Soil Air Concentrations Research Articles

Land-use effects on soil methane and carbon dioxide fluxes in forests near Ithaca, New York

:Consumption of atmospheric methane (CH4) and fluxes of carbon dioxide (CO2) were higher for soil in (i) mixed hardwood forest on historically unplowed land than in (ii) 80-year-old mixed hardwood forest and (iii) 80-year-old conifer plantations both established on post-agricultural land, whereas flux rates were lowest in (iv) adjoining agriculture sites, showing that past and present land-use in forest ecosystems affects fluxes of atmospheric CH4 and CO2. Site differences in CH4 fluxes were more pronounced in drier 1993 and 1995 than in wetter 1994, whereas site differences in CO2 fluxes disappeared during winter and during pronounced drought in summer 1995. Seasonal variation in CH4 fluxes in forest sites were related to soil moisture but not CH4 concentrations in soil air. Notably, all four sites occasionally exhibited CH4 efflux to the atmosphere, and studies confirmed the presence of anaerobic CH4-producing microorganisms (methanogens) in the soil, despite well-drained conditions. Seasonal variation in CO2 fluxes in forest sites were related to soil temperature and CO2 concentrations in soil air, but not in the agricultural site that maintained somewhat higher soil CO2 levels. Future studies of soil CH4 and CO2 dynamics should recognize the persistent effects of historical (and recent) changes in land use.

Evidence for effects of CO2 on soil solution chemistry in spodosols by a simple in‐field extractor

AbstractDegassing of CO2 during collection of soil solution may alter the chemical composition of the solution, especially in well‐buffered soils. We used a simple syringe extractor for field sampling of soil solution along with ambient soil air in order to test the influence of degassing of CO2 on solution pH in acid soils (Spodosol B and C horizons collected in Central Maine, USA). Soil air concentrations of CO2 varied from 0.36 to 1.35 ml l‐1 during sampling immediately after snow melt. Degassing increased solution pH by 0.3 to 0.5 pH units. Both in‐situ and degassed pH were predicted by the Reuss and Johnson soil chemical equilibrium model. The results suggest, (i) that the simple method is useful for determination of solution from wet soil under ambient soil air conditions and (ii) that degassing plays a significant role for soil solution chemistry even in Spodosol B and C horizons.

Methane uptake in soils of Southern Spain estimated by two different techniques: Static chamber and 222radon flux and soil air concentration profiles

Measurements of methane fluxes from four differing soils in the surroundings of Málaga (Spain) were carried out by two methods: a direct method using a static accumulation chamber at the soil surface and an indirect method obtained from simultaneously measured 222Rn flux from the soil surface in parallel with the concentration profile measurements of 222Rn and CH 4 in the air of soil. The directly measured methane flux at all the investigated soils was higher than the methane fluxes derived from the indirect method. Atmospheric methane was consumed by all the soils and mean direct flux to the atmosphere were 3.25 μmol m −2 h −1. The study showed no correlation between methane uptake and soil temperature, which might be due to the dry conditions prevailing during the study period.

High indoor radon variations and the thermal behavior of eskers.

Measurements of indoor radon concentrations in houses built on the Pispala esker in the city of Tampere were taken. The objective was to find connections between indoor radon concentrations, esker topography, and meteorological factors. The results show that not only the permeable soil but also subterranean air-flows in the esker strongly affect the indoor radon concentrations. The difference in temperature between the soil air inside the esker and the outdoor air compels the subterranean air to stream between the upper and lower esker areas. In winter, the radon concentrations are amplified in the upper esker areas where air flows out from the esker. In summer, concentrations are amplified in certain slope zones. In addition, wind direction affects the soil air and indoor radon concentrations when hitting the slopes at right angles. Winter-summer concentration ratios are typically in the range of 3-20 in areas with amplified winter concentration, and 0.1-0.5 in areas with amplified summer concentrations. A combination of winter and summer measurements provides the best basis for making mitigation decisions. On eskers special attention must be paid to building technology because of radon.

Relationships between field-measured denitrification losses, CO 2 formation and diffusional constraints

Approaches to quantify denitrification losses from arable land and other ecosystems are frequently hampered by the methods available. Extensive measurements of denitrification losses with the acetylene inhibition technique (AIT) over 3 years in various soils and crops (N 2O surface fluxes and soil air concentrations), when compared with simultaneously CO 2-production determinations, revealed that NO 3-respiration in well-aerated soils depends primarily on carbon and nitrate availability. N 2O concentrations in soil air exhibited significant correlations with soil depth, whereas the correlations between the N 2O soil air concentrations at 10cm depth and the N 2O soil surface fluxes were not significant. Increasing soil water contents reduced N 2O diffusion through the silty sand soil columns considerably, especially in the carbon-enriched upper 10cm. Denitrification losses ha −1, calculated from the N 2O concentrations in soil air and an assumed mean annual air-filled pore volume of about 20%, were higher than losses at the soil surface, suggesting that other soil variables besides carbon, nitrate and water availability are influencing N 2O + N 2 surface fluxes measured by the AIT. Soil processes controlling N 2O formation in the presence of C 2H 2 as well as the N 2O fluxes from the place of production to the soil surface are ranked and discussed.

222Rn flux and soil air concentration profiles in West-Germany. Soil 222Rn as tracer for gas transport in the unsaturated soil zone

222Rn flux and soil air concentration profiles in West-Germany. Soil 222Rn as tracer for gas transport in the unsaturated soil zone

<sup>222</sup>Rn flux and soil air concentration profiles in West-Germany. Soil <sup>222</sup>Rn as tracer for gas transport in the unsaturated soil zone

Measurements of the 222 Rn activity concentration profile in the soil and the 222 Rn flux in West-Germany are presented. The spatial pattern of the 222 Rn flux depends more on soil type than on the 226 Ra activity of the soil material. The average 222 Rn flux from sandy soils is 1000–2000 dpm m -2 h -1 and 4000–6000 dpm m -2 h -1 from loamy and clayey soils. Weekly 222 Rn flux measurements during a period of 1 year at a sandy site show no significant temporal variations. At a clayey site, the 222 Rn flux tends to be higher in summer than in winter. The permeability coefficient P Rn , obtained from simultaneous 222 Rn flux and concentration profile measurements in various soils, can be expressed as a function of the soil parameters total porosity ɛ 0 , soil moisture F , tortuosity k and the molecular diffusion coefficient D 0 of 222 Rn in air: P = D 0 (( ɛ 0 − F )/ k – const.). The flux of any other gas into or out of the soil can thus be calculated from its measured concentration profile in the soil and from the 222 Rn permeability coefficient, replacing the molecular diffusion coefficient of 222 Rn by that of the specific gas under consideration. As an example, this method of flux determination is demonstrated for the soil CO 2 flux to the atmosphere and for the flux of atmospheric CH 4 into the soil. DOI: 10.1034/j.1600-0889.1990.t01-1-00003.x

浅地層におけるＲａｄｏｎ‐２２２の動態

The concentrations and variation of 222Rn were investigated both in unconfined groundwater and in the aerated zone to obtain information as to the behavior of Rn close to ground surface.The Rn concentrations in unconfined groundwater near the surface were depletive by the extent of about 50% compared with that of lower part in a borehole, then the continuous extraction of groundwater causes pronounced increase of the concentration. The method, which monitors continuously the Rn concentration in such surroundings, was developed, where the unconfined groundwater extracted was injected into another borehole and sprayed gas was measured using an ionization chamber. The read-out values of this system well followed the variation of concentrations caused by the meteorological parameter, especially infiltrating water. The increase of 222Rn concentration in the aerated zone above the water level was clearly observed following the ascendant of groundwater level caused by the infiltrating water, whereas the change of concentration in soil air just below the ground surface obeyed mainly to the wetness of soil and unconfined groundwater level rather than atmospheric pressure.

Soil air carbon dioxide and oxygen measurements as a guide to concealed mineralization in semi-arid and arid regions

The differences between the CO 2 and O 2 concentrations in soil air and atmospheric air have been measured where sulfide mineralization occurs beneath transported exotic overburden in semi-arid and arid areas of the USA, South West Africa (Namibia) and Saudi Arabia. These mineralizations are reflected near surface by anomalous levels of CO 2 and O 2 in soil air, whereas in most cases heavy-metal anomalies are absent. The normal background variability of CO 2 and O 2 in soil air falls with increasing aridity, and anomaly definition improves with increasing aridity. Thus soil air CO 2 and O 2 data are potentially useful in exploring for concealed mineralization, especially in regions with an arid climate or conspicuous dry season.

Automatic monitoring of 22Rn daughter concentration in soil air by an electrode collector

A new 222Rn monitor is proposed. We discussed the automatic cyclic operation of counting the positively charged 222Rn daughter nuclides by GM counter after collecting them on the negatively charged electrode. The monitor was used to measure the variation of 222Rn concentration in the airspace of a ground-water storage tank and of a basement. The results clearly show that the 222Rn concentration has a negative cross-correlation with atmospheric pressure and a positive cross-correlation with air temperature.

Use of atmospheric fluorocarbons F‐11 and F‐12 to determine the diffusion parameters of the unsaturated zone in the Southern High Plains of Texas

Two stable, entirely man‐made fluorocarbon gases, trichlorofluoromethane (F‐1l) and dichlorodifluoromethane (F‐12), have been released into the atmosphere during the past 40 years as a consequence of their widespread commercial use. Production data for these compounds are well documented, and atmospheric buildup can be reconstructed on the basis of published release estimates. On‐site measurements of F‐1l and F‐12 concentrations in soil air within unconsolidated sedimentary deposits were made using gas chromatography at four sites in the Southern High Plains of Texas. Measurable concentrations of both gases were found at depths as great as 43.9 m. An analytical model and a finite‐difference model (both based on molecular‐diffusion theory) were used to assess the on‐site results. For the analytical model, effects of porosity, tortuosity, gas‐liquid partitioning, and sorption were tested as part of a lumped diffusion coefficient parameter. In the finite‐difference model, effects of porosity, tortuosity, and gas‐liquid partitioning were treated separately for individual layers, and sorption was treated as a single uniform parameter. Tortuosity values determined using the in situ measurement of F‐1l and F‐12 concentrations and the subsequent numerical modeling of results agree closely with values calculated using published theoretical and empirical relationships. These results thus confirm that the procedures for estimating tortuosity developed from theoretical considerations or by laboratory techniques are useful for predicting the transport of gases through even very thick and heterogeneous unsaturated zones. Such confirmation has not previously been available.

The occurrence of high CO 2, concentrations in soil air

The air composition was measured in soil columns with different textures. Carbon dioxide concentrations exceeding 40 volume percent were found above the capillary fringe in soil columns with stagnating water tables. As the clay content of the soil decreased, the level of maximum CO 2 concentration was found to occur at increasing depth below the surface. The very high CO 2 concentrations found are explained as being due to the release of CO 2 during evaporation of water, the high solubility of CO 2 in soil water and the high rate of microbiological activity.

The Responses of Molinia Caerulea and Erica Tetralix to Soil Aeration and Related Factors: II. Gas Concentrations in Soil Air and Soil Water

Previous studies (Sheikh 1969) described the growth of Molinia caerulea and Erica tetralix on some wet-heath sites at Bramshill Forest, Hampshire, which were described and named Valley-bog, Central associes, wetter Molinietum and drier Molinietum. Both species grew most slowly on the Valley-bog site, and best on the drier Molinietum. In the case of Molinia, differences of growth among sites appeared to be due to different nutrient conditions (see also Loach 1966) since the differences almost disappeared when nutrients were added to experimental plots. In the case of Erica tetralix, however, additional nutrients had no effect in overcoming the poor growth on the Valley-bog site and it was decided to investigate the aeration factor. This paper examines the variation of soil aeration, and related factors, at different depths and times on four sites, as a preliminary to controlled experiments on the significance of the aeration factor. Russell (1952) has emphasized the need of characterizing soil aeration by parameters that are of significance to plant growth. Parameters that describe, or allow the calculation of, conditions at the interface between the plant root and the soil system are an excellent means to this end. In soil, active plant roots are probably covered by a film of water. This is particularly true in the case of the roots growing in wet soils such as those studied in the present work. The concentration of gases at the root surface will depend upon the composition of the soil air, the transfer of gases across the gas-liquid interface, their diffusion across the liquid phase, and the rates of chemical and biological processes involving these gases in the soil. The effects of these various factors will be reflected in concentration gradients from the atmosphere above the soil to the root surfaces, first through the gaseous phase in the soil and then across the liquid phase. It would seem, therefore, that measurement of the concentration of gases in the liquid phase, although not identical with conditions at the root surfaces, does at least indicate these conditions better than the more widely employed analyses of samples of the gaseous phase. Studies on root distribution (Sheikh & Rutter 1969) showed that E. tetralix was a more shallow-rooting species than Molinia caerulea, but even in the latter about 950/ of the roots were found in the first 25 cm of soil on the sites studied. In view of this, analyses of gases in the soil were made mainly in the first 25 cm, although samples from 60 cm, i.e. below the permanent water-table, were also analysed.

Studies on the Effects of Soil Physical Conditions on the Growth and Yield of Crop Plants : VIII. Efects of aeration treatment on the nutrient absorption and tuberous root formation of sweet potato.

By managing so that a tuberous root forming place and a nutrient-absorbing place could be distinguished, the authors made these experiments to probe the effects of aeration treatment to each place and the amount of fertilizer (ammonium sulfate and potassium sulfate) on the growth of the top parts and the thickening of tuberous root. The results obtained may by summarized as follows. 1) The authors investigated the effects of aeration treatment in the soil where nutrient-absorbing chiefly took place, the condition of the soil where tuberous root was fomed being equal. As a result, it was observed that the growth of the top parts and the thickening of tuberous root were checked by the poor of the soil aeration and the soil compaction of a nutrient-absorbing place. However, when air was injected and O2 concentration in soil air was increased, the growth of the top parts and the thickening of tuberous root were remarkably promoted. On the other hand, when N gas was injected in that place and O2 concentration in soil air was decreased, the growth of non-tuberous root was promoted and the weight of the top parts increased, although the thickening of tuberous root was hampered and its weight decreased. When the soil of a nutrient-absorbing place was loose and the soil aeration was kept to be excellent, both the growth of the top parts and the thickening of tuberous root were greatly promoted and-the weight of tuberous root could be increased. 2) The authors examined the effects of fertilizer treatment to a tuberous root-forming place and a nutrient-absorbing place on the thickening of tuberous root. As a result, it was found that to apply much nitrogenous fertilizer (ammonium sulfate) promoted the growth of the top parts remarkably but hampered the thickening of tuberous root to some extent. On the other hand, to apply a great deal of potash fertilizer (potassium sulfate) hardly affected the growth of the top parts. but promoted the thickening of tuberous root and increased its weight. 3) The authors examined the effects of soil aeration to tuberous root-forming place on the growth of the top parts and the thickening of tuberous root, the condition of a nutrient-absorbing place being equal (in water culture). When N gas was injected in the soil and of concentration in soil air was decreased, the growth of the top parts was not affected so much, but the thickening of tuberous root was checked and its weight was decreased considerably.

Studies on the Effects of Soil Physical Conditions on the Growth and Yield of Crop Plants : VII. Effects of soil air composition and soil bulk density and their interaction on the growth of sweet potato

The authors made these experiments by growing sweet potato in Wagner's pot in order to probe the effects of soil air composition, soil bulk density and their interaction on the growth and yield of crops. Six treatments were made: two levels of soil air composition (the treatment where N gas was injected in the soil to decrease O2 concentration, and standard treatment), three levels of soil bulk density (loose, medium and compaction treatments), and their combination. The managing period was 42 days since the 76th day after planting when tuber-thickening stage of sweet potato (from August 23 to October 4). The results obtained may be summarized as follows. 1) As the soil became denser, total dry weight and the weight of tuberous root became smaller, and further the rate of the weight of tuberous root against total weight also decreased, which worsened the distribution of dry matter to the weight of tuberous root. However, the weight of the top parts and non-tuberous root was not affected so much by soil bulk density, and made little difference from that of the standard treatment. 2) When N gas was injected in the soil to decrease O2 concentration in soil air, total dry weight decreased in loose soil, but in the compact soil it was liable to be about the same as that of the standard treatment or to become somewhat greater. Whether the soil was compact or loose, tuberous root was hindered from thikening by N gas injection and decreased in production. It was found that the thickening of tuberous root was affected by soil air composition in the loose soil much more than in the compact soil. It was also observed that the rate of the weight of tuberous root against total weight was decreased by N gas injection treatment. On the other hand, the weight of the top parts and non-tuberous root was liable to become somewhat greater, probably because the thickening of tuberous root was checked by N gas injection treatment. 3) The authors examined the interaction of the effects of soil air composition and soil bulk density on the weight of tuberous root. As a result, it was found that when the soil was made compaction and further O2 concentration in siol air was decreased the thickening of tuberous root was hampered considerably and decreased in production. In this case, the effects of the decrease of O2 concentration in soil air were relatively small under the condition of compact soil.

Studies on the Effects of Soil Physical Conditions on the Growth and Yield of Crop Plants : V. Effects of Composition of soil air on the growth of crop plants.

When the O2 concentration in soil air decreased, the growth of crops was checked, but the effects were different according to the kinds of crops. In these studies the authors investigated the relationship between the N gas and O2 concentration in soil air and the growth of crops when it was cultivated in Wagner's pot. Sixteen kinds of crops were tested. The results obtained may be summarized as follows. Experiment 1 : Chiefly winter crops were tested. In examining the effects of the decrease of O2 concentration on the growth of crops, it was found that the growth of common vetch was significantly affected by the decrease of O2 concentration in soil air, and that the growth of oats was next to it. The growth of alfalfa, barly and wheat was found to make little differece from that of the standard treatment, and the growth of Italian ryegrass was somewhat better on the treatment where N gas was injected. Experiment 2 : Summer crops were tested. In examining the effects in question, it was found that the growth of peanut was significantly affected by the decrease of O2 concentration in soil air, and that the growth of sweet potato, maize and cucumber was also checked, whereas the growth of barnyard millet was somewhat better on the treatment where N gas was injected. Experiment 3 : The growth of every crop tested-upland rice, sorghum, soybean, Chinese cabbage and Japanese radish were checked by the decrease of O2 concentration in soil air. Above all, the growth of soybean and sorghum was inferior. Thus the effects which the decrease of O2 concentration in soil air had on the growth of crops were different depending on the kinds of crops. The effects in question were also different from one part of crops to another. For instance, in the case of sweet potato and Japanese radish the thickening of root aimed at a harvest was liable to be checked much more than any other part.

Studies on the Effects of Soil Physical Conditions on the Growth and Yield of Crop Plants : VI. Effects of Composition of soil air on the growth of crop in their different stages of growth.

These experiments were made to probe the effects of the composition of soil air on the growth of crops in their different stages of growth. Upland rice, soybean, sweet potato and maize were tested. The authors examined the effects of the decrease of the O2 concentration in soil air on the growth of crops in their early stage (from June 20 to July 10), in their middle growth stage (from July 10 to July 29), in their late growth stage (from July 29 to August 19), and in the ripening period of upland rice alone (from August 27 to October 7). In any crop, the check of dry matter production due to the decrease of O2 concentration in the soil air was found to be larger in its late growth stage when its growth was remarkable. However, when the rate of the increase of dry weight in the managing period in N gas injection treatment compared with that of standard treatment, the growth periods were different depending on the kinds of crops. The results according to the kinds of crops was as follows. (a) As to upland rice, its early stage of growth was largely affected by the decrease of O2 Concentration, and its growth in the managing period was liable to be hampered. Its ripening period was less affected than any other growth stage and the weight of grains was 98% of that of the standard treatment. (b) As to soybean, as the effects of treatment among its different growth stages was not so great, it was evident that the effects of O2 concentration was somewhat larger in later growth. (c) As to sweet potato, its late stage of growth was most largely affected by the decrease of O2 concentration and its growth was checked. Its early stage of growth was next to it, and its middle stage of growth was little affected. The effects of the composition of soil air on the weight of its tuberous roots was especially large. (d) As to maize, its late stage of growth was most largely affected by the decrease of O2 concentration, and its growth was checked. Its early stage of growth was next to it, and its middle stage of growth.