A new alkylphosphine ligand HEDTMP is synthesized and a promisingly radiotherapeutic complex 188ReHEDTMP is prepared. The adsorption characteristics of the complex on HA are investigated. It's found that time, amount of HEDTMP and pH have remarkable influences, while temperature has little influence on the adsorption of 188ReHEDTMP on HA, and the best adsorption condition is shown to be t=10 min, n(HEDTMP)∶n(Re)=50∶1 with pH=1.5. The adsorption stability of 188ReHEDTMP on HA is good.
A lack of knowledge about antimony (Sb) isotope fractionation mechanisms in key geochemical processes has limited its environmental applications as a tracer. Naturally widespread iron (Fe) (oxyhydr)oxides play a key role in Sb migration due to strong adsorption, but the behavior and mechanisms of Sb isotopic fractionation on Fe (oxyhydr)oxides are still unclear. Here, we investigate the adsorption mechanisms of Sb on ferrihydrite (Fh), goethite (Goe), and hematite (Hem) using extended X-ray absorption fine structure (EXAFS) and show that inner-sphere complexation of Sb species with Fe (oxyhydr)oxides occurs independent of pH and surface coverage. Lighter Sb isotopes are preferentially enriched on Fe (oxyhydr)oxides due to isotopic equilibrium fractionation, with neither surface coverage nor pH influencing the degree of fractionation (Δ123Sbaqueous-adsorbed). Limited Fe atoms are present in the second shell of Hem and Goe, resulting in weaker surface complexes and leading to greater Sb isotopic fractionation than with Fh (Δ123Sbaqueous-adsorbed of 0.49 ± 0.004, 1.12 ± 0.006, and 1.14 ± 0.05‰ for Fh, Hem, and Goe, respectively). These results improve the understanding of the mechanism of Sb adsorption by Fe (oxyhydr)oxides and further clarify the Sb isotope fractionation mechanism, providing an essential basis for future application of Sb isotopes in source and process tracing.
In order to identify the contamination and health risks of heavy metals in agricultural soils, a total of 56 surface soil samples (0-20 cm) were collected around a Pb-Zn smelter in Yunnan Province, and six heavy metals (Pb, Cd, Zn, As, Cu, and Hg) and pH were analyzed to assess heavy metal status, ecological risk, and probabilistic health risk. The results revealed that the average contents of six heavy metals (Pb:4413.93 mg·kg-1, Cd:6.89 mg·kg-1, Zn:1672.76 mg·kg-1, As:44.45 mg·kg-1, Cu:47.61 mg·kg-1, and Hg:0.21 mg·kg-1) were higher than their background values in Yunnan Province. Cd had the highest mean geo-accumulation index (Igeo) of 0.24, the highest mean pollution index (Pi) of 30.42, and the greatest average ecological risk index (Er) of 1312.60, indicating that Cd was the primary enriched and highest-ecological risk pollutant. The mean hazard index (HI) through exposure to six HMs was 2.42E-01 and 9.36E-01 for adults and children, respectively, with 36.63% of HI values for children exceeding the risk threshold of 1. Moreover, the mean total cancer risks (TCR) were 6.98E-05 and 5.93E-04 for adults and children, respectively, with 86.85% of TCR values for children exceeding the guideline value of 1E-04. The probabilistic health risk assessment suggested that Cd and As were the main contributors for the non-carcinogenic risks and carcinogenic risks. This work will provide scientific reference for the precise risk management and effective remediation strategy of soil heavy metal pollution in this study area.
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