In 1998, the Danish Parliament 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 regulation of pesticides. The specific aim is to analyse whether pesticides applied in accordance with current regulations leach to groundwater in unacceptable concentrations. The programme currently evaluates the leaching risk of 41 pesticides and 40 degradation products at five agricultural sites ranging in size from 1.1 to 2.4 ha. The evaluation is based upon monitoring results representing detections in 1 meters depth (water collected via drains and suction cups) and detections in groundwater monitoring screens (1.5-4.5 meter below ground surface, hereafter m b.g.s.). The results of the period 1999-2009 show that regarding:

Yearly average concentration 1 m b.g.s.

Of the 41 pesticides applied, 12 pesticides and/or their degradation product(-s) (clopyralid, chlormequat, desmedipham, fenpropimorph, florasulam, iodosulfuron-methyl-sodium, linuron, mancozeb, metsulfuron-methyl, phenmedipham, thiamethoxam, tribenuronmethyl, and triasulfuron) did not leach during the 1999-2009 monitoring period.

• 13 of the applied pesticides exhibited pronounced leaching of the pesticide and/or their degradation product(-s) 1 m b.g.s. in yearly average concentrations exceeding 0.1 μg/l (maximum allowable concentration). Thus:

exhibited and/or their degradation product(-s) 1 m b.g.s. in yearly average concentrations exceeding 0.1 μg/l (maximum allowable concentration). Thus:

o azoxystrobin and its degradation product CyPM

o bentazone

o ethofumesate

o TFMP (degradation product of fluazifop-P-butyl)

o glyphosate and its degradation product AMPA

o metamitron and its degradation product metamitron-desamino

o metribuzin-desamino-diketo and metribuzin-diketo (degradation products of metribuzine)

o CL153815 (degradation product of picolinafen)

o pirimicarb-desmethyl-formamido (degradation product of pirimicarb)

o propyzamide

o PPU and PPU-desamino (degradation products of rimsulfuron)

o terbuthylazine and its degradation products: desethyl-terbuthylazine, desiospropyl-atrazine, 2-hydroxy-desethyl-terbuthylazine, and 2-hydroxy-terbuthylazine

o tebuconazole were frequently detected in samples from suction cups and drainage systems.

1. The monitoring data also indicate leaching of an additional 16 pesticides, but in low concentrations. Although concentrations exceeded 0.1 μg/l in several samples, average leaching concentrations on a yearly basis did not.

5 etections in groundwater monitoring screens D

1. Of the 41 pesticides applied, 16 pesticides and/or their degradation products (picolinafen, amidosulfuron, bromoxynil, clomazone, epoxiconazole, mesosulfuron-methyl, triflusulfuron-methyl, clopyralid, chlormequat, florasulam, iodosulfuron-methyl-sodium, linuron, metsulfuron-methyl, thiamethoxam, tribenuronmethyl, and triasulfuron) were not detected during the 1999-2009 monitoring period.

• 9 of the pesticides and/or their degradation products:

o bentazone

o ethofumesate

o TFMP and fluazifop-P (degradation products of fluazifop-P-butyl)

o glyphosate and its degradation product AMPA

o metamitron and its degradation product metamitron-desamino

o metribuzin-desamino-diketo and metribuzin-diketo (degradation pro-ducts of metribuzin)

o propyzamide

o PPU (degradation product of rimsulfuron)

o terbuthylazine and its degradation product desethyl-terbuthylazine. were in some instances detected in the groundwater monitoring wells in concentrations exceeding 0.1 μg/l. Consequently, the Danish Environmental Protection Agency baned the use of metribuzin and inforced considerable restrictions on the use of terbuthylazine, which has now been totally banned. In the autumn 2008, the Danish Environmental Protection Agency enforced considerable restrictions on the application of fluazifop-P-butyl, which, given the pronounced leaching of its degradation product TFMP have proven highly needed. Leaching of TFMP relating to the present-day more restrictive terms is now being evaluated via PLAP. For the rest of the compounds it is assessed by the Danish Environmental Protection Agency that no restriction is needed given a yearly average concentration not exceeding 0.1 μg/l. New results from one of PLAP-field-sites show that late sommer periods with several pronounced rain events (more than 50 mm/day) can generate leaching of the herbicide glyphosate through drained, clayey soils into the groundwater - also this will be evaluated further via PLAP.

in the groundwater monitoring wells . Consequently, the Danish Environmental Protection Agency baned the use of metribuzin and inforced considerable restrictions on the use of terbuthylazine, which has now been totally banned. In the autumn 2008, the Danish Environmental Protection Agency enforced considerable restrictions on the application of fluazifop-P-butyl, which, given the pronounced leaching of its degradation product TFMP have proven highly needed. Leaching of TFMP relating to the present-day more restrictive terms is now being evaluated via PLAP. For the rest of the compounds it is assessed by the Danish Environmental Protection Agency that no restriction is needed given a yearly average concentration not exceeding 0.1 μg/l. New results from one of PLAP-field-sites show that late sommer periods with several pronounced rain events (more than 50 mm/day) can generate leaching of the herbicide glyphosate through drained, clayey soils into the groundwater - also this will be evaluated further via PLAP.

1. Additional 16 pesticides were detected, however, in low concentrations not exceeding 0.1 μg/l.

The PLAP initially evaluated the leaching risk at six agricultural sites representing a range of Danish soil and climate conditions. Monitoring at the Slaeggerup site was terminated on 1 July 2003, and results from that site are not included in the present port. For the monitoring results from this site see Kjær et al. (2004).

re

Pesticides were applied in the maximum permitted dose. In order to describe water transport, a bromide tracer was applied to the fields. Bromide and pesticide concentrations are measured monthly in both the unsaturated and the saturated zones, and weekly in the drainage water. This report covers the period May 1999-June 2009 and presents the monitoring results from the five agricultural sites presently monitored. The main focus is on evaluating the leaching risk of the pesticides applied during 2007.