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As one of the typical actinide elements, the chemical and radioactive toxicities of uranium have attracted more attention. In this work, the toxicity mechanism of uranium-238 in HK-2 cells was studied in detail using in vitro approach. The results confirmed that exposure to uranium solution significantly reduced the viability of HK-2 cells. Flow cytometry and double fluorescence AO/PI staining suggested that apoptosis was the main cause of the death of HK-2 cells. Moreover, reactive oxygen species and mitochondrial membrane potential tests further demonstrated that HK-2 cells underwent apoptosis under the combined action of oxidative stress and mitochondrial damage. The tails in the comet assay and the abnormal nuclear morphology in DAPI staining confirmed the genotoxicity of uranium to HK-2 cells. In conclusion, uranium mainly causes apoptosis and genotoxicity after exposure, and the main mechanisms of apoptosis are mainly related to oxidative stress, mitochondrial damage, and DNA damage. [ABSTRACT FROM AUTHOR]

In this study, the sorption of U(VI) on the farming soil (FS) and natural soil (NS) collected from northwest China was studied using batch and spectroscopic approaches. The sorption of U(VI) on NS, FS, decarbonated NS (DNS) and decarbonated FS (DFS) quickly increased with the pH increased. After removing carbonates, U(VI) sorption on DFS and DNS became slightly lower. The exchangeable fraction was the highest in NS, FS, DNS, and DFS. However, it was noted that the carbonate fraction took up 13–17% in FS and NS, suggesting that carbonate has an essential impact on the species distribution. [ABSTRACT FROM AUTHOR]

The sorption of Ni(II) on a calcareous aridisol (CA) soil, one of the major soil types in northwestern China, was investigated using batch and extended X-ray absorption fine structure (EXAFS) approaches in a 0.01 mol/L NaClO4 solution at different pH values (6.0-10.0), temperatures (25-60 °C) and contact times (2-15 days). Under alkaline conditions, EXAFS analysis showed that the interatomic distances between Ni and O atoms (RNi-O) were approximately 2.04 Å with a typical coordination number (CN) of ~6.0 O atoms in the contact time range from 2 to 15 days. The RNi-Ni (~3.07 Å) suggested that the structure of the Ni(II) adsorbed on the CA soil was basically the same as that of Ni(OH)2(s), while the Ni-Al shell (RNi-Al ~3.16 Å) gradually formed and grew with the increasing contact time. Under weakly acidic conditions, the sorption mechanism of Ni(II) on the CA soil possibly included at least two processes: (i) a fast accumulation dominated by ion exchange and surface complexation and (ii) the formation of a Ni-Al LDH phase over the long term. A high temperature is beneficial to the fixation of Ni(II) on the CA soil and the formation of a Ni-Al LDH. [ABSTRACT FROM AUTHOR]