The longevity evaluation of multi-metal stabilization by MgO in Pb/Zn smelter-contaminated soils.

The re-mobilization risks of potentially toxic elements (PTEs) during stabilization deserve to be considered. In this study, artificial simulation evaluation methods based on the environmental stress of freeze-thaw (F-T), acidification and variable pH were conducted to assess the long-term effectiveness of PTEs stabilized by MgO in Pb/Zn smelter contaminated soils. Among common stabilizing materials, MgO was considered as the best remediation material, since PTEs bioavailability reduced by 55.48% for As, 19.58% for Cd, 10.57% for Cu, and 26.33% for Mn, respectively. The stabilization effects of PTEs by MgO were best at the dosage of 5 wt%, but these studied PTEs would re-mobilize after 30 times F-T cycles. Acid and base buffering capacity results indicated that the basicity of contaminated soils with MgO treatment reduced under F-T action, and the leached PTEs concentrations would exceed the safety limits of surface water quality standard in China (GB3838-2002) after acidification of 2325 years. No significant changes were found in the pH-dependent patterns of PTEs before and after F-T cycles. However, after F-T cycles, the leaching concentrations of PTEs increased due to the destruction of soil microstructure and the functionality of hydration products formed by MgO, as indicated by scanning electron microscopy (SEM) coupled with energydispersive Xray spectroscopy (EDS) results. Hence, these findings would provide beneficial references for soil remediation assessments of contaminated soils under multi-environmental stress.

The occurrence of "yellowing" phenomenon and its main driving factors after the remediation of chromium (Cr)-contaminated soils: A literature review.

Chromium (Cr) is a highly toxic element, which is widely present in environment due to industrial activities. One of most applicable technique to clean up Cr pollution is chemical reduction. However, the Cr(VI) concentration in soil increases again after remediation, and meanwhile the yellow soil would appear, which is commonly called as "yellowing" phenomenon. To date, the reason behind the phenomenon has been disputed for decades. This study aimed to introduce the possible "yellowing" mechanism and the influencing factors based on the extensive literature review. In this work, the concept of "yellowing" phenomenon was explained, and the most potential reasons include the reoxidation of manganese (Mn) oxides and mass transfer were summarized. Based on the reported finding and results, the large area of "yellowing" is likely to be caused by the re-migration of Cr(VI), since it could not sufficiently contact with the reductant under the effects of the mass transfer. In addition, other driving factors also control the occurrence of "yellowing" phenomenon. This review provides valuable reference for the academic peers participating in the Cr-contaminated sites remediation.

Off-hours admission does not impact outcomes in patients undergoing primary percutaneous coronary intervention and with a first medical contact-to-device time within 90 min / 中华医学杂志(英文版)

BACKGROUND@#It remains unclear whether the outcomes of ST-elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PPCI) during off-hours are as favorable as those treated during on-hours, especially those with a first medical contact-to-device (FMC-to-device) time within 90 min. We aimed to determine whether off-hours admission impacted late outcomes in patients undergoing PPCI and with an FMC-to-device time ≤90 min.@*METHODS@#This multicenter retrospective study included 670 STEMI patients who underwent successful PPCI and had an FMC-to-device time ≤90 min from 19 chest pain centers in Beijing from January 2018 to December 2018. Patients were divided into on-hours group and off-hours group based on their arrival time. Baseline characteristics, clinical data, and key time intervals during treatment were collected from the Quality Control & Improvement Center of Cardiovascular Intervention of Beijing by the "Heart and Brain Green Channel" app.@*RESULTS@#Overall, the median age of the patients was 58.8 years and 19.9% (133/670) were female. Of these, 296 (44.2%) patients underwent PPCI during on-hours and 374 (55.8%) patients underwent PPCI during off-hours. Compared with the on-hours group, the off-hours group had a longer FMC-to-device time and fewer patients with FMC-to-device time ≤60 min (P  0.05). According to the Cox regression analyses, off-hours admission was not a predictor of 2-year MACEs (P = 0.788). Similarly, the Kaplan-Meier curves showed that the risks of a MACE, all-cause death, reinfarction, and target vessel revascularization were not significantly different between the two groups (P > 0.05).@*CONCLUSIONS@#This real-world, multicenter retrospective study demonstrated that for STEMI patients who underwent PPCI within 90 min, off-hours admission was safe, with no difference in the risk of 2-year MACEs compared with those with on-hours admission.