A Review of the Hyporheic Zone, Stream Restoration, and Means to Enhance Denitrification

Abstract

The hyporheic zone is the subsurface area below and adjacent to a stream where groundwater mixes with stream water, through vertical, lateral, and longitudinal flows. The hyporheic zone connects the stream to uplands and other terrestrial environments. It is a zone of distinct faunal communities, high biological diversity and ecological complexity, and is the site of chemical processing and transformations of ground-and stream waters. The hyporheic zone is important to the overall ecosystem ecology of the stream, and it can influence stream water chemistry. Flows, reactions, and biota in the hyporheic zone are heterogeneous and patchy, making it difficult to clearly describe the ecotone in a straightforward, general way. Nitrogen processing, especially denitrification, appears to be widespread in the hyporheic zone. The hyporheic zone, as with most aquatic systems, is often impacted by human activities. Stream restorations rarely consider potential effects on the hyporheic zone, but careful project choices can enhance the condition of the hyporheic zone, and so increase uptake of nitrogen by stream-associated environments as partial mitigation of continuing and increasing releases of reactive nitrogen, potentially reaping short-term benefits to estuarine environments that might not be as quickly realized from source control measures.

Level and distribution of nutrients in the hyporheic zone of Lake Taihu (China) and potential drivers

“…In addition, potential biogeochemical processes driven by variable interior environments in the hyporheic zone due to upwelling or downwelling flow have often been reported (Ammar et al, ; Covino, ; Li et al, ; Siergieiev et al, ). In general, denitrification and anaerobic ammonia oxidation (Anammox) processes often occur in sediments under suboxic or anaerobic redox conditions (Merill & Tonjes, ; Trolle et al, ; Wang et al, ), which result in a loss of gaseous N. The three critical components favorable for denitrification (i.e., a potential source of nitrate, abundant organic carbon, and a suboxic redox environment) are usually present within the hyporheic zone (Briody, Cardenas, Shuai, Knappett, & Bennett, ) and mainly occur in deep sediments (Stelzer & Bartsch, ; Stelzer et al, ). Similarly, the dissimilatory nitrate reduction to ammonium (DNRA) process was also frequently reported in the hyporheic zone, which results in a decrease in and an increase in in the sediment (Nizzoli, Carraro, Nigro, & Viaroli, ).…”

The evolution and state of interdisciplinary hyporheic research

“…Extensive study of the hyporheic zone has generated understanding of a host of processes occurring within, giving rise to a number of useful functions . Hyporheic processes arise as a result of primary, interacting physical, chemical, and biological systems (Figure ) .…”

Yearlong Impact of Buried Organic Carbon on Nitrate Retention in Stream Sediments

“…If these conditions are present in groundwater‐dominated, nitrate‐rich streams, these systems can provide the ecosystem service of nitrate removal and retention. Management practices that promote natural deposition and burial of POC in streams at large spatial scales (Craig et al, 2008), thus providing opportunities for carbon‐facilitated nitrogen removal, and those that restore or protect groundwater–surface water interaction (Kasahara et al, 2009; Ward et al, 2011; Merill and Tonjes, 2014) may be more successful in achieving large‐scale reductions in downstream nitrogen fluxes than more invasive large‐scale carbon manipulation.…”