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The coastal soil surrounding to the Nuclear Power Plants were mainly classified to brown soil and aeolian sandy soil in China. In previous research, focused on the elements of Cs-137 and Sr-85 vertical transfer in these soils, but the Co-60, which was the most important factor in the brown soil and aeolian sandy soil were still urgent research. In this study, experiments were conducted to determine the vertical transfer of Co-60 in brown soil and aeolian sandy soil. The soil around Shidaowan Nuclear Power Plant were studied by using undisturbed soil column methods and isotope tracer technology, and identify the factors influencing their migration depths in soil. The results show that with the increase of leaching test, the migration of Co-60 in aeolian sandy soil was greater than that in brown soil, but the difference gradually decreases with the progress of spray test; the content of Co-60 in leaching water was very few and cannot be detected due to the strong adsorption by soil; after three years of undisturbed soil column experiment, 72.36 ∼ 85.26% of Co-60 mainly was retarded in the range of 0∼5cm in both of the soil surface. It was proved that Co-60 was difficult to migrate to groundwater in a short period. The distribution of specific activity of Co-60 in soil was an individual exponential declining with depth of oil. The results showed that the radionuclide Co-60 had little impact on groundwater in the years after the nuclear accident, but it should pay attention to the change of radioactivity concentration in surface soil and then select appropriate soil remediation methods. The study will provide a scientific basis for post-accident environmental impact assessment and post-accident soil remediation in China.

Humic substances (HS) substantially affect heavy metal (M) adsorption on mineral surfaces. However, quantitative descriptions of ternary systems involving M, HS and mineral surfaces remain unclear. This study examines adsorption in a model ternary system including Eu(III), fulvic acid (FA) and silica, and describes the adsorption of Eu(III) and FA by combining a double-layer model (DLM) and the Stockholm humic model (SHM). SHM explains the binding of H+ and Eu3+ to FA and the DLM for FA and Eu(III) adsorption on silica. Experimental results showed that the presence of FA promotes Eu(III) adsorption at acidic pH values, but decreases it at basic pH values, which indicates the formation of ternary surface complexes. Modeling calculations have shown that two ternary surface complexes are required to describe the experimental results in which Eu3+ acts as a bridge between the surface site and FA. The present study suggests that the discrete-site approach to HS is a promising method for interpreting the adsorption data for M, HS and mineral ternary systems.

With the large-scale study and application of graphene and ionic liquids (ILs), it was imperative to clarify their interaction mechanism with the environment. The graphene oxides (GO) with different oxygen content were obtained using electron beam irradiation and chemical reduction. Then, batch adsorption experiments were preformed to understand the adsorption behavior of ILs on GO with different oxygen content. Experimental results show that the adsorption capacity of ILs on GO depends strongly on the oxygen level of graphene and the ionic strength of the solution, GO of rich and poor oxygen presented better performance at high and low ionic strength, respectively, which is owing to the formation of chemical bonds between ILs and oxygen groups on GO. Moreover, ILs possess aromaticity and cationic properties, both of which favor the adsorption of ILs on GO. Competitive adsorption of two ILs on GO with poor oxygen content was observed; but it was found that one IL could promote the adsorption of the other ILs on GO of rich oxygen content, which could be attributed to the properties of ILs and GO. This work may advance the understanding of the adsorption behavior of ILs on graphene oxide and find a possible way to remove ILs in the environmental systems.