Groundwater redox conditions

Naudet, V., Revil, A., Rizzo, E., Bottero, J.Y. and Begassat, P. (2004) Groundwater redox conditions and conductivity in a contaminant plume from geoelectrical investigations. Hydrol. Earth Syst. Sci., 8(1), 8-22. 

Patterson CG, Runnells DD. 1992. Dissolved gases in groundwater as indicators of redox conditions. Water-Rock Interaction, Proc Int Symp, 7th 1 517-520. 

Radionuclide transport in natural waters is strongly dependent on sorption, desorption, dissolution, and precipitation processes. The first two sections discuss laboratory investigations of these processes. Descriptions of sorption and desorption behavior of important radionuclides under a wide range of environmental conditions are presented in the first section. Among the sorbents studied are basalt interbed solids, granites, clays, sediments, hydrous oxides, and pure minerals. Effects of redox conditions, groundwater composition and pH on sorption reactions are described. 

Procedures. Batch equilibrations of interbed solids (Mabton Interbed, Rattlesnake Ridge sandstone, or tuff), tracers, and groundwaters were used to measure radionuclide distributions between solid and liquid phases. Triplicate measurements were made for each combination of temperature, redox condition, tracer concentration, tracer type, groundwater composition, and interbed sample. Constant temperatures were maintained by placing the... 

Iron and manganese can have different oxidation states, depending on the redox conditions of the environment. Iron(II) compounds, however, are only stable under anaerobic conditions they transform iron(III) compounds on the effect of air and groundwaters (pH = 6-8), therefore, the interfacial processes of iron(II) oxides and hydroxide can play a smaller role under environmental conditions. (Note The iron(II) of silicates can also transform into iron(III) during weathering.)... 

U/ U ratios as tracers in springs and small streams, and these have mainly used uranium isotopes to trace the interaction of groundwater with surface water (e.g., Lienert et al., 1994). Lienert et al. (1994) attempted to link changes in uranium behavior to decreases in the anthropogenic inputs of phosphorous, which in turn affects biological activity and redox conditions within waters. As discussed in an earlier section of this chapter, the ratio has... 

Chapelle F. H. (1996) Identifying redox conditions that favor the natural attenuation of chlorinated ethenes in contaminated groundwater systems. In Symposium on Natural Attenuation of Chlorinated Organics in Ground Water, EPA/540/R-96/509, pp. 17-20. 

Christensen T. H., Bjerg P. L., Banwart S. A., Jakobsen R., Heron G., and Albrechtsen H.-J. (2000) Characterization of redox conditions in groundwater contaminant plumes. J. Contamin. Hydrol 45, 165-241. 

Surficial processes that affect the redox composition of Earth materials include weathering, drainage, groundwater movement, mechanical mixing and dispersion of rock material, soil formation, the accumulation of organic material and biological processes. There is an almost unlimited number of ways in which these factors can combine to affect the composition of Earth materials and therefore to affect local redox conditions. However, the processes that are most likely to affect redox locally can be simplified. 

Apart from biological uptake, denitrification in low-oxygen environments is the most important way that NO, is removed from soil, rivers and groundwater. It has been estimated that, in the rivers of northwest Europe, half of the total nitrogen input to the catchment is lost by denitrification before the waters reach the sea. Thus, under low redox conditions, DIP is mobilized during iron(EH) reduction and NOi is lost, again emphasizing the importance of redox processes in environmental chemistry. 

This relatively inoffensive example illustrates the importance of redox conditions in contaminated groundwater. Worse scenarios are known where toxic chlorophenolic compounds in very alkaline groundwaters (pH 10) ionize to neg-... 

---