A total of 48 water samples and 24 sediment samples were collected at four sampling stations along the wetland during four seasons from 2009 to 2010 and analyzed by gas chromatograph-electron capture detector (GC-ECD). In water the total concentration of OCPs was 0.33, 0.01, 0.1 and 0.07 mg/L in summer, autumn, winter and spring, respectively. The most frequent OCP compounds detected were endrin and chlordane (0.08 and 0.07 mg/L), heaxachlorobenzene and chlordane (0.06, 0.02 mg/L), and chlordane (0.07 mg/L) in summer, winter and spring, respectively. The maximum concentration of ΣOCPs was found in samples collected from station 1 in summer (0.26 mg/L). In sediments the total concentrations of OCPs were 15.84 and 2.62 mg/g-dry weight (dw) in summer and winter, respectively. Chlordane was the most frequently found OCP compound, followed by lindane, 9.92 and 2.47 mg/g-dry weight (dw), respectively, in summer. While, lindane (2.52 mg/g-dw) and endosulfan I (0.1 mg/g-dw) were the highest OCP compounds detected in winter. The results obtained in this study show that there still exist a variety of organochlorine pesticide residues in the water and sediments from the Amir-kalaye wetland in Iran.
Suitable conditions bring about high population of pests or diseases in green-houses and therefore, frequent applications of pesticides occur in this production system which causes public anxiety about pesticide residue in green-house grown crops such as tomato. The present report is the result of an investigation performed on pesticide residue level measurements in green-house grown tomato in Hamadan province. In this study, 43 tomato samples were taken from the green-houses across the province and the residue levels of nine pesticides in each sample were measured. The results indicated that 95.4% of the samples were completely free of all measured insecticides. In 4.6% of the samples the residue of Chlorpyrifos was detected of which the residue level of only one sample (2.3%) was higher than the Maximum residue limit (MRL) for this pesticide in tomato (MRL = 0.1 ppm).
Designing a fast, cheap and easy method which enables detection of the pesticide residue levels on-site is very important. In the present research, a sensitive nanobiosensor has been designed based on gold colloidal nanoparticles that could detect organophosphates and carbamates. It was synthesized using gold plasmonic nanoparticles by chemical growth method on grain particles. This nanobiosensor was optimized in the presence of different concentrations and volumes of aptamer, salt, etc. To detect pesticides by this nanobiosensor Trichlorfon and diazinon (OP) and Carbofuran and pirimicarb (Carb) were used. By interaction of the pesticides with the nanobiosensor, the appearance and color of the nanobiosensor changed markedly, which was visible to the naked eye. The results show, the sensitivity of this nanobiosensor is the lowest to diazinon and the highest to Carbofuran over the time. It seems that in the presence of Trichlorfon, the nanobiosensor designed in the beginning shows significant morphological changes in the nanostructures. The time required for incubation of samples of pesticide and nanobiosensor is determined to be about 10–15 minutes. Another interesting potential of colorimetric nanobiosensor is based on the extreme sensitivity of surface plasmon resonance of gold nanostructures to the surrounding media, which can be functionalized with specific biomolecules for specific detection. Therefore, there is a good potential to replace this new method with conventional methods.
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