Understanding phosphorus mobility and bioavailability in the hyporheic zone of a chalk stream

Lapworth, Dan J.; Gooddy, Daren C.; Jarvie, Helen P.. 2011 Understanding phosphorus mobility and bioavailability in the hyporheic zone of a chalk stream. Water, Air and Soil Pollution, 218 (1-4). 213-226. 10.1007/s11270-010-0636-1

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Abstract/Summary

This paper investigates the changes in bioavailable phosphorus (P) within the hyporheic zone of a groundwater-dominated chalk stream. In this study, tangential flow fractionation is used to investigate P associations with different size fractions in the hyporheic zone, groundwater and surface water. P speciation is similar for the river and the chalk aquifer beneath the hyporheic zone, with ‘dissolved’ P (<10 kDa) accounting for ~90% of the P in the river and >90% in the deep groundwaters. Within the hyporheic zone, the proportion of ‘colloidal’ (<0.45 μm and >10 kDa) and ‘particulate’ (>0.45 μm) P is higher than in either the groundwater or the surface water, accounting for ~30% of total P. Our results suggest that zones of interaction within the sand and gravel deposits directly beneath and adjacent to river systems generate colloidal and particulate forms of fulvic-like organic material and regulate bioavailable forms of P, perhaps through coprecipitation with CaCO3. While chalk aquifers provide some degree of protection to surface water ecosystems through physiochemical processes of P removal, where flow is maintained by groundwater, ecologically significant P concentrations (20–30 μg/L) are still present in the groundwater and are an important source of bioavailable P during baseflow conditions. The nutrient storage capacity of the hyporheic zone and the water residence times of this dynamic system are largely

Item Type:	Article
Identification Number/DOI:	10.1007/s11270-010-0636-1
Programmes:	BGS Programmes 2010 > Groundwater Science CEH Topics & Objectives 2009 onwards > Water > WA Topic 2 - Ecohydrological Processes > WA - 2.1 - Identify and quantify sources, fluxes and pathways of water, chemicals ...
CEH Sections:	Acreman
ISSN:	0049-6979
Additional Keywords:	nutrients, phosphorus, hyporheic, groundwater, river, chalk, tangential flow, GroundwaterBGS, Groundwater, Environmental tracers, Groundwater quality, Surface water interaction fractionation (TFF)
NORA Subject Terms:	Ecology and Environment Hydrology
Date made live:	26 May 2011 09:43
URI:	http://nora.nerc.ac.uk/id/eprint/12789

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