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Studies of nutrient emissions into surface
waters are usually only performed for years in recent
decades. However, estimating nutrient emissions for the
more distant past enables us to identify the main factors
responsible for the increasing nutrient contamination since
the end of the nineteenth century. We focussed on the Oder
River System for 1875–1944, divided into 10-year periods.
Nutrient emissions into surface waters were calculated with
the model MONERIS (MOdelling Nutrient Emissions in
RIver Systems). For seven different pathways and eight
sources, the total nitrogen (TN) emissions were quantified.
The TN-emissions into the surface waters for 1880
amounted to 25,300 t year-1, and by 1940, this value had
almost doubled to 46,600 t year-1. In 1880, 57% of TNemissions
into the surface waters derived from urban systems,
due to the high amount of untreated waste water. In
1940, only 34% of TN-emissions into surface waters
derived from urban systems, despite a population growth of
about 27% since 1880; point sources via newly constructed
waste water treatment plants (WWTPs) increased from 4%
(1880) to 26% (1940). During the study period, the main
changes in diffuse TN-emissions from agriculture were
caused by inorganic fertilizer application and nitrogen
deposition, while TN-emissions via urban sources were
shifted to point sources due to population growth and the
construction of new WWTPs. Furthermore, estimated TN-concentrations
could make a contribution to construct
benchmarks for nutrient concentrations according to the
physiochemical properties to implement the European
Water Framework Directive (WFD 2000).
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