Adsorption and residues of EPN in the soil of Cheju Island

제주도 토양에서 EPN의 용탈과 잔류

The adsorption and leaching of organophosphorus pesticide, EPN (O-ethyl-O-4 -nitrophenyl phenyl phosphonothioate) were investigated in Namwon soil(black volcanic soil), Aewol soil(very dark brown volcanic soil) and Mureung soil(dark brown nonvolcanic soil) in Cheju Island. The residue of EPN was surveyed on coastal environment of Cheju in Aug. 1996. The organic matter of Namwon soil, Aewol soil and Mureung soil was 19.8, 6.2 and 2.4%, respectively. The cation exchange capacity of Namwon soil, Aewol soil and Mureung soil was 24.8, 13.0 and 9.5 meq/100 g, respectively. The Freundlich constant, k value, was 89.4, 26.9 and 9.25 for Namwon soil, Aewol soil and Mureung soil, respectively. The k value of Namwon soil with very high organic matter content and cation exchange capacity was the highest for Aewol soil and Mureung soil. The Freundlich constant, 1/n, show a high correlation with organic matter content, i.e. it is less than unity for organic matter rich soil of Namwon soil and greater than unity for organic matter poor soil of Mureung soil. The leaching of EPN was slower for Namwon soil with high k values, and faster for Mureung soil with low k values. The results of the study was demonstrated the potential of pollution for EPN have little leached into soil environment. EPN was not detected in seawater and sediment in the coastal environment in Cheju Island. EPN used in the farm on tile Cheju island were not residued in the coastal environment.

제주도 토양에서 EPN(O-ethyl-O-4 -nitrophenyl phenylphosphonothioate) 유기인계 농약의 이동을 예측하기 위해서, 제주도의 흑색 화산회토인 남원토양, 농암갈색 화산회토인 애월토양 및 암갈색 비화산회토인 무릉토양에서 EPN의 흡착과 토양칼럼에서 용탈을 검토하였으며, 또한 연안해수와 저니토에서의 EPN 잔류를 조사하였다. 남원토양, 애월토양, 무릉토양의 유기물함량은 각각 19.8%, 6.2%, 2.4%였고, 양이온 치환용량은 각각 24.8 meq/100g, 13.0 meq/100g, 9.5 meq/100g이었다. Freundlich 상수 k는 남원토양, 애월토양, 무릉토양에서 각각 89.4, 26.9, 9.2로 남원토양>애월토양>무릉토양의 순으로 감소하였다. 즉 유기물 함량 및 양이온 치환용량이 매우 높은 토양인 남원토양에서 흡착능이 높았다. Freundlich 상수 1/n은 유기물 함량이 많은 남원토양에서 0.82로 1보다 낮게 나타났으며, 유기물함량이 적은 무릉토양에서는 1.07로 1보다 높았다. EPN의 토양 중 용탈은 거의 일어나지 않았다. 토성별 용탈 경향은 농약의 흡착능이 큰 남원토양이 가장 침출이 적었고, 흡착능이 작은 무릉토양은 상대적으로 크게 일어났다. 한편 EPN은 도두와 위미에서의 해수와 저니토에서 모두 검출되지 않았다.