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Effluent organic nitrogen (EON): bioavailability and photochemical and salinity-mediated release
Deborah A Bronk1, Quinn N Roberts, Marta P Sanderson
1Virginia Institute of Marine Science, The College of William & Mary, Gloucester Point, Virginia 23062, Old Dominion University, Norfolk, Virginia 23529, USA. bronk@vims.edu
Environmental Science & Technology
|July 2, 2010
Summary
Wastewater effluent organic nitrogen (EON) can be removed by biological processes and sunlight. Higher salinity releases ammonium from EON, contributing to coastal eutrophication.
Area of Science:
- Environmental Chemistry
- Marine Biology
- Water Quality
Background:
- Wastewater treatment plant (WWTP) effluents contain effluent organic nitrogen (EON), a potential contributor to coastal eutrophication.
- Understanding EON's fate in marine environments is crucial for managing coastal water quality.
Purpose of the Study:
- Investigate three pathways of EON contribution to coastal eutrophication: biological removal, photochemical release, and salinity-mediated ammonium release.
- Assess the influence of salinity on EON transformation and nutrient cycling.
Main Methods:
- Collected WWTP effluents and estuarine water from the James River at various salinities.
- Conducted bioassays over 48 hours measuring nitrogen and phosphorus compounds.
- Exposed EON to sunlight to assess photoreactivity and ammonium release.
Main Results:
- Some EON was biologically removed, with removal rates varying by effluent type and salinity.
- EON demonstrated photoreactivity, releasing labile ammonium and dissolved primary amines upon sun exposure.
- Increasing salinity significantly increased ammonium release from EON.
Conclusions:
- EON can be transformed through biological and photochemical processes in coastal waters.
- Salinity plays a critical role in releasing bioavailable ammonium from EON as it moves from freshwater to marine environments.
- These findings highlight EON as a significant nutrient source contributing to coastal eutrophication.
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