Sensitivity of soil dehydrogenase and FDA activities to the ionic liquid ethylammonium nitrate and its lithium salt

SIXTO, TERESA; SEOANE, SOCORRO; BELLO, DIANA; PRIANO, MARÍA EUGENIA; TRASAR-CEPEDA, CARMEN

Porto

Congreso; 2nd International Meeting on New Strategies in Biorremediation Processes; 2019

Ionic liquids (ILs) are salts formed by one organic cation and one organic or inorganic anion with melting point below 100 ºC. Because of their negligible volatility, ILs are usually considered as ?non-toxic? and frequently are denominated as ?green fluids?. However, the fact that are not toxic for the atmosphere does not mean they are also innocuous for aquatic and terrestrial environments. Despite this, the number of studies about the toxic effects of ILs on soils is very limited. Due to their thermophysical properties, these compounds have potential use in numerous applications. Ethylammonium nitrate (EAN) and its lithium salt (EAN-Li) are two ILs being investigated for their use as electrolytes for batteries. Soil enzyme activities are highly sensitive parameters to detect any perturbation in soil functioning and therefore could potentially be used as biochemical indicators of ILs toxicity. In this study, the effect EAN and EAN-Li on soil dehydrogenase and fluorescein diacetate (FDA) activities was investigated. With this purpose, two acidic soils with similar pH and different organic matter content (agricultural and forest) were spiked with increasing amounts of the two compounds, and after three days the activities of both enzymes were analysed. Dehydrogenase activity tended to decrease and FDA to increase with increasing amounts of both ILs, but the extent of the decrease depended on the activity, the IL and the soil. In all cases, dehydrogenase decreased and FDA increased. enerally, dehydrogenase activity and the forest soil were more strongly affected than FDA and the agricultural soil.