Documenting success stories of management of phosphorus emissions at catchment scale: an example from the pilot river Odense, Denmark

Abstract

Documentation of the effects of different mitigation measures adopted at different scales to reduce phosphorus (P) loadings to surface waters is needed to help catchment managers select the best management practices. Water quality monitoring data from the outlets of two paired catchments (the river Odense catchment versus a neighbouring control catchment) on the island of Funen, Denmark, showed significantly different trends in annual flow-weighted P concentrations during the period 2000-2013. A significant downward trend in flow-weighted particulate P (PP) concentrations (0.051 mg P L) and loss (0.155 kg P ha) was detected for the river Odense catchment, whereas a similar trend did not emerge in the control catchment. The observed differences in PP reductions may be due to wetlands acting as P sinks since wetland restoration activities have been much more comprehensive in the river Odense catchment (1.8 ha wetlands km) than in the control catchment (0.5 ha wetland km). The excess downward trend in total P and PP in the river Odense catchment (5,600 kg P and 3,700 kg P) is corroborated by extrapolating the results from a mass-balance study and 10 years of in situ measurements of P storage (3,700 kg P and 15,000 kg P).

Land‐use dominates climate controls on nitrogen and phosphorus export from managed and natural Nordic headwater catchments

“…Patterns of long‐term change in totP concentrations and export were more varied temporally and spatially than for nitrogen; Denmark and Finland had significant declines while Sweden and Norway had significant increases in DRP, resulting in an overall neutral trend for all agricultural catchments (Kronvang, Tornbjerg, Hoffmann, Poulsen, & Windolf, 2016). To what extent climate can explain the patterns of long‐term change in P export is unclear.…”

Integrated assessment of agricultural nutrient pressures and legacies in karst landscapes

“…Demonstration and documentation (e.g. Kronvang et al, 2016) of conservation measure implementation and successes that have improved water quality is encouraged and this impact is most likely to be picked up on well drained sites (highly permeable soil and underlying limestone or similarly permeable geology), as a correlation between farm management and water quality can be quickly interpreted. This is due to soil hydrogeologic characteristics that are conducive to intensive agriculture and also short hydrologic time lags for nutrient transfer (Huebsch et al, 2013).…”