殺菌劑免克寧在土壤中之降解與降解產物的生成對土壤菌相之影響

Abstract

免克寧是已知的內分泌干擾物質，近年研究發現其降解產物2-[[(3,5-dichlorophenyl)-carbamoyl]-oxy]-2methyl-3-butenoic acid (M1)和3’,5’-dichloro-2-hydroxy-2-methylbut-3-enanilide (M2) 與雄性激素受器的親和性較免可寧高。同時，最終降解物3,5-二氯苯胺 (M3) 為二氯苯胺立體異構物中腎毒性最強之化合物。免克寧屬非持久性農藥，隨著降解現象的發生，它的降解物質會存在於土壤或是植物體中。為了得知免克寧及其降解產物 (M1、M2及M3) 在土壤中降解的動態及對土壤微生物族群的影響，本研究利用溶劑萃取法進行土壤中免克寧及降解產物的萃取，再使用高效液相層析法 (HPLC) 及氣相層析儀搭配電子捕獲式偵測器 (GC-ECD) 來進行殘留量的測定。最後藉由變性梯度凝膠電泳 (PCR-DGGE) 來觀測免克寧及降解產物對土壤菌相的影響。免克寧在pH 5之桃園農改場土壤的半生期為12-13天，於pH 7之花蓮農改場土壤的半生期為7-9天。濃度50 mg kg-1免克寧降解試驗結束時 (試驗48天)，未滅菌組免克寧的殘量介於3.14-4.01 mg kg-1，免克寧降解產物M1的濃度為14.60-17.77 mg kg-1，免克寧的降解產物M2的含量於試驗結束時介於0.32-0.91 mg kg-1，M3的累積濃度則為3.27-6.27 mg kg-1。滅菌組免克寧的殘留量為3.25-30.90 mg kg-1，M1累積濃度介於1.35-18.48 mg kg-1，M2的累積量達2.16-8.75 mg kg-1，M3的累積量可達0.75 mg kg-1。研究結果顯示，免克寧的降解由化學水解與微生物降解共同作用，未滅菌處理降解至M3的速率較滅菌處理快，各處理的降解情形於試驗期間停留於中間產物階段 (M1) 較長的時間，M3會隨著時間的增加而逐漸累積。PCR-DGGE的實驗結果亦顯示，免克寧或其降解產物對於土壤菌相的影響在施用中期的影響最大，而其土壤微生物菌相有消長的趨勢。

Vinclozolin has found to have the anti-androgen potential, and its metabolites, M1 and M2, are currently found to have more affinity to androgen receptors than their par-ent chemical, vinclozolin. Also, its final metabolite, 3,5-dichloroaniline, is found for more acute nephrotoxicity than other dichloroaniline stereoisomers. To monitor the de-gradation of vinclozolin and its metabolites production, and to investigate the impact of vinclozolin with its metabolites on soil microbial community, we used DNA extracted kits to collect the soil microbe’s DNA, and used solvent phase extraction to extract vin-clozolin and its metabolites. Then we utilized HPLC-UV and GC-ECD to detect vin-clozolin and metabolites in soil sample. The influences of vinclozolin and its metabolites on soil microbial community were visualized by PCR-DGGE. The half-life time of vinclozolin was 12-13 days in Pu soil and 7-9 days in Wl soil, and vinclozolin was re-sidual for more than 40 days. M1 and M2 produced in treated soils within 3 day, and they increased with time. For 48 days of incubation, M1 were amassed from 14.60 mg kg-1 to 17.77 mg kg-1 in non-sterilized soil, and from 1.35 mg kg-1 to 18.48 mg kg-1 in sterilized soil. The concentrations of Vinclozolin M2 were between 0.32 mg kg-1 and 0.91 mg kg-1 in non-sterolized soil, and between 2.16 mg kg-1 and 8.75 mg kg-1 in steri-lized soil. Additional, the degradated product M3, 3,5-dichloroaniline, could accumu-lated to 6.27 mg kg-1. Finally, the soil pH and soil microbial were the two important factors in vinclozolin degradation and metabolites production. Although vinclozolin were rapid degradated, there were other products appear. The application of vilcolzolin to soil will impact the soil microbial community, and it is important to notice the residual in our environment and to re-evaluate whether the regulation of vinclozolin has been updated.