Abstract
Diffuse phosphorus (P) export from agricultural land to surface waters is a significant environmental problem. It is critical to determine the natural background P losses from diffuse sources, but their identification and quantification is difficult. In this study, three headwater catchments with differing land use (arable, pasture and forest) were monitored for 3 years to quantify exports of dissolved (<0.45 µm) reactive P and total dissolved P. Mean total P exports from the arable catchment ranged between 0.08 and 0.28 kg ha−1 year−1. Compared with the reference condition (forest), arable land and pasture exported up to 11-fold more dissolved P. The contribution of dissolved (<0.45 µm) unreactive P was low to negligible in every catchment. Agricultural practices can exert large pressures on surface waters that are controlled by hydrological factors. Adapting policy to cope with these factors is needed for lowering these pressures in the future.
Highlights
Phosphorus (P) is the main element responsible for eutrophication of surface waters in Europe, and enrichment of aquatic ecosystems by P originating from anthropogenic sources has become a huge environmental issue (e.g. Csatho et al 2007; Kronvang et al 2007)
The main losses of P from the anthropogenic environment to surface waters originate from agricultural land (e.g. Sharpley et al 2000; Cordell et al 2009)
This study examined the dynamics of dissolved (\0.45 lm) P in three headwater catchments with a similar climate but under different land uses in three consecutive years
Summary
Phosphorus (P) is the main element responsible for eutrophication of surface waters in Europe, and enrichment of aquatic ecosystems by P originating from anthropogenic sources has become a huge environmental issue (e.g. Csatho et al 2007; Kronvang et al 2007). In the past 20 years, Europe has discharged 0.2–0.3 Tg P year-1 to its coastal waters (Grizzetti et al 2012). These high exports of P can be ascribed to excessive use of fertiliser and manure, resulting in a P imbalance in agricultural soils in developed countries (Vitousek et al 2009). The main losses of P from the anthropogenic environment to surface waters originate from agricultural land Losses of P due to human activities other than agriculture can be very significant (Smil 2000) and there are major challenges associated with reducing the legacy P built up in previous decades (Sharpley et al 2013)
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