Topic
Soil gas
About: Soil gas is a research topic. Over the lifetime, 1889 publications have been published within this topic receiving 36003 citations.
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Papers
TL;DR: In this paper, the authors developed a below-ground carbon budget for well-drained soils in Harvard Forest Massachusetts, an ecosystem that is storing C. Measurements of carbon and radiocarbon inventory were used to determine the turnover time and maximum rate of CO2 production from heterotrophic respiration of three fractions of soil organic matter (SOM): recognizable litter fragments (L), humified low density material (H), and high density or mineral-associated organic matter(M).
Abstract: Temperate forests of North America are thought to be significant sinks of atmospheric CO2. We developed a below-ground carbon (C) budget for well-drained soils in Harvard Forest Massachusetts, an ecosystem that is storing C. Measurements of carbon and radiocarbon ( 14 C) inventory were used to determine the turnover time and maximum rate of CO2 production from heterotrophic respiration of three fractions of soil organic matter (SOM): recognizable litter fragments (L), humified low density material (H), and high density or mineral-associated organic matter (M). Turnover times in all fractions increased with soil depth and were 2-5 years for recognizable leaf litter, 5-10 years for root litter, 40-100+ years for low density humified material and >100 years for carbon associated with minerals. These turnover times represent the time carbon resides in the plant + soil system, and may underestimate actual decomposition rates if carbon resides for several years in living root, plant or woody material. Soil respiration was partitioned into two components using 14 C: recent photosynthate which is metabolized by roots and microorganisms within a year of initial fixation (Recent- C), and C that is respired during microbial decomposition of SOM that resides in the soil for several years or longer (Reservoir-C). For the whole soil, we calculate that decomposition of Reservoir-C contributes approximately 41% of the total annual soil respiration. Of this 41%, recognizable leaf or root detritus accounts for 80% of the flux, and 20% is from the more humified fractions that dominate the soil carbon stocks. Measurements of CO 2 and 14 CO2 in the soil atmosphere and in total soil respiration were combined with surface CO2 fluxes and a soil gas diffusion model to determine the flux and isotopic signature of C produced as a function of soil depth. 63% of soil respiration takes place in the top 15 cm of the soil (O + A + Ap horizons). The average residence time of Reservoir-C in the plant + soil system is 81 years and the average age of carbon in total soil respiration (Recent-C + Reservoir-C) is 41 years. The O and A horizons have accumulated 4.4 kgC m -- 2 above the plow layer since abandon- ment by settlers in the late-1800's. C pools contributing the most to soil respiration have short enough turnover times that they are likely in steady state. However, most C is stored as humified organic matter within both the O and A horizons and has turnover times from 40 to
674 citations
TL;DR: In this article, the authors reviewed the factors that control the rate at which two radon isotopes, 222Rn and 220Rn, enter outdoor and indoor air from soil.
Abstract: Radon generated within the upper few meters of the Earth's crust by the radioactive decay of radium can migrate during its brief lifetime from soil into the atmosphere. This phenomenon leads to a human health concern as inhalation of the short-lived decay products of radon causes irradiation of cells lining the respiratory tract. This paper reviews the factors that control the rate at which two radon isotopes, 222Rn and 220Rn, enter outdoor and indoor air from soil. The radium content of surface soils in the United States is usually in the range 10–100 Bq kg−1. The emanation coefficient, which refers to the fraction of radon generated in a material that enters the pore fluids, varies over a wide range with a typical value being 0.2. Radon in soil pores may be partitioned among three states: in the pore air, dissolved in the pore water, and sorbed to the soil grains. Except in the immediate vicinity of buildings, radon migrates through soil pores principally by molecular diffusion. Average reported flux densities from undisturbed soil into the atmosphere are 0.015–0.048 Bq m−2 s−1 for 222Rn and 1.6–1.7 Bq m−2 s−1 for 220Rn. Soil is the dominant source of radon in most buildings. Advective flow of soil gas across substructure penetrations is a key element in the transport process. The advective flow is driven by the weather (wind and indoor-outdoor temperature differences) and by the operation of building systems, such as heating and air conditioning equipment. A typical radon entry rate into a single-family dwelling of 10–15 kBq h−1 can be accounted for by weather-induced pressure-driven flow through moderately to highly permeable soils. The extent to which diffusion through soil pores contributes to radon entry into buildings is not known, but in buildings with elevated concentrations, diffusion is believed to be less important than advection.
654 citations
TL;DR: In this article, the impact of drying-rewetting events and thawing of frozen soils on larger scale ecosystem fluxes is increasingly recognized, and a growing number of studies show that these events affect fluxes of soil gases such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ammonia (NH3) and nitric oxide (NO).
Abstract: . The rewetting of dry soils and the thawing of frozen soils are short-term, transitional phenomena in terms of hydrology and the thermodynamics of soil systems. The impact of these short-term phenomena on larger scale ecosystem fluxes is increasingly recognized, and a growing number of studies show that these events affect fluxes of soil gases such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ammonia (NH3) 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. These future scenarios highlight the importance of understanding how rewetting and thawing will influence dynamics of these soil gases. This study summarizes findings using a new database containing 338 studies conducted from 1956 to 2011, and highlights open research questions. The database revealed conflicting results following rewetting and thawing in various terrestrial ecosystems and among soil gases, ranging from large increases in fluxes to non-significant changes. Studies reporting lower gas fluxes before rewetting tended to find higher post-rewetting fluxes for CO2, N2O and NO; in addition, increases in N2O flux following thawing were greater in warmer climate regions. We discuss possible mechanisms and controls that regulate flux responses, and recommend that a high temporal resolution of flux measurements is critical to capture rapid changes in gas fluxes after these soil perturbations. Finally, we propose that future studies should investigate the interactions between biological (i.e., microbial community and gas production) and physical (i.e., porosity, diffusivity, dissolution) changes in soil gas fluxes, apply techniques to capture rapid changes (i.e., automated measurements), and explore synergistic experimental and modelling approaches.
488 citations
TL;DR: In this paper, the authors used observations of N gas loss from incubations of intact and disturbed soil cores to model N2O and N2 emissions from soil as a result of denitrification.
Abstract: Observations of N gas loss from incubations of intact and disturbed soil cores were used to model N2O and N2 emissions from soil as a result of denitrification. The model assumes that denitrification rates are controlled by the availability in soil of NO3 (e− acceptor), labile C compounds (e− donor), and O2 (competing e− acceptor). Heterotrophic soil respiration is used as a proxy for labile C availability while O2 availability is a function of soil physical properties that influence gas diffusivity, soil WFPS, and O2 demand. The potential for O2 demand, as indicated by respiration rates, to contribute to soil anoxia varies inversely with a soil gas diffusivity coefficient which is regulated by soil porosity and pore size distribution. Model inputs include soil heterotrophic respiration rate, texture, NO3 concentration, and WFPS. The model selects the minimum of the NO3 and CO2 functions to establish a maximum potential denitrification rate for particular levels of e− acceptor and C substrate and accounts for limitation of O2 availability to estimate daily N2+N2O flux rates. The ratio of soil NO3 concentration to CO2 emission was found to reliably (r2=0.5) model the ratio of N2 to N2O gases emitted from the intact cores after accounting for differences in gas diffusivity among the soils. The output of the ratio function is combined with the estimate of total N gas flux rate to infer N2O emission. The model performed well when comparing observed and simulated values of N2O flux rates with the data used for model building (r2=0.50) and when comparing observed and simulated N2O+N2 gas emission rates from irrigated field soils used for model testing (r2=0.47).
439 citations
28 Dec 2001
TL;DR: In this article, the authors present an analytical model of the Advection-Dispersion Equation (ADE) for water flow in saturated and unsaturated soil.
Abstract: Introduction, A.W. Warrick Physical Properties of Primary Particles, J.M. Skopp Particle Density Particle Shape Particle Size Distribution Specific Surface Area Bulk Density and Porosity References Dynamic Properties of Soil, R. Horn and T. Baumgartl Introduction Processes in Aggregate Formation Determination of Mechanical Parameters Effect of Soil Structure and Dynamics on Strength and Stress/Strain Processes Further Dynamic Aspects in Soils Modeling Dynamic Coupled Processes Conclusions References Soil Water Content and Water Potential Relationships, D. Or and J.M. Wraith Introduction Soil Water Content Soil Water Energy Soil Water Content-Energy Relationships Resources References Soil Water Movement, D.E. Radcliffe and T.C. Rasmussen Introduction Flow in Saturated Soil Flow in Unsaturated Soil Measurement of Hydraulic Parameters Numerical Models of Water Flow Concluding Remarks References Water and Energy Balances at Soil-Plant-Atmosphere Interfaces, S.R. Evett Introduction Energy Balance Equation Water Balance Equation References Solute Transport, F.J. Leij and M.Th. van Genuchten Introduction The Advection-Dispersion Equation Solutions of the Advection-Dispersion Equation Stream Tube Models References Soil Structure, B.D. Kay and D.A. Angers Characteristics, Significance, and Measurement of Soil Structure Soil Factors Influencing Structure Other Factors Influencing Soil Structure Interpreting Data on Soil Structure References Soil Gas Movement in Unsaturated Systems, B.R. Scanlon, J.P. Nicot, and J.M. Massmann General Concepts Related to Gas Movement Transport of a Homogeneous Gas Multicomponent Gas Transport Methods Applied Numerical Modeling Applications of Gas Transport Theory Derivation of Equations References Soil Spatial Variability, D.J. Mulla and A.B. McBratney Variability in Soil Properties from Soil Classification Classical Measures of Variability Geostatistics Sampling Design References
331 citations
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Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 10 |
| 2024 | 22 |
| 2023 | 42 |
| 2022 | 71 |
| 2021 | 52 |
| 2020 | 53 |