Microbial conditions, ground water

Figure 14.3 Variation in concentrations of important dissolved redox species along the flowpath of a contaminant plume in ground-water. This sequence results in several zones of characteristic microbial metabolism and corresponding redox conditions (adapted from Bouwer et al., 1984).

Paraquat is relatively immobile in soil. Paraquat resists hydrolysis, photodegradation in water, and microbial degradation under both aerobic and anaerobic conditions. Dissipation is primarily by adsorption to organic material and clay particles. As paraquat persists in clay soils, it may be found in surface water from erosion. Since it binds so strongly to clay particles, paraquat is not generally a ground-water concern. 

If quinoline is released into water it will degrade dependent on the temperature and microbial conditions. Complete degradation can be expected to occur in less than a week. If ground soil is contaminated with quinoline, it will quickly partition to groundwater. Less than 0.5% of the quinoline will be expected to remain in the soil. 

Data from field and laboratory studies of creosote-contaminated ground water are being analyzed by the U S. Geological Survey to determine the transformation pathways of selected organic compounds, assess the relative importance of physical, chemical, biochemical, and microbial processes in the transformation of these compounds under ambient conditions, and study relevant biotransformation processes occurring in the subsurface ground water. 

The ground-water environment is quite variable in its physical conditions of ground-water distribution, occurrence and flow. What was considered a sterile environment, devoid of oxygen, is known to contain dissolved oxygen and considerable microbial biomass (1). Distributions of... 

---