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Geological Survey of Denmark and Greenland
Øster Voldgade 10, DK-1350 Copenhagen, Denmark
Phone: +45 38 14 20 00, fax +45 38 20 50
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 setup 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 setup 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 setup 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 setup and calibration
6.2 RESULTS AND DISCUSSION
6.2.1 Soil water dynamics and water balances
6.2.2 Bromide leaching
6.2.3 Pesticide leaching
7 PESTICIDE ANALYSIS QUALITY ASSURANCE
7.1 MATERIALS AND METHODS
7.1.1 Internal QA
7.1.2 External QA
7.2 RESULTS AND DISCUSSION
7.2.1 Internal QA
7.2.2 External QA
7.3 SUMMARY AND CONCLUDING REMARKS
8 SUMMARY OF MONITORING RESULTS
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 analyze whether pesticides applied in accordance with current regulations will result in leaching of the pesticide and/or its degradation products to groundwater in unacceptable concentrations.
Throughout the monitoring period (1999-2013) 101 pesticides and/or degradation products have been analyzed in PLAP comprising five agricultural fields (1.2 to 2.4 ha) grow with different crops. The 15 most frequently analyzed pesticides and/or degradation products includes analyzes of 2.300-4.000 water samples collected from groundwater, drainage, and suction cups, including quality analysis samples (Table 0.1).
Evaluation of pesticides is based upon 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.).
This report presents the results of the monitoring period July 2011-June 2013 comprising 9.090 single analyzes conducted on water samples collected at the five PLAP-fields: two sandy fields (Tylstrup and Jyndevad) and three clayey till fields (Silstrup, Estrup and Faardrup). In this period, PLAP has evaluated the leaching risk of 19 pesticides and 22 degradation products (Table 0.2) after applying the maximum allowed dose of the specific pesticide to the specific crop (Table 0.3).
Results covering the period May 1999-June 2011 have been reported previously (Kjæret al. , 2002, Kjær et al., 2003, Kjær et al., 2004, Kjær et al., 2005c, Kjær et al., 2007, Kjær et al., 2008, Kjær et al., 2009, Rosenbom et al., 2010b, Kjær et al., 2011, and Brüsch et al., 2013a+b). The present report should therefore be seen as a continuation of previous reports with the main focus on the leaching risk of pesticides applied during June 2011- June 2013.
Highlights from the monitoring period June 2011-June 2013:
The results of the entire monitoring period 1999-2013 covering 50 pesticides and 51 degradation products show that:
- Bentazone was applied to peas at Jyndevad and Estrup in 2013, white clower at Faardrup in 2012 and 2013, and maize at Jyndevad in 2012. At the sandy field Jyndevad bentazone was found to leaching through the variably-saturated zone (suction cups) after application on peas in 2013. It was, however, only detected once (0.01 µg/L) in a mixed groundwater sample from the horizontal well at 2.5 m b.g.s. This confirmes the leaching pattern detected after the bentazon application on maize in 2012, where it was frequently detected in the variably-saturated zone (suction cups) in concentrations up to 1.9 µg/L, but not in the groundwater. After use on clower, at the clayey till field Faardrup in 2012 and 2013, bentazone was detected in one drainage sample (0.02 µg/L). Bentazone did not leach after use on peas at the clayey till field Estrup in 2013. In total, bentazone has until 15 May 2013 been applied 17 times to the five fields in PLAP and on different crops. In the period May 2001-June 2013 bentazone has been detected in 66 groundwater samples, where eight groundwater samples had concentration above 0.1 µg/L. A total of 3.728 groundwater samples has been analyzed for bentazone.
- Metalaxyl-M, and especially its two degradation products CGA 108906 and CGA 62826, have been detected in high frequency and concentrations both in the variably-saturated zone and in the groundwater at the two sandy PLAP-fields, why the compounds still will be under evaluation in PLAP. Metalaxyl-M was detected a few times in low concentrations in watersamples from the variably-saturated zone (suction cups). The degradation products CGA 108906 and CGA 62826, however, leached to 1 m depth in concentrations often exceeding 0.1 µg/L up to 3 years after application. The highest concentrations for both compounds were detected 1 m depth in concentrations up to 3.7 µg/L (January 2012). In the period June 2011-June 2013 both degradation products were found in 83-100% of the water samples from the variably-saturated zone (suction cups) and especially CGA 108906 was detected frequently in groundwater samples (75-83%) from Tylstrup and Jyndevad, where 20-30% of the analyzed groundwater samples exceeded 0.1 µg/L. Concentration measured in water samples from the variably-saturated zone and from a horisontal well collecting groundwater just beneath the fluctuating groundwater table at Jyndevad, clearly indicate leaching of the compounds after metalaxyl-M was applied to potatoes in 2010 at the PLAP-fields. As a consequence of these monitoring results, the Danish EPA has withdrawn the approval of metalaxyl-M per August 1st, 2013.
- Fluazifop-P-butyl was used in a new dose (50% lower than in past applications) in the spring 2011 at the clayey till field Silstrup, and leaching of the degradation product TFMP was negligible in 2011. Before the regulation, TFMP leached to both drainage and groundwater in concentrations above 0.1 µg/L at Silstrup. Fluazifop-Pbutyl was also applied at Faardrup in May 2011, and TFMP did not leach. In April 2012 Fluazifop-P-butyl was applied on red fescue at Silstrup (50% reduced dose), and TFMP-concentrations exceeding 0.1 µg/L was measured in drainage and groundwater. In the monitoring year 2013, TFMP was found in both drainage and groundwater, but in concentrations below 0.1 µ/L. Given these different TFMPleaching scenarios, the leaching risk of the compound will still be evaluated in PLAP in the years to come. Fluazifop-P-butyl has been applied 10 times in PLAP at four of the fields.
- After application on red fescue at the clayey till field Silstrup September 2012, glyphosate and AMPA were found in drainage in concentrations up to 0.66 µg/L. The compounds were however not exceeding 0.1 µg/L in groundwater. Here glyphosate was only detected in 10 groundwater samples from vertical wells and in three groundwater samples from a horizontal well. At the clayey till field Estrup, concentrations of glyphosate and AMPA in drainage both exceeded 0.1 µg/L frequently after glyphosate application on winter wheat in October 2011. In the groundwater AMPA was never detected, only glyphosate was occasionally detected in two groundwater samples with concentrations ≥ 0.1 µg/L (0.21 and 0.13 µg/L). At the clayey till field Faardrup, glyphosate was found in low concentrations (0.025 and 0.019 µg/L) in two samples from two levels in a vertical monitoring well after application after harvest of spring barley and white clover in October 2011. Monitoring at Faardrup stopped in August 2012.
- Azoxystrobine was applied at the clayey till field Estrup in June 2012, and both azoxystrobine and CyPM leached to drainage in concentrations above 0.1µg/L. CyPM was detected in seven groundwater samples from both the new and old horizontal wells, and one sample was exceeding 0.1 µg/L. There was no detections in groundwater samples collected from the vertical monitoring wells.
- The fungicide metrafenone was applied twice, 9 May and 7 June 2011, at the clayey till field Estrup. 20 water samples of drainage and one of groundwater contained metrafenone in concentrations <0.1 µg/L.
- Diflufenican was applied in April 2012 and in November 2012 (red fescue and winter wheat) at the clayey till field Silstrup. Diflufenican was detected in 9 water samples of the drainage and in one groundwater sample. One drainage and one groundwater sample exceeded 0.1 µg/L. The degradation product of diflufenican AE-B107137 was detected in 5 water samples of the drainage, while the other degradation product AE-05422291 was not detected (Table 0.2). Diflufenican and the two degradation products were not detected in groundwater nor drainage after application at spring barley in April 2011 at the sandy field Jyndevad.
- Aclonifen, aminopyralid, boscalid, bromoxynil, clomazon, cyazofamid, ioxynil, mesotrione, propyzamid, prosulfocarb, tribenuron-methyl and degradation products were not detected in drainage and groundwater during the monitoring period. The degradation product thiacloprid amid of thiacloprid was detected in one sample from the drainage, while thiacloprid was not detected. Tebuconazole was detected in two water samples collected in the drainage in August and September 2012 (Table 0.2).
In order to describe the water flow through the variably-saturated zone and into the groundwater zone, a bromide tracer has been applied at least twice to each of the five PLAP-fields. Bromide and pesticide concentrations are measured monthly in both the variably-saturated zones and in the saturated zones, and weekly in the drainage.
- Of the 50 pesticides applied, 16 pesticides and/or their degradation product(s) (aclonifen, aminopyralid, boscalid, clopyralid, chlormequat, cyazofamid, desmedipham, fenpropimorph, florasulam, iodosulfuron-methyl-natrium, linuron, mesotrione, thiacloprid, thiamethoxam, tribenuron-methyl and triasulfuron) were not detected in either drainage or groundwater during the entire monitoring period.
- The monitoring data indicate pronounced leaching of 16 of the applied pesticides and/or their degradation product(s). The following compounds leached through the soil entering tile drains or suction cups (placed 1 m depth) in average concentrations exceeding 0.1 µg/L:
- azoxystrobin and its degradation product CyPM
- CL153815 (degradation product of picolinafen)
- AE-B107103 (degradation product of diflufenican)
- pirimicarb-desmethyl-formamido (degradation product of pirimicarb)
- glyphosate and its degradation product AMPA
- CGA 108906 and CGA 62826 (degradation products of metalaxyl-M)
- PPU (degradation products of rimsulfuron)
- bifenox-acid (degradation product of bifenox)
- TFMP (degradation product of fluazifop-P-butyl)
- metamitron and its degradation product desamino-metamitron
- desamino-diketo-metribuzin and diketo-metribuzin (degradation products of metribuzin)
- terbuthylazine and its degradation products desethyl-terbuthylazine, 2-hydroxy-desethyl-terbuthylazine and hydroxy-terbuthylazine.
For pesticides and/or their degradation products marked in italics, pronounced leaching is mainly confined to the depth of 1 m b.g.s., where pesticides were frequently detected in water samples collected from tile drains and suction cups, while a limited number of detections (fewer than five samples per field) exceeding 0.1 µg/L were detected in water samples collected from groundwater monitoring wells.
For the pesticides and/or their degradation products marked in bold, pronounced leaching below the depth of 1 m b.g.s. was observed. Apart from PPU, these were all frequently detected in groundwater in concentrations exceeding 0.1µg/L more than six months after application.
- The monitoring data also indicate leaching of an additional 18 pesticides, but inlow concentrations. Although concentrations exceeded 0.1 µg/L in several water samples collected from suction cups and tile drains (1 m b.g.s.), average leaching concentrations on a yearly basis did not exceed 0.1 µg/L. None of the compounds were detected in water samples from the groundwater monitoring wells in concentrations exceeding 0.1 µg/L.