tree species acted as sinks for atmospheric CH4. With the exception of Ziziphus jujube, Soils in all sites

  19. Activated Carbon Fibers For Gas Storage

    SciTech Connect

    Burchell, Timothy D; Contescu, Cristian I; Gallego, Nidia C

    2017-01-01

    The advantages of Activated Carbon Fibers (ACF) over Granular Activated Carbon (GAC) are reviewed and their relationship to ACF structure and texture are discussed. These advantages make ACF very attractive for gas storage applications. Both adsorbed natural gas (ANG) and hydrogen gas adsorption performance are discussed. The predicted and actual structure and performance of lignin-derived ACF is reviewed. The manufacture and performance of ACF derived monolith for potential automotive natural gas (NG) storage applications is reported Future trends for ACF for gas storage are considered to be positive. The recent improvements in NG extraction coupled with the widespread availability of NG wells means a relatively inexpensive and abundant NG supply in the foreseeable future. This has rekindled interest in NG powered vehicles. The advantages and benefit of ANG compared to compressed NG offer the promise of accelerated use of ANG as a commuter vehicle fuel. It is to be hoped the current cost hurdle of ACF can be overcome opening ANG applications that take advantage of the favorable properties of ACF versus GAC. Lastly, suggestions are made regarding the direction of future work.

  20. Adsorbed natural gas storage with activated carbon

    SciTech Connect

    Sun, Jian; Brady, T.A.; Rood, M.J.

    1996-12-31

    Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

  1. Exoenzyme activity in contaminated soils before and after soil washing: ß-glucosidase activity as a biological indicator of soil health.

    PubMed

    Chae, Yooeun; Cui, Rongxue; Woong Kim, Shin; An, Gyeonghyeon; Jeong, Seung-Woo; An, Youn-Joo

    2017-01-01

    It is essential to remediate or amend soils contaminated with various heavy metals or pollutants so that the soils may be used again safely. Verifying that the remediated or amended soils meet soil quality standards is an important part of the process. We estimated the activity levels of eight soil exoenzymes (acid phosphatase, arylsulfatase, catalase, dehydrogenase, fluorescein diacetate hydrolase, protease, urease, and ß-glucosidase) in contaminated and remediated soils from two sites near a non-ferrous metal smelter, using colorimetric and titrimetric determination methods. Our results provided the levels of activity of soil exoenzymes that indicate soil health. Most enzymes showed lower activity levels in remediated soils than in contaminated soils, with the exception of protease and urease, which showed higher activity after remediation in some soils, perhaps due to the limited nutrients available in remediated soils. Soil exoenzymes showed significantly higher activity in soils from one of the sites than from the other, due to improper conditions at the second site, including high pH, poor nutrient levels, and a high proportion of sand in the latter soil. Principal component analysis revealed that ß-glucosidase was the best indicator of soil ecosystem health, among the enzymes evaluated. We recommend using ß-glucosidase enzyme activity as a prior indicator in estimating soil ecosystem health.

  2. Soil greenhouse gas fluxes from different tree species on Taihang Mountain, North China

    NASA Astrophysics Data System (ADS)

    Liu, X. P.; Zhang, W. J.; Hu, C. S.; Tang, X. G.

    2014-03-01

    The objectives of this study were to investigate seasonal variation of greenhouse gas fluxes from soils on sites dominated by plantation (Robinia pseudoacacia, Punica granatum, and Ziziphus jujube) and natural regenerated forests (Vitex negundo var. heterophylla, Leptodermis oblonga, and Bothriochloa ischcemum), and to identify how tree species, litter exclusion, and soil properties (soil temperature, soil moisture, soil organic carbon, total N, soil bulk density, and soil pH) explained the temporal and spatial variation in soil greenhouse gas fluxes. Fluxes of greenhouse gases were measured using static chamber and gas chromatography techniques. Six static chambers were randomly installed in each tree species. Three chambers were randomly designated to measure the impacts of surface litter exclusion, and the remaining three were used as a control. Field measurements were conducted biweekly from May 2010 to April 2012. Soil CO2 emissions from all tree species were significantly affected by soil temperature, soil moisture, and their interaction. Driven by the seasonality of temperature and precipitation, soil CO2 emissions demonstrated a clear seasonal pattern, with fluxes significantly higher during the rainy season than during the dry season. Soil CH4 and N2O fluxes were not significantly correlated with soil temperature, soil moisture, or their interaction, and no significant seasonal differences were detected. Soil organic carbon and total N were significantly positively correlated with CO2 and N2O fluxes. Soil bulk density was significantly negatively correlated with CO2 and N2O fluxes. Soil pH was not correlated with CO2 and N2O emissions. Soil CH4 fluxes did not display pronounced dependency on soil organic carbon, total N, soil bulk density, and soil pH. Removal of surface litter significantly decreased in CO2 emissions and CH4 uptakes. Soils in six tree species acted as sinks for atmospheric CH4. With the exception of Ziziphus jujube, soils in all tree

  3. The Soil Moisture Active Passive (SMAP) applications activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Soil Moisture Active Passive (SMAP) mission is one of the first-tier satellite missions recommended by the U.S. National Research Council Committee on Earth Science and Applications from Space. The SMAP mission 1 is under development by NASA and is scheduled for launch late in 2014. The SMAP mea...

  4. Gas Transport Parameters for Landfill Final Cover Soil: Measurements and Model Modification by Dry Bulk Density

    NASA Astrophysics Data System (ADS)

    Wickramarachchi, P. N.; Kawamoto, K.; Hamamoto, S.; Nagamori, M.; Moldrup, P.; Komatsu, T.

    2011-12-01

    Landfill sites have been emerging in greenhouse warming scenarios as a significant source of atmospheric methane (CH4). Until recently, landfill management strategies have mainly addressed the problem of preventing groundwater contamination and reduction of leachate generation. Being one of the largest sources of anthropogenic CH4 emission, the final cover system should also be designed for minimizing the greenhouse gases migration into the atmosphere or the areas surrounding the landfill while securing the hydraulic performance. Compared to the intensive research efforts on hydraulic performances of landfill final cover soil, few studies about gas transport characteristics of landfill cover soils have been done. However, recent soil-gas studies implied that the effects of soil physical properties such as bulk density (i.e., compaction level), soil particle size are key parameters to understand landfill gaseous performance. The gas exchange through the final cover soils is controlled by advective and diffusive gas transport. Air permeability (ka) governs the advective gas transport while the soil-gas diffusion coefficient (Dp) governs diffusive gas transport. In this study, the effects of compaction level and particle size fraction effects on ka and Dp for landfill final cover soil was investigated. The disturbed soil samples were taken from landfill final cover in Japan. A compaction tests were performed for the soil samples with two different size fractions (< 35 mm and < 2.0 mm). In the compaction tests at field water content , the soil samples were repacked into soil cores (i.d. 15-cm, length 12-cm, 2120 cm3) at two different compaction levels [(MP):2700 kN/m2 and (SP):600 kN/m2]. After the compaction tests, ka and Dp were measured and then samples were saturated and subsequently drained at different soil-water matric potential of 0.98, 2.94, 9.81, 1235 kPa and with air-dried and oven-dried conditions. Results showed that measured Dp and ka values for the

  5. Making Activated Carbon for Storing Gas

    NASA Technical Reports Server (NTRS)

    Wojtowicz, Marek A.; Serio, Michael A.; Suuberg, Eric M.

    2005-01-01

    Solid disks of microporous activated carbon, produced by a method that enables optimization of pore structure, have been investigated as means of storing gas (especially hydrogen for use as a fuel) at relatively low pressure through adsorption on pore surfaces. For hydrogen and other gases of practical interest, a narrow distribution of pore sizes <2 nm is preferable. The present method is a variant of a previously patented method of cyclic chemisorption and desorption in which a piece of carbon is alternately (1) heated to the lower of two elevated temperatures in air or other oxidizing gas, causing the formation of stable carbon/oxygen surface complexes; then (2) heated to the higher of the two elevated temperatures in flowing helium or other inert gas, causing the desorption of the surface complexes in the form of carbon monoxide. In the present method, pore structure is optimized partly by heating to a temperature of 1,100 C during carbonization. Another aspect of the method exploits the finding that for each gas-storage pressure, gas-storage capacity can be maximized by burning off a specific proportion (typically between 10 and 20 weight percent) of the carbon during the cyclic chemisorption/desorption process.

  6. Calculating soil gas fluxes from gas concentration profiles: can we use standard DS models or should we use site-specific DS models?

    NASA Astrophysics Data System (ADS)

    Paulus, Sinikka; Jochheim, Hubert; Wirth, Stephan; Maier, Martin

    2015-04-01

    The apparent gas diffusion coefficient in soil (DS) is an important parameter describing soil aeration. It also links the profiles of soil gas concentration and soil gas flux using Fick's law. Soil gas diffusivity depends mainly on the structure of the pore system and the soil moisture status. There are several standard DS-models available that can easily be used for calculating DS. Another, more laborious option is to calibrate site specific DS models on soil core samples from the respective profile. We tested 4 standard DS models and a site-specific model and compared the resulting soil gas fluxes in two forest soils. Differences between the models were substantial. Another very important effect, however, is that standard DS models are usually derived from a single soil moisture measurement (device), that can result in an substantial offset in soil moisture estimation. The mean soil moisture content at a depth can be addressed more accurately by taking several soil cores. As a consequence, using standard DS models in combination with a single soil moisture measurement is less reliable than using site-specific models based on several soil samples.

  7. Intrinsic and induced isoproturon catabolic activity in dissimilar soils and soils under dissimilar land use.

    PubMed

    Reid, Brian J; Papanikolaou, Niki D; Wilcox, Ronah K

    2005-02-01

    The catabolic activity with respect to the systemic herbicide isoproturon was determined in soil samples by (14)C-radiorespirometry. The first experiment assessed levels of intrinsic catabolic activity in soil samples that represented three dissimilar soil series under arable cultivation. Results showed average extents of isoproturon mineralisation (after 240 h assay time) in the three soil series to be low. A second experiment assessed the impact of addition of isoproturon (0.05 microg kg(-1)) into these soils on the levels of catabolic activity following 28 days of incubation. Increased catabolic activity was observed in all three soils. A third experiment assessed levels of intrinsic catabolic activity in soil samples representing a single soil series managed under either conventional agricultural practice (including the use of isoproturon) or organic farming practice (with no use of isoproturon). Results showed higher (and more consistent) levels of isoproturon mineralisation in the soil samples collected from conventional land use. The final experiment assessed the impact of isoproturon addition on the levels of inducible catabolic activity in these soils. The results showed no significant difference in the case of the conventional farm soil samples while the induction of catabolic activity in the organic farm soil samples was significant.

  8. Geochemistry of soil gas in the seismic fault zone produced by the Wenchuan Ms 8.0 earthquake, southwestern China

    PubMed Central

    2010-01-01

    The spatio-temporal variations of soil gas in the seismic fault zone produced by the 12 May 2008 Wenchuan Ms 8.0 earthquake were investigated based on the field measurements of soil gas concentrations after the main shock. Concentrations of He, H2, CO2, CH4, O2, N2, Rn, and Hg in soil gas were measured in the field at eight short profiles across the seismic rupture zone in June and December 2008 and July 2009. Soil-gas concentrations of more than 800 sampling sites were obtained. The data showed that the magnitudes of the He and H2 anomalies of three surveys declined significantly with decreasing strength of the aftershocks with time. The maximum concentrations of He and H2 (40 and 279.4 ppm, respectively) were found in three replicates at the south part of the rupture zone close to the epicenter. The spatio-temporal variations of CO2, Rn, and Hg concentrations differed obviously between the north and south parts of the fault zone. The maximum He and H2 concentrations in Jun 2008 occurred near the parts of the rupture zone where vertical displacements were larger. The anomalies of He, H2, CO2, Rn, and Hg concentrations could be related to the variation in the regional stress field and the aftershock activity. PMID:21134257

  9. Impact of different tillage treatments on soil respiration and microbial activity for different agricultural used soils in Austria

    NASA Astrophysics Data System (ADS)

    Klik, Andreas; Scholl, Gerlinde; Baatar, Undrakh-Od

    2015-04-01

    Soils can act as a net sink for sequestering carbon and thus attenuating the increase in atmospheric carbon dioxide if appropriate soil and crop management is applied. Adapted soil management strategies like less intensive or even no tillage treatments may result in slower mineralization of soil organic carbon and enhanced carbon sequestration. In order to assess the impact of different soil tillage systems on carbon dioxide emissions due to soil respiration and on soil biological activity parameters, a field study of three years duration (2007-2010)has been performed at different sites in Austria. Following tillage treatments were compared: 1) conventional tillage (CT) with plough with and without cover crop during winter period, 2) reduced tillage (RT) with cultivator with cover crop, and 3) no-till (NT) with cover crop. Each treatment was replicated three times. At two sites with similar climatic conditions but different soil textures soil CO2 efflux was measured during the growing seasons in intervals of one to two weeks using a portable soil respiration system consisting of a soil respiration chamber attached to an infrared gas analyzer. Additionally, concurrent soil temperature and soil water contents of the top layer (0-5 cm)were measured. For these and additional three other sites with different soil and climatic conditions soil samples were taken to assess the impact of tillage treatment on soil biological activity parameters. In spring, summer and autumn samples were taken from each plot at the soil depth of 0-10, 10-20, and 20-30 cm to analyze soil microbial respiration (MR), substrate induced respiration (SIR), beta-glucasidase activity (GLU) and dehydrogenase (BHY). Samples were sieved (2 mm) and stored at 4 °C in a refrigerator. Analyses of were performed within one month after sampling. The measurements show a high spatial variability of soil respiration data even within one plot. Nevertheless, the level of soil carbon dioxide efflux was similar for

  10. Changes in liquid water alter nutrient bioavailability and gas diffusion in frozen antarctic soils contaminated with petroleum hydrocarbons.

    PubMed

    Harvey, Alexis Nadine; Snape, Ian; Siciliano, Steven Douglas

    2012-02-01

    Bioremediation has been used to remediate petroleum hydrocarbon (PHC)-contaminated sites in polar regions; however, limited knowledge exists in understanding how frozen conditions influence factors that regulate microbial activity. We hypothesized that increased liquid water (θ(liquid) ) would affect nutrient supply rates (NSR) and gas diffusion under frozen conditions. If true, management practices that increase θ(liquid) should also increase bioremediation in polar soils by reducing nutrient and oxygen limitations. Influence of θ(liquid) on NSR was determined using diesel-contaminated soil (0-8,000 mg kg(-1)) from Casey Station, Antarctica. The θ(liquid) was altered between 0.007 and 0.035 cm(3) cm(-3) by packing soil cores at different bulk densities. The nutrient supply rate of NH 4+ and NO 3-, as well as gas diffusion coefficient, D(s), were measured at two temperatures, 21°C and -5°C, to correct for bulk density effects. Freezing decreased NSR of both NH 4+ and NO 3-, with θ(liquid) linked to nitrate and ammonia NSR in frozen soil. Similarly for D(s), decreases due to freezing were much more pronounced in soils with low θ(liquid) compared to soils with higher θ(liquid) contents. Additional studies are needed to determine the relationship between degradation rates and θ(liquid) under frozen conditions.

  11. Reduced soil wettability can affect greenhouse gas fluxes

    NASA Astrophysics Data System (ADS)

    Urbanek, Emilia; Qassem, Khalid

    2015-04-01

    Soil moisture is known to be an important factor affecting the carbon (C) dynamics in soils including decomposition of organic matter and exchange of gases like CO2 and CH4 between the soil and the atmosphere. Most studies and process models looking at the soil C dynamics assume, however, that soils are easily wettable and water is relatively uniformly distributed within the soil pores. Most soils, however, do not wet spontaneously when dry or moderately moist, but instead exhibit some degree of soil water repellency (i.e. hydrophobicity), which can restrict infiltration and conductivity of water for weeks or months. This is world-wide occurring phenomenon which affects all soil textural types but is particularly common under permanent vegetation e.g. forest, grass and shrub vegetation. Soil water repellency is most profound during drier seasons, when the soil moisture content is relatively low. Although prolonged contact with water can gradually decrease water repellency, some soils do not recover to being completely wettable even after very wet winter months or substantial rainfall events. It has been recognized that with the predicted climatic changes the phenomenon of soil water repellency will become even more pronounced and severe, additionally it may occur in the areas and climatic zones where the effect have not been currently recognized. One of the main implications of soil water repellency is restricted water infiltration and reduced conductivity, which results in reduced soil water availability for plants and soil biota, even after prolonged periods of rainfall. As the process of C mineralization and consequently CO2 efflux from soil is driven by the accessibility of organic matter to decomposing organisms, which in turn is directly dependent on (i) soil moisture and (ii) soil temperature it is, therefore hypothesised that carbon decomposition and CO2 efflux in water repellent soils will also be affected when soil in the water repellent state. The CO2

  12. Nitrogen availability and indirect measurements of greenhouse gas emissions from aerobic and anaerobic biowaste digestates applied to agricultural soils.

    PubMed

    Rigby, H; Smith, S R

    2013-12-01

    turnover digestate N. In contrast to the sandy soil types, where nitrate (NO3-) concentrations increased during incubation, there was an absence of NO3- accumulation in the silty clay soil amended with LTAD and DMADMSW. This provided indirect evidence for denitrification activity and the gaseous loss of N, and the associated increased risk of greenhouse gas emissions under certain conditions of labile C supply and/or digestate physical structure in fine-textured soil types. The significance and influence of the interaction between soil type and digestate stability and physical properties on denitrification processes in digestate-amended soils require urgent investigation to ensure management practices are appropriate to minimise greenhouse gas emissions from land applied biowastes.

  13. Greenhouse gas emission and groundwater pollution potentials of soils amended with raw and carbonized swine solids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research is to study the greenhouse gas emission and groundwater pollution potentials of the soils amended with raw swine solids and swine biochars made from different thermochemical conditions. Triplicate sets of small pots were designed: 1) control soil with a 50/50 mixture o...

  14. Greenhouse gas emission and groundwater pollution potentials of soils amended with different swine biochars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to study the greenhouse gas emission and groundwater pollution potentials of the soils amended with various biochars using different biomass feedstocks and thermal processing conditions. Triplicate sets of small pots were designed; control soil consisting of Histi...

  15. Biochar alters manure's effect on nitrogen cycling and greenhouse gas emissions in a calcareous soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Few multiyear field studies have examined the impacts of a one-time biochar application on net N mineralization and greenhouse gas emissions in an irrigated, calcareous soil; yet such applications are hypothesized as a means of sequestering atmospheric CO2 and improving soil quality. We fall-applie...

  16. Sub-surface soil carbon changes affects biofuel greenhouse gas emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Changes in direct soil organic carbon (SOC) can have a major impact on overall greenhouse gas (GHG) emissions from biofuels when using life-cycle assessment (LCA). Estimated changes in SOC, when accounted for in an LCA, are typically derived from near-surface soil depths (<30 cm). Changes in subsurf...

  17. Soil physiochemical controls on trace gas emissions for a North Dakota mollisol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantification of trace gas emissions and an increased understanding of soil controls on emissions during freeze-thaw cycles are essential to refine climate change models. Six similar, intact soil cores were collected to a depth of 80 cm from an undisturbed prairie in central North Dakota. Trace g...

  18. Soil microbial activity as influenced by compaction and straw mulching

    NASA Astrophysics Data System (ADS)

    Siczek, A.; Frąc, M.

    2012-02-01

    Field study was performed on Haplic Luvisol soil to determine the effects of soil compaction and straw mulching on microbial parameters of soil under soybean. Treatments with different compaction were established on unmulched and mulched with straw soil. The effect of soil compaction and straw mulching on the total bacteria number and activities of dehydrogenases, protease, alkaline and acid phosphatases was studied. The results of study indicated the decrease of enzymes activities in strongly compacted soil and their increase in medium compacted soil as compared to no-compacted treatment. Mulch application caused stimulation of the bacteria total number and enzymatic activity in the soil under all compaction levels. Compaction and mulch effects were significant for all analyzed microbial parameters (P<0.001).

  19. Effect of liming on sulfate transformation and sulfur gas emissions in degraded vegetable soil treated by reductive soil disinfestation.

    PubMed

    Meng, Tianzhu; Zhu, Tongbin; Zhang, Jinbo; Cai, Zucong

    2015-10-01

    Reductive soil disinfestation (RSD), namely amending organic materials and mulching or flooding to create strong reductive status, has been widely applied to improve degraded soils. However, there is little information available about sulfate (SO4(2-)) transformation and sulfur (S) gas emissions during RSD treatment to degraded vegetable soils, in which S is generally accumulated. To investigate the effects of liming on SO4(2-) transformation and S gas emissions, two SO4(2-)-accumulated vegetable soils (denoted as S1 and S2) were treated by RSD, and RSD plus lime, denoted as RSD0 and RSD1, respectively. The results showed that RSD0 treatment reduced soil SO4(2-) by 51% and 61% in S1 and S2, respectively. The disappeared SO4(2-) was mainly transformed into the undissolved form. During RSD treatment, hydrogen sulfide (H2S), carbonyl sulfide (COS), and dimethyl sulfide (DMS) were detected, but the total S gas emission accounted for <0.006% of total S in both soils. Compared to RSD0, lime addition stimulated the conversion of SO4(2-) into undissolved form, reduced soil SO4(2-) by 81% in S1 and 84% in S2 and reduced total S gas emissions by 32% in S1 and 57% in S2, respectively. In addition to H2S, COS and DMS, the emissions of carbon disulfide, methyl mercaptan, and dimethyl disulfide were also detected in RSD1 treatment. The results indicated that RSD was an effective method to remove SO4(2-), liming stimulates the conversion of dissolved SO4(2-) into undissolved form, probably due to the precipitation with calcium.

  20. Effects of soil type and farm management on soil ecological functional genes and microbial activities

    SciTech Connect

    Reeve, Jennifer; Schadt, Christopher Warren; Carpenter-Boggs, Lynne; Kang, S.; Zhou, Jizhong; Reganold, John P.

    2010-01-01

    Relationships between soil microbial diversity and soil function are the subject of much debate. Process-level analyses have shown that microbial function varies with soil type and responds to soil management. However, such measurements cannot determine the role of community structure and diversity in soil function. The goal of this study was to investigate the role of gene frequency and diversity, measured by microarray analysis, on soil processes. The study was conducted in an agro-ecosystem characterized by contrasting management practices and soil types. Eight pairs of adjacent commercial organic and conventional strawberry fields were matched for soil type, strawberry variety, and all other environmental conditions. Soil physical, chemical and biological analyses were conducted including functional gene microarrays (FGA). Soil physical and chemical characteristics were primarily determined by soil textural type (coarse vs fine-textured), but biological and FGA measures were more influenced by management (organic vs conventional). Organically managed soils consistently showed greater functional activity as well as FGA signal intensity (SI) and diversity. Overall FGA SI and diversity were correlated to total soil microbial biomass. Functional gene group SI and/or diversity were correlated to related soil chemical and biological measures such as microbial biomass, cellulose, dehydrogenase, ammonium and sulfur. Management was the dominant determinant of soil biology as measured by microbial gene frequency and diversity, which paralleled measured microbial processes.

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

    SciTech Connect

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

    2010-09-30

    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 of nitrogen and phenylacetylene stimulated in situ methane oxidation while minimizing nitrous oxide production. Molecular analyses also indicated that methane-oxidizing bacteria may play a significant role in not only removing methane, but in nitrous oxide production as well, although the contribution of ammonia-oxidizing archaea to nitrous oxide production can not be excluded at this time. Future efforts to control both methane and nitrous oxide emissions from landfills as well as from other environments (e.g., agricultural soils) should consider these issues. Finally, a methanotrophic biofiltration system was designed and modeled for the promotion of methanotrophic activity in local methane 'hotspots' such as landfills. Model results as well as economic analyses of these biofilters indicate that the use of methanotrophic biofilters for controlling methane emissions is technically feasible, and provided either the costs of biofilter construction and operation are reduced or the value of CO{sub 2} credits is increased, can also be economically attractive.

  2. System for the removal of contaminant soil-gas vapors

    DOEpatents

    Weidner, J.R.; Downs, W.C.; Kaser, T.G.; Hall, H.J.

    1997-12-16

    A system extracts contaminated vapors from soil or other subsurface regions by using changes in barometric pressure to operate sensitive check valves that control air entry and removal from wells in the ground. The system creates an efficient subterranean flow of air through a contaminated soil plume and causes final extraction of the contaminants from the soil to ambient air above ground without any external energy sources. 4 figs.

  3. System for the removal of contaminant soil-gas vapors

    DOEpatents

    Weidner, Jerry R.; Downs, Wayne C.; Kaser, Timothy G.; Hall, H. James

    1997-01-01

    A system extracts contaminated vapors from soil or other subsurface regions by using changes in barometric pressure to operate sensitive check valves that control air entry and removal from wells in the ground. The system creates an efficient subterranean flow of air through a contaminated soil plume and causes final extraction of the contaminants from the soil to ambient air above ground without any external energy sources.

  4. The influence of soil gas transport properties on methane oxidation in a selection of northern European soils

    NASA Astrophysics Data System (ADS)

    Ball, B. C.; Smith, K. A.; Klemedtsson, L.; Brumme, R.; Sitaula, B. K.; Hansen, S.; Priemé, A.; MacDonald, J.; Horgan, G. W.

    1997-10-01

    The oxidation of atmospheric methane in soils was measured in situ at a selection of sites in northern Europe, mainly under forest but also under moorland and agricultural arable land and grassland. Our objective was to examine how land use, soil type, and location affected methane oxidation through their impact on gas diffusivity and air permeability. Gas diffusivity at the soil surface and, in some cases, after removal of any surface organic layer was measured in situ using Freon-22 tracer in a portable probe. For about half of the sites, gas diffusivity was also measured in intact topsoil core samples in the laboratory using krypton 85. Air permeability and porosity were also measured on these cores. Although the method of measurement of CH4 oxidation varied between sites, the same techniques were used to measure soil physical properties at all sites. CH4 oxidation rates ranged from 0 to 2.5 mg m-2 d-1. Diffusivity also covered a very wide range, being lowest in loam cores from wet grassland in Norway and highest in relatively dry, sandy soils in Denmark and Scotland. CH4 oxidation tended to increase with gas diffusivity measured in situ at the soil surface, though the relationship was poor at high diffusivities, presumably because CH4 oxidation was not limited by diffusion. Removal of the surface organic layer reduced in situ diffusivity at the surface and improved its relationship with CH4 oxidation rate. Sites where soils had well-developed structure and a loose and permeable organic layer at the surface tended to have the highest CH4 oxidation rates. Core measurements, particularly of air permeability, could not be obtained at some sites owing to the inability to take suitable samples. Diffusivity measured in cores generally decreased with increasing depth of sampling in the topsoil, with the 50-to 100-mm depth giving the best correlation with CH4 uptake; cores from within this layer also gave the highest CH4 oxidation during laboratory incubation. Effective

  5. Greenhouse Gas Fluxes from Forested Wetland and Upland Soils

    NASA Astrophysics Data System (ADS)

    Savage, K. E.; Davidson, E. A.

    2015-12-01

    Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are the most important greenhouse gases. Soils are the dominant natural source of N2O, and have been shown to be a small sink under N-limited conditions. Wetlands are a significant natural source of CH4, and dry upland soils a natural CH4 sink. Soils release CO2 produced by both autotrophic (root) and heterotrophic (microbial) respiration processes. Variation in soil moisture can be very dynamic, and it is one of the dominant factors controlling soil aeration, and hence the balance between aerobic (predominantly CO2 producing) and anaerobic (both CO2 and CH4 producing) respiration. The production and consumption of N2O is also highly dependent on spatial and temporal variation in soil moisture. Howland forest, ME is a mosaic of well drained upland, wetland and small transitional upland/wetland soils which makes for a unique and challenging environment to measure the effects of soil moisture on the net exchange of these important greenhouse gases. To quantify the flux of CO2, CH4 and N2O from the Howland forest soils, we utilized a previously developed automated chamber system for measuring CO2 efflux (Licor 6252 IRGA) from soils, and configured it to run in-line with a new model quantum cascade laser (QCL) system which measures N2O and CH4 (Aerodyne model QC-TILDAS-CS). This system allowed for simultaneous, high frequency, continuous measurement of all three greenhouse gases. Fourteen sampling chambers were deployed in an upland soil (8), nearby wetland (3) and a transitional upland/wetland (3). Each chamber was measured every 90 minutes. Upland soils were consistent sources of CO2 and sinks for CH4, however the N2O fluxes were transient between sources and sinks. The wetland soils were consistent sources of high CH4 emissions, low CO2 emissions and a consistently small N2O sink. The transitional upland/wetland soil was a consistent source of CO2 but was much more transient between CH4 and N2O sources and

  6. The soil moisture active passive experiments (SMAPEx): Towards soil moisture retrieval from the SMAP mission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    NASA’s Soil Moisture Active Passive (SMAP) mission, scheduled for launch in 2014, will carry the first combined L-band radar and radiometer system with the objective of mapping near surface soil moisture and freeze/thaw state globally at near-daily time step (2-3 days). SMAP will provide three soil ...

  7. Use of Flue Gas Desulfurization (FGD) Gypsum as a Heavy Metal Stabilizer in Contaminated Soils

    EPA Science Inventory

    Flue Gas Desulfurization (FGD) gypsum is a synthetic by-product generated from the flue gas desulfurization process in coal power plants. It has several beneficial applications such as an ingredient in cement production, wallboard production and in agricultural practice as a soil...

  8. Hydro-geomechanical behaviour of gas-hydrate bearing soils during gas production through depressurization and CO2 injection

    NASA Astrophysics Data System (ADS)

    Deusner, C.; Gupta, S.; Kossel, E.; Bigalke, N.; Haeckel, M.

    2015-12-01

    Results from recent field trials suggest that natural gas could be produced from marine gas hydrate reservoirs at compatible yields and rates. It appears, from a current perspective, that gas production would essentially be based on depressurization and, when facing suitable conditions, be assisted by local thermal stimulation or gas hydrate conversion after injection of CO2-rich fluids. Both field trials, onshore in the Alaska permafrost and in the Nankai Trough offshore Japan, were accompanied by different technical issues, the most striking problems resulting from un-predicted geomechanical behaviour, sediment destabilization and catastrophic sand production. So far, there is a lack of experimental data which could help to understand relevant mechanisms and triggers for potential soil failure in gas hydrate production, to guide model development for simulation of soil behaviour in large-scale production, and to identify processes which drive or, further, mitigate sand production. We use high-pressure flow-through systems in combination with different online and in situ monitoring tools (e.g. Raman microscopy, MRI) to simulate relevant gas hydrate production scenarios. Key components for soil mechanical studies are triaxial systems with ERT (Electric resistivity tomography) and high-resolution local strain analysis. Sand production control and management is studied in a novel hollow-cylinder-type triaxial setup with a miniaturized borehole which allows fluid and particle transport at different fluid injection and flow conditions. Further, the development of a large-scale high-pressure flow-through triaxial test system equipped with μ-CT is ongoing. We will present results from high-pressure flow-through experiments on gas production through depressurization and injection of CO2-rich fluids. Experimental data are used to develop and parametrize numerical models which can simulate coupled process dynamics during gas-hydrate formation and gas production.

  9. Long-term monitoring of soil gas radon and permeability at two reference sites.

    PubMed

    Chen, Jing; Falcomer, Renato; Ly, Jim; Wierdsma, Jessica; Bergman, Lauren

    2008-01-01

    The long-term monitoring of soil radon variations was conducted at two reference sites in Ottawa. The purpose of this study was to determine whether a single soil radon survey could provide a representative soil radon characteristic of the site. Results showed that during the normal field survey period from June to September in Canada, a single field survey with multiple measurements of soil gas radon concentrations at a depth of 80 cm can characterise the soil radon level of a site within a deviation of +/-30%. Direct in situ soil permeability measurements exhibited, however, large variations even within an area of only 10 x 10 m(2). Considering such large variations and the weight of the equipment, soil permeability can be determined by direct measurements whenever possible or by other qualitative evaluation methods for sites that are hard to access with heavy equipment.

  10. Laboratory and field evaluation of the gas treatment approach for insitu remediation of chromate-contaminated soils

    SciTech Connect

    Thornton, E.C.; Jackson, R.L.

    1994-04-01

    Laboratory scale soil treatment tests have been conducted as part of an effort to develop and implement an in situ chemical treatment approach to the remediation of chromate-contaminated soils through the use of reactive gases. These tests involved three different soil samples that were contaminated with Cr(VI) at the 200 ppM level. Treatment of the contaminated soils was performed by passing 100 ppM and 2000 ppM concentrations of hydrogen sulfide in nitrogen through soil columns until a S:Cr mole ratio of 10:1 was achieved. The treated soils were then leached with groundwater or deionized water and analyzed to assess the extent of chromium immobilization. Test results indicate >90% immobilization of chromium and demonstrate that the treatment process is irreversible. Ongoing developmental efforts are being directed towards the demonstration and evaluation of the gas treatment approach in a field test at a chromate-contaminated site. Major planned activities associated with this demonstration include laboratory testing of waste site soil samples, design of the treatment system and injection/extraction well network, geotechnical and geochemical characterization of the test site, and identification and resolution of regulatory and safety requirements.

  11. Soil features and indoor radon concentration prediction: radon in soil gas, pedology, permeability and 226Ra content.

    PubMed

    Lara, E; Rocha, Z; Santos, T O; Rios, F J; Oliveira, A H

    2015-11-01

    This work aims at relating some physicochemical features of soils and their use as a tool for prediction of indoor radon concentrations of the Metropolitan Region of Belo Horizonte (RMBH), Minas Gerais, Brazil. The measurements of soil gas radon concentrations were performed by using an AlphaGUARD monitor. The (226)Ra content analysis was performed by gamma spectrometry (high pure germanium) and permeabilities were performed by using the RADON-JOK permeameter. The GEORP indicator and soil radon index (RI) were also calculated. Approximately 53 % of the Perferric Red Latosols measurement site could be classified as 'high risk' (Swedish criteria). The Litholic Neosols presented the lowest radon concentration mean in soil gas. The Perferric Red Latosols presented significantly high radon concentration mean in soil gas (60.6 ± 8.7 kBq m(-3)), high indoor radon concentration, high RI, (226)Ra content and GEORP. The preliminary results may indicate an influence of iron formations present very close to the Perferric Red Latosols in the retention of uranium minerals.

  12. Geochemical variation of soil-gas composition for fault trace and earthquake precursory studies along the Hsincheng fault in NW Taiwan.

    PubMed

    Walia, Vivek; Yang, Tsanyao Frank; Hong, Wei-Li; Lin, Shih-Jung; Fu, Ching-Chou; Wen, Kuo-Liang; Chen, Cheng-Hong

    2009-10-01

    The present study is proposed to investigate geochemical variations of soil-gas composition in the vicinity of the geologic fault zone of Hsincheng in the Hsinchu area of Taiwan. Soil-gas surveys have been conducted across the Hsincheng fault, to look for the degassing pattern of this fault system. During the surveys, soil-gas samples were collected along traverses crossing the observed structures. The collected soil-gas samples were analysed for He, Rn, CO(2), CH(4), Ar, O(2) and N(2). The data analysis clearly reveals anomalous values along the fault. Before selecting a monitoring site, the occurrence of deeper gas emanation was investigated by the soil-gas surveys and followed by continuous monitoring of some selected sites with respect to tectonic activity to check the sensitivity of the sites. A site was selected for long term monitoring on the basis of coexistence of high concentration of helium, radon and carrier gases and sensitivity towards the tectonic activity in the region. A continuous monitoring station was established at Hsinchu National Industrial Science Park (HNISP) in October 2005. Preliminary results of the monitoring station have shown possible precursory signals for some earthquake events.

  13. Effects of organic dairy manure amendment on soil phosphatase activities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic dairy production is increasing in the U.S. due to concerns over environmental, human, and animal health. It is well known that the application of livestock manure to soil can influence enzyme activities involved in nutrient cycling and soil fertility, such as soil phosphatases; however, orga...

  14. Variation in Soil Enzyme Activities in a Temperate Agroforestry Watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Integration of agroforestry and grass buffers into row crop watersheds improves overall environmental quality, including soil quality. The objective of this study was to examine management and landscape effects on soil carbon, soil nitrogen, microbial diversity, enzyme activity, and DNA concentrati...

  15. Accommodating Students with Disabilities in Soil Science Activities

    ERIC Educational Resources Information Center

    Langley-Turnbaugh, S. J.; Murphy, Kate; Levin, E.

    2004-01-01

    Soil science education is lacking in terms of accommodations for persons with disabilities. Individuals with disabilities are often excluded from soil science activities in school, and from soil science careers. GLOBE (Global Learning Observations to Benefit the Environment) is a worldwide, hands-on primary and secondary school-based education and…

  16. Soil gas radon assessment and development of a radon risk map in Bolsena, Central Italy.

    PubMed

    Cinelli, G; Tositti, L; Capaccioni, B; Brattich, E; Mostacci, D

    2015-04-01

    Vulsini Volcanic district in Northern Latium (Central Italy) is characterized by high natural radiation background resulting from the high concentrations of uranium, thorium and potassium in the volcanic products. In order to estimate the radon radiation risk, a series of soil gas radon measurements were carried out in Bolsena, the principal urban settlement in this area NE of Rome. Soil gas radon concentration ranges between 7 and 176 kBq/m(3) indicating a large degree of variability in the NORM content and behavior of the parent soil material related in particular to the occurrence of two different lithologies. Soil gas radon mapping confirmed the existence of two different areas: one along the shoreline of the Bolsena lake, characterized by low soil radon level, due to a prevailing alluvial lithology; another close to the Bolsena village with high soil radon level due to the presence of the high radioactive volcanic rocks of the Vulsini volcanic district. Radon risk assessment, based on soil gas radon and permeability data, results in a map where the alluvial area is characterized by a probability to be an area with high Radon Index lower than 20 %, while probabilities higher than 30 % and also above 50 % are found close to the Bolsena village.

  17. Variations in soil N cycling and trace gas emissions in wet tropical forests.

    PubMed

    Holtgrieve, Gordon W; Jewett, Peter K; Matson, Pamela A

    2006-01-01

    We used a previously described precipitation gradient in a tropical montane ecosystem of Hawai'i to evaluate how changes in mean annual precipitation (MAP) affect the processes resulting in the loss of N via trace gases. We evaluated three Hawaiian forests ranging from 2200 to 4050 mm year-1 MAP with constant temperature, parent material, ecosystem age, and vegetation. In situ fluxes of N2O and NO, soil inorganic nitrogen pools (NH4+ and NO3-), net nitrification, and net mineralization were quantified four times over 2 years. In addition, we performed 15N-labeling experiments to partition sources of N2O between nitrification and denitrification, along with assays of nitrification potential and denitrification enzyme activity (DEA). Mean NO and N2O emissions were highest at the mesic end of the gradient (8.7+/-4.6 and 1.1+/-0.3 ng N cm-2 h-1, respectively) and total oxidized N emitted decreased with increased MAP. At the wettest site, mean trace gas fluxes were at or below detection limit (gas flux from soil through soil redox conditions and the supply of electron donors and acceptors.

  18. Improving soil CO2 efflux estimates from in-situ soil CO2 sensors with gas transport measurements

    NASA Astrophysics Data System (ADS)

    Sanchez-Canete, E. P.; Barron-Gafford, G.; Van Haren, J. L. M.; Scott, R. L.

    2015-12-01

    Correctly estimating soil carbon dioxide (CO2) fluxes emitted to the atmosphere is essential because they are a large component of the ecosystem carbon balance. Continuous estimates of soil CO2 flux, especially when paired with eddy covariance measurements of whole-ecosystem CO­2 exchange, help to disaggregate net ecosystem CO2 exchange. Most researchers estimate soil CO2 fluxes by applying the gradient method; however, this is only appropriate in the absence of advective or convective processes. Given the rarity of such static states, we must move toward measurement techniques that will allow us to quantify the dynamic soil efflux system with gas transport by convective, advective and molecular diffusion processes. Convective processes are mainly relevant in caves, where values of relative humidity, temperature and CO2 molar fraction determine the buoyancy of the external-internal air masses. These convective processes also are important in large fractures when temperature differences between surface and depth can generate convection, transporting CO2 from deep layers to the atmosphere. Advective processes occur both in caves and in soils, and the CO2 exchanges are mainly due to three factors: wind, changes in atmospheric pressure, and changes in the water table. Molecular diffusion processes are being widely applied in the determination of soil-atmosphere gas exchanges by applying the gradient method. However, the use of the gradient method can yield inappropriate flux estimates due to the uncertainties mainly associated with the inappropriate determination of the soil diffusion coefficient. Therefore, in-situ methods to determine diffusion coefficient are necessary to obtain accurate CO2 fluxes. If this is resolved, the gradient method has great potential to become the most used technique to monitor atmosphere-soil CO2 exchanges within the next few years. Here we review the state of the science and describe a series of field measurements for significantly

  19. Assessment of soil contamination by (210)Po and (210)Pb around heavy oil and natural gas fired power plants.

    PubMed

    Al-Masri, M S; Haddad, Kh; Doubal, A W; Awad, I; Al-Khatib, Y

    2014-06-01

    Soil contamination by (210)Pb and (210)Po around heavy oil and natural gas power plants has been investigated; fly and bottom ash containing enhanced levels of (210)Pb and (210)Po were found to be the main source of surface soil contamination. The results showed that (210)Pb and (210)Po in fly-ash (economizer, superheater) is highly enriched with (210)Pb and (210)Po, while bottom-ash (boiler) is depleted. The highest (210)Pb and (210)Po activity concentrations were found to be in economizer ash, whereas the lowest activity concentration was in the recirculator ash. On the other hand, (210)Pb and (210)Po activity concentrations in soil samples were found to be higher inside the plant site area than those samples collected from surrounding areas. The highest levels were found in the vicinity of Mhardeh and Tishreen power plants; both plants are operated by heavy oil and natural fuels, while the lowest values were found to be in those samples collected from Nasrieh power plant, which is only operated by one type of fuel, viz. natural gas. In addition, the levels of surface soil contamination have decreased as the distance from the power plant site center increased.

  20. Role of forest soils in the national greenhouse gas inventory

    NASA Astrophysics Data System (ADS)

    Jandl, R.

    2012-12-01

    In Austria the forests are a key category of the GHG budget. The role of forest soils as a sink or source of carbon has so far not been fully assessed and as a default position a stable soil carbon pool was reported. A combination from a modeling exercise and a field survey allowed the scrutinization of this assumption. The field data represent a repeated soil inventory after 20 years. Due to the spatial heterogeneity of chemical soil properties no clear conclusion of the temporal change of soil carbon was made. The data set from the field survey was used for the validation of a modeling exercise. We used the model Yasso07 that is well suited for the available site information in Austria. The measured and the simulated soil carbon change had an acceptable fit. The modeling exercise suggested a statistically insignificant loss of soil carbon during a committment period of the Kyoto Protocol. The standing biomass of the forest is still a carbon sink. Owing to the large forest area this insignificant soil carbon loss strongly reduces the carbon sink strength of the entire forest.

  1. Estimation of mechanical dispersion and dispersivity in a soil-gas system by column experiments and the dusty gas model.

    PubMed

    Hibi, Yoshihiko; Kanou, Yuki; Ohira, Yuki

    2012-04-01

    In a previous study, column experiments were carried out with Toyoura sand (permeability 2.05×10(-11)m(2)) and Toyoura sand mixed with bentonite (permeability 9.96×10(-13)m(2)) to obtain the molecular diffusion coefficient, the Knudsen diffusion coefficient, the tortuosity for the molecular diffusion coefficient, and the mechanical dispersion coefficient of soil-gas systems. In this study, we conducted column experiments with field soil (permeability 2.0×10(-13)m(2)) and showed that the above parameters can be obtained for both less-permeable and more-permeable soils by using the proposed method for obtaining the parameters and performing column experiments. We then estimated dispersivity from the mechanical dispersion coefficients obtained by the column experiments. We found that the dispersivity depended on the mole fraction of the tracer gas and could be represented by a quadratic equation.

  2. Soil greenhouse gas emissions reduce the contribution of mangrove plants to the atmospheric cooling effect

    NASA Astrophysics Data System (ADS)

    Chen, Guangcheng; Chen, Bin; Yu, Dan; Tam, Nora F. Y.; Ye, Yong; Chen, Shunyang

    2016-12-01

    Mangrove soils have been recognized as sources of greenhouse gases, but the atmospheric fluxes are poorly characterized, and their adverse warming effect has rarely been considered with respect to the potential contribution of mangrove wetlands to climate change mitigation. The current study balanced the warming effect of soil greenhouse gas emissions with the plant carbon dioxide (CO2) sequestration rate derived from the plants’ net primary production in a productive mangrove wetland in South China to assess the role of mangrove wetlands in reducing the atmospheric warming effect. Soil characteristics were also studied in the summer to examine their relationships with gas fluxes. The soil to atmosphere fluxes of nitrous oxide (N2O), methane (CH4) and CO2 ranged from -1.6 to 50.0 μg m-2 h-1, from -1.4 to 5360.1 μg m-2 h-1 and from -31 to 512 mg m-2 h-1, respectively, which indicated that the mangrove soils act as sources of greenhouse gases in this area. The gas fluxes were higher in summer than in the cold seasons and were variable across mangrove sites. Gas fluxes in summer were positively correlated with the soil organic carbon, total nitrogen, and ammonia contents. The mangrove plants sequestered a considerable amount of atmospheric CO2 at rates varying from 3652 to 7420 g CO2 m-2 yr-1. The ecosystem acted as a source of CH4 and N2O gases but was a more intense CO2 sink. However, the warming effect of soil gas emissions accounted for 9.3-32.7% of the plant CO2 sequestration rate, partially reducing the benefit of mangrove plants, and the two trace gases comprised 9.7-33.2% of the total warming effect. We therefore propose that an assessment of the reduction of atmospheric warming effects by a mangrove ecosystem should consider both soil greenhouse gas emissions and plant CO2 sequestration.

  3. Measurement of helium isotopes in soil gas as an indicator of tritium groundwater contamination.

    PubMed

    Olsen, Khris B; Dresel, P Evan; Evans, John C; McMahon, William J; Poreda, Robert

    2006-05-01

    The focus of this study was to define the shape and extent of tritium groundwater contamination emanating from a legacy burial ground and to identify vadose zone sources of tritium using helium isotopes (3He and 4He) in soil gas. Helium isotopes were measured in soil-gas samples collected from 70 sampling points around the perimeter and downgradient of a burial ground that contains buried radioactive solid waste. The soil-gas samples were analyzed for helium isotopes using rare gas mass spectrometry. 3He/4He ratios, reported as normalized to the air ratio (RA), were used to locate the tritium groundwater plume emanating from the burial ground. The 3He (excess) suggested that the general location of the tritium source is within the burial ground. This study clearly demonstrated the efficacy of the 3He method for application to similar sites elsewhere within the DOE weapons complex.

  4. Effects of soil rewetting and thawing on soil gas fluxes: a review of current literature and suggestions for future research

    SciTech Connect

    Kim, Dong-Gill; Vargas, Rodrigo; Bond-Lamberty, Benjamin; Turetsky, Merritt

    2012-07-09

    Rewetting of dry soils and thawing of frozen soils are short-term, transitional phenomena in terms of hydrology and thermodynamics in soil systems. The impact of these short-term phenomena on larger-scale ecosystem fluxes has only recently been fully appreciated, and a growing number of studies show that these events affect various biogeochemical processes including fluxes of biogenic gases such as carbon dioxide (CO{sub 2}), methane (CH{sub 4}), nitrous oxide (N{sub 2}O), ammonia (NH{sub 3}) and nitric oxide (NO). Global climate models predict that future climatic change is likely to alter the frequency and intensity of drying-rewetting events and thawing of frozen soils, highlighting the importance of understanding how rewetting and thawing will influence biogenic gas fluxes. Here we summarize findings in an acquired database from 338 studies conducted from 1956-2010, and propose future research questions. Studies have reported conflicting results, ranging from large increases in gas fluxes to non-significant changes following rewetting and thawing in various terrestrial ecosystems. An analysis of published data revealed that CO{sub 2}, CH{sub 4}, N{sub 2}O, NO and NH{sub 3} fluxes increase 7.6 (standard error 1.1) times following rewetting and thawing with no significant difference between these events. We explore possible mechanisms and controls that regulate flux responses, and note that there is a lack of studies on variation of CH{sub 4}, NO and NH{sub 3} fluxes following rewetting and thawing events. High temporal resolution of flux measurements is critical to capture rapid changes in the gas fluxes after these soil perturbations. Finally, we propose that future studies should investigate the interactions between biological (i.e., microbial community) and physical (i.e., gas production, flux, and dissolution) changes in biogenic gas fluxes, and explore synergistic experimental and modelling approaches.

  5. Impacts of prescribed burning on soil greenhouse gas fluxes in a suburban native forest of south-eastern Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Wang, Y. Z.; Xu, Z. H.; Fu, L.

    2015-11-01

    activities, following the prescribed burning, were the factors that controlled the greenhouse gas exchanges. Our results suggested that the low-intensity prescribed burning would decrease soil CO2 emission and increase CH4 uptake, but this effect would be present within a relatively short period. Only slight changes in the surface soil properties during the combustion and very limited impacts of prescribed burning on the mineral soils supported the rapid recovery of the greenhouse gas exchange rates.

  6. Impacts of prescribed burning on soil greenhouse gas fluxes in a suburban native forest of south-eastern Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Wang, Y. Z.; Xu, Z. H.; Fu, L.

    2015-07-01

    Prescribed burning is a forest management practice that is widely used in Australia to reduce the risk of damaging wildfires. It can affect both carbon (C) and nitrogen (N) cycling in the forest and thereby influence the soil-atmosphere exchange of major greenhouse gases, i.e. carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). To quantify the impact of a prescribed burning (conducted on 27 May 2014) on greenhouse gas exchange and the potential controlling mechanisms, we carried out a series of field measurements before (August 2013) and after (August 2014 and November 2014) the fire. Gas exchange rates were determined at 4 replicate sites which were burned during the combustion and another 4 adjacent unburned sites located in green islands, using a set of static chambers. Surface soil properties including temperature, pH, moisture, soil C and N pools were also determined either by in situ measurement or by analysing surface 10 cm soil samples. All of the chamber measurements indicated a net sink of atmospheric CH4, with mean CH4 uptake ranging from 1.15 to 1.99 mg m-2 day-1. The burning significantly enhanced CH4 uptake as indicated by the significant higher CH4 uptake rates at the burned sites measured in August 2014. While within the next 3 months the CH4 uptake rate was recovered to pre-burning levels. Mean CO2 emission from forest soils ranged from 2721.76 to 7113.49 mg m-2 day-1. The effect of prescribed burning on CO2 emission was limited within the first 3 months, as no significant difference was observed between the burned and the adjacent unburned sites in both August and November 2014. The temporal dynamics of the CO2 emission presented more seasonal variations, rather than burning effects. The N2O emission at the studied sites was quite low, and no significant impact of burning was observed. The changes in understory plants and litter layers, surface soil temperature, C and N substrate availability and microbial activities, resulting from the

  7. The effect of compost on carbon cycling and the active soil microbiota

    SciTech Connect

    Singer, Esther; Woyke, Tanja; Ryals, Rebecca; Silver, Whendee

    2014-09-02

    Rangelands cover an estimated 40-70percent of global landmass, approximately one-third of the landmass of the United States and half of California. The soils of this vast land area has high carbon (C) storage capacity, which makes it an important target ecosystem for the mitigation of greenhouse gas emission and effects on climate change, in particular under land management techniques that favor increased C sequestration rates. While microbial communities are key players in the processes responsible for C storage and loss in soils, we have barely shed light on these highly complex processes in part due to the tremendous and seemingly intractable diversity of microbes, largely uncultured, that inhabit soil ecosystems. In our study, we compare Mediterranean grassland soil plots that were amended with greenwaste compost in a single event 6 years ago. Subsampling of control and amended plots was performed in depth increments of 0-10 cm. We present data on greenhouse gas emissions and budgets of carbon, nitrogen, phosphorus, and micronutrients in dependence of compost amendment. Changes in the active members of the soil microbial community were assessed using a novel approach combining flow cytometry and 16S tag sequencing disclosing who is active. This is the first study revealing the nature of actively metabolizing microbial community members linked to the geochemical characteristics of compost-amended soil.

  8. Response of soil microbial activity and biodiversity in soils polluted with different concentrations of cypermethrin insecticide.

    PubMed

    Tejada, Manuel; García, Carlos; Hernández, Teresa; Gómez, Isidoro

    2015-07-01

    We performed a laboratory study into the effect of cypermethrin insecticide applied to different concentrations on biological properties in two soils [Typic Xerofluvent (soil A) and Xerollic Calciorthid (soil B)]. Two kg of each soil were polluted with cypermethrin at a rate of 60, 300, 600, and 1,200 g ha(-1) (C1, C2, C3, and C4 treatments). A nonpolluted soil was used as a control (C0 treatment). For all treatments and each experimental soil, soil dehydrogenase, urease, β-glucosidase, phosphatase, and arylsulphatase activities and soil microbial community were analysed by phospholipid fatty acids, which were measured at six incubation times (3, 7, 15, 30, 60, and 90 days). The behavior of the enzymatic activities and microbial population were dependent on the dose of insecticide applied to the soil. Compared with the C0 treatment, in soil A, the maximum inhibition of the enzymatic activities was at 15, 30, 45, and 90 days for the C1, C2, C3, and C4 treatments, respectively. However, in soil B, the maximum inhibition occurred at 7, 15, 30, and 45 days for the C1, C2, C3, and C4 treatments, respectively. These results suggest that the cypermethrin insecticide caused a negative effect on soil enzymatic activities and microbial diversity. This negative impact was greater when a greater dose of insecticide was used; this impact was also greater in soil with lower organic matter content. For both soils, and from these respective days onward, the enzymatic activities and microbial populations progressively increased by the end of the experimental period. This is possibly due to the fact that the insecticide or its breakdown products and killed microbial cells, subsequently killed by the insecticide, are being used as a source of energy or as a carbon source for the surviving microorganisms for cell proliferation.

  9. Soil carbon sequestration in semi-arid soil through the addition of fuel gas desulfurization gypsum (FGDG)

    NASA Astrophysics Data System (ADS)

    Han, Young-Soo; Tokunaga, Tetsu; Oh, Chamteut

    2014-05-01

    This study investigated a new strategy for increasing carbon retention in slightly alkaline soils through addition of fuel gas desulfurization gypsum (FGDG, CaSO4•2H2O). FGDG is moderately soluble and thus the FGDG amendment may be effective to reduce microbial respiration, to accelerate calcite (CaCO3) precipitation, and to promote soil organic carbon (SOC) complexation on mineral surfaces, but rates of these processes need to be understood. The effects of FGDG addition were tested in laboratory soil columns with and without FGDG-amended layers, and in greenhouse soil columns planted with switchgrass, a biofuel crop. The results of laboratory column experiments demonstrated that additions of FGDG promote soil carbon sequestration through suppressing microbial respiration to the extent of ~200 g per m2 soil per m of supplied water, and promoting calcite precipitation at similar rates. The greenhouse experiments showed that the FGDG treatments did not adversely affect biomass yield (~600 g dry biomass/m2/harvest) at the higher irrigation rate (50 cm/year), but substantially reduced recoverable biomass under the more water-limited conditions (irrigation rate = 20 cm/year). The main achievements of this study are (1) the identification of conditions in which inorganic and organic carbon sequestration is practical in semi-arid and arid soils, (2) development of a method for measuring the total carbon balance in unsaturated soil columns, and (3) the quantification of different pathways for soil carbon sequestration in response to FGDG amendments. These findings provide information for evaluating land use practices for increased soil carbon sequestration under semi-arid region biofuel crop production.

  10. Biochar and N fertilizer alters soil N dynamics and greenhouse gas fluxes from two temperate soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar is a high surface-area, variable-charge organic material that may improve nutrient retention and soil C sequestration but its general beneficial properties have yet to be quantified in many soil types. Biochar has the potential to increase soil water-holding capacity, cation exchange capacit...

  11. Influence of Flue Gas Desulfurization Gypsum Amendments on Heavy Metal Distribution in Reclaimed Sodic Soils

    PubMed Central

    Chen, Qun; Wang, Shujuan; Li, Yan; Zhang, Ning; Zhao, Bo; Zhuo, Yuqun; Chen, Changhe

    2015-01-01

    Abstract Although flue gas desulfurization (FGD) gypsum has become an effective soil amendment for sodic soil reclamation, it carries extra heavy metal contamination into the soil environment. The fate of heavy metals introduced by FGD gypsum in sodic or saline–alkali soils is still unclear. This work aims to investigate the effects of FGD gypsum addition on the heavy metal distributions in a sodic soil. Original soil samples were collected from typical sodic land in north China. Soil column leaching tests were conducted to investigate the influence of FGD gypsum addition on the soil properties, especially on distribution profiles of the heavy metals (Pb, Cd, Cr, As, and Hg) in the soil layers. Results showed that pH, electrical conductivity, and exchangeable sodium percentage in amended soils were significantly reduced from 10.2 to 8.46, 1.8 to 0.2 dS/m, and 18.14% to 1.28%, respectively. As and Hg concentrations in the soils were found to be positively correlated with FGD gypsum added. The amount of Hg in the leachate was positively correlated with FGD gypsum application ratio, whereas a negative correlation was observed between the Pb concentration in the leachate and the FGD gypsum ratio. Results revealed that heavy metal concentrations in soils complied well with Environmental Quality Standard for Soils in China (GB15618-1995). This work helps to understand the fate of FGD gypsum-introduced heavy metals in sodic soils and provides a baseline for further environmental risk assessment associated with applying FGD gypsum for sodic soil remediation. PMID:26064038

  12. Measurement of air and VOC vapor fluxes during gas-driven soil remediation: bench-scale experiments.

    PubMed

    Kim, Heonki; Kim, Taeyun; Shin, Seungyeop; Annable, Michael D

    2012-09-04

    In this laboratory study, an experimental method was developed for the quantitative analyses of gas fluxes in soil during advective air flow. One-dimensional column and two- and three-dimensional flow chamber models were used in this study. For the air flux measurement, n-octane vapor was used as a tracer, and it was introduced in the air flow entering the physical models. The tracer (n-octane) in the gas effluent from the models was captured for a finite period of time using a pack of activated carbon, which then was analyzed for the mass of n-octane. The air flux was calculated based on the mass of n-octane captured by the activated carbon and the inflow concentration. The measured air fluxes are in good agreement with the actual values for one- and two-dimensional model experiments. Using both the two- and three-dimensional models, the distribution of the air flux at the soil surface was measured. The distribution of the air flux was found to be affected by the depth of the saturated zone. The flux and flux distribution of a volatile contaminant (perchloroethene) was also measured by using the two-dimensional model. Quantitative information of both air and contaminant flux may be very beneficial for analyzing the performance of gas-driven subsurface remediation processes including soil vapor extraction and air sparging.

  13. Diversity and activity of denitrifiers of chilean arid soil ecosystems.

    PubMed

    Orlando, Julieta; Carú, Margarita; Pommerenke, Bianca; Braker, Gesche

    2012-01-01

    The Chilean sclerophyllous matorral is a Mediterranean semiarid ecosystem affected by erosion, with low soil fertility, and limited by nitrogen. However, limitation of resources is even more severe for desert soils such as from the Atacama Desert, one of the most extreme arid deserts on Earth. Topsoil organic matter, nitrogen and moisture content were significantly higher in the semiarid soil compared to the desert soil. Although the most significant loss of biologically preferred nitrogen from terrestrial ecosystems occurs via denitrification, virtually nothing is known on the activity and composition of denitrifier communities thriving in arid soils. In this study we explored denitrifier communities from two soils with profoundly distinct edaphic factors. While denitrification activity in the desert soil was below detection limit, the semiarid soil sustained denitrification activity. To elucidate the genetic potential of the soils to sustain denitrification processes we performed community analysis of denitrifiers based on nitrite reductase (nirK and nirS) genes as functional marker genes for this physiological group. Presence of nirK-type denitrifiers in both soils was demonstrated but failure to amplify nirS from the desert soil suggests very low abundance of nirS-type denitrifiers shedding light on the lack of denitrification activity. Phylogenetic analysis showed a very low diversity of nirK with only three distinct genotypes in the desert soil which conditions presumably exert a high selection pressure. While nirK diversity was also limited to only few, albeit distinct genotypes, the semiarid matorral soil showed a surprisingly broad genetic variability of the nirS gene. The Chilean matorral is a shrub land plant community which form vegetational patches stabilizing the soil and increasing its nitrogen and carbon content. These islands of fertility may sustain the development and activity of the overall microbial community and of denitrifiers in particular.

  14. Diversity and Activity of Denitrifiers of Chilean Arid Soil Ecosystems

    PubMed Central

    Orlando, Julieta; Carú, Margarita; Pommerenke, Bianca; Braker, Gesche

    2012-01-01

    The Chilean sclerophyllous matorral is a Mediterranean semiarid ecosystem affected by erosion, with low soil fertility, and limited by nitrogen. However, limitation of resources is even more severe for desert soils such as from the Atacama Desert, one of the most extreme arid deserts on Earth. Topsoil organic matter, nitrogen and moisture content were significantly higher in the semiarid soil compared to the desert soil. Although the most significant loss of biologically preferred nitrogen from terrestrial ecosystems occurs via denitrification, virtually nothing is known on the activity and composition of denitrifier communities thriving in arid soils. In this study we explored denitrifier communities from two soils with profoundly distinct edaphic factors. While denitrification activity in the desert soil was below detection limit, the semiarid soil sustained denitrification activity. To elucidate the genetic potential of the soils to sustain denitrification processes we performed community analysis of denitrifiers based on nitrite reductase (nirK and nirS) genes as functional marker genes for this physiological group. Presence of nirK-type denitrifiers in both soils was demonstrated but failure to amplify nirS from the desert soil suggests very low abundance of nirS-type denitrifiers shedding light on the lack of denitrification activity. Phylogenetic analysis showed a very low diversity of nirK with only three distinct genotypes in the desert soil which conditions presumably exert a high selection pressure. While nirK diversity was also limited to only few, albeit distinct genotypes, the semiarid matorral soil showed a surprisingly broad genetic variability of the nirS gene. The Chilean matorral is a shrub land plant community which form vegetational patches stabilizing the soil and increasing its nitrogen and carbon content. These islands of fertility may sustain the development and activity of the overall microbial community and of denitrifiers in particular

  15. Effectiveness of compacted soil liner as a gas barrier layer in the landfill final cover system.

    PubMed

    Moon, Seheum; Nam, Kyoungphile; Kim, Jae Young; Hwan, Shim Kyu; Chung, Moonkyung

    2008-01-01

    A compacted soil liner (CSL) has been widely used as a single barrier layer or a part of composite barrier layer in the landfill final cover system to prevent water infiltration into solid wastes for its acceptable hydraulic permeability. This study was conducted to test whether the CSL was also effective in prohibiting landfill gas emissions. For this purpose, three different compaction methods (i.e., reduced, standard, and modified Proctor methods) were used to prepare the soil specimens, with nitrogen as gas, and with water and heptane as liquid permeants. Measured gas permeability ranged from 2.03 x 10(-10) to 4.96 x 10(-9) cm(2), which was a magnitude of two or three orders greater than hydraulic permeability (9.60 x 10(-13) to 1.05 x 10(-11) cm(2)). The difference between gas and hydraulic permeabilities can be explained by gas slippage, which makes gas more permeable, and by soil-water interaction, which impedes water flow and then makes water less permeable. This explanation was also supported by the result that a liquid permeability measured with heptane as a non-polar liquid was similar to the intrinsic gas permeability. The data demonstrate that hydraulic requirement for the CSL is not enough to control the gas emissions from a landfill.

  16. Biological degradation of selected hydrocarbons in an old PAH/creosote contaminated soil from a gas work site.

    PubMed

    Eriksson, M; Dalhammar, G; Borg-Karlson, A K

    2000-05-01

    An old PAH/creosote contaminated soil (total approximately 300 microg PAH/g soil) from a former gas work site in Stockholm, Sweden, has been treated at 20 degrees C with the addition of various nutrients and inoculated with bacteria (isolated from the soil) to enhance the degradation of selected hydrocarbons. Microcosm studies showed that the soil consisted of two contaminant fractions: one available, easily degraded fraction and a strongly sorbed, recalcitrant one. The bioavailable fraction, monitored by headspace solid phase microextraction, contained aromatics with up to three rings, and these were degraded within 20 days down to non-detectable levels (ng PAH/g soil) by both the indigenous bacteria and the externally inoculated samples. The nutrient additives were: a minimal medium (Bushnell-Haas), nitrate, nitrite, potting soil (Anglamark, Sweden), sterile water and aeration with Bushnell-Haas medium. After 30 days treatment most of the sorbed fractions were still present in the soil. Stirring or mechanical mixing of the soil slurries had the greatest effect on degradation, indicating that the substances were too strongly sorbed for the microorganisms. When stirring the choice of nutrient seemed less important. For the non-stirred samples the addition of nitrate with the bacterial inoculum showed the best degradation, compared to the other non-stirred samples. At the end of the experiments, accumulations of metabolites/degradation products, such as 9H-fluorenone, 4-hydroxy-9H-fluorenone, 9,10-phenanthrenedione and 4H-cyclopenta[def]phenanthrenone were detected. The metabolite 4-hydroxy-9H-fluorenone increased by several orders of magnitude during the biological treatments. Microbial activity in the soil was measured by oxygen consumption and carbon dioxide production.

  17. Response of Soil Biogeochemistry to Freeze-thaw Cycles: Impacts on Greenhouse Gas Emission and Nutrient Fluxes

    NASA Astrophysics Data System (ADS)

    Rezanezhad, F.; Parsons, C. T.; Smeaton, C. M.; Van Cappellen, P.

    2014-12-01

    Freeze-thaw is an abiotic stress applied to soils and is a natural process at medium to high latitudes. Freezing and thawing processes influence not only the physical properties of soil, but also the metabolic activity of soil microorganisms. Fungi and bacteria play a crucial role in soil organic matter degradation and the production of greenhouse gases (GHG) such as CO2, CH4 and N2O. Production and consumption of these atmospheric trace gases are the result of biological processes such as photosynthesis, aerobic respiration (CO2), methanogenesis, methanotrophy (CH4), nitrification and denitrification (N2O). To enhance our understanding of the effects of freeze-thaw cycles on soil biogeochemical transformations and fluxes, a highly instrumented soil column experiment was designed to realistically simulate freeze-thaw dynamics under controlled conditions. Pore waters collected periodically from different depths of the column and solid-phase analyses on core material obtained at the initial and end of the experiment highlighted striking geochemical cycling. CO2, CH4 and N2O production at different depths within the column were quantified from dissolved gas concentrations in pore water. Subsequent emissions from the soil surface were determined by direct measurement in the head space. Pulsed CO2 emission to the headspace was observed at the onset of thawing, however, the magnitude of the pulse decreased with each subsequent freeze-thaw cycle indicating depletion of a "freeze-thaw accessible" carbon pool. Pulsed CO2 emission was due to a combination of physical release of gases dissolved in porewater and entrapped below the frozen zone and changing microbial respiration in response to electron acceptor variability (O2, NO3-, SO42-). In this presentation, we focus on soil-specific physical, chemical, microbial factors (e.g. redox conditions, respiration, fermentation) and the mechanisms that drive GHG emission and nutrient cycling in soils under freeze-thaw cycles.

  18. Oxygen transport from the atmosphere to soil gas beneath a slab-on-grade foundation overlying petroleum-impacted soil.

    PubMed

    Lundegard, Paul D; Johnson, Paul C; Dahlen, Paul

    2008-08-01

    Modeling and field study results suggest that, in the case of a building overlying an aerobically biodegradable vapor source (i.e., petroleum-impacted soil), the significance of vapor intrusion into the building depends on the source vapor concentration, the relative position of the vapor source and building, and the rate of O2 transport from the atmosphere to the soil gas beneath the building. This work quantified the latter at a house having about a 250 m2 slab-on-grade foundation footprint. It was constructed on 1.5 m of clean fill overlying a petroleum hydrocarbon-impacted soil layer undergoing methanogenesis. Soil gas O2 and CH4 profiles adjacent to and beneath the foundation were measured and then the soil gas beneath the slab was rapidly displaced with N2. The natural replenishment of O2 was monitored for 90 days using in situ O2 sensors, and the responses with time were similar, independent of location. The O2 replenishment rate was about 2500 g-O2/d immediately after the N2 flood and then it declined to 200-500 g-O2/d over 30 days. Weather events affected the O2 replenishment rate; an increase occurred during a strong wind period (> 3 m/s), and a decrease occurred during a heavy rainfall event. The spatial and temporal patterns in the O2 sensor responses and quantified O2 replenishment rates could not be accounted for by simple mechanistic hypotheses involving lateral diffusion or advection through the bulk soil, and instead the data suggest rapid replenishment immediately below the foundation followed by downward diffusion.

  19. [Effect of fertilization levels on soil microorganism amount and soil enzyme activities].

    PubMed

    Wang, Wei-Ling; Du, Jun-Bo; Xu, Fu-Li; Zhang, Xiao-Hu

    2013-11-01

    Field experiments were conducted in Shangluo pharmaceutical base in Shaanxi province to study the effect of nitrogen, phosphorus and potassium in different fertilization levels on Platycodon grandiflorum soil microorganism and activities of soil enzyme, using three-factor D-saturation optimal design with random block design. The results showed that N0P2K2, N2P2K0, N3P1K3 and N3P3K1 increased the amount of bacteria in 0-20 cm of soil compared with N0P0K0 by 144.34%, 39.25%, 37.17%, 53.58%, respectively. The amount of bacteria in 2040 cm of soil of N3P1K3 increased by 163.77%, N0P0K3 increased the amount of soil actinomycetes significantly by 192.11%, while other treatments had no significant effect. N2P0K2 and N3P1K3 increased the amounts of fungus significantly in 0-20 cm of soil compared with N0P0K0, increased by 35.27% and 92.21%, respectively. N3P0K0 increased the amounts of fungus significantly in 20-40 cm of soil by 165.35%, while other treatments had no significant effect. All treatments decrease soil catalase activity significantly in 0-20 cm of soil except for N2P0K2, and while N2P2K0 and NPK increased catalase activity significantly in 2040 cm of soil. Fertilization regime increased invertase activity significantly in 2040 cm of soil, and decreased phosphatase activity inordinately in 0-20 cm of soil, while increased phosphatase activity in 2040 cm of soil other than N1P3K3. N3P0K0, N0P0K3, N2P0K2, N2P2K0 and NPK increased soil urease activity significantly in 0-20 cm of soil compared with N0P0K0 by 18.22%, 14.87%,17.84%, 27.88%, 24.54%, respectively. Fertilization regime increased soil urease activity significantly in 2040 cm of soil other than N0P2K2.

  20. Nitrogen availability and indirect measurements of greenhouse gas emissions from aerobic and anaerobic biowaste digestates applied to agricultural soils

    SciTech Connect

    Rigby, H.; Smith, S.R.

    2013-12-15

    , indicating greater microbial activity in amended soil and reflecting the lower stability of this OM source, compared to the other, anaerobic digestate types, which showed no consistent effects on MBN compared to the control. Thus, the overall net release of digestate N in different soil types was not regulated by N transfer into the soil microbial biomass, but was determined primarily by digestate properties and the capacity of the soil type to process and turnover digestate N. In contrast to the sandy soil types, where nitrate (NO{sub 3}{sup -}) concentrations increased during incubation, there was an absence of NO{sub 3}{sup -} accumulation in the silty clay soil amended with LTAD and DMADMSW. This provided indirect evidence for denitrification activity and the gaseous loss of N, and the associated increased risk of greenhouse gas emissions under certain conditions of labile C supply and/or digestate physical structure in fine-textured soil types. The significance and influence of the interaction between soil type and digestate stability and physical properties on denitrification processes in digestate-amended soils require urgent investigation to ensure management practices are appropriate to minimise greenhouse gas emissions from land applied biowastes.

  1. The Soil Moisture Active Passive (SMAP) Applications Activity

    NASA Technical Reports Server (NTRS)

    Brown, Molly E.; Moran, Susan; Escobar, Vanessa; Entekhabi, Dara; O'Neill, Peggy; Njoku, Eni

    2011-01-01

    The Soil Moisture Active Passive (SMAP) mission is one of the first-tier satellite missions recommended by the U.S. National Research Council Committee on Earth Science and Applications from Space. The SMAP mission 1 is under development by NASA and is scheduled for launch late in 2014. The SMAP measurements will allow global and high-resolution mapping of soil moisture and its freeze/thaw state at resolutions from 3-40 km. These measurements will have high value for a wide range of environmental applications that underpin many weather-related decisions including drought and flood guidance, agricultural productivity estimation, weather forecasting, climate predictions, and human health risk. In 2007, NASA was tasked by The National Academies to ensure that emerging scientific knowledge is actively applied to obtain societal benefits by broadening community participation and improving means for use of information. SMAP is one of the first missions to come out of this new charge, and its Applications Plan forms the basis for ensuring its commitment to its users. The purpose of this paper is to outline the methods and approaches of the SMAP applications activity, which is designed to increase and sustain the interaction between users and scientists involved in mission development.

  2. Assessment of soil-gas contamination at three former fuel-dispensing sites, Fort Gordon, Georgia, 2010—2011

    USGS Publications Warehouse

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

    2012-01-01

    Soil gas was assessed for contaminants at three former fuel-dispensing sites at Fort Gordon, Georgia, from October 2010 to September 2011. The assessment included delineation of organic contaminants using soil-gas samplers collected from the former fuel-dispensing sites at 8th Street, Chamberlain Avenue, and 12th Street. This assessment was conducted to provide environmental contamination data to Fort Gordon personnel pursuant to requirements for the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Soil-gas samplers installed and retrieved during June and August 2011 at the 8th Street site had detections above the method detection level (MDL) for the mass of total petroleum hydrocarbons (TPH), benzene, toluene, ortho-xylene, undecane, tridecane, pentadecane, and chloroform. Total petroleum hydrocarbons soil-gas mass exceeded the MDL of 0.02 microgram in 54 of the 55 soil-gas samplers. The highest detection of TPH soil-gas mass was 146.10 micrograms, located in the central part of the site. Benzene mass exceeded the MDL of 0.01 microgram in 23 soil-gas samplers, whereas toluene was detected in only 10 soil-gas samplers. Ortho-xylene was detected above the MDL in only one soil-gas sampler. The highest soil-gas mass detected for undecane, tridecane, and pentadecane was located in the northeastern corner of the 8th Street site. Chloroform mass greater than the MDL of 0.01 microgram was detected in less than one-third of the soil-gas samplers. Soil-gas masses above the MDL were identified for TPH, gasoline-related compounds, diesel-range alkanes, trimethylbenzenes, naphthalene, 2-methyl-napthalene, octane, and tetrachloroethylene for the July 2011 soil-gas survey at the Chamberlain Avenue site. All 30 of the soil-gas samplers contained TPH mass above the MDL. The highest detection of TPH mass, 426.36 micrograms, was for a soil-gas sampler located near the northern boundary of the site. Gasoline-related compounds and diesel-range alkanes were

  3. Edaphic factors controlling summer (rainy season) greenhouse gas emissions (CO2 and CH4) from semiarid mangrove soils (NE-Brazil).

    PubMed

    Nóbrega, Gabriel N; Ferreira, Tiago O; Siqueira Neto, M; Queiroz, Hermano M; Artur, Adriana G; Mendonça, Eduardo De S; Silva, Ebenezer De O; Otero, Xosé L

    2016-01-15

    The soil attributes controlling the CO2, and CH4 emissions were assessed in semiarid mangrove soils (NE-Brazil) under different anthropogenic activities. Soil samples were collected from different mangroves under different anthropogenic impacts, e.g., shrimp farming (Jaguaribe River); urban wastes (Cocó River) and a control site (Timonha River). The sites were characterized according to the sand content; physicochemical parameters (Eh and pH); total organic C; soil C stock (SCS) and equivalent SCS (SCSEQV); total P and N; dissolved organic C (DOC); and the degree of pyritization (DOP). The CO2 and CH4 fluxes from the soils were assessed using static closed chambers. Higher DOC and SCS and the lowest DOP promote greater CO2 emission. The CH4 flux was only observed at Jaguaribe which presented higher DOP, compared to that found in mangroves from humid tropical climates. Semiarid mangrove soils cannot be characterized as important greenhouse gas sources, compared to humid tropical mangroves.

  4. Mercury in soil gas and air--A potential tool in mineral exploration

    USGS Publications Warehouse

    McCarthy, Joseph Howard; Vaughn, W.W.; Learned, R.E.; Meuschke, J.L.

    1969-01-01

    The mercury content in soil gas and in the atmosphere was measured in several mining districts to test the possibility that the mercury content in the atmosphere is higher over ore deposits than over barren ground. At Cortez, Nev., the distribution of anorhalous amounts of mercury in the air collected at ground level (soil gas) correlates well with the distribution of gold-bearing rocks that are covered by as much as 100 feet of gravel. The mercury content in the atmosphere collected at an altitude of 200 feet by an aircraft was 20 times background over a mercury posit and 10 times background over two porphyry copper deposits. Measurement of mercury in soil gas and air may prove to be a valuable exploration tool.

  5. Field evaluation of the effects of water table fluctuations on soil radon gas emanations.

    PubMed

    Mose, Douglas G; Merolla, Paul; Mushrush, George W

    2008-07-15

    Measurements of the depth of the water table and the concentration of soil gas radon at water wells in Virginia and Maryland show that at each well site, there is no correlation between the depths of the water table and the radon concentration. However, when comparing nearby water wells, there is a relationship between depth of the water table and the concentration of soil gas radon. Wells with a shallower water table tend to have less soil gas radon emanation. It may be that this relationship It may be that this relationship (higher water table with lower radon emanation) may explain seasonal changes in radon concentration, since changes in water table depth are caused by seasonal changes in precipitation.

  6. Effects of organic carbon sequestration strategies on soil enzymatic activities

    NASA Astrophysics Data System (ADS)

    Puglisi, E.; Suciu, N.; Botteri, L.; Ferrari, T.; Coppolecchia, D.; Trevisan, M.; Piccolo, A.

    2009-04-01

    Greenhouse gases emissions can be counterbalanced with proper agronomical strategies aimed at sequestering carbon in soils. These strategies must be tested not only for their ability in reducing carbon dioxide emissions, but also for their impact on soil quality: enzymatic activities are related to main soil ecological quality, and can be used as early and sensitive indicators of alteration events. Three different strategies for soil carbon sequestration were studied: minimum tillage, protection of biodegradable organic fraction by compost amendment and oxidative polimerization of soil organic matter catalyzed by biometic porfirins. All strategies were compared with a traditional agricultural management based on tillage and mineral fertilization. Experiments were carried out in three Italian soils from different pedo-climatic regions located respectively in Piacenza, Turin and Naples and cultivated with maize or wheat. Soil samples were taken for three consecutive years after harvest and analyzed for their content in phosphates, ß-glucosidase, urease and invertase. An alteration index based on these enzymatic activities levels was applied as well. The biomimetic porfirin application didn't cause changes in enzymatic activities compared to the control at any treatment or location. Enzymatic activities were generally higher in the minimum tillage and compost treatment, while differences between location and date of samplings were limited. Application of the soil alteration index based on enzymatic activities showed that soils treated with compost or subjected to minimum tillage generally have a higher biological quality. The work confirms the environmental sustainability of the carbon sequestering agronomical practices studied.

  7. Radon in Soil Gas Above Bedrock Fracture Sets at the Shepley’s Hill Superfund Site

    SciTech Connect

    J.R. Giles; T.L. McLing; M.V. Carpenter; C.J. Smith; W. Brandon

    2012-12-01

    The Idaho National Laboratory (INL) recently provided technical support for ongoing environmental remediation activities at the Shepley’s Hill remediation site near Devens, MA (Figure 1). The technical support was requested as follow-on work to an initial screening level radiation survey conducted in 2008. The purpose of the original study was to assess the efficacy of the INL-developed Backpack Sodium Iodide System (BaSIS) for detecting elevated areas of natural radioactivity due to the decay of radon-222 gases emanating from the underlying fracture sets. Although the results from the initial study were mixed, the BaSIS radiation surveys did confirm that exposed bedrock outcrops have higher natural radioactivity than the surficial soils, thus a high potential for detecting elevated levels of radon and/or radon daughter products. (INL 2009) The short count times associated with the BaSIS measurements limited the ability of the system to respond to elevated levels of radioactivity from a subsurface source, in this instance radon gas emanating from fracture sets. Thus, it was postulated that a different methodology be employed to directly detect the radon in the soil gases. The CR-39 particle track detectors were investigated through an extensive literature and technology search. The relatively long deployment or “detection” time of several days, as well as the sensitivity of the measurement and robustness of the detectors made the CR-39 technology promising for deployment at the Shepley’s Hill site.

  8. Assimilation of Passive and Active Microwave Soil Moisture Retrievals

    NASA Technical Reports Server (NTRS)

    Draper, C. S.; Reichle, R. H.; DeLannoy, G. J. M.; Liu, Q.

    2012-01-01

    Root-zone soil moisture is an important control over the partition of land surface energy and moisture, and the assimilation of remotely sensed near-surface soil moisture has been shown to improve model profile soil moisture [1]. To date, efforts to assimilate remotely sensed near-surface soil moisture at large scales have focused on soil moisture derived from the passive microwave Advanced Microwave Scanning Radiometer (AMSR-E) and the active Advanced Scatterometer (ASCAT; together with its predecessor on the European Remote Sensing satellites (ERS. The assimilation of passive and active microwave soil moisture observations has not yet been directly compared, and so this study compares the impact of assimilating ASCAT and AMSR-E soil moisture data, both separately and together. Since the soil moisture retrieval skill from active and passive microwave data is thought to differ according to surface characteristics [2], the impact of each assimilation on the model soil moisture skill is assessed according to land cover type, by comparison to in situ soil moisture observations.

  9. Fluxes of CO2, CH4 and N2O at two European beech forests: linking soil gas production profiles with soil and stem fluxes

    NASA Astrophysics Data System (ADS)

    Maier, Martin; Machacova, Katerina; Halaburt, Ellen; Haddad, Sally; Urban, Otmar; Lang, Friederike

    2016-04-01

    Soil and plant surfaces are known to exchange greenhouse gases with the atmosphere. Some gases like nitrous oxide (N2O) and methane (CH4) can be produced and re-consumed in different soil depths and soil compartments, so that elevated concentrations of CH4 or N2O in the soil do not necessarily mean a net efflux from the soil into the atmosphere. Soil aeration, and thus the oxygen status can underlay a large spatial variability within the soil on the plot and profile scale, but also within soil aggregates. Thus, conditions suitable for production and consumption of CH4 and N2O can vary on different scales in the soil. Plant surfaces can also emit or take up CH4 and N2O, and these fluxes can significantly contribute to the net ecosystem exchange. Since roots usually have large intercellular spaces or aerenchyma they may represent preferential transport ways for soil gases, linking possibly elevated soil gas concentrations in the subsoil in a "shortcut" to the atmosphere. We tested the hypothesis that the spatial variability of the soil-atmosphere fluxes of CO2, CH4 and N2O is caused by the heterogeneity in soil properties. Therefore, we measured soil-atmosphere gas fluxes, soil gas concentrations and soil diffusivity profiles and did a small scale field assessment of soil profiles on the measurments plots. We further tried to link vertical profiles of soil gas concentrations and diffusivity to derive the production and consumption profiles, and to link these profiles to the stem-atmosphere flux rates of individual trees. Measurements were conducted in two mountain beech forests with different geographical and climatic conditions (White Carpathians, Czech Republic; Black Forest, Germany). Gas fluxes at stem and soil levels were measured simultaneously using static chamber systems and chromatographic and continuous laser analyses. Monitoring simultaneously vertical soil gas profiles allowed to assess the within-soil gas fluxes, and thus to localize the production and

  10. Investigation of shallow gas hydrate occurrence and gas seep activity on the Sakhalin continental slope, Russia

    NASA Astrophysics Data System (ADS)

    Jin, Young Keun; Baranov, Boris; Obzhirov, Anatoly; Salomatin, Alexander; Derkachev, Alexander; Hachikubo, Akihiro; Minami, Hrotsugu; Kuk Hong, Jong

    2016-04-01

    The Sakhalin continental slope has been a well-known gas hydrate area since the first finding of gas hydrate in 1980's. This area belongs to the southernmost glacial sea in the northern hemisphere where most of the area sea is covered by sea ice the winter season. Very high organic carbon content in the sediment, cold sea environment, and active tectonic regime in the Sakhalin slope provide a very favorable condition for occurring shallow gas hydrate accumulation and gas emission phenomena. Research expeditions under the framework of a Korean-Russian-Japanese long-term international collaboration projects (CHAOS, SSGH-I, SSGH-II projects) have been conducted to investigate gas hydrate occurrence and gas seepage activities on the Sakhalin continental slope, Russia from 2003 to 2015. During the expeditions, near-surface gas hydrate samples at more than 30 sites have been retrieved and hundreds of active gas seepage structures on the seafloor were newly registered by multidisciplinary surveys. The gas hydrates occurrence at the various water depths from about 300 m to 1000 m in the study area were accompanied by active gas seepage-related phenomena in the sub-bottom, on the seafloor, and in the water column: well-defined upward gas migration structures (gas chimney) imaged by high-resolution seismic, hydroacoustic anomalies of gas emissions (gas flares) detected by echosounders, seafloor high backscatter intensities (seepage structures) imaged by side-scan sonar and bathymetric structures (pockmarks and mounds) mapped by single/multi-beam surveys, and very shallow SMTZ (sulphate-methane transition zone) depths, strong microbial activities and high methane concentrations measured in sediment/seawater samples. The highlights of the expeditions are shallow gas hydrate occurrences around 300 m in the water depth which is nearly closed to the upper boundary of gas hydrate stability zone in the area and a 2,000 m-high gas flare emitted from the deep seafloor.

  11. Soil surface disturbances in cold deserts: Effects on nitrogenase activity in cyanobacterial-lichen soil crusts

    USGS Publications Warehouse

    Belnap, Jayne

    1996-01-01

    CyanobacteriaMichen soil crusts can be a dominant source of nitrogen for cold-desert ecosystems. Effects of surface disturbance from footprints, bike and vehicle tracks on the nitrogenase activity in these crusts was investigated. Surface disturbances reduced nitrogenase activity by 30-100%. Crusts dominated by the cyanobacterium Microcoleus vaginatus on sandy soils were the most susceptible to disruption; crusts on gypsiferous soils were the least susceptible. Crusts where the soil lichen Collema tenax was present showed less immediate effects; however, nitrogenase activity still declined over time. Levels of nitrogenase activity reduction were affected by the degree of soil disruption and whether sites were dominated by cyanobacteria with or without heterocysts. Consequently, anthropogenic surface disturbances may have serious implications for nitrogen budgets in these ecosystems.

  12. NO gas loss from biologically crusted soils in Canyonlands National Park, Utah

    USGS Publications Warehouse

    Barger, N.N.; Belnap, J.; Ojima, D.S.; Mosier, A.

    2005-01-01

    In this study, we examined N gas loss as nitric oxide (NO) from N-fixing biologically crusted soils in Canyonlands National Park, Utah. We hypothesized that NO gas loss would increase with increasing N fixation potential of the biologically crusted soil. NO fluxes were measured from biologically crusted soils with three levels of N fixation potential (Scytonema-Nostoc-Collema spp. (dark)>Scytonema-Nostoc-Microcoleus spp. (medium)>Microcoleus spp. (light)) from soil cores and field chambers. In both cores and field chambers there was a significant effect of crust type on NO fluxes, but this was highly dependent on season. NO fluxes from field chambers increased with increasing N fixation potential of the biologically crusted soils (dark>medium>light) in the summer months, with no differences in the spring and autumn. Soil chlorophyllasis Type a content (an index of N fixation potential), percent N, and temperature explained 40% of the variability in NO fluxes from our field sites. Estimates of annual NO loss from dark and light crusts was 0.04-0.16 and 0.02-0.11-N/ha/year. Overall, NO gas loss accounts for approximately 3-7% of the N inputs via N fixation in dark and light biologically crusted soils. Land use practices have drastically altered biological soil crusts communities over the past century. Livestock grazing and intensive recreational use of public lands has resulted in a large scale conversion of dark cyanolichen crusts to light cyanobacterial crusts. As a result, changes in biologically crusted soils in arid and semi-arid regions of the western US may subsequently impact regional NO loss. ?? Springer 2005.

  13. Risk assessment of gas oil and kerosene contamination on some properties of silty clay soil.

    PubMed

    Fallah, M; Shabanpor, M; Zakerinia, M; Ebrahimi, S

    2015-07-01

    Soil and ground water resource pollution by petroleum compounds and chemical solvents has multiple negative environmental impacts. The aim of this research was to investigate the impacts of kerosene and gas oil pollutants on some physical and chemical properties, breakthrough curve (BTC), and water retention curve (SWRC) of silty clay soil during a 3-month period. Therefore, some water-saturated soils were artificially contaminated in the pulse condition inside some glassy cylinders by applying half and one pore volume of these pollutants, and then parametric investigations of the SWRC were performed using RETC software for Van Genukhten and Brooks-Corey equations in the various suctions and the soil properties were determined before and after pollution during 3 months. The results showed that gas oil and kerosene had a slight effect on soil pH and caused the cumulative enhancement in the soil respiration, increase in the bulk density and organic matter, and reduction in the soil porosity and electrical and saturated hydraulic conductivity. Furthermore, gas oil retention was significantly more than kerosene (almost 40%) in the soil. The survey of SWRC indicated that the contaminated soil samples had a little higher amount of moisture retention (just under 15% in most cases) compared to the unpolluted ones during this 3-month period. The parametric analysis of SWRC demonstrated an increase in the saturated water content, Θ s, from nearly 49% in the control sample to just under 53% in the polluted ones. Contaminants not only decreased the residual water content, Θ r, but also reduced the SWRC gradient, n, and amount of α parameter. The evaluation of both equations revealed more accurate prediction of SWRC's parameters by Van Genukhten compared to those of Brooks and Corey.

  14. Forest and grassland cover types reduce net greenhouse gas emissions from agricultural soils.

    PubMed

    Baah-Acheamfour, Mark; Carlyle, Cameron N; Lim, Sang-Sun; Bork, Edward W; Chang, Scott X

    2016-11-15

    Western Canada's prairie region is extensively cultivated for agricultural production, which is a large source of greenhouse gas emissions. Agroforestry systems are common land uses across Canada, which integrate trees into the agricultural landscape and could play a substantial role in sequestering carbon and mitigating increases in atmospheric GHG concentrations. We measured soil CO2, CH4 and N2O fluxes and the global warming potential of microbe-mediated net greenhouse gas emissions (GWPm) in forest and herbland (areas without trees) soils of three agroforestry systems (hedgerow, shelterbelt and silvopasture) over two growing seasons (May through September in 2013 and 2014). We measured greenhouse gas fluxes and environmental conditions at 36 agroforestry sites (12 sites for each system) located along a south-north oriented soil/climate gradient of increasing moisture availability in central Alberta, Canada. The temperature sensitivity of soil CO2 emissions was greater in herbland (4.4) than in forest (3.1), but was not different among agroforestry systems. Over the two seasons, forest soils had 3.4% greater CO2 emission, 36% higher CH4 uptake, and 66% lower N2O emission than adjacent herbland soils. Combining the CO2 equivalents of soil CH4 and N2O fluxes with the CO2 emitted via heterotrophic (microbial) respiration, forest soils had a smaller GWPm than herbland soils (68 and 89kgCO2ha(-1), respectively). While emissions of total CO2 were silvopasture>hedgerow>shelterbelt, soils under silvopasture had 5% lower heterotrophic respiration, 15% greater CH4 uptake, and 44% lower N2O emission as compared with the other two agroforestry systems. Overall, the GWPm of greenhouse gas emissions was greater in hedgerow (88) and shelterbelt (85) than in the silvopasture system (76kgCO2ha(-1)). High GWPm in the hedgerow and shelterbelt systems reflects the greater contribution from the monoculture annual crops within these systems. Opportunities exist for reducing soil

  15. High temporal frequency measurements of greenhouse gas emissions from soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are the most important anthropogenic greenhouse gases (GHGs). Variation in soil moisture can be very dynamic, and it is one of the dominant factors controlling the net exchange of these three GHGs. Although technologies for high-frequency,...

  16. Effects of Carbon in Flooded Paddy Soils: Implications for Microbial Activity and Arsenic Mobilization

    NASA Astrophysics Data System (ADS)

    Avancha, S.; Boye, K.

    2014-12-01

    In the Mekong delta in Cambodia, naturally occurring arsenic (originating from erosion in the Himalaya Mountains) in paddy soils is mobilized during the seasonal flooding. As a consequence, rice grown on the flooded soils may take up arsenic and expose people eating the rice to this carcinogenic substance. Microbial activity will enhance or decrease the mobilization of arsenic depending on their metabolic pathways. Among the microbes naturally residing in the soil are denitrifying bacteria, sulfate reducers, metal reducers (Fe, Mn), arsenic reducers, methanogens, and fermenters, whose activity varies based on the presence of oxygen. The purpose of the experiment was to assess how different amendments affect the microbial activity and the arsenic mobilization during the transition from aerobic to anaerobic metabolism after flooding of naturally contaminated Cambodian soil. In a batch experiment, we investigated how the relative metabolic rate of naturally occurring microbes could vary with different types of organic carbon. The experiment was designed to measure the effects of various sources of carbon (dried rice straw, charred rice straw, manure, and glucose) on the microbial activity and arsenic release in an arsenic-contaminated paddy soil from Cambodia under flooded conditions. All amendments were added based on the carbon content in order to add 0.036 g of carbon per vial. The soil was flooded with a 10mM TRIS buffer solution at pH 7.04 in airtight 25mL serum vials and kept at 25 °C. We prepared 14 replicates per treatment to sample both gas and solution. On each sampling point, the solution replicates were sampled destructively. The gas replicates continued on and were sampled for both gas and solution on the final day of the experiment. We measured pH, total arsenic, methane, carbon dioxide, and nitrous oxide at 8 hours, 1.5 days, 3.33 days, and 6.33 days from the start of the experiment.

  17. Environmental factors influencing trace house gas production in permafrost-affected soils

    NASA Astrophysics Data System (ADS)

    Walz, Josefine; Knoblauch, Christian; Böhme, Luisa; Pfeiffer, Eva-Maria

    2016-04-01

    The permafrost-carbon feedback has been identified as a major feedback mechanism to climate change. Soil organic matter (SOM) decomposition in the active layer and thawing permafrost is an important source of atmospheric carbon dioxide (CO2) and methane (CH4). Decomposability and potential CO2 and CH4 production are connected to the quality of SOM. SOM quality varies with vegetation composition, soil type, and soil depth. The regulating factors affecting SOM decomposition in permafrost landscapes are not well understood. Here, we incubated permafrost-affected soils from a polygonal tundra landscape in the Lena Delta, Northeast Siberia, to examine the influence of soil depth, oxygen availability, incubation temperature, and fresh organic matter addition on trace gas production. CO2 production was always highest in topsoil (0 - 10 cm). Subsoil (10 - 50 cm) and permafrost (50 - 90 cm) carbon did not differ significantly in their decomposability. Under anaerobic conditions, less SOM was decomposed than under aerobic conditions. However, in the absence of oxygen, CH4 can also be formed, which has a substantially higher warming potential than CO2. But, within the four-month incubation period (approximate period of thaw), methanogenesis played only a minor role with CH4 contributing 1-30% to the total anaerobic carbon release. Temperature and fresh organic matter addition had a positive effect on SOM decomposition. Across a temperature gradient (1, 4, 8°C) aerobic decomposition in topsoil was less sensitive to temperature than in subsoil or permafrost. The addition of labile plant organic matter (13C-labelled Carex aquatilis, a dominant species in the region) significantly increased overall CO2 production across different depths and temperatures. Partitioning the total amount of CO2 in samples amended with Carex material into SOM-derived CO2 and Carex-derived CO2, however, revealed that most of the additional CO2 could be assigned to the organic carbon from the amendment

  18. Assessment of soil-gas and soil contamination at the Patterson Anti-Tank Range, Fort Gordon, Georgia, 2009-2010

    USGS Publications Warehouse

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

    2011-01-01

    Soil gas and soil were assessed for contaminants at the Patterson Anti-Tank Range at Fort Gordon, Georgia, from October 2009 to September 2010. The assessment included identifying and delineating organic contaminants present in soil-gas samplers from the area estimated to be the Patterson Anti-Tank Range and in the hyporheic zone and floodplain of Brier Creek. This assessment was conducted to provide environmental contamination data to Fort Gordon personnel pursuant to requirements for the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Soil-gas samplers in the hyporheic zone and floodplain of Brier Creek contained total petroleum hydrocarbons, benzene, octane, and pentadecane concentrations above method detection levels. All soil-gas samplers within the boundary of the Patterson Anti-Tank Range contained total petroleum hydrocarbons above the method detection level. The highest total petroleum hydrocarbon mass detected was 147.09 micrograms in a soil-gas sampler located near the middle of the site and near the remnants of a manmade earthen mound and trench. The highest toluene mass detected was 1.04 micrograms and was located in the center of the Patterson Anti-Tank Range and coincides with a manmade earthen mound. Some soil-gas samplers installed detected undecane masses greater than the method detection level of 0.04 microgram, with the highest detection of soil-gas undecane mass of 58.64 micrograms collected along the southern boundary of the site. Some soil-gas samplers were installed in areas of high-contaminant mass to assess for explosives and chemical agents. Explosives or chemical agents were not detected above their respective method detection levels for all soil-gas samplers installed.

  19. Climate-smart soils.

    PubMed

    Paustian, Keith; Lehmann, Johannes; Ogle, Stephen; Reay, David; Robertson, G Philip; Smith, Pete

    2016-04-07

    Soils are integral to the function of all terrestrial ecosystems and to food and fibre production. An overlooked aspect of soils is their potential to mitigate greenhouse gas emissions. Although proven practices exist, the implementation of soil-based greenhouse gas mitigation activities are at an early stage and accurately quantifying emissions and reductions remains a substantial challenge. Emerging research and information technology developments provide the potential for a broader inclusion of soils in greenhouse gas policies. Here we highlight 'state of the art' soil greenhouse gas research, summarize mitigation practices and potentials, identify gaps in data and understanding and suggest ways to close such gaps through new research, technology and collaboration.

  20. Microbial Enzyme Activity and Carbon Cycling in Grassland Soil Fractions

    NASA Astrophysics Data System (ADS)

    Allison, S. D.; Jastrow, J. D.

    2004-12-01

    Extracellular enzymes are necessary to degrade complex organic compounds present in soils. Using physical fractionation procedures, we tested whether old soil carbon is spatially isolated from degradative enzymes across a prairie restoration chronosequence in Illinois, USA. We found that carbon-degrading enzymes were abundant in all soil fractions, including macroaggregates, microaggregates, and the clay fraction, which contains carbon with a mean residence time of ~200 years. The activities of two cellulose-degrading enzymes and a chitin-degrading enzyme were 2-10 times greater in organic matter fractions than in bulk soil, consistent with the rapid turnover of these fractions. Polyphenol oxidase activity was 3 times greater in the clay fraction than in the bulk soil, despite very slow carbon turnover in this fraction. Changes in enzyme activity across the restoration chronosequence were small once adjusted for increases in soil carbon concentration, although polyphenol oxidase activity per unit carbon declined by 50% in native prairie versus cultivated soil. These results are consistent with a `two-pool' model of enzyme and carbon turnover in grassland soils. In light organic matter fractions, enzyme production and carbon turnover both occur rapidly. However, in mineral-dominated fractions, both enzymes and their carbon substrates are immobilized on mineral surfaces, leading to slow turnover. Soil carbon accumulation in the clay fraction and across the prairie restoration chronosequence probably reflects increasing physical isolation of enzymes and substrates on the molecular scale, rather than the micron to millimeter scale.

  1. Soil organic components distribution in a podzol and the possible relations with the biological soil activities

    NASA Astrophysics Data System (ADS)

    Alvarez-Romero, Marta; Papa, Stefania; Verstraeten, Arne; Curcio, Elena; Cools, Nathalie; Lozano-Garcia, Beatriz; Parras-Alcántara, Luis; Coppola, Elio

    2016-04-01

    This research reports the preliminary results of a study based on the SOC (Soil Organic Carbon) fractionation in a pine forest soil (Pinus nigra). Hyperskeletic Albic Podzol soil (P113005, World Reference Base, 2014), described by the following sequence O-Ah-E-Bh-Bs-Cg, was investigated at Zoniën, Belgium. Total (TOC) and extractable (TEC) soil contents were determined by Italian official method of soil analysis. Different soil C fractions were also determined: Humic Acid Carbon (HAC) and Fulvic Acid Carbon (FAC). Not Humic Carbon (NHC) and Humin Carbon (Huc) fractions were obtained by difference. Along the mineral soil profile, therefore, were also tested some enzymatic activities, such as cellulase, xylanase, laccase and peroxidase, involved in the degradation of the main organic substance components, and dehydrogenase activity, like soil microbial biomass index. The results shows a differential TEC fractions distribution in the soil profile along three fronts of progress: (i) An E leaching horizon of TEC; Bh horizon (humic) of humic acids preferential accumulation, morphologically and analytically recognizable, in which humic are more insoluble that fulvic acids, and predominate over the latter; (ii) horizon Bs (spodic) in which fulvic acids are more soluble that humic acid, and predominate in their turn. All enzyme activities appear to be highest in the most superficial part of the mineral profile and decrease towards the deeper layers with different patterns. It is known that the enzymes production in a soil profile reflects the organic substrates availability, which in turn influences the density and the composition of the microbial population. The deeper soil horizons contain microbial communities adapted and specialized to their environment and, therefore, different from those present on the surface The results suggest that the fractionation technique of TEC is appropriate to interpret the podsolisation phenomenon that is the preferential distribution of

  2. Effects of agricultural tillage practise on green house gas balance of an arable soil in a long term field experiment

    NASA Astrophysics Data System (ADS)

    Munch, Jean Charles; Schilling, Rolf; Ruth, Bernhard; Fuss, Roland

    2010-05-01

    Soils are an important part of the global carbon cycle. A large proportion of global carbon dioxide (CO2) emissions is released from soils, though carbon sequestration occurs. Nitrous oxide (N2O) emissions of soils are also believed to contribute significantly to the green house effect as well as the stratospheric ozone depletion. An important source of N2O emissions is denitrification of nitrate from nitrogen fertilized soils. Although it is desirable to minimize these emissions while maintaining high crop yields it is still poorly understood how green house gas emissions may be steered by agricultural management practise, i.e. tillage and fertilization systems . In an ongoing long term field experiment at the research farm Scheyern, Bavaria, a arable field with one homogenous soil formation was transformed into plots in a randomized design 14 years ago. Since then, they are managed using conventional tillage (CT) and no tillage (NT) as well as low and high fertilization. A conventional crop rotation is maintained on the field. Starting 2007, CO2 and N2O emissions were monitored continuously for 2.5 years. Furthermore water content, temperature and redox potential were measured in-situ as they are major factors on microbial activity and denitrification. Soil was sampled from the Ap horizons of the plots about twice a month and extracts from these soil samples were analyzed for dissolved organic carbon (DOC), ammonium, nitrate/nitrite, and dissolved organic nitrogen (DON). According to the results soil density and hydrology are clearly affected by tillage practise. DOC is more affected by tillage while concentration of nitrogen species is controlled mainly by fertilization. There are distinct differences in redox potential between CT and NT plots with CT plots having more anaerobic periods. CO2 and N2O emissions exhibit a clear seasonal pattern and are affected by both tillage system and fertilization

  3. Numerical study on the deformation of soil stratum and vertical wells with gas hydrate dissociation

    NASA Astrophysics Data System (ADS)

    Chen, Xudong; Zhang, Xuhui; Lu, Xiaobing; Wei, Wei; Shi, Yaohong

    2016-10-01

    Gas hydrate (GH) dissociates owing to thermal injection or pressure reduction from the well in gas/oil or GH exploitation. GH dissociation leads to, for example, decreases in soil strength, engineering failures such as wellbore instabilities, and marine landslides. The FLAC3D software was used to analyze the deformation of the soil stratum and vertical wells with GH dissociation. The effects of Young's modulus, internal friction angle, cohesion of the GH layer after dissociation, and the thickness of the GH layer on the deformation of soils were studied. It is shown that the maximum displacement in the whole soil stratum occurs at the interface between the GH layer and the overlayer. The deformation of the soil stratum and wells increases with decreases in the modulus, internal friction angle, and cohesion after GH dissociation. The increase in thickness of the GH layer enlarges the deformation of the soil stratum and wells with GH dissociation. The hydrostatic pressure increases the settlement of the soil stratum, while constraining horizontal displacement. The interaction between two wells becomes significant when the affected zone around each well exceeds half the length of the GH dissociation zone.

  4. Stable isotopes of carbon dioxide in soil gas over massive sulfide mineralization at Crandon, Wisconsin

    USGS Publications Warehouse

    Alpers, C.N.; Dettman, D.L.; Lohmann, K.C.; Brabec, D.

    1990-01-01

    Stable isotope ratios of oxygen and carbon were determined for CO2 in soil gas in the vicinity of the massive sulfide deposit at Crandon, Wisconsin with the objective of determining the source of anomalously high CO2 concentrations detected previously by McCarthy et al. (1986). Values of ??13C in soil gas CO2 from depths between 0.5 and 1.0 m were found to range from -12.68??? to -20.03??? (PDB). Organic carbon from the uppermost meter of soil has ??13C between -24.1 and -25.8??? (PDB), indicating derivation from plant species with the C3 (Calvin) type of photosynthetic pathway. Microbial decomposition of the organic carbon and root respiration from C3 and C4 (Hatch-Slack) plants, together with atmospheric CO2 are the likely sources of carbon in soil gas CO2. Values of ??18O in soil-gas CO2 range from 32 to 38??? (SMOW). These ??18O values are intermediate between that calculated for CO2 gas in isotopic equilibrium with local groundwaters and that for atmospheric CO2. The ??18O data indicate that atmospheric CO2 has been incorporated by mixing or diffusion. Any CO2 generated by microbial oxidation of organic matter has equilibrated its oxygen isotopes with the local groundwaters. The isotopic composition of soil-gas CO2 taken from directly above the massive sulfide deposit was not distinguishable from that of background samples taken 1 to 2 km away. No enrichment of the ??13C value of soil-gas CO2 was observed, contrary to what would be expected if the anomalous CO2 were derived from the dissolution of Proterozoic marine limestone country rock or of Paleozoic limestone clasts in glacial till. Therefore, it is inferred that root respiration and decay of C3 plant material were responsible for most CO2 generation both in the vicinity of the massive sulfide and in the "background" area, on the occasion of our sampling. Interpretation of our data is complicated by the effects of rainfall, which significantly reduced the magnitude of the CO2 anomaly. Therefore, we cannot

  5. Arid soil microbial enzymatic activity profile as affected by geographical location and soil degradation status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluating soil health is critical for any successful remediation effort. Arid lands, with their minimal carbon and water contents, low nutritional status and restricted, seasonal microbial activity pose specific challenges to soil health restoration and by extension, restoration of ecosystem repr...

  6. Process modeling of controls on nitrogen trace gas emissions from soils worldwide

    NASA Astrophysics Data System (ADS)

    Potter, Christopher S.; Matson, Pamela A.; Vitousek, Peter M.; Davidson, Eric A.

    1996-01-01

    We report on an ecosystem modeling approach that integrates global satellite, climate, vegetation, and soil data sets to (1) examine conceptual controls on nitrogen trace gas (NO, N2O, and N2) emissions from soils and (2) identify weaknesses in our bases of knowledge and data for these fluxes. Nitrous and nitric oxide emissions from well-drained soils were estimated by using an expanded version of the Carnegie-Ames-Stanford (CASA) Biosphere model, a coupled ecosystem production and soil carbon-nitrogen model on a 1° global grid. We estimate monthly production of NO, N2O, and N2 based on predicted rates of gross N mineralization, together with an index of transient water-filled pore space in soils. Analyses of model performance along selected climate gradients support the hypothesis that low temperature restricts predicted N mineralization and trace gas emission rates in moist northern temperate and boreal forest ecosystems, whereas in tropical zones, seasonal patterns in N mineralization result in emission peaks for N2O that coincide with wetting and high soil moisture content. The model predicts the annual N2O:NO flux ratio at a mean value of 1.2 in wet tropical forests, decreasing to around 0.6 in the seasonally dry savannas. Global emission estimates at the soil surface are 6.1 Tg N and 9.7 Tg N yr-1 for N2O and NO, respectively. Tropical dry forests and savannas are identified by using this formulation as important source areas for nitrogen trace gas emissions. Because humans continue to alter these ecosystems extensively for agricultural uses, our results suggest that more study is needed in seasonally dry ecosystems of the tropics in order to understand the global impacts of land use change on soil sources for N2O and NO.

  7. Active faults on the eastern flank of Etna volcano (Italy) monitored through soil radon measurements

    NASA Astrophysics Data System (ADS)

    Neri, M.; Giammanco, S.; Ferrera, E.; Patanè, G.; Zanon, V.

    2012-04-01

    This study concerns measurements of radon and thoron emissions from soil carried out in 2004 on the unstable eastern flank of Mt. Etna, in a zone characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds for both parameters and producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. In particular, the highest anomalies were found at the intersection between WNW-ESE and NW-SE -running faults. The seismic activity occurring in and around the study area during 2004 was analyzed, producing maps of hypocentral depth and released seismic energy. These maps revealed a progressive deepening of hypocenters from NW to SE, with the exception of a narrow zone in the central part of the area, with a roughly WNW-ESE direction. Also, the highest values of seismic energy were released during events in the southern and northwestern sectors of the area. Both radon and thoron anomalies were located in areas affected by relatively deep (5-10 km depth) seismic activity, while less evident correlation was found between soil gas anomalies and the released seismic energy. This study confirms that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover or faults that are not clearly visible at the surface. The correlation between soil gas data and earthquake depth and intensity can give some hints on the source of gas and/or on fault dynamics. Lastly, an important spin-off of this study is the recognition of some areas where radon activity was so high (>50000 Bq/m3) that it may represent a potential hazard to the local population. In fact, radon is the leading cause of lung cancer after cigarette smoke for long exposures and, due to its molecular weight, it accumulates in underground rooms or in low ground, particularly where air circulation is low or absent

  8. Soil Incubation Study to Assess the Impacts of Manure Application and Climate Change on Greenhouse Gas Emissions from Agricultural Soil

    NASA Astrophysics Data System (ADS)

    Schiavone, K.; Barbieri, L.; Adair, C.

    2015-12-01

    Agricultural fields in Vermont's Lake Champlain Basin have problems with the loss of nutrients due to runoff which creates eutrophic conditions in the lakes, ponds and rivers. In efforts to retain nitrogen and other nutrients in the soil farmers have started to inject manure rather than spraying it. Our understanding of the effects this might have on the volatilization of nitrogen into nitrous oxide is limited. Already, agriculture produces 69% of the total nitrous oxide emissions in the US. Understanding that climate change will affect the future of agriculture in Vermont, we set up a soil core incubation test to monitor the emissions of CO₂ and N₂O using a Photoacoustic Gas Sensor (PAS). Four 10 cm soil cores were taken from nine different fertilizer management plots in a No Till corn field; Three Injected plots, three Broadcast plots, and three Plow plots. Frozen soil cores were extracted in early April, and remained frozen before beginning the incubation experiment to most closely emulate three potential spring environmental conditions. The headspace was monitored over one week to get emission rates. This study shows that environmental and fertilizer treatments together do not have a direct correlation to the amount of CO₂ and N₂O emissions from agricultural soil. However, production of CO₂ was 26% more in warmer environmental conditions than in variable(freeze/thaw) environmental conditions. The injected fertilizer produced the most emissions, both CO₂ and N₂O. The total N₂O emissions from Injected soil cores were 2.2x more than from traditional broadcast manure cores. We believe this is likely due to the addition of rich organic matter under anaerobic soil conditions. Although, injected fertilizer is a better application method for reducing nutrient runoff, the global warming potential of N₂O is 298 times that of CO₂. With climate change imminent, assessing the harmful effects and benefits of injected fertilizer is a crucial next step in

  9. NASA's Soil Moisture Active Passive (SMAP) Observatory

    NASA Technical Reports Server (NTRS)

    Kellogg, Kent; Thurman, Sam; Edelstein, Wendy; Spencer, Michael; Chen, Gun-Shing; Underwood, Mark; Njoku, Eni; Goodman, Shawn; Jai, Benhan

    2013-01-01

    The SMAP mission will produce high-resolution and accurate global maps of soil moisture and its freeze/thaw state using data from a non-imaging synthetic aperture radar and a radiometer, both operating at L-band.

  10. Seasonal greenhouse gas and soil nutrient cycling in semi-arid native and non-native perennial grass pastures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Photosynthetic metabolism in warm- and cool-season grass species affects greenhouse gas (GHG) emissions from soils. The major soil GHGs are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Monitoring seasonal variability of GHG and soil carbon (C) and nitrogen (N) from Central Oklahoma...

  11. Long-term tillage and drainage influences on greenhouse gas fluxes from a poorly-drained soil of central Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Intensive tillage practices and poorly-drained soils of Midwestern USA are the prime reasons for greenhouse gas (GHG) fluxes from agriculture. The naturally poorly-drained soils prevalent in this region require subsurface drainage for improved aeration and improved crop productivity. Soil surface GH...

  12. Greenhouse gas production in mixtures of soil with composted and noncomposted biochars is governed by char-associated organic compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar application to soil has the potential to increase soil productivity while reducing anthropogenic net greenhouse gas (GHG) emissions to the atmosphere by sequestering carbon that has been assimilated by plants in a stabilized form. Techniques for conditioning this material as a soil amendment...

  13. Studying the Activities of Microorganisms in Soil Using Slides.

    ERIC Educational Resources Information Center

    Cullimore, D. Roy; Pipe, Annette E.

    1980-01-01

    Two implanted slide techniques are described by which activity of proteolylic bacteria and the growth of algae in the soil can be readily studied by school students using simple apparatus and methods. Variations are suggested for studying the effects of agricultural practices and environmental conditions on the soil bacteria and algae. (Author/DS)

  14. Measurements of microbial community activities in individual soil macroaggregates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The functional potential of single soil aggregates may provide insights into the localized distribution of microbial activities better than traditional assays conducted on bulk quantities of soil. Thus, we scaled down enzyme assays for ß-glucosidase, N-acetyl-ß-D-glucosaminidase, lipase, and leucine...

  15. Activation energies and temperature effects from electrical spectra of soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Apparent permittivity often has soil-specific temperature responses as well as soil water responses. These variations affect dielectric sensors, often requiring site-specific calibrations. Variations of permittivity as a function of frequency and temperature can be used to calculate activation energ...

  16. The Soil Moisture Active/Passive Mission (SMAP)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Soil Moisture Active/Passive (SMAP) mission will deliver global views of soil moisture content and its freeze/thaw state that are critical terrestrial water cycle state variables. Polarized measurements obtained with a shared antenna L-band radar and radiometer system will allow accurate estima...

  17. Seasonal variability of soil-gas radon concentration in central California

    USGS Publications Warehouse

    King, C.-Y.; Minissale, A.

    1994-01-01

    Radon concentrations in soil gas were measured by the track-etch method in 60 shallow holes, each 70 cm deep and supported by a capped plastic tube, along several major faults in central California during 1975-1985. This set of data was analyzed to investigate the seasonal variability of soil-gas radon concentration in an area which has various geological conditions but similar climate. The results show several different patterns of seasonal variations, but all of which can be largely attributed to the water-saturation and moisture-retention characteristics of the shallow part of the soil. During the rainy winter and spring seasons, radon tended to be confined underground by the water-saturated surface soil which had much reduced gas permeability, while during the sunny summer and autumn seasons, it exhaled more readily as the soil became drier and more permeable. At several sites located on creeping faults, the radon-variation patterns changed with time, possibly because of disturbance of site condition by fault movement. ?? 1994.

  18. Microbial activity in Alaskan taiga soils contaminated by crude oil in 1976

    SciTech Connect

    Monroe, E.M.; Lindstrom, J.E.; Brown, E.J.; Raddock, J.F. |

    1995-12-31

    Biodegradation, often measured via microbial activity, includes destruction of environmental pollutants by living microorganisms and is dependent upon many physical and chemical factors. Effects of mineral nutrients and organic matter on biodegradation of Prudhoe Bay crude oil were investigated at a nineteen-year-old oil spill site in Alaskan taiga. Microcosms of two different soil types from the spill site; one undeveloped soil with forest litter and detritus (O horizon) and one more developed with lower organic content (A horizon), were treated with various nitrogen and phosphorus amendments, and incubated for up to six weeks. Each microcosm was sampled periodically and assayed for hydrocarbon mineralization potential using radiorespirometry, for total carbon dioxide respired using gas chromatography, and for numbers of hydrocarbon-degrading bacteria and heterotrophic bacteria using most probable number counting techniques. Organic matter in the O horizon soil along with combinations of mineral nutrients were found to stimulate microbial activity. No combination of mineral nutrient additions to the A horizon soil stimulated any of the parameters above those measured in control microcosms. The results of this study indicate that adding mineral nutrients and tilling the O horizon into the A horizon of subarctic soils contaminated with crude oil, would stimulate microbial activity, and therefore the biodegradation potential, ultimately increasing the rate of destruction of crude oil in these soils.

  19. Soil radon measurements as a potential tracer of tectonic and volcanic activity.

    PubMed

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-04-15

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009-2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

  20. Soil radon measurements as a potential tracer of tectonic and volcanic activity

    PubMed Central

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-01-01

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009–2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes. PMID:27079264

  1. Soil radon measurements as a potential tracer of tectonic and volcanic activity

    NASA Astrophysics Data System (ADS)

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-04-01

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009–2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

  2. Quantifying biases in non-steady state chamber measurements of soil-atmosphere gas exchange

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Limitations of non-steady state (NSS) chamber methods for determining soil-to-atmosphere trace gas exchange rates have been recognized for several decades. Of these limitations, the so-called “chamber effect” is one of the most challenging to overcome. The chamber effect can be defined as the inhere...

  3. Groundwater pollution potential and greenhouse gas emission from soils amended with different swine biochars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although there exist numerous research studies in the literature on greenhouse gas emission and groundwater pollution potentials of soils amended with plant-based biochar made from traditional dry pyrolysis (hereafter referred as pyrochar), a very few such studies exist for hydrochar made from hydro...

  4. Soil Nitrous Oxide Emissions with Crop Production for Biofuel: Implications for Greenhouse Gas Mitigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The growing biofuel commodity market for corn ethanol has the potential to reduce direct greenhouse gas (GHG) emissions associated with fossil fuel combustion in the US. However, projected increases in cropland to accommodate this energy-based commodity will also impact emissions of GHGs from soils...

  5. EVALUATION OF VAPOR EQUILIBRATION AND IMPACT OF PURGE VOLUME ON SOIL-GAS SAMPLING RESULTS

    EPA Science Inventory

    Sequential sampling was utilized at the Raymark Superfund site to evaluate attainment of vapor equilibration and the impact of purge volume on soil-gas sample results. A simple mass-balance equation indicates that removal of three to five internal volumes of a sample system shou...

  6. CAUSES OF POOR SEALANT PERFORMANCE IN SOIL-GAS- RESISTANT FOUNDATIONS

    EPA Science Inventory

    The paper discusses causes of poor sealant performance in soil-gas-resistant foundations. ealants for radon-resistant foundation construction must seal the gap between concrete sections. odern sealants have such low permeability that seal performance depends only on the permeabil...

  7. MACRO- MICRO-PURGE SOIL GAS SAMPLING METHODS FOR THE COLLECTION OF CONTAMINANT VAPORS

    EPA Science Inventory

    Purging influence on soil gas concentrations for volatile organic compounds (VOCs), as affected by sampling tube inner diameter and sampling depth (i.e., dead-space purge volume), was evaluated at different field sites. A macro-purge sampling system consisted of a standard hollo...

  8. Calculating the detection limits of chamber-based soil greenhouse gas flux measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Renewed interest in quantifying greenhouse gas emissions from soil has lead to an increase in the application of chamber-based flux measurement techniques. Despite the apparent conceptual simplicity of chamber-based methods, nuances in chamber design, deployment, and data analyses can have marked ef...

  9. Corn stover removal impacts on soil greenhouse gas emissions in irrigated continuous corn systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Harvesting corn stover for livestock feed or for cellulosic biofuel production may impact the greenhouse gas (GHG) mitigation potential of high-yield irrigated corn. Soil emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) were measured over the 2011 growing season at two irri...

  10. Soil-gas and indoor radon distribution related to geology in Frederick County, Maryland

    SciTech Connect

    Szarzi, S.L.; Reimer, G.M.; Been, J.M.

    1992-12-31

    Soil-gas radon concentrations vary in response to geologic controls in Frederick County, Maryland, and the variation leads to different radon availabilities for potential indoor accumulations. Quartzites, which form from the core of ridges and mountains of the southern and western part of the county, have a mean soil-gas radon concentration of 26 kBq m{sup -3} (700 pCi L{sup -1}). Phyllites, found in the Piedmont province in the eastern part of the county, have a mean soil-gas radon concentration of 59 kBq m{sup -3} (1600 pCi L{sup -1}). Many indoor radon measurements for homes in the southeast portion of the county, made by means of charcoal canisters, exceeded 1850 Bq m{sup -3} (50 pCi L{sup -1}). Homes built in areas where the soil-gas radon concentrations were greater than 75 kBq m{sup -3} (2000 pCi L{sup -1}) may have indoor radon concentrations that exceed 150 Bq m{sup -3} (4 pCi L{sup -1}), the current action level recommended by the U.S. Environmental Protection Agency. Data obtained in studies like ours throughout the United States are essential to identify {open_quotes}hot spots{close_quotes} which may produce elevated indoor radon levels of significant risk.

  11. Measurement of greenhouse gas flux from agricultural soils using static chambers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the biogeochemical drivers of climate change and to the development and evaluation of GHG mitigation strategies based on modulation of landscape mana...

  12. Using Concentrations of Methane and Gasoline Hydrocarbons in Soil Gas to Predict Vapor Intrusion of Benzene

    EPA Science Inventory

    Risk management of petroleum vapor intrusion has been a daunting and challenging task for the Underground Storage Tank Program. Because chlorinated solvents do not degrade in soil gas, techniques that focus on their properties and behavior can produce useful estimates. However, t...

  13. CORRELATION OF FLORIDA SOIL-GAS PERMEABILITIES WITH GRAIN SIZE, MOISTURE, AND POROSITY

    EPA Science Inventory

    The report describes a new correlation or predicting gas permeabilities of undisturbed or recompacted soils from their average grain diameter (d), moisture saturation factor (m), and porosity (p). he correlation exhibits a geometric standard deviation (GSD) of only 1.27 between m...

  14. Application of colloidal gas aphron suspensions produced from Sapindus mukorossi for arsenic removal from contaminated soil.

    PubMed

    Mukhopadhyay, Soumyadeep; Mukherjee, Sumona; Hashim, Mohd Ali; Sen Gupta, Bhaskar

    2015-01-01

    Colloidal gas aphron dispersions (CGAs) can be described as a system of microbubbles suspended homogenously in a liquid matrix. This work examines the performance of CGAs in comparison to surfactant solutions for washing low levels of arsenic from an iron rich soil. Sodium Dodecyl Sulfate (SDS) and saponin, a biodegradable surfactant, obtained from Sapindus mukorossi or soapnut fruit were used for generating CGAs and solutions for soil washing. Column washing experiments were performed in down-flow and up flow modes at a soil pH of 5 and 6 using varying concentration of SDS and soapnut solutions as well as CGAs. Soapnut CGAs removed more than 70% arsenic while SDS CGAs removed up to 55% arsenic from the soil columns in the soil pH range of 5-6. CGAs and solutions showed comparable performances in all the cases. CGAs were more economical since it contains 35% of air by volume, thereby requiring less surfactant. Micellar solubilization and low pH of soapnut facilitated arsenic desorption from soil column. FT-IR analysis of effluent suggested that soapnut solution did not interact chemically with arsenic thereby facilitating the recovery of soapnut solution by precipitating the arsenic. Damage to soil was minimal arsenic confirmed by metal dissolution from soil surface and SEM micrograph.

  15. Microbial Activity in Organic Soils as Affected by Soil Depth and Crop †

    PubMed Central

    Tate, Robert L.

    1979-01-01

    The microbial activity of Pahokee muck, a lithic medisaprist, and the effect of various environmental factors, such as position in the profile and type of plant cover, were examined. Catabolic activity for [7-14C]salicylic acid, [1,4-14C]succinate, and [1,2-14C]acetate remained reasonably constant in surface (0 to 10 cm) soil samples from a fallow (bare) field from late in the wet season (May to September) through January. Late in January, the microbial activity toward all three compounds decreased approximately 50%. The microbial activity of the soil decreased with increasing depth of soil. Salicylate catabolism was the most sensitive to increasing moisture deep in the soil profile. At the end of the wet season, a 90% decrease in activity between the surface and the 60- to 70-cm depth occurred. Catabolism of acetate and succinate decreased approximately 75% in the same samples. Little effect of crop was observed. Variation in the microbial activity, as measured by the catabolism of labeled acetate, salicylate, or succinate, was not significant between a sugarcane (Saccharum officinarum L.) field and a fallow field. The activity with acetate was insignificantly different in a St. Augustine grass [Stenotaphrum secundatum (Walt) Kuntz] field, whereas the catabolism of the remaining substrates was elevated in the grass field. These results indicate that the total carbon evolved from the different levels of the soil profile by the microbial community oxidizing the soil organic matter decreased as the depth of the soil column increased. However, correction of the amount of carbon yielded at each level for the bulk density of that level reveals that the microbial contribution to the soil subsidence is approximately equivalent throughout the soil profile above the water table. PMID:16345393

  16. Soil greenhouse gas emissions and carbon budgeting in a short-hydroperiod floodplain wetland

    USGS Publications Warehouse

    Batson, Jackie; Noe, Gregory B.; Hupp, Cliff R.; Krauss, Ken W.; Rybicki, Nancy B.; Schenk, Edward R.

    2015-01-01

    Understanding the controls on floodplain carbon (C) cycling is important for assessing greenhouse gas emissions and the potential for C sequestration in river-floodplain ecosystems. We hypothesized that greater hydrologic connectivity would increase C inputs to floodplains that would not only stimulate soil C gas emissions but also sequester more C in soils. In an urban Piedmont river (151 km2 watershed) with a floodplain that is dry most of the year, we quantified soil CO2, CH4, and N2O net emissions along gradients of floodplain hydrologic connectivity, identified controls on soil aerobic and anaerobic respiration, and developed a floodplain soil C budget. Sites were chosen along a longitudinal river gradient and across lateral floodplain geomorphic units (levee, backswamp, and toe slope). CO2 emissions decreased downstream in backswamps and toe slopes and were high on the levees. CH4 and N2O fluxes were near zero; however, CH4emissions were highest in the backswamp. Annual CO2 emissions correlated negatively with soil water-filled pore space and positively with variables related to drier, coarser soil. Conversely, annual CH4 emissions had the opposite pattern of CO2. Spatial variation in aerobic and anaerobic respiration was thus controlled by oxygen availability but was not related to C inputs from sedimentation or vegetation. The annual mean soil CO2 emission rate was 1091 g C m−2 yr−1, the net sedimentation rate was 111 g C m−2 yr−1, and the vegetation production rate was 240 g C m−2 yr−1, with a soil C balance (loss) of −338 g C m−2 yr−1. This floodplain is losing C likely due to long-term drying from watershed urbanization.

  17. Soil greenhouse gas emissions and carbon budgeting in a short-hydroperiod floodplain wetland

    NASA Astrophysics Data System (ADS)

    Batson, Jackie; Noe, Gregory B.; Hupp, Cliff R.; Krauss, Ken W.; Rybicki, Nancy B.; Schenk, Edward R.

    2015-01-01

    the controls on floodplain carbon (C) cycling is important for assessing greenhouse gas emissions and the potential for C sequestration in river-floodplain ecosystems. We hypothesized that greater hydrologic connectivity would increase C inputs to floodplains that would not only stimulate soil C gas emissions but also sequester more C in soils. In an urban Piedmont river (151 km2 watershed) with a floodplain that is dry most of the year, we quantified soil CO2, CH4, and N2O net emissions along gradients of floodplain hydrologic connectivity, identified controls on soil aerobic and anaerobic respiration, and developed a floodplain soil C budget. Sites were chosen along a longitudinal river gradient and across lateral floodplain geomorphic units (levee, backswamp, and toe slope). CO2 emissions decreased downstream in backswamps and toe slopes and were high on the levees. CH4 and N2O fluxes were near zero; however, CH4 emissions were highest in the backswamp. Annual CO2 emissions correlated negatively with soil water-filled pore space and positively with variables related to drier, coarser soil. Conversely, annual CH4 emissions had the opposite pattern of CO2. Spatial variation in aerobic and anaerobic respiration was thus controlled by oxygen availability but was not related to C inputs from sedimentation or vegetation. The annual mean soil CO2 emission rate was 1091 g C m-2 yr-1, the net sedimentation rate was 111 g C m-2 yr-1, and the vegetation production rate was 240 g C m-2 yr-1, with a soil C balance (loss) of -338 g C m-2 yr-1. This floodplain is losing C likely due to long-term drying from watershed urbanization.

  18. Dynamics of soil organic carbon and microbial activity in treated wastewater irrigated agricultural soils along soil profiles

    NASA Astrophysics Data System (ADS)

    Jüschke, Elisabeth; Marschner, Bernd; Chen, Yona; Tarchitzky, Jorge

    2010-05-01

    Treated wastewater (TWW) is an important source for irrigation water in arid and semiarid regions and already serves as an important water source in Jordan, the Palestinian Territories and Israel. Reclaimed water still contains organic matter (OM) and various compounds that may effect microbial activity and soil quality (Feigin et al. 1991). Natural soil organic carbon (SOC) may be altered by interactions between these compounds and the soil microorganisms. This study evaluates the effects of TWW irrigation on the quality, dynamics and microbial transformations of natural SOC. Priming effects (PE) and SOC mineralization were determined to estimate the influence of TWW irrigation on SOC along soil profiles of agricultural soils in Israel and the Westbank. The used soil material derived from three different sampling sites allocated in Israel and The Palestinian Authority. Soil samples were taken always from TWW irrigated sites and control fields from 6 different depths (0-10, 10-20, 20-30, 30-50, 50-70, 70-100 cm). Soil carbon content and microbiological parameters (microbial biomass, microbial activities and enzyme activities) were investigated. In several sites, subsoils (50-160 cm) from TWW irrigated plots were depleted in soil organic matter with the largest differences occurring in sites with the longest TWW irrigation history. Laboratory incubation experiments with additions of 14C-labelled compounds to the soils showed that microbial activity in freshwater irrigated soils was much more stimulated by sugars or amino acids than in TWW irrigated soils. The lack of such "priming effects" (Hamer & Marschner 2005) in the TWW irrigated soils indicates that here the microorganisms are already operating at their optimal metabolic activity due to the continuous substrate inputs with soluble organic compounds from the TWW. The fact that PE are triggered continuously due to TWW irrigation may result in a decrease of SOC over long term irrigation. Already now this could be

  19. Soil biological activity at European scale - two calculation concepts

    NASA Astrophysics Data System (ADS)

    Krüger, Janine; Rühlmann, Jörg

    2014-05-01

    The CATCH-C project aims to identify and improve the farm-compatibility of Soil Management Practices including to promote productivity, climate change mitigation and soil quality. The focus of this work concentrates on turnover conditions for soil organic matter (SOM). SOM is fundamental for the maintenance of quality and functions of soils while SOM storage is attributed a great importance in terms of climate change mitigation. The turnover conditions depend on soil biological activity characterized by climate and soil properties. To assess the turnover conditions two model concepts are applied: (I) Biological active time (BAT) regression approach derived from CANDY model (Franko & Oelschlägel 1995) expresses the variation of air temperature, precipitation and soil texture as a timescale and an indicator of biological activity for soil organic matter (SOM) turnover. (II) Re_clim parameter within the Introductory Carbon Balance Model (Andrén & Kätterer 1997) states the soil temperature and soil water to estimate soil biological activity. The modelling includes two strategies to cover the European scale and conditions. BAT was calculated on a 20x20 km grid basis. The European data sets of precipitation and air temperature (time period 1901-2000, monthly resolution), (Mitchell et al. 2004) were used to derive long-term averages. As we focus on agricultural areas we included CORINE data (2006) to extract arable land. The resulting BATs under co-consideration of the main soil textures (clay, silt, sand and loam) were investigated per environmental zone (ENZs, Metzger et al. 2005) that represents similar conditions for precipitation, temperature and relief to identify BAT ranges and hence turnover conditions for each ENZ. Re_clim was quantified by climatic time series of more than 250 weather stations across Europe presented by Klein Tank et al. (2002). Daily temperature, precipitation and potential evapotranspiration (maximal thermal extent) were used to calculate

  20. Cratering Soil by Impinging Jets of Gas, with Application to Landing Rockets on Planetary Surfaces

    NASA Technical Reports Server (NTRS)

    Metzger, Philip T.; Vu, B. T.; Taylor, D. E.; Kromann, M. J.; Fuchs, M.; Yutko, B.; Dokos, A.; Immer, Christopher D.; Lane, J. E.; Dunkel, Michael B.; Donahue, Carly M.; Latta, R. C., III

    2007-01-01

    Several physical mechanisms are involved in excavating granular materials beneath a vertical jet of gas. These occur, for example, beneath the exhaust plume of a rocket landing on the soil of the Moon or Mars. A series of experiments and simulations have been performed to provide a detailed view of the complex gas/soil interactions. Measurements have also been taken from the Apollo lunar landing videos and from photographs of the resulting terrain, and these help to demonstrate how the interactions extrapolate into the lunar environment. It is important to understand these processes at a fundamental level to support the ongoing design of higher-fidelity numerical simulations and larger-scale experiments. These are needed to enable future lunar exploration wherein multiple hardware assets will be placed on the Moon within short distances of one another. The high-velocity spray of soil from landing spacecraft must be accurately predicted and controlled lest it erosively damage the surrounding hardware.

  1. Soil biological activity as affected by tillage intensity

    NASA Astrophysics Data System (ADS)

    Gajda, A.; Przewłoka, B.

    2012-02-01

    The effect of tillage intensity on changes of microbiological activity and content of particulate organic matter in soil under winter wheat duirng 3 years was studied. Microbial response related to the tillage-induced changes in soil determined on the content of biomass C and N, the rate of CO2 evolution, B/F ratio, the activity of dehydrogenases, acid and alkaline phosphatases, soil C/N ratio and microbial biomass C/N ratio confirmed the high sensitivity of soil microbial populations to the tillage system applied. After three year studies, the direct sowing system enhanced the increase of labile fraction of organic matter content in soil. There were no significant changes in the labile fraction quantity observed in soil under conventional tillage. Similar response related to the tillage intensity was observed in particulate organic matter quantities expressed as a percentage of total organic matter in soil. A high correlation coefficients calculated between contents of soil microbial biomass C and N, particulate organic matter and potentially mineralizable N, and the obtained yields of winter wheat grown on experimental fields indicated on a high importance of biological quality of status of soil for agricultural crop production.

  2. Evaluation of residue management practices effects on corn productivity, soil quality, and greenhouse gas emissions

    NASA Astrophysics Data System (ADS)

    Guzman, Jose German

    The removal of crop residues left after harvest is being considered as a potential feedstock source for bioethanol production which can contribute to the reduction of fossil fuel use and net greenhouse gas (GHG). The objectives of this study were to: (i) examine how tillage, N fertilization rates, residue removal, and their interactions affect crop productivity, (ii) SOC and soil physical properties, and (iii) GHG emissions, and (iv) calculated a soil C budget to determine how much crop residue can be sustainably be removed in Central and Southwest Iowa. After three years of residue removal under different management practices, the findings of this study suggest that a portion of the corn residue that is left on the soil surface after harvest can be removed, with no negative impacts in the short term continuous corn yield in sites at Central and Southwest Iowa. However, significant decreases in SOC sequestration rates, microbial biomass-C, bulk density, soil penetration resistance, wet aggregate stability, and infiltration rates were observed, but varied with soil type and management practices. Additionally, soil surface CO2 and N2O emissions were responsive to management practices; primarily by altering soil temperature, soil water content, soil mineral N, and crop growth. Results from soil C budget show that in 2010 when corn growth was not water stressed (lack of moisture), approximately 35 and 30% of the residue could be sustainably removed in the Central and Southwest sites, respectively. In 2011, drier soil conditions resulted in approximately 2 and 49% of the residue could be sustainably removed in the Central and Southwest sites, respectively.

  3. Solid-phase microextraction-gas chromatographic determination of volatile monoaromatic hydrocarbons in soil.

    PubMed

    Zygmunt, B; Namiesnik, J

    2001-08-01

    Benzene, toluene, ethylbenzene, three isomers of xylene, and cumene have been isolated and enriched from soil samples by a combination of water extraction at room and elevated temperature and headspace-solid-phase microextraction before their gas chromatographic-mass spectrometric (GC-MS) determination. The conditions used for all stages of sample preparation and chromatographic analysis were optimized. Analytes sampled on a polydimethylsiloxane-coated solid-phase microextraction fiber were thermally desorbed in the split/splitless injector of a gas chromatograph (GC) coupled with a mass spectrometer (MS). The desorption temperature was optimized. The GC separation was performed in a capillary column. Detection limits were found to be of the order of ca. 1 ng g(-1). Relative recoveries of the analytes from soils were found to be highly dependent on soil organic-matter content and on compound identity; they ranged from ca 92 to 96% for sandy soil (extraction at room temperature) and from ca 27 to 55% for peaty soil (extraction at elevated temperature). A few real-world soil samples were analyzed; the individual monoaromatic hydrocarbon content ranged from below detection limits to 6.4 ng g(-1) for benzene and 8.1 for the total of p- + m-xylene.

  4. Assessment of soil-gas and soil contamination at the Old Metal Workshop Hog Farm Area, Fort Gordon, Georgia, 2009-2010

    USGS Publications Warehouse

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

    2011-01-01

    Soil gas and soil were assessed for contaminants at the Old Metal Workshop Hog Farm Area at Fort Gordon, Georgia, from October 2009 to September 2010. The assessment included delineating organic contaminants present in soil-gas and inorganic contaminants present in soil samples collected from the area estimated to be the Old Metal Workshop Hog Farm Area. This assessment was conducted to provide environmental contamination data to Fort Gordon personnel pursuant to requirements for the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. All soil-gas samplers contained total petroleum hydrocarbons above the method detection level. The highest total petroleum hydrocarbon mass detected was 121.32 micrograms in a soil-gas sampler from the western corner of the Old Metal Workshop Hog Farm Area along Sawmill Road. The highest undecane mass detected was 73.28 micrograms at the same location as the highest total petroleum hydrocarbon mass. Some soil-gas samplers detected toluene mass greater than the method detection level of 0.02 microgram; the highest detection of toluene mass was 0.07 microgram. Some soil-gas samplers were installed in areas of high-contaminant mass to assess for explosives and chemical agents. Explosives or chemical agents were not detected above their respective method detection levels for all soil-gas samplers installed. Inorganic concentrations in five soil samples collected did not exceed regional screening levels established by the U.S. Environmental Protection Agency. Barium concentrations, however, were up to eight times higher than the background concentrations reported in similar Coastal Plain sediments of South Carolina.

  5. Relative gas diffusivity as a controller of soil N2 and N2O fluxes

    NASA Astrophysics Data System (ADS)

    Clough, Tim; Balaine, Nimlesh; Beare, Mike; Thomas, Steve

    2015-04-01

    Animal grazing may induce soil compaction and has been shown to enhance emissions of the greenhouse gas nitrous oxide (N2O). The dominant substrate for N2O production is urea, supplied to the soil in ruminant urine. While studies have examined the effects of water-filled pore space on N2O emissions there has been less attention paid to the role of soil physical properties, such as relative gas diffusivity (Dp/Do), on N2O emissions and associated emissions of dinitrogen (N2). Three experiments were performed on soil cores maintained at a range of soil bulk densities (1.1 to 1.5 Mg/m3) and soil matric potentials (-10 to -0.2 kPa). These soil cores received urea at 700 kg N/ha to simulate a urine deposition event. Using the 15N tracer technique we measured N2 and N2O fluxes in order to investigate the role of soil Dp/Do as a controlling factor the magnitude of N2 and N2O fluxes and the reduction of N2O. As soil compaction and soil moisture contents increased soil Dp/Do declined. This in turn resulted in slower rates of nitrification. The mean cumulative fluxes of N2O, as a percentage of N applied, ranged from <1 to 16% after 35 days. Cumulative N2 fluxes as a percentage of N applied, ranged from <1 to 60% after 35 days. Soil compaction and soil matric potential interacted to influence Dp/Do which in turn was seen to be a strong determinant of the magnitude of both N2O and N2 fluxes. As Dp/Do values decreased a critical value was reached where N2O fluxes rapidly switched from being at a maximum to a minimum while at the same time N2 production intensified. This was also reflected in the N2:N2O ratios, based on cumulative fluxes, which ranged from <1 to 25. When compared with water-filled pore space the Dp/Do variable proved to be a better predictor of the switch from N2O production to N2 production.

  6. SMOS Soil moisture Cal val activities

    NASA Astrophysics Data System (ADS)

    Kerr, Y.; Mialon, A.; Bitar, A. Al; Leroux, D.; Richaume, P.; Gruhier, C.; Berthon, L.; Novello, N.; Rudiger, C.; Bircher, S.; Wigneron, J. P.; Ferrazzoli, P.; Rahmoune, R.

    2012-04-01

    SMOS, successfully launched on November 2, 2009, uses an L Band radiometer with aperture synthesis to achieve a good spatial resolution.. It was developed and made under the leadership of the European Space Agency (ESA) as an Earth Explorer Opportunity mission. It is a joint program with the Centre National d'Etudes Spatiales (CNES) in France and the Centro para el Desarrollo Tecnologico Industrial (CDTI) in Spain. SMOS carries a single payload, an L band 2D interferometric,radiometer in the 1400-1427 MHz protected band. This wavelength penetrates well through the vegetation and with the atmosphere being almost transparent, it enables us to infer both soil moisture and vegetation water content. SMOS achieves an unprecedented spatial resolution of 50 km at L-band maximum (43 km on average) with multi angular-dual polarized (or fully polarized) brightness temperatures over the globe and with a revisit time smaller than 3 days. SMOS is now acquiring data and has undergone the commissioning phase. The data quality exceeds what was expected, showing very good sensitivity and stability. The data is however very much impaired by man made emission in the protected band, leading to degraded measurements in several areas including parts of Europe and China. Many different international teams are now performing cal val activities in various parts of the world, with notably large field campaigns either on the long time scale or over specific targets to address the specific issues. These campaigns take place in various parts of the world and in different environments, from the Antarctic plateau to the deserts, from rain forests to deep oceans. SMOS is a new sensor, making new measurements and paving the way for new applications. It requires a detailed analysis of the data so as to validate both the approach and the quality of the retrievals, and allow for monitoring and the evolution of the sensor. To achieve such goals it is very important to link efficiently ground

  7. Effects of tillage on the Fe oxides activation in soil

    NASA Astrophysics Data System (ADS)

    Chi, Guangyu; Chen, Xin; Shi, Yi; Wang, Jun; Zheng, Taihui

    2009-07-01

    Since mid-1950s, the wetland ecosystems in Sanjiang Plain of Northeast China have been experiencing greater changes in land use, which had negative effects on the soil environments. This study assessed the effects of soil tillage on the activation of soil Fe in the region. The test ecosystems included natural wetland, paddy field and upland field converted from wetland. Soil samples at the depths of 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, 40-60 cm, 60-90 cm and 90-120 cm were collected from each of the ecosystems for the analysis of vertical distribution of soil pH, organic carbon, chelate Fe oxides and Fe(II). The results showed that the conversion of wetland into paddy field and upland field induced a decrease of organic carbon content in 0-10 cm soil layer by 61.8% (P <0.05) and 70.0% (P < 0.05), respectively. The correlations among iron forms and soil organic carbon showed that chelate Fe oxides and Fe(II) was correlated positively with soil organic carbon and chelate ratio had a more positive relationship with organic carbon than chelate Fe oxides and Fe(II). The results of chelate Fe oxides, Fe(II) and chelate ratio of Fe suggested that reclamation could prevent the Fe activation and organic matter is credited for having an important influence on the process of Fe activation.

  8. Measurement of greenhouse gas flux from agricultural soils using static chambers.

    PubMed

    Collier, Sarah M; Ruark, Matthew D; Oates, Lawrence G; Jokela, William E; Dell, Curtis J

    2014-08-03

    Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the biogeochemical drivers of climate change and to the development and evaluation of GHG mitigation strategies based on modulation of landscape management practices. The static chamber-based method described here is based on trapping gases emitted from the soil surface within a chamber and collecting samples from the chamber headspace at regular intervals for analysis by gas chromatography. Change in gas concentration over time is used to calculate flux. This method can be utilized to measure landscape-based flux of carbon dioxide, nitrous oxide, and methane, and to estimate differences between treatments or explore system dynamics over seasons or years. Infrastructure requirements are modest, but a comprehensive experimental design is essential. This method is easily deployed in the field, conforms to established guidelines, and produces data suitable to large-scale GHG emissions studies.

  9. Mississippi exploration field trials using microbial, radiometrics, free soil gas, and other techniques

    SciTech Connect

    Moody, J.S.; Brown, L.R.; Thieling, S.C.

    1995-12-31

    The Mississippi Office of Geology has conducted field trials using the surface exploration techniques of geomicrobial, radiometrics, and free soil gas. The objective of these trials is to determine if Mississippi oil and gas fields have surface hydrocarbon expression resulting from vertical microseepage migration. Six fields have been surveyed ranging in depth from 3,330 ft to 18,500 ft. The fields differ in trapping styles and hydrocarbon type. The results so far indicate that these fields do have a surface expression and that geomicrobial analysis as well as radiometrics and free soil gas can detect hydrocarbon microseepage from pressurized reservoirs. All three exploration techniques located the reservoirs independent of depth, hydrocarbon type, or trapping style.

  10. Measurement of Greenhouse Gas Flux from Agricultural Soils Using Static Chambers

    PubMed Central

    Collier, Sarah M.; Ruark, Matthew D.; Oates, Lawrence G.; Jokela, William E.; Dell, Curtis J.

    2014-01-01

    Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the biogeochemical drivers of climate change and to the development and evaluation of GHG mitigation strategies based on modulation of landscape management practices. The static chamber-based method described here is based on trapping gases emitted from the soil surface within a chamber and collecting samples from the chamber headspace at regular intervals for analysis by gas chromatography. Change in gas concentration over time is used to calculate flux. This method can be utilized to measure landscape-based flux of carbon dioxide, nitrous oxide, and methane, and to estimate differences between treatments or explore system dynamics over seasons or years. Infrastructure requirements are modest, but a comprehensive experimental design is essential. This method is easily deployed in the field, conforms to established guidelines, and produces data suitable to large-scale GHG emissions studies. PMID:25146426

  11. Soil microbial activities beneath Stipa tenacissima L. and in surrounding bare soil

    NASA Astrophysics Data System (ADS)

    Novosadová, I.; Ruiz Sinoga, J. D.; Záhora, J.; Fišerová, H.

    2010-05-01

    Open steppes dominated by Stipa tenacissima L. constitute one of the most representative ecosystems of the semi-arid zones of Eastern Mediterranean Basin (Iberian Peninsula, North of Africa). These steppes show a higher degree of variability in composition and structure. Ecosystem functioning is strongly related to the spatial pattern of grass tussocks. Soils beneath S. tenacissima grass show higher fertility and improved microclimatic conditions, favouring the formation of "resource islands" (Maestre et al., 2007). On the other hand in "resource islands" and in surrounding bare soil exists the belowground zone of influence. The competition for water and resources between plants and microorganisms is strong and mediated trough an enormous variety of exudates and resource depletion intended to regulate soil microbial communities in the rhizosphere, control herbivory, encourage beneficial symbioses, and change chemical and physical properties in soil (Pugnaire et Armas, 2008). Secondary compounds and allelopathy restrict other species growth and contribute to patchy plant distribution. Active root segregation affects not only neighbourś growth but also soil microbial activities. The objective of this study was to assess the effect of Stipa tenacissima on the key soil microbial activities under controlled incubation conditions (basal and potential respiration; net nitrogen mineralization). The experimental plots were located in the province Almería in Sierra de los Filabres Mountains near the village Gérgal (southeast Spain) in the small catchment which is situated between 1090 - 1165 m a.s.l. The area with extent of 82 000 m2 is affected by soil degradation. The climate is semiarid Mediterranean. The mean annual rainfall is of about 240 mm mostly concentrated in autumn and spring. The mean annual temperature is 13.9° C. The studied soil has a loam to sandy clay texture and is classified as Lithosol (FAO-ISRIC and ISSS, 1998). The vegetation of these areas is an

  12. ACTIVE SOIL DEPRESSURIZATION (ASD) DEMONSTRATION IN A LARGE BUILDING

    EPA Science Inventory

    The report gives results of an evaluation of the feasibility of implementing radon resistant construction techniques -- especially active soil depressurization (ASD) -- in new large buildings in Florida. Indoor radon concentrations and radon entry were monitored in a finished bui...

  13. A blue carbon soil database: Tidal wetland stocks for the US National Greenhouse Gas Inventory

    NASA Astrophysics Data System (ADS)

    Feagin, R. A.; Eriksson, M.; Hinson, A.; Najjar, R. G.; Kroeger, K. D.; Herrmann, M.; Holmquist, J. R.; Windham-Myers, L.; MacDonald, G. M.; Brown, L. N.; Bianchi, T. S.

    2015-12-01

    Coastal wetlands contain large reservoirs of carbon, and in 2015 the US National Greenhouse Gas Inventory began the work of placing blue carbon within the national regulatory context. The potential value of a wetland carbon stock, in relation to its location, soon could be influential in determining governmental policy and management activities, or in stimulating market-based CO2 sequestration projects. To meet the national need for high-resolution maps, a blue carbon stock database was developed linking National Wetlands Inventory datasets with the USDA Soil Survey Geographic Database. Users of the database can identify the economic potential for carbon conservation or restoration projects within specific estuarine basins, states, wetland types, physical parameters, and land management activities. The database is geared towards both national-level assessments and local-level inquiries. Spatial analysis of the stocks show high variance within individual estuarine basins, largely dependent on geomorphic position on the landscape, though there are continental scale trends to the carbon distribution as well. Future plans including linking this database with a sedimentary accretion database to predict carbon flux in US tidal wetlands.

  14. Degassing behavior of Mt. Etna volcano (Italy) during 2007-2008, inferred by crater plume and soil gas measurements.

    NASA Astrophysics Data System (ADS)

    Salerno, G. G.; Caltabiano, T.; Giammanco, S.; Burton, M.; La Spina, A.; Lopez, M.; Randazzo, D.; Bruno, N.; Longo, E.; Murè, F.

    2009-04-01

    Studies on volcanic degassing have recently shown the important role of volatile release from active volcanoes in understanding magmatic processes prior to eruptions. Here we present and discuss the evolution of magmatic degassing that preceded and accompanied the 2008 Mt. Etna eruption. We tracked the ascent of magma bodies by high-temporal resolution measurements of SO2 emission rates and discrete sampling of SO2/HCl and SO2/HF molar ratios in the crater plume, as well as by periodic measurement of soil CO2 emission rates. Our data suggest that the first signs of upward migration of gas-rich magma before the 2008 eruption were observed in June 2007, indicated by a strong increase in soil CO2 efflux followed by a slow declining trend in SO2 flux and halogens. This degassing behavior preceded the mid-August 2007 summit activity culminated with the September 4th paroxysmal event. Five months later, a new increase in both soil CO2 and SO2 emission rates occurred before the November 23rd paroxysm, to drop down in late December. In the following months, geochemical parameters showed high variability, characterized by isolated sudden increases occurred in early December 2007 and late March 2008. In early May soil CO2, SO2 emission rates and S/Cl molar ratio gradually increased. Crater degassing peaked on May 13th marking the onset of the eruption. Eruptive activity was accompanied by a general steady-state of SO2 flux characterized by two main degassing cycles. These cycles preceded explosive activity at the eruptive vents, indicating terminal new-arrival of deep gas-rich magma bodies in the shallow plumbing system of Mt Etna. Conversely, halogens described a slight increasing trend till the end of 2008. These observations suggest an impulsive syn-eruptive dynamics of magma transfer from depth to the surface. Differently from the SO2 emission rates, the S/Cl ratio and the soil CO2 efflux values showed an increasing trend from mid-April to mid-July 2008, indicating

  15. Spatial Variations of Soil Microbial Activities in Saline Groundwater-Irrigated Soil Ecosystem

    NASA Astrophysics Data System (ADS)

    Chen, Li-Juan; Feng, Qi; Li, Chang-Sheng; Song, You-Xi; Liu, Wei; Si, Jian-Hua; Zhang, Bao-Gui

    2016-05-01

    Spatial variations of soil microbial activities and its relationship with environmental factors are very important for estimating regional soil ecosystem function. Based on field samplings in a typical saline groundwater-irrigated region, spatial variations of soil microbial metabolic activities were investigated. Combined with groundwater quality analysis, the relationship between microbial activities and water salinity was also studied. The results demonstrated that moderate spatial heterogeneity of soil microbial activities presented under the total dissolved solids (TDS) of groundwater ranging from 0.23 to 12.24 g L-1. Groundwater salinity and microbial activities had almost opposite distribution characteristics: slight saline water was mainly distributed in west Baqu and south Quanshan, while severe saline and briny water were dominant in east Baqu and west Huqu; however, total AWCD was higher in the east-center and southwest of Baqu and east Huqu, while it was lower in east Baqu and northwest Huqu. The results of correlation analyses demonstrated that high-salinity groundwater irrigation had significantly adverse effects on soil microbial activities. Major ions Ca2+, Mg2+, Cl_, and SO4 2- in groundwater decisively influenced the results. Three carbon sources, carbohydrates, amines, and phenols, which had minor utilization rates in all irrigation districts, were extremely significantly affected by high-salinity groundwater irrigation. The results presented here offer an approach for diagnosing regional soil ecosystem function changes under saline water irrigation.

  16. Spatial Variations of Soil Microbial Activities in Saline Groundwater-Irrigated Soil Ecosystem.

    PubMed

    Chen, Li-Juan; Feng, Qi; Li, Chang-Sheng; Song, You-Xi; Liu, Wei; Si, Jian-Hua; Zhang, Bao-Gui

    2016-05-01

    Spatial variations of soil microbial activities and its relationship with environmental factors are very important for estimating regional soil ecosystem function. Based on field samplings in a typical saline groundwater-irrigated region, spatial variations of soil microbial metabolic activities were investigated. Combined with groundwater quality analysis, the relationship between microbial activities and water salinity was also studied. The results demonstrated that moderate spatial heterogeneity of soil microbial activities presented under the total dissolved solids (TDS) of groundwater ranging from 0.23 to 12.24 g L(-1). Groundwater salinity and microbial activities had almost opposite distribution characteristics: slight saline water was mainly distributed in west Baqu and south Quanshan, while severe saline and briny water were dominant in east Baqu and west Huqu; however, total AWCD was higher in the east-center and southwest of Baqu and east Huqu, while it was lower in east Baqu and northwest Huqu. The results of correlation analyses demonstrated that high-salinity groundwater irrigation had significantly adverse effects on soil microbial activities. Major ions Ca(2+), Mg(2+), Cl(-), and SO4(2-) in groundwater decisively influenced the results. Three carbon sources, carbohydrates, amines, and phenols, which had minor utilization rates in all irrigation districts, were extremely significantly affected by high-salinity groundwater irrigation. The results presented here offer an approach for diagnosing regional soil ecosystem function changes under saline water irrigation.

  17. [Degradation of phthalate esters in soil and the effects on soil enzyme activities].

    PubMed

    Zhang, Jian; Shi, Yi-Jing; Cui, Yin; Xie, Hui-Jun; Wang, Wen-Xing

    2010-12-01

    Phthalate esters (PAEs) are a kind of widespread toxic organic compounds in the environment. We discussed the different degradation rate of four kinds of PAEs in the soil and its impact on different soil enzyme activities. We used GC-MS methods to determine the concentration of PAEs in soil. The results showed that soil microorganisms play a major role in the degradation of PAEs. The biodegradation diagram of PAEs was accord with first-order kinetics equation. And the shorter carbon chain, the better degradation efficiency. With the high concentration of PAE30, DnOP, which has long carbon chain, the degradation efficiency is lower than that of PAE1 and PAE10, only 73% was degraded after 40 days. We use standard methods to determine the matrix enzyme activities, after adding the PAEs into soil, beta-glucosidase, phosphatase, urease, protease activity have changed. Phosphatase activity decreased at first and then increased, beta-glucosidase activity decreased slowly, protease activity increased at first and then decreased, the activity of urease increased gradually. After 20 days, except for beta-glucosidase activity continued decreasing, the activities of others enzyme recovered gradually, and higher than the control group.

  18. Effects of conventional and no-tillage soil management and compost and sludge amendment on soil CO2 fluxes and microbial activities

    NASA Astrophysics Data System (ADS)

    Garcia-Gil, Juan Carlos; Haller, Isabel; Soler-Rovira, Pedro; Polo, Alfredo

    2010-05-01

    Soil management exerts a significant influence on the dynamic of soil organic matter, which is a key issue to enhance soil quality and its ecological functions, but also affects to greenhouse gas emissions and C sequestration processes. The objective of the present research was to determine the influence of soil management (conventional deep-tillage and no-tillage) and the application of two different organic amendment -thermally-dry sewage sludge (TSL) and municipal waste compost (MWC)- on soil CO2 fluxes and microbial activities in a long-term field experiment under semi-arid conditions. Both organic amendments were applied at a rate of 30 t ha-1 prior to sowing a barley crop. The experiment was conducted on an agricultural soil (Calcic Luvisol) from the experimental farm "La Higueruela" (Santa Olalla, Toledo). Unamended soils were used as control in both conventional and no-tillage management. During the course of the experiment, soil CO2 fluxes, microbial biomass C (MBC) and enzyme activities involved in the biogeochemical cycles of C, N and P were monitored during 12 months. The results obtained during the experiment for soil CO2 fluxes showed a great seasonal fluctuation due to semi-arid climate conditions. Overall, conventional deep-tillage soils exhibited higher CO2 fluxes, which was particularly larger during the first hours after deep-tillage was performed, and smaller MBC content and significantly lower dehydrogenase, beta-glucosidase, phosphatase, urease and BAA protease activities than no-tillage soils. Both MWC and TSL amendments provoked a significant increase of CO2 fluxes in both conventional and no-tillage soils, which was larger in TSL amended soils and particularly in no-tillage soils. The application of these organic amendments also enhanced MBC content and the overall enzyme activities in amended soils, which indicate a global revitalization of soil microbial metabolism in response to the fresh input of organic compounds that are energy

  19. Fast volatile organic compound recovery from soil standards for analysis by thermal desorption gas chromatography.

    PubMed

    Meniconi, Maria de Fátima Guadalupe; Parris, R; Thomas, C L P

    2003-10-01

    The development of high-throughput environmental screening assays are needed to meet high-specification data quality objectives (DQOs) that require large numbers of samples to be taken and analysed rapidly. The acquisition and stabilisation of the sample is a key technical and operational challenge in analytical sequences associated with the determination of volatile organic compound (VOC) contamination of soils. Further the development of miniaturised and embedded analytical systems for environmental conditioning monitoring requires the development of new sampling techniques. A proof-of-concept study is described that shows how pressurised gas, in this case carbon dioxide, may be used to recover reversibly-bound VOCs from soil into an adsorbent sampler, and then analysed by thermal desorption-gas chromatography. The effects of the volume of the pressurised gas, the gas flow rate and the mass of the soil sample on the recovery efficiency and breakthrough from the adsorbent trap were investigated in a preliminary characterisation study. Two distinct approaches were identified. The first involved ventilation of the voids within the soil matrix to displace the soil-gas headspace, a rapid screening approach. The second involved a more prolonged purge of the matrix to strip reversibly bound species into the gas phase and hence pass them into the adsorbent trap, a purge and trap approach. The shortest possible sample processing time required to yield analytically useful responses was 5 s with the use of the headspace approach. In this case n-octane, benzene and toluene were recovered from conditioned spiked soil samples at concentrations in the range 42 to 1690 mg kg(-1). The limit of detection for the system was estimated to be no greater than 1.2 mg kg(-1). Using the purge and trap variant enabled recovery efficiencies greater than 93% to be achieved with liquid spikes of n-octane onto soil samples. These preliminary studies showed that a system based on this approach

  20. Soil greenhouse gas fluxes during wetland forest retreat along the Lower Savannah River, Georgia (USA)

    USGS Publications Warehouse

    Krauss, Ken W.; Whitbeck, Julie L.

    2012-01-01

    Tidal freshwater forested wetlands (tidal swamps) are periodically affected by salinity intrusion at seaward transitions with marsh, which, along with altered hydrology, may affect the balance of gaseous carbon (C) and nitrogen (N) losses from soils. We measured greenhouse gas emissions (CO2, CH4, N2O) from healthy, moderately degraded, and degraded tidal swamp soils undergoing sea-level-rise-induced retreat along the lower Savannah River, Georgia, USA. Soil CO2 flux ranged from 90.2 to 179.1 mg CO2 m-2 h-1 among study sites, and was the dominant greenhouse gas emitted. CO2 flux differed among sites in some months, while CH4 and N2O fluxes were 0.18 mg CH4 m-2 h-1 and 1.23 μg N2O m-2 h-1, respectively, with no differences among sites. Hydrology, soil temperature, and air temperature, but not salinity, controlled the annual balance of soil CO2 emissions from tidal swamp soils. No clear drivers were found for CH4 or N2O emissions. On occasion, large ebbing or very low tides were even found to draw CO2 fluxes into the soil (dark CO2 uptake), along with CH4 and N2O. Overall, we hypothesized a much greater role for salinity and site condition in controlling the suite of greenhouse gases emitted from tidal swamps than we discovered, and found that CO2 emissions–not CH4 or N2O–contributed most to the global warming potential from these tidal swamp soils.

  1. Soil greenhouse gas fluxes during wetland forest retreat along the lower Savannah River, Georgia (USA)

    USGS Publications Warehouse

    Krauss, Ken W.; Whitbeck, Julie L.

    2012-01-01

    Tidal freshwater forested wetlands (tidal swamps) are periodically affected by salinity intrusion at seaward transitions with marsh, which, along with altered hydrology, may affect the balance of gaseous carbon (C) and nitrogen (N) losses from soils. We measured greenhouse gas emissions (CO2, CH4, N2O) from healthy, moderately degraded, and degraded tidal swamp soils undergoing sea-level-rise-induced retreat along the lower Savannah River, Georgia, USA. Soil CO2 flux ranged from 90.2 to 179.1 mg CO2 m-2 h-1 among study sites, and was the dominant greenhouse gas emitted. CO2 flux differed among sites in some months, while CH4 and N2O fluxes were 0.18 mg CH4 m-2 h-1 and 1.23 μg N2O m-2 h-1, respectively, with no differences among sites. Hydrology, soil temperature, and air temperature, but not salinity, controlled the annual balance of soil CO2 emissions from tidal swamp soils. No clear drivers were found for CH4 or N2O emissions. On occasion, large ebbing or very low tides were even found to draw CO2 fluxes into the soil (dark CO2 uptake), along with CH4 and N2O. Overall, we hypothesized a much greater role for salinity and site condition in controlling the suite of greenhouse gases emitted from tidal swamps than we discovered, and found that CO2 emissions-not CH4 or N2O-contributed most to the global warming potential from these tidal swamp soils.

  2. Fate and activity of microorganisms introduced into soil.

    PubMed Central

    van Veen, J A; van Overbeek, L S; van Elsas, J D

    1997-01-01

    Introduced microorganisms are potentially powerful agents for manipulation of processes and/or components in soil. Fields of application include enhancement of crop growth, protection of crops against plant-pathogenic organisms, stimulation of biodegradation of xenobiotic compounds (bioaugmentation), and improvement of soil structure. Inoculation of soils has already been applied for decades, but it has often yielded inconsistent or disappointing results. This is caused mainly by a commonly observed rapid decline in inoculant population activity following introduction into soil, i.e., a decline of the numbers of inoculant cells and/or a decline of the (average) activity per cell. In this review, we discuss the available information on the effects of key factors that determine the fate and activity of microorganisms introduced into soil, with emphasis on bacteria. The factors addressed include the physiological status of the inoculant cells, the biotic and abiotic interactions in soil, soil properties, and substrate availability. Finally, we address the possibilities available to effectively manipulate the fate and activity of introduced microorganisms in relation to the main areas of their application. PMID:9184007

  3. Fate and activity of microorganisms introduced into soil.

    PubMed

    van Veen, J A; van Overbeek, L S; van Elsas, J D

    1997-06-01

    Introduced microorganisms are potentially powerful agents for manipulation of processes and/or components in soil. Fields of application include enhancement of crop growth, protection of crops against plant-pathogenic organisms, stimulation of biodegradation of xenobiotic compounds (bioaugmentation), and improvement of soil structure. Inoculation of soils has already been applied for decades, but it has often yielded inconsistent or disappointing results. This is caused mainly by a commonly observed rapid decline in inoculant population activity following introduction into soil, i.e., a decline of the numbers of inoculant cells and/or a decline of the (average) activity per cell. In this review, we discuss the available information on the effects of key factors that determine the fate and activity of microorganisms introduced into soil, with emphasis on bacteria. The factors addressed include the physiological status of the inoculant cells, the biotic and abiotic interactions in soil, soil properties, and substrate availability. Finally, we address the possibilities available to effectively manipulate the fate and activity of introduced microorganisms in relation to the main areas of their application.

  4. A new estimation of global soil greenhouse gas fluxes using a simple data-oriented model.

    PubMed

    Hashimoto, Shoji

    2012-01-01

    Soil greenhouse gas fluxes (particularly CO(2), CH(4), and N(2)O) play important roles in climate change. However, despite the importance of these soil greenhouse gases, the number of reports on global soil greenhouse gas fluxes is limited. Here, new estimates are presented for global soil CO(2) emission (total soil respiration), CH(4) uptake, and N(2)O emission fluxes, using a simple data-oriented model. The estimated global fluxes for CO(2) emission, CH(4) uptake, and N(2)O emission were 78 Pg C yr(-1) (Monte Carlo 95% confidence interval, 64-95 Pg C yr(-1)), 18 Tg C yr(-1) (11-23 Tg C yr(-1)), and 4.4 Tg N yr(-1) (1.4-11.1 Tg N yr(-1)), respectively. Tropical regions were the largest contributor of all of the gases, particularly the CO(2) and N(2)O fluxes. The soil CO(2) and N(2)O fluxes had more pronounced seasonal patterns than the soil CH(4) flux. The collected estimates, including both the previous and the present estimates, demonstrate that the means of the best estimates from each study were 79 Pg C yr(-1) (291 Pg CO(2) yr(-1); coefficient of variation, CV = 13%, N = 6) for CO(2), 21 Tg C yr(-1) (29 Tg CH(4) yr(-1); CV = 24%, N = 24) for CH(4), and 7.8 Tg N yr(-1) (12.2 Tg N(2)O yr(-1); CV = 38%, N = 11) for N(2)O. For N(2)O, the mean of the estimates that was calculated by excluding the earliest two estimates was 6.6 Tg N yr(-1) (10.4 Tg N(2)O yr(-1); CV = 22%, N = 9). The reported estimates vary and have large degrees of uncertainty but their overall magnitudes are in general agreement. To further minimize the uncertainty of soil greenhouse gas flux estimates, it is necessary to build global databases and identify key processes in describing global soil greenhouse gas fluxes.

  5. Distribution and activity of anaerobic ammonium-oxidising bacteria in natural freshwater wetland soils.

    PubMed

    Shen, Li-dong; Wu, Hong-sheng; Gao, Zhi-qiu; Cheng, Hai-xiang; Li, Ji; Liu, Xu; Ren, Qian-qi

    2016-04-01

    Anaerobic ammonium oxidation (anammox) process plays a significant role in the marine nitrogen cycle. However, the quantitative importance of this process in nitrogen removal in wetland systems, particularly in natural freshwater wetlands, is still not determined. In the present study, we provided the evidence of the distribution and activity of anammox bacteria in a natural freshwater wetland, located in southeastern China, by using (15)N stable isotope measurements, quantitative PCR assays and 16S rRNA gene clone library analysis. The potential anammox rates measured in this wetland system ranged between 2.5 and 25.5 nmol N2 g(-1) soil day(-1), and up to 20% soil dinitrogen gas production could be attributed to the anammox process. Phylogenetic analysis of 16S rRNA genes showed that anammox bacteria related to Candidatus Brocadia, Candidatus Kuenenia, Candidatus Anammoxoglobus and two novel anammox clusters coexisted in the collected soil cores, with Candidatus Brocadia and Candidatus Kuenenia being the dominant anammox genera. Quantitative PCR of hydrazine synthase genes showed that the abundance of anammox bacteria varied from 2.3 × 10(5) to 2.2 × 10(6) copies g(-1) soil in the examined soil cores. Correlation analyses suggested that the soil ammonium concentration had significant influence on the activity of anammox bacteria. On the basis of (15)N tracing technology, it is estimated that a total loss of 31.1 g N m(-2) per year could be linked the anammox process in the examined wetland.

  6. No tillage and liming reduce greenhouse gas emissions from poorly drained agricultural soils in Mediterranean regions.

    PubMed

    García-Marco, Sonia; Abalos, Diego; Espejo, Rafael; Vallejo, Antonio; Mariscal-Sancho, Ignacio

    2016-10-01

    No tillage (NT) has been associated to increased N2O emission from poorly drained agricultural soils. This is the case for soils with a low permeable Bt horizon, which generates a perched water layer after water addition (via rainfall or irrigation) over a long period of time. Moreover, these soils often have problems of acidity and require liming application to sustain crop productivity; changes in soil pH have large implications for the production and consumption of soil greenhouse gas (GHG) emissions. Here, we assessed in a split-plot design the individual and interactive effects of tillage practices (conventional tillage (CT) vs. NT) and liming (Ca-amendment vs. not-amendment) on N2O and CH4 emissions from poorly drained acidic soils, over a field experiment with a rainfed triticale crop. Soil mineral N concentrations, pH, temperature, moisture, water soluble organic carbon, GHG fluxes and denitrification capacity were measured during the experiment. Tillage increased N2O emissions by 68% compared to NT and generally led to higher CH4 emissions; both effects were due to the higher soil moisture content under CT plots. Under CT, liming reduced N2O emissions by 61% whereas no effect was observed under NT. Under both CT and NT, CH4 oxidation was enhanced after liming application due to decreased Al(3+) toxicity. Based on our results, NT should be promoted as a means to improve soil physical properties and concurrently reduce N2O and CH4 emissions. Raising the soil pH via liming has positive effects on crop yield; here we show that it may also serve to mitigate CH4 emissions and, under CT, abate N2O emissions.

  7. 78 FR 59650 - Subzone 9F, Authorization of Production Activity, The Gas Company, LLC dba Hawai'i Gas...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-27

    ... Foreign-Trade Zones Board Subzone 9F, Authorization of Production Activity, The Gas Company, LLC dba Hawai'i Gas, (Synthetic Natural Gas), Kapolei, Hawaii On May 22, 2013, The Gas Company, LLC dba Hawai'i Gas submitted a notification of proposed production activity to the Foreign-Trade Zones (FTZ)...

  8. Radon concentration in soil gas: a comparison of the variability resulting from different methods, spatial heterogeneity and seasonal fluctuations.

    PubMed

    Winkler, R; Ruckerbauer, F; Bunzl, K

    2001-05-14

    From the end of 1996 through March 1999, the spatial and temporal variability of the soil 222Rn concentration was investigated at a 20 m x 20 m test field with porous soil in 0.5 m and 1.0 m depth at nine positions each and at 1 m x 1 m plots at four positions each. For this, soil gas was collected weekly into evacuated scintillation cells and was analysed subsequently for radon activity. In the 20 m x 20 m field the spatial variability was characterized by coefficients of variation (C.V.) of 26% at 0.5 m, and 13% at 1.0 m depth. Within the 1 m x 1 m plots the C.V. values were 4% and 2%, i.e. within the uncertainty of the method. Time series analysis (TSA) of the soil radon data shows seasonal variations with maximum concentrations in the winter months. Radon concentrations ranged from 6 to 50 kBq m(-3) in 0.5 m depth, and from 8 to 34 kBq m(-3) in 1.0 m depth. Mostly, the concentrations were higher in 0.5 depth than in 1.0 m depth. However, seasonal variation of the 0.5 m to the 1.0 m concentration ratio has been verified by TSA. To test the variability resulting from different methods, additional procedures and instruments were investigated at the 20 m x 20 m field and at a second test field with a different soil type. Soil gas sampling into evacuated scintillation cells was selected as the reference procedure. Soil radon concentrations obtained with the different sampling procedures and detection methods at the 20 m x 20 m field essentially agreed within the limits of uncertainty of the methods tested. At the second test field, i.e. in a largely impermeable soil, deviations up to a factor of two related to the reference procedure were observed.

  9. [Effects of understory removal on soil greenhouse gas emissions in Carya cathayensis stands].

    PubMed

    Liu, Juan; Chen, Xue-shuang; Wu, Jia-sen; Jiang, Pei-kun; Zhou, Guo-mo; Li, Yong-fu

    2015-03-01

    CO2, N2O and CH4 are important greenhouse gases, and soils in forest ecosystems are their important sources. Carya cathayensis is a unique tree species with seeds used for high-grade dry fruit and oil production. Understory vegetation management plays an important role in soil greenhouse gases emission of Carya cathayensis stands. A one-year in situ experiment was conducted to study the effects of understory removal on soil CO2, N2O and CH4 emissions in C. cathayensis plantation by closed static chamber technique and gas chromatography method. Soil CO2 flux had a similar seasonal trend in the understory removal and preservation treatments, which was high in summer and autumn, and low in winter and spring. N2O emission occurred mainly in summer, while CH4 emission showed no seasonal trend. Understory removal significantly decreased soil CO, emission, increased N2O emission and CH4 uptake, but had no significant effect on soil water soluble organic carbon and microbial biomass carbon. The global warming potential of soil greenhouse gases emitted in the understory removal. treatment was 15.12 t CO2-e . hm-2 a-1, which was significantly lower than that in understory preservation treatment (17.04 t CO2-e . hm-2 . a-1).

  10. Activation of catalysts for synthesizing methanol from synthesis gas

    DOEpatents

    Blum, David B.; Gelbein, Abraham P.

    1985-01-01

    A method for activating a methanol synthesis catalyst is disclosed. In this method, the catalyst is slurried in an inert liquid and is activated by a reducing gas stream. The activation step occurs in-situ. That is, it is conducted in the same reactor as is the subsequent step of synthesizing methanol from a methanol gas stream catalyzed by the activated catalyst still dispersed in a slurry.

  11. [Effects of different fertilizer application on soil active organic carbon].

    PubMed

    Zhang, Rui; Zhang, Gui-Long; Ji, Yan-Yan; Li, Gang; Chang, Hong; Yang, Dian-Lin

    2013-01-01

    The variation characteristics of the content and components of soil active organic carbon under different fertilizer application were investigated in samples of calcareous fluvo-aquic soil from a field experiment growing winter wheat and summer maize in rotation in the North China Plain. The results showed that RF (recommended fertilization), CF (conventional fertilization) and NPK (mineral fertilizer alone) significantly increased the content of soil dissolved organic carbon and easily oxidized organic carbon by 24.92-38.63 mg x kg(-1) and 0.94-0.58 mg x kg(-1) respectively compared to CK (unfertilized control). The soil dissolved organic carbon content under OM (organic manure) increased greater than those under NPK and single fertilization, soil easily oxidized organic carbon content under OM and NPK increased greater than that under single chemical fertilization. OM and NPK showed no significant role in promoting the soil microbial biomass carbon, but combined application of OM and NPK significantly increased the soil microbial biomass carbon content by 36.06% and 20.69%, respectively. Soil easily oxidized organic carbon, dissolved organic carbon and microbial biomass carbon accounted for 8.41% - 14.83%, 0.47% - 0.70% and 0.89% - 1.20% of the total organic carbon (TOC), respectively. According to the results, the fertilizer application significantly increased the proportion of soil dissolved organic carbon and easily oxidized organic carbon, but there was no significant difference in the increasing extent of dissolved organic carbon. The RF and CF increased the proportion of soil easily oxidized organic carbon greater than OM or NPK, and significantly increased the proportion of microbial biomass carbon. OM or RF had no significant effect on the proportion of microbial biomass carbon. Therefore, in the field experiment, appropriate application of organic manure and chemical fertilizers played an important role for the increase of soil active organic carbon

  12. RESULTS FROM EPA FUNDED RESEARCH PROGRAMS ON THE IMPORTANCE OF PURGE VOLUME, SAMPLE VOLUME, SAMPLE FLOW RATE AND TEMPORAL VARIATIONS ON SOIL GAS CONCENTRATIONS

    EPA Science Inventory

    Two research studies funded and overseen by EPA have been conducted since October 2006 on soil gas sampling methods and variations in shallow soil gas concentrations with the purpose of improving our understanding of soil gas methods and data for vapor intrusion applications. Al...

  13. Sensing technologies to measure metabolic activities in soil and assess its health conditions

    NASA Astrophysics Data System (ADS)

    De Cesare, Fabrizio; Macagnano, Antonella

    2013-04-01

    (olfactory fingerprint) typical of the analysed air sample. Due to these features, we decided to apply such a sensing technology to the analyses of soil atmospheres, because several processes in soil, both abiotic and biotic, result in gas and/or volatile production and the dynamics of such releases may also be affected by several additional environmental factors, such as soil moisture, temperature, gas exchange rates with outer atmosphere, adsorption/desorption processes, etc. Then, the analysis of soil atmosphere may provide information about global soil conditions (e.g. soil quality and health), according to a holistic approach, where several factors are contemporarily taken into account. At the same time, the use of such a technology, if adequately trained on purpose, can supply information about a single or a pool of processes sharing similar features, which occur in soil over a certain period of time and mostly affecting soil atmosphere. According to these premises and hypotheses, we demonstrated that EN is an useful technology to measure soil microbial activity, through its correlation to specific metabolic activities occurring in soil (i.e. global and specific respiration and some enzyme activities), but also soil microbial biomass. On the basis of such evidences, we also were able to use this technology to assess the quality and health conditions of soil ecosystems in terms of metabolic indices previously identified, according to some metabolic parameters and biomass quantification of microbial populations. In other studies, we also applied EN technology, despite using a different set of sensors in the array, to analyse the atmosphere of soil ecosystems in order to assess their environmental conditions after contamination with polycyclic aromatic hydrocarbons (PAHs) (i.e. semivolatile - SVOCs - organic pollutants). In this case, EN technology resulted capable of distinguishing between contaminated and uncontaminated soils, according to the differences in a list of

  14. ASSESSMENT OF GENOTOXIC ACTIVITY OF PETROLEUM HYDROCARBON-BIOREMEDIATED SOIL

    SciTech Connect

    BRIGMON, ROBIN

    2004-10-20

    The relationship between toxicity and soil contamination must be understood to develop reliable indicators of environmental restoration for bioremediation. Two bacterial rapid bioassays: SOS chromotest and umu-test with and without metabolic activation (S-9 mixture) were used to evaluate genotoxicity of petroleum hydrocarbon-contaminated soil following bioremediation treatment. The soil was taken from an engineered biopile at the Czor Polish oil refinery. The bioremediation process in the biopile lasted 4 years, and the toxicity measurements were done after this treatment. Carcinogens detected in the soil, polyaromatic hydrocarbons (PAHs), were reduced to low concentrations (2 mg/kg dry wt) by the bioremediation process. Genotoxicity was not observed for soils tested with and without metabolic activation by a liver homogenate (S-9 mixture). However, umu-test was more sensitive than SOS-chromotest in the analysis of petroleum hydrocarbon-bioremediated soil. Analytical results of soil used in the bioassays confirmed that the bioremediation process reduced 81 percent of the petroleum hydrocarbons including PAHs. We conclude that the combined test systems employed in this study are useful tools for the genotoxic examination of remediated petroleum hydrocarbon-contaminated soil.

  15. Distribution of chromium contamination and microbial activity in soil aggregates.

    PubMed

    Tokunaga, Tetsu K; Wan, Jiamin; Hazen, Terry C; Schwartz, Egbert; Firestone, Mary K; Sutton, Stephen R; Newville, Matthew; Olson, Keith R; Lanzirotti, Antonio; Rao, William

    2003-01-01

    Biogeochemical transformations of redox-sensitive chemicals in soils can be strongly transport-controlled and localized. This was tested through experiments on chromium diffusion and reduction in soil aggregates that were exposed to chromate solutions. Reduction of soluble Cr(VI) to insoluble Cr(II) occurred only within the surface layer of aggregates with higher available organic carbon and higher microbial respiration. Sharply terminated Cr diffusion fronts develop when the reduction rate increases rapidly with depth. The final state of such aggregates consists of a Cr-contaminated exterior, and an uncontaminated core, each having different microbial community compositions and activity. Microbial activity was significantly higher in the more reducing soils, while total microbial biomass was similar in all of the soils. The small fraction of Cr(VI) remaining unreduced resides along external surfaces of aggregates, leaving it potentially available to future transport down the soil profile. Using the Thiele modulus, Cr(VI) reduction in soil aggregates is shown to be diffusion rate- and reaction rate-limited in anaerobic and aerobic aggregates, respectively. Thus, spatially resolved chemical and microbiological measurements are necessary within anaerobic soil aggregates to characterize and predict the fate of Cr contamination. Typical methods of soil sampling and analyses that average over redox gradients within aggregates can erase important biogeochemical spatial relations necessary for understanding these environments.

  16. Soil microbial activity and functional diversity changed by compaction, poultry litter and cropping in a claypan soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Changes in soil physical characteristics induced by soil compaction may alter soil microhabitats and, therefore, play a significant role in governing soil microorganisms and their activities. Laboratory incubation and field experiments were conducted in 2001 and 2002 to investigate the effects of so...

  17. Thermal soil desorption for total petroleum hydrocarbon testing on gas chromatographs

    SciTech Connect

    Mott, J.

    1995-12-31

    Testing for total petroleum hydrocarbons (TPH) is one of the most common analytical tests today. A recent development in chromatography incorporates Thermal Soil Desorption technology to enable analyses of unprepared soil samples for volatiles such as BTEX components and semi-volatiles such as diesel, PCBs, PAHs and pesticides in the same chromatogram, while in the field. A gas chromatograph is the preferred method for determining TPH because the column in a GC separates the individual hydrocarbons compounds such as benzene and toluene from each other and measures each individually. A GC analysis will determine not only the total amount of hydrocarbon, but also whether it is gasoline, diesel or another compound. TPH analysis with a GC is typically conducted with a Flame Ionization Detector (FID). Extensive field and laboratory testing has shown that incorporation of a Thermal Soil Desorber offers many benefits over traditional analytical testing methods such as Headspace, Solvent Extraction, and Purge and Trap. This paper presents the process of implementing Thermal Soil Desorption in gas chromatography, including procedures for, and advantages of faster testing and analysis times, concurrent volatile and semi-volatile analysis, minimized sample manipulation, single gas (H{sub 2}) operation, and detection to the part-per billion levels.

  18. A Petroleum Vapor Intrusion Model Involving Upward Advective Soil Gas Flow Due to Methane Generation.

    PubMed

    Yao, Yijun; Wu, Yun; Wang, Yue; Verginelli, Iason; Zeng, Tian; Suuberg, Eric M; Jiang, Lin; Wen, Yuezhong; Ma, Jie

    2015-10-06

    At petroleum vapor intrusion (PVI) sites at which there is significant methane generation, upward advective soil gas transport may be observed. To evaluate the health and explosion risks that may exist under such scenarios, a one-dimensional analytical model describing these processes is introduced in this study. This new model accounts for both advective and diffusive transport in soil gas and couples this with a piecewise first-order aerobic biodegradation model, limited by oxygen availability. The predicted results from the new model are shown to be in good agreement with the simulation results obtained from a three-dimensional numerical model. These results suggest that this analytical model is suitable for describing cases involving open ground surface beyond the foundation edge, serving as the primary oxygen source. This new analytical model indicates that the major contribution of upward advection to indoor air concentration could be limited to the increase of soil gas entry rate, since the oxygen in soil might already be depleted owing to the associated high methane source vapor concentration.

  19. Soil-gas radon analyses in the Mt. Rose and Lovelock areas, west-central Nevada

    SciTech Connect

    Ramelli, A.R.; Rigby, J.G.; LaPointe, D.D. )

    1993-04-01

    Soil-gas radon has been sampled and analyzed in two area of differing surficial geology in west-central Nevada. Elevated levels of indoor radon have been found in both area. The Mt. Rose alluvial fan complex, located just southwest of Reno, is an alluvial fan/pediment formed by flow from major drainages in the Carson Range. The surface of the Mt. Rose fan is dominated by glacial outwash deposits believed to be of Donner Lake and Tahoe age. These two units have somewhat differing lithologies and degrees of soil development. The Donner Lake outwash is dominated by volcanic clasts and typically has a thick argillic B-horizon and a moderately to strongly developed duripan. The Tahoe outwash has a mixture of volcanic and granitic clasts and typically has a thinner argillic B-horizon and no duripan. Soil-gas radon levels are generally higher in the Tahoe outwash, probably reflecting either greater emanation from granitic clasts or differences in soil gas permeability. Radon levels along Holocene faults cutting these outwash deposits are fairly typical for the study area and minor differences may be due to the faults' effects on soil gas permeability. Lovelock, about 90 miles northeast of Reno, is located within the Humboldt Sink, one of the lowest parts of the pluvial Lake Lahontan basin. Surficial geology in this area is dominated by fine-grained lacustrine deposits and overbank alluvium from the Humboldt River. During interpluvial periods, this is commonly a marshy area resulting from Humboldt River flow into the basin. Elevated radon levels are likely due to uranium accumulation in black, organic-rich clay layers.

  20. Dry deposition and soil-air gas exchange of polychlorinated biphenyls (PCBs) in an industrial area.

    PubMed

    Bozlaker, Ayse; Odabasi, Mustafa; Muezzinoglu, Aysen

    2008-12-01

    Ambient air and dry deposition, and soil samples were collected at the Aliaga industrial site in Izmir, Turkey. Atmospheric total (particle+gas) Sigma(41)-PCB concentrations were higher in summer (3370+/-1617 pg m(-3), average+SD) than in winter (1164+/-618 pg m(-3)), probably due to increased volatilization with temperature. Average particulate Sigma(41)-PCBs dry deposition fluxes were 349+/-183 and 469+/-328 ng m(-2) day(-1) in summer and winter, respectively. Overall average particulate deposition velocity was 5.5+/-3.5 cm s(-1). The spatial distribution of Sigma(41)-PCB soil concentrations (n=48) showed that the iron-steel plants, ship dismantling facilities, refinery and petrochemicals complex are the major sources in the area. Calculated air-soil exchange fluxes indicated that the contaminated soil is a secondary source to the atmosphere for lighter PCBs and as a sink for heavier ones. Comparable magnitude of gas exchange and dry particle deposition fluxes indicated that both mechanisms are equally important for PCB movement between air and soil in Aliaga.

  1. Mapping soil gas radon concentration: a comparative study of geostatistical methods.

    PubMed

    Buttafuoco, Gabriele; Tallarico, Adalisa; Falcone, Giovanni

    2007-08-01

    Understanding soil gas radon spatial variations can allow the constructor of a new house to prevent radon gas flowing from the ground. Indoor radon concentration distribution depends on many parameters and it is difficult to use its spatial variation to assess radon potential. Many scientists use to measure outdoor soil gas radon concentrations to assess the radon potential. Geostatistical methods provide us a valuable tool to study spatial structure of radon concentration and mapping. To explore the structure of soil gas radon concentration within an area in south Italy and choice a kriging algorithm, we compared the prediction performances of four different kriging algorithms: ordinary kriging, lognormal kriging, ordinary multi-Gaussian kriging, and ordinary indicator cokriging. Their results were compared using an independent validation data set. The comparison of predictions was based on three measures of accuracy: (1) the mean absolute error, (2) the mean-squared error of prediction; (3) the mean relative error, and a measure of effectiveness: the goodness-of-prediction estimate. The results obtained in this case study showed that the multi-Gaussian kriging was the most accurate approach among those considered. Comparing radon anomalies with lithology and fault locations, no evidence of a strict correlation between type of outcropping terrain and radon anomalies was found, except in the western sector where there were granitic and gneissic terrain. Moreover, there was a clear correlation between radon anomalies and fault systems.

  2. Active tectonic features and structural dynamics of the summit area of Mt. Etna (Italy) revealed by soil CO2 and soil temperature surveying

    NASA Astrophysics Data System (ADS)

    Giammanco, Salvatore; Melián, Gladys; Neri, Marco; Hernández, Pedro A.; Sortino, Francesco; Barrancos, José; López, Manuela; Pecoraino, Giovannella; Perez, Nemesio M.

    2016-02-01

    This work presents the results of an extensive geochemical survey aimed at measuring soil CO2 effluxes and soil temperatures over a large portion of Mt. Etna's summit area, coupled with an updated structural survey of the same area. The main goals of this study were i) to find concealed or hidden volcano-tectonic structures in the studied area by detecting anomalous soil gas emissions, ii) to investigate the origin of the emitted gas and the mechanism of gas and heat transport to the surface, iii) to produce a structural model based both on the surface geology and on the soil gas data and, lastly, iv) to contribute to the assessment of hazard from slope failure and crater collapses at Mt. Etna. The results revealed many concealed structural lines that followed the major directions of structural weakness in the summit area of Mt. Etna, mostly due to a combined action of gravitational spreading of the volcano and magma intrusions. Both recent and old volcano-tectonic lines were found to act as pathways for the leakage of magmatic gases to the surface. An important role in driving magmatic gases to the surface is also played by fracturing and faulting due to caldera-forming collapses and smaller crater collapses. Correlation between soil CO2 emissions and soil temperature allowed discriminating areas of active shallow hydrothermal circulation along deep fractures (characterized by high values of both parameters, but mostly soil temperature) from those affected by undeveloped fractures that did not reach the surface (characterized by high CO2 emissions at low temperature). The former corresponded to weak zones of the volcano edifice that were frequently site of past eruptions, indicating that those areas keep a high potential for future opening of eruptive fissures. The latter were likely related to sites where new eruptive fissures may open in the near future due to backward propagation of extensional tectonic stress.

  3. In vitro determination of oxidation of atmospheric tritium gas in vegetation and soil in Ibaraki and Gifu, Japan.

    PubMed

    Ichimasa, M; Suzuki, M; Obayashi, H; Sakuma, Y; Ichimasa, Y

    1999-09-01

    To quantify the rate of oxidation of tritium gas (referred to as HT) to tritiated water in the environment, various woody and herbaceous plant leaves and roots, mosses and lichens taken from a forest and fields in Ibaraki prefecture, and a forest in Toki, Gifu prefecture, were investigated as to their ability to oxidize atmospheric HT in in vitro experiments. The HT oxidation activity in vegetation was compared with that in the surrounding surface soil (0-5 cm in depth). The rate of oxidation of HT in woody plant leaves including pine needles was extremely low, only about 1/10000-1/1000 that in the surface soil, as well as in herbaceous plant leaves with some exceptions (Phalaris arundinacea and Vaccinium smallii), whereas the rate in mosses and lichens was 50-500 times that in pine needles. The HT oxidation activity in roots of several plants including Phalaris arundinacea, Pieris japonica and Lespedeza homoloba was quite high and comparable to that in the surrounding surface soil. These results suggest that mosses, lichens and the leaves or roots of particular plants with high HT oxidation activity can be used to monitor the accidental release of HT into the environment.

  4. Toxicological effects of dimethomorph on soil enzymatic activity and soil earthworm (Eisenia fetida).

    PubMed

    Wang, Caixia; Zhang, Qingming; Wang, Feifei; Liang, Wenxing

    2017-02-01

    The objective of this study was to evaluate the toxicity of the fungicide dimethomorph to soil microbial activity and the earthworm Eisenia fetida. Multiple biomarkers, namely, four soil enzymes (urease, dehydrogenase, invertase, and acid phosphatase), four earthworm biochemical indices (dismutase, catalase, cellulase, and malondialdehyde), and the transcriptional levels of both target genes (dismutase and catalase) were measured at 1, 10, and 100 mg kg(-1) after 1, 7, 21, and 28 days. The degradation rate of dimethomorph in soil was also determined, and the results indicated that most parameters did not differ from the controls at 1 and 10 mg kg(-1) dimethomorph by the last exposure time (28 d). However, high concentrations (100 mg kg(-1)) of dimethomorph had varying effects on soil enzymatic activity and earthworms. These effects gradually decreased with prolonged exposure times. Positive correlations (R(2) > 0.57) between the target gene expression levels and antioxidant enzyme activities were observed in this study. We also found that earthworms have improved soil microbial activity and accelerated the degradation of dimethomorph. Overall, higher concentrations of dimethomorph might pose an ecological hazard to soil environments in the short term.

  5. The role of soil air composition for noble gas tracer applications in tropical groundwater

    NASA Astrophysics Data System (ADS)

    Mayer, Simon; Jenner, Florian; Aeschbach, Werner; Weissbach, Therese; Peregovich, Bernhard; Machado, Carlos

    2016-04-01

    Dissolved noble gases (NGs) in groundwater provide a well-established tool for paleo temperature reconstruction. However, reliable noble gas temperature (NGT) determination needs appropriate assumptions or rather an exact knowledge of soil air composition. Deviations of soil air NG partial pressures from atmospheric values have already been found in mid latitudes during summer time as a consequence of subsurface oxygen depletion. This effect depends on ambient temperature and humidity and is thus expected to be especially strong in humid tropical soils, which was not investigated so far. We therefore studied NGs in soil air and shallow groundwater near Santarém (Pará, Brazil) at the end of the rainy and dry seasons, respectively. Soil air data confirms a correlation between NG partial pressures, the sum value of O2+CO2 and soil moisture contents. During the rainy season, we find significant NG enhancements in soil air by up to 7% with respect to the atmosphere. This is twice as much as observed during the dry season. Groundwater samples show neon excess values between 15% and 120%. Nearly all wells show no seasonal variations of excess air, even though the local river level seasonally fluctuates by about 8 m. Assuming atmospheric NG contents in soil air, fitted NGTs underestimate the measured groundwater temperature by about 1-2° C. However, including enhanced soil air NG contents as observed during the rainy season, resulting NGTs are in good agreement with local groundwater temperatures. Our presented data allows for a better understanding of subsurface NG variations. This is essential with regard to NG tracer applications in humid tropical areas, for which reliable paleoclimate data is of major importance for modern climate research.

  6. Methanotrophic activity and bacterial diversity in volcanic-geothermal soils at Pantelleria island (Italy)

    NASA Astrophysics Data System (ADS)

    Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.

    2014-04-01

    Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic/geothermal soils are source of methane, but also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria island (Italy), Favara Grande, whose total methane emission was previously estimated in about 2.5 t a-1. Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values up to 950 ng g-1 dry soil h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile and the maximum methane consumption was measured in the top-soil layer but values > 100 ng g-1 h-1 were maintained up to a depth of 15 cm. The highest consumption rate was measured at 37 °C, but a still recognizable consumption at 80 °C (> 20 ng g-1 h-1) was recorded. In order to estimate the bacterial diversity, total soil DNA was extracted from Favara Grande and analysed using a Temporal Temperature Gradient gel Electrophoresis (TTGE) analysis of the amplified bacterial 16S rRNA gene. The three soil samples were probed by PCR using standard proteobacterial primers and newly designed verrucomicrobial primers targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected in sites FAV2 and FAV3, but not in FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site FAV2 pointed out a high diversity of gammaproteobacterial methanotrophs distantly related to Methylococcus/Methylothermus genera and the presence of the newly discovered acido-thermophilic methanotrophs

  7. Studies of soil and ecohydrological processes in oil-gas production regions.

    NASA Astrophysics Data System (ADS)

    Khodyreva, E. Ya.; Khodyrev, Yu. P.

    2009-04-01

    For a better understanding and describing of the functional interactions between processes in soil and drinking, underground and stratum waters in oil-gas production regions we used laboratory and field monitoring methods of studies. The control of ecological situation dynamics in oil-gas production regions proposes a presence of primary data about parameter-indicators, which characterize a state of the object under investigation. One of these parameters is the concentration of heavy metal salts in drinking and stratum waters. Isolation of some compounds, which are extracted as impurities of oil and water during recovery of hydrocarbons from productive horizons, would enhance profitableness of recovery. Because accompanying impurities are a mixture of different salts and complexes, the methods of multielement analysis give the most objective evaluation of total content of some elements by search and prospecting. The developed method of laser mass-spectrometric analysis of oil and drinking, underground and industrial waters allows to investigate the samples on all elements of the periodical system simultaneously with limit sensitivity 0.1 mkg/l. The preparation of the oil and water probes was carried out by sublimation of highly volatile fractions in vacuum at 100 0C. The samples of drinking and underground waters, oils and industrial waters from wells of oil field Romashkin (Tatarstan) were chosen as the object for the research. In respect to possible metal extraction scandium is of most interest in inspected area because it's very high cost and availability of water-soluble pattern, most probably chloride. Its concentration in one well was 1 mg/l in water and 0.01 mg/l in oil. According to the received data of laser mass-spectrometric analysis, industrial waters on the activity investigated territory joint-stock company "Tatneft" contain 220-330 kg / ton of salts of metals that does by their potential source of alternative raw material for the chemical industry

  8. Longevity of terrestrial Carbon sinks: effects of soil degradation on greenhouse gas emissions

    NASA Astrophysics Data System (ADS)

    Kuhn, Nikolaus J.; Berger, Samuel; Kuonen, Samuel

    2013-04-01

    productivity associated with erosion. Areas with high erosion rates and already erosion-induced damages to soil productivity were considered to be closing or closed landscape carbon sinks. The final global assessment indicates that severe soil degradation in Africa, the Americas and Asia carries the risk of closing terrestrial Carbon sinks that currently contribute to an unintended mitigation of greenhouse gas emissions.

  9. Active Layer Soil Carbon and Nutrient Mineralization, Barrow, Alaska, 2012

    DOE Data Explorer

    Stan D. Wullschleger; Holly M. Vander Stel; Colleen Iversen; Victoria L. Sloan; Richard J. Norby; Mallory P. Ladd; Jason K. Keller; Ariane Jong; Joanne Childs; Deanne J. Brice

    2015-10-29

    This data set consists of bulk soil characteristics as well as carbon and nutrient mineralization rates of active layer soils manually collected from the field in August, 2012, frozen, and then thawed and incubated across a range of temperatures in the laboratory for 28 day periods in 2013-2015. The soils were collected from four replicate polygons in each of the four Areas (A, B, C, and D) of Intensive Site 1 at the Next-Generation Ecosystem Experiments (NGEE) Arctic site near Barrow, Alaska. Soil samples were coincident with the established Vegetation Plots that are located in center, edge, and trough microtopography in each polygon. Data included are 1) bulk soil characteristics including carbon, nitrogen, gravimetric water content, bulk density, and pH in 5-cm depth increments and also by soil horizon, 2) carbon, nitrogen, and phosphorus mineralization rates for soil horizons incubated aerobically (and in one case both aerobically and anaerobically) for 28 days at temperatures that included 2, 4, 8, and 12 degrees C. Additional soil and incubation data are forthcoming. They will be available when published as part of another paper that includes additional replicate analyses.

  10. Economic Potential of Greenhouse Gas Emission Reductions: Comparative Role for Soil Sequestration in Agriculture and Forestry

    SciTech Connect

    Mccarl, Bruce A.; Schneider, Uwe; Murray, Brian; Williams, Jimmy; Sands, Ronald D.

    2001-05-14

    This paper examines the relative contribution of agricultural and forestry activities in an emission reduction program, focusing in part on the relative desirability of sequestration in forests and agricultural soils. The analysis considers the effects of competition for land and other resources between agricultural activities, forestry activities and traditional production. In addition, the paper examines the influence of saturation and volatility.

  11. Bioremediation of hydrocarbon degradation in a petroleum-contaminated soil and microbial population and activity determination.

    PubMed

    Wu, Manli; Li, Wei; Dick, Warren A; Ye, Xiqiong; Chen, Kaili; Kost, David; Chen, Liming

    2017-02-01

    Bioremediation of hydrocarbon degradation in petroleum-polluted soil is carried out by various microorganisms. However, little information is available for the relationships between hydrocarbon degradation rates in petroleum-contaminated soil and microbial population and activity in laboratory assay. In a microcosm study, degradation rate and efficiency of total petroleum hydrocarbons (TPH), alkanes, and polycyclic aromatic hydrocarbons (PAH) in a petroleum-contaminated soil were determined using an infrared photometer oil content analyzer and a gas chromatography mass spectrometry (GC-MS). Also, the populations of TPH, alkane, and PAH degraders were enumerated by a modified most probable number (MPN) procedure, and the hydrocarbon degrading activities of these degraders were determined by the Biolog (MT2) MicroPlates assay. Results showed linear correlations between the TPH and alkane degradation rates and the population and activity increases of TPH and alkane degraders, but no correlation was observed between the PAH degradation rates and the PAH population and activity increases. Petroleum hydrocarbon degrading microbial population measured by MPN was significantly correlated with metabolic activity in the Biolog assay. The results suggest that the MPN procedure and the Biolog assay are efficient methods for assessing the rates of TPH and alkane, but not PAH, bioremediation in oil-contaminated soil in laboratory.

  12. Ecotoxicological assessment of soils of former manufactured gas plant sites: Bioremediation potential and pollutant mobility

    SciTech Connect

    Haeseler, F.; Blanchet, D.; Druelle, V.; Werner, P.; Vandecasteele, J.P.

    1999-12-15

    Analytically well-characterized soils from four different former manufactured gas plants (MGP) sites contaminated by coal tars were used in tests of extensive biodegradation of polycyclic aromatic hydrocarbons (PAHs) in stirred reactors. In all cases, the extent of biodegradation was limited to 80--100% for 2- and 3-ring PAHs, 40--70% for 4-ring PAHs, and below 20% for 5- and 6-ring PAHs. The capacities to transfer pollutants to water were compared for leachates from soils that had or had not undergone biological treatment. Leachate analysis involved determination of PAHs and bacterial tests of acute toxicity (Microtox) and genotoxicity (SOS Chromotest). For some untreated soils, PAH leaching was observed, and positive responses to the Microtox test were well correlated to the concentrations of naphthalene and phenanthrene. Biologically treated soils had lost all capacities for leaching as concluded from PAH determinations and responses to the Microtox test. All soil leachates were devoid of genotoxic effect, in accordance with the low concentrations observed of mutagenic PAHs. The results of this risk-based approach for assessment of MGP soils showed that pollutants remaining after biological treatment were unavailable for further biodegradation and that the extent of leaching had been reduced to the level that it did not represent a significant threat to groundwater.

  13. The NASA Soil Moisture Active Passive (SMAP) Mission: Overview

    NASA Technical Reports Server (NTRS)

    O'Neill, Peggy; Entekhabi, Dara; Njoku, Eni; Kellogg, Kent

    2011-01-01

    The Soil Moisture Active Passive (SMAP) mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council?s Decadal Survey [1]. Its mission design consists of L-band radiometer and radar instruments sharing a rotating 6-m mesh reflector antenna to provide high-resolution and high-accuracy global maps of soil moisture and freeze/thaw state every 2-3 days. The combined active/passive microwave soil moisture product will have a spatial resolution of 10 km and a mean latency of 24 hours. In addition, the SMAP surface observations will be combined with advanced modeling and data assimilation to provide deeper root zone soil moisture and net ecosystem exchange of carbon. SMAP is expected to launch in the late 2014 - early 2015 time frame.

  14. Soil-Gas Identification of Environmental Factors Affecting CO2 Concentrations Beneath a Playa Wetland: Implications for Soil-Gas Monitoring at Carbon Storage Sites

    NASA Astrophysics Data System (ADS)

    Romanak, K.; Bennett, P.

    2009-12-01

    Strategies for identifying and interpreting the effects of environmental factors on near-surface CO2 concentrations are essential to developing accurate monitoring protocols at carbon storage sites. Based on the results of a three-year study of a natural analogue we present, 1) a method for using soil-gas to identify near-surface CO2 cycling, and 2) a framework for developing monitoring protocols and site evaluation for near-surface monitoring. Near-surface CO2 production, consumption, and re-distribution was observed in the vadose-zone of a highly CO2-reactive playa wetland in the Texas High Plains. Atmospheric conditions, organic and inorganic soil carbon, subsurface pressure, water flux, and surface and groundwater chemistry were compared to real-time background measurements of CO2, CH4, O2+Ar, and N2 from depths up to 45 feet. Carbon isotopes and spatially and temporally variable concentrations of CO2 ≤ 17%, CH4 ≤ 2%, and O2 from 21-0% indicate CO2 and CH4 are produced by microbes. Molar gas ratios of O2 and CO2 distinguish between oxidation of organic matter (CH2O + O2 → CO2 + H2O), CH4 oxidation (CH4 + 2O2 → CO2 + 2H2O), and potentially acetate fermentation (CH3COOH → CH4 + CO2). O2 consumption and distribution is regulated by water flux that supplies dissolved organics to microbes at depth and regulates oxygen supply by blocking vertical permeability and atmospheric gas exchange. A surface flux experiment indicates that when playa floors are dry, subsurface wetting fronts from rain events or previous ponding periods block vertical permeability resulting in surface flux measurements that do not represent subsurface conditions. Samples with CO2+O2 < 21% and N2 > 78% identify dissolution of CO2 and carbonate minerals into recharging groundwater resulting in loss of pore pressure and chemically-induced advection of atmosphere into pores. Inverse geochemical reaction modeling (PHREEQC) of playa surface water and perched groundwater in high PCO2 zones

  15. [Effects of nitrogen application on soil greenhouse gas fluxes in Eucalyptus plantations with different soil organic carbon content].

    PubMed

    Li, Rui-Da; Zhang, Kai; Su, Dan; Lu, Fei; Wan, Wu-Xing; Wang, Xiao-Ke; Zheng, Hua

    2014-10-01

    The effects of nitrogen fertilization or nitrogen deposition on soil greenhouse gases fluxes has been well studied, while little has been piloted about the effects of nitrogen application on soil greenhouse gas fluxes and its discrepancy with different soil organic carbon content. In our study, we conducted field control experiment in a young Eucalyptus plantation in Southeast China. We compared the effects of 4 levels of nitrogen fertilization (Control: 0 kg · hm(-2); Low N: 84.2 kg · hm(-2); Medium N: 166.8 kg · hm(-2); High N: 333.7 kg · hm(-2)) on soil GHGs fluxes from 2 sites (LC and HC) with significantly different soil organic carbon (SOC) content (P < 0.05). The results showed: (1) Fertilization had significant priming effect on CO2 and N2O emission fluxes. One month after fertilization, both CO2 and N2O had the flux peak and decreased gradually, and the difference among the treatments disappeared at the end of the growing season. However, fertilization had no significant effect on CH4 oxidation between the 2 sites. (2) Fertilization and SOC were two crucial factors that had significant effects on CO2 and N2O emission. Fertilization had a significant positive effect on CO2 and N2O emission fluxes (P < 0.001). CH4 oxidation rates decreased with the increasing N addition, but there was no statistical difference (P > 0.05). The CO2 and N2O emission fluxes were significantly higher in HC than those in LC (P < 0.01). (3) Fertilization and SOC had great interactive effect on CO2 and N2O emission (P < 0.05). Compared with fluxes in LC, the fluxes in HC were much more sensitive to N input: low N could remarkably stimulate the CO2 and N2O emission. In conclusion, the effects of nitrogen fertilization on soil GHGs fluxes were not only in connection with the intensify of nitrogen, but also closely tied to the SOC content. When we assess the effects of nitrogen on soil GHGs fluxes, the difference induced by SOC should not be ignored.

  16. Laser Absorption spectrometer instrument for tomographic 2D-measurement of climate gas emission from soils

    NASA Astrophysics Data System (ADS)

    Seidel, Anne; Wagner, Steven; Dreizler, Andreas; Ebert, Volker

    2014-05-01

    One of the most intricate effects in climate modelling is the role of permafrost thawing during the global warming process. Soil that has formerly never totally lost its ice cover now emits climate gases due to melting processes[1]. For a better prediction of climate development and possible feedback mechanisms, insights into physical procedures (like e.g. gas emission from underground reservoirs) are required[2]. Therefore, a long-term quantification of greenhouse gas concentrations (and further on fluxes) is necessary and the related structures that are responsible for emission need to be identified. In particular the spatial heterogeneity of soils caused by soil internal structures (e.g. soil composition changes or surface cracks) or by surface modifications (e.g. by plant growth) generate considerable complexities and difficulties for local measurements, for example with soil chambers. For such situations, which often cannot be avoided, a spatially resolved 2D-measurement to identify and quantify the gas emission from the structured soil would be needed, to better understand the influence of the soil sub-structures on the emission behavior. Thus we designed a spatially scanning laser absorption spectrometer setup to determine a 2D-gas concentration map in the soil-air boundary layer. The setup is designed to cover the surfaces in the range of square meters in a horizontal plane above the soil to be investigated. Existing field instruments for gas concentration or flux measurements are based on point-wise measurements, so structure identification is very tedious or even impossible. For this reason, we have developed a tomographic in-situ instrument based on TDLAS ('tunable diode laser absorption spectroscopy') that delivers absolute gas concentration distributions of areas with 0.8m × 0.8m size, without any need for reference measurements with a calibration gas. It is a simple and robust device based on a combination of scanning mirrors and reflecting foils, so

  17. Impact of nitrogen fertilization on soil-Atmosphere greenhouse gas exchanges in eucalypt plantations with different soil characteristics in southern China.

    PubMed

    Zhang, Kai; Zheng, Hua; Chen, Falin; Li, Ruida; Yang, Miao; Ouyang, Zhiyun; Lan, Jun; Xiang, Xuewu

    2017-01-01

    Nitrogen (N) fertilization is necessary to sustain productivity in eucalypt plantations, but it can increase the risk of greenhouse gas emissions. However, the response of soil greenhouse gas emissions to N fertilization might be influenced by soil characteristics, which is of great significance for accurately assessing greenhouse gas budgets and scientific fertilization in plantations. We conducted a two-year N fertilization experiment (control [CK], low N [LN], middle N [MN] and high N [HN] fertilization) in two eucalypt plantations with different soil characteristics (higher and lower soil organic carbon sites [HSOC and LSOC]) in Guangxi, China, and assessed soil-atmosphere greenhouse gas exchanges. The annual mean fluxes of soil CO2, CH4, and N2O were separately 153-266 mg m-2 h-1, -55 --40 μg m-2 h-1, and 11-95 μg m-2 h-1, with CO2 and N2O emissions showing significant seasonal variations. N fertilization significantly increased soil CO2 and N2O emissions and decreased CH4 uptake at both sites. There were significant interactions of N fertilization and SOC level on soil CO2 and N2O emissions. At the LSOC site, the annual mean flux of soil CO2 emission was only significantly higher than the CK treatment in the HN treatment, but, at the HSOC site, the annual mean flux of soil CO2 emission was significantly higher for both the LN (or MN) and HN treatments in comparison to the CK treatment. Under the CK and LN treatments, the annual mean flux of N2O emission was not significantly different between HSOC and LSOC sites, but under the HN treatment, it was significantly higher in the HSOC site than in the LSOC site. Correlation analysis showed that changes in soil CO2 and N2O emissions were significantly related to soil dissolved organic carbon, ammonia, nitrate and pH. Our results suggested significant interactions of N fertilization and soil characteristics existed in soil-atmosphere greenhouse gas exchanges, which should be considered in assessing greenhouse gas

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

    PubMed

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

    2011-12-01

    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.

  19. Correlation of lineaments with soil gas anomalies in the Atlantic Coastal Plain

    SciTech Connect

    Wyatt, D.E. |; Richers, D.

    1994-08-23

    Results from a soil gas survey, performed in the Atlantic Coastal Plain and centered on the US Department of Energy Savannah River Site discovered areas of anomalous (greater than one standard deviation above the mean) methane, ethane, propane, hydrogen and carbon dioxide. A lineament study was performed to investigate whether these anomalies may be associated with fractures or faults and therefore be sourced in basement rocks. The lineament study used a regional aeromagnetic map, various scale topographic maps and a Landsat image. The results of the study suggest the following: (1) correcting for barometric pumping effects, the soil gas anomalies have a strong coincidence with lineations, (2) comparing linear features discernible on a variety of sources mapped at different scales allows for a combined data set to be formed that may define a lineation zone, and (3) linear trends compare favorably with suspected structural trends for the coastal plain.

  20. A comparison of three bacterial strains for the remediation of town gas soils

    SciTech Connect

    Sauer, N.E.; Akkineni, D.K.; Cutright, T.J.

    1995-12-31

    The contamination of soils from polycyclic aromatic hydrocarbons (PAHs) is widespread. Although PAH contamination still occurs from current industrial processes, accidental spills, and leaking underground storage tanks, the main source of contamination is from abandoned town gas sites. To date there is a conservative estimate of 2500 town gas sites that require remediation. The most cost effective in-situ treatment for these sites is that of bioremediation. Experiments were conducted to compare the efficiencies of three bacterial strains for the remediation of an industrially PAH contaminated soil. Specifically, the efficiencies of Achromobacter sp., Mycobacterium sp., and Nocardia paraffinae were investigated. This paper will address the chemical specificity of each bacterial strains for the PAHs present.

  1. Climate effect on soil enzyme activities and dissolved organic carbon in mountain calcareous soils: a soil-transplant experiment

    NASA Astrophysics Data System (ADS)

    Puissant, Jérémy; Cécillon, Lauric; Mills, Robert T. E.; Gavazov, Konstantin; Robroek, Bjorn J. M.; Spiegelberger, Thomas; Buttler, Alexandre; Brun, Jean-Jacques

    2013-04-01

    Mountain soils store huge amounts of carbon as soil organic matter (SOM) which may be highly vulnerable to the strong climate changes that mountain areas currently experience worldwide. Climate modifications are expected to impact microbial activity which could change the rate of SOM decomposition/accumulation, thereby questioning the net C source/sink character of mountain soils. To simulate future climate change expected in the 21st century in the calcareous pre-Alps, 15 blocks (30 cm deep) of undisturbed soil were taken from a mountain pasture located at 1400 m a.s.l. (Marchairuz, Jura, Switzerland) and transplanted into lysimeters at the same site (control) and at two other sites located at 1000 m a.s.l. and 600 m a.s.l. (5 replicates per site). This transplantation experiment which started in 2009 simulates a climate warming with a temperature increase of 4° C and a decreased humidity of 40 % at the lowest site. In this study, we used soil extracellular enzyme activities (EEA) as functional indicators of SOM decomposition to evaluate the effect of climate change on microbial activity and SOM dynamics along the seasons. Dissolved organic carbon (DOC) was also measured to quantify the assimilable carbon for microorganism. In autumn 2012, a first sampling step out of four (winter, spring and summer 2013) has been realized. We extracted 15 cm deep soil cores from each transplant (x15) and measured (i) DOC and (ii) the activities of nine different enzymes. Enzymes were chosen to represent the degradation of the most common classes of biogeochemical compounds in SOM. β-glucosidase, β-D-cellubiosidase, β-Xylosidase, N-acetyl-β-glucosaminidase, leucine aminopeptidase, lipase, phenoloxidase respectively represented the degradation of sugar, cellulose, hemicellulose, chitin, protein, lipid and lignin. Moreover, the fluorescein diacetate (FDA) hydrolysis was used to provide an estimate of global microbial activity and phosphatase was used to estimate phosphorus

  2. Comparison of soil applied flue gas desulfurization (FGD) and agricultural gypsum on soil physical properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gypsum can come from different sources. Agricultural gypsum is typically mined and used to supply calcium to crops. Flue gas desulfurization (FGD) gypsum is a by-product of coal power plants. Although their chemical formulas are the same, different trace elements and materials are present in them....

  3. Gas/solid particulate phthalic esters (PAEs) in Masson pine (Pinus massoniana L.) needles and rhizosphere surface soils.

    PubMed

    Wang, Wen-xin; Fan, Chinbay Q

    2014-07-15

    Phthalic acid esters (PAEs) are used in many branches of industry and are produced in huge amounts throughout the world. An investigation on particulate- and gas-phase distribution of PAEs has been conducted between January 2011 and December 2012 in Nanjing (China). Masson pine (Pinus massoniana L.) needles and rhizosphere surface soils were sampled from urban to suburban/remote sites, to investigate the pine needle/soil distribution of PAEs. The results showed that the average total PAE concentration (gas+particle) was 97.0ngm(-3). The six PAE congeners considered predominantly existed in the gas phase and the average contribution of gas phase to total PAEs ranged from 75.0% to 89.1%. The PAE concentrations in rhizosphere soils and pine needles were positively correlated with their particulate- and gas-phase concentrations, respectively, which suggested that surface soils accumulated PAEs mainly through gravity deposition of particles and pine needle stomata absorbed PAEs mainly from the gas phase. The gas/particle partitioning (KP) and soil-pine needle ratio (Rs/n) were determined. Experimentally determined KP values correlated well with the subcooled liquid vapor pressures (PL). A set of interesting relationships of logRs/n-logKP-logPL was employed to explain the experimental findings of PAEs deposition to surface soils and to needles. This data set offered a unique perspective into the influence that Rs/n played in KP and correlated with PL.

  4. Multiresidue analysis of pesticides in soil by gas chromatography with nitrogen-phosphorus detection and gas chromatography mass spectrometry.

    PubMed

    Fenoll, José; Hellín, Pilar; Marín, Cristóbal; Martínez, Carmen M; Flores, Pilar

    2005-10-05

    A rapid multiresidue method for the simultaneous determination of 25 fungicides and insecticides in soil was developed. Soil samples are extracted by sonication with a water-acetonitrile mixture, and the pesticides are partitioned into dichloromethane. Final determination was made by gas chromatography (GC) with nitrogen-phosphorus detection (NPD). Confirmation analysis of pesticides was carried out by GC-MS in the selected ion monitoring (SIM) mode. The identification of compounds was based on retention time and on comparison of the primary and secondary ions. The average recovery by the GC-NPD method obtained for these compounds varied from 68.5% to 112.1% with a relative standard deviation between 1.8% and 6.2%. The GC-NPD method presents good linearity over the range assayed 50-2000 microg/L, and the detection limit for the pesticides studied varied from 0.1 to 10.4 microg/kg. The proposed method was used to determine pesticide levels in soil samples from experimental greenhouse pepper cultivation.

  5. Biofuel intercropping effects on soil carbon and microbial activity.

    PubMed

    Strickland, Michael S; Leggett, Zakiya H; Sucre, Eric B; Bradford, Mark A

    2015-01-01

    Biofuels will help meet rising demands for energy and, ideally, limit climate change associated with carbon losses from the biosphere to atmosphere. Biofuel management must therefore maximize energy production and maintain ecosystem carbon stocks. Increasingly, there is interest in intercropping biofuels with other crops, partly because biofuel production on arable land might reduce availability and increase the price of food. One intercropping approach involves growing biofuel grasses in forest plantations. Grasses differ from trees in both their organic inputs to soils and microbial associations. These differences are associated with losses of soil carbon when grasses become abundant in forests. We investigated how intercropping switchgrass (Panicum virgalum), a major candidate for cellulosic biomass production, in loblolly pine (Pinus taeda) plantations affects soil carbon, nitrogen, and microbial dynamics. Our design involved four treatments: two pine management regimes where harvest residues (i.e., biomass) were left in place or removed, and two switchgrass regimes where the grass was grown with pine under the same two biomass scenarios (left or removed). Soil variables were measured in four 1-ha replicate plots in the first and second year following switchgrass planting. Under switchgrass intercropping, pools of mineralizable and particulate organic matter carbon were 42% and 33% lower, respectively. These declines translated into a 21% decrease in total soil carbon in the upper 15 cm of the soil profile, during early stand development. The switchgrass effect, however, was isolated to the interbed region where switchgrass is planted. In these regions, switchgrass-induced reductions in soil carbon pools with 29%, 43%, and 24% declines in mineralizable, particulate, and total soil carbon, respectively. Our results support the idea that grass inputs to forests can prime the activity of soil organic carbon degrading microbes, leading to net reductions in stocks

  6. Short-term temporal variations of soil gas radon concentration and comparison of measurement techniques.

    PubMed

    Neznal, Martin; Matolín, Milan; Just, Günther; Turek, Karel

    2004-01-01

    Short-term temporal variations of soil gas radon concentration have been studied using different measuring techniques--instantaneous methods (grab sampling) using Lucas cells, continuous monitors, and integral nuclear track-etch detectors. A relatively low variability appeared during a 72-h follow-up. Different temporal changes were observed by using different methods. A substantial part of these changes was probably caused by fluctuations and errors connected with measuring methods themselves and did not reflect real variations of the measured parameter.

  7. Land-Use Change, Soil Process and Trace Gas Fluxes in the Brazilian Amazon Basin

    NASA Technical Reports Server (NTRS)

    Melillo, Jerry M.; Steudler, Paul A.

    1997-01-01

    We measured changes in key soil processes and the fluxes of CO2, CH4 and N2O associated with the conversion of tropical rainforest to pasture in Rondonia, a state in the southwest Amazon that has experienced rapid deforestation, primarily for cattle ranching, since the late 1970s. These measurements provide a comprehensive quantitative picture of the nature of surface soil element stocks, C and nutrient dynamics, and trace gas fluxes between soils and the atmosphere during the entire sequence of land-use change from the initial cutting and burning of native forest, through planting and establishment of pasture grass and ending with very old continuously-pastured land. All of our work is done in cooperation with Brazilian scientists at the Centro de Energia Nuclear na Agricultura (CENA) through an extant official bi-lateral agreement between the Marine Biological Laboratory and the University of Sao Paulo, CENA's parent institution.

  8. Process and apparatus for obtaining samples of liquid and gas from soil

    DOEpatents

    Rossabi, Joseph; May, Christopher P.; Pemberton, Bradley E.; Shinn, Jim; Sprague, Keith

    1999-01-01

    An apparatus and process for obtaining samples of liquid and gas from subsurface soil is provided having filter zone adjacent an external expander ring. The expander ring creates a void within the soil substrate which encourages the accumulation of soil-borne fluids. The fluids migrate along a pressure gradient through a plurality of filters before entering a first chamber. A one-way valve regulates the flow of fluid into a second chamber in further communication with a collection tube through which samples are collected at the surface. A second one-way valve having a reverse flow provides additional communication between the chambers for the pressurized cleaning and back-flushing of the apparatus.

  9. Process and apparatus for obtaining samples of liquid and gas from soil

    DOEpatents

    Rossabi, J.; May, C.P.; Pemberton, B.E.; Shinn, J.; Sprague, K.

    1999-03-30

    An apparatus and process for obtaining samples of liquid and gas from subsurface soil is provided having filter zone adjacent an external expander ring. The expander ring creates a void within the soil substrate which encourages the accumulation of soil-borne fluids. The fluids migrate along a pressure gradient through a plurality of filters before entering a first chamber. A one-way valve regulates the flow of fluid into a second chamber in further communication with a collection tube through which samples are collected at the surface. A second one-way valve having a reverse flow provides additional communication between the chambers for the pressurized cleaning and back-flushing of the apparatus. 8 figs.

  10. Greenhouse gas emissions and global warming potential of reclaimed forest and grassland soils.

    PubMed

    Shrestha, Raj K; Lal, Rattan; Penrose, Chris

    2009-01-01

    Although greenhouse gas (GHG) emissions from soils are important, reclaimed mine soil (RMS) ecosystems are not widely assessed. Postreclamation land uses (forest, hay, and pasture) were investigated to: (i) monitor the magnitude of GHG fluxes, (ii) estimate their global warming potential (GWP), (iii) identify the relationship between GHG fluxes and soil properties, and (iv) develop a soil quality index by principal component analysis (PCA). The GHG fluxes were measured for 1 yr cycle and simultaneous measurements were also made for soil moisture and temperature. The RMS-forest, -hay, and -pasture land uses had weighted average fluxes of 1.16, 1.66, and 3.06 g CO(2)-C m(-2) d(-1); 0.33, 0.48 and 1.1 mg CH(4)-C m(-2) d(-1); and 0.33, 0.70, and 1.06 mg N(2)O-N m(-2) d(-1), respectively. The CO(2), CH(4), and N(2)O fluxes were consistently high in the RMS-pasture and low in the RMS-forest. The GWP (CO(2)-C equivalent) of the postreclamation land uses was in the order of RMS-forest (4.5 Mg ha(-1) yr(-1)) = RMS-hay (6.8 Mg ha(-1) yr(-1)) < RMS-pasture (12.3 Mg ha(-1) yr(-1)). The PCA showed that four PCs with eigenvalues > 1 explained 88.8% of the total variance in the soil properties. The first PC is mostly characterized by soil physical properties and the second by chemical properties. Soil and air temperatures were positively correlated with CO(2), CH(4), and N(2)O fluxes. The results suggest that GWP from RMS can be minimized by establishing forest land use.

  11. Acid-activated biochar increased sulfamethazine retention in soils.

    PubMed

    Vithanage, Meththika; Rajapaksha, Anushka Upamali; Zhang, Ming; Thiele-Bruhn, Sören; Lee, Sang Soo; Ok, Yong Sik

    2015-02-01

    Sulfamethazine (SMZ) is an ionizable and highly mobile antibiotic which is frequently found in soil and water environments. We investigated the sorption of SMZ onto soils amended with biochars (BCs) at varying pH and contact time. Invasive plants were pyrolyzed at 700 °C and were further activated with 30 % sulfuric (SBBC) and oxalic (OBBC) acids. The sorption rate of SMZ onto SBBC and OBBC was pronouncedly pH dependent and was decreased significantly when the values of soil pH increased from 3 to 5. Modeled effective sorption coefficients (K D,eff) values indicated excellent sorption on SBBC-treated loamy sand and sandy loam soils for 229 and 183 L/kg, respectively. On the other hand, the low sorption values were determined for OBBC- and BBC700-treated loamy sand and sandy loam soils. Kinetic modeling demonstrated that the pseudo second order model was the best followed by intra-particle diffusion and the Elovich model, indicating that multiple processes govern SMZ sorption. These findings were also supported by sorption edge experiments based on BC characteristics. Chemisorption onto protonated and ligand containing functional groups of the BC surface, and diffusion in macro-, meso-, and micro-pores of the acid-activated BCs are the proposed mechanisms of SMZ retention in soils. Calculated and experimental q e (amount adsorbed per kg of the adsorbent at equilibrium) values were well fitted to the pseudo second order model, and the predicted maximum equilibrium concentration of SBBC for loamy sand soils was 182 mg/kg. Overall, SBBC represents a suitable soil amendment because of its high sorption rate of SMZ in soils.

  12. Microbiological activity of soils populated by Lasius niger ants

    NASA Astrophysics Data System (ADS)

    Golichenkov, M. V.; Neimatov, A. L.; Kiryushin, A. V.

    2009-07-01

    Ants are the most widespread colonial insects assigned to the Hymenoptera order. They actively use soil as a habitat; being numerous, they create a specific microrelief. It is shown that ants affect microbiological processes of the carbon and nitrogen cycles. The carbon content in anthills remains stable throughout the growing season, and the respiration intensity is about three times higher as compared with that in the control soil. The highest methane production (0.08 nmol of CH4/g per day) in the anthill is observed at the beginning of the growing season and exceeds that in the control soil by four times. The most active nitrogen fixation (about 4 nmol of C2H4/g per h) in the anthill takes place in the early growing season, whereas, in the control soil, it is observed in the middle of the growing season. At the same time, the diazotrophic activity is higher in the control soil. The lowest denitrification in the anthill is observed at the beginning and end of the growing season. The dynamics of the denitrification in the anthill are opposite to the dynamics of the diazotrophic activity. We suppose that these regularities of the biological activity in the anthill are related to the ecology of the ants and the changes in their food preferences during the growing season.

  13. Vertical movement of iron-cyanide complexes in soils of a former Manufactured Gas Plant site

    NASA Astrophysics Data System (ADS)

    Sut, Magdalena; Repmann, Frank; Raab, Thomas

    2015-04-01

    In Germany, soil and groundwater at more than a thousand sites are contaminated with iron-cyanide complexes. These contaminations originate from the gas purification process that was conducted in Manufactured Gas Plants (MGP). The phenomenon of iron-cyanide complexes mobility in soil, according to the literature, is mainly governed by the dissolution and precipitation of ferric ferrocyanide, which is only slightly soluble (< 1 mg L-1) under acidic conditions. This study suggests vertical transport of a colloidal ferric ferrocyanide, in the excess of iron and circum-neutral pH conditions, as an alternative process that influences the retardation of the pollutant movement through the soil profile. Preliminary in situ investigations of the two boreholes implied transport of ferric ferricyanide from the initial deposition in the wastes layer towards the sandy loam material (secondary accumulation), which possibly retarded the mobility of cyanide (CN). The acidic character of the wastes and the accumulation of the blue patches suggested the potential filter function of a sandy loam material due to colloidal transport of the ferric ferricyanide. Series of batch and column experiments, using sandy loam soil, revealed reduction of CN concentration due to mechanical filtration of precipitated solid iron-cyanide complexes and due to the formation of potassium manganese iron-cyanide (K2Mn[Fe(CN)6]).

  14. Radon concentration in soil gas around local disjunctive tectonic zones in the Krakow area.

    PubMed

    Swakoń, J; Kozak, K; Paszkowski, M; Gradziński, R; Łoskiewicz, J; Mazur, J; Janik, M; Bogacz, J; Horwacik, T; Olko, P

    2005-01-01

    The purpose of this study was to investigate radon in the vicinity of geologic fault zones within the Krakow region of Poland, and to determine the influence of such formations on enhanced radon concentrations in soil. Radon ((222)Rn and (220)Rn) concentration measurements in soil gas (using ionization chamber AlphaGUARD PQ2000 PRO and diffusion chambers with CR-39 detectors), as well as radioactive natural isotopes of radium, thorium and potassium in soil samples (using gamma ray spectrometry with NaI(Tl) and HPGe detectors), were performed. Site selection was based on a geological map of Krakow. Geophysical methods (ground penetrating radar and shallow acoustic seismic) were applied to recognize the geological structure of the area and to locate the predicted courses of faults. Elevated levels of radon and thoron in soil gas were found in the study area when compared with those observed in an earlier survey covering Krakow agglomeration. For (222)Rn, the arithmetic mean of registered concentration values was 39 kBq/m(3) (median: 35.5 kBq/m(3)). For (220)Rn, the arithmetic mean was 10.8 kBq/m(3) and median 11.8 kBq/m(3).

  15. Multicomponent adsorption of polycyclic aromatic hydrocarbons in Manufactured Gas Plant soils

    SciTech Connect

    Webb, O.F.; Phelps, T.J.; Bienkowski, P.R.

    1993-01-01

    Adsorption is an important process in the bioremediation of Manufactured Gas Plant (MGP) soils contaminated with high levels of polycyclic aromatic hydrocarbons (PAH). Over 2,000 sites nationwide exist that are contaminated with complex mixtures of PAH and other pollutants. Many PAH are classified as EPA priority pollutants. The adsorption properties of weathered contaminated soils are difficult to measure using pulse or step perturbations due to heterogeneous contaminant distributions and heterogeneous soil physical structure. This study compares the use of cyclical perturbations with step change perturbations to analyze these complex soil systems. The sinusoidal method proved to be more robust than the step perturbation method. Sinusoidal response was easier to interpret and was continuous. The step change method produced a transient response that was more difficult to interpret. Two parameters, period and amplitude, were available when using sinusoidal perturbation methods while only one parameter, magnitude of the step function, was available for dynamic studies using traditional step perturbation methods. Displacement behavior was observed with both sinusoidal and step experiments. Simulations are presented using favorable isotherms for an adsorption system using a sinusoidal feed input. Automated on-line high performance liquid chromatography and capillary gas chromatography systems developed for analysis are also described.

  16. Gas chromatography - optical fiber detector for assessment of fatty acids in urban soils.

    PubMed

    Silva, Lurdes; Cachada, Anabela; Pereira, Ruth; Freitas, Ana Cristina; Rocha-Santos, Teresa A P; Panteleitchouk, Teresa S L; Pereira, Maria E; Duarte, Armando Costa

    2011-07-15

    Fatty acids have been used as biomarkers of the microbial community composition of soils and they are usually separated and quantified by gas-chromatography coupled to a flame ionization detector (GC-FID). The aim of this study was to develop, validate and apply a methodology based on gas chromatography coupled to optical fiber detection (GC-OF) for screening five fatty acids used as indicators of fungal and bacterial communities in urban soils. The performance of the GC-OF methodology (optical fiber detector at 1,550 nm) was evaluated by comparison with the GC-FID methodology and it was found that they were comparable in terms of linear range, detection limit and analytical errors. Besides these similar analytical characteristics, the GC-OF is much cheaper than the GC-FID methodology. Different concentrations were determined for each fatty acid indicator which in turn varied significantly between the soil samples analyzed from Lisbon ornamental gardens. Additionally, the GC-OF showed a great potential as alternative for determination of eleven or more fatty acids in urban soils.

  17. Methanotrophic activity and diversity of methanotrophs in volcanic geothermal soils at Pantelleria (Italy)

    NASA Astrophysics Data System (ADS)

    Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.

    2014-10-01

    Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic or geothermal soils are not only a source of methane, but are also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria (Italy), Favara Grande, whose total methane emission was previously estimated at about 2.5 Mg a-1 (t a-1). Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values of up to 59.2 nmol g-1 soil d.w. h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile, the maximum methane consumption was measured in the top-soil layer, and values greater than 6.23 nmol g-1 h-1 were still detected up to a depth of 13 cm. The highest consumption rate was measured at 37 °C, but a still detectable consumption at 80 °C (> 1.25 nmol g-1 h-1) was recorded. The soil total DNA extracted from the three samples was probed by Polymerase Chain Reaction (PCR) using standard proteobacterial primers and newly designed verrucomicrobial primers, targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected at sites FAV2 and FAV3, but not at FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site (FAV2) pointed to a high diversity of gammaproteobacterial methanotrophs, distantly related to Methylocaldum-Metylococcus genera, and the presence of the newly discovered acido-thermophilic Verrucomicrobia methanotrophs. Alphaproteobacteria of the genus Methylocystis were isolated from enrichment cultures under a methane

  18. Modeling in situ soil enzyme activity using continuous field soil moisture and temperature data

    NASA Astrophysics Data System (ADS)

    Steinweg, J. M.; Wallenstein, M. D.

    2010-12-01

    Moisture and temperature are key drivers of soil organic matter decomposition, but there is little consensus on how climate change will affect the degradation of specific soil compounds under field conditions. Soil enzyme activities are a useful metric of soil community microbial function because they are they are the direct agents of decomposition for specific substrates in soil. However, current standard enzyme assays are conducted under optimized conditions in the laboratory and do not accurately reflect in situ enzyme activity, where diffusion and substrate availability may limit reaction rates. The Arrhenius equation, k= A*e(-Ea/RT), can be used to predict enzyme activity (k), collision frequency (A) or activation energy (Ea), but is difficult to parameterize when activities are measured under artificial conditions without diffusion or substrate limitation. We developed a modifed equation to estimate collision frequency and activation energy based on soil moisture to model in-situ enzyme activites. Our model was parameterized using data we collected from the Boston Area Climate Experiment (BACE) in Massachusetts; a multi-factor climate change experiment that provides an opportunity to assess how changes in moisture availability and temperature may impact enzyme activity. Soils were collected from three precipitation treatments and four temperature treatments arranged in a full-factorial design at the BACE site in June 2008, August 2008, January 2009 and June 2009. Enzyme assays were performed at four temperatures (4, 15, 25 and 35°C) to calculate temperature sensitivity and activation energy over the different treatments and seasons. Enzymes activities were measured for six common enzymes involved in carbon (β-glucosidase, cellobiohydrolase, xylosidase), phosphorus (phosphatase) and nitrogen cycling (N-acetyl glucosaminidase, and leucine amino peptidase). Potential enzyme activity was not significantly affected by precipitation, warming or the interaction of

  19. Estimation of net greenhouse gas balance using crop- and soil-based approaches: two case studies.

    PubMed

    Huang, Jianxiong; Chen, Yuanquan; Sui, Peng; Gao, Wansheng

    2013-07-01

    The net greenhouse gas balance (NGHGB), estimated by combining direct and indirect greenhouse gas (GHG) emissions, can reveal whether an agricultural system is a sink or source of GHGs. Currently, two types of methods, referred to here as crop-based and soil-based approaches, are widely used to estimate the NGHGB of agricultural systems on annual and seasonal crop timescales. However, the two approaches may produce contradictory results, and few studies have tested which approach is more reliable. In this study, we examined the two approaches using experimental data from an intercropping trial with straw removal and a tillage trial with straw return. The results of the two approaches provided different views of the two trials. In the intercropping trial, NGHGB estimated by the crop-based approach indicated that monocultured maize (M) was a source of GHGs (-1315 kg CO₂(-eq)ha(-1)), whereas maize-soybean intercropping (MS) was a sink (107 kg CO₂(-eq)ha(-1)). When estimated by the soil-based approach, both cropping systems were sources (-3410 for M and -2638 kg CO₂(-eq)ha(-1) for MS). In the tillage trial, mouldboard ploughing (MP) and rotary tillage (RT) mitigated GHG emissions by 22,451 and 21,500 kg CO₂(-eq)ha(-1), respectively, as estimated by the crop-based approach. However, by the soil-based approach, both tillage methods were sources of GHGs: -3533 for MP and -2241 kg CO₂(-eq)ha(-1) for RT. The crop-based approach calculates a GHG sink on the basis of the returned crop biomass (and other organic matter input) and estimates considerably more GHG mitigation potential than that calculated from the variations in soil organic carbon storage by the soil-based approach. These results indicate that the crop-based approach estimates higher GHG mitigation benefits compared to the soil-based approach and may overestimate the potential of GHG mitigation in agricultural systems.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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

  1. Gobar gas (biogas) survey in Nepal - 1979; a survey of three community biogas plants in Nepal - 1980; survey of present gobar gas work in India; and night soil gas plant

    SciTech Connect

    Bulmer, A.; Schlorholtz, A.; Fulford, D.J.; Peters, N.

    1980-01-01

    The first of these documents investigates the success of a project to bring the use of Biogas to Nepal. 50 users and 24 non-users were interviewed. The conclusions were that use of biogas in Nepal is successful, providing clean kitchens, healthier lives, and saving forests. They cause no social problems, but the service company for the plants needs improvement. The second report shows that community plants relying on continued cooperation are fragile enterprises. One of the plants ended up being run by one family, the gas distributed according to the dung input by each family. The gas was not used fully. Technical problems were partly responsible for this. In the second village technical problems and social problems reduced the number of users to 5 families from 26. In the third case the plant fell into disrepair but the social pattern of using a common area for defecation to fill the plant benefitted from having a permanent enclosure built. This scheme charged for use of the gas to help run the plant but the technical and social problems stymied correction. The third report lists the activities of various gobar gas research stations in India. The fourth report gives directions and specifications to build a night soil gas plant, including working drawings.

  2. Assessment of Soil-Gas, Surface-Water, and Soil Contamination at the Installation Railhead, Fort Gordon, Georgia, 2008-2009

    USGS Publications Warehouse

    Landmeyer, James E.; Harrelson, Larry G.; Ratliff, W. Hagan; Wellborn, John B.

    2010-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of the Army Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon, assessed soil gas, surface water, and soil for contaminants at the Installation Railhead (IR) at Fort Gordon, Georgia, from October 2008 to September 2009. The assessment included delineation of organic contaminants present in soil-gas samples beneath the IR, and in a surface-water sample collected from an unnamed tributary to Marcum Branch in the western part of the IR. Inorganic contaminants were determined in a surface-water sample and in soil samples. This assessment was conducted to provide environmental contamination data to Fort Gordon personnel pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Soil-gas samples collected within a localized area on the western part of the IR contained total petroleum hydrocarbons; benzene, toluene, ethylbenzene, and total xylenes (referred to as BTEX); and naphthalene above the method detection level. These soil-gas samples were collected where buildings had previously stood. Soil-gas samples collected within a localized area contained perchloroethylene (PCE). These samples were collected where buildings 2410 and 2405 had been. Chloroform and toluene were detected in a surface-water sample collected from an unnamed tributary to Marcum Branch but at concentrations below the National Primary Drinking Water Standard maximum contaminant level (MCL) for each compound. Iron was detected in the surface-water sample at 686 micrograms per liter (ug/L) and exceeded the National Secondary Drinking Water Standard MCL for iron. Metal concentrations in composite soil samples collected at three locations from land surface to a depth of 6 inches did not exceed the U.S. Environmental Protection Agency Regional Screening Levels for industrial soil.

  3. Spatial variability of the dehydrogenase activity in forest soils

    NASA Astrophysics Data System (ADS)

    Błońska, Ewa; Lasota, Jarosław

    2014-05-01

    The aim of this study was to assess the spatial variability of the dehydrogenase activity (DH) in forest soils using geostatistics. We have studied variability soil dehydrogenase and their relationship with variability of some physic-chemical properties. Two study areas (A and B) were set up in southern Poland in the Zlotoryja Forest District. Study areas were covered by different types of vegetation (A- broadleaf forest with beech, ash and sycamore), B- coniferous forest with Norway spruce). The soils were classified as Dystric Cambisols (WRB 2006). The samples for laboratory testing were collected from 49 places on each areas. 15 cm of surface horizon of soil were taken (with previously removed litter). Dehydrogenase activity was marked with Lenhard's method according to the Casida procedure. Soil pH, nitrogen (N) and soil organic carbon (C) content (by LECO CNS 2000 carbon analyzer) was marked. C/N ratio was calculated. Particle size composition was determined using laser diffraction. Statistical analysis were performed using STATISTICA 10 software. Geostatistical analysis and mapping were done by application of GS 9+ (Gamma Design) and Surfer 11 (Golden Software). The activity of DH ranged between 5,02 and 71,20 mg TPP• kg-1 •24 h-1 on the A area and between 0,94 and 16,47 mg TPP• kg-1 •24 h-1. Differences in spatial variability of the analised features were noted. The variability of dehydrogenase activity on the A study area was described by an exponential model, whereas on the B study area the spatial correlation has not been noted. The relationship of dehydrogenase activity with the remaining parameters of soil was noted only in the case of A study area. The variability of organic carbon content on the A and B study areas were described by an exponential model. The variability of nitrogen content on both areas were described by an spherical model.

  4. Ice Nucleation Activity in the Widespread Soil Fungus Mortierella alpina

    NASA Astrophysics Data System (ADS)

    Fröhlich-Nowoisky, J.; Hill, T. C. J.; Pummer, B. G.; Franc, G. D.; Pöschl, U.

    2014-08-01

    Biological residues in soil dust are a potentially strong source of atmospheric ice nuclei (IN). So far, however, the abundance, diversity, sources, seasonality, and role of biological - in particular, fungal - IN in soil dust have not been characterized. By analysis of the culturable fungi in topsoils, from a range of different land use and ecosystem types in south-east Wyoming, we found ice nucleation active (INA) fungi to be both widespread and abundant, particularly in soils with recent inputs of decomposable organic matter. Across all investigated soils, 8% of fungal isolates were INA. All INA isolates initiated freezing at -5 to -6 °C, and belonged to a single zygomycotic species, Mortierella alpina (Mortierellales, Mortierellomycotina). By contrast, the handful of fungal species so far reported as INA all belong within the Ascomycota or Basidiomycota phyla. M. alpina is known to be saprobic, widespread in soil and present in air and rain. Sequencing of the ITS region and the gene for γ-linolenic-elongase revealed four distinct clades, affiliated to different soil types. The IN produced by M. alpina seem to be proteinaceous, <300 kDa in size, and can be easily washed off the mycelium. Ice nucleating fungal mycelium will ramify topsoils and probably also release cell-free IN into it. If these IN survive decomposition or are adsorbed onto mineral surfaces, their contribution might accumulate over time, perhaps to be transported with soil dust and influencing its ice nucleating properties.

  5. Seasonal and spatial variations in Rn-222 and Rn-220 in soil gas, and implications for indoor radon levels.

    PubMed

    Sharman, G

    1992-12-01

    Rn-222 enters dwellings as a component of soil gas drawn from the soil by mass flow driven by the pressure difference between the house and soil beneath. In a site on Northampton Sand Ironstone (Aalenian), a preferred path of emanation (hotspot) was found. A difference of 63 Bq L(-1) Rn-222 was recorded in July between this point and another 3 m away. Rn-222 in this hotspot shows 12% less variation annually than the surrounding rock. During winter, Rn-222 values within 1.6 m of the house were 44% lower than those at more than 4 m away. Rn-222 showed a 99.5% negative correlation with wind run, showing that on this soil wind pressure can significantly reduce radon in the soil at 500 mm depth. Rn-220 in soil gas correlated positively at the 99.5% level with grass and air temperatures. Rn-220 was not associated with the hotspot.

  6. Temperature sensitivity of microbial respiration, nitrogen mineralization, and potential soil enzyme activities in organic alpine soils

    NASA Astrophysics Data System (ADS)

    Koch, Oliver; Tscherko, Dagmar; Kandeler, Ellen

    2007-12-01

    Investigations focusing on the temperature sensitivity of microbial activity and nutrient turnover in soils improve our understanding of potential effects of global warming. This study investigates the temperature sensitivity of C mineralization, N mineralization, and potential enzyme activities involved in the C and N cycle (tyrosine amino-peptidase, leucine amino-peptidase, ß-glucosidase, ß-xylosidase, N-acetyl-ß-glucosaminidase). Four different study sites in the Austrian alpine zone were selected, and soils were sampled in three seasons (summer, autumn, and winter). A simple first-order exponential equation was used to calculate constant Q10 values for the C and N mineralization over the investigated temperature range (0-30°C). The Q10 values of the C mineralization (average 2.0) for all study sites were significantly higher than for the N mineralization (average 1.7). The Q10 values of both activities were significantly negatively related to a soil organic matter quality index calculated by the ratios of respiration to the organic soil carbon and mineralized N to the total soil nitrogen. The chemical soil properties or microbial biomass did not affect the Q10 values of C and N mineralization. Moreover, the Q10 values showed no distinct pattern according to sampling date, indicating that the substrate quality and other factors are more important. Using a flexible model function, the analysis of relative temperature sensitivity (RTS) showed that the temperature sensitivity of activities increased with decreasing temperature. The C and N mineralization and potential amino-peptidase activities (tyrosine and leucine) showed an almost constant temperature dependence over 0-30°C. In contrast, ß-glucosidase, ß-xylosidase, and N-acetyl-ß-glucosaminidase showed a distinctive increase in temperature sensitivity with decreasing temperature. Low temperature at the winter sampling date caused a greater increase in the RTS of all microbial activities than for the

  7. Impact of earthworm Lumbricus terrestris living sites on the greenhouse gas balance of no-till arable soil

    NASA Astrophysics Data System (ADS)

    Nieminen, M.; Hurme, T.; Mikola, J.; Regina, K.; Nuutinen, V.

    2015-09-01

    We studied the effect of the deep-burrowing earthworm Lumbricus terrestris on the greenhouse gas (GHG) fluxes and global warming potential (GWP) of arable no-till soil using both field measurements and a controlled 15-week laboratory experiment. In the field, the emissions of nitrous oxide (N2O) and carbon dioxide (CO2) were on average 43 and 32 % higher in areas occupied by L. terrestris (the presence judged by the surface midden) than in adjacent, unoccupied areas (with no midden). The fluxes of methane (CH4) were variable and had no consistent difference between the midden and non-midden areas. Removing the midden did not affect soil N2O and CO2 emissions. The laboratory results were consistent with the field observations in that the emissions of N2O and CO2 were on average 27 and 13 % higher in mesocosms with than without L. terrestris. Higher emissions of N2O were most likely due to the higher content of mineral nitrogen and soil moisture under the middens, whereas L. terrestris respiration fully explained the observed increase in CO2 emissions in the laboratory. In the field, the significantly elevated macrofaunal densities in the vicinity of middens likely contributed to the higher emissions from areas occupied by L. terrestris. The activity of L. terrestris increased the GWP of field and laboratory soil by 50 and 18 %, but only 6 and 2 % of this increase was due to the enhanced N2O emission. Our results suggest that high N2O emissions commonly observed in no-till soils can partly be explained by the abundance of L. terrestris under no-till management and that L. terrestris can markedly regulate the climatic effects of different cultivation practises.

  8. Determination of pesticides in soil by liquid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Hou, Li; Lee, Hian Kee

    2004-06-04

    Trace amounts of pesticides in soil were determined by liquid-phase microextraction (LPME) coupled to gas chromatography-mass spectrometry (GC-MS). The technique involved the use of a small amount (3 microl) of organic solvent impregnated in a hollow fiber membrane, which was attached to the needle of a conventional GC syringe. The organic solvent was repeatedly discharged into and withdrawn from the porous polypropylene hollow fiber by a syringe pump, with the pesticides being extracted from a 4 ml aqueous soil sample into the organic solvent within the hollow fiber. Aspects of the developed procedure such as organic solvent selection, extraction time, movement pattern of plunger, concentrations of humic acid and salt, and the proportion of organic solvent in the soil sample, were optimized. Limits of detection (LOD) were between 0.05 and 0.1 microg/g with GC-MS analysis under selected-ion monitoring (SIM). Also, this method provided good precision ranging from 6 to 13%; the relative standard deviations were lower than 10% for most target pesticides (at spiked levels of 0.5 microg/g in aqueous soil sample). Finally, the results were compared to those achieved using solid-phase microextraction (SPME). The results demonstrated that LPME was a fast (within 4 min) and accurate method to determine trace amounts of pesticides in soil.

  9. Neutron activation analysis of thermal power plant ash and surrounding area soils.

    PubMed

    Al-Masri, M S; Haddad, Kh; Alsomel, N; Sarhil, A

    2015-08-01

    Elemental concentrations of As, Cd, Co, Cr, Fe, Hg, Mo, Ni, Se, and Zn have been determined in fly and bottom ash collected from Syrian power plants fired by heavy oil and natural gas using instrumental neutron activation analysis. The results showed that all elements were more concentrated in fly ash than in the fly ash; there was a clear increasing trend of the elemental concentrations in the fly ash along the flue gas pathway. The annual emission of elements was estimated. Elemental concentrations were higher inside the campus area than in surrounding areas, and the lowest values were found in natural-gas-fired power plant. In addition, the levels have decreased as the distance from power plant campus increases. However, the levels in the surrounding villages were within the Syrian standard for agriculture soil.

  10. Methane gas concentration in soils and ground water, Carbon and Emery Counties, Utah, 1995-2003

    USGS Publications Warehouse

    Stolp, B.J.; Burr, A.L.; Johnson, K.K.

    2006-01-01

    The release of methane gas from coal beds creates the potential for it to move into near-surface environments through natural and human-made pathways. To help ensure the safety of communities and determine the potential effects of development of coal-bed resources, methane gas concentrations in soils and ground water in Carbon and Emery Counties, Utah, were monitored from 1995 to 2003. A total of 420 samples were collected, which contained an average methane concentration of 2,740 parts per million by volume (ppmv) and a median concentration of less than 10 ppmv. On the basis of spatial and temporal methane concentration data collected during the monitoring period, there does not appear to be an obvious, widespread, or consistent migration of methane gas to the near-surface environment.

  11. Greenhouse gas emission and groundwater pollution potential of soils amended with raw swine manure, dry and wet pyrolyzed swine biochars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research is to study the greenhouse gas emission and groundwater pollution potentials of the soils amended with raw swine solid and swine biochars made from different thermochemical conditions. Triplicate sets of small pots were designed: 1) control soil with a 50/50 mixture of...

  12. Biochar and manure effects on net nitrogen mineralization and greenhouse gas emissions from calcareous soil under corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Few multiyear field studies have examined the impacts of a one-time biochar application on net N mineralization and greenhouse gas emissions in an irrigated, calcareous soil; yet such applications are hypothesized as a means of sequestering atmospheric CO2 and improving soil quality. We fall-applie...

  13. Co-generated fast pyrolysis biochar mitigates green-house gas emissions and increases carbon sequestration in temperate soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar (BC) is a product of thermochemical conversion of biomass via pyrolysis, together with gas (syngas), liquid (bio-oil), and heat. Fast pyrolysis is a promising process for bio-oil generation, which leaves 10-30% of the original biomass as char. When applied to soils, BC may increase soil C s...

  14. Use of animal waste and flue gas desulfurized gypsum to improve forage production on reclaimed mine soil in Mississippi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reclaimed mine soils amended with flue gas desulfurized (FGD) gypsum may tolerate higher levels of animal manure, and would therefore be more productive in the long-term. Studies were conducted in respread soil during the first year of land reclamation at Red Hills Mine, a surface lignite mine in no...

  15. Seasonal greenhouse gas and soil nutrient cycling in semi-arid native and non-native perennial grass pastures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous research indicates that a difference occurs in native and non-native grass species in regard to drivers of greenhouse gas (GHG, (carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O))) emissions from soil. Drivers of soil nutrients could help establish best management practices to mit...

  16. Diversity and Activity of Lysobacter Species from Disease Suppressive Soils

    PubMed Central

    Gómez Expósito, Ruth; Postma, Joeke; Raaijmakers, Jos M.; De Bruijn, Irene

    2015-01-01

    The genus Lysobacter includes several species that produce a range of extracellular enzymes and other metabolites with activity against bacteria, fungi, oomycetes, and nematodes. Lysobacter species were found to be more abundant in soil suppressive against the fungal root pathogen Rhizoctonia solani, but their actual role in disease suppression is still unclear. Here, the antifungal and plant growth-promoting activities of 18 Lysobacter strains, including 11 strains from Rhizoctonia-suppressive soils, were studied both in vitro and in vivo. Based on 16S rRNA sequencing, the Lysobacter strains from the Rhizoctonia-suppressive soil belonged to the four species Lysobacter antibioticus, Lysobacter capsici, Lysobacter enzymogenes, and Lysobacter gummosus. Most strains showed strong in vitro activity against R. solani and several other pathogens, including Pythium ultimum, Aspergillus niger, Fusarium oxysporum, and Xanthomonas campestris. When the Lysobacter strains were introduced into soil, however, no significant and consistent suppression of R. solani damping-off disease of sugar beet and cauliflower was observed. Subsequent bioassays further revealed that none of the Lysobacter strains was able to promote growth of sugar beet, cauliflower, onion, and Arabidopsis thaliana, either directly or via volatile compounds. The lack of in vivo activity is most likely attributed to poor colonization of the rhizosphere by the introduced Lysobacter strains. In conclusion, our results demonstrated that Lysobacter species have strong antagonistic activities against a range of pathogens, making them an important source for putative new enzymes and antimicrobial compounds. However, their potential role in R. solani disease suppressive soil could not be confirmed. In-depth omics'–based analyses will be needed to shed more light on the potential contribution of Lysobacter species to the collective activities of microbial consortia in disease suppressive soils. PMID:26635735

  17. EU strategies and policies on soil and waste management to offset greenhouse gas emissions.

    PubMed

    Marmo, L

    2008-01-01

    Climate change has become an important political priority in the environmental field, and beyond. To revert the increase in the Earth's temperature, developed country parties to the Kyoto Protocol committed to limit their greenhouse gas emissions. The 15 Member States that made up the European Community in 1997 have a combined reduction target of 8% in CO2-equivalent emissions in the period 2008-2012 compared to 1990. The role of soil, both as a source and a sink for carbon, is particularly important. How can soil organic matter be maintained or increased? There is no single answer, and a broad range of options need to be explored. Among the different measures proposed, the promotion of organic input on arable land (crop residues, cover crops, farm yard manure, compost, sewage sludge) has been mentioned. The challenge is to ensure that organic wastes of good quality are used to increase soil organic matter in carbon depleted soils and that appropriate monitoring is established. On the waste management front, the European Commission intends to produce guidance for Member States on the management of biowaste that will take into account all related environmental issues, including soil aspects. As for monitoring, the European Commission has put forward legislation according to which Member States would have to identify the areas at risk of soil organic matter decline in their national territory. Such legislation should be regarded as a major step forward for Europe, as it would ensure a high level of soil protection across the Community. This development will have the potential to enable the kind of estimation, measurement or modelling of crop or grazing land management needed for accounting under Article 3.4 of the Kyoto Protocol.

  18. Soil hydrological and soil property changes resulting from termite activity on agricultural fields in Burkina Faso

    NASA Astrophysics Data System (ADS)

    Mettrop, I.; Cammeraat, L. H.; Verbeeten, E.

    2009-04-01

    Termites are important ecosystem-engineers in subtropical and tropical regions. The effect of termite activity affecting soil infiltration is well documented in the Sahelian region. Most studies find increased infiltration rates on surfaces that are affected by termite activity in comparison to crusted areas showing non-termite presence. Crusted agricultural fields in the Sanmatenga region in Burkina Faso with clear termite activity were compared to control fields without visual ground dwelling termite activity. Fine scale rainfall simulations were carried out on crusted termite affected and control sites. Furthermore soil moisture change, bulk density, soil organic matter as well as general soil characteristics were studied. The top soils in the study area were strongly crusted (structural crust) after the summer rainfall and harvest of millet. They have a loamy sand texture underlain by a shallow sandy loam Bt horizon. The initial soil moisture conditions were significantly higher on the termite plots when compared to control sites. It was found that the amount of runoff produced on the termite plots was significantly higher, and also the volumetric soil moisture content after the experiments was significantly lower if compared to the control plots. Bulk density showed no difference whereas soil organic matter was significantly higher under termite affected areas, in comparison to the control plots. Lab tests showed no significant difference in hydrophobic behavior of the topsoil and crust material. Micro and macro-structural properties of the topsoil did not differ significantly between the termite sites and the control sites. The texture of the top 5 cm of the soil was also found to be not significantly different. The infiltration results are contradictory to the general literature, which reports increased infiltration rates after prolonged termite activity although mostly under different initial conditions. The number of nest entrances was clearly higher in

  19. Impact of interspecific interactions on antimicrobial activity among soil bacteria.

    PubMed

    Tyc, Olaf; van den Berg, Marlies; Gerards, Saskia; van Veen, Johannes A; Raaijmakers, Jos M; de Boer, Wietse; Garbeva, Paolina

    2014-01-01

    Certain bacterial species produce antimicrobial compounds only in the presence of a competing species. However, little is known on the frequency of interaction-mediated induction of antibiotic compound production in natural communities of soil bacteria. Here we developed a high-throughput method to screen for the production of antimicrobial activity by monocultures and pair-wise combinations of 146 phylogenetically different bacteria isolated from similar soil habitats. Growth responses of two human pathogenic model organisms, Escherichia coli WA321 and Staphylococcus aureus 533R4, were used to monitor antimicrobial activity. From all isolates, 33% showed antimicrobial activity only in monoculture and 42% showed activity only when tested in interactions. More bacterial isolates were active against S. aureus than against E. coli. The frequency of interaction-mediated induction of antimicrobial activity was 6% (154 interactions out of 2798) indicating that only a limited set of species combinations showed such activity. The screening revealed also interaction-mediated suppression of antimicrobial activity for 22% of all combinations tested. Whereas all patterns of antimicrobial activity (non-induced production, induced production and suppression) were seen for various bacterial classes, interaction-mediated induction of antimicrobial activity was more frequent for combinations of Flavobacteria and alpha- Proteobacteria. The results of our study give a first indication on the frequency of interference competitive interactions in natural soil bacterial communities which may forms a basis for selection of bacterial groups that are promising for the discovery of novel, cryptic antibiotics.

  20. [Responses of soil enzyme activities to re-vegetation in gully Loess Plateau of Northwest China].

    PubMed

    Li, Lin-Hai; Qiu, Li-Ping; Meng, Meng

    2012-12-01

    In combining field investigation with laboratory analysis, this paper studied the distribution characteristics of soil enzyme activities along the soil profiles and natural slopes with different re-vegetation treatments in gully Loess Plateau, aimed to assess the responses of the soil enzyme activities to re-vegetation. In the study area, the activities of soil urease, invertase and alkaline phosphatase along natural slopes were highly varied, but the activity of soil catalase was in adverse. The profile distribution of the soil enzyme activities varied significantly with vegetation type, and with increasing soil depth, the activities of soil urease, invertase and alkaline phosphatase decreased while the catalase activity increased. There existed significant positive correlation among the three hydrolases activities. The activities of the three hydrolases were all significantly negatively correlated with soil physical properties and positively correlated with soil chemical properties, while the soil catalase activity was positively correlated with soil moisture content and pH and negatively correlated with other soil physiochemical properties. It was suggested that the activities of soil urease, invertase and alkaline phosphatase in gully Loess Plateau could be used as the sensitive indicators for the soil responses to the re-vegetation in the Plateau, and re-vegetation could improve the biological properties in both surface and deeper soil layers.

  1. Soil extracellular enzyme activities, soil carbon and nitrogen storage under nitrogen fertilization: A meta-analysis

    SciTech Connect

    Jian, Siyang; Li, Jianwei; Chen, Ji; Wang, Gangsheng; Mayes, Melanie A.; Dzantor, Kudjo E.; Hui, Dafeng; Luo, Yiqi

    2016-07-08

    Nitrogen (N) fertilization affects the rate of soil organic carbon (SOC) decomposition by regulating extracellular enzyme activities (EEA). Extracellular enzymes have not been represented in global biogeochemical models. Understanding the relationships among EEA and SOC, soil N (TN), and soil microbial biomass carbon (MBC) under N fertilization would enable modeling of the influence of EEA on SOC decomposition. Based on 65 published studies, we synthesized the activities of α-1,4-glucosidase (AG), β-1,4-glucosidase (BG), β-d-cellobiosidase (CBH), β-1,4-xylosidase (BX), β-1,4-N-acetyl-glucosaminidase (NAG), leucine amino peptidase (LAP), urease (UREA), acid phosphatase (AP), phenol oxidase (PHO), and peroxidase (PEO) in response to N fertilization. Here, the proxy variables for hydrolytic C acquisition enzymes (C-acq), N acquisition (N-acq), and oxidative decomposition (OX) were calculated as the sum of AG, BG, CBH and BX; AG and LAP; PHO and PEO, respectively.

  2. Biological activity of soil contaminated with cobalt, tin, and molybdenum.

    PubMed

    Zaborowska, Magdalena; Kucharski, Jan; Wyszkowska, Jadwiga

    2016-07-01

    In this age of intensive industrialization and urbanization, mankind's highest concern should be to analyze the effect of all metals accumulating in the environment, both those considered toxic and trace elements. With this aim in mind, a unique study was conducted to determine the potentially negative impact of Sn(2+), Co(2+), and Mo(5+) in optimal and increased doses on soil biological properties. These metals were applied in the form of aqueous solutions of Sn(2+) (SnCl2 (.)2H2O), Co(2+) (CoCl2 · 6H2O), and Mo(5+) (MoCl5), each in the doses of 0, 25, 50, 100, 200, 400, and 800 mg kg(-1) soil DM. The activity of dehydrogenases, urease, acid phosphatase, alkaline phosphatase, arylsulfatase, and catalase and the counts of twelve microorganism groups were determined on the 25th and 50th day of experiment duration. Moreover, to present the studied problem comprehensively, changes in the biochemical activity and yield of spring barley were shown using soil and plant resistance indices-RS. The study shows that Sn(2+), Co(2+), and Mo(5+) disturb the state of soil homeostasis. Co(2+) and Mo(5+) proved the greatest soil biological activity inhibitors. The residence of these metals in soil, particularly Co(2+), also generated a drastic decrease in the value of spring barley resistance. Only Sn(2+) did not disrupt its yielding. The studied enzymes can be arranged as follows for their sensitivity to Sn(2+), Co(2+), Mo(5+): Deh > Ure > Aryl > Pal > Pac > Cat. Dehydrogenases and urease may be reliable soil health indicators.

  3. Ten years of soil CO2 continuous monitoring on Mt. Etna: Exploring the relationship between processes of soil degassing and volcanic activity

    NASA Astrophysics Data System (ADS)

    Liuzzo, Marco; Gurrieri, Sergio; Giudice, Gaetano; Giuffrida, Giovanni

    2013-08-01

    The measurement of soil CO2 flux variations is a well-established practice in many volcanic areas around the world. Until recently, however, most of these were made using direct sampling methods. These days, a variety of automatic devices providing real-time data now make the continuous monitoring of volcanic areas possible. A network of automatic geochemical monitoring stations (EtnaGas network) was developed by INGV Palermo and installed at various sites on the flanks of Mt. Etna. Here, we present a large set of soil CO2 flux data recorded by the network, dating back 10 years, a period in which several noteworthy eruptive phenomena occurred. Our statistical analysis strongly suggests that anomalous measurements of soil CO2 flux are attributable to volcanic origin and in almost all cases precede volcanic activity. Here, we present the actual data series recorded by EtnaGAS and an interpretative model of the expected behavior of soil CO2 flux (in terms of increase-decrease cycles), which corresponded well with the volcanic activity during this period. Through the use of a comparative approach, incorporating both volcanological and geochemical data, the global soil CO2 flux trends are put into a coherent framework, highlighting close links between the time flux variations and volcanic activities. These insights, made possible from 10 years of uninterrupted data, confirm the importance of continuous monitoring of volcanic soil degassing, and may contribute in the forecasting of imminent eruptive activity or the temporal evolution of an in-progress eruption, therefore facilitating Civil Defense planning in volcanic areas under high-hazard conditions.

  4. Predicting greenhouse gas emissions and soil carbon from changing pasture to an energy crop.

    PubMed

    Duval, Benjamin D; Anderson-Teixeira, Kristina J; Davis, Sarah C; Keogh, Cindy; Long, Stephen P; Parton, William J; DeLucia, Evan H

    2013-01-01

    Bioenergy related land use change would likely alter biogeochemical cycles and global greenhouse gas budgets. Energy cane (Saccharum officinarum L.) is a sugarcane variety and an emerging biofuel feedstock for cellulosic bio-ethanol production. It has potential for high yields and can be grown on marginal land, which minimizes competition with grain and vegetable production. The DayCent biogeochemical model was parameterized to infer potential yields of energy cane and how changing land from grazed pasture to energy cane would affect greenhouse gas (CO2, CH4 and N2O) fluxes and soil C pools. The model was used to simulate energy cane production on two soil types in central Florida, nutrient poor Spodosols and organic Histosols. Energy cane was productive on both soil types (yielding 46-76 Mg dry mass · ha(-1)). Yields were maintained through three annual cropping cycles on Histosols but declined with each harvest on Spodosols. Overall, converting pasture to energy cane created a sink for GHGs on Spodosols and reduced the size of the GHG source on Histosols. This change was driven on both soil types by eliminating CH4 emissions from cattle and by the large increase in C uptake by greater biomass production in energy cane relative to pasture. However, the change from pasture to energy cane caused Histosols to lose 4493 g CO2 eq · m(-2) over 15 years of energy cane production. Cultivation of energy cane on former pasture on Spodosol soils in the southeast US has the potential for high biomass yield and the mitigation of GHG emissions.

  5. Predicting Greenhouse Gas Emissions and Soil Carbon from Changing Pasture to an Energy Crop

    PubMed Central

    Duval, Benjamin D.; Anderson-Teixeira, Kristina J.; Davis, Sarah C.; Keogh, Cindy; Long, Stephen P.; Parton, William J.; DeLucia, Evan H.

    2013-01-01

    Bioenergy related land use change would likely alter biogeochemical cycles and global greenhouse gas budgets. Energy cane (Saccharum officinarum L.) is a sugarcane variety and an emerging biofuel feedstock for cellulosic bio-ethanol production. It has potential for high yields and can be grown on marginal land, which minimizes competition with grain and vegetable production. The DayCent biogeochemical model was parameterized to infer potential yields of energy cane and how changing land from grazed pasture to energy cane would affect greenhouse gas (CO2, CH4 and N2O) fluxes and soil C pools. The model was used to simulate energy cane production on two soil types in central Florida, nutrient poor Spodosols and organic Histosols. Energy cane was productive on both soil types (yielding 46–76 Mg dry mass⋅ha−1). Yields were maintained through three annual cropping cycles on Histosols but declined with each harvest on Spodosols. Overall, converting pasture to energy cane created a sink for GHGs on Spodosols and reduced the size of the GHG source on Histosols. This change was driven on both soil types by eliminating CH4 emissions from cattle and by the large increase in C uptake by greater biomass production in energy cane relative to pasture. However, the change from pasture to energy cane caused Histosols to lose 4493 g CO2 eq⋅m−2 over 15 years of energy cane production. Cultivation of energy cane on former pasture on Spodosol soils in the southeast US has the potential for high biomass yield and the mitigation of GHG emissions. PMID:23991028

  6. [Vertical distribution of soil active carbon and soil organic carbon storage under different forest types in the Qinling Mountains].

    PubMed

    Wang, Di; Geng, Zeng-Chao; She, Diao; He, Wen-Xiang; Hou, Lin

    2014-06-01

    Adopting field investigation and indoor analysis methods, the distribution patterns of soil active carbon and soil carbon storage in the soil profiles of Quercus aliena var. acuteserrata (Matoutan Forest, I), Pinus tabuliformis (II), Pinus armandii (III), pine-oak mixed forest (IV), Picea asperata (V), and Quercus aliena var. acuteserrata (Xinjiashan Forest, VI) of Qinling Mountains were studied in August 2013. The results showed that soil organic carbon (SOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), and easily oxidizable carbon (EOC) decreased with the increase of soil depth along the different forest soil profiles. The SOC and DOC contents of different depths along the soil profiles of P. asperata and pine-oak mixed forest were higher than in the other studied forest soils, and the order of the mean SOC and DOC along the different soil profiles was V > IV > I > II > III > VI. The contents of soil MBC of the different forest soil profiles were 71.25-710.05 mg x kg(-1), with a content sequence of I > V > N > III > II > VI. The content of EOC along the whole soil profile of pine-oak mixed forest had a largest decline, and the order of the mean EOC was IV > V> I > II > III > VI. The sequence of soil organic carbon storage of the 0-60 cm soil layer was V > I >IV > III > VI > II. The MBC, DOC and EOC contents of the different forest soils were significanty correlated to each other. There was significant positive correlation among soil active carbon and TOC, TN. Meanwhile, there was no significant correlation between soil active carbon and other soil basic physicochemical properties.

  7. Phenol oxidase activity in secondary transformed peat-moorsh soils

    NASA Astrophysics Data System (ADS)

    Styła, K.; Szajdak, L.

    2009-04-01

    The chemical composition of peat depends on the geobotanical conditions of its formation and on the depth of sampling. The evolution of hydrogenic peat soils is closely related to the genesis of peat and to the changes in water conditions. Due to a number of factors including oscillation of ground water level, different redox potential, changes of aerobic conditions, different plant communities, and root exudes, and products of the degradation of plant remains, peat-moorsh soils may undergo a process of secondary transformation conditions (Sokolowska et al. 2005; Szajdak et al. 2007). Phenol oxidase is one of the few enzymes able to degrade recalcitrant phenolic materials as lignin (Freeman et al. 2004). Phenol oxidase enzymes catalyze polyphenol oxidation in the presence of oxygen (O2) by removing phenolic hydrogen or hydrogenes to from radicals or quinines. These products undergo nucleophilic addition reactions in the presence or absence of free - NH2 group with the eventual production of humic acid-like polymers. The presence of phenol oxidase in soil environments is important in the formation of humic substances a desirable process because the carbon is stored in a stable form (Matocha et al. 2004). The investigations were carried out on the transect of peatland 4.5 km long, located in the Agroecological Landscape Park host D. Chlapowski in Turew (40 km South-West of Poznań, West Polish Lowland). The sites of investigation were located along Wyskoć ditch. The following material was taken from four chosen sites marked as Zbechy, Bridge, Shelterbelt and Hirudo in two layers: cartel (0-50cm) and cattle (50-100cm). The object of this study was to characterize the biochemical properties by the determination of the phenol oxidize activity in two layers of the four different peat-moors soils used as meadow. The phenol oxidase activity was determined spectrophotometrically by measuring quinone formation at λmax=525 nm with catechol as substrate by method of Perucci

  8. Development of an improved active gas target design for ANASEN

    NASA Astrophysics Data System (ADS)

    Schill, Sabina; Blackmon, J. C.; Deibel, C. M.; Macon, K. T.; Rasco, B. C.; Wiedenhoever, I.

    2014-09-01

    The Array for Nuclear Astrophysics and Structure with Exotic Nuclei (ANASEN) is a charged particle detector array with an active gas target-detector capability for sensitive measurements using radioactive ion beams. One of the main goals is to improve our understanding of nuclear reactions important in stellar explosions. Following initial experimental campaigns with ANASEN, we have been developing an improved active gas target design for ANASEN that incorporates an innovative cylindrical gas ionization detector for heavy ions surrounding the beam axis inside of the other ANASEN charged particle detectors. The detection of heavy ions in coincidence with lighter ions in a redesigned proportional counter will provide greater discriminating power. The new active gas target design will be presented, and its simulated performance will be compared with test data. The Array for Nuclear Astrophysics and Structure with Exotic Nuclei (ANASEN) is a charged particle detector array with an active gas target-detector capability for sensitive measurements using radioactive ion beams. One of the main goals is to improve our understanding of nuclear reactions important in stellar explosions. Following initial experimental campaigns with ANASEN, we have been developing an improved active gas target design for ANASEN that incorporates an innovative cylindrical gas ionization detector for heavy ions surrounding the beam axis inside of the other ANASEN charged particle detectors. The detection of heavy ions in coincidence with lighter ions in a redesigned proportional counter will provide greater discriminating power. The new active gas target design will be presented, and its simulated performance will be compared with test data. This work was supported by the U.S. National Science Foundation and the Dept of Energy's Office of Science.

  9. The subzero microbiome: microbial activity in frozen and thawing soils.

    PubMed

    Nikrad, Mrinalini P; Kerkhof, Lee J; Häggblom, Max M

    2016-06-01

    Most of the Earth's biosphere is characterized by low temperatures (<5°C) and cold-adapted microorganisms are widespread. These psychrophiles have evolved a complex range of adaptations of all cellular constituents to counteract the potentially deleterious effects of low kinetic energy environments and the freezing of water. Microbial life continues into the subzero temperature range, and this activity contributes to carbon and nitrogen flux in and out of ecosystems, ultimately affecting global processes. Microbial responses to climate warming and, in particular, thawing of frozen soils are not yet well understood, although the threat of microbial contribution to positive feedback of carbon flux is substantial. To date, several studies have examined microbial community dynamics in frozen soils and permafrost due to changing environmental conditions, and some have undertaken the complicated task of characterizing microbial functional groups and how their activity changes with changing conditions, either in situ or by isolating and characterizing macromolecules. With increasing temperature and wetter conditions microbial activity of key microbes and subsequent efflux of greenhouse gases also increase. In this review, we aim to provide an overview of microbial activity in seasonally frozen soils and permafrost. With a more detailed understanding of the microbiological activities in these vulnerable soil ecosystems, we can begin to predict and model future expectations for carbon release and climate change.

  10. Effects of plant species coexistence on soil enzyme activities and soil microbial community structure under Cd and Pb combined pollution.

    PubMed

    Gao, Yang; Zhou, Pei; Mao, Liang; Zhi, Yueer; Zhang, Chunhua; Shi, Wanjun

    2010-01-01

    The relationship between plant species coexistence and soil microbial communities under heavy metal pollution has attracted much attention in ecology. However, whether plant species coexistence could offset the impacts of heavy metal combined pollution on soil microbial community structure and soil enzymes activities is not well studied. The modified ecological dose model and PCR-RAPD method were used to assess the effects of two plant species coexistence on soil microbial community and enzymes activities subjected to Cd and Pb combined stress. The results indicated that monoculture and mixed culture would increased microbe populations under Cd and Pb combined stress, and the order of sensitivity of microbial community responding to heavy metal stress was: actinomycetes > bacteria > fungi. The respirations were significantly higher in planted soil than that in unplanted soil. The plant species coexistence could enhance soil enzyme activities under Cd and Pb combined. Furthermore, planted soil would be helpful to enhance soil genetic polymorphisms, but Cd and Pb pollution would cause a decrease on soil genetic polymorphisms. Mixed culture would increase the ecological dose 50% (EDs50) values, and the ED50 values for soil enzyme activities decreased with increasing culture time. The dehydrogenase was most sensitive to metal addition and easily loses activity under low dose of heavy metal. However, it was difficult to fully inhibit the phoshpatase activity, and urease responded similarly with phosphatase.

  11. Assessment of soil-gas and soil contamination at the South Prong Creek Disposal Area, Fort Gordon, Georgia, 2009-2010

    USGS Publications Warehouse

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

    2011-01-01

    Soil gas and soil were assessed for contaminants at the South Prong Creek Disposal Area at Fort Gordon, Georgia, from October 2009 to September 2010. The assessment included identifying and delineating organic contaminants present in soil-gas and inorganic contaminants present in soil samples collected from the area estimated to be the South Prong Creek Disposal Area, including two seeps and the hyporheic zone. This assessment was conducted to provide environmental contamination data to Fort Gordon personnel pursuant to requirements for the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. All soil-gas samplers in the two seeps and the hyporheic zone contained total petroleum hydrocarbons above the method detection level. The highest total petroleum hydrocarbon concentration detected from the two seeps was 54.23 micrograms per liter, and the highest concentration in the hyporheic zone was 344.41 micrograms per liter. The soil-gas samplers within the boundary of the South Prong Creek Disposal Area and along the unnamed road contained total petroleum hydrocarbon mass above the method detection level. The highest total petroleum hydrocarbon mass detected was 147.09 micrograms in a soil-gas sampler near the middle of the unnamed road that traverses the South Prong Creek Disposal Area. The highest undecane mass detected was 4.48 micrograms near the location of the highest total petroleum hydrocarbon mass. Some soil-gas samplers detected undecane mass greater than the method detection level of 0.04 micrograms, with the highest detection of toluene mass of 109.72 micrograms in the same location as the highest total petroleum hydrocarbon mass. Soil-gas samplers installed in areas of high contaminant mass had no detections of explosives and chemical agents above their respective method detection levels. Inorganic concentrations in five soil samples did not exceed regional screening levels established by the U.S. Environmental Protection Agency

  12. The Soil Moisture Active and Passive (SMAP) Mission

    NASA Technical Reports Server (NTRS)

    Entekhabi, Dara; Nijoku, Eni G.; ONeill, Peggy E.; Kellogg, Kent H.; Crow, Wade T.; Edelstein, Wendy N.; Entin, Jared K.; Goodman, Shawn D.; Jackson, Thomas J.; Johnson, Joel; Kimball, John; Piepmeier, Jeffrey R.; Koster, Randal D.; McDonald, Kyle C.; Moghaddam, Mahta; Moran, Susan; Reichle, Rolf; Shi, J. C.; Spencer, Michael W.; Thurman, Samuel W.; Tsang, Leung; VanZyl, Jakob

    2009-01-01

    The Soil Moisture Active and Passive (SMAP) Mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council s Decadal Survey. SMAP will make global measurements of the moisture present at Earth's land surface and will distinguish frozen from thawed land surfaces. Direct observations of soil moisture and freeze/thaw state from space will allow significantly improved estimates of water, energy and carbon transfers between land and atmosphere. Soil moisture measurements are also of great importance in assessing flooding and monitoring drought. SMAP observations can help mitigate these natural hazards, resulting in potentially great economic and social benefits. SMAP soil moisture and freeze/thaw timing observations will also reduce a major uncertainty in quantifying the global carbon balance by helping to resolve an apparent missing carbon sink on land over the boreal latitudes. The SMAP mission concept would utilize an L-band radar and radiometer. These instruments will share a rotating 6-meter mesh reflector antenna to provide high-resolution and high-accuracy global maps of soil moisture and freeze/thaw state every two to three days. The SMAP instruments provide direct measurements of surface conditions. In addition, the SMAP project will use these observations with advanced modeling and data assimilation to provide deeper root-zone soil moisture and estimates of land surface-atmosphere exchanges of water, energy and carbon. SMAP is scheduled for a 2014 launch date

  13. [Gas exchange features of Ambrosia artemisiifolia leaves and fruits and their correlations with soil heavy metals].

    PubMed

    Zu, Yuangang; Wang, Wenjie; Chen, Huafeng; Yang, Fengjian; Zhang, Zhonghua

    2006-12-01

    Ambrosia artemisiifolia can survive well in the habitats of heavy human disturbance and partial soil pollution. Weather its photosynthetic features benefit their survival is worthwhile to concern. With a refuse dump in Changchun City (43 degrees 50'N, 125 degrees 23'E) as study site, this paper analyzed the contents of soil Cu, Pb, Zn, Mn, Cr, Co, Ni, Cd, As, Sb and Hg at ten plots, and measured in situ the gas exchange in A. artemisiifolia leaves and young fruits. The results showed that the study site was slightly contaminated by Ni, but the contents of other soil heavy metals were approached to or substantially lower than their threshold values. The net photosynthetic rate of leaves ranged from 1.88 to 9.41 micromol x m(-2) x s(-1), while that of young fruits could be up to 2. 81 micromol x m(-2) s(-1). Averagely, the respiration rate, stomatal conductance, photosynthetic rate, and water utilization efficiency of leaves were 1.81 micromol x m(-2) x s(-1), 75.7 mmol x m(-2) x s(-1), 6.05 micromol x m(-2) x s(-1), and 4.72 micromol CO2 x mmol(-1) H2O, being 5.26, 0.64, 1.31 and 1.69 times as much as those of young fruits, respectively, indicating that the respiratory and photosynthetic capacities and water use efficiency of A. artemisiifolia young fruits were equivalent to or higher than those of its leaves. Many test heavy metals, such as Cu, Pb, Zn, Cd, As, Sb and Hg, had no significant effects on the gas exchange features of leaves and fruits, but there were significant correlations of Ni and Cr with the stomatal conductance and water use efficiency of leaves and young fruits, Cr with the gross photosynthesis of leaves, and As with the stomatal conductance of young fruits, suggesting that a majority of test soil heavy metals had no direct effects on the gas exchange in A. artemisiifolia leaves and fruits, but soil Ni, Cr and As with the contents approached to or substantially lower than the threshold values could affect the gas exchange features of A

  14. Ice Nucleation Activity of Various Agricultural Soil Dust Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Schiebel, Thea; Höhler, Kristina; Funk, Roger; Hill, Thomas C. J.; Levin, Ezra J. T.; Nadolny, Jens; Steinke, Isabelle; Suski, Kaitlyn J.; Ullrich, Romy; Wagner, Robert; Weber, Ines; DeMott, Paul J.; Möhler, Ottmar

    2016-04-01

    Recent investigations at the cloud simulation chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) suggest that agricultural soil dust has an ice nucleation ability that is enhanced up to a factor of 10 compared to desert dust, especially at temperatures above -26 °C (Steinke et al., in preparation for submission). This enhancement might be caused by the contribution of very ice-active biological particles. In addition, soil dust aerosol particles often contain a considerably higher amount of organic matter compared to desert dust particles. To test agricultural soil dust as a source of ice nucleating particles, especially for ice formation in warm clouds, we conducted a series of laboratory measurements with different soil dust samples to extend the existing AIDA dataset. The AIDA has a volume of 84 m3 and operates under atmospherically relevant conditions over wide ranges of temperature, pressure and humidity. By controlled adiabatic expansions, the ascent of an air parcel in the troposphere can be simulated. As a supplement to the AIDA facility, we use the INKA (Ice Nucleation Instrument of the KArlsruhe Institute of Technology) continuous flow diffusion chamber based on the design by Rogers (1988) to expose the sampled aerosol particles to a continuously increasing saturation ratio by keeping the aerosol temperature constant. For our experiments, soil dust was dry dispersed into the AIDA vessel. First, fast saturation ratio scans at different temperatures were performed with INKA, sampling soil dust aerosol particles directly from the AIDA vessel. Then, we conducted the AIDA expansion experiment starting at a preset temperature. The combination of these two different methods provides a robust data set on the temperature-dependent ice activity of various agriculture soil dust aerosol particles with a special focus on relatively high temperatures. In addition, to extend the data set, we investigated the role of biological and organic matter in more

  15. Evaluation of biological treatability of soil contaminated with manufactured gas plant waste

    SciTech Connect

    Ginn, J.S.; Sims, R.C.; Murarka, I.P.

    1995-12-31

    The biological treatability of subsurface soil contaminated with manufactured gas plant (MGP) waste was evaluated. Mineralization assays incorporating {sup 14}C-phenanthrene were used to evaluate the biotransformation potential of indigenous microorganisms at the site. Multi-phase laboratory microcosms were used to evaluate the interphase transfer potential and chemical mass distribution of phenanthrene mineralization was influenced by nutrient addition and by the amount of contamination. The chemical mass distribution of {sup 14}C-phenanthrene indicated that volatilization may be an important transport mechanism for chemicals residing in, or migrating to the vadose zone of soil. Following removal of the coal-tar waste source at the site, the toxicity of water soluble extracts of the site soil decreased to a non-toxic response based upon Microtox{trademark} assay results. Parent compound compound concentrations at the site also decreased with time subsequent to source removal. Results of this study indicate that natural in situ bioremediation may be an important treatment process at a former manufactured gas plant waste site in New York. 21 refs., 5 figs., 4 tabs.

  16. 222Rn and 220Rn concentrations in soil gas of Karkonosze-Izera Block (Sudetes, Poland).

    PubMed

    Malczewski, Dariusz; Zaba, Jerzy

    2007-01-01

    Soil gas 222Rn and 220Rn concentrations were measured at 18 locations in the Karkonosze-Izera Block area in southwestern Poland. Measurements were carried out in surface air and at sampling depths of 10, 40 and 80 cm. Surface air 222Rn concentrations ranged from 4 to 2160 Bq m(-3) and 220Rn ranged from 4 to 228 Bq m(-3). The concentrations for 10 and 40 cm varied from 142 Bq m(-3) to 801 kBq m(-3) and 102 Bq m(-3) to 64 kBq m(-3) for 222Rn and 220Rn, respectively. At 80 cm 222Rn concentrations ranged from 94 Bq m(-3) to >1 MBq m(-3). The 220Rn concentrations at 80 cm varied from 45 Bq m(-3) to 48 kBq m(-3). The concentration versus depth profiles for 222Rn differed for soils developed on fault zones, uranium deposits or both. Atmospheric air temperature and soil gas 222Rn and 220Rn were negatively correlated. At sampling sites with steep slopes, 220Rn concentrations decreased with depth.

  17. Soil, Water, and Greenhouse-gas Impacts of Alternative Biomass Cropping Systems

    NASA Astrophysics Data System (ADS)

    Schulte Moore, L. A.; Bach, E.; Cambardella, C.; Hargreaves, S.; Helmers, M.; Hofmockel, K.; Isenhart, T.; Kolka, R. K.; Ontl, T.; Welsh, W.; Williams, R.; Landscape Biomass Team

    2010-12-01

    Through the 2008 Energy Independence and Security Act and other state and federal mandates, the U.S. is embarking on an aggressive agenda to reduce dependency on fossil fuels. While grain-derived ethanol will be used to largely meet initial renewable fuels targets, advanced biofuels derived from lignocellulosic materials are expected to comprise a growing proportion of the renewable energy portfolio and provide a more sustainable solution. As part of our interdisciplinary research, we are assessing the environmental impacts of four lignocellulosic biomass cropping systems and comparing them to a conventional corn cropping system. This comparison is conducted using a randomized, replicated experiment initiated in fall 2008, which compares the five cropping systems across a toposequence (i.e., floodplain, toeslope, backslope, shoulder, summit). In addition to assessing herbaceous and woody biomass yields, we are evaluating the environmental performance of these systems through changes in water quality, greenhouse-gas emissions, and carbon pools. Initial results document baseline soil parameters, including the capacity of the soils to sequester carbon across the toposequence, and the impacts of landscape heterogeneity and cropping system on soil moisture and nitrate-nitrogen levels in the vadose zone. Additional results on greenhouse-gas emissions and carbon dynamics are forthcoming from this year’s field research. The fuller understanding of the environmental performance of these systems will help inform federal and state policies seeking to incentivize the development of a sustainable bioenergy industry.

  18. Effect of different mulch materials on the soil dehydrogenase activity (DHA) in an organic pepper crop

    NASA Astrophysics Data System (ADS)

    Moreno, Marta M.; Peco, Jesús; Campos, Juan; Villena, Jaime; González, Sara; Moreno, Carmen

    2016-04-01

    The use biodegradable materials (biopolymers of different composition and papers) as an alternative to conventional mulches has increased considerably during the last years mainly for environmental reason. In order to assess the effect of these materials on the soil microbial activity during the season of a pepper crop organically grown in Central Spain, the soil dehydrogenase activity (DHA) was measured in laboratory. The mulch materials tested were: 1) black polyethylene (PE, 15 μm); black biopolymers (15 μm): 2) Mater-Bi® (corn starch based), 3) Sphere 4® (potato starch based), 4) Sphere 6® (potato starch based), 5) Bioflex® (polylactic acid based), 6) Ecovio® (polylactic acid based), 7) Mimgreen® (black paper, 85 g/m2). A randomized complete block design with four replications was adopted. The crop was drip irrigated following the water demand of each treatment. Soil samples (5-10 cm depth) under the different mulches were taken at different dates (at the beginning of the crop cycle and at different dates throughout the crop season). Additionally, samples of bare soil in a manual weeding and in an untreated control were taken. The results obtained show the negative effect of black PE on the DHA activity, mainly as result of the higher temperature reached under the mulch and the reduction in the gas interchange between the soil and the atmosphere. The values corresponding to the biodegradable materials were variable, although highlighting the low DHA activity observed under Bioflex®. In general, the uncovered treatments showed higher values than those reached under mulches, especially in the untreated control. Keywords: mulch, biodegradable, biopolymer, paper, dehydrogenase activity (DHA). Acknowledgements: the research was funded by Project RTA2011-00104-C04-03 from the INIA (Spanish Ministry of Economy and Competitiveness).

  19. To what extent can zero tillage lead to a reduction in greenhouse gas emissions from temperate soils?

    PubMed Central

    Mangalassery, Shamsudheen; Sjögersten, Sofie; Sparkes, Debbie L.; Sturrock, Craig J.; Craigon, Jim; Mooney, Sacha J.

    2014-01-01

    Soil tillage practices have a profound influence on the physical properties of soil and the greenhouse gas (GHG) balance. However there have been very few integrated studies on the emission of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) and soil biophysical and chemical characteristics under different soil management systems. We recorded a significantly higher net global warming potential under conventional tillage systems (26–31% higher than zero tillage systems). Crucially the 3-D soil pore network, imaged using X-ray Computed Tomography, modified by tillage played a significant role in the flux of CO2 and CH4. In contrast, N2O flux was determined mainly by microbial biomass carbon and soil moisture content. Our work indicates that zero tillage could play a significant role in minimising emissions of GHGs from soils and contribute to efforts to mitigate against climate change. PMID:24699273

  20. Microbial activity and soil organic matter decay in roadside soils polluted with petroleum hydrocarbons

    NASA Astrophysics Data System (ADS)

    Mykhailova, Larysa; Fischer, Thomas; Iurchenko, Valentina

    2015-04-01

    positively correlated with the carbohydrate fraction and negatively correlated with the aliphatic fraction of the soil C, while carbohydrate-C and alkyl-C increased and decreased with distance from the road, respectively. It is proposed that petroleum hydrocarbons supress soil biological activity at concentrations above 1500 mg kg-1, and that soil organic matter priming primarily affects the carbohydrate fraction of soil organic matter. It can be concluded that the abundance of solid carbohydrates (O-alkyl C) is of paramount importance for the hydrocarbon mineralization under natural conditions, compared to more recalcitrant SOM fractions (mainly aromatic and alkyl C). References Mykhailova, L., Fischer, T., Iurchenko, V. (2013) Distribution and fractional composition of petroleum hydrocarbons in roadside soils. Applied and Environmental Soil Science, vol. 2013, Article ID 938703, 6 pages, DOI 10.1155/2013/938703 Mykhailova, L., Fischer, T., Iurchenko, V. (2014) Deposition of petroleum hydrocarbons with sediment trapped in snow in roadside areas. Journal of Environmental Engineering and Landscape Management 22(3):237-244, DOI 10.3846/16486897.2014.889698 Nelson P.N. and Baldock J.A. (2005) Estimating the molecular composition of a diverse range of natural organic materials from solid-state 13C NMR and elemental analyses, 2005, Biogeochemistry (2005) 72: 1-34, DOI 10.1007/s10533-004-0076-3 Zyakun, A., Nii-Annang, S., Franke, G., Fischer, T., Buegger, F., Dilly, O. (2011) Microbial Actvity and 13C/12C Ratio as Evidence of N-Hexadecane and N-Hexadecanoic Acid Biodegradation in Agricultural and Forest Soils. Geomicrobiology Journal 28:632-647, DOI 10.1080/01490451.2010.489922

  1. Biochar and hydrochar effects on greenhouse gas (carbon dioxide, nitrous oxide, and methane) fluxes from soils.

    PubMed

    Kammann, Claudia; Ratering, Stefan; Eckhard, Christian; Müller, Christoph

    2012-01-01

    With a growing world population and global warming, we are challenged to increase food production while reducing greenhouse gas (GHG) emissions. We studied the effects of biochar (BC) and hydrochar (HC) produced via pyrolysis or hydrothermal carbonization, respectively, on GHG fluxes in three laboratory incubation studies. In the first experiment, ryegrass was grown in sandy loam mixed with equal amounts of a nitrogen-rich peanut hull BC, compost, BC+compost, double compost, or no addition (control); wetting-drying cycles and N fertilization were applied. Biochar with or without compost significantly reduced NO emissions and did not change the CH uptake, whereas ryegrass yield was significantly increased. In the second experiment, 0% (control) or 8% (w/w) of BC (peanut hull, maize, wood chip, or charcoal) or 8% HC (beet chips or bark) was mixed into a soil and incubated at 65% water-holding capacity (WHC) for 140 d. Treatments included simulated plowing and N fertilization. All BCs reduced NO emissions by ∼60%. Hydrochars reduced NO emissions only initially but significantly increased them after N fertilization to 302% (HC-beet) and 155% (HC-bark) of the control emissions, respectively. Large HC-associated CO emissions suggested that microbial activity was stimulated and that HC was less stable than BC. In the third experiment, nutrient-rich peanut hull BC addition and incubation over 1.5 yr at high WHCs did not promote NO emissions. However, NO emissions were significantly increased with BC after NHNO addition. In conclusion, BC reduced NO emissions and improved the GHG-to-yield ratio under field-relevant conditions. However, the risk of increased NO emissions with HC addition must be carefully evaluated.

  2. Effect of Byproducts of Flue Gas Desulfurization on the Soluble Salts Composition and Chemical Properties of Sodic Soils

    PubMed Central

    Wang, Jinman; Bai, Zhongke; Yang, Peiling

    2013-01-01

    The byproducts of flue gas desulfurization (BFGD) are a useful external source of Ca2+ for the reclamation of sodic soils because they are comparatively cheap, generally available and have high gypsum content. The ion solution composition of sodic soils also plays an important role in the reclamation process. The effect of BFGD on the soluble salts composition and chemical properties of sodic soils were studied in a soil column experiment. The experiment consisted of four treatments using two different sodic soils (sodic soil I and sodic soil II) and two BFGD rates. After the application of BFGD and leaching, the soil soluble salts were transformed from sodic salts containing Na2CO3 and NaHCO3 to neutral salts containing NaCl and Na2SO4. The sodium adsorption ratio (SAR), pH and electrical conductivity (EC) decreased at all soil depths, and more significantly in the top soil depth. At a depth of 0–40 cm in both sodic soil I and sodic soil II, the SAR, EC and pH were less than 13, 4 dS m−1 and 8.5, respectively. The changes in the chemical properties of the sodic soils reflected the changes in the ion composition of soluble salts. Leaching played a key role in the reclamation process and the reclamation effect was positively associated with the amount of leaching. The soil salts did not accumulate in the top soil layer, but there was a slight increase in the middle and bottom soil depths. The results demonstrate that the reclamation of sodic soils using BFGD is promising. PMID:23936481

  3. Effect of byproducts of flue gas desulfurization on the soluble salts composition and chemical properties of sodic soils.

    PubMed

    Wang, Jinman; Bai, Zhongke; Yang, Peiling

    2013-01-01

    The byproducts of flue gas desulfurization (BFGD) are a useful external source of Ca(2+) for the reclamation of sodic soils because they are comparatively cheap, generally available and have high gypsum content. The ion solution composition of sodic soils also plays an important role in the reclamation process. The effect of BFGD on the soluble salts composition and chemical properties of sodic soils were studied in a soil column experiment. The experiment consisted of four treatments using two different sodic soils (sodic soil I and sodic soil II) and two BFGD rates. After the application of BFGD and leaching, the soil soluble salts were transformed from sodic salts containing Na2CO3 and NaHCO3 to neutral salts containing NaCl and Na2SO4. The sodium adsorption ratio (SAR), pH and electrical conductivity (EC) decreased at all soil depths, and more significantly in the top soil depth. At a depth of 0-40 cm in both sodic soil I and sodic soil II, the SAR, EC and pH were less than 13, 4 dS m(-1) and 8.5, respectively. The changes in the chemical properties of the sodic soils reflected the changes in the ion composition of soluble salts. Leaching played a key role in the reclamation process and the reclamation effect was positively associated with the amount of leaching. The soil salts did not accumulate in the top soil layer, but there was a slight increase in the middle and bottom soil depths. The results demonstrate that the reclamation of sodic soils using BFGD is promising.

  4. Continuous monitoring of soil gas efflux with Forced Diffusion (FD) chamber technique in a tundra ecosystem, Alaska

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Park, S. J.; Lee, B. Y.

    2015-12-01

    Continuous measurements of soil carbon dioxide (CO2) efflux provide essential information about the soil carbon budget in response to an abruptly changing climate at Arctic and Subarctic scales. The Forced Diffusion (FD) chamber technique has a gas permeable membrane, which passively regulates the mixing of atmosphere and soil air in the chamber, in place of the active pumping system inside a regular dynamics efflux chamber system (Risk et al., 2011). Here the system has been modified the sampling routine to eliminate the problem of sensor drift. After that, we deployed the FD chamber system in a tundra ecosystem over the discontinuous permafrost regime of Council, Alaska. The representative understory plants are tussock (17 %), lichen (32 %), and moss (51 %), within a 40 נ40 m plot at an interval of five meters (81 points total) for efflux-measurement by dynamic chamber. The FD chamber monitored soil CO2 efflux from moss, lichen, and tussock regimes at an interval of 30 min during the growing season of 2015. As the results, mean soil CO2 effluxes in sphagnum moss, lichen, and tussock were 1.98 ± 1.10 (coefficient of variance: 55.8 %), 3.34 ± 0.84 (CV: 25.0 %), and 5.32 ± 1.48 (CV: 27.8 %) gCO2/m2/d, respectively. The difference between the 30-min efflux interval and the average efflux of three 10-min intervals is not significant for sphagnum (n = 196), lichen (n = 918), and tussock (n = 918) under a 95 % confidence level. The deploying interval was then set to 30 min and synchronized with eddy covariance tower data. During the deployment period of 2015, soil CO2 efflux over moss, lichen, and tussock using the FD chamber system were 44 ± 24, 73 ± 18, and 117 ± 33 gCO2/m2/period, respectively. Using the dynamic chamber, mean ecosystem respiration (Re) ranges for moss, lichen, and tussock were 2.2-2.6, 1.8-2.0, and 3.3-3.6 gCO2/m2/d, respectively, during June and July of 2015. These techniques provide the representativeness of spatiotemporal variation of soil

  5. Vegetation, soil property and climatic controls over greenhouse gas fluxes in a blanket peatland hosting a wind farm

    NASA Astrophysics Data System (ADS)

    Armstrong, Alona; Waldron, Susan; Ostle, Nick; Whitaker, Jeanette

    2013-04-01

    Peatlands are important carbon (C) stores, with boreal and subarctic peatlands containing 15-30 % of the world soil carbon stock (Limpens et al., 2008). Research has demonstrated that greenhouse gas (GHG) fluxes in peatlands are influenced by vegetation, soil property and climatic variables, including plant functional type (PFT), water table height and temperature. In this paper we present data from Black Law Wind Farm, Scotland, where we examined the effect of a predicted wind turbine-induced microclimatic gradient and PFT on carbon dioxide (CO2) and methane (CH4) fluxes. Moreover, we determined the role of vegetation, soil property and climatic variables as predictors of the variation in CO2 and CH4 emissions. We measured CO2 and CH4 at 48 plots within Black Law Wind Farm at monthly intervals from May 2011 to April 2012. Four sampling sites were located along a predicted wind turbine-induced microclimatic gradient. At each site four blocks were established, each with plots in areas dominated by mosses, sedges and shrubs. Plant biomass and PFT (vegetation factors); soil moisture, water table height, peat depth, C content, nitrogen (N) content and C:N (soil properties); and soil temperature and photosynthetically active radiation (PAR) (climatic variables) were measured. Analysis of variance (ANOVA) models based on the microclimatic gradient site, PFT and season when measurements were made explained 58 %, 44 % and 49 % of the variation in ecosystem respiration, photosynthesis and CH4, respectively. Site, PFT, season and their interactions were all significant for respiration and photosynthesis (with the exception of the PFT*site interaction) but for CH4 only the main effects were significant. Parsimonious ANOVA models using the biotic, soil property and climatic explanatory data explained 62 %, 55 % and 49 % of the variation in respiration, photosynthesis and CH4, respectively. Published studies (Baidya Roy and Traiteur 2010; Zhou et al., 2012) and preliminary

  6. High greenhouse gas fluxes from grassland on histic gleysol along soil carbon and drainage gradients

    NASA Astrophysics Data System (ADS)

    Leiber-Sauheitl, K.; Fuß, R.; Voigt, C.; Freibauer, A.

    2013-07-01

    Drained organic soils are anthropogenic emission hotspots of greenhouse gases (GHGs). Most studies have focused on deep peat soils and on peats with high organic carbon content. In contrast, Histic gleysols are characterized by shallow peat layers, which are left over from peat cutting activities, or by peat mixed with mineral soil. It is unknown whether they emit less GHGs than deep Histosols when drained. We present the annual carbon and GHG balance of grasslands for six sites on nutrient-poor histic gleysols with a shallow (30 cm) histic horizon or mixed with mineral soil in Northern Germany (soil organic carbon concentration (Corg) from 9 to 52%). The net GHG balance, corrected for carbon export by harvest, was around 4 t CO2-C-eq. ha-1 yr-1 on soils with peat layer and little drainage (mean annual water table <20 cm below surface). The net GHG balance reached 7-9 t CO2-C-eq. ha-1 yr-1 on soils with peat layer and deeper drainage (mean annual water table >20 cm below surface) and on soils with sand mixed into the histic horizon, independent of water table level. GHG emissions from drained histic gleysols (i) were as high as those from deep histosols, (ii) linearly related to water table, (iii) but not affected by Corg content of the histic horizon. Ecosystem respiration (Reco) was linearly correlated with water table level even if it was below the histic horizon. The Reco : GPP ratio was 1.5 at all sites, so that we ruled out a major influence of the inter-site variability in vegetation composition on annual net ecosystem exchange (NEE). The IPCC definition of organic soils includes shallow histic topsoil, unlike most national and international definitions of histosols. Our study confirms that this broader definition is appropriate considering anthropogenic GHG emissions from drained organic soils. Countries currently apply soil maps in national GHG inventories which are likely not to include histic gleysols. The land area with GHG emission hotspots due to

  7. Variations in rn and CO2 Soil Gas Concentrations in Karabayir Eskisehir-Turkey and Their Correlations with Earthquakes

    NASA Astrophysics Data System (ADS)

    Yasin, Didem; Hilmi Gülbay, Ahmet; Yüce, Galip; Durgut, Aykut; Oruç, Cemal

    2016-04-01

    Variations in radon and CO2 gas concentrations of soil relations to earthquakes take attention of many researchers. The aim of this study is to monitor changes in soil radon and CO2 gas concentrations and to search possible anomalies originated from the seismicity in the vicinity of Eskisehir. Eskisehir is located between Aegean-Western Anatolian block where the extensional regime is present and the snistrial strike-slip fault zone, with a normal component, belonging to Central Anatolian Block on which the compressional forces are effective. Radon and CO2 gas concentrations in soil were daily measured for about 3 months in 2015. Meteorological parameters (barometric pressure, temperature, rain and humidity) and all soil gasdata were correlated with the seismicity occured in 17-110 km distance from the soil gas measurement location during the same period. According to the first results, generally concentrations of Rn and CO2 began to decrease before earthquakes and CO2 and radon concentrations are linear which means. CO2 can be considered as acarrier gas for radon. Keywords: radon, CO2, Eskisehir, earthquake, soil

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

    PubMed

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

    2011-05-01

    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.

  9. Hydrocarbon anomaly in soil gas as near-surface expressions of upflows and outflows in geothermal systems

    SciTech Connect

    Ong, H.L.; Higashihara, M.; Klusman, R.W.; Voorhees, K.J.; Pudjianto, R.; Ong, J

    1996-01-24

    A variety of hydrocarbons, C1 - C12, have been found in volcanic gases (fumarolic) and in geothermal waters and gases. The hydrocarbons are thought to have come from products of pyrolysis of kerogen in sedimentary rocks or they could be fed into the geothermal system by the recharging waters which may contain dissolved hydrocarbons or hydrocarbons extracted by the waters from the rocks. In the hot geothermal zone, 300°+ C, many of these hydrocarbons are in their critical state. It is thought that they move upwards due to buoyancy and flux up with the upflowing geothermal fluids in the upflow zones together with the magmatic gases. Permeability which could be provided by faults, fissures, mini and micro fractures are thought to provide pathways for the upward flux. A sensitive technique (Petrex) utilizing passive integrative adsorption of the hydrocarbons in soil gas on activated charcoal followed by desorption and analysis of the hydrocarbons by direct introduction mass spectrometry allows mapping of the anomalous areas. Surveys for geothermal resources conducted in Japan and in Indonesia show that the hydrocarbon anomaly occur over known fields and over areas strongly suspected of geothermal potential. The hydrocarbons found and identified were n-paraffins (C7-C9) and aromatics (C7-C8). Detection of permeable, i.e. active or open faults, parts of older faults which have been reactivated, e.g. by younger intersecting faults, and the area surrounding these faulted and permeable region is possible. The mechanism leading to the appearance of the hydrocarbon in the soil gas over upflow zones of the geothermal reservoir is proposed. The paraffins seems to be better pathfinders for the location of upflows than the aromatics. However the aromatics may, under certain circumstances, give better indications of the direction of the outflow of the geothermal system. It is thought that an upflow zone can be

  10. Gas Replacements for GFP to Track Microbial Dynamics in Soils and Sediments

    NASA Astrophysics Data System (ADS)

    Cheng, Hsiao-Ying; Silberg, Jonathan; Masiello, Caroline

    2016-04-01

    Metagenomic analyses offer unprecedented views of soil microbial communities, and additionally provide a host of testable hypotheses about the biological mechanisms driving global biogeochemical fluxes. Outside the biogeosciences, hypotheses generated by metagenomics are often tested using biosensors, microbes programmed to respond in a detectable way to either changes in their metabolism or changes in the environment. A very large number of microbial behaviors can be monitored using biosensors, but these sensors typically report in ways that are undetectable in soils, e.g. by releasing green fluorescent protein (GFP). We are building a new class of biosensors that report by releasing easily-detected gases. We will provide an overview of the potential uses of gas-reporting biosensors in geobiology, and will report the current development these sensors. One goal in the development of these sensors is to make tractable the testing of gene expression hypotheses derived from metagenomics data. Examples of processes that could be tracked non-invasively with gas sensors include coordination of biofilm formation, nitrification, rhizobial infection of plant roots, and at least some forms of methanogenesis, all of which are managed by the easily-engineered acyl homoserine lactone cell-cell communication system. Another relatively simple process to track with gas sensors is horizontal gene transfer. We will report on the progress of these proof-of-concept examples.

  11. The soil moisture active passive (SMAP) mission and validation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Soil Moisture Active Passive (SMAP) satellite will be launched by the National Aeronautics and Space Administration in October 2014. This satellite is the culmination of basic research and applications development over the past thirty years. During most of this period, research and development o...

  12. The Soil Moisture Active and Passive (SMAP) Mission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Soil Moisture Active and Passive (SMAP) Mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council’s Decadal Survey. SMAP will make global measurements of the moisture present at Earth's land surface and will distinguish frozen f...

  13. Aminocyclopyrachlor sorption in biochar and activated charcoal amended soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aminocyclopyrachlor is a new herbicide active ingredient, classified as a member of the new chemical class “pyrimidine carboxylic acids”. It is used for control of broadleaf weeds and brush on non-cropland. Due to its potential mobility in some soils, there is interest in whether aminocyclopyrachlor...

  14. Overview of the NASA soil moisture active/passive mission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The NASA Soil Moisture Active Passive (SMAP) Mission is currently in design Phase C and scheduled for launch in October 2014. Its mission concept is based on combined L-band radar and radiometry measurements obtained from a shared, rotating 6-meter antennae. These measurements will be used to retrie...

  15. DMS pulse and COS valley: the effect of simulated rainfall on sulfur gas exchange in dry soils of uncultivated marine terraces

    NASA Astrophysics Data System (ADS)

    Whelan, M.; Khan, M. H.; Barnash, K.; Vollering, J.; Rhew, R.

    2011-12-01

    Atmospheric sulfur compounds regulate climate by affecting cloud dynamics and reducing the amount of solar radiation that reaches the Earth's surface. Quantifying the terrestrial-atmosphere exchanges of sulfur has been challenging as only some of the controlling factors are known. In general, oxic soils are observed to act as a sink of reduced sulfur compounds (RSCs), while anoxic soils tend to act a source. Changes in soil moisture are therefore expected to greatly influence the direction of net gas fluxes of RSCs. Here we report the effect of simulated rainfall on soil samples from uncultivated marine terraces near Santa Cruz, CA, U.S.A (37.0°N, 122°W). Soils were collected in the dry season of a Mediterranean-type climate and air dried before the analysis. The rate of production of dimethyl sulfide (DMS), a compound known to be produced by phytoplankton and bacteria, increased dramatically in the first hours after water addition, tapering off over a few days. A concurrent pulse in microbial respiration (as CO_2) was observed. Soils that experience lengthy dry periods, such as those from arid and Mediterranean climates, have been shown to exhibit increases of carbon mineralization after rain events due to a combination of released soil organic matter and increased microbial activity. Conversely, production of carbonyl sulfide (COS), the most abundant reduced sulfur compound in the atmosphere, decreased immediately upon wetting the soil, perhaps due to isolation of the soil atmosphere from the headspace by water. These simultaneous processes after the addition of water can transform a soil in the bulk oxic state into a net source of RSCs in a relatively short span of time.

  16. Influence of Environmental Factors on Feammox Activity in Soil Environments

    NASA Astrophysics Data System (ADS)

    Huang, S.; Jaffe, P. R.

    2015-12-01

    The oxidation of ammonium (NH4+) under iron reducing conditions, referred to as Feammox, has been described in recent years by several investigators. The environmental characteristics in which the Feammox process occurs need to be understood in order to determine its contribution to the nitrogen cycle. In this study, a total of 66 locations were selected covering 4 different types of soils/sediments: wetland soils (W), river sediments (R), forest soils (F), and paddy soils (P) from several locations in central New Jersey, at Tims Branch at Savannah River in South Carolina, both in the Unities States, and at several locations in the Guangdong province in China. Though soil chemical analyses, serial culturing experiments, analysis of microbial communities, and using a canonical correspondence analysis, the occurrence of the Feammox reaction and the presence of Acidimicrobiaceae bacterium A6, which plays a key role in the Feammox process(1), were found in 17 samples. Analyses showed that the soil pH, as well as its Fe(III) and NH4+ content were the most important factors controlling the distribution of these Feammox microorganisms. Based on the results, soils in the subtropical forests and soils that are near agricultural areas could be Feammox hotspot. Under the conditions that favor the presence and activity of Feammox microorganisms and their oxidation of NH4+, denitrification bacteria were also active. However, the presence of nitrous oxide (N2O) reducers was limited under these conditions, implying that at locations where the Feammox process is active, conditions are favoring a higher ratio of N2O: N2 as the nitrogen (N) end products. Incubations of soils where the presence of Acidimicrobiaceae bacterium A6 was detected, were conducted for 120 days under two different DO levels (DO < 0.02 mg/L and DO = 0.8~1.0 mg/L) showing comparable amounts of NH4+ oxidation. In the incubations with DO < 0.02 mg/L, the proportion of Acidimicrobiaceae bacteria increased and

  17. Seasonal Dynamics of Enzymatic Activities and Functional Diversity in Soils under Different Organic Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil microbial activity and diversity fluctuate seasonally under annual organic amendment for improving soil quality. We investigated the effects of municipal compost (MC), poultry litter (PL), and cover crops of spring oats and red clover (RC) on soil enzyme activities, and soil bacterial community...

  18. Effect of wastewater discharge on greenhouse gas fluxes from mangrove soils

    NASA Astrophysics Data System (ADS)

    Chen, G. C.; Tam, N. F. Y.; Wong, Y. S.; Ye, Y.

    2011-02-01

    The effects of wastewater on atmospheric fluxes of three greenhouse gases, nitrous oxide (N 2O), methane (CH 4) and carbon dioxide (CO 2) from mangrove soils were investigated, and the differences among shrimp pond wastewater (SP), livestock wastewater (LS) and municipal (S) sewage were compared. The gas emissions from mangrove soils were significantly enhanced after wastewater irrigation and the highest emission of N 2O and CO 2 were obtained from SP. High N 2O emission was also found in S treatment, where fluxes varied from 13.42 to 16.78 μmol m -2 h -1, but the CH 4 and CO 2 fluxes were as low as the control irrigated with tap water. Results of soil analyses indicated that the high N 2O emissions from mangrove soils receiving SP and S treatments were attributed to the denitrification and nitrification processes, respectively. The highest CH 4 flux was recorded in LS treatment (186.14-762.40 μmol m -2 h -1), which also had the highest CO 2 flux. The fluxes measured during the non-irrigation period were lower than those measured 4 h after irrigation.

  19. Flue gas desulfurization by-products additions to acid soil: alfalfa productivity and environmental quality.

    PubMed

    Chen, L; Dick, W A; Nelson, S

    2001-01-01

    Flue gas desulfurization (FGD) by-products are created when coal is burned and SO2 is removed from the flue gases. These FGD by-products are often alkaline and contain many plant nutrients. Land application of FGD by-products is encouraged but little information is available related to plant responses and environmental impacts concerning such use. Agricultural lime (ag-lime) and several new types of FGD by-products which contain either vermiculite or perlite were applied at 0, 0.5, 1.0, and 2.0 times the soil's lime requirement (LR) rate to an acidic soil (Wooster silt loam). The highest FGD by-products application rate was equivalent to 75.2 Mg ha(-1). Growth of alfalfa (Medicago sativa L.) was significantly increased compared to the untreated control in the second year after treatment with yields for the 1 x LR rate of FGD approximately 7-8 times greater compared to the untreated control and 30% greater than for the commercial ag-lime. Concentrations of Mo in alfalfa were significantly increased by FGD by-products application, compared to the untreated control, while compared to the ag-lime treatment, concentrations of B increased and Ba decreased. No soil contamination problems were observed, even at the 2xLR rate, indicating these materials can be safely applied to agricultural soils.

  20. Remediation of manufactured gas plant soils contaminated with free and complex cyanide

    SciTech Connect

    Maka, A.; Aronstein, B.N.; Srivastava, V.J.; Theis, T.L.; Young, T.C.

    1992-12-31

    Cyanide is one of the main contaminants present in soil from manufactured gas plants (MGP) . Several treatment methods including thermal treatment, chemical treatment, ultraviolet irradiation, and biological treatment were evaluated for their ability to degrade the cyanide present in these soils. In the thermal treatment, raising the temperature of the purified waste to 2000--3000C resulted in complete removal of complex cyanide from the soil; however, the cyanide emitted was in a the toxic gaseous HCN form. Chemical treatment, using the oxidant Fenton`s reagent in a 10% soil slurry, resulted in the destruction of 80% of the free cyanide but little, if any, complex cyanide. Ultraviolet irradiation of the basic leachate from MGP wastes in the presence of the chelating agent EDTA yielded 90% degradation of the complex cyanide. For biological treatment, using an aerobic mixed culture, almost 60% of the free cyanide disappeared from the system with minimal degradation of the complex cyanide. Each treatment has its limitations. Thus, a combined physical-chemical-biological treatment in which the complex cyanide is degraded to free cyanide by photodegradation under alkaline conditions, the free cyanide then chemically (by Fenton`s reagent) or biologically converted to NH{sub 3} and CO{sub 2}, is proposed for the removal of cyanide from MGP sites.

  1. Profiling of soil fatty acids using comprehensive two-dimensional gas chromatography with mass spectrometry detection.

    PubMed

    Zeng, Annie Xu; Chin, Sung-Tong; Patti, Antonio; Marriott, Philip J

    2013-11-22

    Profiling of phospholipid fatty acids (PLFA) represents a challenging goal for distinguishing the diversity of microbial communities and biomass in the complex and heterogeneous soil ecosystem. Comprehensive two-dimensional gas chromatography (GC×GC) coupled with simultaneous flame ionisation and mass spectrometry detection was applied as a culture-independent method for PLFA profiling of microbial classification in forest soil. A number of column sets were evaluated for the GC×GC separation of fatty acid methyl esters (FAME). Due to better isomeric separation and compound patterns on the 2D contour plot, an apolar-polar column combination was selected for soil microbial PLFA characterisation. A comprehensive view of PLFA composition with carbon chain length varying from 12 to 20 was observed in forest soil samples, with the commonly reported bacterial FAME of iso-/anteiso-, methyl-branched-, cyclopropyl-, and hydroxyl-substituted FA identified by their mass spectral and retention time according to authentic standards. Notably, some uncommon oxygenated FAME were found in high abundance and were further characterised by GC×GC coupled with high resolution mass spectrometry. This tentatively revealed geometric pairs of methyl 9,10-epoxyoctadecanoate isomers.

  2. [Determination of 13C enrichment in soil amino acid enantiomers by gas chromatogram/mass spectrometry].

    PubMed

    He, Hong-Bo; Zhang, Wei; Ding, Xue-Li; Bai, Zhen; Liu, Ning; Zhang, Xu-Dong

    2008-06-01

    The transformation and renewal of amino acid enantiomers is of significance in indicating the turnover mechanism of soil organic matter. In this paper, a method of gas chromatogram/mass spectrometry combined with U-13 C-glucose incubation was developed to determine the 13C enrichment in soil amino acid enantiomers, which could effectively differentiate the original and the newly synthesized amino acids in soil matrix. The added U-13 C-glucose was utilized rapidly to structure the amino acid carbon skeleton, and the change of relative abundance of isotope ions could be determined by mass spectrometry. The direct incorporation of U-13 C glucose was estimated by the intensity increase of m/z (F + n) to F (F was parent fragment, and n was the carbon number in the fragment), while the total isotope incorporation from the added 13C could be calculated according to the abundance ratio increment summation from m/z (Fa + 1) through (Fa + T) (Fa was the fragment containing all original skeleton carbons, and T was the carbon number in the amino acid molecule). The 13C enrichment in the target compound was expressed as atom percentage excess (APE), and that of D-amino acid needed to be corrected by the coefficient of hydrolysis-induced racemization. The 13C enrichment reflected the carbon turnover velocity of individual amino acid enantiomers, and was powerful to investigate the dynamics of soil amino acids.

  3. Amazing Soil Stories: Adventure and Activity Book [and] Teacher's Guide to the Activity Book.

    ERIC Educational Resources Information Center

    California Association of Resource Conservation Districts, Sacramento.

    The student activity book offers a variety of written exercises and "hands on" experiments and demonstrations for students at the fourth grade level. The book begins with a cartoon story that follows the adventures of a student investigating a soil erosion crisis and what her community can do to prevent soil erosion. Interspersed within…

  4. [Effects of simulated warming on soil enzyme activities in two subalpine coniferous forests in west Sichuan].

    PubMed

    Xu, Zhen-feng; Tang, Zheng; Wan, Chuan; Xiong, Pei; Cao, Gang; Liu, Qing

    2010-11-01

    With open top chamber (OTC), this paper studied the effects of simulated warming on the activities of soil invertase, urease, catalase, polyphenol oxidase in two contrasting subalpine coniferous forests (a dragon spruce plantation and a natural conifer forest) in west Sichuan. The dynamic changes of soil temperature and soil moisture were monitored synchronously. In the whole growth season, simulated warming enhanced the daily mean temperature at soil depth 5 cm by 0.61 degrees C in the plantation, and by 0.55 degrees C in the natural forest. Conversely, the volumetric moisture at soil depth 10 cm was declined by 4.10% and 2.55%, respectively. Simulated warming also increased soil invertase, urease, catalase, and polyphenol oxidase activities. The interactive effect of warming and forest type was significant on soil urease and catalase, but not significant on soil invertase and polyphenol oxidase. The warming effect on soil catalase depended, to some extent, on season change. In all treatments, the soil enzyme activities in the natural forest were significantly higher than those in the plantation. The seasonal changes of test soil enzyme activities were highly correlated with soil temperature, but less correlated with soil moisture. This study indicated that warming could enhance soil enzyme activities, and the effect had definite correlations with forest type, enzyme category, and season change. The soil enzyme activities in the subalpine coniferous forests were mainly controlled by soil temperature rather than soil moisture.

  5. Effects of Irrigating with Treated Oil and Gas Product Water on Crop Biomass and Soil Permeability

    SciTech Connect

    Terry Brown; Jeffrey Morris; Patrick Richards; Joel Mason

    2010-09-30

    Demonstrating effective treatment technologies and beneficial uses for oil and gas produced water is essential for producers who must meet environmental standards and deal with high costs associated with produced water management. Proven, effective produced-water treatment technologies coupled with comprehensive data regarding blending ratios for productive long-term irrigation will improve the state-of-knowledge surrounding produced-water management. Effective produced-water management scenarios such as cost-effective treatment and irrigation will discourage discharge practices that result in legal battles between stakeholder entities. The goal of this work is to determine the optimal blending ratio required for irrigating crops with CBNG and conventional oil and gas produced water treated by ion exchange (IX), reverse osmosis (RO), or electro-dialysis reversal (EDR) in order to maintain the long term physical integrity of soils and to achieve normal crop production. The soils treated with CBNG produced water were characterized with significantly lower SAR values compared to those impacted with conventional oil and gas produced water. The CBNG produced water treated with RO at the 100% treatment level was significantly different from the untreated produced water, while the 25%, 50% and 75% water treatment levels were not significantly different from the untreated water. Conventional oil and gas produced water treated with EDR and RO showed comparable SAR results for the water treatment technologies. There was no significant difference between the 100% treated produced water and the control (river water). The EDR water treatment resulted with differences at each level of treatment, which were similar to RO treated conventional oil and gas water. The 100% treated water had SAR values significantly lower than the 75% and 50% treatments, which were similar (not significantly different). The results of the greenhouse irrigation study found the differences in biomass

  6. Soils Activity Mobility Study: Methodology and Application

    SciTech Connect

    None, None

    2014-09-29

    This report presents a three-level approach for estimation of sediment transport to provide an assessment of potential erosion risk for sites at the Nevada National Security Site (NNSS) that are posted for radiological purposes and where migration is suspected or known to occur due to storm runoff. Based on the assessed risk, the appropriate level of effort can be determined for analysis of radiological surveys, field experiments to quantify erosion and transport rates, and long-term monitoring. The method is demonstrated at contaminated sites, including Plutonium Valley, Shasta, Smoky, and T-1. The Pacific Southwest Interagency Committee (PSIAC) procedure is selected as the Level 1 analysis tool. The PSIAC method provides an estimation of the total annual sediment yield based on factors derived from the climatic and physical characteristics of a watershed. If the results indicate low risk, then further analysis is not warranted. If the Level 1 analysis indicates high risk or is deemed uncertain, a Level 2 analysis using the Modified Universal Soil Loss Equation (MUSLE) is proposed. In addition, if a sediment yield for a storm event rather than an annual sediment yield is needed, then the proposed Level 2 analysis should be performed. MUSLE only provides sheet and rill erosion estimates. The U.S. Army Corps of Engineers Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) provides storm peak runoff rate and storm volumes, the inputs necessary for MUSLE. Channel Sediment Transport (CHAN-SED) I and II models are proposed for estimating sediment deposition or erosion in a channel reach from a storm event. These models require storm hydrograph associated sediment concentration and bed load particle size distribution data. When the Level 2 analysis indicates high risk for sediment yield and associated contaminant migration or when there is high uncertainty in the Level 2 results, the sites can be further evaluated with a Level 3 analysis using more complex

  7. In-situ soil composition and moisture measurement by surface neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Waring, C.; Smith, C.; Marks, A.

    2009-04-01

    Neutron activation analysis is widely known as a laboratory technique dependent upon a nuclear reactor to provide the neutron flux and capable of precise elemental analysis. Less well known in-situ geochemical analysis is possible with isotopic (252Cf & 241Am) or compact accelerator (D-T, D-D fusion reaction) neutron sources. Prompt gamma neutron activation analysis (PGNAA) geophysical borehole logging has been applied to mining issues for >15 years (CSIRO) using isotopic neutron sources and more recently to environmental and hydro-geological applications by ANSTO. Similarly, sophisticated geophysical borehole logging equipment based on inelastic neutron scattering (INS) has been applied in the oil and gas industry by large oilfield services companies to measure oil saturation indices (carbon/oxygen) using accelerator neutron sources. Recent advances in scintillation detector spectral performance has enabled improved precision and detection limits for elements likely to be present in soil profiles (H, Si, Al, Fe, Cl) and possible detection of many minor to trace elements if sufficiently abundant (Na, K, Mg, Ca, S, N, + ). To measure carbon an accelerator neutron source is required to provide fast neutrons above 4.8 MeV. CSIRO and ANSTO propose building a soil geochemical analysis system based on experience gained from building and applying PGNA borehole logging equipment. A soil geochemical analysis system could effectively map the 2D geochemical composition of the top 50cm of soil by dragging the 1D logging equipment across the ground surface. Substituting an isotopic neutron source for a D-T accelerator neutron source would enable the additional measurement of elemental carbon. Many potential ambiguities with other geophysical proxies for soil moisture may be resolved by direct geochemical measurement of H. Many other applications may be possible including time series in-situ measurements of soil moisture for differential drainage, hydrology, land surface

  8. County-Scale Spatial Distribution of Soil Enzyme Activities and Enzyme Activity Indices in Agricultural Land: Implications for Soil Quality Assessment

    PubMed Central

    Xie, Baoni; Wang, Junxing; He, Wenxiang; Wang, Xudong; Wei, Gehong

    2014-01-01

    Here the spatial distribution of soil enzymatic properties in agricultural land was evaluated on a county-wide (567 km2) scale in Changwu, Shaanxi Province, China. The spatial variations in activities of five hydrolytic enzymes were examined using geostatistical methods. The relationships between soil enzyme activities and other soil properties were evaluated using both an integrated total enzyme activity index (TEI) and the geometric mean of enzyme activities (GME). At the county scale, soil invertase, phosphatase, and catalase activities were moderately spatially correlated, whereas urease and dehydrogenase activities were weakly spatially correlated. Correlation analysis showed that both TEI and GME were better correlated with selected soil physicochemical properties than single enzyme activities. Multivariate regression analysis showed that soil OM content had the strongest positive effect while soil pH had a negative effect on the two enzyme activity indices. In addition, total phosphorous content had a positive effect on TEI and GME in orchard soils, whereas alkali-hydrolyzable nitrogen and available potassium contents, respectively, had negative and positive effects on these two enzyme indices in cropland soils. The results indicate that land use changes strongly affect soil enzyme activities in agricultural land, where TEI provides a sensitive biological indicator for soil quality. PMID:25610908

  9. Finger printing of mixed contaminants from former manufactured gas plant (MGP) site soils: Implications to bioremediation.

    PubMed

    Thavamani, Palanisami; Megharaj, Mallavarapu; Krishnamurti, G S R; McFarland, Ross; Naidu, Ravi

    2011-01-01

    Contaminants in general do not occur as single chemicals but as mixtures at any contaminated site. Gasworks sites are the typical mixed contaminated sites. These sites are not only subjected to PAH contamination but also varying degrees of heavy metal contamination. Bioremediation in these sites is often hindered by the presence of heavy metals. The co-occurrence of PAHs with heavy metals has not been systematically investigated. Metals are reported to inhibit the general soil microbiological processes. The total concentration of soluble metal in the system includes both free metal ion and complexed forms. Within bioavailable fraction, the most toxic form is the free metal species, which was not addressed well so far in gas works site characterisation. This study underpins the science and importance of metal bioavailability and speciation based site characterisation in mixed contaminated sites. In this study a detailed elemental chemistry of the gas works site soils are discussed using different methods. The PAH contamination was contributed by both low and high molecular weight PAHs. The total PAHs concentration ranged from 335 to 8645 mg/kg. Among most toxic metals Pb was found in high concentration ranging from 88 to 671 mg/kg, Cd 8 to 112 mg/kg and Zn varied from 64 to 488 mg/kg. Thermodynamic chemical equilibrium model VMINTEQ (Ver 2.52) was used to calculate the free metal species in gas works site soils. The percentage free metal species showed a different trend compared to total metal concentrations, free Zn species ranged 18-86%, free Cd was 26-87% and Pb showed lowest free metal percentage (0-17%). The bioavailable metal species and its implications to bioremediation have also been discussed.

  10. Soil radium, soil gas radon and indoor radon empirical relationships to assist in post-closure impact assessment related to near-surface radioactive waste disposal.

    PubMed

    Appleton, J D; Cave, M R; Miles, J C H; Sumerling, T J

    2011-03-01

    Least squares (LS), Theil's (TS) and weighted total least squares (WTLS) regression analysis methods are used to develop empirical relationships between radium in the ground, radon in soil and radon in dwellings to assist in the post-closure assessment of indoor radon related to near-surface radioactive waste disposal at the Low Level Waste Repository in England. The data sets used are (i) estimated ²²⁶Ra in the < 2 mm fraction of topsoils (eRa226) derived from equivalent uranium (eU) from airborne gamma spectrometry data, (ii) eRa226 derived from measurements of uranium in soil geochemical samples, (iii) soil gas radon and (iv) indoor radon data. For models comparing indoor radon and (i) eRa226 derived from airborne eU data and (ii) soil gas radon data, some of the geological groupings have significant slopes. For these groupings there is reasonable agreement in slope and intercept between the three regression analysis methods (LS, TS and WTLS). Relationships between radon in dwellings and radium in the ground or radon in soil differ depending on the characteristics of the underlying geological units, with more permeable units having steeper slopes and higher indoor radon concentrations for a given radium or soil gas radon concentration in the ground. The regression models comparing indoor radon with soil gas radon have intercepts close to 5 Bq m⁻³ whilst the intercepts for those comparing indoor radon with eRa226 from airborne eU vary from about 20 Bq m⁻³ for a moderately permeable geological unit to about 40 Bq m⁻³ for highly permeable limestone, implying unrealistically high contributions to indoor radon from sources other than the ground. An intercept value of 5 Bq m⁻³ is assumed as an appropriate mean value for the UK for sources of indoor radon other than radon from the ground, based on examination of UK data. Comparison with published data used to derive an average indoor radon: soil ²²⁶Ra ratio shows that whereas the published data are

  11. Gas and Chemical Activation of Charcoal

    DTIC Science & Technology

    1945-06-29

    supplemented ’ by runs in the laboratory has shown that zinc chloride is by far the most suitable activating agent. 1. In the dehydration mixing of...istics with time of dehydration . 3. The physical appearance of the mixture during the impregnation pperation provides sufficient significant information...to enable the operator to predict .mechanical characteristics of the briquet. CONFIDENTIAL " • ’< i£: • CONFIDENTIAL -4- 4* In the dehydration

  12. Ice nucleation activity in the widespread soil fungus Mortierella alpina

    NASA Astrophysics Data System (ADS)

    Fröhlich-Nowoisky, Janine; Hill, Thomas C. J.; Pummer, Bernhard G.; Yordanova, Petya; Franc, Gary D.; Pöschl, Ulrich

    2015-04-01

    Biological residues in soil dust are a potentially strong source of atmospheric ice nucleators (IN). However, the sources and characteristics of biological - in particular, fungal - IN in soil dust have not been characterized. By analysis of the culturable fungi in topsoils, from a range of different land use and ecosystem types in south-east Wyoming, we found ice nucleation active (INA, i.e., inducing ice formation in the probed range of temperature and concentration) fungi to be both widespread and abundant, particularly in soils with recent inputs of decomposable organic matter. For example, in harvested and ploughed sugar beet and potato fields, and in the organic horizon beneath Lodgepole pine forest, their relative abundances and concentrations among the cultivable fungi were 25% (8 x 103 CFU g-1), 17% (4.8 x 103 CFU g-1) and 17% (4 x 103 CFU g-1), respectively. Across all investigated soils, 8% (2.9 x 103 CFU g-1) of fungal isolates were INA. All INA isolates initiated freezing at -5° C to -6° C and all belonged to a single zygomycotic species, Mortierella alpina (Mortierellales, Mortierellomycotina). By contrast, the handful of fungal species so far reported as INA all belong within the Ascomycota or Basidiomycota phyla. Mortierella alpina is known to be saprobic (utilizing non-living organic matter), widespread in soil and present in air and rain. Sequencing of the ITS region and the gene for γ-linolenic elongase revealed four distinct clades, affiliated to different soil types. The IN produced by M. alpina seem to be extracellular proteins of 100-300 kDa in size which are not anchored in the fungal cell wall. Ice nucleating fungal mycelium will ramify topsoils and probably also release cell-free IN into it. If these IN survive decomposition or are adsorbed onto mineral surfaces, these small cell-free IN might contribute to the as yet uncharacterized pool of atmospheric IN released by soils as dusts.

  13. Soil-gas survey at the solid waste landfill - Final Report

    SciTech Connect

    Evans, J.C.; Fruland, R.M.; Glover, D.W.; Veverka, C.

    1989-12-01

    A soil-gas survey to determine the lateral distribution of chlorinated hydrocarbon solvents in the vadose zone, and possibly ground water, was conducted at the Hanford Site Solid Waste Landfill. For a 2-year period, three trenches just inside the western perimeter of the landfill had received liquid discharges of both sewage and washwater, which contained solvents. Ground-water monitoring wells, installed a few months after liquid discharge had been discontinued, indicated very low levels (less than 10 ppb) of solvents exist in the ground water downgradient from the disposal trenches. 13 refs., 7 figs., 1 tab.

  14. Temperature response of denitrification rate and greenhouse gas production in agricultural river marginal wetland soils.

    PubMed

    Bonnett, S A F; Blackwell, M S A; Leah, R; Cook, V; O'Connor, M; Maltby, E

    2013-05-01

    Soils are predicted to exhibit significant feedback to global warming via the temperature response of greenhouse gas (GHG) production. However, the temperature response of hydromorphic wetland soils is complicated by confounding factors such as oxygen (O2 ), nitrate (NO3-) and soil carbon (C). We examined the effect of a temperature gradient (2-25 °C) on denitrification rates and net nitrous oxide (N2 O), methane (CH4 ) production and heterotrophic respiration in mineral (Eutric cambisol and Fluvisol) and organic (Histosol) soil types in a river marginal landscape of the Tamar catchment, Devon, UK, under non-flooded and flooded with enriched NO3- conditions. It was hypothesized that the temperature response is dependent on interactions with NO3--enriched flooding, and the physicochemical conditions of these soil types. Denitrification rate (mean, 746 ± 97.3 μg m(-2)  h(-1) ), net N2 O production (mean, 180 ± 26.6 μg m(-2)  h(-1) ) and net CH4 production (mean, 1065 ± 183 μg m(-2)  h(-1) ) were highest in the organic Histosol, with higher organic matter, ammonium and moisture, and lower NO3- concentrations. Heterotrophic respiration (mean, 127 ± 4.6 mg m(-2)  h(-1) ) was not significantly different between soil types and dominated total GHG (CO2 eq) production in all soil types. Generally, the temperature responses of denitrification rate and net N2 O production were exponential, whilst net CH4 production was unresponsive, possibly due to substrate limitation, and heterotrophic respiration was exponential but limited in summer at higher temperatures. Flooding with NO3- increased denitrification rate, net N2 O production and heterotrophic respiration, but a reduction in net CH4 production suggests inhibition of methanogenesis by NO3- or N2 O produced from denitrification. Implications for management and policy are that warming and flood events may promote microbial interactions in soil between distinct microbial communities and increase

  15. Effect of gas velocity and influent concentration on biofiltration of gasoline off-gas from soil vapor extraction.

    PubMed

    Namkoong, Wan; Park, Joon-Seok; VanderGheynst, Jean S

    2004-11-01

    This study was conducted to evaluate the effects of gas inlet concentration and velocity on the biofiltration of gasoline vapor. Gasoline vapor was treated using a compost biofilter operated in an upflow mode for about 3 months. The inlet concentration of gasoline total petroleum hydrocarbon (TPH) ranged from about 300 to 7000 mgm(-3) and gas was injected at velocities of 6 and 15 mh(-1) (empty bed residence time (EBRT)=10 and 4 min, respectively). The maximum elimination capacities of TPH at 6 and 15 mh(-1) found in this research were over 24 and 19 gm(-3) of filling material h(-1), respectively. TPH removal data was fit using a first-order kinetic relationship. In the low concentration range of 300-3000 mg m(-3), the first-order kinetic constants varied between about 0.10 and 0.29 min(-1) regardless of gas velocities. At TPH concentrations greater than 3000 mgm(-3), the first-order kinetic constants were about 0.09 and 0.07 min(-1) at gas velocities of 6 mh(-1) and 15 mh(-1), respectively. To evaluate microbial dynamics, dehydrogenase activity, CO2 generation and microbial species diversity were analyzed. Dehydrogenase activity could be used as an indicator of microbial activity. TPH removal corresponded well with CO2 evolution. The average CO2 recovery efficiency for the entire biofilter ranged between 60% and 70%. When the gas velocity was 6 mh(-1), most of the microbial activity and TPH removal occurred in the first quarter of the biofilter. However, when the gas velocity was 15 mh(-1), the entire column contributed to removal. Spatial and temporal variations in the biofilter microbial population were also observed. Nearly 60% of the colonies isolated from the compost media prior to biofiltration were Bacillus. After 90 days of biofiltration, the predominant species in the lower portion (0-50 cm) of the filter were Rhodococcus, while Pseudomonas and Acinetobacter dominated the upper portion (75-100 cm).

  16. [Effects of nitrogen addition on soil physico-chemical properties and enzyme activities in desertified steppe].

    PubMed

    Su, Jie-Qiong; Li, Xin-Rong; Bao, Jing-Ting

    2014-03-01

    To investigate the impacts of nitrogen (N) enrichment on soil physico-chemical property and soil enzyme activities in desert ecosystems, a field experiment by adding N at 0, 1.75, 3.5, 7, or 14 g N x m(-2) a(-1) was conducted in a temperate desert steppe in the southeastern fringe of the Tengger Desert. The results showed that N addition led to accumulations of total N, NO(3-)-N, NH(4+)-N, and available N in the upper soil (0-10 cm) and subsoil (10-20 cm), however, reductions in soil pH were observed, causing soil acidification to some extent. N addition pronouncedly inhibited soil enzyme activities, which were different among N addition levels, soil depths, and years, respectively. Soil enzyme activities were significantly correlated with the soil N level, soil pH, and soil moisture content, respectively.

  17. Thermal and Evolved Gas Analysis (TEGA) of hyperarid soils doped with microorganisms from the Atacama Desert in southern Peru (Pampas de la Joya): Implications for the Phoenix Mission

    NASA Astrophysics Data System (ADS)

    Valdivia-Silva, Julio E.; Navarro-Gonzalez, Rafael; McKay, Chris

    TEGA is one of several instruments on board of the Phoenix Lander that will perform differential scanning calorimetry and evolved gas analysis of soil samples and ice, collected from the surface and subsurface at a northern landing site on Mars. TEGA is a combination of a high-temperature furnace and a mass spectrometer that will be use to analyze samples delivered to instrument via a robotic arm. The samples will be heated at a programmed ramp rate up to 1000° C and the power required for heating will be carefully and continuously monitored (scanning calorimetry). The evolved gases generated during the process will be analyzed with the evolved-gas analyzer (a magnetic sector mass spectrometer) in order to determine the composition of gases released as a function of temperature. Our laboratory has developed a sample characterization method using a pyrolizer integrated to a quadrupole mass spectrometer to support the interpretations of TEGA data. Here we examine the thermal and evolved gas properties of six types of hyperarid soils from the Pampas de La Joya southern Peru, a possible analog to Mars, which has been previously enriched with microorganisms (Salmonella thypimurium, Micrococcus luteus, and Candida albicans) to investigate the effect of soil matrix over TEGA response. Between 20 to 40 mg of soil pre-treated to 500° C for 24 hours to remove traces of organics, was mixed with or without 5mg biomass lyophilized (dry weight). Additionally 20 mg of each one microorganism were analyzed. The samples were placed in the pyrolizer that reached 1200° C at 1 hour. The volatiles released were transferred to the MS using helium as a carrier gas. The quadrupole MS was ran in scan mode from 40-350m/z. As expected, there were significant differences in the evolved gas behaviors for microorganism samples with or without a soil matrix under similar heating conditions. In addition, samples belonging to the most arid environments had significant differences compared with

  18. Sample storage for soil enzyme activity and bacterial community profiles.

    PubMed

    Wallenius, K; Rita, H; Simpanen, S; Mikkonen, A; Niemi, R M

    2010-04-01

    Storage of samples is often an unavoidable step in environmental data collection, since available analytical capacity seldom permits immediate processing of large sample sets needed for representative data. In microbiological soil studies, sample pretreatments may have a strong influence on measurement results, and thus careful consideration is required in the selection of storage conditions. The aim of this study was to investigate the suitability of prolonged (up to 16 weeks) frozen or air-dried storage for divergent soil materials. The samples selected to this study were mineral soil (clay loam) from an agricultural field, humus from a pine forest and compost from a municipal sewage sludge composting field. The measured microbiological parameters included functional profiling with ten different hydrolysing enzyme activities determined by artificial fluorogenic substrates, and structural profiling with bacterial 16S rDNA community fingerprints by amplicon length heterogeneity analysis (LH-PCR). Storage of samples affected the observed fluorescence intensity of the enzyme assay's fluorophor standards dissolved in soil suspension. The impact was highly dependent on the soil matrix and storage method, making it important to use separate standardisation for each combination of matrix type, storage method and time. Freezing proved to be a better storage method than air-drying for all the matrices and enzyme activities studied. The effect of freezing on the enzyme activities was small (<20%) in clay loam and forest humus and moderate (generally 20-30%) in compost. The most dramatic decreases (>50%) in activity were observed in compost after air-drying. The bacterial LH-PCR community fingerprints were unaffected by frozen storage in all matrices. The effect of storage treatments was tested using a new statistical method based on showing similarity rather than difference of results.

  19. 77 FR 58616 - Pipeline Safety: Information Collection Activities, Revision to Gas Transmission and Gathering...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-21

    ... Safety: Information Collection Activities, Revision to Gas Transmission and Gathering Pipeline Systems... TRANSPORTATION Pipeline and Hazardous Materials Safety Administration Pipeline Safety: Information Collection Activities, Revision to Gas Transmission and Gathering Pipeline Systems Annual Report, Gas Transmission...

  20. Soil organic matter dynamics under Beech and Hornbeam as affected by soil biological activity

    NASA Astrophysics Data System (ADS)

    Kooijman, A. M.; Cammeraat, L. H.

    2009-04-01

    Organic matter dynamics are highly affected both the soil fauna as well as the source of organic matter, having important consequences for the spatial heterogeneity of organic matter storage and conversion. We studied oldgrowth mixed deciduous forests in Central-Luxemburg on decalcified dolomitic marl, dominated by high-degradable hornbeam (Carpinus betulus L.) or low-degradable beech (Fagus sylvatica L.). Decomposition was measured both in the laboratory and in the field. Litter decomposition was higher for hornbeam than for beech under laboratory conditions, but especially in the field, which is mainly to be attributed to macro-fauna activity, specifically to earthworms (Lumbricus terrestris and Allolobophora species). We also investigated differences between beech and hornbeam with regard to litter input and habitat conditions. Total litter input was the same, but contribution of beech and hornbeam litter clearly differed between the two species. Also, mass of the ectorganic horizon and soil C:N ratio were significantly higher for beech, which was reflected in clear differences in the development of ectorganic profiles on top of the soil. Under beech a mull-moder was clearly present with a well developed fermentation and litter horizon, whereas under hornbeam all litter is incorporated into the soil, leaving the mineral soil surface bear in late summer (mull-type of horizon). In addition to litter quality, litter decomposition was affected by pH and soil moisture. Both pH and soil moisture were higher under hornbeam than under beech, which may reflect differences in soil development and litter quality effects over longer time scales. Under beech, dense layers of low-degradable litter may prevent erosion, and increase clay eluviation and leaching of base cations, leading to acid and dry conditions, which further decrease litter decay. Under hornbeam, the soil is not protected by a litter layer, and clay eluviation and acidification may be counteracted by erosion

  1. Assessing microbial activities in metal contaminated agricultural volcanic soils--An integrative approach.

    PubMed

    Parelho, C; Rodrigues, A S; Barreto, M C; Ferreira, N G C; Garcia, P

    2016-07-01

    Volcanic soils are unique naturally fertile resources, extensively used for agricultural purposes and with particular physicochemical properties that may result in accumulation of toxic substances, such as trace metals. Trace metal contaminated soils have significant effects on soil microbial activities and hence on soil quality. The aim of this study is to determine the soil microbial responses to metal contamination in volcanic soils under different agricultural land use practices (conventional, traditional and organic), based on a three-tier approach: Tier 1 - assess soil microbial activities, Tier 2 - link the microbial activity to soil trace metal contamination and, Tier 3 - integrate the microbial activity in an effect-based soil index (Integrative Biological Response) to score soil health status in metal contaminated agricultural soils. Our results showed that microbial biomass C levels and soil enzymes activities were decreased in all agricultural soils. Dehydrogenase and β-glucosidase activities, soil basal respiration and microbial biomass C were the most sensitive responses to trace metal soil contamination. The Integrative Biological Response value indicated that soil health was ranked as: organic>traditional>conventional, highlighting the importance of integrative biomarker-based strategies for the development of the trace metal "footprint" in Andosols.

  2. Microbial metabolic activity in soil as measured by dehydrogenase determinations

    NASA Technical Reports Server (NTRS)

    Casida, L. E., Jr.

    1977-01-01

    The dehydrogenase technique for measuring the metabolic activity of microorganisms in soil was modified to use a 6-h, 37 C incubation with either glucose or yeast extract as the electron-donating substrate. The rate of formazan production remained constant during this time interval, and cellular multiplication apparently did not occur. The technique was used to follow changes in the overall metabolic activities of microorganisms in soil undergoing incubation with a limiting concentration of added nutrient. The sequence of events was similar to that obtained by using the Warburg respirometer to measure O2 consumption. However, the major peaks of activity occurred earlier with the respirometer. This possibly is due to the lack of atmospheric CO2 during the O2 consumption measurements.

  3. Thermally evolved gas analysis (TEGA) of hyperarid soils doped with microorganisms from the Atacama Desert in southern Peru: Implications for the Phoenix mission

    NASA Astrophysics Data System (ADS)

    Valdivia-Silva, Julio E.; Navarro-González, Rafael; McKay, Christopher

    2009-07-01

    TEGA, one of several instruments on board of the Phoenix Lander, performed differential scanning calorimetry and evolved gas analysis of soil samples and ice, collected from the surface and subsurface at a northern landing site on Mars. TEGA is a combination of a high temperature furnace and a mass spectrometer (MS) that was used to analyze samples delivered to the instrument via a robotic arm. The samples were heated at a programmed ramp rate up to 1000 °C. The power required for heating can be carefully and continuously monitored (scanning calorimetry). The evolved gases generated during the process can be analyzed with the evolved gas analyzer (a magnetic sector mass spectrometer) in order to determine the composition of gases released as a function of temperature. Our laboratory has developed a sample characterization method using a pyrolyzer integrated to a quadrupole mass spectrometer to support the interpretations of TEGA data. Here we examine the evolved gas properties of six types of hyperarid soils from the Pampas de La Joya in southern Peru (a possible analog to Mars), to which we have added with microorganisms ( Salmonella typhimurium, Micrococcus luteus, and Candida albicans) in order to investigate the effect of the soil matrix on the TEGA response. Between 20 and 40 mg of soil, with or without ˜5 mg of lyophilized microorganism biomass (dry weight), were placed in the pyrolyzer and heated from room temperature to 1200 °C in 1 h at a heating rate of 20 °C/min. The volatiles released were transferred to a MS using helium as a carrier gas. The quadrupole MS was ran in scan mode from 10 to 200 m/z. In addition, ˜20 mg of each microorganism without a soil matrix were analyzed. As expected, there were significant differences in the gases released from microorganism samples with or without a soil matrix, under similar heating conditions. Furthermore, samples from the most arid environments had significant differences compared with less arid soils

  4. Measurements of Microbial Community Activities in Individual Soil Macroaggregates

    SciTech Connect

    Bailey, Vanessa L.; Bilskis, Christina L.; Fansler, Sarah J.; McCue, Lee Ann; Smith, Jeff L.; Konopka, Allan

    2012-05-01

    The functional potential of single soil aggregates may provide insights into the localized distribution of microbial activities better than traditional assays conducted on bulk quantities of soil. Thus, we scaled down enzyme assays for {beta}-glucosidase, N-acetyl-{beta}-D-glucosaminidase, lipase, and leucine aminopeptidase to measure of the enzyme potential of individual aggregates (250-1000 {mu}m diameter). Across all enzymes, the smallest aggregates had the greatest activity and the range of enzyme activities observed in all aggregates supports the hypothesis that functional potential in soil may be distributed in a patchy fashion. Paired analyses of ATP as a surrogate for active microbial biomass and {beta}-glucosidase on the same aggregates suggest the presence of both extracellular {beta}-glucosidase functioning in aggregates with no detectable ATP and also of relatively active microbial communities (high ATP) that have low {beta}-glucosidase potentials. Studying function at a scale more consistent with microbial habitat presents greater opportunity to link microbial community structure to microbial community function.

  5. Modification of soil microbial activity and several hydrolases in a forest soil artificially contaminated with copper

    NASA Astrophysics Data System (ADS)

    Bellas, Rosa; Leirós, Mā Carmen; Gil-Sotres, Fernando; Trasar-Cepeda, Carmen

    2010-05-01

    Soils have long been exposed to the adverse effects of human activities, which negatively affect soil biological activity. As a result of their functions and ubiquitous presence microorganisms can serve as environmental indicators of soil pollution. Some features of soil microorganisms, such as the microbial biomass size, respiration rate, and enzyme activity are often used as bioindicators of the ecotoxicity of heavy metals. Although copper is essential for microorganisms, excessive concentrations have a negative influence on processes mediated by microorganisms. In this study we measured the response of some microbial indicators to Cu pollution in a forest soil, with the aim of evaluating their potential for predicting Cu contamination. Samples of an Ah horizon from a forest soil under oakwood vegetation (Quercus robur L.) were contaminated in the laboratory with copper added at different doses (0, 120, 360, 1080 and 3240 mg kg-1) as CuCl2×2H2O. The soil samples were kept for 7 days at 25 °C and at a moisture content corresponding to the water holding capacity, and thereafter were analysed for carbon and nitrogen mineralization capacity, microbial biomass C, seed germination and root elongation tests, and for urease, phosphomonoesterase, catalase and ß-glucosidase activities. In addition, carbon mineralization kinetics were studied, by plotting the log of residual C against incubation time, and the metabolic coefficient, qCO2, was estimated. Both organic carbon and nitrogen mineralization were lower in polluted samples, with the greatest decrease observed in the sample contaminated with 1080 mg kg-1. In all samples carbon mineralization followed first order kinetics; the C mineralization constant was lower in contaminated than in uncontaminated samples and, in general, decreased with increasing doses of copper. Moreover, it appears that copper contamination not only reduced the N mineralization capacity, but also modified the N mineralization process, since in

  6. Greenhouse gas (CO2, CH4, N2O) emissions from soils following afforestation in central China

    NASA Astrophysics Data System (ADS)

    Dou, Xiaolin; Zhou, Wei; Zhang, Quanfa; Cheng, Xiaoli

    2016-02-01

    The effects of afforestation are of great importance for terrestrial carbon sequestration. However, the consequences of afforestation for greenhouse gas (GHG, CO2, CH4 and N2O) fluxes remain poorly quantified. We investigate the temporal variations in CO2, CH4 and N2O fluxes in afforested soils (implementing woodland and shrubland) and the adjacent uncultivated area in the Danjiangkou Reservoir area of central China. We examined the effects of soil factors [e.g. soil temperature, soil moisture, soil pH, soil organic carbon (SOC), soil organic nitrogen (SON)], litter exclusion and vegetation types on GHG fluxes. Our results revealed that afforestation lead to a higher average CO2 flux from soils by 63.96% and a higher N2O flux by 54.53% in the observed year. The peak CO2 and CH4 fluxes from afforested soils occurred in summer, while the peak N2O flux occurred in winter. Afforestation also enhanced CH4 flux from soil with the largest increase by 247.94% in woodland and by 188.18% in shrubland in spring compared with the open area. On average, surface litter exclusion reduced soil CO2 fluxes by 18.84% and N2O fluxes by 27.93% in the woodland. The surface litter exclusion did not significantly affect CH4 flux from the afforested soils. The CO2, CH4 and N2O fluxes from soils were strongly influenced by soil temperature, moisture and SOC content across seasons. The N2O flux was also strongly affected by SON content in our experimental field. Our results suggested that afforestation enhanced GHG fluxes from soils; however, the magnitude of the GHG fluxes should also be considered from various environmental conditions and vegetation types.

  7. Construction and testing of a simple and economical soil greenhouse gas automatic sampler

    USGS Publications Warehouse

    Ginting, D.; Arnold, S.L.; Arnold, N.S.; Tubbs, R.S.

    2007-01-01

    Quantification of soil greenhouse gas emissions requires considerable sampling to account for spatial and/or temporal variation. With manual sampling, additional personnel are often not available to sample multiple sites within a narrow time interval. The objectives were to construct an automatic gas sampler and to compare the accuracy and precision of automatic versus manual sampling. The automatic sampler was tested with carbon dioxide (CO2) fluxes that mimicked the range of CO2 fluxes during a typical corn-growing season in eastern Nebraska. Gas samples were drawn from the chamber at 0, 5, and 10 min manually and with the automatic sampler. The three samples drawn with the automatic sampler were transferred to pre-vacuumed vials after 1 h; thus the samples in syringe barrels stayed connected with the increasing CO2 concentration in the chamber. The automatic sampler sustains accuracy and precision in greenhouse gas sampling while improving time efficiency and reducing labor stress. Copyright ?? Taylor & Francis Group, LLC.

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

    USGS Publications Warehouse

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

    2011-01-01

    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

  9. NASA Soil Moisture Active Passive Mission Status and Science Performance

    NASA Technical Reports Server (NTRS)

    Yueh, Simon H.; Entekhabi, Dara; O'Neill, Peggy; Njoku, Eni; Entin, Jared K.

    2016-01-01

    The Soil Moisture Active Passive (SMAP) observatory was launched January 31, 2015, and its L-band radiometer and radar instruments became operational since mid-April 2015. The SMAP radiometer has been operating flawlessly, but the radar transmitter ceased operation on July 7. This paper provides a status summary of the calibration and validation of the SMAP instruments and the quality assessment of its soil moisture and freeze/thaw products. Since the loss of the radar in July, the SMAP project has been conducting two parallel activities to enhance the resolution of soil moisture products. One of them explores the Backus Gilbert optimum interpolation and de-convolution techniques based on the oversampling characteristics of the SMAP radiometer. The other investigates the disaggregation of the SMAP radiometer data using the European Space Agency's Sentinel-1 C-band synthetic radar data to obtain soil moisture products at about 1 to 3 kilometers resolution. In addition, SMAP's L-band data have found many new applications, including vegetation opacity, ocean surface salinity and hurricane ocean surface wind mapping. Highlights of these new applications will be provided.

  10. Effects of petroleum contamination on soil microbial numbers, metabolic activity and urease activity.

    PubMed

    Guo, Huan; Yao, Jun; Cai, Minmin; Qian, Yiguang; Guo, Yue; Richnow, Hans H; Blake, Ruth E; Doni, Serena; Ceccanti, Brunello

    2012-06-01

    The influence of petroleum contamination on soil microbial activities was investigated in 13 soil samples from sites around an injection water well (Iw-1, 2, 3, 4) (total petroleum hydrocarbons (TPH): 7.5-78 mg kg(-1)), an oil production well (Op-1, 2, 3, 4, 5) (TPH: 149-1110 mg kg(-1)), and an oil spill accident well (Os-1, 2, 3, 4) (TPH: 4500-34600 mg kg(-1)). The growth rate constant (μ) of glucose stimulated organisms, determined by microcalorimetry, was higher in Iw soil samples than in Op and Os samples. Total cultivable bacteria and fungi and urease activity also decreased with increasing concentration of TPH. Total heat produced demonstrated that TPH at concentrations less than about 1 g kg(-1) soil stimulated anaerobic respiration. A positive correlation between TPH and soil organic matter (OM) and stimulation of fungi-bacteria-urease at low TPH doses suggested that TPH is bound to soil OM and slowly metabolized in Iw soils during OM consumption. These methods can be used to evaluate the potential of polluted soils to carry out self-bioremediation by metabolizing TPH.

  11. COMPARISON OF GEOPROBE PRT AND AMS GVP SOIL-GAS SAMPLING SYSTEMS WITH DEDICATED VAPOR PROBES IN SANDY SOILS AT THE RAYMARK SUPERFUND SITE

    EPA Science Inventory

    A study was conducted near the Raymark Superfund Site in Stratford, Connecticut to compare results of soil-gas sampling using dedicated vapor probes, a truck-mounted direct-push technique - the Geoprobe Post-Run-Tubing (PRT) system, and a hand-held rotary hammer technique - the A...

  12. Characterization of trichloroethylene adsorption onto waste biocover soil in the presence of landfill gas.

    PubMed

    He, Ruo; Su, Yao; Kong, Jiaoyan

    2015-09-15

    Waste biocover soils (WBS) have been demonstrated to have great potential in mitigating trichloroethylene (TCE) emission from landfills, due to the relatively high TCE-degrading capacity. In this study, the characteristics of TCE adsorption on WBS in the presence of the major landfill gas components (i.e., CH4 and CO2) were investigated in soil microcosms. The adsorption isotherm of TCE onto WBS was fitted well with linear model within the TCE concentrations of 7000 ppmv. The adsorption capacity of TCE onto WBS was affected by temperature, soil moisture content and particle size, of which, temperature was the dominant factor. The adsorption capacity of TCE onto the experimental materials increased with the increasing organic matter content. A significantly positive correlation was observed between the adsorption capacity of TCE and the organic matter content of experimental materials that had relatively higher organic content (r = 0.988, P = 0.044). To better understand WBS application in practice, response surface methodology was developed to predict TCE adsorption capacity and emissions through WBS in different landfills in China. These results indicated that WBS had high adsorption capacity of TCE in LFG and temperature should be paid more attention to manipulate WBS to reduce TCE emissions from landfills.

  13. Hydrogeology and soil gas at J-Field, Aberdeen Proving Ground, Maryland

    USGS Publications Warehouse

    Hughes, W.B.

    1993-01-01

    Disposal of chemical warfare agents, munitions, and industrial chemicals in J-Field, Aberdeen Proving Ground, Maryland, has contaminated soil, groundwater and surface water. Seven exploratory borings and 38 observation wells were drilled to define the hydrogeologic framework at J-Field and to determine the type, extent, and movement of contaminants. The geologic units beneath J-Field consist of Coastal Plain sediments of the Cretaceous Patapsco Formation and Pleistocene Talbot Formation. The Patapsco Formation contains several laterally discontinuous aquifers and confining units. The Pleistocene deposits were divided into 3 hydrogeologic units--a surficial aquifer, a confining unit, and a confined aquifer. Water in the surficial aquifer flows laterally from topographically high areas to discharge areas in marshes and streams, and vertically to the underlying confined aquifer. In offshore areas, water flows from the deeper confined aquifers upward toward discharge areas in the Gunpowder River and Chesapeake Bay. Analyses of soil-gas samples showed high relative-flux values of chlorinated solvents, phthalates, and hydrocarbons at the toxic-materials disposal area, white-phosphorus disposal area, and riot-control-agent disposal area. The highest flux values were located downgradient of the toxic materials and white phosphorus disposal areas, indicating that groundwater contaminants are moving from source areas beneath the disposal pits toward discharge points in the marshes and estuaries. Elevated relative-flux values were measured upgradient and downgradient of the riot-control agent disposal area, and possibly result from soil and (or) groundwater contamination.

  14. VARIATIONS IN SOIL AGGREGATE STABILITY AND ENZYME ACTIVITIES IN A TEMPERATE AGROFORESTRY PRACTICE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agroforestry and grass buffers have been shown to improve soil properties and overall environmental quality. The objective of this study was to examine management and landscape effects on water stable soil aggregates (WSA), soil carbon, soil nitrogen, enzyme activity, and microbial community DNA co...

  15. Soil type is the primary determinant of the composition of the total and active bacterial communities in arable soils.

    PubMed

    Girvan, Martina S; Bullimore, Juliet; Pretty, Jules N; Osborn, A Mark; Ball, Andrew S

    2003-03-01

    Degradation of agricultural land and the resulting loss of soil biodiversity and productivity are of great concern. Land-use management practices can be used to ameliorate such degradation. The soil bacterial communities at three separate arable farms in eastern England, with different farm management practices, were investigated by using a polyphasic approach combining traditional soil analyses, physiological analysis, and nucleic acid profiling. Organic farming did not necessarily result in elevated organic matter levels; instead, a strong association with increased nitrate availability was apparent. Ordination of the physiological (BIOLOG) data separated the soil bacterial communities into two clusters, determined by soil type. Denaturing gradient gel electrophoresis and terminal restriction fragment length polymorphism analyses of 16S ribosomal DNA identified three bacterial communities largely on the basis of soil type but with discrimination for pea cropping. Five fields from geographically distinct soils, with different cropping regimens, produced highly similar profiles. The active communities (16S rRNA) were further discriminated by farm location and, to some degree, by land-use practices. The results of this investigation indicated that soil type was the key factor determining bacterial community composition in these arable soils. Leguminous crops on particular soil types had a positive effect upon organic matter levels and resulted in small changes in the active bacterial population. The active population was therefore more indicative of short-term management changes.

  16. Mass-dependent Corrections and Atmospheric Invasion: Working with the Radiocarbon Content of CO2 in the Soil Gas Environment

    NASA Astrophysics Data System (ADS)

    Egan, J. E.; Bowling, D. R.; Risk, D. A.

    2014-12-01

    Radiocarbon is becoming a more commonly utilized tool for C cycling studies, as it helps constrain biotic ecosystem processes such as C turnover times and sources of production. However, for studies that focus on CO2, the sampling methods for Δ14CO2 (surface chambers and subsurface gas wells) can be affected by abiotic processes, which may bias results as a function of gas transport regime (diffusion and advection). The radiocarbon community currently uses a δ13C correction to account for mass-dependent fractionation, but to date this correction has not been validated for the soil gas environment, where atmospheric invasion and gas transport are important. This study used an analytical soil gas transport model across a range of soil diffusivities and production rates, in which we could control Δ14CO2 and δ13CO2 signatures of production and atmosphere. This synthetic situation allowed us to assess the bias that results from using the conventional correction method for estimating Δ14CO2 of soil production. We found that the conventional correction is not strictly valid in this setting for interpreting the signature of production and does not account for diffusion and atmospheric invasion. The resultant Δ14CO2 bias scales with soil diffusivity and production rates. We propose a new two-step correction for Δ14CO2 work in the soil environment that accounts for atmospheric invasion and the δ13CO2 correction, and is able to reproduce a true value of Δ14CO2 of production. This work not only assists in data interpretation, but also helps clarify a methodological window of opportunity for accurately measuring the Δ14CO2 of soil production using subsurface sampling.

  17. Modelling Trace Gas Gluxes From Soils Along Slope Transects in Eastern Canadian Forest Ecosystems

    NASA Astrophysics Data System (ADS)

    Peng, C.; Chen, X.; Ullah, S.; Moore, T.; Li, C.

    2009-05-01

    Trace gases exchange between forest soils and atmosphere is important for Green House Gases (GHG) budget at both national and global scales. However, this part has not been included in the Canadian national GHG inventory yet. Although several sites have flux measurements, accurate larger scale fluxes are difficult to estimate due to the nature of spatial and temporal variability for gas generation and consumption processes. This study aims to simulate trace gas fluxes (mainly CH4 and N2O) at different landscape scales, using the process-based Forest-DNDC model. As the first part of the work, model has been parameterized and validated against flux measurements along slope transects at two deciduous forest stands at Mt. St. Hilaire (MSH) and Morgan Arboretum (MA), near Montreal, Quebec. The preliminary results suggest that both N2O and CH4 fluxes have two peaks during a year corresponding to snow melting and summer rain, respectively. The upland, riparian zone and wetland area at the two sites are sources of N gases dominated by N2O and N2. Both upland area and riparian zone act as a CH4 sink, while wetland a net source of CH4. Forest successional stage, tree species composition and the decomposition status of forest floor are possible controls on N gaseous flux at site level. The validation results proved that Forest-DNDC is able to capture trace gas exchange in different forest soils. The modeled patterns and magnitudes of fluxes were basically in agreement with observations for all studied plots. Further works for parameter optimization with inversion techniques are expected to improve the model performance before extrapolating the model to larger scale.

  18. Oxidation and cyclization of organics in Mars-like soils during evolved gas analysis

    NASA Astrophysics Data System (ADS)

    Navarro-Gonzalez, Rafael; Iñiguez, Enrique; de La Rosa, Jose; McKay, Chris

    , doi:10.1029/2009GL040454. Navarro-González, R., Navarro, K.F., de la Rosa, J., Molina, P., Iñiguez, E., Miranda, L.D., a n Morales, P., Cienfuegos, E., Coll, P., Raulin, F., Amils, R. and McKay, C.P.: 2006. The limitations on organic detection in Mars-like soils by thermal volatilization-gas chromatography-MS and their implications for the Viking results. Proc Natl Acad Sci USA 103, 16089-16094. Navarro-González, R., Iñiguez, E., de la Rosa, J. and McKay, C.P.: 2009, Characterization of a n organics, microorganisms, desert soils and Mars-like soils by thermal volatilization coupled to mass spectrometry and their implications for the search of organics on Mars by Phoenix and future space missions. Astrobiology 9, 703-715, doi: 10.1089/ast.2008.0284.

  19. The level and distribution of ²²⁰Rn concentration in soil-gas in Guangdong Province, China.

    PubMed

    Wang, N; Peng, A; Xiao, L; Chu, X; Yin, Y; Qin, C; Zheng, L

    2012-11-01

    In order to understand the level and distribution of (220)Rn concentrations in soil-gas in the high-radiation-background area, an (220)Rn survey was carried out for the first time using a RAD7 portable radon monitor at 67 locations covering a total area of 1800 km(2) in the South of China. (220)Rn concentrations were significantly different from that in the surface areas covered by the weathered granite of Yanshan Period or Quaternary sediments. The (220)Rn concentrations varied between 6.65 and 461 kBq m(-3) and the averages were 294.42 ± 81.36 and 23.30 ± 25.84 kBq m(-3) for weathered granite products and sediments, respectively. A high positive correlation between (220)Rn concentrations and (232)Th activity concentrations was found. (220)Rn concentrations had no statistically significant variations from depths of 20-140 cm with an interval of 20 cm. It is worth paying attention to the problem of such a high soil (220)Rn concentration in Zhuhai City and Zhongshan City.

  20. Mineral exploration and soil analysis using in situ neutron activation

    USGS Publications Warehouse

    Senftle, F.E.; Hoyte, A.F.

    1966-01-01

    A feasibility study has been made to operate by remote control an unshielded portable positive-ion accelerator type neutron source to induce activities in the ground or rock by "in situ" neutron irradiation. Selective activation techniques make it possible to detect some thirty or more elements by irradiating the ground for periods of a few minutes with either 3-MeV or 14-MeV neutrons. The depth of penetration of neutrons, the effect of water content of the soil on neutron moderation, gamma ray attenuation in the soil and other problems are considered. The analysis shows that, when exploring for most elements of economic interest, the reaction 2H(d,n)3He yielding ??? 3-MeV neutrons is most practical to produce a relatively uniform flux of neutrons of less than 1 keV to a depth of 19???-20???. Irradiation with high energy neutrons (??? 14 MeV) can also be used and may be better suited for certain problems. However, due to higher background and lower sensitivity for the heavy minerals, it is not a recommended neutron source for general exploration use. Preliminary experiments have been made which indicate that neutron activation in situ is feasible for a mineral exploration or qualititative soil analysis. ?? 1976.

  1. The NASA Soil Moisture Active Passive (SMAP) Mission Formulation

    NASA Technical Reports Server (NTRS)

    Entekhabi, Dara; Njoku, Eni; ONeill, Peggy; Kellogg, Kent; Entin, Jared

    2011-01-01

    The Soil Moisture Active Passive (SMAP) mission is one of the first-tier projects recommended by the U.S. National Research Council Committee on Earth Science and Applications from Space. The SMAP mission is in formulation phase and it is scheduled for launch in 2014. The SMAP mission is designed to produce high-resolution and accurate global mapping of soil moisture and its freeze/thaw state using an instrument architecture that incorporates an L-band (1.26 GHz) radar and an L-band (1.41 GHz) radiometer. The simultaneous radar and radiometer measurements will be combined to derive global soil moisture mapping at 9 [km] resolution with a 2 to 3 days revisit and 0.04 [cm3 cm-3] (1 sigma) soil water content accuracy. The radar measurements also allow the binary detection of surface freeze/thaw state. The project science goals address in water, energy and carbon cycle science as well as provide improved capabilities in natural hazards applications.

  2. Greenhouse gas budgets for grasslands on peatlands and other organic soils

    NASA Astrophysics Data System (ADS)

    Tiemeyer, Bärbel; Albiac Borraz, Elisa; Augustin, Jürgen; Bechtold, Michel; Beetz, Sascha; Beyer, Colja; Eickenscheidt, Tim; Drösler, Matthias; Förster, Christoph; Freibauer, Annette; Giebels, Michael; Glatzel, Stephan; Heinichen, Jan; Hoffmann, Mathias; Höper, Heinrich; Leiber-Sauheitl, Katharina; Rosskopf, Niko; Zeitz, Jutta

    2014-05-01

    Drained peatlands are hotspots of greenhouse gas (GHG) emissions. Grassland is the major land use type for peatlands in Germany and other European countries, but strongly varies in its intensity regarding the groundwater level and the agricultural management. These parameters are known to influence the GHG emissions. Furthermore, little is known about the emissions from grasslands on soils which are rich in organic matter, but cannot be classified as peatlands (e.g. Histic Gleysols). We synthesized 116 annual GHG budgets for 46 different sites in 11 German peatlands. Carbon dioxide (net ecosystem exchange and ecosystem respiration), nitrous oxide and methane fluxes were measured with transparent and opaque manual chambers. Land management ranged from very intensive use with up to five cuts per year to re-wetted grasslands with only one cut late in the year. Besides the GHG fluxes, biomass yield, fertilisation, groundwater level, climatic data, vegetation composition and soil properties were measured. Overall, we found a large variability of the total GHG budget ranging from small uptakes (- 6 t CO2- equivalents/(ha yr)) to very high losses (74 t CO2-equivalents/(ha yr)). At all sites, the GHG budget was dominated by carbon dioxide, generally followed by biomass export. Surprisingly, there was no difference between the average GHG budget of the peatlands and of the other organic soils. Thus, the GHG budget did not depend on soil organic carbon concentration or stock. Generally, the groundwater table depth was the best predictor for GHG emissions at each individual peatland, but a poor overall predictor. For all sites, the GHG budget was explained best by the average nitrogen stock above the mean groundwater level.

  3. 40 CFR Table Hh-3 to Subpart Hh of... - Landfill Gas Collection Efficiencies

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...: Area with daily soil cover and active gas collection CE3: 60%. A4: Area with an intermediate soil cover, or a final soil cover not meeting the criteria for A5 below, and active gas collection CE4: 75%. A5: Area with a final soil cover of 3 feet or thicker of clay and/or geomembrane cover system and...

  4. 40 CFR Table Hh-3 to Subpart Hh of... - Landfill Gas Collection Efficiencies

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...: Area with daily soil cover and active gas collection CE3: 60%. A4: Area with an intermediate soil cover, or a final soil cover not meeting the criteria for A5 below, and active gas collection CE4: 75%. A5: Area with a final soil cover of 3 feet or thicker of clay and/or geomembrane cover system and...

  5. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence.

    PubMed

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-10-27

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist.

  6. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence

    PubMed Central

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-01-01

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist. PMID:26503629

  7. Identification of Alternative Vapor Intrusion Pathways Using Controlled Pressure Testing, Soil Gas Monitoring, and Screening Model Calculations.

    PubMed

    Guo, Yuanming; Holton, Chase; Luo, Hong; Dahlen, Paul; Gorder, Kyle; Dettenmaier, Erik; Johnson, Paul C

    2015-11-17

    Vapor intrusion (VI) pathway assessment and data interpretation have been guided by an historical conceptual model in which vapors originating from contaminated soil or groundwater diffuse upward through soil and are swept into a building by soil gas flow induced by building underpressurization. Recent studies reveal that alternative VI pathways involving neighborhood sewers, land drains, and other major underground piping can also be significant VI contributors, even to buildings beyond the delineated footprint of soil and groundwater contamination. This work illustrates how controlled-pressure-method testing (CPM), soil gas sampling, and screening-level emissions calculations can be used to identify significant alternative VI pathways that might go undetected by conventional sampling under natural conditions at some sites. The combined utility of these tools is shown through data collected at a long-term study house, where a significant alternative VI pathway was discovered and altered so that it could be manipulated to be on or off. Data collected during periods of natural and CPM conditions show that the alternative pathway was significant, but its presence was not identifiable under natural conditions; it was identified under CPM conditions when measured emission rates were 2 orders of magnitude greater than screening-model estimates and subfoundation vertical soil gas profiles changed and were no longer consistent with the conventional VI conceptual model.

  8. Comparative resistance and resilience of soil microbial communities and enzyme activities in adjacent native forest and agricultural soils.

    PubMed

    Chaer, Guilherme; Fernandes, Marcelo; Myrold, David; Bottomley, Peter

    2009-08-01

    Degradation of soil properties following deforestation and long-term soil cultivation may lead to decreases in soil microbial diversity and functional stability. In this study, we investigated the differences in the stability (resistance and resilience) of microbial community composition and enzyme activities in adjacent soils under either native tropical forest (FST) or in agricultural cropping use for 14 years (AGR). Mineral soil samples (0 to 5 cm) from both areas were incubated at 40 degrees C, 50 degrees C, 60 degrees C, or 70 degrees C for 15 min in order to successively reduce the microbial biomass. Three and 30 days after the heat shocks, fluorescein diacetate (FDA) hydrolysis, cellulase and laccase activities, and phospholipid-derived fatty acids-based microbial community composition were measured. Microbial biomass was reduced up to 25% in both soils 3 days after the heat shocks. The higher initial values of microbial biomass, enzyme activity, total and particulate soil organic carbon, and aggregate stability in the FST soil coincided with higher enzymatic stability after heat shocks. FDA hydrolysis activity was less affected (more resistance) and cellulase and laccase activities recovered more rapidly (more resilience) in the FST soil relative to the AGR counterpart. In the AGR soil, laccase activity did not show resilience to any heat shock level up to 30 days after the disturbance. Within each soil type, the microbial community composition did not differ between heat shock and control samples at day 3. However, at day 30, FST soil samples treated at 60 degrees C and 70 degrees C contained a microbial community significantly different from the control and with lower biomass regardless of high enzyme resilience. Results of this study show that deforestation followed by long-term cultivation changed microbial community composition and had differential effects on microbial functional stability. Both soils displayed similar resilience to FDA hydrolysis, a

  9. Physiologically available cyanide (PAC) in manufactured gas plant waste and soil samples

    SciTech Connect

    Magee, B.; Taft, A.; Ratliff, W.; Kelley, J.; Sullivan, J.; Pancorbo, O.

    1995-12-31

    Iron-complexed cyanide compounds, such as ferri-ferrocyanide (Prussian Blue), are wastes associated with former manufactured gas plant (MGP) facilities. When tested for total cyanide, these wastes often show a high total cyanide content. Because simple cyanide salts are acutely toxic, cyanide compounds can be the subject of concern. However, Prussian Blue and related species are known to have a low order of human and animal toxicity. Toxicology data on complexed cyanides will be presented. Another issue regarding Prussian Blue and related species is that the total cyanide method does not accurately represent the amount of free cyanide released from these cyanide species. The method involves boiling the sample in an acidic solution under vacuum to force the formation of HCN gas. Thus, Prussian Blue, which is known to be low in toxicity, cannot be properly evaluated with current methods. The Massachusetts Natural Gas Council initiated a program with the Massachusetts Department of Environmental Protection to develop a method that would define the amount of cyanide that is able to be converted into hydrogen cyanide under the pH conditions of the stomach. It is demonstrated that less than 1% of the cyanide present in Prussian Blue samples and soils from MGP sites can be converted to HCN under the conditions of the human stomach. The physiologically available cyanide method has been designed to be executed at a higher temperature for one hour. It is shown that physiologically available cyanide in MGP samples is < 5--15% of total cyanide.

  10. [Effects of earthworm inoculation and straw amendment on soil microflora and microbial activity in Cu contaminated soil].

    PubMed

    Wang, Dan-dan; Li, Hui-xin; Wei, Zheng-gui; Liu, Man-qiang; Wang, Xia; Hu, Feng

    2007-05-01

    In this paper, the dynamics of microflora and microbial activity in soil added with 0, 100, 200 and 400 mg x kg(-1) of Cu2+ were studied under effects of inoculating earthworm and applying straw. Four treatments were installed, i.e., CK, surface application of straw (M), inoculation of earthworm (E), and M plus E (ME). The results showed that Cu contamination had inhibitory effect on soil bacteria and actinomycetes, but no effect on soil fungi. Straw amendment increased soil fungi significantly, while earthworm inoculation could increase the numbers of soil bacteria and actinomycetes significantly but had little effect on soil fungi. When the Cu concentration was higher than 200 mg x kg(-1, soil microbial biomass carbon was depressed, but earthworm inoculation and straw amendment could enhance it, with most significant effect under the combination of these two treatments. Earthworm inoculation and straw amendment could enhance soil basal respiration markedly. When the Cu concentration was lower than 200 mg x kg(-1), treatment M had the highest soil basal respiration, being about 3.06-5.58 times higher than that of CK, while at Cu > or =200 mg x kg(-1), soil qCO2 followed the sequence of ME > E > M > CK. Treatments M and E had no effects on soil NH4+ -N. As for soil NO3- -N, treatment E could increase it significantly, but treatment M was in adverse. Treatment ME induced the lowest soil NO3- -N. In a definite degree, earthworm inoculation and straw amendment could mitigate the negative impact of Cu contamination on soil microflora and microbial activity.

  11. Assessment of hyporheic zone, flood-plain, soil-gas, soil, and surface-water contamination at the Old Incinerator Area, Fort Gordon, Georgia, 2009-2010

    USGS Publications Warehouse

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

    2011-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of the Army Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon, Georgia, assessed the hyporheic zone, flood plain, soil gas, soil, and surface-water for contaminants at the Old Incinerator Area at Fort Gordon, from October 2009 to September 2010. The assessment included the detection of organic contaminants in the hyporheic zone, flood plain, soil gas, and surface water. In addition, the organic contaminant assessment included the analysis of explosives and chemical agents in selected areas. Inorganic contaminants were assessed in soil and surface-water samples. The assessment was conducted to provide environmental contamination data to the U.S. Army at Fort Gordon pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Total petroleum hydrocarbons were detected above the method detection level in all 13 samplers deployed in the hyporheic zone and flood plain of an unnamed tributary to Spirit Creek. The combined concentrations of benzene, toluene, ethylbenzene, and total xylene were detected at 3 of the 13 samplers. Other organic compounds detected in one sampler included octane and trichloroethylene. In the passive soil-gas survey, 28 of the 60 samplers detected total petroleum hydrocarbons above the method detection level. Additionally, 11 of the 60 samplers detected the combined masses of benzene, toluene, ethylbenzene, and total xylene above the method detection level. Other compounds detected above the method detection level in the passive soil-gas survey included octane, trimethylbenzene, perchlorethylene, and chloroform. Subsequent to the passive soil-gas survey, six areas determined to have relatively high contaminant mass were selected, and soil-gas samplers were deployed, collected, and analyzed for explosives and chemical agents. No explosives or chemical agents were detected above

  12. Soil extracellular enzyme activities, soil carbon and nitrogen storage under nitrogen fertilization: A meta-analysis

    DOE PAGES

    Jian, Siyang; Li, Jianwei; Chen, Ji; ...

    2016-07-08

    Nitrogen (N) fertilization affects the rate of soil organic carbon (SOC) decomposition by regulating extracellular enzyme activities (EEA). Extracellular enzymes have not been represented in global biogeochemical models. Understanding the relationships among EEA and SOC, soil N (TN), and soil microbial biomass carbon (MBC) under N fertilization would enable modeling of the influence of EEA on SOC decomposition. Based on 65 published studies, we synthesized the activities of α-1,4-glucosidase (AG), β-1,4-glucosidase (BG), β-d-cellobiosidase (CBH), β-1,4-xylosidase (BX), β-1,4-N-acetyl-glucosaminidase (NAG), leucine amino peptidase (LAP), urease (UREA), acid phosphatase (AP), phenol oxidase (PHO), and peroxidase (PEO) in response to N fertilization. Here, themore » proxy variables for hydrolytic C acquisition enzymes (C-acq), N acquisition (N-acq), and oxidative decomposition (OX) were calculated as the sum of AG, BG, CBH and BX; AG and LAP; PHO and PEO, respectively.« less

  13. Measurement of N2, N2O, NO, and CO2 emissions from soil with the gas-flow-soil-core technique.

    PubMed

    Wang, Rui; Willibald, Georg; Feng, Qi; Zheng, Xunhua; Liao, Tingting; Brüggemann, Nicolas; Butterbach-Bahl, Klaus

    2011-07-15

    Here we describe a newly designed system with three stand-alone working incubation vessels for simultaneous measurements of N(2), N(2)O, NO, and CO(2) emissions from soil. Due to the use of a new micro thermal conductivity detector and the redesign of vessels and gas sampling a so-far unmatched sensitivity (0.23 μg N(2)-N h(-1) kg(-1) ds or 8.1 μg N(2)-N m(-2) h(-1)) for detecting N(2) gas emissions and repeatability of experiments could be achieved. We further tested different incubation methods to improve the quantification of N(2) emission via denitrification following the initialization of soil anaerobiosis. The best results with regard to the establishment of a full N balance (i.e., the changes in mineral N content being offset by simultaneous emission of N gases) were obtained when the anaerobic soil incubation at 25 °C was preceded by soil gas exchange under aerobic conditions at a lower incubation temperature. The ratios of N and C gas emission changed very dynamically following the initialization of anaerobiosis. For soil NO(3)(-) contents of 50 mg N kg(-1) dry soil (ds) and dissolved organic carbon (DOC) concentrations of approximately 300 mg C kg(-1) ds, the cumulative emissions of N(2), N(2)O, and NO were 24.3 ± 0.1, 12.6 ± 0.4, and 10.1 ± 0.3 mg N kg(-1) ds, respectively. Thus, N gas emissions accounted (on average) for 46.2% (N(2)), 24.0% (N(2)O), and 19.2% (NO) of the observed changes in soil NO(3)(-). The maximum N(2) emission reached 1200 μg N h(-1) kg(-1) ds, whereas the peak emissions of N(2)O and NO were lower by a factor of 2-3. The overall N(2):N(2)O and NO:N(2)O molar ratios were 1.6-10.0 and 1.6-2.3, respectively. The measurement system provides a reliable tool for studying denitrification in soil because it offers insights into the dynamics and magnitude of gaseous N emissions due to denitrification under various incubation conditions.

  14. Modification of the activity of some C cycle hydrolases in soils afforested with Populus alba L. Preliminary results

    NASA Astrophysics Data System (ADS)

    Zorita, Félix; García-Campos, Elena; Gil-Sotres, Fernando; Leirós, Mā Carmen; Trasar-Cepeda, Carmen

    2010-05-01

    Since 1992 a large part of the agricultural land in Galicia (NW Spain) has disappeared as a result of the EU policy of providing grants and aid for transforming marginal land into forest terrain. In Galicia, this policy (EU Regulation 2080/1992) has mainly been applied to good quality agricultural land rather than to marginal land. As a result, the land has undergone a change in use, so that previously good quality agricultural land is now planted with various species of trees, usually of young age. Despite the large area of land transformed, until now the environmental cost of such changes has not been evaluated. Taking into account that one of the possible environmental effects derived from land transformation is changes in emissions of CO2 (a major greenhouse gas), it is therefore essential to evaluate any possible modifications undergone in such soils, with special attention given to biochemical properties, i.e. the properties that determine edaphic metabolism. With this aim, we are currently investigating the effect of afforestation on diverse biochemical properties, including the activity of hydrolytic enzymes involved in the C, N, P and S cycles, in a large number of afforested soils, planted with different trees and located in different areas throughout Galicia. In each case, an agricultural soil located close to the afforested soil, but under the original land use (usually maize cropped soils or pasture soils), is also collected and analysed, and the results obtained for afforested soils compared with those for the corresponding agricultural soils. Here we report some preliminary results on modifications in the activities of some C cycle hydrolases in six soils now planted with poplars, Populus alba L, but originally cropped with maize. Samples of all soils were collected in autumn, after harvesting and before any other agricultural activities were carried out. In all cases, the upper 10 cm of the soils were collected. The soils were sieved (4 mm) prior to

  15. Tracer test for the measurement of gas diffusion and non-aqueous phase liquid (NAPL) saturation in soil.

    PubMed

    Van De Steene, Joke; Höhener, Patrick

    2009-01-01

    During soil bioremediation, the diffusion of oxygen into the soil is an important prerequisite for aerobic biodegradation, and the decrease of petroleum products is the ultimate goal. Both processes need to be monitored. The aim of this work was to develop a gas tracer test that yields information on both, gas diffusion and residual saturation with non-aqueous phase liquids (NAPLs) in unsaturated soil heaps. One conservative tracer (methane) and 4 partitioning gas tracers (diethylether, methyl tert-butyl ether, chloroform and n-heptane) were injected as vapors into laboratory columns filled with unsaturated sand with increasing NAPL saturation. Breakthrough curves of gaseous compounds were measured at two points and compared to analytical solutions of an analytical diffusive-reactive transport equation. By fitting of methane data, robust results for effective diffusivity (tortuosity) were obtained. NAPL saturation was most accurately measured by the moderately water soluble tracers (ethers and chloroform). The hydrophobic tracer n-heptane did not partition into water-immersed NAPL. An easy and accurate way to assess air-NAPL partitioning constants from gas chromatography retention times is furthermore reported. It is concluded that gas tracer tests have the potential for measuring two important properties in soil bioremediation systems easily and quickly.

  16. [Effects of growing time on Panax ginseng rhizosphere soil microbial activity and biomass].

    PubMed

    Xiao, Chun-ping; Yang, Li-min; Ma, Feng-min

    2014-12-01

    Using the field sampling and indoor soil cultivation methods, the dynamic of ginseng rhizosphere soil microbial activity and biomass with three cultivated ages was studied to provide a theory basis for illustrating mechanism of continuous cropping obstacles of ginseng. The results showed that ginseng rhizosphere soil microbial activity and biomass accumulation were inhibited observably by growing time. The soil respiration, soil cellulose decomposition and soil nitrification of ginseng rhizosphere soil microorganism were inhibited significantly (P <0.05), in contrast to the control soil uncultivated ginseng (R0). And the inhibition was gradual augmentation with the number of growing years. The soil microbial activity of 3a ginseng soil (R3) was the lowest, and its activity of soil respiration, soil cellulose decomposition, soil ammonification and soil nitrification was lower than that in R0 with 56.31%, 86.71% and 90. 53% , respectively. The soil ammonification of ginseng rhizosphere soil microbial was significantly promoted compared with R0. The promotion was improved during the early growing time, while the promotion was decreased with the number of growing years. The soil ammonification of R1, R2 and R3 were lower than that in R0 with 32.43%, 80.54% and 66.64% separately. The SMB-C and SMB-N in ginseng rhizosphere soil had a decreased tendency with the number of growing years. The SMB-C difference among 3 cultivated ages was significant, while the SMB-N was not. The SMB of R3 was the lowest. Compared with R0, the SMB-C and the SMB-N were significantly reduced 77.30% and 69.36%. It was considered by integrated analysis that the leading factor of continuous cropping obstacle in ginseng was the changes of the rhizosphere soil microbial species, number and activity as well as the micro-ecological imbalance of rhizosphere soil caused by the accumulation of ginseng rhizosphere secretions.

  17. Influence of Anthropogenic Nutrient Additions on Greenhouse Gas Production Rates at Water-soil Interfaces in an Urban Dominated Estuary

    NASA Astrophysics Data System (ADS)

    Brigham, B. A.; O'Mullan, G. D.; Bird, J. A.

    2014-12-01

    The tidal Hudson River Estuary (HRE) receives significant inputs of readily dissolvable carbon (C) and nitrogen (N) from incomplete wastewater treatment and sewer overflow during storm events associated with NYC and other urban centers. Nutrient deposition may alter C utilization in the estuarine water column, associated sediments and surrounding wetlands. In these anaerobic systems, we hypothesize that microbial activity is limited by the availability of easily-degradable C (not electron acceptors), which acts as a co-metabolite and provides energy for organic matter decomposition. Sporadic transport of highly C enriched storm derived runoff may substantially enhance greenhouse gas (GHG) production rates through the utilization of stored C pools. To test our hypothesis carbon dioxide (CO2) and methane (CH4) process rates (1) were evaluated from soil cores removed from three distinct HRE wetland sites (Saw Mill Creek, Piermont, and Iona Island Marsh(s)) across a salinity gradient and incubated under varying nutrient treatments. Further, CO2 and CH4 surface water effluxes (2) were quantified from multiple river cruises spanning two years at varying distance from nutrient sources associated with NYC. Incubation experiments from wetland