1. Nitrate trends in Danish groundwater
Lærke Thorling, Senior Advisor, geochemist
Birgitte Hansen, Senior Scientist, geologist
GEUS; DK
WCG March 21th 2012

2. Groundwater nitrate trends analyses ES&T paper: 45, 228-234: Hansen et al. 2011
Assessment of the general national nitrate trend in groundwater
Aggregation of individual nitrate trends from groundwater monitoring wells

3. 3 types of data
20-year-timeseries from the Danish national groundwater monitoring programme:
app nitrate analyses from app monitoring points
Yearly N surpluses in agriculture from Denmarks Statistics
CFC dating of groundwater once in the period

4. The groundwater monitoring points

5. The national general nitrate trend - 194 oxic groundwater monitoring points
ES&T, 45, :
Hansen et al. 2011

6. 3 age groups of nitrate trends
- 152 oxic monitoring points
Upward
nitrate
trend
Down-ward
nitrate
trend

7. 3 age groups of nitrate trends
152 oxic monitoring points
94 with significant trends

8. Nitrattrends in oxic groundwater

9. Nitrate in young groundwater state 2009-11

10. Conclusions and themes for further work
Trends showing increasing nitrate may be due to « sins » of the past; we have startet to cure
Should we recommand dating and modelling
More guidence on interpretqtion of trends nessesary

11. Regulating agriculture makes a difference to groundwater quality
Photo: Bente Fyrstenberg Nedergaard