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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #333467
Title: Climate change effects on phosphorus uptake by stream bed sediments

Author
item MCDOWELL, RICH - Agresearch
item Elkin, Kyle
item Kleinman, Peter

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2016
Publication Date: 3/17/2017
Citation: Mcdowell, R., Elkin, K.R., Kleinman, P.J. 2017. Climate change effects on phosphorus uptake by stream bed sediments. Journal of Environmental Quality.46:295-301. doi:10.2134/jeq2016.09.0352.

Interpretive Summary: Phosphorus (P) is a leading cause of water quality degradation in impaired fresh water systems. Although substantial progress has been made in understanding the fate and transport of P, the effects of a changing climate are relatively unknown. Stream bed sediments which serve as both a source and sink for P were investigated to see how increased stream temperatures effect their ability to sequester P in solution; commonly seen in agricultural runoff. Our research suggests that in fact, higher temperatures have a detrimental effect on the ability of both biotic and abiotic processes to remove P from streams. Thus strategies to mitigate P losses from land to water could have a more significant benefit in warming climates.

Technical Abstract: Climate change will likely increase growing season temperatures and the ratio of nitrogen (N) to phosphorus (P) loss from land to water. However, it is unknown how these factors influence the uptake of P or likely P-limitation of algal growth 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 maintained at 19 or 26oC. Water and sediment samples were taken with time since runoff was introduced. A greater magnitude and rate of P uptake by sediments was noted at 19oC compared to 26oC, and with sediment with N added compared to sediment without added N. Analysis of sediment samples indicated that P uptake via abiotic processes was greater at 19oC than 26oC. The addition of N stimulated P uptake by the microbial biomass, but microbial uptake was inhibited at 26oC. 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 algal growth.