The Impact of Pesticides - Academy Publish

A measured volume (1000 mL) of the water was shaken with 100 mL ofdichloromethane after addition of 50 g of NaCl. The organic layer was again shakenand filtered through anhydrous Na 2 SO 4 and the aqueous layer was again shaken andfiltered in the same manner. The combined filtrate was rotary-vacuum evaporatedjust to dryness at 40℃ and the residue was dissolved in 1 mL of hexane.Determination of the pesticides in the hexane solution was performed using SIM byGC-MS. In 2007 and 2009, analyses were performed by the following procedure(Nakamura et al. 2008). A measured volume (500 mL) of water sample was passedthrough a Aqusis PLS-3 column and eluted with 4 mL of dichloromethane afterdrying with air stream at room temperature for 40 min. Detemination of the 10pesticides in the eluate was performed using SIM by GC/MS after evaporation to0.5 mL. Average recoveries (n=3) were 88-108% for the 10 pesticides at a spikedlevel of 0.1 μg/L and quantification limits were 0.01 μg/L for all of the 10pesticides.Results of surveyVariatons in yearly maximum concentrations of the two insecticides (diazinon andfenitrothion) in Yanamune River were compared with those in their shipmentamounts (Fig. 14). Diazinon concentrations showed no tendency to increase ordecrease from 1988 to 1996 but showed low values (0.01 μg/L and ND) in 2007 and2009, respectively. The variations in shipment amounts of diazinon showeddecreasing tendency after 1996 and this tendency was equal to those in theconcentrations after 1996. On the other hand, fenitrothion showed decreasingtendency in both of the concentrations and the shipment amounts from 1990 to2007.Fig. 14 Variations in shipment amounts of two insecticides in Shiga Prefecture andtheir yearly maximum concentrations in Yanamune River waterConcentration (μg/L)10.10.01Diazinon1988198919901991199219931994199519961997199819992000200120022003200420052006200720082009YearConcentrationShipment amountND1086420Shipment amount (t)Concentration (μg/L)Fenitrothion10.10.011988198919901991199219931994199519961997199819992000200120022003200420052006200720082009YearConcentrationShipment amountND3020100Shipment amount (t)AcademyPublish.org - The Impact of Pesticides276