Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2007
Publication Date: 11/1/2007
Citation: Haggard, B.E., Smith, D.R., Brye, K.R. 2007. Variations in Stream Water and Sediment Phosphorus among Select Ozark Catchments. Journal of Environmental Quality. 36:1725-1734. Interpretive Summary: Phosphorus (P) transport in streams can be impacted by the physiochemical properties of the sediments. For example, sediments can both remove P from the water column or release the bound P back to the water column, depending on the concentration of P in the water column. This study was conducted to: 1) evaluate the relationships between water chemistry and sediment in streams draining watersheds with various sizes and land uses; 2) to evaluate the relationships between soluble reactive P (SRP), sediment equilibrium P concentration (EPCo) and other abiotic factors; and 3) to assess the use of the Mehlich 3 soil extraction on stream sediments to determine factors that may control SRP concentrations in the water column. Stream water and sediment samples were collected from 22 Ozark streams in northwest Arkansas during Fall 2003 and Spring 2004. P saturation ratios (PSR) of benthic sediments increased with increasing percent pasture land use, whereas SRP and Mehlich 3 P concentrations decreased with increasing forest land use. Stream SRP concentrations were directly correlated with sediment EPCo, although EPCo values were typically greater than the SRP values. These data suggest that the sediments were controlling stream SRP concentrations by releasing P to the water column. The impact of this paper is to provide a resource to researchers and policy makers about how land use impacts nutrient transport in natural stream systems.
Technical Abstract: Stream sediments play a large role in the transport and fate of soluble reactive phosphorus (SRP) in stream ecosystems, and equilibrium P concentrations (EPC0) of benthic sediments at which P is neither adsorbed or desorbed are often related to stream water SRP concentrations. This study evaluated (1) the variation among water chemistry and sediment–P interactions among streams draining catchments that varied in the percent forested, pasture and urban land use; (2) the relations between SRP concentration, sediment EPC0 and other measured abiotic factors in the stream sediments; and (3) the use of the traditional M3 soil extraction on stream sediments to elucidate other abiotic factors related to SRP concentration in stream sediments. Stream water and sediments were sampled at 22 selected Ozark streams in northwest Arkansas during Fall 2003 and Spring 2004. NO3–N concentrations in the water column and modified P Saturation Ratios (PSRmod) of the benthic sediments at the selected streams increased with an increase in percent pasture land use in the catchments, whereas SRP concentration and Mehlich 3 P (M3P) content decreased with an increase the percent forested area. SRP concentrations in the stream water were positively correlated to sediment EPC0, although sediment EPC0 was generally greater than SRP. The use of the M3 soil extraction was useful in identifying abiotic factors related to SRP concentrations in streams, in particular SRP concentrations were positively correlated to M3P content and PSRmod of the benthic sediments at these selected streams. The impact of this paper is to provide a resource to researchers and policy makers about how land use impacts nutrient transport in natural stream systems.