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Spray Deposition of Two Insecticides into Surface Waters in a South African Orchard Area

Spray Deposition of Two Insecticides into Surface Waters in a South African Orchard Area Drift from pesticide spray application can result in contamination of nontarget environments such as surface waters. Azinphos‐methyl (AZI) and endosulfan (END) deposition in containers of water was studied in fruit orchards in the Western Cape, South Africa. Additionally, attention was given to the contamination in farm streams, as well as to the resulting contamination of the subsequent main channel (Lourens River) approx. 2.5 km downstream of the tributary stream inlets. Spray deposit decreased with increasing distance downwind and ranged from 4.7 mg m−2 within the target area to 0.2 mg m−2 at 15 m downwind (AZI). Measured in‐stream concentrations of both pesticides compared well with theoretical values calculated from deposition data for the respective distances. Furthermore, they were in the range of values predicted by an exposure assessment based on 95th‐percentile values for basic drift deposition (German Federal Biological Research Centre for Agriculture and Forestry [BBA] and USEPA). Pesticide deposition in the tributaries was followed by a measurable increase of contamination in the Lourens River. Mortality of midges (Chironomus spp.) exposed for 24 h to samples obtained from the AZI trials decreased with decreasing concentrations (estimated LC50 from field samples = 10 μg L−1 AZI; lethal distance: LD50 = 13 m). Mortality in the tributary samples averaged 11% (0.5–1.7 μg L−1 AZI), while no mortality was discernible in the Lourens River samples (0.041 μg L−1). The sublethal endpoint failure to form tubes from the glass beads provided was significantly increased at all sites in comparison with the control (analysis of variance [ANOVA], Fisher's protected least significant difference [PLSD], p < 0.01). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Environmental Quality Wiley

Spray Deposition of Two Insecticides into Surface Waters in a South African Orchard Area

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References (34)

Publisher
Wiley
Copyright
© American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America
ISSN
0047-2425
eISSN
1537-2537
DOI
10.2134/jeq2001.303814x
Publisher site
See Article on Publisher Site

Abstract

Drift from pesticide spray application can result in contamination of nontarget environments such as surface waters. Azinphos‐methyl (AZI) and endosulfan (END) deposition in containers of water was studied in fruit orchards in the Western Cape, South Africa. Additionally, attention was given to the contamination in farm streams, as well as to the resulting contamination of the subsequent main channel (Lourens River) approx. 2.5 km downstream of the tributary stream inlets. Spray deposit decreased with increasing distance downwind and ranged from 4.7 mg m−2 within the target area to 0.2 mg m−2 at 15 m downwind (AZI). Measured in‐stream concentrations of both pesticides compared well with theoretical values calculated from deposition data for the respective distances. Furthermore, they were in the range of values predicted by an exposure assessment based on 95th‐percentile values for basic drift deposition (German Federal Biological Research Centre for Agriculture and Forestry [BBA] and USEPA). Pesticide deposition in the tributaries was followed by a measurable increase of contamination in the Lourens River. Mortality of midges (Chironomus spp.) exposed for 24 h to samples obtained from the AZI trials decreased with decreasing concentrations (estimated LC50 from field samples = 10 μg L−1 AZI; lethal distance: LD50 = 13 m). Mortality in the tributary samples averaged 11% (0.5–1.7 μg L−1 AZI), while no mortality was discernible in the Lourens River samples (0.041 μg L−1). The sublethal endpoint failure to form tubes from the glass beads provided was significantly increased at all sites in comparison with the control (analysis of variance [ANOVA], Fisher's protected least significant difference [PLSD], p < 0.01).

Journal

Journal of Environmental Quality – Wiley

Published: May 1, 2001

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