Bing Li

Effect of 1-methyl-3-hexylimidazolium bromide on zebrafish (Danio rerio)

Room-temperature ionic liquids, generally referred to ionic liquids (ILs), are green solvents. Antioxidant responses and DNA damage in zebrafish livers exposed to 1-methyl-3-hexylimidazolium bromide ([C6mim]Br) were evaluated at various doses (5-40xa0mg/L) for a 28-day IL-exposure. A significant decrease of superoxide dismutase (SOD) activity was exhibited, and catalase (CAT) was inhibited at the highest dose (40xa0mg/L). Reactive oxygen species (ROS) levels were significantly promoted at most exposure interval times except for the dose of 5xa0mg/L on day 21 in male and days 21 and 28 in female. Malonaldehyde (MDA) contents remarkable increased exposed to [C6mim]Br. Besides, a notable increase was exhibited, which indicated an inducement of DNA damage with respect to control groups. Thus, we believed that [C6mim]Br causes oxidative stress and DNA damage in zebrafish. Gender differences were insignificant in almost all the tested biomarkers, thus, male and female zebrafish could be mixed at a ratio of 1:1 in the future evaluation. The present study may also provide basic toxicology information for IL evaluation to aquatic organisms.

Toxic effect of [Omim]BF 4 and [Omim]Br on antioxidant stress and oxidative damage in earthworms ( Eisenia fetida )

In this paper, model soil organism, earthworms (Eisenia fetida), were selected to examine the chronic toxic effect of two different ionic liquids (ILs) [Omim]BF4 and [Omim]Br. Earthworms were put into different ILs concentrations (0, 5, 10, 20, 40u202fmg/kg) in artificial soil and random selected on days 7, 14, 21 and 28. Reactive oxygen species (ROS), antioxidant enzymes and detoxifying enzyme glutathione-S-transferase (GST) were researched for determination of antioxidant stress. Malondialdehyde (MDA) and olive tail moment (OTM) were researched to determine the oxidative damage. Both the pollutants had the same effect on earthworms: ILs led to accumulation of ROS, and then antioxidant enzymes and detoxification enzyme all changed to eliminate the effects of ROS, and the above process led to lipid peroxidation and DNA damage in earthworms. This paper shows that [Omim]BF4 and [Omim]Br both caused toxicity to earthworms and had the similar toxicity levels.

Exposed zebrafish ( Danio rerio ) to imidazolium-based ionic liquids with different anions and alkyl-chain lengths

Ionic liquids (ILs) were considered new green solvents in consideration of the low volatility. Since their inception, ionic liquids (ILs) have attracted widespread attention. However, ILs were not safe enough as what we thought. The toxicity of 1-ethyl-3-methylimidazolium ILs ([C2mim]R, Ru202f=u202fCl-, Br-, BF4-) and 1-alkyl-3-methylimidazolium bromine ([Cnmim]Br, nu202f=u202f2, 4, 8, 10, 12) using 50% lethal concentration (LC50) were studied in the present study to enrich the toxicological information. Besides the LC50 values, the sensitivity test using potassium dichromate (K2Cr2O7) and residue determinations of the tested ILs were also performed. The sensitivity and dynamic changes of IL doses both catered for the stipulation that declared the accuracy of the toxicological test results, which illustrated that the alkyl-chain lengths contributed more than anions to the toxicity of the ILs described above to zebrafish. Additionally, the present study also enriched the toxicological information on imidazolium-based ILs to aquatic systems.

Evaluating subchronic toxicity of fluoxastrobin using earthworms (Eisenia fetida)

Potential toxicity to soil organisms by fluoxastrobin, a new strobilurin-type fungicide has drawn increasing attention. Thus, the present study investigated the subchronic toxicity induced by exposure to several concentrations (0, 0.1, 1.0, and 2.5u202fmgu202fkg-1) of fluoxastrobin to earthworms on days 7, 14, 21, and 28. Biochemical indicators (e.g., reactive oxygen species (ROS) content, activities of antioxidase and detoxifying enzymes (superoxide dismutase, catalase, and glutathione S-transferase), lipid peroxidation (malonaldehyde) and degree of DNA damage) were measured. No earthworm deaths were observed during the entire experimental period. For ROS and malonaldehyde, the bioassay values of the three doses reached a maximum on day 21 and then decreased. For superoxide dismutase and glutathione S-transferase, the values increased with the exposure doses of 0.1 and 1.0u202fmgu202fkg-1 and then decreased. In contrast, the values for catalase were lower on days 7, 14, and 28 and greater on day 21 compared to those of the controls. In addition, the comet assay was more sensitive than other biomarkers, and the degree of DNA damage was dose and time -dependent.

Evaluation of acetamiprid-induced genotoxic and oxidative responses in Eisenia fetida

As a novel neonicotinoids insecticide, acetamiprid has been widely used worldwide. In this study, a laboratory test was conducted to expose earthworms (Eisenia fetida) to artificial soil spiked with various concentrations of acetamiprid (0, 0.05, 0.10, 0.25 and 0.50u202fmg/kg of soil) respectively after 7, 14, 21 and 28 d. Reactive oxygen species (ROS) generation, antioxidant enzymes activity including superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferases (GST), malondialdehyde (MDA) content, and DNA damage were determined in earthworms. The ROS level increased in varying degrees at most exposure concentrations. The SOD activity was not significantly affected. The CAT activity was increased in the beginning, then gradually suppressed and resumed to the control level at the end, with the maximum change (171%) occurred at 14 d for 0.05u202fmg/kg. The GST activity was induced at 7 d, and then inhibited, with the maximum change (67.6%) occurred at 14 d for 0.50u202fmg/kg. The MDA content had a tendency that increasing at the first and decreasing at the end. The olive tail moment (OTM) in comet assay reflected a dose-dependent relationship, and DNA damage initially increased and then decreased over time. The results suggest that the sub-chronic exposure of acetamiprid can cause oxidative stress and DNA damage of earthworm and change the activity of the anti-oxidant enzyme. In addition, ROS content and DNA damage can be good indicators for assessing environmental risks of acetamiprid in earthworms.

Toxicity of 1-alkyl-3-methyl imidazolium nitrate ionic liquids to earthworms: The effects of carbon chains of different lengths

Ionic liquids (ILs), which are alternatives to traditional organic solvents, have the potential to enter soil and cause negative effects on the soil micro-environment, especially soil organisms. The objective of this study was to determine the alkyl chain effect and cut-off effect mechanisms underlying the toxicity of ILs. The assessment for subchronic toxicity toward earthworms (Eisenia fetida) by five common imidazole nitrate ILs ([Cnmim]NO3 (nu202f=u202f4, 6, 8, 10, and 12)) was conducted on day 28 after exposure to five concentrations (0, 5, 10, 20, and 40u202fmgu202fkg-1) of ILs. Earthworms showed oxidative stress and oxidative damage, and both alkyl chain effect and cut-off effect (occurred in C10) were observed. In addition, the toxicity of ILs increased with the increase in concentration. Analysis of imidazolium ILs in artificial soil at the end of the experiment indicated that these selected ILs remained relatively stable, with a rate of change of less than 7.39%. The present study provides theoretical support for decisions regarding IL use and helps to establish a friendly IL structure database.

Evaluating toxicity of 1-octyl-3-methylimidazolium hexafluorophosphate to microorganisms in soil

Ionic liquids (ILs) were widely applied because of their excellent properties. The present investigation studied the toxicity of the IL 1-octyl-3-methylimidazolium hexafluorophosphate ([Omim]PF6) to the soil microbial population and community diversity with dose (1.0, 2.0, 4.0, 6.0, and 8.0u202fmgu202fkg-1) and exposure time (7, 10, and 13u202fd). The results show the IL was stable during the entire experimental period. The Biolog-ECO plate results indicated that the average well color development (AWCD) in the 6.0 and 8.0u202fmgu202fkg-1 treatments was lower than these in the other treatments. The diversity indices of the Biolog analysis were significantly reduced. The abundance of the ammonia-oxidizing archaea (AOA-) and the ammonia-oxidizing bacteria (AOB-) ammonia monooxygenase (amoA) genes was measured by the real-time polymerase chain reaction (RT-PCR). In the treatments of 4.0, 6.0 and 8.0u202fmgu202fkg-1, the abundance of amoA genes of the AOA- and AOB- were inhibited by IL [Omim]PF6.

Effects of the herbicide mesotrione on soil enzyme activity and microbial communities

Mesotrione (2-[4-(methylsulfonyl)-2-nithobenzoyl]-1, 3-cyclohexanedione) is a selective triketone herbicide that has been widely used in corn production for the past 15 years. However, its potential for risk to soil ecosystems is poorly documented. The present study investigated the soil enzyme activity and soil microbial community responses to a 20 days mesotrione exposure at doses of 0.1, 1.0 and 5.0u202fmg/kg. On days 2, 5, 10 and 20, activities of soil β-glucosidase, urease and acid phosphatase, soil microbe abundances, soil microbial community structure and abundance of the AOA-amoA and AOB-amoA genes were measured. Results showed that activities of urease and acid phosphatase were relatively stable, with no difference found between the mesotrione-treated group and control at the end of exposure. But β-glucosidase activity was reduced in the 5.0u202fmg/kg mesotrione treatment. In the 1.0 and 5.0u202fmg/kg mesotrione-treated soil, abundance of bacteria, fungi and actinomycetes all were reduced. In the 0.1u202fmg/kg mesotrione-treated soil, only fungi abundance was reduced by the end of the exposure. The analysis of terminal restriction fragment length polymorphism (T-RFLP) revealed soil microbial community structure could be affected by mesotrione at all experimental doses, and microbial diversity declined slightly after mesotrione exposure. Abundance of AOA-amoA and AOB-amoA genes were reduced markedly in 1.0 and 5.0u202fmg/kg mesotrione-treated soil. The present study suggests that mesotrione at higher doses might induce negative impacts on soil microbes, a finding which merits additional research and which should be accounted for when application of this herbicide is considered.