Comparative Study on Volatile Oils among Bupleuri radix Species and Habitats: Yields, Chemical Characterization and Antipyretic Activities.

Volatile oils from several Bupleuri radix (BR) are reported as potential sources of drugs. To provide evidence for the application of BR, the volatile oils from 19 batches of different species and habitats of BR including Bupleurum chinese DC. (BCD), Bupleurum scorzonerifolium Willd. (BSW), Bupleurum bicaule Helm (BBH), Bupleurum marginatum var. stenophyllum (Wolff) Shan et Y.Li (BMS), Bupleurum marginatum Wall.ex DC. (BMW) and Bupleurum falcatum L. (BFL) were investigated. The composition of BR volatile oils was determined by GC/MS. Samples were clustered by hierarchical cluster analysis (HCA). Fever was induced by Lipopolysaccharide (LPS), and antipyretic activities of BR volatile oils were evaluated with Chaihu injection (CI) as the positive control. The yields of volatile oils were among 360-5320 ppm. A total of 229 components were identified by GC/MS. Samples could be divided into 4 clusters by HCA. 4 representative samples, one for each cluster, were selected to further compare their antipyretic activities. For the highest content of volatile oil (5320 ppm) and the best activity, BSW has great potential for utilization.

Enhanced mobilization of Cd from commercial pigments in the rhizosphere of flooded lowland rice.

Although yellow Cd pigments (Cd-YP), widely used in industrial colorants, are considered inert, increasing evidence suggests once released into the environment, photobleaching/weathering mobilizes Cd from these pigments posing a pollution threat. Although general redox conditions and biotic/microbial activity are known to be important factors in determining Cd release, how spatial trends and specific soil processes regulate the Cd-YP behavior are poorly understood. Using plant rhizotrons in controlled environmental conditions, this study investigated the behavior of Cd-YP amendments matched to levels (15 mg kg-1) representative of contaminated soils in Yixing, China. Using high-resolution two-dimensional diffusive-gradient-in-thin-films (HR-2D-DGT), planar-optode (PO) multilayer systems alongside targeted soil and porewater sampling for chemical analysis the biogeochemistry associated with Cd mobilization from Cd-YP rice rhizospheres were determined. The results showed that there was a significant release of Cd into soil porewaters (51.5 µg L-1), but this reduced by 90.9% and stabilized over time (after 6-days). HR-2D-DGT ion-maps revealed pronounced spatial variances. The flux-maxima for Cd, which located within aerobic-rhizosphere zones, was 9 to 19-fold higher than in associated anoxic bulk soil. In general, zones of radial O2 loss (ROL)/higher redox conditions and lower pH were associated with Cd release, with S2- to SO42- transitions marking the boundaries of high-flux areas. Some isolated colocalization of Fe and Cd hotspots were observed in lateral root regions, but on-the-whole Fe/Mn and Cd release were not linked. In addition, microniche development was also an important feature of Cd mobilization due to soil heterogeneity.

Influence of electrode configuration on electrokinetic-enhanced persulfate oxidation remediation of PAH-contaminated soil.

Electrokinetic (EK) remediation combined with in situ chemical oxidation (ISCO) can be applied to low permeability organic contaminated soil. However, the effects of electrode configuration on EK-oxidation remediation remain unclear. In this study, EK-ISCO remediation of real polycyclic aromatic hydrocarbon (PAH)-contaminated soil under different electrode configurations was conducted. The results showed that increasing the number of anodes and electrode pairs in one-dimensional (1D) and two-dimensional (2D) electrode configuration was conducive to migration of oxidants into the system. The change in soil pH after remediation in 2D electrode configuration was not obvious, but the increase of soil electrical conductivity (EC) was higher than that of the 1D electrode configuration. The removal rates of PAHs in 2D electrode configurations (35.9-40.9%) were relatively higher than those of the 1D electrode configurations (0.54-31.6%), and the hexagonal electrode configuration yielded the highest pollutant removal efficiency, reaching 40.9%. The energy consumption under 2D electrode configuration was smaller than that under 1D electrode configuration, and the energy consumption of per gram removed PAHs in the hexagon configuration (66.74 kWh (g PAHs)-1) was lowest in all electrode configurations. Overall, the results of this study suggest that 2D electrode configuration is better than 1D and hexagonal electrode configuration is an optimal electrode configuration.

Ion exchange membranes enhance the electrokinetic in situ chemical oxidation of PAH-contaminated soil.

Electrokinetic in situ chemical oxidation (EK-ISCO) could be used to remediate inorganic/organic-contaminated soil. Oxidizing agents were effectively delivered to the contaminated zones through electromigration and the electroosmosis. However, the cathode may react with oxidants, which would reduce the oxidative effect and lead to low contaminant removal rates. In this study, ion-exchange membranes (IEMs) enhanced EK-ISCO was used to remediate polycyclic aromatic hydrocarbons (PAHs) in contaminated soil. IEMs were installed between the electrode compartment and the soil compartment. The results showed that the IEMs could effectively control pH and the oxidation-reduction potential (ORP) changes in the soil column. Placing a cation-exchange membrane (CEM) at the cathode prevented the S2O82- from contacting the cathode and reduced the oxidative loss effect, which meant that PAH removal efficiency significantly improved (from 33.1% to 87.1%). Furthermore, there were minimal changes to the soil properties. Maintaining the soil at a low pH also improved the PAH removal efficiency (93.1%), but the physicochemical properties of the soil significantly changed and a large amount of power was consumed (2015 kWh t-1). This study indicated that placing a CEM at the cathode improved remediation efficiency, and reduced power consumption and the adverse effects on soil properties during EK-ISCO.

Migration and decomplexation of metal-chelate complexes causing metal accumulation phenomenon after chelate-enhanced electrokinetic remediation.

This study investigates the migration and decomplexation effects of metal-ethylenediaminetetraacetic acid (EDTA) complexes during an electrokinetic (EK) remediation process and the resulting metal accumulation phenomena. Six EK tests with control of the electrolyte pH and using ion-exchange membranes were performed to treat Pb-EDTA and Cd-EDTA co-contaminated red soil. The obtained results showed that a portion of free metal cations could be decomplexed from the metal-EDTA complexes due to the low pH and electrochemical degradation at the anode. These cations went back into the soil by electromigration and accumulated in separate locations according to their hydrolysis ability and the distribution of soil pH in different sections. Totals of 61% Cd and 83% Pb were removed from the soil after a 7-day treatment under the condition of controlling the electrolyte pH at 10. The removal efficiencies of metals under the anion-exchange membrane-assisted treatment were higher than those of the cation-exchange membrane-assisted treatment. Based on the mechanisms of metal accumulation phenomena, the migration of decomplexed free metal cations back to the soil is limited by using an anion-exchange membrane or pre-precipitation with alkaline conditions was confirmed to effectively reduce the effect of metal accumulation.