Geological Survey of Denmark and Greenland Bulletin 35, 2016, 17-22 17© 2016 GEUS. Geological Survey of Denmark and Greenland Bulletin 35, 17–22 . Open access: www.geus.dk/publications/bull The Danish Pesticide Leaching Assessment Programme (PLAP) was initiated in 1998 by the Danish Parliament in order to evaluate whether the use of approved pesticides will result in an unacceptable contamination of the ground- water, if applied under field conditions in accordance with current Danish regulation. In this programme, water sam- ples from variably saturated soil and groundwater collected at five cultivated fields are analysed for selected pesticides and their degradation products. The PLAP results are sum- marised and evaluated in yearly reports and used by the Danish Environmental Protection Agency in the regula- tion of pesticides in Denmark (Brüsch et al. 2015). In order to represent typical farming scenarios in Denmark, the test fields are situated on meltwater and marine sands, and on tile-drained clayey soils in till areas. Methods The five cultivated PLAP fields (1.2–2.4 ha), represent- ing different soils and hydrogeological settings, spread across Denmark (Fig. 1) are located at Silstrup, Estrup and Faardrup with tile-drained clayey soils, and at Tylstrup and Jyndevad with sandy soils (Lindhardt et al. 2001). The groundwater table is shallow at all fields, which enables a rapid detection of any pesticide leaching to the ground- water (Table 1). The PLAP fields are farmed according to conventional agricultural practice, and pesticides are ap- plied in the maximum permissible doses and as specified in the regulations. Water samples are collected weekly from drainage at the clayey till fields, and monthly from standard teflon suction cups in the unsaturated zone at the sandy fields, and from horizontal and vertical groundwater monitoring wells at all fields. The wells are installed in buffer zones surrounding the fields in order to avoid artificial transport pathways for pesticides and their degradation products from the surface to the groundwater. The vertical wells are located down- stream from the field (Fig. 2), except for one upstream verti- cal well, which is used to determine the upstream influx to the groundwater beneath the field. The horizontal wells are installed at the clayey till fields at depths of 2–3.5 m under the pesticide-treated areas, and at the sandy fields just be- neath the fluctuating groundwater table. Detection of pes- ticides or their degradation products can be directly related to the specific pesticide application to the PLAP fields by monitoring both the variably and fully saturated soil and accounting for potential upstream influx. In the drainage from the clayey till fields, the weighted average concentration of pesticides is based on flow-pro- portional sampling. In the two sandy soils, the weighted average pesticide concentration leached to the suction cups at 1 m depth is estimated from the detected concentrations and estimated percolation on a monthly basis (Brüsch et al. 2015). The analytical programme includes relevant pesticides and their degradation products as well as inorganic com- pounds such as chloride, nitrate, phosphate and bromide, Monitoring of pesticide leaching from cultivated fields in Denmark Walter Brüsch, Annette E. Rosenbom, Nora Badawi and Preben Olsen Silstrup Estrup Jyndevad Fårdrup Annual net precipitation < 150 mm 150–200 mm 200–250 mm 250–300 mm 300–350 mm 350–400 mm > 400 mm 100 km TylstrupSilstrup Estrup Jyndevad Tylstrup Faardrup Estrup Jyndevad Faardrup Clayey till field Sandy field Fig. 1. Annual net-precipitation in Denmark and the location of the five PLAP fields (http://www2.mst.dk/Udgiv/publikationer/1992/87-503 -9581-5/pdf/87-503-9581-5.pdf; Rosenbom et al. 2015). Tylstrup and Jyndevad are located in sandy areas with marine sand and glaciof luvial sand, respectively. Silstrup, Estrup and Faardrup are situated in areas dominated by clayey till, and the three fields are drained. The sedi- ments were deposited during and after the last glaciation. 1818 which is used as a tracer. The pesticides are generally anal- ysed for two years following application, but the monitoring continues if significant leaching occurs. To evaluate the pes- ticide leaching, the water balance, including the percolation through the variably saturated soil, is assessed for all five PLAP fields using the numerical model MACRO (Larsbo et al. 2005) based on long-term detailed monitoring of cli- mate, crop-growth, soil water content, groundwater table, and if present, drainage flow (Rosenbom et al. 2015). Monitoring results According to the legislation of the European Union, the maximum permissible concentration of any pesticide in groundwater is 0.1 μg/l (Council of the European Union 1994). This limit is not based on health investigations but was the analytical detection limit when the legislation was made in the 1980s, and was chosen to ensure that drink- ing water did not contain measurable amounts of pesti- cides. During the latest monitoring period from July 2012 to June 2014, a total of 7378 single analyses of different pesticides or their degradation products were carried out on water samples collected at the five sites. The leaching risk of 22 pesticides and 17 degradation products was evaluated after applying the specific pesticide on specific crops. Of these 39 pesticides and their degradation products, 21 were not detected in any of the water samples. During the entire monitoring period from May 1999 to June 2014, 51 pesticides and 52 degradation products were analysed. These are listed in the Appendix. The monitor- ing data showed leaching of 17 of the applied pesticides and their degradation products through the soil to tile drains or suction cups in average concentrations exceeding 0.1 μg/l. These are marked with asterisks in the Appendix. The results of the monitoring also showed leaching of an additional 17 pesticides, but in low concentrations, marked by † in the Appendix. Although the concentrations exceed- ed 0.1 μg/l in several water samples collected from suction cups and tile drains at 1 m depth, the average leaching concentrations did not exceed 0.1 μg/l on an annual basis. In groundwater samples, twenty-one pesticides or their degradation products were only detected at concentrations Table 1. Characteristics of the five pesticide leaching assessment fields Precipitation (mm/y)* 668 858 866 862 558 Potential evapotranspiration (mm/y)* 552 555 564 543 585 Area (ha) 1.1 2.4 1.7 1.3 2.3 Tile drain No No Yes Yes Yes Depth to tile drain (m) 1.1 1.1 1.2 Deposited by Saltwater Meltwater Glacier Glacier Glacier Sediment type Fine sand Coarse sand Clay till Clay till Clay till Topsoil classification Loamy sand Sand Sandy clay loam Sandy loam Sandy loam Tylstrup Jyndevad Silstrup Estrup Faardrup * Based on the period 1961–1990, modified from Lindhardt et al. (2001). 50 m Vertical monitoring screen Tile drain, inside field Tile drain, outside field Collector pipe Groundwater flow Sample point, horizontal screens Horizontal monitoring screen, 3.5 m depth Horizontal monitoring screen, 2 m depth 0 50 m10 m #1 Outlet Suction cup Rain gauge Buffer zone Farmed area Piezometer Fig. 2. Overview of the Silstrup field and its technical installations. 19 below 0.1μg/l or not at all. These are marked by § in the Appendix. At the three clayey till fields, several pesticides were de- tected in the drainage, whereas the frequency of detection in the groundwater monitoring screens beneath the tile drain system was lower and varied considerably between the three fields. In the two sandy fields, fewer pesticides and degradation products were generally detected, both in the variably saturated soil and in groundwater (Table 2). The different leaching patterns in the sandy and clayey till fields can be attributed to specific hydrological, geo- logical and geochemical conditions. The subsoil C horizon beneath the tile drains at the Estrup field shows low per- meability with few macropores (Kjær et al. 2005; Rosen- bom et al. 2015) in contrast to the Faardrup and Silstrup fields, where the clayey till is characterised by fractures and heterogeneity. Hence the fewer records of pesticides and degradation products in the groundwater at Estrup than at Faardrup and Silstrup can be related to the low perme- ability at the former site. A comparison between the clayey till fields shows that the number of water samples containing pesticides and degradation products was higher at Silstrup and Estrup (35 and 40%, respectively) than at Faardrup (15%). This can be attributed to different hydro-geochemical con- ditions and the low net precipitation at Faardrup. The leaching pattern for non-pesticides shows that the aver- age concentration of nitrate-N was much higher in both groundwater and drainage at Faardrup than at the other two fields (Table 2; Ernstsen et al. 2015). However, the average chloride content in both drainage and groundwater at Faardrup was higher than at Silstrup (Table 2), due to an up-concentration in the infiltration water caused by the low precipitation at Faardrup. The occurrence of precipita- tion and subsequent percolation within the first month af- ter application were generally higher at Silstrup and Estrup than at Faardrup (Table 1). At the clayey till fields, 59–78% of the different applied pesticides and their degradation products were detected in drainage water or groundwater (Table 2), while only 28–33% of them were detected at the sandy fields. High pesticide concentrations dominated at the three clayey till fields, with 33–53% of the detections exceeding 0.1 μg/l, while only 11–16% of the detections at the two sandy fields exceeded the threshold limit. However, the limit of 0.1 μg/l is only relevant for groundwater and not for drainage water. The average nitrate concentrations were high in the groundwater of the sandy fields and lower at the clayey till fields (Ernstsen et al. 2015). However, a high average ni- trate concentration was recorded in both the drainage and groundwater from the Faardrup field where the precipita- tion is low. This is probably because the uppermost part of the till is characterised by high permeability. It is therefore apparent that the pesticide and nitrate concentrations both reflect the geochemical conditions of groundwater and drainage water. Further details regarding PLAP can be found in Kjær et al. (2002, 2003, 2004, 2005, 2007, 2008, 2009, 2011), Rosenbom et al. (2010), Brüsch et al. (2013a, 2013b, 2015), Ernstsen et al. (2015) and Rosenbom et al. (2015). For fur- ther information please visit: http://pesticidvarsling.dk/mon- itor_uk/index.html. Conclusions The results presented here provide an overall picture of the detections of pesticides and their degradation products in soil and groundwater in five monitored cultivated fields representing typical Danish farming activities on clayey and sandy soils in the period from 1999 to 2014. The overall Table 2. Total number of pesticides analysed, detected, and detected below 0.1 μg/l in all sample types Pesticides Detections 16 19 39 45 38 and Detections >0.1 μg/l 6 9 22 31 21 metabolites Detections in % 28.1 32.8 59.1 77.6 66.7 >0.1 μg/l in % 10.5 15.5 33.3 53.4 36.8 Groundwater avg Nitrate-N 15.5 11.9 3.0 0.4 8.5 Chloride 49.9 15.6 29.5 11.7 27.1 Drainage avg Nitrate-N ns ns 2.1 3.5 11.2 Chloride ns ns 30.3 26.6 27.5 Fine-grained sand Coarse-grained sand Clayey till Tylstrup Jyndevad Silstrup Estrup Faardrup Samples collected from suction cups, drainage and groundwater in the five PLAP fields between 01 January 2000 and July 2012. Average nitrate and chloride concentrations from groundwater and drainage in the period January 2011 – July 2012. Avg: average concentration in mg/l. ns: no samples. 2020 pesticide leaching detected in the monitoring programme is an outcome of the pesticide selection, hydraulic condi- tions, type of agriculture and the geochemical conditions such as the redox potential, aerobic conditions and hence the leaching of nitrate-N and potential persistence of indi- vidual pesticides. For instance, the leaching of pesticides is more pronounced in fractured clayey soils than in sandy soils due to fast transport in anaerobic fractures in the for- mer soils, in contrast to slower matrix transport in the more aerated sandy soils. This is illustrated by the high number of recorded pesticides in drainage water and groundwater from clayey till soils due to bypassing of the topsoil by rapid leaching through well-connected macropores such as wormholes and fractures (Rosenbom et al. 2015). The oc- currence of pesticides in samples from the two sandy soils is probably specifically linked to the application of persistent pesticides such as metalaxyl-M applied to potatoes. References Brüsch, W., Kjær, J., Rosenbom, A.E., Juhler, R.K., Gudmundsson, L., Plauborg, F., Nielsen, C.B. & Olsen, P. 2013a: The Danish Pesticide Leaching Assessment Programme: Monitoring results May 1999 – June 2011, 108 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Brüsch, W., Rosenbom, A.E., Juhler, R.K., Gudmundsson, L., Plauborg, F., Nielsen, C.B. & Olsen, P. 2013b: The Danish Pesticide Leaching Assessment Programme: Monitoring results May 1999 – June 2012, 106 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Brüsch, W., Rosenbom, A.E., Badawi, N., v. Platten-Hallermund, F., Gudmundsson, L., Plauborg, F., Nielsen, C.B., Laier, T. & Olsen, P. 2015: The Danish Pesticide Leaching Assessment Programme: Moni- toring results May 1999 – June 2013, 110 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Council of the European Union 1994: Council Directive 94/43/EC es- tablishing Annex VI to Directive 91/414/EEC concerning the placing of plant protection products on the market. Official Journal of the European Union L227, 1.9.1994, 31–55. Ernstsen, V., Olsen, P. & Rosenbom, A.E. 2015: Long-term monitor- ing of nitrate transport to drainage from three agricultural clayey till fields. Hydrology and Earth System Sciences 19, 3475–3488, http:// dx.doi.org/10.5194/hess-19-3475-2015. Kjær, J. et al. 2002: The Danish Pesticide Leaching Assessment Pro- gramme: Monitoring results May 1999 – June 2001, 150 pp. Copen- hagen, Denmark: Geological Survey of Denmark and Greenland. Kjær, J., Ullum, M., Olsen, P., Sjelborg, P., Helweg, A., Mogensen, B., Plauborg, F., Grant, R., Fomsgaard, I. & Brüsch, W. 2003: The Dan- ish Pesticide Leaching Assessment Programme: Monitoring results May 1999 – June 2002, 158 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Kjær, J., Olsen, P., Barlebo, H.C., Juhler, R.K., Plauborg, F., Grant, R., Gudmundsson, L. & Brüsch, W. 2004: The Danish Pesticide Leach- ing Assessment Programme: Monitoring results May 1999 – June 2003, 146 pp. Copenhagen, Denmark: Geological Survey of Den- mark and Greenland. Kjær, J., Olsen, P., Barlebo, H.C., Juhler, R.K., Henriksen, T., Plauborg, F., Grant, R., Nyegaard P. & Gudmundsson, L. 2005: The Danish Pesticide Leaching Assessment Programme: Monitoring results May 1999 – June 2004, 86 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Kjær, J., Olsen, P., Barlebo, H.C., Henriksen T., Plauborg, F., Grant, R., Nyegaard, P., Gudmundsson, L. & Rosenbom, A.E. 2007: The Dan- ish Pesticide Leaching Assessment Programme: Monitoring results May 1999 – June 2006, 99 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Kjær, J., Rosenbom, A., Olsen, P., Juhler, R.K., Plauborg, F., Grant, R., Nyegaard, P., Gudmundsson, L. & Brüsch, W. 2008: The Danish Pesticide Leaching Assessment Programme: Monitoring results May 1999 – June 2007, 91 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Kjær, J., Rosenbom, A., Olsen, P., Ernstsen, V., Plauborg, F., Grant, R., Nyegaard, P, Gudmundsson, L. & Brüsch, W. 2009: The Danish Pesticide Leaching Assessment Programme: Monitoring results May 1999 – June 2008, 88 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Kjær, J., Rosenbom, A.E., Olsen, P., Ernstsen, V., Plauborg, F., Grant, R., Gudmundsson, L. & Brüsch, W. 2011: The Danish Pesticide Leaching Assessment Programme: Monitoring results May 1999 – June 2010, 110 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Larsbo, M., Roulier, S., Stenemo, F., Kasteel, R. & Jarvis, N. 2005: An improved dual-permeability model of water f low and solute transport in the vadose zone. Vadose Zone Journal 4, 398–406. Lindhardt, B., Abildtrup, C., Vosgerau, H., Olsen, P., Torp, S., Iversen, B.V., Jørgensen, J.O., Plauborg, F., Rasmussen, P. & Gravesen, P. 2001: The Danish Pesticide Leaching Assessment Programme: Site characterization and monitoring design, 73 pp. Copenhagen, Den- mark: Geological Survey of Denmark and Greenland. Rosenbom, A.E., Brüsch, W., Juhler, R.K., Ernstsen, V., Gudmundsson, L., Plauborg, F., Grant, R. & Olsen, P. 2010: The Danish Pesticide Leaching Assessment Programme: Monitoring results May 1999 – June 2009, 102 pp. Copenhagen, Denmark: Geological Survey of Denmark and Greenland. Rosenbom, A.E., Olsen, P., Plauborg, F., Grant, R., Juhler, R.K., Brusch, W. & Kjaer, J. 2015: Pesticide leaching through sandy and loamy fields – long-term lessons learnt from the Danish Pesticide Leaching Assessment Programme. Environmental Pollution 201, 75–90. Authors’ addresses W.B.*, A.E.R. & N.B., Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark. P.O., Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark. *Present address: Danmarks Naturfredsningsforening, Madsnedøgade 20, DK-2100 Copenhagen Ø, Denmark. E-mail: wb@dn.dk 21 Appendix. PLAP analyses from May 1999 to June 2014. Part A Aclonifen Aclonifen † 111 § 298 Amidosulfuron Amidosulfuron 144 3 1 0.11 § 332 Desmethyl-amidosulfuron 24 88 Aminopyralid Aminopyralid † 133 § 261 Azoxystrobin Azoxystrobin * 717 139 16 1.4 1798 3 0.04 CyPM * 740 390 144 2.1 1910 69 5 0.19 Bentazone Bentazone * 1051 350 43 43 2603 81 8 0.6 2-amino-N-isopropyl-benzamide 561 4 0.06 1295 1 0.02 Bifenox Bifenox 303 17 3 0.38 751 7 1 0.1 Bifenox acid * 278 55 47 8.6 702 29 23 3.1 Nitrofen 303 11 4 0.34 751 Boscalid Boscalid † 56 § 111 Bromoxynil Bromoxynil 528 5 3 0.6 § 1122 Chlormequat Chlormequat † 95 2 0.017 § 190 Clomazon Clomazone 224 1 1 0.28 § 598 FMC 65317 216 1 1 0.3 577 Clopyralid Clopyralid 219 7 4 4.094 § 520 1 0.026 Cyazofamid Cyazofamid † 100 § 262 Desmedipham Desmedipham † 287 580 1 0.033 EHPC 199 383 Diflufenican Diflufenican 109 32 14 0.49 324 1 1 0.47 AE-B107137 * 121 19 1 0.13 333 1 0.016 AE-05422291 109 324 Dimethoate Dimethoate † 515 1 1 1.417 1253 1 0.085 Epoxiconazole Epoxiconazole 330 14 2 0.39 999 1 0.011 Ethofumesate Ethofumesate * 519 70 17 12 1095 36 7 1.4 Fenpropimorph Fenpropimorph † 657 2 0.038 1531 2 0.029 Fenpropimorph acid 636 2 1 0.25 1435 Flamprop-M Flamprop-M-isopropyl 520 38 1 0.109 1204 1 0.024 Flamprop 525 23 1 0.35 1212 Florasulam Florasulam † 146 351 Florasulam-desmethyl 109 130 Fluazifop-P-buthyl Fluazifop-P-butyl 128 232 TFMP * 184 53 24 0.64 555 87 16 0.29 Fluazifop-P 451 11 4 3.8 1109 7 1 0.17 Fludioxonil CGA 192155 † 11 § 48 CGA 339833 11 48 Fluroxypyr Fluroxypyr * 521 4 3 1.4 1273 2 0.072 Glyphosate Glyphosate * 1091 429 136 31 2216 77 5 0.67 AMPA * 1092 632 142 5.4 2217 37 0.08 Iodosulfuron-methyl-natrium Metsulfuron-methyl 332 1 0.054 842 Iodosulfuron-methyl † 60 § 250 Ioxynil Ioxynil 527 24 7 0.25 1128 1 0.01 Linuron Linuron † 67 § 271 Mancozeb ETU 44 7 0.038 200 2 0.024 EBIS 7 25 MCPA MCPA 354 14 3 3.894 916 1 0.019 2-methyl-4-chlorophenol 354 2 1 0.24 912 Mesosulfuron-isopropyl Mesosulfuron-methyl 153 13 0.059 § 411 Mesosulfuron 119 119 Mesotrione Mesotrione † 50 § 156 AMBA 50 156 MNBA 50 156 Pesticide Analyte Tile drain and suction cup Groundwater Samples Det. ≥0.1 Max. Samples Det. ≥0.1 Max. Fifty-one pesticides and 52 degradation products analysed in the PLAP programme in the period May 1999 – June 2014. The columns show the number of water samples analysed, number of detections, and detections in concentrations ≥ 0.1μg/l in water samples from the variably-saturated zone (drainage and suction cups), and in groundwater (vertical and horizontal groundwater wells). Det: number of detections. ≥0.1: number of detections ≥0.1μg/l. Max: maximum concentration in μg/l. *: Pesticides and their degradation products leached through soil to tile drains or suction cups in average concentrations above 0.1 μg/l. †: Pesticides not detected or detected only in a few samples above their threshold concentrations at 1 m depth. §: Pesticides and their degradation products not detected or only detected in a few samples in groundwater. 2222 Appendix. PLAP analyses from May 1999 to June 2014. Part B Metalaxyl-M metalaxyl-M 207 15 0.037 592 79 23 1.3 CGA 108906 * 215 175 69 4.8 593 468 128 2.7 CGA 62826 * 216 100 25 1.2 593 147 8 0.68 Metamitron Metamitron * 515 103 31 26.369 1095 53 7 0.63 Desamino-metamitron * 518 129 23 5.549 1094 78 16 1.3 Metrafenone Metrafenone 136 20 0.072 273 1 0.04 Metribuzin Metribuzin 97 2 0.024 414 1 0.014 Diketo-metribuzin 340 256 63 0.69 552 479 336 1.372 Desamino-diketo-metribuzin * 255 81 51 2.1 551 256 18 1.831 Desamino-metribuzin * 91 392 Pendimethalin Pendimethalin 694 89 30 32 1811 1 0.052 Phenmedipham Phenmedipham 288 580 2 0.025 MHPC 288 2 1 0.19 580 1 0.053 3-aminophenol 109 245 Picolinafen Picolinafen 117 18 0.07 193 CL153815 * 117 31 11 0.5 193 Pirimicarb Pirimicarb 887 62 0.077 2120 6 0.035 Pirimicarb-desmethyl-formamido * 707 29 13 0.379 1638 2 0.076 Pirimicarb-desmethyl 780 8 0.053 1911 3 0.042 Propiconazol Propiconazole 899 32 3 0.862 2084 3 0.035 Propyzamid Propyzamide * 257 27 8 1.6 754 10 2 0.14 RH-24644 257 19 0.051 754 2 0.032 RH-24580 257 2 0.016 754 RH-24655 233 1 0.017 690 Prosulfocarb Prosulfocarb 199 6 1 0.18 516 5 0.032 Pyridat Pyridate 39 116 PHCP 125 4 4 2.69 373 14 4 0.309 Rimsulfuron Rimsulfuron 117 367 PPU * 502 388 74 0.29 1519 432 13 0.23 PPU-desamino 502 186 6 0.18 1519 107 0.089 Tebuconazole Tebuconazole * 289 47 17 2 784 8 2 0.12 1.2.4-triazol * 16 7 1 0.17 Terbuthylazine Terbuthylazine * 513 213 56 11 1324 88 23 1.9 Desethyl-terbuthylazine * 612 365 88 8.3 1664 261 33 0.94 Desisopropylatrazine 414 156 2 0.44 996 92 0.047 Hydroxy-terbuthylazine * 384 136 18 0.99 940 34 0.069 2-hydroxy-desethyl-terbuthylazine * 342 128 28 6.3 850 9 0.092 Thiacloprid Thiacloprid † 47 § 100 Thiacloprid-amide 47 1 0.012 100 M34 55 100 Thiacloprid sulfonic acid 56 100 Thiamethoxam Thiamethoxam † 132 § 359 CGA 322704 132 359 Triasulfuron Triasulfuron † 82 § 301 Triazinamin 393 1103 1 0.042 Tribenuron-methyl Triazinamin-methyl † 569 2 0.042 § 1523 Triflusulfuron-methyl Triflusulfuron-methyl † 95 288 IN-E7710 95 5 0.014 288 IN-M7222 95 288 1 0.052 IN-D8526 95 288 Pesticide Analyte Tile drain and suction cup Groundwater Fifty-one pesticides and 52 degradation products analysed in the PLAP programme in the period May 1999 – June 2014. The columns show the number of water samples analysed, number of detections, and detections in concentrations ≥ 0.1μg/l in water samples from the variably-saturated zone (drainage and suction cups), and in groundwater (vertical and horizontal groundwater wells). Det: number of detections. ≥0.1: number of detections ≥0.1μg/l. Max: maximum concentration in μg/l. *: Pesticides and their degradation products leached through soil to tile drains or suction cups in average concentrations above 0.1 μg/l. †: Pesticides not detected or detected only in a few samples above their threshold concentrations at 1 m depth. §: Pesticides and their degradation products not detected or only detected in a few samples in groundwater. Samples Det. ≥0.1 Max. Samples Det. ≥0.1 Max.