Concepts

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

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

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

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

Geographic patterns in biodiversity and chemical diversity across latitudinal and environmental gradients

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

Acidic water containing elevated metal concentrations generated from oxidation of sulfide minerals in mining-disturbed areas

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

Properties of materials that inhibit microbial growth and decomposition

A transient pulse of CO₂ followed by a decrease to lower, steady state values when soils are rewet after a prolonged period of dry conditions

Areas where high rates of reactants are exported into receiving streams during hydrologic events

Poorly crystalline Fe oxyhydroxide mineral nanoparticles that are typically the first solid Fe oxyhydroxide phase to form upon oxidation of dissolved ferrous iron

Based on six membered planar hydrocarbon rings, such as benzene, coronene, or anthracene, known carcinogens that play a role in soot formation

Sharp redox gradients that favor the generation of ROS, created by mixing between waters with largely different chemical compositions

Non-majority spatially heterogeneous soil volumes possessing conditions differing from the bulk matrix, where internal oxygen consumption exceeds the rate of oxygen supply

Weathered bedrock zone between soil and unweathered bedrock that retains original rock structure

Loss of biodiversity and decreased soil nitrogen retention when nitrogen availability exceeds plant demand