Contents - Preface - Summary
Chapter 0, PLAP - Monitoring results May 1999 - June 2002
The Danish Pesticide Leaching Assessment Programme (PLAP) Varslingssystem for udvaskning af pesticider til grundvand (VAP)
Monitoring results May 1999 - June 2002 Third report
Jeanne Kjær, Marlene Ullum, Preben Olsen, Pia Sjelborg, Arne Helweg, Betty Bügel Mogensen, Finn Plauborg, Ruth Grant, Inge S. Fomsgaard and Walter Brüsch.
Geological Survey of Denmark and Greenland Ministry of the Environment
Danish Institute of Agricultural Sciences Ministry of Food, Agriculture and Fisheries
National Environmental Research Institute Ministry of the Environment
Editor : Jeanne Kjær
Cover: Peter Moors
Layout and graphic production: Authors and Lasse Gudmundsson
Printed: June 2003
Price: DKK 200
Geological Survey of Denmark and Greenland Øster Voldgade 10, DK-1350 Copenhagen, Denmark
Phone: +45 3814 2000. Fax: +45 3814 2050 E-mail:
The report is also available at www.pesticidvarsling.dk
© Danmarks og Grønlands Geologiske Undersøgelse, 2003
Table of contents
1.2 STRUCTURE OF THE PLAP
2 PESTICIDE LEACHING AT TYLSTRUP
2.1 MATERIALS AND METHODS
2.1.1 Site description and monitoring design
2.1.2 Agricultural management
2.1.3 Model set-up and calibration
2.2 RESULTS AND DISCUSSION
2.2.1 Soil water dynamics and water balances
2.2.2 Bromide leaching
2.2.3 Pesticide leaching
3 PESTICIDE LEACHING AT JYNDEVAD
3.1 MATERIALS AND METHODS
3.1.1 Site description and monitoring design
3.1.2 Agricultural management
3.1.3 Model set-up and calibration
3.2 RESULTS AND DISCUSSION
3.2.1 Soil water dynamics and water balances
3.2.2 Bromide leaching
3.2.3 Pesticide leaching
4 PESTICIDE LEACHING AT SILSTRUP
4.1 MATERIALS AND METHODS
4.1.1 Site description and monitoring design
4.1.2 Agricultural management
4.1.3 Model set-up and calibration
4.2 RESULTS AND DISCUSSION
4.2.1 Soil water dynamics and water balances
4.2.2 Bromide leaching
4.2.3 Pesticide leaching
5 PESTICIDE LEACHING AT ESTRUP
5.1 MATERIAL AND METHODS
5.1.1 Site description and monitoring design
5.1.2 Agricultural management
5.1.3 Model set-up and calibration
5.2 RESULTS AND DISCUSSION
5.2.1 Soil water dynamics and water balances
5.2.2 Bromide leaching
5.2.3 Pesticide leaching
6 PESTICIDE LEACHING AT FAARDRUP
6.1 MATERIALS AND METHODS
6.1.1 Site description and monitoring design
6.1.2 Agricultural management
6.1.3 Model set-up and calibration
6.2 RESULT AND DISCUSSION
6.2.1 Soil water dynamics and water balances
6.2.2 Bromide leaching
6.2.3 Pesticide leaching
7 PESTICIDE LEACHING AT SLAEGGERUP
7.1 MATERIALS AND METHODS
7.1.1 Site description and monitoring design
7.1.2 Agricultural management
7.1.3 Model set-up and calibration
7.2 RESULTS AND DISCUSSION
7.2.1 Soil water dynamics and water balances
7.2.2 Pesticide leaching
8 DEGRADATION AND SORPTION PARAMETERS
8.1 MATERIALS AND METHODS
8.1.1 Soil sampling
8.1.2 Microbial biomass and activity
8.1.3 Incubation of soil
8.1.5 Degradation kinetics
8.1.6 Determination of sorption
8.2 RESULTS AND DISCUSSION
8.2.1 Soil characteristics
8.2.4 Degradation kinetics
9 PESTICIDE ANALYSIS QUALITY ASSURANCE
9.1 MATERIALS AND METHODS
9.1.1 Internal QA
9.1.2 External QA
9.2 RESULTS AND DISCUSSION
9.2.1 Internal QA
9.2.2 External QA
10 SUMMARY OF MONITORING RESULTS
(pdf-file - 350k)
In 1998, the Danish Government initiated the Danish Pesticide Leaching Assessment Programme (PLAP), an intensive monitoring programme aimed at evaluating the leaching risk of pesticides under field conditions. The first phase of the programme from 1998 to 2001 was funded by the Danish Government, while a two-year prolongation from 2002 to 2003 was funded by the Ministry of the Environment and the Ministry of Food, Agriculture and Fisheries.
The work was conducted by the Geological Survey of Denmark and Greenland (GEUS), the Danish Institute of Agricultural Sciences (DIAS) and the National Environmental Research Institute (NERI) under the direction of a management group comprising Jeanne Kjær (GEUS), Marlene Ullum (GEUS), Svend Elsnab Olesen (DIAS), Arne Helweg (DIAS), Ruth Grant (NERI), Betty Bügel Mogensen (NERI), Christian Ammitsøe (Danish Environmental Protection Agency) and Christian Deibjerg Hansen (Danish Environmental Protection Agency).
This report presents the results for the period May 1999-June 2002. Preliminary results covering part of the period (May 1999-June 2001) have been reported previously (Kjær et al. , 2002). The present report should therefore be seen as a continuation of that report, with the main focus on the monitoring period July 2001-June 2002.
The report was prepared jointly by Jeanne Kjær (GEUS), Marlene Ullum (GEUS), Preben Olsen (DIAS), Pia Sjelborg (DIAS), Arne Helweg (DIAS), Betty Bügel Mogensen (NERI), Finn Plauborg (DIAS), Ruth Grant (NERI), Inge S. Fomsgaard (DIAS) and Walter Brüsch (GEUS). While all authors contributed to the whole report, the aspects for which each author was mainly responsible are as follows:
- Pesticide and bromide leaching: Jeanne Kjær, Preben Olsen and Walter Brüsch
- Soil water dynamics and water balances: Marlene Ullum, Finn Plauborg and Ruth Grant
- Degradation and sorption parameters: Pia Sjelborg, Inge S. Fomsgaard and Arne Helweg
- Pesticide analysis quality assurance: Betty Bügel Mogensen.
Jeanne Kjær June 2003
In 1998, the Danish Government initiated the Pesticide Leaching Assessment Programme (PLAP), an intensive monitoring programme aimed at evaluating the leaching risk of pesticides under field conditions. The objective of the PLAP is to improve the scientific foundation for decision making in the Danish registration procedures for pesticides. The specific aim is to analyse whether pesticides applied in accordance with current regulations leach to the groundwater at levels exceeding the maximum allowable concentration of 0.1 µg/l.
The PLAP includes evaluation of the leaching risk of 27 pesticides at six agricultural sites (ranging from 1.1 to 2.4 ha) representing a wide range of Danish soil and climate conditions. The pesticides were all applied at the maximum permitted rate. Bromide tracer was applied early in the monitoring period and bromide and pesticide concentrations are measured monthly in both the unsaturated and the saturated zones, and weekly in the drainage water. This report presents the monitoring results for the six agricultural sites during the monitoring period May 1999-June 2002. The report is preliminary as the monitoring period is too short to fully evaluate the leaching risk of all applied pesticides. A more complete evaluation integrating the monitoring data with both sorption and degradation studies and modelling of pesticide transport will be made once a more comprehensive data set covering the entire leaching period of more pesticides becomes available. The results hitherto obtained preliminary findings are that:
The monitoring data were supported by hydrological modelling (MACRO version 4.2) providing an overall water balance for each of the six sites. The model was parameterized using measured data or literature/default values, but has not yet been calibrated except for the sandy sites Tylstrup and Jyndevad. The uncalibrated models performed surprisingly well when comparing simulated and observed time series for groundwater table, soil water content and drainage flow.
- Nearly half of the applied pesticides (11 of 27) did not leach during the current monitoring period.
- The monitoring data indicate unacceptable leaching of two of the applied pesticides or their degradation products. Thus glyphosate and its degradation product AMPA and two degradation products of metribuzin leached from the root zone (1 m b.g.s.) in average concentrations exceeding the maximum allowable concentration of 0.1 µg/l.
- At the two sandy sites, previous application of pesticides has caused marked ground water contamination with degradation products of metribuzin. These appear to be relatively stable, and both leached throughout the entire monitoring period, thus indicating continuation of leaching as long as three years after application. There was evidence that the degradation products may persist in the groundwater several years after application.
- Finally, the monitoring data indicate leaching of a further 14 pesticides. The levels of leaching hitherto detected were not unacceptable, however. Although the concentration in several samples exceeded 0.1 µg/l, the average concentration did not.
Sorption and degradation parameters were determined on various combinations of pesticides and soil types representative of the PLAP. The results suggest that:
The quality of the pesticide analyses was evaluated continuously using an intensive quality assurance (QA) system. This consisted of internal control samples prepared by the analysis laboratory as part of their standard method of analysis and both blank and spiked samples prepared in the field and analysed in the laboratory together with the routine samples. The overall quality of the pesticide analysis was considered satisfactory:
- Microbial activity, sorption and degradation rates are low, as is generally the case in subsoil.
- Both degradation rates and sorption differed markedly between soils, thus stressing the importance of having site-specific parameters when modelling the leaching of pesticides.
- The degradation rates were in some cases better described by a two-compartment 1 st + 1 st order model than by the usual 1 st order model. Degradation often encompasses an initial fast degradation rate with a short half-life followed by slower degradation rates with longer half-lives. An error is thus introduced if the simple 1 st order half-life is used in the evaluation of pesticide persistence. Further analysis of the significance of the introduced error for risk assessment of pesticide leaching is thus required.
- Reproducibility of the pesticide analyses was good, with standard deviation generally being in the range 0.003-0.025 µg/l.
- Reproducibility of the degradation products was slightly poorer than that of the mother compounds, standard deviation being 0.004-0.029µg/l.
- Recovery was generally good (> 70%) in the case of spiked samples. Exceptions are fenpropimorph, desmedipham, glyphosate, phenmedipham and pirimicarb at single sites.
- Variation in recovery of the same compound in spiked samples from all field sites indi cate uncertainties in analysis caused by differences in matrix composition.
- Contamination of samples rarely occurred during collection, storage and analysis.