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

Baggrund: 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”

”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.

Wendland et al., Env. Geology, 2007 LIsbon, 17-21 September 2007 Typer af grundvands-magasiner undersøgt i BRIDGE Sand and gravel (11) Sandstone (3) Karstic carbonates (2) Palaeozoic carbonates (1) Crystalline rocks (1) Volcanic rocks (1) Wendland et al., Env. Geology, 2007 IAH 2007 – Groundwater and Ecosystems

WFD Ecoregions for rivers and lakes with BRIDGE case studies LIsbon, 17-21 September 2007 Transitional or coastal water ecosystems that receive direct or indirect discharge from groundwater bodies investigated in BRIDGE WFD Ecoregions for rivers and lakes with BRIDGE case studies IAH 2007 – Groundwater and Ecosystems

BRIDGE methodology for groundwater TV derivation: Hinsby et al., Sci Tot Environ, in press

LIsbon, 17-21 September 2007 Beregning af TV’er ud fra baggrundsværdier og miljøstandarder (f.eks drikkevandskrav) - for grundvand ”selv”. X IAH 2007 – Groundwater and Ecosystems

BRIDGE metode for fastlæggelse af baggrundsværdier: LIsbon, 17-21 September 2007 BRIDGE metode for fastlæggelse af baggrundsværdier: 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) IAH 2007 – Groundwater and Ecosystems

Baggrundsværdier varierer betydeligt: LIsbon, 17-21 September 2007 Baggrundsværdier varierer betydeligt: The BRIDGE methodology propose to select the NBL as the 90th percentile. 25 4000 0.45 30 Modified from Shand & Edmunds, (in: Edmunds, WM and Shand, P., Natural Groundwater Quality, Wiley-Blackwell, London, 2008.) IAH 2007 – Groundwater and Ecosystems

TVs derived for groundwater “itself” (p90): LIsbon, 17-21 September 2007 TVs derived for groundwater “itself” (p90): NBL NBL NBL TV1 TV2 TV2 IAH 2007 – Groundwater and Ecosystems

WG C meeting Ljubljana 22.4.2008

Tærskelværdier baseret på miljømål og reference-værdier for overfladevand Odense river Odense fjord / estuary Lake Arreskov Photo Courtesy: Fyns Amt (County of Fyn)

Harmful algal blooms (Cyanobacteria) in North European coastal waters, 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 Data from NASA (Aqua Modis) - Courtesy GRAS A/S University of Copenhagen / DHI Water and Environment

Photo from ferry: Klaus Hinsby 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: Land use: ~70 % Agriculture N x 0.3 P x 0.5 Odense Fjord Odense å Vi antager at N og P belastningen i Odense å skal reduceres tilsvarende med hhv. en faktor 0.3 og 0.5 Hinsby et al., Sci Tot Environ, in press

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 Rf 5) (=C3/C2) OR Kratholm load 6) (mg/L) OR REF -discharge (=c4 x c5) OR REF- discarge to OF (=c4 x c6) 1997-02   1998-02 Goal 2015 TN1) 2434 800 0.3 1200 7.0 400 2.3 TP2) 64 30 0.5 27 0.16 14 0.08 1) 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: (mM) mg/L

Average of Danish agricultural monitoring sites 1990-2002. Depth of monitored drains and wells 1-5 m. DAF (NO3-N) = Cobs /Cae = 0.4

redox front 5m 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 Rf 5) (=C3/C2) OR Kratholm load 6) (mg/L) OR REF -discharge (=c4 x c5) OR REF- discarge to OF (=c4 x c6) 1997-02   1998-02 Goal 2015 TN1) 2434 800 0.3 1200 7.0 400 2.3 TP2) 64 30 0.5 27 0.16 14 0.08 1) 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 N (average) 2.3 0.52) 4.6 ( ~20 mg/L NO3) P (average) 0.08 - ? (1) 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