A comparative study of DNAPL migration and transformation in confined and unconfined groundwater systems.

To explore the migration and transformation process of dense non-aqueous liquid (DNAPL) pollutants' multiphase flow, specifically nitrobenzene (NB), in confined groundwater (CG) versus unconfined groundwater (UG), a two-dimensional sandbox experimental device was designed and constructed. This involved constructing a vadose zone-UG- aquitard-CG structure, which was then subjected to different scenarios. Real-time analysis and numerical simulation methods were established and employed, with a particular focus on the detailed investigation results of actual contaminated site. The study found that when the same amount of NB was injected, the special structure of the CG layer resulted in a more pronounced reverse diffusion of NB in both the dissolved and NAPL phases. This was especially true for the dissolved phase, which was more likely to diffuse reversely. Meanwhile, CG did not directly interact with the vadose zone, and there was no loss of gas phase NB after the leakage in CG. As a result, higher concentrations of dissolved phase NB were generated, leading to the emergence of a larger area of NB contaminant plumes with CG flow. Importantly, the simulation study of the actual site and the laboratory experimental results were found to be validated, further validating the conclusion that direct leakage of NB into CG results in a higher concentration and larger area of dissolved phase contaminant plume, causing more serious pollution to the groundwater environment.

Effects of compost-derived humic acid on the bio-dechlorination of pentachlorophenol in high iron content paddy soil.

Pentachlorophenol (PCP) is a common residual organic pollutant in paddy soil, and its harmful effects on soil ecosystems have been confirmed. Humic acid (HA) could act as an electron shuttle to promote the reductive dechlorination of PCP under anaerobic conditions. Humic-like substances produced by composting of kitchen waste were able to facilitate the reductive dechlorination of PCP during Fe(III) oxide reduction by iron-reducing bacteria. However, the effects of compost-derived HAs on reductive dechlorination of PCP in a paddy soil system with a high iron content have not been fully confirmed. The characteristics of HAs from different stages of composting during bio-dechlorination of PCP were still unclear. The functional components of compost-derived HAs, which are responsible for reductive dechlorination of PCP in different stages of composting, also need further investigation. In this study, we conducted a series of experiments on the Guangdong paddy soil system with high iron content (17.5 mg kg-1) to investigate the reductive dechlorination of PCP by HA in the early, middle, and later stages of food waste composting. The results showed that the middle- and late-stages of compost-derived HAs all promoted reductive dechlorination of PCP in the paddy system, but it was opposite in the early-stage. Significant differences were also presented in the components of HAs from different stages of composting. The early-stage compost-derived HAs contain numerous easy degradable components, it would inhibit the dechlorination of PCP by the changes of microbial metabolism in paddy soil. Compost-derived HAs in the middle composting stage showed the best reductive dechlorination effects on PCP. The reason might be that the compost-derived HAs in the middle composting stage could act both as electron donors and transfers. The electron transfer capacities (ETC) of middle-stage compost-derived HAs were significantly higher than those in the early and later composting stages. Compared with the natural HAs in the soil system, compost-derived HAs contained more chlorinated products with lower toxicities after the PCP degradation. This result mainly contributed to the detoxification and mineralization of PCP in the soil. These findings clarified the effects of compost-derived HAs on PCP bio-dechlorination in paddy soil with high iron content, identifying the optimal phase of compost-derived HA and providing a theoretical basis for the utilization of kitchen waste composting as a resource of HA.

Effect of water-level fluctuation on the removal of benzene from soil by SVE.

In areas that experience frequent fluctuations in groundwater levels, changes in soil void space caused by fluctuations in groundwater levels directly affect the efficacy of soil vapor extraction (SVE). Most studies of SVE technology of oil-contaminated soil remediation do not consider fluctuations in groundwater levels. Here, we constructed an experimental device to study the removal of benzene by SVE under fluctuating groundwater levels. Key parameters affecting the remediation effect of SVE, such as the extraction flow, extraction time, extraction method, initial soil moisture content and initial pollutant content, were studied to characterize their effects on the efficacy of benzene removal by SVE under stable and fluctuating groundwater levels. The removal rate of benzene by SVE was approximately 10% higher under fluctuating water levels than under stable water levels. Extraction flow can directly change the removal rate under fluctuating groundwater levels. Under fluctuating groundwater levels, the removal effect of SVE on benzene in different soils of the "stabilization zone - fluctuation zone - saturation zone" also significantly differed; specifically, the removal effect of SVE in the fluctuation zone and stabilization zone was superior to that in the saturation zone. Given the fluctuation in groundwater levels at the study site, the remediation.

Patients with systemic lupus erythematosus show increased proportions of CD19+CD20- B cells and secretion of related autoantibodies.

BACKGROUND: At present, anti-CD20 monoclonal antibody treatments targeting systemic lupus erythematosus (SLE) are complex, variable, and often have disappointing outcomes. High levels of programmed cell death-1 (PD-1) and its ligands (PD-L1, PD-L2) or CD80/CD86 on B cell surfaces are markers of increased B cell activity. However, their expression levels on CD19+CD20+/- B cells and their clinical significance for SLE dynamics have not been carefully investigated. METHODS: Flow cytometry was used to detect the expression levels of PD-1, PD-L1, PD-L2, CD80, and CD86 on CD19+CD20+/- B cells in peripheral blood from SLE patients and healthy controls (HCs). The amount of anti-dsDNA and immunoglobin G (IgG) secreted by CD19+CD20+/- B cells was measured by enzyme-linked immunosorbent assay. RESULTS: CD19+CD20- B cell frequency was significantly higher in SLE patients than in HCs (P < 0.001), and was positively correlated with disease activity. In SLE patients, frequencies of PD-1, PD-L1, PD-L2, and CD86 on CD19+CD20- B cells were significantly higher than CD19+CD20+ B cells (P ≤ 0.002) and were significantly correlated with individual laboratory and clinically based parameters (P < 0.05). In vitro tests, we found that the levels of anti-dsDNA and IgG secreted by CD19+CD20- B cells from patients with SLE were significantly higher than the HC group (P < 0.05). CONCLUSIONS: We found abnormal frequency of CD19+CD20- B cells and increased expression of surface markers on these cells from SLE patients. And the CD19+CD20- B cells had the ability to proliferate and secrete anti-dsDNA and IgG. Additionally, our results suggested that CD19+CD20- B cells from SLE patients may be the activated B cells and caused poor efficacy of rituximab. Key Points • CD19+CD20- B cell frequencies were significantly higher in SLE patients. • Frequencies of PD-1 and its ligands on CD19+CD20- B cells increased significantly in SLE patients. • CD19+CD20- B cells in SLE patients had the ability to secrete anti-dsDNA and IgG. • CD19+CD20- B cells in SLE patients may be the activated B cells and caused poor efficacy of rituximab.

A study of layered-unlayered extraction of benzene in soil by SVE.

With the aim to improve the pollution removal efficiency, a layered extraction simulation device for the removal of benzene-contaminated soil via soil vapor extraction was constructed. The removal of benzene from soils by both layered extraction and unlayered extraction was explored based on the factors of extraction flow, extraction time, initial contaminant content, initial soil moisture content, and extraction method. Under the same conditions, layered extraction improved the repair efficiency, shortened the repair time, and decreased the cost of repair. Different factors exerted different influences on the extraction effect, but overall, compared with unlayered extraction, the removal rate of layered extraction can be increased by 2-20%. In particular, when the content of benzene was high, layered and intermittent extraction could remove more than 90% of benzene from the soil. When layered extraction was adopted, the pressure loss in the lower part of the soil layer was small and the air flow into the soil was large, which can promote the volatilization of benzene and thus improve its removal rate.