title: Temperature and Nitrogen Effects on Phosphorus Uptake by Agricultural Stream-Bed Sediments.
abstract: Climate change will likely increase the growing season, temperatures, and ratio of nitrogen (N) to phosphorus (P) loss from land to water. However, it is unknown how these factors influence P concentrations in streams. We sought to evaluate differences in biotic and abiotic processes affecting stream sediment P dynamics under different temperature and N-enrichment regimes. Three sediments of varying P composition and sorption characteristics were placed into a fluvarium. Synthetic runoff water, with or without added N, was added to the flume's reservoir, and the solution was maintained at 19 or 26°C. Water and sediment samples were taken with time since runoff was introduced. The rate and magnitude of P uptake by sediment was greater at 19°C compared with 26°C, and also when N was added compared with no N added. Analysis of sediment samples indicated that P uptake via abiotic processes was greater at 19 than at 26°C. The addition of N stimulated P uptake by the microbial biomass at 19°C, but microbial uptake was potentially inhibited at 26°C. Because microbial biomass is a temporary store of P, these data suggest that more P may be available with increasing temperatures during the growing season, especially under baseflow, implying that strategies to mitigate P losses from land to water should be strengthened to prevent potential water quality impairment.
authors.forename: Richard W
authors.initials: RW
authors.lastname: McDowell
authors.forename: Kyle R
authors.initials: KR
authors.lastname: Elkin
authors.forename: Peter J A
authors.initials: PJ
authors.lastname: Kleinman
mesh_terms: D019015:Geologic Sediments; D009584:Nitrogen / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry*; D045483:Rivers; D013696:Temperature
chemical_list: D010758:Phosphorus; D009584:Nitrogen