Water, Air, & Soil Pollution

, Volume 218, Issue 1, pp 213–226

Understanding Phosphorus Mobility and Bioavailability in the Hyporheic Zone of a Chalk Stream

  • Dan J. Lapworth
  • Daren C. Gooddy
  • Helen P. Jarvie
Article

DOI: 10.1007/s11270-010-0636-1

Cite this article as:
Lapworth, D.J., Gooddy, D.C. & Jarvie, H.P. Water Air Soil Pollut (2011) 218: 213. doi:10.1007/s11270-010-0636-1

Abstract

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 co-precipitation 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 unknown and warrant further investigation.

Keywords

Nutrients Phosphorus Hyporheic Groundwater River Chalk Tangential flow fractionation (TFF) 

Copyright information

© Springer Science+Business Media B.V. / British Geological Survey-NERC 2010

Authors and Affiliations

  • Dan J. Lapworth
    • 1
  • Daren C. Gooddy
    • 1
  • Helen P. Jarvie
    • 2
  1. 1.British Geological SurveyWallingfordUK
  2. 2.Centre for Ecology and HydrologyWallingfordUK