Impacto do uso de domissanitários no combate a pragas urbanas: estudo de caso em manguezais da Região Metropolitana de Fortaleza - CE

Abstract

Pesticides are used mostly in agriculture in rural areas, but are also used in urban pest control, in public health campaigns, in households and veterinary products. However, these uses are an important source of contamination of water resources from urban centers. The study of the dynamics of pesticides in aquatic environments is essential for development of plans for remediation of potential impacts to humans, biota and the environment. Organic contaminants tend to be retained in estuaries due to its physicochemical characteristics (high values of Kow, Koc, vapor pressure and Henry constant, low solubility in water) and environmental conditions (pH, salinity, suspended particulate matter , temperature). Among them stand out fractions of organic matter, such as carbon black, humic and fulvic acids, lipid content. This study aimed to estimate the contamination of pesticide use and household pest control in urban regions estuarine tidal rivers and Coco Ceará located in the metropolitan area of Fortaleza, Ceará, Brazil. Samples of surface sediments were taken to the Laboratory of Organic Contaminants Analysis (LABOMAR / UFC), which were made granulometric analysis (dry and wet sieving and pipetting), determination of organic matter content by the method of Walkley-Balck modified extraction and quantification of pesticides by gas chromatography coupled to mass spectrometry. The collection points were classified as to the size of the grains, such as sand and sand mudflat. The concentration of organic matter ranged from 0.47 to 9.74%. Of the five analyzed pesticides (bendiocarb, piperonyl butoxide, diflubenzuron, malathion and cypermethrin), only malathion and cypermethrin were detected and quantified. The concentrations of malathion ranged from 0.08 to 0.85 ng.g-1, and cypermethrin from 6.58 to 134.45 ng.g-1. The points located in estuarine areas had the highest concentrations, which corroborated the highest levels of organic matter. For the correlation of data was used the statistical technique of principal component analysis to correlate deposition of cypermethrin and malathion with the fine fraction (silt and clay), more significant for the latter. The chromatographic method was efficient in the detection and quantification of pesticide cypermethrin and malathion. In the evaluation of the factors governing the transport of pesticides and their correlation with the deposition, it was found that most of the pesticides studied are bound to organic matter and silt-clay, both in the river and in the estuary.