Benthic sediment influence on dissolved phosphorus concentrations in a headwater stream

Abstract

Phosphate interacts with inorganic sediment particles through sorption reactions in streams. Collectively, this phosphorus (P) buffering mechanism can be an important determinant of soluble reactive P (SRP) concentrations. If sorption reactions control SRP concentrations in a stream, then differences in sediment characteristics may cause spatial differences in SRP concentrations. This prediction was tested by examining sediment-buffering characteristics and spatial variation in SRP among reaches with distinct sediment composition (i.e., fine versus coarse particles) in two tributaries of Boulder Creek, a headwater stream in central Wisconsin. SRP concentrations were significantly lower and algal available P and P sorption capacity were significantly higher in the reach dominated by fine sediments. Although fine particles such as sand had the greatest P sorption capacity, no retention could be attributed to biotic processes, whereas over 50% of P retention in coarse particles such as gravel could be linked to biotic uptake. Equilibrium P concentration (EPC 0 ) assays from different sediment fractions also indicate that biotic uptake is relatively unimportant in sand particles (EPC live 10 mg/L: EPC killed 10 mg/L) but very important in gravel or larger particles (EPC live 10 mg/L: EPC killed 80 mg/L). Thus, sediment influence on stream water P concentrations can shift predictably from abiotic sorption in reaches with fine particles to biotic retention in areas dominated by coarse sediments. Consequently, changes in sediment composition due to natural or anthropogenic disturbance have the potential to alter the type and strength of sediment-associated processes determining ambient stream P concentrations.

Variation in summer nitrogen and phosphorus uptake among Siberian headwater streams

“…One hypothesis for this observation is simply P limitation of floodplain streams, as has been observed in the Alaskan tundra (Peterson et al 1985;Slavik et al 2004). Alternatively, this pattern may be the result of high physical sorption of P (Lottig & Stanley 2007) and low biological uptake of nutrients in floodplain streams relative to upland streams. Results of sorption experiments support this conclusion, suggesting that biological uptake of P in upland streams is threefold higher than in floodplain streams and that nearly all P uptake in floodplain streams was explained by physical processes (ca.…”

“…It seems quite likely that increasing organic matter and nutrient inputs will stimulate biological activity to a greater degree than physical processes (Lottig & Stanley 2007), which may lead to larger changes in organic matter and nutrient dynamics in upland streams. This may result in very different spatial and temporal patterns in nutrient export downstream.…”

“…Physical sorption of P in sediments from the five study streams was estimated following protocols outlined by Lottig & Stanley (2007). At each stream, five sediment samples were collected along a longitudinal transect at 1 m intervals.…”

Within-River Phosphorus Retention: Accounting for a Missing Piece in the Watershed Phosphorus Puzzle

“…At both Siloam and Tahlequah, within-river retention of effluent TP dropped dramatically (by a factor of c. 9) after 2002, as a result of enhanced nutrient removal at Springdale WWTP and the resulting reductions in effluent P input loading. Earlier studies have suggested that P uptake by periphyton exerts a major control on withinriver P retention in the Illinois River 54 . The decline in P retention with decreasing effluent P load also suggests a biological control mechanism: reductions in effluent P inputs may reduce the periphyton biomass that can be supported, thus leading to a decline in P retention.…”

Nutrient Content at the Sediment-Water Interface of Tile-Fed Agricultural Drainage Ditches

“…The transport and storage of P in drainage ditches involve complex biogeochemical processes [3,10]. Of all the components that affect nutrient dynamics and transport in aquatic ecosystems, benthic sediments are probably the most influential determinant of the ability of the system to process and sustain nutrient loads, especially P [7,11,12]. Sediments play an active role in inorganic P uptake and may potentially control P concentrations in the overlying water column [1,12,13].…”