Leaching and mobility prediction of butachlor, ethoprophos, iprobenfos, isoprothiolane and procymidone in soils

This study was conducted to investigate the downward mobility of pesticides using soil colunms and to compare the experimental results with predicted values from Convective mobility test model. Five pesticides including ethoprophos, procymidone, iprobenfos, isoprothiolane, and butachlor were subjected to soil column leaching test for three types of cultivation soils. The concentrations of ethoprophos, iprobenfos, procymidone, isoprothiolane and butachlor leached from soil column of 30 cm depth ranged $0.74{\sim}3.61mg/mL,\;0.36{\sim}1.67mg/L,\;0.16{\sim}0.84mg/L,\;0.16{\sim}0.67mg/L$ and lower than 0.15 mg/L, respectively. Elution volume to reach the peak of ethoprophos, iprobenfos, procymidone, isoprothiolane and butachlor in the leachate ranged $2{\sim}4PV,\;3{\sim}10PV,\;5{\sim}13PV,\;4{\sim}14PV\;and\;19{\sim}61PV$, respectively. Convection times predicted by Convective mobility test model at standard conditions were $9{\sim}18$ days for ethoprophos, $17{\sim}35$ days for iprobenfos, $24{\sim}54$ days for isoprothiolane, $21{\sim}65$ days for procymidone and $105{\sim}279$ days for butachlor. Based on these convection times, ethoprophos was classified as mobile or most mobile, isoprothiolane and procymidone as moderately mobile or mobile and butachlor as slightly mobile. On the same conditions, convection times from the model were coincided with those from soil column test in most of the soil-pesticide combinations applied. Therefore, Convective mobility test model could be applied to predict convection times of pesticides.

Butachlor, ethoprophos, iprobenfos, isoprothiolane 및 procymidone의 토양 중 용탈과 이동성 예측

토주용탈실험으로 농약별 이동 양상을 파악하고, 흡착계수와 토양관련 매개변수를 이용하여 대류 이동성 모형(Convective mobility test model)으로 예측한 용탈 속도와 비교 평가하였다. 토양살충제 ethoprophos, 원예용 살균제 procymidone, 도열병약 iprobenfos와 isoprothiolane 및 수도용 제초제 butachlor를 대상농약으로 선정하고 토지이용 형태를 기준으로 논, 밭 및 산림토양으로 구분한 3종의 토양에 대하여 토주용탈실험을 수행하였다. 각 농약을 $50{\mu}g/cm^2$ 수준으로 토주 상단에 처리하였을 때 토심 30 cm 이동 후 용탈되는 농약별 peak 농도는 ethoprophos $0.74{\sim}3.61mg/mL$, iprobenfos $0.35{\sim}1.67mg/L$, procymidone $0.16{\sim}0.84mg/L$, isoprothiolane $0.16{\sim}0.67mg/L$, butachlor 0.15 mg/L이하 수준이었고, peak 농도 출현까지 소요된 용탈수량은 ethoprophos $2{\sim}4$ pore volume (PV), iprobenfos $3{\sim}10PV$, procymidone $5{\sim}13PV$, isoprothiolane $4{\sim}14PV$, butachlor $19{\sim}61PV$ 수준이었다. 대류 이동성 모형에 의한 예측 결과, 이동소요시간은 표준조건에서 ethoprophos $9{\sim}18$일, iprobenfos $17{\sim}35$일, isoprothiolane $24{\sim}54$일, procymidone $21{\sim}65$일 및 butachlor $105{\sim}279$일로 나타나 대류 이동성 모형 분류에 따르면 ethoprophos는 mobile${\sim}$most mobile, iprobenfos, isoprothiolane 및 procymidone은 moderately mobile${\sim}$mobile 그리고 butachlor는 slightly mobile 등급에 속하는 것으로 나타났다. 토주용탈실험과 동일한 조건으로 대류 이동성 모형에 의하여 이동소요시간을 예측한 결과는 대부분의 토양-농약 조합에서 잘 일치하여 이동소요시간의 예측에 대류 이동성 모형을 이용하는 것이 가능할 것으로 생각된다.