title: Toxic effects of ionic liquid 1-octyl-3-methylimidazolium tetrafluoroborate on soil enzyme activity and soil microbial community diversity.
abstract: Ionic liquids (ILs) were considered as "green" solvents and have been used widely because of their excellent properties. But ILs are not as "green" as has been suggested, and the toxic effects of ILs on organisms have been shown in recent years. In the present study, the toxic effects of the IL 1-octyl-3-methylimidazolium tetrafluoroborate ([Omim]BF4) on soil enzyme activity and soil microbial communities at three different concentrations (1.0, 5.0 and 10.0mg/kg) and a control treatment over 40 days of incubation time (sampled on days 10, 20, 30 and 40) were examined under laboratory conditions. The concentrations of [Omim]BF4in soils were detected by high performance liquid chromatography (HPLC) and the results indicated that [Omim]BF4were maintained stable in the soil during the exposure period. However, the enzyme activity results showed that urease activity was stimulated on day 20 and then decreased after 30 days of incubation. The activity of β-glucosidase was stimulated after 20 days of incubation in both treatment groups. Moreover, both dehydrogenase and acid phosphatase were inhibited at a high level (10.0mg/kg) only on day 20. The analysis of terminal restriction fragment length polymorphism (T-RFLP) revealed that the soil microbial community structures were altered by [Omim]BF4and that the soil microbial diversity and evenness of high levels (5.0mg/kg and 10.0mg/kg) treatments were decreased. Moreover, the dominant structure of the microbial communities was not changed by [Omim]BF4. Furthermore, the abundance of the ammonia monooxygenase (amoA) genes of both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) was examined using real time polymerase chain reaction (RT-PCR). The results revealed that the copy numbers of the amoA-gene were decreased by [Omim]BF4with the 5.0 and 10.0mg/kg treatments. Based on the experiment, we concluded that high levels (5.0 and 10.0mg/kg) of [Omim]BF4could have significantly toxic effects on soil enzyme activities and the diversity of the microbial communities.
authors.affiliation: Key Laboratory of Agriculture Environment in Universities of Shandong, College of Resources and Environment, Shandong Agricultural University, Taian 271018, PR China.
authors.forename: Xi
authors.initials: X
authors.lastname: Sun
authors.affiliation: Key Laboratory of Agriculture Environment in Universities of Shandong, College of Resources and Environment, Shandong Agricultural University, Taian 271018, PR China. Electronic address: lushzhu@vip.163.com.
authors.forename: Lusheng
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Agriculture Environment in Universities of Shandong, College of Resources and Environment, Shandong Agricultural University, Taian 271018, PR China.
authors.forename: Jinhua
authors.initials: J
authors.lastname: Wang
authors.affiliation: Key Laboratory of Agriculture Environment in Universities of Shandong, College of Resources and Environment, Shandong Agricultural University, Taian 271018, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China. Electronic address: shuying5211@126.com.
authors.forename: Benying
authors.initials: B
authors.lastname: Su
authors.affiliation: Key Laboratory of Agriculture Environment in Universities of Shandong, College of Resources and Environment, Shandong Agricultural University, Taian 271018, PR China.
authors.forename: Tong
authors.initials: T
authors.lastname: Liu
authors.affiliation: Key Laboratory of Agriculture Environment in Universities of Shandong, College of Resources and Environment, Shandong Agricultural University, Taian 271018, PR China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Agriculture Environment in Universities of Shandong, College of Resources and Environment, Shandong Agricultural University, Taian 271018, PR China.
authors.forename: Chong
authors.initials: C
authors.lastname: Gao
authors.affiliation: Key Laboratory of Agriculture Environment in Universities of Shandong, College of Resources and Environment, Shandong Agricultural University, Taian 271018, PR China.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Shao
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000641:Ammonia / Q000378:metabolism; D001105:Archaea / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D001419:Bacteria / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D018628:Gene Dosage / Q000187:drug effects; D007093:Imidazoles / Q000633:toxicity*; D052578:Ionic Liquids / Q000633:toxicity*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D012150:Polymorphism, Restriction Fragment Length; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D014510:Urease / Q000378:metabolism; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: C446740:1-octyl-3-methylimidazolium hexafluorophosphate; D007093:Imidazoles; D052578:Ionic Liquids; D012987:Soil; D000641:Ammonia; D010088:Oxidoreductases; C045582:ammonia monooxygenase; D000135:Acid Phosphatase; D001617:beta-Glucosidase; D014510:Urease
keywords: Ammonia-oxidizing archaea; Ammonia-oxidizing bacteria; HPLC; Ionic liquids; RT-PCR; T-RFLP