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Characterizing the oxygen isotopic composition of phosphate sources to aquatic ecosystems

M.B. Young·K. McLaughlin·C. Kendall·W. Stringfellow·M. Rollog·K. Elsbury·E. Donald·A. Paytan
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Abstract

The oxygen isotopic composition of dissolved inorganic phosphate (δ 18 O p ) in many aquatic ecosystems is not in isotopic equilibrium with ambient water and, therefore, may reflect the source δ 18 O p . Identification of phosphate sources to water bodies is critical for designing best management practices for phosphate load reduction to control eutrophication. In order for δ 18 O p to be a useful tool for source tracking, the δ 18 O p of phosphate sources must be distinguishable from one another; however, the δ 18 O p of potential sources has not been well characterized. We measured the δ 18 O p 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 δ 18 O p values (from +8.4 to +24.9‰) for the various sources, and statistically significant differences were found between several of the source types. δ 18 O p measured in three different fresh water systems was generally not in equilibrium with ambient water. Although there is overlap in δ 18 O p values among the groups of samples, our results indicate that some sources are isotopically distinct and δ 18 O p can be used for identifying phosphate sources to aquatic systems.

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M.B. Young, K. McLaughlin, C. Kendall, W. Stringfellow, M. Rollog, K. Elsbury, E. Donald, A. Paytan. 2009-06-10. Characterizing the oxygen isotopic composition of phosphate sources to aquatic ecosystems. https://doi.org/10.1021/es900337q

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