Transcript Groundwater chemical status in Denmark

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Groundwater chemical status in Denmark
Klaus Hinsby,
GEUS
Climate change and adaptive water management in EU and beyond: Themeday at ATV
winter meeting 9.3.2009 – including relaunch of Danish IAH national chapter.
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WFD & GWD stipulate that:
• EU MS have to achieve good
groundwater status in 2015 based on
environmental standards and good status
objectives for:
• 1) Legitimate uses (drinking water, etc.)
• 2) Associated aquatic ecosystems
• 3) Dependent terrestrial ecosystems
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Good chemical status:
•
A body or a group of bodies of
groundwater shall be considered to be
of good chemical status when:…..
….. relevant threshold values
established ….are not exceeded
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Example of groundwater chemical status
assessment based on good status objectives
for associated aquatic ecosystems:
Harmful Algal Blooms/ HABs
(Cyanobacteria)
Baltic Sea between Denmark and Germany –
25.8.2006
Sea Floor Anoxia
(Horsens Fjord Estuary,
Denmark)
Foto: Klaus Hinsby, GEUS
Photo: NERI – Univ. Aarhus / Peter
Bondo Christensen
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GW TV for nitrate based on good status
objectives for associated aquatic ecosystems:
Photo of
Seafloor
Anoxia
Odense PRB
Photo of
Cyanobacteria
Courtesy GRAS A/S
University of Copenhagen / DHI Water and Environment
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Global review of hypoxia in coastal
marine waters
Diaz and Rosenberg, 2008. Science, 321, 926-929
N fertilizer application and groundwater concentrations
as a function of time 1950 - 2000
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Natural
background
level in gw
From Hinsby et al. Groundwater quality and age. In P. Quevauviller (ed.)
Groundwater Science and Policy. RSC Publishing, London, 2008.
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Threshold value for nitrate in oxic
groundwater in the Odense Pilot River Basin
Nielsen
et al.
2003 =>
Conceptuel model of
Odense Pilot River
Basin:
After Dahl et al., J. Hydrol, 2007
& Hinsby et al. Sci Tot Env, 2008
~1/3 x N to oxic
groundwater
~1/3 x N to
Odense river
<=
~1/3 x N to
Odense Fjord
estuary to
achieve good
status
<=
Derivation of groundwater TV for N based
on sustainable load to Odense river and
Fjord:
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Substance
Ref_discharge
to river
(mg/L)
DF1)
AF 2)
Derived Groundwater
threshold value for
total N (mg/L)
N (aver.)
2.3
1
0.53)
4.6
1
0.08
P
(aver.)
0.08
3) Average
of previous
estimates (Windolf et al. 1
2003, Hansen, 2006 and Hinsby et al. 2008
N (OZD)
P (OZD)
N (RZD)
P (RZD)
(~ 18 mg/l NO3-,
assuming 90 % of
N is in nitrate
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Nitrate in the unsaturated zone and
groundwater at different depths –
data from the LOOP and GRUMO monitoring programmes
DWS = 50 mg/l
TV = 18 mg/l for
oxic groundwater
Average nitrate concentrations in different depths. Data from
LOOP (Grant, 2007) and GRUMO (Thorling, 2007) monitoring
databases and reports.
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Average nitrate concentrations in oxic
groundwater and streams in Danmark,
1990 - 2004
Oxic groundwater
Streams
TV = 18 mg/l
for oxic
groundwater
Data from (Thorling, 2007) and (Kronvang et al., 2008).
Modified from Hinsby and Jørgensen, in press.
Red color indicate
nitrate above DWS =
50 mg/l
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Nitrate
concentrations
in the Åkær
stream
catchment,
december 2008
Red color indicate
nitrate above TV = 18
mg/l
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Nitrate
concentrations
in the Åkær
stream
catchment,
december 2008
Highest value:
101 mg/l in
drainage tile
Lowest value: 0
mg/l in forest
spring
Åkær stream: 30
mg/l
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Cumulative frequency
plot of nitrate in
Danish GRUMO wells
2006-2007 (n = 426)
~40 % > DWS of 50 mg/l
~70 % > TV of 18 mg/l
i.e. ~70 % of oxic
groundwater in
Denmark has a poor
quality when based on
groundwater TVs for
nitrate derived from
good status objectives
for aquatic ecosystems
NO3 (mg/l)
Climate change, Eutrophication and
sea floor anoxia/hypoxia
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Climate models predict
increasing winter
precipitation, hence
increasing river discharge
and nutrient export (~ 8% in
the A2 scenario according to
Andersen et al., Sci. Tot Environ,
365, 2006)
Relative change in river discharge at station 55.01
(Zealand) for the A2 and B2 emission scenarios
compared to present. Modified from van Roosmalen
et al., Vadose Zone Journal, 2007.
As well as increasing Baltic
Sea temperatures
Simulated T in the Baltic Sea in the
A2 and B1 scenarios, Shaffer et al.
Nature Geoscience, 2009
and oxygen depletion
(=> increased risk of algal
blooms and Sea floor
anoxia)
Foto: Klaus Hinsby
Simulated dissolved O2 in the Baltic Sea
in the A2 and B1 scenarios, Shaffer et al.
Nature Geoscience, 2009
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Conclusions and perspectives:
• The major part of the shallow oxic Danish groundwater has
a poor quality according to status assessments based on
EU directives and guidelines
• A major part of shallow oxic Danish groundwater will most
probably not comply with good status objectives in 2015
• Climate change will most probably work against the effect
of measures to reduce nutrient loads
• There’s a strong need for developing new agricultural
practices safe guarding water resources, human and
environmental health
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HAB (cyanobacteria) in the Baltic Sea between Denmark and Germany –
25.8.2006
Thank
You
☺
Foto: Klaus Hinsby