Risk control and assessment of sulfide-rich sediment remediation by controlled-release calcium nitrate.

Nitrate stimulation is widely used in sediment remediation to eliminate sulfides, degrade organic pollutants and immobilize phosphorus. However, the environmental risks of nitrate escape and the subsequent release of pollutants (e.g. nitrite, ammonium and trace metals) to water bodies during its application has received less attention. In this study, controlled-release nitrate pellets (SedCaN pellets) were manufactured and applied at different sediment depths to examine their effectiveness in controlling the risk of nitrate escape and subsequent pollutant release. The germination of submerged plant was also analyzed to assess the ecological risks associated with the remediated sediment. The results showed that the SedCaN pellets slowly released calcium nitrate, which led to denitrifying sulfide oxidation, organic matter degradation and the immobilization of phosphorus as a calcium-bound species. Gas production by denitrification increased the sediment porosity (0.3-2.2%) and led to the concomitant release of nitrite, ammonium, and heavy metals, creating secondary risks. Application of the SedCaN pellets at depth decreased the nitrate escape and the secondary risks, presumably by means of a capping effect of the upper sediment. The release of nitrate, ammonium, Ni and Cu were partially limited by 91.6%, 19.0%, 61.6% and 57.4% when SedCaN pellets were incorporated into deeper sediments (7-9 cm). Moreover, the range of sulfide oxidation extended to the upper and lower sediments in the profile (column), while the sulfide oxidation efficiency reached 85.9-95.0%. Finally, increased germination of Bacopa monnieri (20.0-26%) demonstrated that in comparison to reference materials the ecological risks of the treated sediments was reduced and the habitat function of sediment was restored after nitrate-stimulating remediation. The results of this study provide valuable guidelines for nitrate-stimulating remediation of sulfide-rich (black-odor) sediments.

Different effects of low- and high-dose waterborne zinc on Zn accumulation, ROS levels, oxidative damage and antioxidant responses in the liver of large yellow croaker Pseudosciaena crocea.

The aim of the present study was to assess survival rate, Zn accumulation, reactive oxygen species (ROS) levels, oxidative damage and antioxidant responses after Zn exposure (2 and 8 mg L-1 Zn) at different exposure times (6, 12, 24, 48 and 96 h) in the liver of large yellow croaker. Survival rate was reduced at 96 h, and hepatic Zn content increased during 24-96 by 8 mg L-1 Zn. In the 2 mg L-1 Zn group, no fish died and the increase in Zn content merely occurred at 96 h. Exposure to 8 mg L-1 Zn induced accumulation of ROS, lipid peroxidation and protein carbonylation during the late stage of exposure. In contrast, exposure to 2 mg L-1 Zn did not result in oxidative damage, which may result from the up-regulation of antioxidant defenses. Although exposure to 8 mg L-1 Zn increased activities and mRNA levels of antioxidant enzymes during the early stage of exposure, including Cu/Zn-SOD, Mn-SOD, CAT, GPx and GR, the activities of these enzymes except Cu/Zn-SOD were inhibited at 96 h. Furthermore, a sharp increase in Nrf2 expression was observed in fish exposed to 8 mg L-1 at 6 and 12 h, and 2 mg L-1 at 12 h and 24 h, suggesting that Nrf2 was required for the protracted induction of these genes. The late increase in Keap1 expression may support its role in switching off the Nrf2 response. In conclusion, the present study demonstrated different effects of low- and high-dose waterborne Zn on antioxidant responses, which could contribute to the understanding of antioxidant and toxic roles of zinc on a molecular level.

Molecular characterization and expression analysis of AMPK α subunit isoform genes from Scophthalmus maximus responding to salinity stress.

AMP-activated protein kinase (AMPK) is a highly conserved and multi-functional protein kinase that plays important roles in both intracellular energy balance and cellular stress response. In the present study, molecular characterization, tissue distribution and gene expression levels of the AMPK α1 and α2 genes from turbot (Scophthalmus maximus) under salinity stress are described. The complete coding regions of the AMPK α1 and α2 genes were isolated from turbot through degenerate primers in combination with RACE using muscle cDNA. The complete coding regions of AMPK α1 (1722 bp) and α2 (1674 bp) encoded 573 and 557 amino acids peptides, respectively. Multiple alignments, structural analysis and phylogenetic tree construction indicated that S. maximus AMPK α1 and α2 shared a high amino acid identity with other species, especially fish. AMPK α1 and α2 genes could be detected in all tested tissues, indicating that they are constitutively expressed. Salinity challenges significantly altered the gene expression levels of AMPK α1 and α2 mRNA in a salinity- and time-dependent manners in S. maximus gill tissues, suggesting that AMPK α1 and α2 played important roles in mediating the salinity stress in S. maximus. The expression levels of AMPK α1 and α2 mRNA were a positive correlation with gill Na+, K+-ATPase activities. These findings will aid our understanding of the molecular mechanism of juvenile turbot in response to environmental salinity changes.

Performance of a combined system of biotrickling filter and photocatalytic reactor in treating waste gases from a paint-manufacturing plant.

A pilot-scale biotrickling filter (BTF) was established in treating the waste gases that are intermittently produced from an automobile paint-manufacturing workshop. Results showed that the BTF required longer time to adapt to the aromatic compounds. The removal efficiencies (REs) for all aliphatic compounds reached more than 95% on day 80. Aromatic compounds were not easily removed by the BTF. The REs obtained by the BTF for toluene, ethylbenzene, m-xylene, o-xylene and p-xylene on day 80 were 72.7%, 77.2%, 71.9%, 74.8% and 60.0%, respectively. A maximum elimination capacity (EC) of 13.8 g-C m(-3) h(-1) of the BTF was achieved at an inlet loading rate of 19.4 g-C m(-3) h(-1) with an RE of 72%. Glucose addition promoted the biomass accumulation despite the fact that temporal decrease of REs for aromatic compounds occurred. When the inlet loading rates exceed 11.1 g-C m(-3) h(-1), the REs of the aromatic compounds decreased by 10% to 15%. This negative effect of shock loads on the performance of the BTF can be attenuated by the pre-treatment of the photocatalytic reactor. Nearly all components were removed by the combined system with REs of 99%.

Novel roles of ginsenoside Rg3 in apoptosis through downregulation of epidermal growth factor receptor.

Ginsenoside Rg3 (Rg3), a pharmacologically active compound from red ginseng, has been reported to induce cell death in various cancer cell lines, although the specific mechanisms have not been well established. In the present study, Rg3 treatment to A549 human lung adenocarcinoma led to cell death via not only apoptotic pathways but also the downregulation of epidermal growth factor receptor (EGFR). We used cross-linker and cell enzyme-linked immunosorbent assays to show that Rg3 inhibited EGFR dimerization by EGF stimulation and caused EGFR internalization from the cell membrane. Among several important phosphorylation sites in cytoplasmic EGFR, Rg3 increased the phosphorylation of tyrosine 1045 (pY1045) and serine 1046/1047 (pS1046/1047) for EGFR degradation and coincidently, attenuated pY1173 and pY1068 for mitogen-activated protein kinase activity. These effects were amplified under EGF-pretreated Rg3 stimulation. In vivo experiments showed that the average volume of the tumors treated with 30 mg/kg of Rg3 was significantly decreased by 40% compared with the control. Through immunohistochemistry, we detected the fragmentation of DNA, the accumulation of Rg3, and the reduction of EGFR expression in the Rg3-treated groups. Here, we provide the first description of the roles of Rg3 in the reduction of cell surface EGFR, the attenuation of EGFR signal transduction, and the eventual activation of apoptosis in A549 human lung adenocarcinoma.

Characterization of the enhancement of zero valent iron on microbial azo reduction.

BACKGROUND: The microbial method for the treatment of azo dye is promising, but the reduction of azo dye is the rate-limiting step. Zero valent iron (Fe(0)) can enhance microbial azo reduction, but the interactions between microbes and Fe(0) and the potential mechanisms of enhancement remain unclear. Here, Shewanella decolorationis S12, a typical azo-reducing bacterium, was used to characterize the enhancement of Fe(0) on microbial decolorization. RESULTS: The results indicated that anaerobic iron corrosion was a key inorganic chemical process for the enhancement of Fe(0) on microbial azo reduction, in which OH(-), H2, and Fe(2+) were produced. Once Fe(0) was added to the microbial azo reduction system, the proper pH for microbial azo reduction was maintained by OH(-), and H2 served as the favored electron donor for azo respiration. Subsequently, the bacterial biomass yield and viability significantly increased. Following the corrosion of Fe(0), nanometer-scale Fe precipitates were adsorbed onto cell surfaces and even accumulated inside cells as observed by transmission electron microscope energy dispersive spectroscopy (TEM-EDS). CONCLUSIONS: A conceptual model for Fe(0)-assisted azo dye reduction by strain S12 was established to explain the interactions between microbes and Fe(0) and the potential mechanisms of enhancement. This model indicates that the enhancement of microbial azo reduction in the presence of Fe(0) is mainly due to the stimulation of microbial growth and activity by supplementation with elemental iron and H2 as an additional electron donor. This study has expanded our knowledge of the enhancement of microbial azo reduction by Fe(0) and laid a foundation for the development of Fe(0)-microbial integrated azo dye wastewater treatment technology.

Emission of odorous volatile organic compounds from a municipal manure treatment plant and their removal using a biotrickling filter.

Odorous volatile organic compounds (VOCs) from municipal manure treatment facilities are considered as a major nuisance issue for operators and nearby residents. In this study, up to 71 odorous VOCs were detected by gas chromatography-mass spectrometry at the manure treatment plant. These compounds can be classified into five different categories, including alkanes, olefins, aromatics, volatile organosulphur compounds and terpenes. Toluene, dimethyl disulphide, dimethyl sulphide, xylene and ethylbenzene were the five most abundant pollutants. A pilot-scale biotrickling filter (BTF) was employed to treat the complex odorous gases. Correlation analysis showed that the removal efficiency (RE) of the BTF was related with the molecular weight and chemical structure of contaminants. Higher than 85% of REs could be reached for aromatic, terpenes and most alkanes compounds after 180 days of operation. Comparatively, most olefins and partial alkanes compounds with a molecular weight lower than 70 were not removed easily. The REs of these compounds ranged from 0% to 94%, and the average removal efficiency (RE) was only about 33.3%.

Separation of triterpenoid saponins from the root of Bupleurum falcatum by counter current chromatography: the relationship between the partition coefficients and solvent system composition.

A separation method using counter current chromatography coupled with an evaporative light-scattering detection system was developed to purify five triterpenoid saponins from the roots of Bupleurum falcatum. The methanol extract was loaded onto a Diaion® HP20 column and fractionated by a methanol and water gradient elution. The saikosaponin-enriched fraction was obtained by elution with 100% methanol. The two-phase solvent systems used for separation were composed of chloroform/methanol/isopropanol/water at a volume ratio of 60:60:1:60 and 6:6:1:6. The relationship between the isopropanol ratio of each phase and the partition coefficients of the target compounds was investigated by calculating partition coefficient by high-performance liquid chromatography and measuring the accurate composition of each phase by (1) H NMR spectroscopy. Each fraction obtained was collected and dried, which yielded the following five saikosaponins from 700 mg of injected sample: saikosaponin B1 (8.7 mg), saikosaponin A (86 mg), saikosaponin B3 (17 mg), saikosaponin B2 (41 mg), and saikosaponin C (33 mg). Saikosaponin A showed the most potent cytotoxicity against human cancer cells (gastric cancer, AGS cells; breast cancer, MCF-7 cells; and hepatoma, HepG2 cells) after 24 h. The IC50 values for the above three cell types were 34.6, 33.3, and 23.4 µmol/L, respectively.

Elevated nitrate enriches microbial functional genes for potential bioremediation of complexly contaminated sediments.

Nitrate is an important nutrient and electron acceptor for microorganisms, having a key role in nitrogen (N) cycling and electron transfer in anoxic sediments. High-nitrate inputs into sediments could have a significant effect on N cycling and its associated microbial processes. However, few studies have been focused on the effect of nitrate addition on the functional diversity, composition, structure and dynamics of sediment microbial communities in contaminated aquatic ecosystems with persistent organic pollutants (POPs). Here we analyzed sediment microbial communities from a field-scale in situ bioremediation site, a creek in Pearl River Delta containing a variety of contaminants including polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs), before and after nitrate injection using a comprehensive functional gene array (GeoChip 4.0). Our results showed that the sediment microbial community functional composition and structure were markedly altered, and that functional genes involved in N-, carbon (C)-, sulfur (S)-and phosphorus (P)- cycling processes were highly enriched after nitrate injection, especially those microorganisms with diverse metabolic capabilities, leading to potential in situ bioremediation of the contaminated sediment, such as PBDE and PAH reduction/degradation. This study provides new insights into our understanding of sediment microbial community responses to nitrate addition, suggesting that indigenous microorganisms could be successfully stimulated for in situ bioremediation of POPs in contaminated sediments with nitrate addition.

Antitumor activity of jujuboside B and the underlying mechanism via induction of apoptosis and autophagy.

Jujuboside B (1) is one of the saponins isolated from the seeds of Zizyphus jujuba var. spinosa, which are used as a well-known traditional medicine for the treatment of insomnia and anxiety in East Asian countries. This is the first study to investigate the antitumor mechanism of 1 in vivo and in vitro. The results showed that 1 induced apoptosis and autophagy in AGS and HCT 116 human cancer cells and also effectively suppressed tumor growth in a nude mouse xenograft model bearing HCT 116 cells. The apoptosis-inducing effect of 1 was characterized by annexin V/propidium iodide staining, sub-G1 phase increase, and caspase-3 activation. Mechanistic studies showed that 1-induced apoptosis is associated with the extrinsic pathway through an increase in FasL and caspase-8 activation. Moreover, 1 activated p38/c-Jun N-terminal kinase (JNK), and the extrinsic pathway-mediated apoptosis was attenuated by both SB202190 (a p38 inhibitor) and SP600125 (a JNK inhibitor). The autophagy-inducing effect was indicated by the formation of cytoplasmic vacuoles and microtubule-associated protein 1 light chain-3 II (LC3-II) conversion. The autophagy inhibitor bafilomycin A1 (BaF) decreased 1-induced cell viability and increased pp38, pJNK, FasL, caspase-8 activation, and caspase-3 activation. Taken together, these results demonstrate that 1 induced protective autophagy to retard extrinsic pathway-mediated apoptosis.

Akebia saponin PA induces autophagic and apoptotic cell death in AGS human gastric cancer cells.

In this study, we investigated the anticancer mechanism of akebia saponin PA (AS), a natural product isolated from Dipsacus asperoides in human gastric cancer cell lines. It was shown that AS-induced cell death is caused by autophagy and apoptosis in AGS cells. The apoptosis-inducing effect of AS was characterized by annexin V/propidium (PI) staining, increase of sub-G1 phase and caspase-3 activation, while the autophagy-inducing effect was indicated by the formation of cytoplasmic vacuoles and microtubule-associated protein 1 light chain-3 II (LC3-II) conversion. The autophagy inhibitor bafilomycin A1 (BaF1) decreased AS-induced cell death and caspase-3 activation, but caspase-3 inhibitor Ac-DEVD-CHO did not affect LC3-II accumulation or AS-induced cell viability, suggesting that AS induces autophagic cell death and autophagy contributes to caspase-3-dependent apoptosis. Furthermore, AS activated p38/c-Jun N-terminal kinase (JNK), which could be inhibited by BaF1, and caspase-3 activation was attenuated by both SB202190 and SP600125, indicating that AS-induced autophagy promotes mitogen-activated protein kinases (MAPKs)-mediated apoptosis. Taken together, these results demonstrate that AS induces autophagic and apoptotic cell death and autophagy plays the main role in akebia saponin PA-induced cell death.

Responses of microbial community functional structures to pilot-scale uranium in situ bioremediation.

A pilot-scale field test system with an inner loop nested within an outer loop was constructed for in situ U(VI) bioremediation at a US Department of Energy site, Oak Ridge, TN. The outer loop was used for hydrological protection of the inner loop where ethanol was injected for biostimulation of microorganisms for U(VI) reduction/immobilization. After 2 years of biostimulation with ethanol, U(VI) levels were reduced to below drinking water standard (<30 microg l(-1)) in the inner loop monitoring wells. To elucidate the microbial community structure and functions under in situ uranium bioremediation conditions, we used a comprehensive functional gene array (GeoChip) to examine the microbial functional gene composition of the sediment samples collected from both inner and outer loop wells. Our study results showed that distinct microbial communities were established in the inner loop wells. Also, higher microbial functional gene number, diversity and abundance were observed in the inner loop wells than the outer loop wells. In addition, metal-reducing bacteria, such as Desulfovibrio, Geobacter, Anaeromyxobacter and Shewanella, and other bacteria, for example, Rhodopseudomonas and Pseudomonas, are highly abundant in the inner loop wells. Finally, the richness and abundance of microbial functional genes were highly correlated with the mean travel time of groundwater from the inner loop injection well, pH and sulfate concentration in groundwater. These results suggest that the indigenous microbial communities can be successfully stimulated for U bioremediation in the groundwater ecosystem, and their structure and performance can be manipulated or optimized by adjusting geochemical and hydrological conditions.

[Determination of 8 trace elements in mantle muscle and cuttlebone of Sepiella maindroni by ICP-MS using microwave digestion for sample preparation].

An inductively coupled plasma mass spectrometry (ICP-MS) for determination of the contents of 8 trace elements in mantle muscle and cuttlebone of Sepiella maindroni after microwave digestion of the sample has been developed. Satisfactory linearity of working curves for the 8 elements was obtained, giving all their correlation coefficients over 0.997 3. The precision of measurement ranges from 2.4% to 8.7% in terms of relative standard deviation. The recoveries and the limits of detection are in the range of 96.5%-106.3% and 0.002-0.032 microg x L(-1), respectively. It was indicated that the proposed method had the advantages of simplicity, speediness and sensitivity. The results showed that the mantle muscle and cuttlebone of Sepiella maindroni contained rich trace elements Zn and Cu, but the contents of Cd and As are higher than the limits of Chinese Pharmacopoeia, Green Trade Standard for Importing and Exporting Medicinal Plant and Preparation and U.S. Food and Drug Standard. Furthermore, our study provides new scientific foundation for the quality control, culture, general application, resource utilization and exporting of Sepiella maindroni.

Determination of trace selenium by solid substrate-room temperature phosphorescence enhancing method based on potassium chlorate oxidizing phenyl hydrazine-1,2-dihydroxynaphthalene-3,6-disulfonic acid system.

A new method for the determination of trace selenium based on solid substrate-room temperature phosphorimetry (SS-RTP) has been established. This method was based on the fact that in HCl-KCl buffer solution, potassium chlorate could oxidize phenyl hydrazine to form chloridize diazo-ion after being heated at 100 degrees C for 20 min, and then the diazo-ion reacted with 1,2-dihydroxynaphthalene-3,6-disulfonic acid to form red azo-compound which could emit strong room temperature phosphorescence (RTP) signal on filter paper. Selenium could catalyze potassium chlorate oxidizing the reaction between phenyl hydrazine and 1,2-dihydroxynaphthalene-3,6-disulfonic acid, which caused the sharp enhancement of SS-RTP. Under the optimum condition, the relationship between the phosphorescence emission intensity (DeltaIp) and the content of selenium obeyed Beer's law when the concentration of selenium is within the range of 1.60-320 fg spot-1 (or 0.0040-0.80 ng ml-1 with a sample volume of 0.4 microl). The regression equation of working curve can be expressed as DeltaIp=13.12+0.4839CSe(IV) (fg spot-1) (n=6), with correlation coefficient r=0.9991 and a detection limit of 0.28 fg spot-1 (corresponding to a concentration range of 7.0x10(-13) g ml-1 Se(IV), n=11). After 11-fold measurement, R.S.D. were 2.8 and 3.5% for the samples containing 0.0040 and 0.80 ng ml-1 of Se(IV), respectively. This accurate and sensitive method with good repeatability has been successfully applied to the determination of trace selenium in Chinese wolfberry and egg yolk with satisfactory results. The mechanism of the enhancement of phosphorescence was also discussed.