[Show abstract][Hide abstract] ABSTRACT: Antimony (Sb) has received increasing environmental concerns due to its potential toxic and carcinogenic properties. In the present work, the electrocoagulation technique was used to treat the flotation wastewater from a heavy antimony polluted area, and the mechanism of removing Sb was also investigated. The study focused on the effect of operation parameters such as current density, initial pH and standing time on the Sb removal efficiency. Antimony concentration of below 1 mg/L in the treated wastewater was achieved, which meets the emission standards established by State Department of Environmental Protection and State Administration of China for Quality Supervision and Inspection and Quarantine of China.
[Show abstract][Hide abstract] ABSTRACT: Antimony (Sb) distribution and accumulation in plants in Xikuangshan Sb deposit area, the only one super-large Sb deposit in the world, Hunan, China were investigated. Results show that soils were severely polluted with the average Sb concentrations up to 5949.20 mg kg− 1. Sb widely occurred in 34 plants with various concentrations ranging from 3.92 mg kg−1 to 143.69 mg kg− 1, Equisetaceae family has the highest concentration (98.23 mg kg− 1) while Dryopteridacea family has the lowest one (6.43 mg kg− 1). H. ramosissima species of Equisetaceae family had the highest Sb average concentration of 98.23 mg kg− 1 and P. vittata species of Pteridaceae family showed advantage of accumulating Sb from the contaminated environment (Biological Accumulation Coefficient, BAC = 0.08). Almost all species enriched Sb in their upground part such as shoot, leaf and flower (Biological Transfer Coefficient, BTC > 1), which may attribute to the high acropetal coefficient and Sb transformation from the atmosphere to the plants. P. phaseoloides and D. indicum showed predominantly accumulation of Sb in the upground part with BTC of 6.65 and 5.47, respectively.From the low bioavailable fraction in soils and weak relationship between total soil concentrations in soils and plants, it seems that the Sb bioavailability was limited and varied with different soil sites as well as plant species. Those observations would be significant to the phytoaccumulation and phytoremediation of plants and ecological and environmental risk assessment in Sb contaminated areas.
No preview · Article · Jan 2011 · Microchemical Journal
[Show abstract][Hide abstract] ABSTRACT: To study the effect of the environmental pollution in exposed population, human hair samples of residents were collected from two typical antimony mines (Xikuangshan antimony mine and Qinglong antimony mine, Southwest China) and one non-mining city (Guiyang, Southwest China), and the concentrations of arsenic, antimony and bismuth in these samples were analyzed by hydride generation-atomic fluorescence spectrometry. Arsenic concentrations for Xikuangshan, Qinglong, and Guiyang ranged 0.236–48.4 (mean 4.21), 0.130–16.1 (mean 2.96), and 0.104–0.796 (mean 0.280) μg/g, respectively. Antimony concentrations for Xikuangshan, Qinglong, and Guiyang ranged 0.250–82.4 (mean 15.9), 0.060–45.9 (mean 5.15), and 0.065–2.87 (mean 0.532) μg/g, respectively. Bismuth contents were found to be greater than the limit of detection (LOD > 0.016 μg/g) in all the human hair samples collected from residents from Qinglong antimony mine, 95.5% samples from Xikuangshan mine and only 22.7% samples from Guiyang. There were no significant differences in both arsenic and antimony concentrations between hair samples from male and female individuals in the same area (P > 0.05). Arsenic and bismuth were mainly present in samples from children (5–9 years) and adults aged 41–51 years. Relatively high antimony contents (≥ 3 μg/g) were detected mainly in samples from children and adults aged ≥ 41 years. Significant correlation was found between the concentrations of arsenic and antimony in the human hair samples (r = 0.523, P < 0.05). The results indicate that arsenic and antimony in antimony mining area may significantly affect human health.
Full-text · Article · Jan 2011 · Microchemical Journal
[Show abstract][Hide abstract] ABSTRACT: To study the characteristics of antimony (Sb) bioaccumulation under high Sb background values, aquatic, amphibious and terrestrial biological samples were collected in the vicinity of the Xikuangshan (XKS) Sb mine area in China. Hydride generation-atomic fluorescence (HG-AFS) analysis showed that Sb concentrations in terrestrial invertebrates (average 30,400μgkg−1 dry wt.) were higher than those in aquatic (average 5200μgkg−1 dry wt.) and amphibian (average 2300μgkg−1 dry wt.) biological samples. Within 1km distance of the XKS Sb mine area, grasshoppers (Acrida chinensis) and earthworms (Pheretima aspergillum) had the highest Sb amounts of 17,300±3200 and 43,600±47,700μgkg−1 dry wt., respectively. No Sb biomagnifications were observed. The bioavailability of Sb was found to be lower than those of As and Hg. A preliminary conclusion is that antagonistic effects exist between Sb and Hg accumulation in biological samples from aquatic environments. Our study is the first to report such antagonistic effects between Sb and Hg. If this deduction proves to be correct, it should be taken into consideration in assessing human health risks, especially when Sb and Hg concentrations in the aquatic environments are high.
Full-text · Article · Jan 2011 · Microchemical Journal
[Show abstract][Hide abstract] ABSTRACT: The chemical modification of the alginate/chitosan/alginate (ACA) hydrogel microcapsule with methoxy poly(ethylene glycol) (MPEG) was investigated to reduce nonspecific protein adsorption and improve biocompatibility in vivo. The graft copolymer chitosan-g-MPEG (CS-g-MPEG) was synthesized, and then alginate/chitosan/alginate/CS-g-MPEG (ACAC(PEG)) multilayer hydrogel microcapsules were fabricated by the layer-by-layer (LBL) polyelectrolyte self-assembly method. A quantitative study of the modification was carried out by the gel permeation chromatography (GPC) technique, and protein adsorption on the modified microcapsules was also investigated. The results showed that the apparent graft density of the MPEG side chain on the microcapsules decreased with increases in the degree of substitution (DS) and the MPEG chain length. During the binding process, the apparent graft density of CS-g-MPEG showed rapid growth-plateau-rapid growth behavior. CS-g-MPEG was not only bound to the surface but also penetrated a certain depth into the microcapsule membranes. The copolymers that penetrated the microcapsules made a smaller contribution to protein repulsion than did the copolymers on the surfaces of the microcapsules. The protein repulsion ability decreased with the increase in DS from 7 to 29% with the same chain length of MPEG 2K. CS-g-MPEG with MPEG 2K was more effective at protein repulsion than CS-g-MPEG with MPEG 550, having a similar DS below 20%. In this study, the microcapsules modified with CS-g-MPEG2K-DS7% had the lowest IgG adsorption of 3.0 ± 0.6 μg/cm(2), a reduction of 61% compared to that on the chitosan surface.
[Show abstract][Hide abstract] ABSTRACT: Antimony (Sb) has received increasing attention recently due to its toxicity and potential human carcinogenicity. In the present work, drinking water, fish and algae samples were collected from the Xikuangshan (XKS) Sb mine area in Hunan, China. Results show that serious Sb and moderate arsenic (As) contamination is present in the aquatic environment. The average Sb concentrations in water and fish were 53.6 + or - 46.7 microg L(-1) and 218 + or - 113 microg kg(-1) dry weight, respectively. The Sb concentration in drinking water exceeded both Chinese and WHO drinking water guidelines by 13 and 3 times, respectively. Antimony and As concentrations in water varied with seasons. Fish gills exhibited the highest Sb concentrations but the extent of accumulation varied with habitat. Antimony enrichment in fish was significantly lower than that of As and Hg.
Full-text · Article · Jul 2010 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: We report the influence of surface morphology and charge of alginate/chitosan (ACA) microcapsules on both the amount of adsorbed protein and its secondary structural changes during adsorption. Variations in surface morphology and charge were controlled by varying alginate molecular weight and chitosan concentration. Plasma fibrinogen (Fgn) was chosen to model this adsorption to foreign surfaces. The surface of ACA microcapsules exhibited a granular structure after incubating calcium alginate beads with chitosan solution to form membranes. The surface roughness of ACA microcapsule membranes decreased with decreasing alginate molecular weight and chitosan concentration. Zeta potential measurements showed that there was a net negative charge on the surface of ACA microcapsules which decreased with decreasing alginate molecular weight and chitosan concentration. The increase in both surface roughness and zeta potential resulted in an increase in the amount of Fgn adsorbed. Moreover, the higher the zeta potential was, the stronger the protein-surface interaction between fibrinogen and ACA microcapsules was. More protein molecules adsorbed spread and had a greater conformational change on rougher surfaces for more surfaces being available for protein to attach.
[Show abstract][Hide abstract] ABSTRACT: The concentration levels of antimony, arsenic and mercury in human hair collected from Xikuangshan antimony mining area and Guiyang City were determined by hydride generation-atomic fluorescence spectrometry after having been digested by nitric acid and perchloric acid. The contents of Sb, As and Hg are 15.9, 4.21, 1.79 microg/g in the samples from Xikuangshan antimony mining area and 0.532, 0.280, 0.338 microg/g in the samples from Guiyang City respectively. The contents of Sb, As and Hg in human hair of Xikuangshan antimony area are much higher than those of Guiyang City. The independent-samples t-test shows that there are no marked differences in the contents of Sb and As between male and female hair samples from both Xikuangshan antimony mining area and Guiyang City (p > 0.05), while Hg contents in male hair are apparently higher than those in female hair from Guiyang City (p < or = 0.05). There is positive correlation observed between As and Sb, as well as between As and Hg, while Sb is weakly correlated with Hg (p < or = 0.01). These results show that the heavy metals (Sb, As and Hg) in antimony mining area may significantly affect human health than in the un-mining areas.
No preview · Article · Mar 2009 · Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.]
[Show abstract][Hide abstract] ABSTRACT: Alginate-chitosan-alginate (ACA) microcapsules have been developed as a device for the transplantation of living cells. However, protein adsorption onto the surface of microcapsules immediately upon their implantation decides their ultimate biocompatibility. In this work, the chemical composition of the ACA membranes was determined using X-ray photoelectron spectroscopy (XPS). The surface wettability and charge were determined by contact angle and zeta potential measurements, respectively. Then, the effects of surface wettability and charge on bovine fibrinogen (Fgn) and gamma globulin (IgG) adsorption onto ACA microcapsules were evaluated. The results showed that ACA microcapsules had a hydrophilic membrane. So, the surface wettability of ACA microcapsules had little effect on protein adsorption. There was a negative zeta potential of ACA microcapsules which varies with the viscosity or G content of alginate used, indicating a varying degree of net negatively charged groups on the surface of ACA microcapsules. The amount of adsorbed protein increased with increasing of positive charge. Furthermore, the interaction between proteins and ACA microcapsules is dominated by electrostatic repulsion at pH 7.4 and that is of electrostatic attraction at pH 6.0. This work could help to explain the bioincompatibility of ACA microcapsules and will play an important role in the optimization of the microcapsule design.
No preview · Article · Jan 2009 · Journal of Biomedical Materials Research Part A
[Show abstract][Hide abstract] ABSTRACT: To study the effect of the osmotic stress in the microenvironment on the growth and metabolism of the encapsulated cells under aerobic condition, Osmo-sensitive yeast Y02724 and high-osmotic resistant yeast Hansel were used as models to explore the growth and metabolism state of the cells cultivated inalginate-chitosan-alginate (ACA) microcapsules. The changes of the yeast cells' specific growth rate, maximum product quantity and the secretion of ethanol and glycerol were analyzed. For Y02724, the yield of ethanol was increased in the ACA microenvironment compared to suspension cultivation. For Hansel, the maximum growth speed of microencapsulated cultivation had no obvious difference compared to the suspension cultivation. Moreover, after encapsulation, the production of glycerol was decreased for both Y02724 and Hansel compared to suspension cultivation. In conclusion, osmotic stress existed in the ACA microcapsules and affected the growth and metabolism of the cells.
No preview · Article · Aug 2008 · Sheng wu gong cheng xue bao = Chinese journal of biotechnology
[Show abstract][Hide abstract] ABSTRACT: Microencapsulation technology is a convenient method to alter and regulate cell product formation. In order to probe the metabolic response of different osmo-sensitive Sacchromyces cerevisiae to ACA microcapsule, the hyper-osmo-sensitive type S. cerevisiae (Y02724) and wild type S. cerevisiae (BY4741) were encapsulated into liquid core ACA microcapsules. The behavior of cell growth, glucose consumption, ethanol production and the yields of glycerol and organic acids were determined. Free cell culture was used as control. The enzyme activities of NADP+-glutamate dehydrogenase (GDH), glutamine synthetase (GS) and glutamate synthase (GOGAT) on microencapsulation cells and free cultured cells were measured too. The results demonstrated that the growth of Y02724 in both aerobic and anaerobic conditions was seriously inhibited by ACA microcapsule, while the ethanol and acetatic acid yield of microencapsulation Y02724 in anaerobic condition were significantly higher than that of suspended cultivation. For Y02724, the microencapsulation cultivation significantly increased the GS and GOGAT activities and decreased the GDH activity in comparison with control group. ACA microcapsules did not significantly change the growth behavior and metabolic performance of BY4741, but decreased the GS activity. In conclusion, microcapsules microenvironment significantly changes the metabolism behavior of hyper-osmo-sensitive type S. cerevisiae (Y02724), but nearly had no effect on BY4741.
No preview · Article · Jun 2008 · Enzyme and Microbial Technology