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Establishment of a basis for administrative use of PestSurf

Annex 8

8 Comparison of risk assessment data produced by spray drift assessments, FOCUS SW and PestSurf

8.1 Chemical characteristics of the compound

Table 8.1. Overview of chemical properties of propiconazol and the parameters used in the simulations.
Tabel 8.1. Oversigt over propiconazol s kemiske egenskaber og parametrene brugt i simuleringerne.

8.2 Concentration generated by spray

8.3 Concentrations generated by FOCUS SW

8.3.1 D3- Ditch

8.3.2 D4 – Pond

8.3.3 D4 –Stream

8.3.4 Conclusion – FOCUS SW

The highest concentration is generated in the ditch (D3). It is caused by wind drift and the concentration becomes 0.792 µg/l. The same scenario shows the highest concentration in the sediment, 0.437 µg/l. For all scenarios, the concentrations are lower than what is generated by the simpler assessments.

8.4 PestSurf

8.4.1 Sandy Catchment, stream

The distribution of concentrations were assessed in several steps. First, the maximum concentrations at each calculation point were listed, and the dates for the occurrence of the maximum was assessed. The points, for which the maximum value also represents a local maximum were selected for further analysis. The relevant values are listed in Table 8.2.

Table 8.2. Maximum concentrations (ng/l) of propiconazol simulated for each calculation point in the sandy catchment.
Tabel 8.2. Maximumkoncentrationer (ng/l) af propiconazol simuleret for hvert beregningspunkt i det sandede opland.

The pattern over time was dominated by spraydrift contribution for all calculation points. The pattern is identical all through the stream, see Figure 8.1. There are only small differences between years.

Figure 8.2 shows the longitudinal profile of the stream on the date of maximum concentration of the stream in the sandy catchment. The thin black line represents the concentration, while the thick black line shows the maximum concentrations obtained during the simulations. In addition, the outline of the stream is shown.

Figure 8.1. Concentration pattern over time for propiconazol in the sandy catchment.
Figur 8.1. Koncentrationsmønster som funktion af tid for propiconazol i det sandede opland.

Figure 8.2. Concentrations of propiconazol in the sandy catchment on 4. June 1998 just after spraying.
Figur 8.2. Koncentrationer propiconazol i det sandede opland den 4. juni 1998 lige efter endt sprøjtning.

In order to present the data in a similar fashion to the FOCUS SW-results, data were extracted and recalculated for the time series marked in Table 8.2. The global maxima and time weighted concentrations (up to 7 days) were extracted and are reported in Table 8.3. Note that the unit is ng/l.

Table 8.3. Instantaneous and time weighted concentrations (ng/l) of propiconazol in the sandy catchment.
Tabel 8.3. Beregnet og tidsvægtet koncentration af propiconazol, ng/l, på udvalgte lokaliteter i det sandede vandløb.

Click here to see Table 8.3.

Sorption to macrophytes are shown in Figure 8.3. The maximum value reached is 42 ng/l, and the concentration is thus somewhat lower than the concentration in the water phase. The concentration in pore water is shown in Figure 8.4. The concentration is very low and the concentration of propiconazol adsorbed to sediment is 3 ng/kg (Figure 8.5).

Figure 8.3. Concentration of propiconazol adsorbed to macrophytes.
Figur 8.3. Koncentration af propiconazol sorberet på makrofytter.

Figure 8.4. Pore water concentration of propiconazol in the sandy catchment. The maximum value of 0.039 ng/l is reached 1421 m from the upstream end.
Figur 8.4. Porevandskoncentration for propiconazol i det sandede opland. Maximumskoncentrationen på 0.039 ng/l opnås 1421 m fra den opstrøms ende.

Figure 8.5. Concentration of propiconazol in sediment in the sandy catchment. The maximum value of 2.67 ng/kg is reached 1421 m from the upstream end. Note that the unit is µg/kg and not µg/m³ as indicated.
Figur 8.5. Koncentration af propiconazol i sediment i det sandede opland. Maximumskoncentrationen på 2.67 ng/kg opnås 1421 m fra den opstrøms ende. Bemærk at koncentrationen er i µg/g og ikke i µg/m³ som angivet.

The global maximum value calculated by PestSurf for the sandy catchment in the water phase is 3.42 µg/l. This is considerably more than what is found in the D3-ditch scenario (0.792 µg/l). However, 100 m from the upstream end, the concentration reached in PestSurf is 0.245 µg/l, which is more comparable to the D3-ditch. The high concentrations reached are a function of the simultaneous spraying of all agricultural land within 30 min.

Limited sorption to macrophytes and to sediment was found in PestSurf. FOCUS SW D3 ditch predicts a sediment concentration of 0.437 µg/kg.

Figure 8.6 shows the output of the PestSurf Excel template. The template works with pre-defined data extraction points. The plot requires specification of a “lowest detection value” (ldc) which defines when a pesticide occurrence is defined as an event. The time series plot is identical to the time series shown earlier, and the graph in the upper right corner resembles the plot in Figure 8.2, but takes into account a longer period of time. A curve is generated when a downstream point reaches a concentration higher than the ldc. The programme then tracks the highest concentration for each calculation point in the stream within the last 24 hours. The plot in the lower right corner shows how many events have concentrations higher than a given toxicity value for the selected monitoring points. The curves are rather flat, showing little variation from year to year.

Table 8.4 shows part of the result sheet generated by the PestSurf Excel sheet based on the ldc-value. The selected table shows the point along the stream (of the pre-defined points) with the highest concentration. The highest concentration extracted by the PestSurf Excel sheet was 1.88 µg/l. which is somewhat lower than the maximum concentration of the simulation, 3.42 µg/l. Thus the template did not catch the maximum concentration.

Click here to see Figure 8.6.

Figure 8.6. Overview for propiconazol in the sandy catchment generated by the PestSurf excel template. The max concentrations generated over the 24 hours are similar to the overview in Figure 8.2. Detection value was set to 1 ng/l.
Figur 8.6. Oversigt for propiconazol i det sandede opland genereret med PestSurf-excel-skabelonen. Den maximale koncentration genereret over 24 timer svarer til oversigten i Figur 8.2. Detektionsgrænsen var sat til 1 ng/l.

Table 8.4. Part of the result sheet generated by the PestSurf Excel sheet. The selected table shows the point along the stream with the highest concentration recorded. The lowest detection value is 1 ng/l, toxicity to fish, daphnies and algae are set to 10, 100 and 1000 ng/, respectively. The recorded peaks are shown in Figure 8.6.
Tabel 8.4. Uddrag af resultatpresentationen genereret af PestSurf-Excel-arket. Den udvalgte tabel viser det fordefinerede punkt langs med åen med højest koncentration. Detektionsgrænsen er sat til 1 ng/l mens toxicitetsværdierne for fisk, dafnier og alger er henholdsvis 10, 100 og 1000 ng/l. De tabellerede hændelser er vist i Figur 8.6.

Click here to see Table 8.4.

8.4.2 Sandy Catchment, pond

The concentration pattern is evaluated in the middle of the pond only, see Figure 8.7. The pond receives the major contribution from groundwater. The drift peaks are not visible. The maximum concentration is 55 ng/l, and occurs at the beginning of autumn after a very dry summer.

Figure 8.7. Concentrations of propiconazol in the sandy pond.
Figur 8.7. Koncentration af propiconazol i det sandede vandhul.

In Table 8.5, global maxima and time weighted concentrations (up to 7 days) were extracted.

Table 8.5. Maximum concentrations (ng/l) of propiconazol generated by drift and baseflow for the sandy pond.
Tabel 8.5. maximumkoncentrationer af propiconazol(ng/l) genereret for det sandede vandhul.

The sorption of propiconazol to macrophytes is shown in Figure 8.8. The amount of sorption is limited and does not significantly affect the concentration in the water phase. The porewater concentration reaches a concentration of 2.6 ng/l, coinciding with the highest concentration in the pond, see Figure 8.9. Figure 8.10 shows the concentration of propiconazol adsorbed to sediment. The maximum amount is 60 ng/kg.

Figure 8.8. Sorption of propiconazol to macrophytes in the sandy pond
Figur 8.8. Sorption af propiconazol til makrofytter i det sandede vandhul.

Figure 8.9. Pore water concentration of propiconazol in the sandy pond.
Figur 8.9. Porevandskoncentration af propiconazol i det sandede vandhul.

Figure 8.10. Sorption of propiconazol to sediment in the sandy pond. The concentration is in µg/g sediment and not µg/m³ as stated.
Figur 8.10. Sorption af propiconazol til sediment i det sandede vandhul. Koncentrationen er i µg/g og ikke i µg/m³ som angivet.

Compared to the FOCUS D3-ditch, the concentration in the PestSurf sandy pond is lower, 0.055 µg/l compared to 0.792 µg/l. Similarly the concentration in sediment is much lower, 0.060 µg/kg compared to 0.437 µg/kg.

Figure 8.11 shows the output of the PestSurf Excel template. The template works with one pre-defined data extraction point for the pond (center of the pond). The plot requires specification of a “lowest detection value” (ldc) which defines when a pesticide occurrence is defined as an event. The time series plot is identical to the time series shown earlier. The plot in the right corner shows how many events have concentrations higher than a given toxicity value for the selected monitoring points.

Table 8.6 shows part of the result sheet generated by the PestSurf Excel sheet based on the ldc-value.

Click here to see Figure 8.11.

Figure 8.11. Overview for propiconazol in the sandy pond generated by the PestSurf excel template. The time series shown is identical to the one in Figure 8.7. The lowest detection value used for the graph is 20 ng/l.
Figur 8.11. Oversigt for propiconazol i det sandede vandhul genereret med PestSurf-excel-skabelonen. Den viste tidsserie er mage til den i Figur 8.7. Detektionsgrænsen er sat til 20 ng/l.

Table 8.6. Part of the result sheet generated by the PestSurf Excel sheet. The lowest detection value for generation of the table is 20 ng/l, toxicity to fish, daphnies and algae are set to 25, 30 and 40 ng/, respectively. The recorded peaks are shown in Figure 8.11.
Tabel 8.6. Uddrag af resultatpresentationen genereret af PestSurf-Excel-arket. Grænseværdien anvendt til tabelgenerering er sat til 20 ng/l mens toxicitetsværdierne for fisk, dafnier og alger er henholdsvis 25, 30 og 40 ng/l. De tabellerede hændelser er vist i Figur 8.11.

Click here to see Table 8.6.

8.4.3 Sandy Loam Catchment, stream

The distribution of concentrations was assessed in several steps. First, the maximum concentrations at each calculation point were listed, and the dates for the occurrence of the maximum was assessed (Table 8.7). The points, for which the maximum value also represents a local maximum were selected for further analysis.

Table 8.7. Maximum concentrations (ng/l) of propiconazol simulated for each calculation point in the sandy loam catchment.
Tabel 8.7. Maximumskoncentrationer (ng/l) af propiconazol simuleret for hvert beregningspunkt i morænelersoplandet.

All maximum concentrations are caused by drift events. Two selected time series are shown in Figure 8.12 and Figure 8.13, representing the upstream and downstream end of the system, respectively. The upstream end of the system is dominated by drift, but the extreme rainfall event around 16-17. September 1998 is visible in most points. Due to a rather low degradation rate (a DT50 value around 62 days) there is a limited degree of buildup in the downstream end of the stream. The drift contribution is high, due to the simultaneous spraying of the whole agricultural area within 30 minutes.

a)

b)

Figure 8.12. Concentration pattern for propiconazol in OvreLillebaek (290 m and 625 m from upstream), in the upper end of the sandy loam catchment.
Figur 8.12. Koncentrationsmønster for propiconazol i Øvre Lillebæk (290 m og 625 m fra opstrøms ende ) i den øvre del af morænelersoplandet.

Figure 8.13. Concentration pattern for propiconazol in the lower part of the sandy loam catchment.
Figur 8.13. Koncentrationsmønster for propiconazol i i den nedre del af morænelersoplandet.

Longitudinal profiles of the concentrations in the sandy loam catchment on selected dates (31. May 1998 and 31. May 2000) are shown in Figure 8.14 to Figure 8.18. For the last date, four figures shows how the peaks move downstream. The thin black line represents the concentration, while the thick black line shows the maximum concentrations obtained during the simulations. In addition, the outline of the stream is shown.

Figure 8.14. Concentrations in the sandy loam catchment on 31. May 1998, just after spraying.
Figur 8.14. Koncentrationer i morænelersoplandet den 31. maj-1998, lige efter sprøjtning.

Figure 8.15. Concentrations in the sandy loam catchment on 31. May 2000 at 8.30 hours, just after spraying.
Figur 8.15. Koncentrationer i morænelersoplandet den 31. maj-2000, 8.30, lige efter sprøjtning.

Figure 8.16. Concentrations in the sandy loam catchment on 31. May 2000 at 8.40 hours.
Figur 8.16. Koncentrationer i morænelersoplandet den 31. maj-200, kl. 8.40.

Figure 8.17. Concentrations in the sandy loam catchment on 31. May 2000 at 8.50 hours.
Figur 8.17. Koncentrationer i morænelersoplandet den 31. maj-200, kl. 8.50.

Figure 8.18. Concentrations in the sandy loam catchment on 31. May 2000 at 10.00 hours.
Figur 8.18. Koncentrationer i morænelersoplandet den 31. maj-200, kl. 10.00.

To be able to extract comparable values to FOCUS SW, the global maxima and time weighted concentrations (up to 7 days) were extracted when these were meaningful.

Figure 8.19 and Figure 8.20 show the concentrations sorbed to macrophytes. The maximum value reached is 646 ng/l. The concentration is relatively low compared to the concentration in the water phase. The pattern follows the pattern of the water concentrations.

The concentration of propiconazol in porewater in the sediment reached 17 ng/l the lower end of the catchment, see Figure 8.21. Concentrations in sediment is shown in Figure 8.22. A maximum value of 339 ng/kg is reached.

The FOCUS SW D4-stream-scenario generates a concentration of 0.657 µg/l, while the PestSurf simulation reaches 11.786 µg/l. In both simulations, the maximum concentrations are generated by wind drift.

The maximum concentrations in PestSurf are reached because a long stretch of stream receives drift simultaneously. 100 m from the upstream end, a concentration of 4.5 µg/l is reached. The water depth at this time is only about 5 cm in 1998 and 3.5 cm in 2000. There is therefore a factor of 6-9 hidden in the difference in water depth alone.

The sediment concentration of 339 ng/kg is about 3 times the concentration generated by FOCUS SW-D4 stream (102 ng/kg).

Figure 8.23, Figure 8.24, Table 8.9 and Table 8.10 show the results as generated by the PestSurf templates. The maximum value generated by the templates for the upper part of the stream is 4.28 µg/l, and for the lower part, 11.8 µg/l. The maximum value generated by PestSurf in the upstream part of the catchment is 6.10 µg/l in OvreLillebaek and in the lower part 11.8 µg/l. The templates thus captures the maximum concentration in the lower part but not in the upper part of the catchment.

Figure 8.19. Concentration on macrophytes in ng/l 290 m from the upstream end. The pattern is representative of the upper part of the sandy loam catchment.
Figur 8.19. Koncentration på makrofytter 290 m fra den opstrøms ende af morænelersoplandet. Mønsteret representerer hele åen.

Figure 8.20. Concentration on macrophytes in ng/l in the lower part of the sandy loam catchment.
Figur 8.20. Koncentration på makrofytter i den nedstrøms ende af morænelersoplandet. Mønsteret representerer hele åen.

Figure 8.21. Pore water concentration of propiconazol in the sandy loam catchment.
Figur 8.21. Porevandskoncentration af propiconazol i morænelersoplandet.

Figure 8.22. Sorption of propiconazol to sediment in the sandy loam catchment. The concentration is in µg/g sediment and not µg/m³ as stated.
Figur 8.22. Sorption af propiconazol til sediment i morænelersoplandet i Koncentrationen er i µg/g sediment og ikke µg/m³ som angivet.

Table 8.8. Instantaneous and time weighted concentrations (ng/l)of propiconazol for selected points in the sandy loam catchment.
Tabel 8.8. Beregnede og tidsvægtede maximumskoncentrationer (ng/l) af propiconazol for udvalgte lokaliteter i morænelersoplandet.

Click here to see Table 8.8.

Click here to see Figure 8.23.

Figure 8.23. Overview for propiconazol for the upstream part of the sandy loam catchment generated by the PestSurf excel template. The detection value was set to 1 ng/l.
Figur 8.23. Oversigt for propiconazol i den opstrøms del af morænelersoplandet genereret med PestSurf-excel-skabelonen. Detektionsgrænsen var sat til 1 ng/l.

Click here to see Figure 8.24.

Figure 8.24. Overview for propiconazol in the downstream part of the sandy loam catchment generated by the PestSurf excel template. The detection value was set to 300 ng/l.
Figur 8.24. Oversigt for propiconazol i den nedstrøms del af morænelersoplandet genereret med PestSurf-excel-skabelonen. Detektionsgrænsen var sat til 300 ng/l.

Table 8.9. Part of the result sheet generated by the PestSurf Excel sheet for the upstream part of the sandy loam catchment. The lowest detection value is 1 ng/l, toxicity to fish, daphnies and algae are set to 10, 100 and 1000 ng/, respectively. The recorded peaks are shown in Figure 8.23.
Tabel 8.9. Uddrag af resultatpresentationen genereret af PestSurf-Excel-arket for den opstrøms del af morænelersoplandet. Detektionsgrænsen for tabelgenerering er sat til 1 ng/l. Toxicitetsværdierne for fisk, dafnier og alger er henholdsvis 10, 100 og 1000 ng/l. Hændelserne er vist i Figur 8.23.

Click here to see Table 8.9.

Table 8.10. Part of the result sheet generated by the Pestsurf Excel sheet for the downstream part of the sandy loam catchment. The lowest detection value is 300 ng/l, toxicity to fish, daphnies and algae are set to 1000, 5000 and 10000 ng/, respectively. The recorded peaks are shown in Figure 8.24.
Tabel 8.10. Uddrag af resultatpresentationen genereret af PestSurf-Excel-arket for den nedstrøms del af morænelersoplandet. Detektionsgrænsen for tabelgenerering er sat til 300 ng/l. Toxicitetsværdierne for fisk, dafnier og alger er henholdsvis 1000, 5000 og 10000 ng/l. Hændelserne er vist i Figur 8.24.

Click here to see Table 8.10.

8.4.4 Sandy Loam Catchment, pond

The concentration pattern is evaluated in the middle of the pond only, see Figure 8.25. The pond receives contributions mainly through drift, in good correspondence with the fact that it is situated in the upper part of the sandy loam catchment. The concentration generated by drift is concentrated during the summer due to evaporation. The maximum concentration becomes 171 ng/l.

Figure 8.25. Concentrations of propiconazol for the sandy loam pond.
Figur 8.25. Koncentration af propiconazol i morænelersvandhullet.

Figure 8.26 shows the concentration of propiconazol on macrophytes in the pond. It follows the concentration pattern in the water phase, the maximum concentration reaching around 9.1 ng/l. The pore water concentration reaches 1.6 ng/l, see Figure 8.27. The concentration of propiconazol adsorbed to sediment is shown in Figure 8.28. The maximum value reached is 36.7 ng/kg.

In Table 8.11, global maxima and time weighted concentrations (up to 7 days) are extracted.

Figure 8.26. Propiconazol sorbed to the macrophytes in the sandy loam pond.
Figur 8.26. Propiconazol sorberet til makrofytter i morænelersvandhullet.

Figure 8.27. Pore water concentration of propiconazol in the sandy loam pond.
Figur 8.27. Porevandskoncentration af propiconazol i morænelersvandhullet.

Figure 8.28. Propiconazol sorbed to sediment in the sandy loam pond. Note that the concentration is µg/g sediment and not µg/m³ as indicated.
Figur 8.28. Propiconazol sorberet til sediment i morænelersoplandet i Bemærk at enheden er µg/g sediment og ikke µg/m³ som angivet.

Table 8.11. Actual and time weighted concentrations (ng/l) of propiconazol in the sandy loam pond.
Tabel 8.11. Beregnede og tidsvægtede koncentrationer (ng/l) af propiconazol i morænelersvandhullet.

Figure 8.29 and Table 8.12 show output from the PestSurf template, with a time series identical to Figure 8.25.

Compared to the FOCUS SW-scenario D4- pond the concentration levels generated by PestSurf are higher; 171 ng/l compared to 30 ng/l. The ponds differ in size, and that factor alone accounts for part of the difference. The difference in water depth accounts for the rest. The fact that the pond evaporates during the summer leads to an increase in concentration, which is not seen in the FOCUS simulations.

The sediment concentrations differ substantially between the two models, 290 ng/kg in FOCUS SW D4-pond and 37 ng/kg in the PestSurf simulation.

Click here to see Figure 8.29.

Figure 8.29. Overview for propiconazol in the sandy loam pond generated by the PestSurf excel template. The time series shown is identical to the one in Figure 8.25. The detection value was set to 50 ng/l.
Figur 8.29. Oversigt for propiconazol i morænelersvandhullet genereret med PestSurf-excel-skabelonen. Den viste tidsserie er mage til den i Figur 8.25. Detektionsgrænsen er sat til 1 ng/l.

Table 8.12. Part of the result sheet generated by the PestSurf Excel sheet. The lowest detection value is 50 ng/l, toxicity to fish, daphnies and algae are set to 100, 500 and 1000 ng/, respectively. The recorded peaks are shown in Figure 8.29.
Tabel 8.12. Uddrag af resultatpresentationen genereret af PestSurf-Excel-arket. Detektionsgrænsen er sat til 50 ng/l. Toxicitetsværdierne for fisk, dafnier og alger er henholdsvis 100, 500 og 1000 ng/l. De tabellerede hændelser er vist i Figur 8.29.

Click here to see Table 8.12.

Table 8.13. Summary of simulation results for propiconazol.
Tabel 8.13. Opsummerede resultater for propiconazol.

Click here to see Table 8.13.

8.5 Summary of simulations

The maximum actual concentrations for all simulations are recorded in Table 8.13.

For the sandy conditions, the PestSurf sandy pond generates lower concentrations than the ditch, which again generates lower concentrations than the stream. The global maximum value calculated by PestSurf for the sandy catchment in the water phase is 3.42 µg/l compared to 0.792 µg/l in the D3-ditch scenario. The high concentrations reached are a function of the simultaneous spraying of all agricultural land within 30 min. However, 100 m from the upstream end, the concentration reached in PestSurf is 0.245 µg/l, which is more comparable to the D3-ditch. These values are, however, not directly comparable as the top end of the sandy stream is protected by a 20 m buffer zone. The water depth at the time of maximum concentration is about 7 cm.

Compared to the FOCUS SW D4- pond the concentration levels generated by PestSurf are higher; 171 ng/l compared to 30 ng/l. The ponds differ in size, and that factor alone accounts for part of the difference. The difference in water depth accounts for the rest. The fact that the pond evaporates during the summer leads to an increase in concentration, which is not seen in the FOCUS simulations.

The FOCUS SW D4-stream-scenario for generates a concentration of 0.657 µg/l, while the PestSurf simulation reaches 11.8 µg/l. In both simulations, the maximum concentrations are generated by wind drift. The maximum concentrations in PestSurf are reached because a long stretch of stream receives drift simultaneously. 125 m from the upstream end, a concentration of 4.46 µg/l is reached. The water depth at this time is only about 5.2 cm, and the cross section is triangular. There is therefore a factor of 11.5 hidden in the difference in water depth and shape. The maximum concentration reached on the stretch from 500 to 1700 m from the upstream end is 5.02 µg/l.

The macrophyte concentrations were in all cases small compared to the concentration in the water phase.

Sediment concentrations are systematically lower in PestSurf than in FOCUS SW.

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Version 1.0 December 2006, © Danish Environmental Protection Agency