Investigation on downwind short-range transport of pesticides after application in agricultural crops
Introduction
During and after spraying of plant protection products, the compounds applied to crops or soil can partly move by air to non-target areas in the lee where they can stress fauna, flora and humans. This exposure is mainly the result of wind-induced drift of the sprayed droplet cloud at the time of application and dispersion of the pesticide vapour released due to volatilisation from the treated crop or soil after completion of the application (van den Berg et al., 1999).
Spray drift has been thoroughly studied over years and is now comprehensively considered in risk assessment as a relevant path of entry. However, there are only few experimental data at present on exposure caused by short-range transport originating from pesticide volatilisation, such as by Ross et al. (1990), Klöppel and Kördel (1997), Roach et al. (1997), Kördel and Klöppel (1998), Hänel (2000) and Epple et al. (2002), which point to the potential relevance of these entries. The authors of this article, too, conducted studies on air pollution next to treated areas at the same field plot already in 1998 and 1999 (Siebers et al., 1999; Wittich and Siebers, 2002). Meteorological aspects and volatilisation rates were described in detail. Based solely on model calculations for the local scale up to a distance of 2 km, de Jong et al., 1995, raised concern that deposition which is mainly caused by volatilisation could alone exceed effect concentrations in the close vicinity to the treated field.
Results of those studies indicated that short-range transport of volatilised pesticides is relevant, too, at least under certain circumstances and in particular with volatile compounds ( Pa at 20 °C) and semi-volatile compounds (vapour pressure 10−6–5×10−3 Pa at 20 °C) (Binner et al., 2000). Consequently, this path of entry must be also considered in certain cases in the risk assessment under Directive 91/414/EEC of the European Union for both bystanders and the environment.
Based on the studies mentioned the German authorities responsible for pesticide registration are developing an evaluation concept including short-range transport resulting from pesticide volatilisation (Gottschild and Nolting, 2002; Winkler et al., 2002). The aim of this paper is to support the evaluation concept by investigating the relevance of deposition caused by volatilised pesticides near treated crops and by giving a detailed description of a study design which can be used to compare predictions of the evaluation concept with experimental data. Moreover, this contribution likes to facilitate the discussion of the German approach regarding the assessment scheme for short-range transport. Therefore, concentrations of selected active substances were determined in air and surface water nearby treated fields at different distances and under different weather conditions to characterise the short-range transport of pesticides. The three insecticides, lindane, parathion and pirimicarb were chosen for the investigations due to their physical–chemical properties (see Table 1) and their volatility.
Section snippets
Site and application
The trials took place on the 16th and 17th May 2000 (trial A) and 16th and 17th June 2000 (trial B) on a site of the BBA’s Experimental Field Station on flat farmland about 3 km south-east of Braunschweig (geographical longitude 11°08 E, latitude 52°58 N). Soil type was sandy loam. Target plots grown with winter barley had a size of 96 m (east/west)×52 m (north/south) in trial A, or 100 m (north/south)×48 m (east/west) in trial B. Surrounding plots were grown with winter barley, winter wheat
Results
The first measurements were carried out after application on the 16th May 2000 (trial A). The weather was fair so that the air temperatures measured at a height of 2.8 m (1.9 m above the top of the barley crop) showed the typical diurnal wave with maximum–minimum values of 28.1 °C in the afternoon and 11.7 °C in the night and an arithmetic average of 21.1 °C. The wind speed was low and ranged from about 0.4 m/s (especially in the morning at the time of pesticide application, in the evening and
Discussion
In the trials described, total pesticide concentrations in surface waters due to spray drift and volatilisation were determined. For measurement of entry by volatilisation, model water containers were covered during treatment to preclude any contamination by spray drift.
Test results confirmed the assumption that volatilisation and ensuing deposition on neighbouring non-target areas should be considered as a relevant way of entry, at least under certain circumstances, for the more volatile
Conclusions
The measurements prove the importance of transport of active substance via volatilisation to non-target areas adjacent to the treatment area and confirm conclusions drawn by other authors, e.g. Kördel and Klöppel, 1998, and Epple et al., 2002, that this path of entry should be also taken into account. Air concentration and deposition of volatilised portions are the potential endpoints for further consideration. Data on air concentration nearby treated fields is important e.g. for the validation
Acknowledgements
The authors express their gratitude to Mrs. Alice Antonius, Mrs. Ester Bock, Mr. Ralf Fischer, Mr. Klaus Goldmann, Mrs. Marianne Grabau, Dr. Ralf Hänel, Mrs. Elke Leibold, Mrs. Kerstin Rogge and especially Mrs. Nuray Demirbas for their help in sampling and/or laboratory analysis throughout this project.
We would also like to thank the employees of the Experimental Field Station Sickte for crop cultivation and spraying the crops and the staff of the German Weather Service for their support.
References (25)
- et al.
Possible side effects of airborne pesticides on fungi and vascular plants in The Netherlands
Ecotoxicology and Environmental Safety
(1995) - et al.
Input of pesticides by atmospheric deposition
Geoderma
(2002) - et al.
Pesticide volatilisation and exposure of terrestrial ecosystems
Chemosphere
(1997) - Anonymous, 2000. Wirkstoffe in Pflanzenschutz- und Schädlingsbekämpfungsmitteln. Physikalisch––chemische und...
Bekanntmachung über die Abtrifteckwerte, die bei der Prüfung und Zulassung von Pflanzenschutzmitteln herangezogen werden
Bundesanzeiger
(2000)- et al.
Der Prüfbereich Luft––Aktueller Stand eines neuen Bewertungskonzepts
Mittl. Biol. Bundesanst. Land-Forstwirtschaft
(2000) - EPPO, 2001. Environmental risk assessment scheme for plant protection products, Chapter 3: Air, European and...
- European Commission, 2000. Guidance document on residue analytical methods. SANCO/825/00/rev. 6, 20.06.00 (2000). This...
- et al.
Bewertungskonzept zum Nahtransport von Pflanzenschutzmitteln über den Luftpfad. 16. Hinweis zum Zulassungsverfahren für Pflanzenschutzmittel und Anwendungstechnik––Z16
Nachrichtenbl. Deut. Pflanzenschutzd.
(2002) - Hänel, R., 2000. Abschlussbericht FC 1799, Validierung der Abdrifteckwerte mit häufig eingesetzten...
Behavior assessment model for trace organics in soil: II. Chemical classification and parameter sensitivity
J. Environ. Quality
Cited by (45)
Measured air concentrations of pesticides for the estimation of exposure to vapour in European risk assessments
2022, Regulatory Toxicology and PharmacologyCitation Excerpt :Therefore, actual VPs under field conditions may vary even during a single sampling time, but this is not normally determined (EU 2008). Previously, Siebers et al. (2003) suggested to explore the potential impact of VPs, application rates, size of treated area, treated crop type, and effect of formulation type. All these aspects were explored with the current dataset.
Review of air concentrations of pesticides for estimating exposure to vapour in European risk assessments
2022, Regulatory Toxicology and PharmacologyCitation Excerpt :This section reviews the history and data behind the current default air concentration values in the EFSA (2014a) used for inhalation exposure estimation. It will become evident that the underlying studies, Siebers et al. (2003) and California EPA (1998), and subsequent guidance interpretation are incongruent with exposure assumptions according to EFSA (2014a). This illustrates that inhalation exposure estimation would benefit from a revised approach or database.
Pesticides in doormat and floor dust from homes close to treated fields: Spatio-temporal variance and determinants of occurrence and concentrations
2022, Environmental PollutionCitation Excerpt :For this, we selected some homes located very close to the fields (<50 m) (N = 16), some more further away (50 m–150 m) (N = 14) and some located between 150 m and 250 m (N = 11). These buffers are based on previous research done on pesticide concentrations at different distances downwind (Siebers et al., 2003; Figueiredo et al., 2021b) and ensured that homes were located both up and down-wind of the application (all cardinal directions). All controls were included in the sample analyses.
Spatio-temporal variation of outdoor and indoor pesticide air concentrations in homes near agricultural fields
2021, Atmospheric EnvironmentCitation Excerpt :Here, we grouped distance by our a-priori defined distance categories (<50 m; 50–150 m; 150–250 m; >250 m; controls). This grouping was based on previous research done on drift effect on air concentrations downwind at different distances from agricultural crops (e.g. Table 5, Siebers et al., 2003). A trend line was added to the graphs using loess regression based on polynomial function.