More phosphorus in groundwater than previously thought

Posted on September 26, 2009

Because phosphorus (P) is the main limiting nutrient in most freshwater ecosystems, it’s essential to restrict  artificial inputs of this element to help prevent environmental problems such as plankton blooms and negative impacts on food webs.  Traditionally, phosphorus control has been viewed as a surface-water issue: P has a strong tendency to adsorb onto mineral particles and to form metal complexes in the soil and subsoil, and transfers of phosphorus to and from  groundwater have not been considered important.  This view has now been challenged following the analysis of historical water quality data from 3600 sites in theU.K.and theIrishRepublic, which showed that concentrations of P in groundwater often exceeded national thresholds for nutrient enrichment.  Levels of P at urban sites were significantly higher than elsewhere, and were lowest in areas of woodland and semi-natural grassland or scrub.  More research is needed to better understand two-way transfers of P between groundwater and the surface, and the effects of such transfers on nutrient concentrations. 

Reference:  Holman, I. P., Whelan M. J,. Howden N. J. K,. Bellamy P. H,. Willby N. J,. Rivas-Casado M & McConvey P.  2008.  Phosphorus in groundwater—an overlooked contributor to eutrophication?  Hydrological. Proceses 22, 5121–5127.