Concepts

Human-induced nitrogen input that has doubled biologically-available nitrogen on Earth

Major form of organic carbon across aquatic ecosystems, fueling stream metabolism and mediating key biogeochemical processes

Removal of nitrate from porewater through denitrification and other biogeochemical processes

Organic carbon derived from sedimentary rocks that is often poorly quantified and influences soil organic carbon composition, age, and stability

Modeling approach that couples transport processes with geochemical reactions to understand subsurface flow and chemical interactions

Spatial variability in biogeochemical processes and solute sources within watersheds, particularly between shallow soil zones and deeper groundwater zones

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

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

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

Areas of disproportionately high biogeochemical activity or export relative to surrounding landscape

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

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

Spatial variations in oxidation-reduction conditions within floodplain environments that can form within microsites, along textural transitions, or along the capillary fringe

The association of uranium with different solid-phase mineral forms that influences uranium mobility between solid and water phases

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

Vertical distribution of plant nutrient uptake from soil surface through saprolite to bedrock

Zone of active mineral dissolution and precipitation reactions that advances through bedrock over time