Effectiveness of activated soil containing directly enriched atrazine-degrading soil microorganisms as an inoculant to bioaugment degradation of atrazine in soils was investigated. A Wooster silt loam (Typic Fragiudalf) was spiked with atrazine at a rate of 4 mg/kg soil three successive times to create activated soil. Atrazine degradation was significantly enhanced (p < 0.05) after the first treatment. After the second treatment, there was an increase in the number, based on MPN, of microorganisms utilizing atrazine as a C- and N-source by 3 logs and 1 log of magnitude, respectively. Inoculation of typical agricultural soils collected from Ohio with activated soil at a rate as low as 0.5% reduced the extractable atrazine remaining in soils to the level below 2% of that initially recovered (initially added at a rate of 4 mg/kg soil) after 4 days. Inoculation at a higher rate was required to achieve the same result in soils with non-typical properties (pH of 4.5 or organic matter of 43% w/w). Activated soil was stable, in terms of atrazine degradation activity, at least up to 6 months when it was kept at low temperature (< $10^{\circ}C$) and moistened (water content above 15%). The results of this study indicate that microorganisms capable of degrading atrazine are relatively easily enriched in soil to create activated soil. Use of activated soil can be a practical option for bioremediation of contaminated soils.

토양내 atrazine 분해촉진을 위한 생물적 증진제로서의 토양내에서 직접증식된 Atrazine 분해 미생물을 함유하는 활성토의 효용성을 조사하였다. Atrazine 분해미생물을 증식시키기 위하여 Wooster silt loam을 4 mg/kg 농도의 atrazine으로 3회 연속처리하며 atrazine 분해 미생물 수와 atrazine 분해속도를 관찰한 결과, 1회 처리 후 atrazine 분해속도가 현저하게 증가하였고, 2회 처리 후 atrazine을 탄소원과 질소원으로 이용하는 미생물의 수가 각각 103, 101배 증가하였다. 증식된 미생물을 함유하는 이 활성토를 atrazine에 오염(초기농도4 mg/kg)된 Ohio의 전형적인 농지 토양에 0.5%비율로 접종하였을 때, 토양내atrazine 농도가 4일만에 초기농도의 2% 이하로 감소하였다. 비전형적인 토양(pH 4.5 또는 유기물함량 43%)에서 같은 효과를 얻기 위해서는 더 높은 비율의 접종이 필요하였다. 활성토는 저온($10^{\circ}C$ 이하) 습윤(수분함량 15%)한 상태에서 최소한 6개월간 안정하였다. 본 연구결과는 atrazine 분해미생물이 토양내에서 비교적 쉽게 증식되며, 이를 함유하는 활성토가 토양내에서의 atrazine 분해 촉진을 위한 접종제로 유용하게 이용될 수 있음을 보여준다.

Keywords: Atrazine;Bioaugmentation;Bioremediation;Activated soil;Pesticide;

Keywords: 생물학적 복원;활성토;농약;