Linking Nutrient Reactivity and Transport in Subsurface Flowpaths Along a Terrestrial-Estuarine Continuum

Salt marshes are critical “hot spots” of nutrient processing and retention and thus play an important role in improving coastal water quality. In particular, coastal salt marshes retain upwards of one-third of terrestrially derived nitrogen

nitrogen

Nitrogen, represented by the symbol N and atomic number 7, is a colorless, odorless, and tasteless gas that constitutes approximately 78% of Earth's atmosphere. It is vital for all life forms, as it is a fundamental part of amino acids, proteins, and DNA.

Source: Source

(N) loads, helping to mitigate negative environmental impacts such as eutrophication and harmful algal blooms. This removal is largely driven by sediment microbial activity, which is controlled by spatial and temporal variability in the availability in oxygen and organic matter. These changes in redox

redox

A chemical reaction that takes place between an oxidizing substance and a reducing substance. The oxidizing substance loses electrons in the reaction, and the reducing substance gains electrons.

Source: National Cancer Institue Source

characteristics and substrate availability impact the pathways by which N is processed by microbes.

microbe

Microbes are tiny living things that are found all around us and are too small to be seen by the naked eye. They live in water, soil, and in the air.

Source: NIH Source

Our study objective is to address a substantial knowledge gap in our understanding of the hydrologic and environmental factors that drive solute fate and transport at the subsurface terrestrial-marine boundary at tidal watershed

watershed

An area of land that channels rainfall and snowmelt to creeks, streams, and rivers, and eventually flows to the lowest point in a basin.

Source: USGS Source

mouths. At the Elkhorn Slough National Estuarine Research Reserve, we will couple field- and lab-based studies with reactive transport models to quantify the co-variation of hydrological and biogeochemical subsurface processes in coastal watersheds, with a particular emphasis on identifying drivers on N retention and removal over different hydrologic regimes. Through this effort, we are extending the DOE Scientific Focus Area testbed approach to a novel and underrepresented coastal ecosystem.

coastal ecosystem

Coastal habitats include estuaries, wetlands and marshes, coral reefs, kelp forests, tidepools, and barrier islands.

Source: USGS Source