Phosphorus Retention in Riparian Buffers: Review of Their Efficiency

Abstract

Ground water and surface water interactions are of fundamental importance for the biogeochemical processes governing phosphorus (P) dynamics in riparian buffers. The four most important conceptual hydrological pathways for P losses from and P retention in riparian buffers are reviewed in this paper: (i) The diffuse flow path with ground water flow through the riparian aquifer, (ii) the overland flow path across the riparian buffer with water coming from adjacent agricultural fields, (iii) irrigation of the riparian buffer with tile drainage water from agricultural fields where disconnected tile drains irrigate the riparian buffer, and (iv) inundation of the riparian buffer (floodplain) with river water during short or longer periods. We have examined how the different flow paths in the riparian buffer influence P retention mechanisms theoretically and from empirical evidence. The different hydrological flow paths determine where and how water-borne P compounds meet and interact with iron and aluminum oxides or other minerals in the geochemical cycling of P in the complex and dynamic environment that constitutes a riparian buffer. The main physical process in the riparian buffer-sedimentation-is active along several flow paths and may account for P retention rates of up to 128 kg P ha(-1) yr(-1), while plant uptake may temporarily immobilize up to 15 kg P ha(-1) yr(-1). Retention of dissolved P in riparian buffers is not as pronounced as retention of particulate P and is often below 0.5 kg P ha(-1) yr(-1). Several studies show significant release of dissolved P (i.e., up to 8 kg P ha(-1) yr(-1)).

Efficiency of a constructed wetland for retention of sediment-associated phosphorus

“…Release of TP during high flow periods has often been observed in inflow/outflow studies of constructed wetlands receiving non-point source runoff (e.g. Reinelt & Horner, 1995;Braskerud, 2002;Hoffmann et al, 2009). Carleton et al (2001) reviewed data from 49 wetlands receiving storm water runoff and fitted both an areal P removal model (where the wetland volume is not included) and a volumetric model (where the detention time is used instead of the hydraulic load) to the data set.…”

“…4). Release of soluble P from sediment storage pools, resulting in recently restored wetlands acting as net sources of P has been observed but commonly when flooding agricultural soils rich in organic matter (reviewed by Reddy et al, 1999;Kadlec, 2005;Hoffmann et al, 2009). S. Stene was constructed on a mineral soil, and as much of the topsoil was removed there was little risk for release of mobile P from the soil.…”

“…In addition, considerable amounts of P would be removed; Hoffmann et al (2009) give values of 4-15 kg P/ha/yr in harvested biomass from wetlands. The timing and frequency of harvest must be properly chosen to sustain a high P uptake as studies have noted that frequent above-ground harvesting can slow the growth and biomass production of both T. latifolia and T. angustifolia (Sale & Wetzel, 1983;Jinadasa et al, 2008).…”

Phosphorus and Nitrogen Dynamics in Riverine Systems: Human Impacts and Management Options

“…Riparian areas constitute important interaction and buffer zones for river ecosystems as they control the fluxes of material and energy from the terrestrial catchment and the adjacent groundwater to the surface water (Hoffmann et al 2009). Floodplains and riparian areas have the ability to retain, transform, and release nutrients, thereby influencing the water quality of the recipient water body (Hoffmann et al 2009;Roberts et al 2012).…”

Modeling Phosphorus Capture by Plants Growing in a Multispecies Riparian Buffer

“…Paralleling the evolution of P transport models has been the development and implementation of various types of riparian buffers intended to retard the movement of P to surface waters [3,4]. Buffers can significantly reduce particulate P entering surface waters [5].…”