Molecular Tracers of Organic Matter Sources to Surface Water Resources

TLDR

The study developed a molecular tracer method to identify organic matter sources to surface waters. The method targeted WWTP effluent, agricultural, feedlot, urban, suburban runoff, and wildlife, using fecal steroids, caffeine, fragrance materials, petroleum and combustion byproducts quantified by GC/MS, and compared tracer profiles from 19 watersheds to land‑use data. Significant correlations were found linking WWTPs to caffeine plus fragrance materials, agriculture to epicoprostanol, urban land‑uses to polycyclic aromatic hydrocarbons, and cholesterol in steroids shows promise as a wildlife tracer, demonstrating that molecular tracers effectively elucidate watershed‑scale contaminant sources.

Abstract

A molecular tracer method was developed for identifying organic matter sources to surface waters. We targeted wastewater treatment plant (WWTP) effluent, agricultural and feedlot runoff, urban and suburban runoff, and wildlife. Tracers included fecal steroids, caffeine, consumer product fragrance materials (FMs), and petroleum and combustion byproducts. The tracers were identified and quantified by gas chromatography/mass spectrometry. Organic matter sources were sampled directly and analyzed to identify a suite of compounds or ratios of compounds indicative of each source. Molecular tracer content of water samples collected from 19 watersheds was compared with land-use in those watersheds. Significant correlations were found between watershed scale land-use and tracers, such as WWTPs with caffeine plus FMs, agriculture with epicoprostanol content of steroids, and urban land-uses with the polycyclic aromatic hydrocarbons. The cholesterol content of steroids in samples holds promise as a tracer for wildlife. Molecular tracers were useful in elucidating sources of contaminants on a watershed scale.