Institute of Ecosystem Studies

2007 BES Annual Meeting Presentation and Poster Abstracts

Chemical composition, bioavailability, and ecological significance of organic nitrogen in urban streams
Delaney, Katie
Co-Authors: Katie Delaney and Sujay Kaushal
Abstract: Organic nitrogen comprises a substantial fraction of total N loads in streams and rivers and represents an emerging pollutant that contributes to problems such as eutrophication, harmful algal blooms and shifts in aquatic food webs in coastal waters. This study will relate the chemical composition of DON to bioavailability across a land use gradient from head waters to coastal waters and elucidate the sources and transformations of organic N. Samples will be taken bimonthly from streams in the BES draining urban, suburban and forested ecosystems. DON will then be analyzed for chemical composition by preparative scale column chromatography and mass spectrometry. Bioavailability will be determined using two methods: quantifying enzymatic activity and microbial biomass incubations. By examining the relationship between seasonal/temporal variations, measured chemical compositions and known biomarkers, such as lipids, relationships will be determined between specific forms of DON and bioavailability. In addition, chemical fingerprinting will be used to determine if the source of bioavailable DON is generated in stream or is coming from external watershed sources. This information will be useful in understanding the change in ecological significance of DON in aquatic ecosystems and its eutrophication potential. This knowledge can be applied to setting limits on amounts and forms of DON transported from headwaters to coastal environments.