Terrestrial ecotoxicity of short aliphatic protic ionic liquids.

A study of the ecotoxicity of different short aliphatic protic ionic liquids (PILs) on terrestrial organisms was conducted. Tests performed within the present study include those assessing the effects of PILs on soil microbial functions (carbon and nitrogen mineralization) and terrestrial plants. The results show that the nominal lowest-observed-adverse-effect concentration (LOAEC) values were 5,000 mg/kg (dry soil) for the plant test in two species (Lolium perenne, Allium cepa), 1,000 mg/kg (dry soil) for the plant test in one species (Raphanus sativus), and 10,000 mg/kg (dry soil) for carbon and nitrogen microbial transformation tests (all concentrations are nominal). Most of the median effective concentration values (EC50) were above 1,000 mg/kg (dry soil). Based on the obtained results, these compounds can be described as nontoxic for soil microbiota and the analyzed plants, and potentially biodegradable in soils, as can be deduced from the respirometric experiment. The toxicity rises with the increase of complexity of the PILs molecule (branch and length of aliphatic chain) among the three PILs analyzed.