Microbial activities in soil near natural gas leaks

A Facility to Investigate Effects of Elevated Soil Gas Concentration on Vegetation

“…Hence the bacteria tend to be confined to fairly narrow horizontal bands within their habitat, limited in their distribution by the downward diffusion of atmospheric O 2 and the upward diffusion of CH 4 . Methane oxidising activity, with a decrease in soil O 2 and an increase in soil biomass, has been demonstrated around leaks in natural gas pipes (Adams and Ellis, 1960;Adamse et al, 1972). Arthur et al (1985), Gilman et al (1982) and Hoeks (1972b) found that elevated CH 4 concentrations were associated with depleted O 2 of between 0 and 12% and elevated CO 2 concentrations of up to 35% in the soil atmosphere.…”

“…It has been suggested that leaking natural gas causes stress to vegetation because the gas displaces O 2 from the soil (Hoeks, 1972;Arthur et al, 1985;Smith, 2002), thus inhibiting root respiration that provides energy for root growth and uptake of water and nutrients from the soil. Adamse et al (1972) suggested that for the proper functioning of a healthy root system, a minimum O 2 content of the soil atmosphere of 12-14% is needed.…”

“…Adamse et al (1972) suggested that for the proper functioning of a healthy root system, a minimum O 2 content of the soil atmosphere of 12-14% is needed. Hoeks (1972a) found almost zero O 2 concentrations, and CO 2 concentrations of up to 14%, in soil near a gas leak.…”

Gas simulation models for solid waste landfills

“…Although shortlived, aerobic processes are highly exothermic, and, hence, they are accompanied by the release of a substantial amount of heat, which may cause a rise in landfill temperatures by as much as 30T higher than surrounding temperatures. 171 (1) While oxygen depletion proceeds at a faster rate than it is replenished, air diffusion continues to provide oxygen to the upper layers near the ground surface where it is readily consumed by aerobic bacteria. This explains the higher than ambient temperatures observed near the ground surface even in sanitary landfills located in cold regions.…”

“…Although the data presented in Tables 4 and 5 are derived primarily from wellcontrolled anaerobic digestion studies, their relevancy to landfills is twofold: (1) in light of the difficulty associated with obtaining such data from actual landfills, they can be used as guidance to estimate microbial growth constants in models that adopt the concept of a landfill acting as a batch bioreactor because sequential biodégradation processes are similar in both environments; (2) they serve as a benchmark in selecting parameter variation when conducting a sensitivity analysis. Note that some of the values of yield coefficients and specific growth rate constants are based on thermodynamic and electron-transfer considerations, 118 -119 which are substantiated by comparable experimental results, 152 whereas half-saturation and decay rate constants are based only on experimentally determined values.…”