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| Titel |
Trends of nitrogen and phosphorus input into Lake Neusiedl from wastewater treatment plants and non-point sources |
| VerfasserIn |
Paul Kinner, Gerhard Heiss, Gerhard Soja |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074183
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| Zusammenfassung |
| Lake Neusiedl (Austria) is a mesotrophic to eutrophic shallow steppe lake. Due to its low
water volume and the lack of a natural outflow, excessive nutrient input is a special risk for
this lake. In recent years, improved waste water treatment technologies have reduced the N
and P loads of the inflows although all municipalities surrounding Lake Neusiedl (with one
exception) and the cities and municipalities within the catchment area of the river
Wulka discharge their (treated) wastewater into Lake Neusiedl. The amount of
wastewater in 2010 was more than 22 x 106 m3. Although the amount of wastewater
increased by more than 70 % in the last 30 years, it was possible to reduce the
ammonium load from 38 t/a to 8 t/a (as NH4-N), the nitrate load from 83 t/a to
34 t/a (as NO3-N), the phosphate load from 8 t/a to 3 t/a (as PO4-P) and the total
phosphorus load from 11 t/a to 6 t/a (comparison of the average annual loads of 1982 and
2010).
Another environmental risk for Lake Neusiedl is the nitrogen input due to agricultural
activities. Therefore a pilot action within the EULAKES-project focused on the nitrate levels
during annual cycles (2011-2012) in groundwater as well as in selected rivers, channels and
ditches discharging into Lake Neusiedl.
The monitoring programme demonstrated clearly that the major contribution of the total
nitrogen load discharged by surface water into Lake Neusiedl originated from River
Wulka. For a general assessment of the influence of surface water discharge into Lake
Neusiedl it is necessary to investigate the data of River Wulka for a longer period.
Therefore data at the monitoring station Schützen were analysed for the period
1992-2010.
Evaluation of the monitoring data showed that due to the higher nitrogen concentrations
at higher average annual discharges the inorganic nitrogen load was about 6.5 times higher in
2010 (average discharge of Wulka 2.1 m3/s) than in the year 2001 (average discharge of
Wulka 0.56 m3/s). The total inorganic nitrogen load amounted to 304 tons in 2010, compared
to 47 tons in 2001. In the period 1992-2010 the nitrogen load caused by diffuse sources
was 4.3 times higher than the point source nitrogen load (2 wastewater treatment
plants).
The proportion of total discharge, of inorganic nitrogen load and of phosphorus load
caused by the two wastewater treatment plants depended on the discharge rate of the river
Wulka (monitoring station Schützen). In 2001 (low precipitation year: 578 mm annual sum)
point sources contributed about 47% of the discharge, 51% of the nitrogen load and 65% of
the phosphorus load of the river Wulka. In 2010 (high precipitation year: 945 mm annual
sum) point sources contributed 25% of the discharge, 11% of the nitrogen load and 31% of
the total phosphorus load.
In the period 1992 to 2010 the inorganic nitrogen load caused by surface water
(Wulka, WWTP, creeks and channels) varied from 65 t/a to 675 t/a (mean:233 t/a). |
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