Hvordan fastsættes tærskel- og reference værdier i grundvand –

udvalgte EU og DK eksempler

Klaus Hinsby, GEUS

ATV temamøde nr. 29, Radisson SAS Hotel, Odense, 23.4.2008

• For at beskytte sundhed og miljø skal EU medlemslande arbejde mod at opnå god kemisk og kvantitativ tilstand for grundvand i 2015.

• Den kemiske tilstandsevaluering foretages v.hj.a tærskelværdier som fastsættes for de stoffer der truer grundvandsforekomsten i flg. VRD art.5 karakteriseringen (dog minimumliste),

• Tærskelværdier er kvalitetskrav, der skal overholdes for at sikre god kemisk tilstand og beskytte såvel afhængige økosystemer som ”legitime anvendelser”

Baggrund:

”BRIDGE” projektet:

• EU projektet ”BRIDGE” (2004-2006) fik til opgave at udvikle og teste en metode til fastlæggelse af tærskelværdier (”TV”) på et videnskabeligt grundlag

• Den udviklede metode blev delvist testet i 14 lande i en række forskellige typer af grundvandsmagasiner og ”økoregioner” defineret i Vandrammedirektivet.

Sand and gravel (11)

Sandstone (3)

Karstic carbonates (2)

Palaeozoic carbonates (1)

Crystalline rocks (1)

Volcanic rocks (1)

LIsbon, 17-21 September 2007IAH 2007 – Groundwater and Ecosystems

Typer af grundvands-magasiner undersøgt i BRIDGE

Wendland et al., Env. Geology, 2007

WFD Ecoregions for rivers and lakes with BRIDGE case studies

Transitional or coastal water ecosystems that receive direct or indirect discharge from groundwater bodies investigated in BRIDGE

LIsbon, 17-21 September 2007IAH 2007 – Groundwater and Ecosystems

BRIDGE methodology for groundwater TV derivation:

Hinsby et al., Sci Tot Environ, in press

• Beregning af TV’er ud fra baggrundsværdier og miljøstandarder (f.eks drikkevandskrav) - for grundvand ”selv”.

XLIsbon, 17-21 September 2007IAH 2007 – Groundwater and Ecosystems

BRIDGE metode for fastlæggelse af baggrundsværdier:

LIsbon, 17-21 September 2007IAH 2007 – Groundwater and Ecosystems

High level of knowledge/data

(e.g. env. Tracers etc. –

fx Hinsby og Rasmussen, 2008)

Medium level of knowledge/data

(BRIDGE: NO3 < 10 mg/L, etc.)

Low level of knowledge/data

(check NBL of similar aquifer type)

Baggrundsværdier varierer betydeligt:

Modified from Shand & Edmunds, (in: Edmunds, WM and Shand, P., Natural Groundwater Quality, Wiley-Blackwell, London, 2008.)

25 4000 0.45 30

The BRIDGE methodology propose to select the NBL as the 90th percentile.

LIsbon, 17-21 September 2007IAH 2007 – Groundwater and Ecosystems

TV1

TV2 TV2

NBL

NBL

NBL

TVs derived for groundwater “itself” (p90):

LIsbon, 17-21 September 2007IAH 2007 – Groundwater and Ecosystems

WG C meeting Ljubljana 22.4.2008

Tærskelværdier baseret på miljømål og reference-værdier for overfladevand

Odense river

Lake Arreskov

Odense fjord / estuary

Photo Courtesy: Fyns Amt (County of Fyn)

Data from NASA (Aqua Modis) - Courtesy GRAS A/S

University of Copenhagen / DHI Water and Environment

Eutrophication:

Harmful algal blooms (Cyanobacteria) in North European coastal waters,

August 8, 2006

Photo

next

slide

OPRB

Hinsby et al., Sci Tot Environ, in press

HARMFUL ALGAL BLOOM (Cyanobacteria)

BALTIC SEA BETWEEN DENMARK AND GERMANY – 25.8.2006

Photo from ferry: Klaus Hinsby

Svovl bakterier på bunden af

Odense fjord

Undersøgelser af Odense Fjord estimerer at N og P belastningen skal reduceres med hhv. en faktor 0.3 og 0.5 for at opnå god status (Nielsen et al., 2003, DMU rapporter).

Konceptuel model af Odense å oplandet:

Odense Fjord

Odense åVi antager at N og P belastningen i Odense å skal reduceres tilsvarende med hhv. en faktor 0.3 og 0.5

Land use: ~70 % Agriculture

Hinsby et al., Sci Tot Environ, in press

N x 0.3

P x 0.5

Current loads and future sustainable loads to Odense Fjord (N and P):

Table 2. Current (1997-2002) total N and total P loads to Odense Fjord (c2), environmental objective of Odense Fjord (c3), N and P loads (c5) and average concentrations (c6) of Odense river (OR), and estimated sustainable loads (c7) and concentrations (c8) of Odense river needed to comply with the WFD environmental objectives.

c1 c2 c3 c4 c5 c6 c7 c8

Substance Total Load 3)

to OF(t/year)

REF_f 4)

Load(t/year)

Rf 5)

(=C3/C2)

ORKratholmload 6)

(t/year)

OR Kratholm(mg/L)

OR REF -discharge (=c4 x c5) (t/year)

OR REF- discarge to OF (=c4 x c6)(mg/L)

1997-02     1998-02 1998-02 Goal2015

Goal2015

TN1) 2434 800 0.3 1200 7.0 400 2.3TP2) 64 30 0.5 27 0.16 14 0.081) TN= org. N + DIN (NO3-N + NO2-N + NH4-N) 2) TP = Ppart. + PO4-P 3) Fyns Amt (2003), 4) Nielsen et al. (2003), 5) Reduction factor, 6) Fyns Amt data.

Annual runoff in Odense river (Kratholm) = 1.7 x 108 m3/year

x 0.3

x 0.5

Larsen et al. 2008

Odense river monitoring data, 1990-2002:

mg/L(mM)

DAF (NO3-N) = Cobs /Cae = 0.4

Average of Danish agricultural monitoring sites 1990-2002.

Depth of monitored drains and wells 1-5 m.

5m

redox front

Average of groundwater monitoring wells in OPRB 1990-2002 for wells with screen top at a depth of 10 – 20 m.

Current loads and future sustainable loads to Odense Fjord (N and P):

Table 2. Current (1997-2002) total N and total P loads to Odense Fjord (c2), environmental objective of Odense Fjord (c3), N and P loads (c5) and average concentrations (c6) of Odense river (OR), and estimated sustainable loads (c7) and concentrations (c8) of Odense river needed to comply with the WFD environmental objectives.

c1 c2 c3 c4 c5 c6 c7 c8

Substance Total Load 3)

to OF(t/year)

REF_f 4)

Load(t/year)

Rf 5)

(=C3/C2)

ORKratholmload 6)

(t/year)

OR Kratholm(mg/L)

OR REF -discharge (=c4 x c5) (t/year)

OR REF- discarge to OF (=c4 x c6)(mg/L)

1997-02     1998-02 1998-02 Goal2015

Goal2015

TN1) 2434 800 0.3 1200 7.0 400 2.3TP2) 64 30 0.5 27 0.16 14 0.081) TN= org. N + DIN (NO3-N + NO2-N + NH4-N) 2) TP = Ppart. + PO4-P 3) Fyns Amt (2003), 4) Nielsen et al. (2003), 5) Reduction factor, 6) Fyns Amt data.

Annual runoff in Odense river (Kratholm) = 1.7 x 108 m3/year

x 0.3

x 0.5

Table 3. Reference (sustainable) average groundwater discharge concentrations to Odense river (incl. drainage) and groundwater threshold values for N and P

Substance REF_concen-tration in Odense river (mg/L)

DAF 1) Derived

groundwater TV(mg/L)

N (average) 2.3 0.52) 4.6 ( ~20 mg/L NO3)

P (average) 0.08 - ? (1) 0.08

1) Dilution Attenuation Factor 2) Average of total dilution and attenuation in groundwater bodies, the riparian Zone, and Odense river estimated in two different studies (Windolf et al, 2003, Hansen et al. 2007)

Østersøen mellem Gedser og Rostock – 25.8.2006

TAK

Foto: Klaus Hinsby