Ecological effects of ionic liquids on microbial activity of a soil and on tree seed germination

Resumo

Ionic liquids (ILs) are considered one of the most promising green alternatives to molecular organic solvents. Nevertheless, before a widespread use of these compounds in a determined application, the knowledge of their ecotoxicity and biodegradability must be defined.In this work the effect of addition of different doses of 1-butil-2,3-dimethylimidazolium trifluoromethanesulfonate, [C4C1C1Im][OTf], on microbial activity of a soil under Pinus pinaster Aiton and on the seed germination of species of P. pinaster , Pinus sylvestris L., Pinus radiata D. Don and Eucalyptus globulus Labill were analyzed. Additionally, seed germination test were also applied to this IL after being subjected to heat treatment.A microcalorimeter Thermal Activity Monitor (TAM-III) TA-Instruments was used to determine the influence of the addition of four doses (10 %, 25 %, 50 % and 75 %) on the microbial activity of a Galician soil, under P. pinaster. Methodology was widely exposed in previous works [1]. From the data obtained in these experiments, the calculation of microbial growth was performed [2].Seed germination test of selected species were carried out for several doses of ILs (10 %, 1 %, 0.1 % and 0.01 %). The degradation treatment of the IL was carried out during 24 h in an oven at the temperature of 200 °C. Five replies with 25 seeds per Petri dish were incubated in a Phytotron (Climas AGP890) for every species and treatments. Seeds were maintained for 16 h under light at 24 °C and in the dark for 8 h at 16 °C during 45 days, when the germination was completed in all the species [3, 4].Results of soil microbial activity and germination obtained for this IL were compared with the corresponding to other ILs, previously studied in our laboratory. Dose of 10 % inhibited totally the germination of the four species and dose of 1 % provoked an important reduction with regard to the control, both, for degraded and no-degraded IL. Nevertheless, in spite of all the doses showed differences on calorimetric parameters with regard to control; only the dose of 75 % does not show soil microbial response.