Cross System Comparison of Oxygen Effects on Nitrogen Cycling in Tidal Sub-Estuaries of Patapsco River

Principal Investigator:

Jeremy Testa

Start/End Year:

2018 - 2019


Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science

Co-Principal Investigator:

Fellow: Drew Hobbs

Strategic focus area:

Healthy coastal ecosystems


Rock Creek is a tidal tributary to the Patapsco River in Anne Arundel County, Maryland and has historically had poor water quality including the development of water-column anoxia. An aeration system was installed into the creek in 1988 to help alleviate the water quality problems. Several recent studies have been conducted on the creek in order to view how aeration affects sediment nitrogen and oxygen fluxes, but less emphasis was placed on the associated production of problematic compounds. For example, with the establishment of anoxia hydrogen sulfide (H2S) is released from anoxic sediments, which can inhibit nitrification and negatively impact other aquatic life. Alterations of nitrogen cycling in low-oxygen environments can also lead to elevated production of the greenhouse gas nitrous oxide (N2O) as a byproduct of the transformation of nitrate (NO3-) to N2 gas. Measuring and quantifying N2O concentrations within an aquatic system can provide insight into the rates of denitrification that may be occurring, as well as the availability of the gas in nutrient enriched waters. Thus, I propose to measure the concentrations of H2S and N2O, nitrogen concentrations, and sediment-water fluxes of oxygen and nitrogen during September 2018 and spring 2019. These measurements will be made in the aerated Rock Creek, as well as two adjacent creeks (Stoney Creek and Bodkin Creek) that have never been studied despite their immediate proximity to Rock Creek, lack of aeration, and potential for similarly oxygen-depleted conditions. These surveys will provide useful and relevant data to help (a) better understand the impacts of engineered aeration of coastal systems, (b) investigate the potential for sulfide accumulation to alter nitrogen cycling, and (c) improve our understanding of N2O availability in Chesapeake Bay.

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