Backgrounds and Objectives: Water contamination by pesticides is considered as an environmentalproblem today. In terms of agricultural development and diversity of plant pests, the use of pesticides has been increasing. Hamedan province has a suitable agricultural condition, it has enjoyed significant development in this respect. Among all the cities of Hamedan province, Hamedan city has the highest rank in tiller crops. Therefore, yearly use of pesticides is increasing in this area; which could be a serious threat to water resources of the city. The aim of this survey was determinaton of Organophosphorous and Carbamat pesticides residue in drinking water resources of Hamadan in 2007.
Materials and Methods: In this survey, 126 water samples were collected from 7 drinking water resources of Hamedan during 12 consecutive months in 2007. for determination of these pesticides,two methods (solid- phase extraction and Liquid-Liquid extraction) were adopted .and samples were analyzed by means of HPLC and GC/MS applying standard methods.
Results: Final results showed that the most concentration of Chlorpyrifos and Carbaryl pesticides were found to be about 3.85 ppb (part per billion) and 1.8 ppb in spring and June respectively; the maximum concentration of Diazinon was about 36.5ppb in October (autumn).The minimum concentration of the three pesticides was detected in winter. According to the statistical test Two - Way ANOWA there were significant differences among pesticides concentrations in the water samples in different seasons (p<0.05) . However, there wasn't a significant difference in pesticides concentrations in surface and ground water samples(p>0.05).
Conclusion: Different studies have shown that pesticides residue concentration in water samples have a relationship with the amount of pesticides used in an area, physical and chemical refractory properties of pesticides; and environmental conditions. Thus, using resistant pollutants such as pesticides will be a serious threat to health of water consumers if they are not properly controlled.