CONTAMINATION OF ORGANIC PESTICIDES IN SURFACE WATER OF CHATTOGRAM METROPOLITAN AREA AND PHOTOMETRIC EFFECTS IN REMOVING THESE SUBSTANCES

Abstract

Organic pesticides applied to agricultural lands and the wash water of fruits and vegetables have strong capacity to contaminate surface water resources. Regular use of contaminated ground and surface water make the natural attenuation of these pesticides more complex and people are directly affecting through use and consumption of water containing higher level of toxic pesticides. This research aimed to detect the concentration of chlorpyrifos and carbaryl, pesticides belonged to the organophosphate and carbamate pesticide groups respectively, in surface water sources collected from different locations of Chattogram Metropolitan Area and observe photometric effects on their concentration by exposing the water samples to sodium light. Gas Chromatography Mass Spectrometry (GCMS) technique was used to detect and measure the concentration of chlorpyrifos and carbaryl pesticides in the treated water samples. 08 out of 12 water samples contained carbaryl ranging from 61.11 ppb to 216.1 ppb, which are above the WHO guideline value. Only 04 water samples contained carbaryl below the WHO guideline value which is still alarming. Chlorpyrifos was not detected in any of the water samples. Disc polarimeter with 589.44 nm wavelength was used as a source of light to observe whether exposure to specific light intensity has any effect on the concentration of the pesticides. After 10 minutes exposure to the 589.44 nm wavelength light, on an average, 95.35% of the carbaryl contents were removed from every water sample contaminated with carbaryl. The lowest percentage removal of carbaryl from water sample was 87.92% while the highest carbaryl removal percentage from water sample was 98.40%. Specific regulation guidelines must be introduced to limit the use of carbaryl in Bangladesh to assure safe water for people.