MICROBIAL REDUCTION OF IRON IN SMECTITE (NONTRONITE), MIXED-LAYER SMECTITE/ILLITE, AND ILLITE: CORRELATING THE RATE AND EXTENT OF BIOREDUCTION WITH LAYER CHARGE AND EXPANDIBILITY

摘要

Clays and clay minerals are ubiquitous in soils, sediments, and sedimentary rocks. They play an important role in environmental processes such as nutrient cycling, plant growth, contaminant migration, organic matter maturation, and petroleum production. The changes in the oxidation state of the structural iron in clay minerals, in part, control their physical and chemical properties in natural environments, such as clay particle flocculation, dispersion, swelling, hydraulic conductivity, surface area, cation and anion exchange capacity, and reactivity towards organic and inorganic contaminants.