Phosphorus in groundwater—an overlooked contributor to eutrophication?

Abstract

This paper presents the first international assessment of phosphorus concentrations in groundwater, using data from the Republic of Ireland, Northern Ireland, Scotland, England and Wales. Phosphorus is considered to be the main limiting nutrient in most freshwater ecosystems. Controlling phosphorus inputs is thus considered the key to reducing eutrophication and managing ecological quality. Very little attention has been paid to evaluating transfers via groundwater due to the long-held belief that adsorption and metal complex formation retain the majority of potentially mobile phosphorus. In each country, ecologically-important phosphorus thresholds are exceeded in a significant number of groundwater samples. The relative contributions of potential sources for these elevated concentrations are currently unclear but there is evidence to suggest that they are at least partly anthropogenic. The results suggest that groundwater P concentrations are such that they may be a more important contributor to surface water phosphorus than previously thought. Copyright ¸ 2008 John Wiley & Sons, Ltd

Modelling spatially explicit impacts from phosphorus emissions in agriculture

“…The relatively high contributions of groundwater leaching seem to contradict the long-held view that dissolved P is quickly immobilized by adsorption and metal complex formation. However, Holman et al (2008) also suggest that groundwater leaching might be an overlooked contributor to eutrophication.…”

Eutrophication of moderately deep Dutch lakes during the past century: flaws in the expectations of water management?

“…The quality of the River Meuse water deteriorated to reach maximum nutrient concentrations in the 1970s and its nutrient level is still higher than the natural background concentrations (van Vliet & Zwolsman, 2008). This high nutrient loading of the river may also influence the nutrient concentrations in the regional groundwater and contributes to the high TP concentrations observed in floodplain lakes (Shaw et al, 1990;Holman et al, 2008). As a result, the DI-TP concentrations in the dike-breach lakes were between *70 and 300 lg l -1 during the past 50 years.…”

Macronutrient status of UK groundwater: Nitrogen, phosphorus and organic carbon

“…The main sources of anthropogenic P are considered to be NPK fertilisers and animal and human wastes (Holman et al, 2008b). Holman et al (2008a) set out the main sources in more detail as:…”

“…Carbon cycling has been affected by agricultural practices (Bellamy et al, 2005) and, in semi-natural systems (Magnani et al, 2007), through changes in net primary productivity and carbon storage brought about by N deposition (Townsend et al, 1996;Waldrop et al, 2004). The groundwater pool is an important, albeit slowly changing, component of the cycles of N, P and C, and in turn impacts on receptors such as surface water (Holman et al, 2010;Holman et al, 2008b) and dependent wetlands (Krause et al, 2007).…”