To evaluate residues of pesticides that have environmental concern, thirty sampling sites were selected through mainstreams and branches of Keum, Mangyung and Dongjin rivers, and water samples were regularly collected at a monthly intervals, especially biweekly from May to August in 2013. Of the fungicides monitored, hexaconazole, iprobenfos, isoprothiolane and thifluzamide were detected in 11, 137, 85 and 82 samples, respectively, and their average residue concentrations were 0.008 �g/L for hexaconazole, 0.194 �g/L for iprobenfos, 0.103 �g/L for isoprothiolane and 0.044 �g/L for thifluzamide. While other fungicides such as fludioxonil and phthalide were detected with low frequencies and low concentrations. Of the insecticides monitored, carbofuran, diazinon, beta-endosulfan and endosulfan sulfate were detected in 47, 13, 20 and 28 samples, respectively, and their average residue concentrations were 0.194 �g/L for carbofuran, 0.013 �g/L for diazinon, 0.006 �g/L for beta-endosulfan and 0.004 �g/L for endosulfan sulfate. And cypermethrin and dimethoate were detected with concentrations of 0.8 �g/L and 0.3 �g/L in only one sample, respectively. Of the herbicides monitored, alachlor, butachlor, dithiopyr, ethafluralin, mefenacet, metolachlor, oxadiazon, pentoxazone, simetryn and thiobencarb were detected with frequencies of 0.3-29.0% and their residue level of 0.04-9.31 �g/L in positive samples. Among them, average residue levels of butachlor and oxadiazon detected particularly high frequencies were 0.147 �g/L and 0.236 �g/L, respectively. Detection frequencies and residue levels of insecticides and herbicides were the highest in waters sampled in May-Jury. Almost all pesticides detected could be inferred as use for the rice plants but their residue levels were very low compared with standard values.

Monitoring of pesticide residues in rivers in Korea

248th National Meeting (2014)

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