Pesticide dispersion by spraying under tropical conditions |
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Authors: | Tomaz Langenbach Denise Mano Maize M Campos Alessandra LMC Cunha Tácio MP De Campos |
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Institution: | 1. Civil and Environmental Engineering Department, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil;2. Chemistry Department, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil |
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Abstract: | Pesticide air pollution by spraying was evaluated under different temperature, humidity and wind climatic conditions in Brazil. Field experiments were performed with application towards the soil and in guava orchards, where spray dispersion was monitored by adding p-aminobenzoic acid (PABA), a fluorescent substance, as a tracer to the water contained in the spray tanks. Samples were collected with filter membranes (Whatman 180025), and the PABA was extracted from the filters by shaking with water in a Petri dish and measured in a spectrofluorometer. A spray aimed towards the soil with filters positioned on the ground and hung at different heights did not show different upward dispersion as observed when lateral pulverization was conducted. In this case, a tractor with a sprayer moved through a 3 m high and 6 m wide frame with filter membranes mounted at 60 cm intervals. Spray dispersion patterns were modified by guava leaf resistance. No influence of temperature and humidity was observed in this short-lived spraying process. Nevertheless, wind drift can occur during airborne dispersion and is an important pesticide pollution source which requires control. Droplets with PABA powered by assisted spraying upwards returned to the ground by gravity and, therefore, did not constitute a vertical source of atmospheric pollution. |
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Keywords: | Air pollution pesticides spraying pesticide pulverization fluorescence tracer |
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