Ida H. Olesen and Tove Svendsen

Henriette Kerrn-Jespersen and

Strategies and methods to investigate groundwater pollution with pesticides on a local and regional scale

Henriette Kerrn-Jespersen and

Katerina Hantzi

Katrine Smith

Nina Tuxen

Outline

• Pesticides in groundwater –a problem?

• Sources to groundwater contamination

• Groundwater protection• Groundwater protection

• Distinguishing between point sources and diffuse sources

• Handling point sources

• Conclusions

Pesticides in groundwater – a problem?

• Many countries rely heavily on groundwater for drinking water purposes

• Huge areas in Europe used for agricultural practice

• Many countries aim at avoid advanced water treatment advanced water treatment

• EU Drinking Water Directive:

– 0,1 µg/l for single pesticides and 0,5 µg/l for the total pesticides

– Drinking water standards should apply to groundwater

– In DK: metabolites are treated as pesticides

• EEA assessment: lack of reliable data, but there is a danger

Red: Danger of pesticide pollution in GW

Green: No danger of pesticide pollution in GW

Other: No statements/EEA assessment May 2004/

Pesticides in Danish groundwater

• Detected in 35 % of monitoring

wells and 25 % of drinking water

wells

• Above quality standard (0,1 µg/l)

in 10 % of wells

• Most detections are of now

banned pesticidesbanned pesticides

• Pesticides are the most common

chemical reason closing drinking

water wells

/Geological Survey of Denmark and Greenland, 2011/

Diffuse and point sources

Regulation

Control with illegal

import

Treatment at water

works

Move/optimize

abstraction

Sources and solutions/actions

NEW OLD

DIFFUSE

import Move/optimize

abstraction

Better practice

Identify

Investigate

Remediate

POINT

Groundwater protection

• Many countries focus on regulation on pesticide use• Most findings are with now banned pesticides• Also focus on the old sources• In Denmark many different authorities involved dependent on source

and action– E.g. Danish Regions responsible for handling of old point sources

Need for methods to distinguish

between pesticide problems arising

from point and diffuse sources

How to distinguish between point and diffuse sources from groundwater monitoring data

Project performed by:– Danish EPA (Katrine Smith, Steen Marcher)– Region of Southern Denmark (Ida H. Olesen, Tove Svendsen)– DTU Environment (Philip Binning, Poul L. Bjerg, Angelina Aisopou, Julie Chambon)– Geological Survey of Denmark and Greenland (Lærke Thorling, Walter Brüsch, Kim Esbensen)– Orbicon (Sandra Roost, Julie Kofoed, Nina Tuxen)

Set of indicators

Examples

PointDiffuse

Point

Diffuse

Identification, investigation and remediation of point sources

• Large number of potential point sources

• Only few constitute a real risk to groundwater

• Systematic and cost effective approach needed

Example

Catchment area

Technology Comments

Pump and

treat

• Activated carbon

• Chemical oxidation

• Biological treatment

Excavation • The relevant pesticides do not sorb

to soil

Remediation – possibilities and challenges

to soil

• Sometimes difficult to locate

hotspot

In situ

technologies

• Natural or enhanced degradation

• Chemical oxidation

• Zero valent iron

• Potentially formation of persistent

metabolites

Conclusions

• The use of pesticides can constitute a threat to groundwater and drinking water

• Different source types require different actions

• Several authorities are involved

• A list of ”indicators” can be used to distinguish between sources

• Point sources can be identified and investigated using a systematic approach

• Remediation of pesticide point sources is probably possible but field experiences are few