Swedish National Nitrogen Budget – Hydrosphere

Excessive amounts of reactive nitrogen (Nr) in the hydrosphere can impair water quality and alter the functioning of aquatic ecosystems. Monitoring of water bodies and awareness of the existing flows of nitrogen from different sectors in society can support policy making. In this report we quantified the major flows of Nr in the Hydrosphere pool of the Swedish National Nitrogen Budget, according to the methodology provided by the Task Force on Reactive Nitrogen. Calculations were done for one full year using data mainly from 2014 but also from 2015.

In 2014/2015, the largest inflows of Nr to the Swedish hydrosphere were leaching from agriculture (53 kilotonnes, kt), from forests (48 kt), atmospheric deposition (33 kt), leaching from wetlands and other land (20 kt) and municipal wastewater treatment plants (17 kt). In addition, there were minor contributions from industrial wastewaters, small dwellings and from stormwater runoff. The major outflows were transport from the coastal waters to the open sea and marine denitrification (together 127 kt) and denitrification from freshwaters (34 kt) N. In addition, there were quantitatively less important Nr losses through fishing, N2O emissions and water abstraction.

Data come from Svenska MiljöEmissionsData, Statistics Sweden, Nationellt vattentäktsarkiv and SMHI.