Chemical Export to River Systems from the Critical Zone

There is a growing recognition that the Critical Zone, extending from shallow soils to deeper permeable bedrock, is an important source of chemical constituents that make their way into river systems, thus exercising a primary control on water quality. Chemical fluxes to river systems may originate in soils, where various plant and carbon-mediated physical and biogeochemical processes are expected to dominate, or from weathering of bedrock (saprolite) in the shallow Critical Zone where rock forming minerals dissolve, to the deeper Critical Zone where flow paths with long travel times may produce more concentrated solutions high in metals, anions, and cations. All of these compartments within the Critical Zone are expected to export solutions to rivers within watersheds, and their relative contribution is expected to change due to seasonal and longer-term transients.
In this Research Topic, we seek manuscripts on the topics of characterization, experimental, and modeling studies of the chemical export from the Critical Zone, with a focus on those most important in determining water quality. Example topics of interest include: the role of plants in regulating weathering and consequent chemical export, transients versus steady-state behavior, and processes that control variations in aqueous phase (classical chemical weathering) and solid phase transport (erosion processes).
For this Research Topic, submissions focused on plant-related chemical processes, chemical weathering, surface and subsurface water flow and consequent chemical export, and diurnal versus seasonal effects are encouraged, but all kinds of research studies where an important control on river quality traced back to the Critical Zone are invited. Characterization and experimental studies may be based on any number of approaches, and may range in scale from the micro-scale to the watershed scale. Theoretical or methodological advances may include reactive transport modeling, integrated surface-subsurface hydrological modeling, and machine learning.
The following article types are available: Original Research, Mini Review, Opinion, Review, Technology and Code, Brief Research Report, Conceptual Analysis, Perspective and Methods.