Risco climático de ocorrência de deriva em aplicações de pesticidas no Brasil

Abstract

The use of pesticides in agriculture has been important to maintain satisfactory agricultural production, aiming to meet the growing global demand for food. Brazil is among the countries with the highest pesticide consumption, due to its large agricultural production and climatic conditions that allow for up to three harvests per year. Despite their importance in agriculture, pesticides can cause damage to the environment and human health, affecting non-target organisms such as beneficial insects, soil organisms, fauna and flora in adjacent areas, as well as contaminate water sources. Spray drift occurrence during pesticide applications has been one of the main causes of environmental contamination caused by pesticides, which can be exacerbated by adverse weather conditions such as wind speed and direction, relative humidity, air temperature, and precipitation. The objective of this study was to estimate and compare the risk of spray drift occurrence in pesticide applications in Brazil based on the meteorological variables that influence it during different times of the day and months of the year, as well as to understand the spatial distribution of these variables in these periods. Meteorological data were obtained from meteorological stations of the National Institute of Meteorology (INMET), from which the risk of spray drift occurrence in each location and the meteorological factors with the greatest influence on the risk composition were estimated. Hours with spray drift occurrence risk were considered those with precipitation occurrence, air temperature above 30 °C, relative humidity below 55%, and wind speed greater than 2.78 m s-1. Boxplot graphs were generated by Brazilian region with monthly and hourly risk values, as well as monthly and hourly maps using the IDW interpolation tool. Considering wind speed <0.83 m s-1 as a risk, a variation of this risk between 16 and 99%, with an average value of 68%, was observed. In the analysis without wind speed <0.83 m s-1 as a risk generator, the Northeast region had the highest average risk (48%), and the North region had the lowest average risk (33%). In the North and Central-West regions, the months of August and September had the highest risk of spray drift occurrence, while in the Northeast region, the months of September and October had the highest risk. In the Southeast region, September had the highest risk, and in the South region, the highest risk occurred from August to December. The elements with the greatest influence on monthly risk occurrence were high air temperature in the North region, low relative humidity in the Northeast, Central-West and Southeast regions, and wind speed greater than 2.78 m s-1 in the South region. The highest risk of drift occurrence was observed between 14:00 and 15:00 hours (UTC-3). In the territorial analysis, considering wind speeds less than 0.83 m s-1 as a risk generator, 90% of the territory presented risk above 70% between 15:00 and 20:00 hours UTC.