MOBILITY OF CERIUM DIOXIDE NANOPARTICLES IN SOILS AT DIFFERENT EXPOSURE SCENARIOS

Abstract

Nowadays, widespread application of engineered nanoparticles (ENPs) inevitably leads to their release into the environment. Soils are regarded as the ultimate sink for ENPs. The study on the mobility of ENPs in soils is important in the assessment of potential risks related to their toxicity. The behavior of ENPs depends not only on the parameters of soil, but also on the exposure scenarios, namely, the amount of ENPs trapped in soil. We studied the mobility of cerium dioxide nanoparticles (nCeO2) in soils at different exposure scenarios. The relationship between the mobility of nCeO2and their concentration in the soil within the range 1 – 1000 ìg/g is evaluated. It is shown that the mobility of nCeO2decreases with a decrease in their concentration in the soil and attains the minimum value when the concentration of nCeO2goes below 10 ìg/g. In relative units, only about 0.1 – 0.2% of nCeO2(in aforementioned concentration range) exhibit mobility and can migrate in the soil profile under saturated conditions. The lion’s share of nCeO2(about 99.8%) remains immobile in the soil. Evidently, the vertical transport of nCeO2in soil profile should depend on the volume of released suspensions. In the case of small or moderate wet deposition, nanoparticles will accumulate in upper soil horizons characterized with the highest biological activity and thus can affect the soil inhabitants (plant roots, earthworms, insects, microorganisms, etc.).