title: Characterizing the oxygen isotopic composition of phosphate sources to aquatic ecosystems.
abstract: The oxygen isotopic composition of dissolved inorganic phosphate (delta18Op) in many aquatic ecosystems is not in isotopic equilibrium with ambient water and, therefore, may reflect the source delta18Op. Identification of phosphate sources to water bodies is critical for designing best management practices for phosphate load reduction to control eutrophication. In order for delta18Op to be a useful tool for source tracking, the delta18Op of phosphate sources must be distinguishable from one another; however, the delta18Op of potential sources has not been well characterized. We measured the delta18Op of a variety of known phosphate sources, including fertilizers, semiprocessed phosphorite ore, particulate aerosols, detergents, leachates of vegetation, soil, animal feces, and wastewater treatment plant effluent. We found a considerable range of delta18Op, values (from +8.4 to +24.9 per thousand) for the various sources, and statistically significant differences were found between several of the source types. delta18Op measured in three different fresh water systems was generally not in equilibrium with ambient water. Although there is overlap in delta18Op values among the groups of samples, our results indicate that some sources are isotopically distinct and delta18Op can be used for identifying phosphate sources to aquatic systems.
authors.affiliation: US. Geological Survey, Menlo Park, California 94025, USA. mbyoung@usgs.gov
authors.forename: Megan B
authors.initials: MB
authors.lastname: Young
authors.forename: Karen
authors.initials: K
authors.lastname: McLaughlin
authors.forename: Carol
authors.initials: C
authors.lastname: Kendall
authors.forename: William
authors.initials: W
authors.lastname: Stringfellow
authors.forename: Mark
authors.initials: M
authors.lastname: Rollog
authors.forename: Katy
authors.initials: K
authors.lastname: Elsbury
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Donald
authors.forename: Adina
authors.initials: A
authors.lastname: Paytan
mesh_terms: D017753:Ecosystem; D005068:Eutrophication; D005618:Fresh Water; D010103:Oxygen Isotopes / Q000032:analysis*; D010710:Phosphates / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry; D014865:Waste Disposal, Fluid; D014873:Water Pollutants / Q000032:analysis*; D014881:Water Supply / Q000032:analysis
chemical_list: D010103:Oxygen Isotopes; D010710:Phosphates; D012722:Sewage; D014873:Water Pollutants