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Tracing Sediment Sources in Eastern Iowa by Using Stable Carbon and Nitrogen Isotopes: An Exploratory Research
YEAR: 2003
INVESTIGATORS: Thanos Papanicolaou

Sediment fingerprinting via stable isotopes relies upon the premise that the physical and chemical properties of sediment will reflect its provenance. Sediments from different sources in most cases have different organic content (and in some cases different mineralogy) and as a result may exhibit different degree of impact in the receiving waters. The hypothesis in this exploratory research is that stable carbon and nitrogen isotope compositions coupled with measurements of carbon/nitrogen (C/N) ratios can be used to distinguish and quantify sources of sediments when all the factors affecting isotope spatial and temporal variability are considered. The sediment isotope fingerprinting method can be implemented successfully only if two conditions are met:(1) variation between sources must be greater than the variation within, and (2) any modification of the fingerprint due to anthropogenic and in-stream biogenic processes must be accounted for. The objectives of this research are to: (1) distinguish sediment sources by using isotopic ratios of 13C/12C or 15N/14N and atomic ratios of C/N in the Lower Cedar River Watershed; (2) evaluate the spatial and seasonal changes in the sources of sediments; and (3) explore the nature of the chemical and hydrological controls on the sources and composition of sediments.