TiO2/活性炭催化剂对4-CP的吸附和光催化活性

采用常压金属有机物化学气相沉积技术在活性炭表面沉积构成纳米TiO2催化剂,XRD分析表明,沉积在活性炭表面的TiO2为锐钛矿晶型.TEM分析表明负载量为8%(wt)时,TiO2颗粒的粒径为10-20nm;载体负载前后BET面积仅改变了6%,表明负载TiO2后对活性炭的结构影响不大.利用Langmuir-Hinshelwood动力学模型探讨了TiO2/活性炭催化剂对4-CP的吸附行为和光催化活性之间的关系,求出4-CP降解反应速率常数Kr,在紫外光照条件下催化剂对4-CP的吸附明显增强.     

Use of beryllium-7 to document soil redistribution following forest harvest operations

Rapid and reliable methods for documenting soil erosion associated with forest harvest operations are needed to support the development of best management practices for soil and water conservation. To address this need, the potential for using 7Be measurements to estimate patterns and amounts of soil redistribution associated with individual post-harvest events was explored. The 7Be technique, which was originally developed for use on agricultural land, was employed to estimate soil redistribution associated with a period of heavy rainfall within a harvested forest area located in the Lake Region of Chile (39 degrees 44'7' S, 73 degrees 10'39' W; 22% slope; and mean annual rainfall 2300 mm yr(-1)). The results provided by the 7Be technique were validated against direct measurements of soil gain or loss during the same period obtained using erosion pins. The information produced by the two approaches was similar. The results of this study demonstrate the potential for using 7Be measurements to document event-based erosion in recently harvested forest areas.     

Determination of microbiological contamination,antibacterial and antioxidant activities of natural plant hazelnut (Corylus avellana L.) pollen

The aim of our study is to determine microbial contamination, antibacterial and antioxidant activities of 14 pollen samples of Corylus avellana collected from different locations in Slovakia. Microbiological analysis was carried out in two steps: microbiological assays and studies of antibacterial activity of pollen extracts. The antimicrobial properties of pollen extracts were carried out with the disc-diffusion method. Methanol (70%), ethanol (70%) and distilled water were used for pollen extracts. Five strains of bacteria such as gram-negative (Salmonella enterica subsp. enterica CCM 3807, Escherichia coli CCM 2024, and Yersinia enterocolitica CCM 5671) and gram-positive (Staphylococcus aureus CCM 2461 and Bacillus thuringiensis CCM 19T) were tested. Antioxidant activity of pollen extracts was determined by the DPPH method. Bacterial analysis includes the determination of the total bacterial count ranged from 4.08 to 4.61 log CFU g^?1, mesophilic aerobic bacteria ranged from 3.40 to 4.89 log CFU g^?1, mesophilic anaerobic bacteria ranged from 3.20 to 4.52 log CFU g^?1, coliform bacteria ranged from 3.30 to 4.55 log CFU g^?1, yeasts and filamentous fungi ranged from 3.00 to 3.56 log CFU g^?1. Microscopic filamentous fungi Aspergillus spp., Alternaria spp., Penicillium spp., Cladosporium spp., Rhizopus spp., and Paecylomyces spp. were isolated from hazelnut pollen. Yersinia enterocolitica was the most sensitive strain among ethanolic and methanolic pollen hazelnut extracts. Staphylococcus aureus was the most sensitive strain against aqueous hazelnut pollen extracts. We determined the following sensitivity against ethanol pollen extracts respectively: Yersinia enterocolitica?>?Salmonella enterica?>?Staphylococcus aureus?>?Bacillus thuringiensis?>?Escherichia coli. Methanol pollen extracts had shown following sensitivity: Yersinia enterocolitica?>?Salmonella enterica?>?Escherichia coli?>?Staphylococcus aureus?>?Bacillus thuringiensis. Aqueous extracts had shown the following sensitivity: Staphylococcus aureus?>?Salmonella enterica?>?Escherichia coli?>?Bacillus thuringiensis?>?Yersinia enterocolitica. Hazelnut pollen extracts have over 82% antioxidant capacity in samples from non-urban zones. An elevated level of antioxidant potential in the pollen is determined by its biological properties conditioned by biologically active substances. DPPH method allowed characterizing pollen as a source of antioxidants.     

Abundance and removal of antibiotic resistance genes (ARGs) in the rearing environments of intensive shrimp aquaculture in South China

Although research regarding antibiotic resistance genes (ARGs) in aquaculture environments has gained increasing scientific interest, further studies are required to understand the abundances and removal mechanisms of ARGs during the entire rearing period of shrimp aquaculture. Thus, in this study, abundances, distributions and removal rates of ARGs in different environmental compartments of intensive shrimp farms in South China were investigated during the entire rearing period. The results indicated that sul1 and cmlA were the predominant ARGs in the water and sediment samples. Additionally, the total abundance of ARGs was higher in shrimp pond water than in the source water and farm effluent. Moreover, sediment samples indicated significantly higher ARG abundances than water samples from the shrimp ponds (P?<?0.05). Environmental factors were found to significantly affect the distribution of ARGs in shrimp rearing environments. Furthermore, stable ponds aided the removal of ARGs from shrimp pond water. This study accounted for temporal variations in ARG abundances as well as removal of ARGs in different environmental compartments during the entire shrimp rearing period. However, additional research is required to optimize the water treatment process for removal of ARGs from the aquaculture.     

Study on the denitrification performance of FexLayOz/activated coke for NH3-SCR and the effect of CO escaped from activated coke at mid-high temperature on catalytic activity

Currently, activated coke is widely used in the removal of multiple pollutants from industrial flue gas. In this paper, a series of novel Fe_xLa_yO_z/AC catalysts was prepared by the incipient wetness impregnation for NH₃-SCR denitrification reaction. The introduction of Fe-La bimetal oxides significantly improved the denitrification performance of activated coke at mid-high temperature, and 4% Fe_0.3La_0.7O_1.5/AC exhibited a superior NO_x conversion efficiency of 90.1% at 400 °C. The catalysts were further characterized by BET, SEM, XRD, Raman, EPR, XPS, FTIR, NH₃-TPD, H₂-TPR, et al., whose results showed that the perovskite-type oxide of LaFeO₃ and oxygen vacancies were produced on the catalysts’ surfaces during roasting. Fe-La doping enhanced the amount of acid sites (mainly Lewis and other stronger acid sites) and the content of multifarious oxygen species, which were beneficial for NO_x removal at mid-high temperature. Moreover, it was investigated that the effect of released CO from activated coke at mid-high temperature on the NO_x removal through the lifetime test, in which it was found that a large amount of CO produced by pyrolysis of activated coke could promote the NO_x removal, and long-term escaping of CO on the activated coke carrier did not have a significant negative impact on catalytic performance. The results of the TG-IR test showed that volatile matter is released from the activated coke while TG results showed that the weight loss rate of 4% Fe_0.3La_0.7O_1.5/AC only was 0.0015~0.007%/min at 300–400 °C. Hence, 4% Fe_0.3La_0.7O_1.5/AC had excellent thermal stability and denitrification performance to be continuously used at mid-high temperature. Finally, the mechanisms were proposed on the basis of experiments and characterization results.

     

Microplastic distribution in surface sediments along the Spanish Mediterranean continental shelf

Environmental Science and Pollution Research - Microplastics (MPs) are widely recognised as a contaminant of emerging concern in the marine environment. This work provides original data of the...     

Ovariectomy predisposes female rats to fine particulate matter exposure’s effects by altering metabolic,oxidative, pro-inflammatory,and heat-shock protein levels

Environmental Science and Pollution Research - The reduction of estrogen levels, as a result of menopause, is associated with the development of metabolic diseases caused by alterations in...     

微波消解-流动注射分光光度法测定总氮和总磷

以碱性过硫酸钾溶液为消解液,采用微波消解-流动注射分光光度法测定水中总氮和总磷。在碱性过硫酸钾溶液中氢氧化钠质量浓度为9.6g/L、微波功率为320W、消解管长度为16m的条件下,总氮和总磷的检出限分别为0.040m g/L和0.020mg/L,线性范围分别为0.040～3.500mg/L和0.020～2.500mg/L,相对标准偏差分别为1.6%和1.0%。微波消解-流动注射分光光度法应用于河水、湖水、化工废水等实际水样中总氮和总磷的测定,加标回收率分别为95.7%～98.1%和97.2%～102.2%。     

两种表面活性剂对剩余污泥产酸影响的比较研究

在批式反应器中研究了常温下2种(两性和阳离子)表面活性剂对剩余污泥产酸的影响,结果表明,2种表面活性剂均能较大幅度地提高剩余污泥生产有机酸的产量.在污泥发酵的第4天,0.1g·g-1(表面活性剂与污泥干重比,下同)的两性和阳离子表面活性剂可分别使剩余污泥生产有机酸的浓度达到226.4和861.4 mg·L-1(以COD计,下同),而空白试验中生成的有机酸浓度仅为3.2 mg·L-1.同时,剩余污泥的有机酸产量随表面活性剂加入量的增加而增加.当表面活性剂的加入量低于0.2 g·g-1时,用两性表面活性剂处理的剩余污泥中有机酸浓度仅为用阳离子表面活性剂处理的剩余污泥中有机酸浓度的50%;当表面活性剂的加入量增至0.3 g·g-1时,两者的有机酸最大产量接近.此外,表面活性剂的种类和加入量对有机酸的组成分布也有一定的影响.     

直链烷基苯磺酸盐促进剩余污泥产生短链脂肪酸的研究

采用批试试验的方法研究了十二烷基苯磺酸钠(C12-LAS)对剩余污泥在厌氧发酵过程中产生的短链脂肪酸(SCFAs)的影响.结果表明,C12-LAS的投加极大地提高了剩余污泥厌氧发酵过程中的SCFAs产量.当C12-LAS加入量低于0.1g·g-1时,SCFAs产量随着C12-LAS加入量的增加而增加,然而,当C12-LAS加入量高于0.1g·g-1时,SCFAs产量反而有所降低.从污泥产酸量以及经济成本考虑,C12-LAS的最佳投加量为0.02g·g-1,此时剩余污泥的SCFAs最大产量出现在第6天.进一步的研究表明,C12-LAS不仅促使大量的碳水化合物和蛋白质脱离污泥颗粒并溶解到液相中,而且抑制了产甲烷菌的活性.尽管剩余污泥经历着酸化过程,但由于其释放出大量的NH4 -N,污泥在整个厌氧发酵过程中的pH值逐渐升高.