Search

ABSTRACTNitrogen stripping plays a vital role during the sulfate-rich wastewater treatment process by sulfate-reducing bacteria (SRB). However, the interaction between nitrogen stripping, sulfate reduction capacity, S2–concentration, and microbial community structure is rarely studied. Here, two anaerobic systems were conducted to analyze these interactions simultaneously. Results showed that the toxic products (H2S) were stripped by nitrogen at first. Then, the increased relative abundance of fermentative bacteria accelerated the carbon sources conversion, and Desulfovibrio, Dethiosulfovibrio, and Sulfurospirillumfacilitated the sulfate reduction after nitrogen stripping. Finally, the produced S2−concentration was increased by 12%, and the sulfate reduction rate was increased by 9.2% compared to that without nitrogen stripping.

ABSTRACTThe indium-bearing zinc ferrite (IBZF) was synthesised, used as a research object, and mechanically activated with the planetary ball mill. Sulphur dioxide was introduced as reductant and leachant to create a reducing atmosphere and react with water to provide H+. The reductive leaching kinetics of activated IBZF samples was studied with sulphur dioxide as leachant and reductant. The results showed that the mechanical activation could change the physicochemical properties of IBZF significantly, thus improving its reactivity. The unreacted shrinking core model was an excellent fit for the kinetics of zinc and indium leaching. This indicated that the leaching process was controlled by surface chemical reaction and the activation energy was 62.57 and 57.30 kJ·mol−1. After the mechanical activation for 60 min, the activation energies of zinc and indium leaching decreased to 40.66 and 44.26 kJ·mol−1, respectively. In addition, the reaction order for the partial pressure of sulphur dioxide for zinc and indium leaching decreased from 1.28 to 1.25 and from 1.30 to 1.28, respectively.

As one of the most sensitive regions to global climate change, alpine tundra in many places around the world has been undergoing dramatic changes in vegetation communities over the past few decades. Herbaceous plant species in the Changbai Mountains area have significantly expanded into tundra shrub communities over the past 30 yr. Soil microbial communities, enzyme activities, and soil nutrients are intertwined with this expansion process. In order to understand the responses of the soil microbial communities to such an expansion, we analyzed soil microbial community structures and enzyme activities in shrub tundra as well as areas with three different levels of herbaceous plant expansion. Our investigation was based on phospholipid fatty acid (PLFA) analysis and 96-well microtiter plates. The results showed that herbs have expanded greatly in the tundra, and they have become the dominant species in herbaceous plant expansion areas. There were differences for community composition and appearance among the shrub tundra and the mild expansion, moderate expansion, and severe expansion areas. Except for soil organic matter, soil nutrients were increased in herbaceous plant expansion areas, and the total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), and available phosphorus (AP) were greatest in moderate expansion areas (MOE), while soil organic matter levels were highest in the non-expanded areas (CK). The total soil PLFAs in the three levels of herbaceous plant expansion areas were significantly higher than those in the non-expanded areas, and total soil PLFAs were highest in the moderately expanded area and lowest in the severely expanded area (SEE). Bacteria increased significantly more than fungi and actinomycetes with herbaceous plant expansion. Soil hydrolase activities (β-1,4-glucosidase (βG) activity, β-1, 4-N-acetylglucosaminidase (NAG) activity, and acid phosphatase (aP) activity) were highest in MOE and lowest in the CK treatment. Soil oxidase activities (polyphenol oxidase (PPO) activities and peroxidase (PER) activities) were also highest in MOE, but they were lowest in the SEE treatment. The variations in total soil PLFAs with herbaceous plant expansion were mostly correlated with soil organic matter and available phosphorus concentrations, while soil enzyme activities were mostly correlated with the total soil nitrogen concentration. Our results suggest that herbaceous plant expansion increase the total soil PLFAs and soil enzyme activities and improved soil nutrients. However, soil microorganisms, enzyme activity, and nutrients responded differently to levels of herbaceous plant expansion. The soil conditions in mild and moderate expansion areas are more favorable than those in severe expansion areas.

Vegetation in high altitude areas normally exhibits the strongest response to global warming. We investigated the tundra vegetation on the Changbai Mountains and revealed the similarities and differences between the north and the southwest slopes of the Changbai Mountains in response to global warming. Our results were as follows: 1) The average temperatures in the growing season have increased from 1981 to 2015, the climate tendency rate was 0.38°C/10yr, and there was no obvious change in precipitation observed. 2) The tundra vegetation of the Changbai Mountains has changed significantly over the last 30 years. Specifically, herbaceous plants have invaded into the tundra zone, and the proportion of herbaceous plants was larger than that of shrubs. Shrub tundra was transforming into shrub-grass tundra. 3) The tundra vegetation in the north and southwest slopes of the Changbai Mountains responded differently to global warming. The southwest slope showed a significantly higher degree of invasion from herbaceous plants and exhibited greater vegetation change than the north slope. 4) The species diversity of plant communities on the tundra zone of the north slope changed unimodally with altitude, while that on the tundra zone of the southwest slope decreased monotonously with altitude. Differences in the degree of invasion from herbaceous plants resulted in differences in species diversity patterns between the north and southwest slopes. Differences in local microclimate, plant community successional stage and soil fertility resulted in differential responses of tundra vegetation to global warming.

A simple and sensitive high-performance liquid chromatographic procedure for the determination of the trans isomer of glimepiride is reported. Chromatography accomplished direct separation of the cis and trans isomers of glimepiride on a Dikmonsil C18 (250×4.6 mm, 5 μm) column with a mobile phase consisting of methanol-acetonitrile-NH4Ac buffer solution (1.5 mol L^–1, pH = 4.5) (1.1 : 1.3 : 1.0, v/v) at a flow rate 0.5 mL min^–1. The resolution (RS) was 1.73 with a retention time of 24.885 and 23.018 min for the cis and the trans isomer, respectively. A standard linear calibration curve was established for the trans isomer of glimepiride over the range of 4.95–198.00 μg mL^–1 with a correlation coefficient of 0.99997. This method has been successfully used to analyze four different kinds of glimepiride product.

A simple and sensitive high‐performance liquid chromatographic procedure for the determination of the transisomer of glimepiride is reported. Chromatography accomplished direct separation of the cisand transisomers of glimepiride on a Dikmonsil C18 (250×4.6 mm, 5 μm) column with a mobile phase consisting of methanol‐acetonitrile‐NH4Ac buffer solution (1.5 mol L–1, pH = 4.5) (1.1 : 1.3 : 1.0, v/v) at a flow rate 0.5 mL min–1. The resolution (RS) was 1.73 with a retention time of 24.885 and 23.018 min for the cisand the transisomer, respectively. A standard linear calibration curve was established for the transisomer of glimepiride over the range of 4.95–198.00 μg mL–1with a correlation coefficient of 0.99997. This method has been successfully used to analyze four different kinds of glimepiride product.