[Transport behaviors of metal oxide nanomaterials in various soils]

Transport behaviors of nano-CeO2, nano-TiO2 and nano-Al2O3 materials in various soils were investigated by column leaching experiment. The relationship between transportability of nanomaterials and soil properties was analyzed and potential transport distances of nanomaterials in soils were estimated by applying the colloid migration dynamic model. The result shows that both nano-CeO2 and nano-TiO2 have strong mobility in most of tested soils. While nano-Al2O3 is almost completely retained in most of tested soils except acidic soil, in which nano-Al2O3 shows relatively strong transportability. The transport mechanisms of nanomaterials in soils are very complicated. Among electrostatic interaction, soil surface charge heterogeneities, aggregation, straining and ripening, each of them plays an important role in the transport of nanomaterials. The transportability of nano-CeO2 is negatively correlated with soil Zeta potential, while that of nano-TiO2 is negatively correlated with soil clay content, and positively correlated with soil permeability coefficients. The transportability of nano-Al2O3 is negatively correlated with soil pH, and positively correlated with soil permeability coefficients. The estimated maximum transport distances of nano-CeO2, nano-TiO2 and nano-Al2O3 materials in soils were 526,9043 cm, 31-332 cm and <10-5,722 cm, respectively. The estimated potential transport distances of nanomaterials in some soils are far more than the surface soil depth of 30 cm, indicating severe risks to deeper soil layers would potentially occur in these soils.