Soil gas concentrations

Concentrations of hydrogen sulfide in soil gas from samples taken at some NPL sites ranged from 75 to 47,000 ppm (HazDat 1997). Data on soil gas concentrations at all NPL sites were not available. 

The internal walls between the scullery and the office and between the kitchen and the sitting room descended below the base of the concrete floor to the sub-soil. Clearly, the effectiveness of the suction systems in reducing the soil gas concentration at the base of the walls was limited because of the distance from the suction points. 

Radon in soil gas is present everywhere throughout the province in all geologic terrains. Soil gas Rn concentrations range from a low of 0.1 kBq/m3 to a high of 207.0 kBq/m3 with a mean of 25.3 kBq/m3 (Fig. 3). The highest Rn soil gas concentrations are also associated with Middle-to-Late Devonian leucomonzogranite of the South... 

Kraner, A.W., Schroeder, G.L. Evans, R.D. (1964) Measurements of the effects of atmospheric variables on radon-222 flux and soil gas concentrations. In The Natural Radiation Environment, ed. J. A.S. Adams W.M. Lowder, University of Chicago Press, pp. 191-215. 

In geochemical exploration, soil samples, either surficial or (in arid regions) microlayer are the recommended sample medium for the collection of sulphur compounds in soil gases. Soils should be placed in plastic bags or glass containers that are as air-tight as possible. An entire study area should be sampled at one time, over a period of as few days as possible, to avoid weather-related or seasonal fluctuations in soil-gas concentrations. The soil samples should be stored in a cool place or in a freezer. All of the soil samples from a particular area should be analysed as quickly as possible after collection. They should be sieved to the same mesh size and should be of the same weight for analysis. 

The highest He concentrations reported for probe sampling were found at the Ambrosia Lake district. New Mexico, USA, in a restricted survey of 46 samples from a 1.2 x 3.2 km area over mineralisation 300-400 m deep (Reimer et al., 1979b). The mean soil-gas concentration was 5.30 ppm He, with three samples containing 5.47-5.65 ppm He. The distribution pattern has some coherence but is not readily related to the location of the mines and has probably been affected by the mining operations. 

Figure 3. Normalized soil gas concentrations for propargyl bromide in (A) mesocosm receiving ATS solution and (B) mesocosm receiving water only (no ATS) at 52 hours after ATS/water application. Points indicate locations of soil gas samples. To aid in visualization, concentrations in the other half of the bed are indicated by the contours, assuming a symmetric distribution.

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