Retention and Transport of Nutrients in a Third-Order Stream in Northwestern California: Hyporheic Processes

Abstract

Chloride and nitrate were coinjected into the surface waters of a third-order stream for 20 d to examine solute retention, and the fate of nitrate during subsurface transport. A series of wells (shallow pits) 0.5-10 m from the adjacent channel were sampled to estimate the lateral interflow of water. Two subsurface return flows beneath the wetted channel were also examined. The conservative tracer (chloride) was hydrologically transported to all wells. Stream water was > 88% of flow in wells < 4 m from the wetted channel.The lowest percentage of stream water was 4 7% at a well 10 m perpendicular to the stream. Retention of solutes was greater in the hyporheic zone than in the channel under summer low-flow conditions. Nominal travel time (the interval required for chloride concentration to reach 50% of the plateau concentration) was variable by well location, indicating different flow paths and presumably permeability differences in subsurface gravels. Nominal travel time was <24 h for wells <5 m from the wetted channel. Coinjected nitrate was not conservative. Two wells were significantly (P < .05) higher in nitrate-N than would be predicted from chloride, while four were significantly lower. Wells 2.0-4.0 m from the wetted channel tended to have higher nitrate concentration than predicted, whereas nitrate sink locations tended to have transport distances >4.3 m. The capacity of the hyporheic zone for transient solute storage and as potential biological habitat varies with channel morphology, bed roughness, and permeability. A conceptual model that considers the groundwater-stream water interface as the fluvial boundary is proposed. Emerging paradigms of the riverine network should consider the hyporheic zone and associated nutrient cycling as an integral component of fluvial structure and function.

Spatial patterns of hyporheic exchange and biogeochemical cycling around cross‐vane restoration structures: Implications for stream restoration design

“…[2] The hyporheic zone is the area of the streambed and banks where water from the active channel mixes with sediment pore water and returns to the channel [Triska et al, 1989;White, 1993;Harvey and Wagner, 2000;Gooseff, 2010]. Channel bed morphologies, such as steps, pools, and riffles, intensify the vertical flux of water through the hyporheic zone by a variety of hydraulic mechanisms [Elliott and Brooks, 1997;Hester and Doyle, 2008;Buffington and Tonina, 2009;Tonina and Buffington, 2009;Endreny et al, 2011a].…”

Hyporheic Flows Along a Channelled Peatland: Influence of Beaver Dams

“…Hyporheic flow is the exchange of groundwater and stream water across the stream bed and banks (Triska et al, 1989). Hyporheic zones are temporally and spatially dynamic (Harvey and Wagner, 2000) and many researchers have investigated hyporheic exchange because of its influence on the biogeochemical and ecological functioning of stream ecosystems (e.g.…”

Tracer Additions for Spiraling Curve Characterization (TASCC): Quantifying stream nutrient uptake kinetics from ambient to saturation

“…This area of research has expanded as N loading to terrestrial and aquatic ecosystems has increased (Vitousek et al 1997;Turner and Rabalais 2003), and concerns over deleterious impacts on receiving water bodies have grown (Rabalais et al 2009). Stream reach nutrient export is impacted by both biological (i.e., uptake) and physical (i.e., hydrologic loss) retention (Triska et al 1989;Hart et al 1992;Covino et al 2010), and research has shown that in-stream uptake (i.e., biological retention) can be strongly influenced by nutrient concentration (Dodds et al 2002;Earl et al 2006;O'Brien et al 2007). The relationship between biological uptake and nutrient concentration is of particular concern because nutrient uptake efficiency has been shown to decrease with elevated concentrations (Mulholland et al 2002).…”