Mitigation of azinphos-methyl in a vegetated stream: Comparison of runoff- and spray-drift

• Published in: Chemosphere (Oxford) 2006, Vol.62 (2), p.204-212
• Main Authors: Dabrowski, J.M., Bennett, E.R., Bollen, A., Schulz, R.
• Format: Article
• Language: English
• Subjects: agricultural runoff; Agronomy. Soil science and plant productions; Applied sciences; Azinphos-methyl; Azinphosmethyl - analysis; Biodegradation, Environmental; Biological and medical sciences; Continental surface waters; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; environmental fate; Exact sciences and technology; Fresh Water - chemistry; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; insecticide residues; macrophytes; Magnoliopsida - growth & development; Mitigation; Natural water pollution; Pollution; pollution control; Pollution, environment geology; Runoff; Soil and water pollution; Soil science; sorption; Spray-drift; streams; Vegetation; Waste Disposal, Fluid - methods; Water Movements; Water Pollutants, Chemical - analysis; water pollution; Water treatment and pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2005.05.021

The effectiveness of aquatic macrophytes in reducing runoff- and spray-drift-induced azinphos-methyl (AZP) input was compared in a vegetated stream. Water, sediment and plant samples were taken at increasing distances from a point of input during a spray-drift event and two runoff (10 and 22 mm/day) events. Peak concentrations of AZP decreased significantly ( R 2 = 0.99; p < 0.0001; n = 5) from 0.24 μg/l to 0.11 μg/l during the 10 mm runoff event. No reduction took place during the 22 mm event. AZP concentrations were reduced by 90% following spray-drift input, with peak concentrations decreasing significantly ( R 2 = 0.93; p = 0.0084; n = 5) from 4.3 μg/l to 1.7 μg/l with increasing distance from the point of input. Plant samples taken after the spray-drift event showed increased AZP concentrations in comparison to before the event indicating sorption of the pesticide to the macrophytes. Although peak concentrations of AZP were as effectively mitigated during the 10 mm runoff event as during the spray-drift event, predictive modelling revealed that maximum concentrations expected during a worst-case scenario 10 mm runoff event (0 days after application) are an order of magnitude lower than what can be expected for a worst-case spray-drift and 22 mm runoff event, suggesting that spray-drift-derived pesticide concentrations are more effectively mitigated than those of runoff.