Concepts

Removal of nitrate from porewater through denitrification and other biogeochemical processes

Microbially-mediated oxidation of organic matter consuming oxygen and producing CO2 that controls oxygen availability in subsurface environments

Oxidative dissolution of pyrite mineral producing sulfuric acid and iron oxides under oxic conditions

The preferential incorporation of lighter or heavier isotopes during physical and biological processes, recorded in tree cellulose

Microbial process where methane is oxidized under anoxic conditions, often coupled to reduction of alternative electron acceptors

Constraint on growth or reproduction due to insufficient availability of essential nutrients

The contribution of animals to ecosystem nutrient fluxes through excretion, with supply determined by animal biomass, excretion rates, and time spent in the ecosystem

The oxidation of ammonia to nitrate via nitrite, linking nitrogenous organic matter remineralization to nitrogen loss processes in the microbial N-cycle

Chemical and physical breakdown of sedimentary shale rocks through interactions with water, atmospheric gases, and biological processes

Spatial organization of aerobic and anaerobic zones based on dissolved oxygen availability that controls biogeochemical reactions

Biogeochemically active zones in riparian floodplains where enhanced nitrogen transformations occur due to groundwater-surface water interactions

The interplay of belowground, microsite-scale biological, physical, and chemical processes that intersect to drive whole-ecosystem functioning

The constraint of microbial activity and carbon respiration by water availability in soil systems

Microbial reduction of sulfate coupled to organic matter oxidation in anoxic environments resulting in formation of low solubility sulfide minerals

The cycling of iron between different chemical forms including soluble ferrous iron (Fe(II)) and ferric iron (Fe(III)) based on oxygen availability

Formation of coordination complexes between Fe(II) ions and natural organic matter ligands

Rate laws governing the chemical breakdown of primary minerals as functions of temperature, pH, and saturation state