We simulate and analyze long-term dynamics of coastal
nitrogen (N) loading and the inland source changes and
processes that may have determined its development over
the past 60-year period and may govern its possible
future responses to variousNsource management scenarios.
With regard to processes, the results show that average
basin-scale N delivery fractions to the coast may not be
representative of the coastal impacts of either diffuse or
point inland sources. The effects of inland source changes
may be greatly redistributed in space-time and delayed
by slow N transport and mass transfer processes in the
subsurface water system of coastal catchments. Extrapolation
of current N transport-attenuation conditions
for quantification of future abatement effects may therefore
be misleading if the extrapolation models do not realistically
represent delayed long-term influences of slow subsurface
processes. With regard to policy, the results show that and
why national Swedish and international Baltic Sea
region policies for coastal N load abatement may be
difficult or impossible to achieve by inland source abatement
only. Large mitigation of both point and diffuse sources
may be necessary to achieve targeted coastal N load
reductions fast and maintain them also in the long term.
2007. Vol. 41, no 7, 2159-2164 p.
Groundwater/surface water interaction, Nutrients and nutrient cycling, Modeling, Water quality, Catchment
One-sentence synopsis: We simulate long-term dynamics of nitrogen (N) loading from land to sea and show that the effects of inland source abatement on coastal N loading may be greatly delayed by slow subsurface N transport and mass transfer processes.