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951.
Zhengzheng Zhang Hong Li Hongyan Liu Yingchen Bai Jinjuan Li Guorui Zhi Yanting Yu Wenjun Li Hao Zhang Fan Meng 《环境科学学报(英文版)》2021,33(4):363-372
The pollution characteristics of surfactant substances in fine particles (PM2.5) in spring were studied in the Beibu Gulf Region of China, 68 samples of PM2.5 were collected at Weizhou Island in Beihai City from March 12 to April 17, 2015. The Anionic Surfactant Substances (ASS) and Cationic Surfactant Substances (CSS) in the samples were analyzed using Byethyl Violet Spectrophotometry and Disulfide Blue Spectrophotometry, respectively. Combined with the data from backward trajectory simulation, the effects of air pollutants from remote transport on the pollution characteristics of surfactant substances in PM2.5 in the Beibu Gulf Region were analyzed and discussed. The results showed that the daily mean concentrations of ASS and CSS in spring in the Beibu Gulf Region were 165.20 pmol/m3 and 8.05pmol/m3, and the variation ranges were 23.21–452.55 pmol/m3 and 0.65–31.31 pmol/m3, accounting for 1.82‰ ± 1.65‰ and 0.12‰ ± 0.11‰ of the mass concentration of PM2.5, respectively. These concentrations were lower than those in comparable regions around the world. There was no clear correlation between the concentrations of ASS and CSS in PM2.5 and the mass concentrations of PM2.5. Tourism and air transport had a positive contribution on the concentrations of ASS. The concentration of surfactant substances in PM2.5 was significantly impacted by wind speed and wind direction. Atmospheric temperature, air pressure and precipitation had little effect on the concentrations of surfactant substances. Surfactant substances in PM2.5 significantly impacted visibility. Results also showed that the main sources of surfactant substances were from the southern China and Southeast Asia. 相似文献
952.
Zhonglan Yang Lingyu Bai Shiming Su Yanan Wang Cuixia Wu Xibai Zeng Benhua Sun 《环境科学学报(英文版)》2021,33(2):43-50
During the aging process, ferrihydrite was transformed into mineral mixtures composed of different proportions of ferrihydrite, goethite, lepidocrocite and hematite. Such a transformation may affect the fixed ability of arsenic. In this study, the stability of Fe-As composites formed with As(V) and the minerals aged for 0, 1, 4, 10 and 30 days of ferrihydrite were systematically examined, and the effects of molar of ratios Fe/As were also clarified using kinetic methods combined with multiple spectroscopic techniques. The results indicated that As(V) was rapidly adsorbed on minerals during the initial polymerization process, which delayed both the ferrihydrite conversion and the hematite formation. When the Fe/As molar ratio was 1.875 and 5.66, the As(V) adsorbed by ferrihydrite began to release after 6 hr and 12 hr, respectively. The corresponding release amounts of As(V) were 0.55 g/L and 0.07 g/L, and the adsorption rates were 92.43% and 97.50% at 60 days, respectively. However, the As(V) adsorbed by the transformation products aged for 30 days of ferrihydrite began to release after adsorbed 30 days. The corresponding release amounts of As(V) were 0.25 g/L and 0.03 g/L, and the adsorption rates were 84.23% and 92.18% after adsorbed 60 days, for the Fe/As=1.875 and 5.66, respectively. Overall, the combination of As(V) with ferrihydrite and aged products transformed from a thermodynamically metastable phase to a dynamically stable state within a certain duration. Moreover, the aging process of ferrihydrite reduced the sorption ability of arsenate by iron (hydr)oxide but enhanced the stability of the Fe-As composites. 相似文献
953.
Soot formation in a methane air turbulent jet diffusion flame is investigated numerically using a semi-empirical model. The temperature, density and species (the soot precursor C2H2) fields are calculated using detailed chemical kinetic mechanism based on the flamelet library approach. The influence of pressure on the soot formation and the behavior of the semi-empirical model in different flame situations are investigated. It is found that the flame shape and the flame temperature can be well predicted by the flamelet library approach. The calculated soot yield is mostly sensitive to the soot surface growth rate and the increase of pressure. The increase of pressure leads to the increase of soot surface growth rate and therefore to the increase of soot volume fraction. By adjusting a model constant in the soot surface growth rate, the soot emissions in both pressure p = 1 atm and p = 3 atm are properly simulated by the current semi-empirical soot model. 相似文献
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通过近三年实验室采用亚甲基蓝分光光度法测定硫化物校准曲线制作的一系列原始数据的收集,并通过数理统计方法对校准曲线、-余标准偏差、斜率扩展不确定度、截距扩展不确定度开展了详细讨论,得出亚甲基蓝分光光度法测定硫化物校准曲线斜率(b)参考范围为:0.019 1±0.00044,截距(a)参考值范围:0.003 3±0.005 0.此结果对实验室分析人员判定硫化物项目校准曲线制作是否合格具有一定的参考价值. 相似文献
958.
矿山开采导致大量的氟元素得到释放,进入水体造成氟污染。选取某铀尾矿库区排放水、尾矿库渗滤水及其周边浅层地下水作为研究对象,研究和分析了该铀尾矿库及其周边水系中氟的含量特征与成因。结果表明:研究区尾矿库排放水、尾矿库渗滤水和浅层地下水中氟的浓度平均值分别为30.93、21.27和1.82 mg/L。尾矿库排放水氟的含量均未达到排放要求;周边浅层地下水氟污染严重,超标率达到85.7%。总体而言,尾矿区及其周边水系中氟的含量较高,整体污染严重。而影响水系中氟的含量除人为因素外,还包括p H值、TDS以及当地气候条件等重要因素;水系中的F~-与HCO_3~-、Ca~(2+)以及其它阴、阳离子都在一定程度上呈现正负相关,表明氟的含量也可能受这些阴、阳离子的影响。 相似文献
959.
Lang Liu Yanli Wang Shiyong Du Wenjie Zhang Lujian Hou Sverre Vedal Bin Han Wen Yang Mindong Chen Zhipeng Bai 《环境科学学报(英文版)》2016,28(2):145-153
To investigate the composition and possible sources of particles, especially during heavy haze pollution, a single particle aerosol mass spectrometer (SPAMS) was deployed to measure the changes of single particle species and sizes during October of 2014, in Beijing. A total of 2,871,431 particles with both positive and negative spectra were collected and characterized in combination with the adaptive resonance theory neural network algorithm (ART-2a). Eight types of particles were classified: dust particles (dust, 8.1%), elemental carbon (EC, 29.0%), organic carbon (OC, 18.0%), EC and OC combined particles (ECOC, 9.5%), Na-K containing particles (NaK, 7.9%), K-containing particles (K, 21.8%), organic nitrogen and potassium containing particles (KCN, 2.3%), and metal-containing particles (metal, 3.6%). Three haze pollution events (P1, P2, P3) and one clean period (clean) were analyzed, based on the mass and number concentration of PM2.5 and the back trajectory results from the hybrid single particle Lagrangian integrated trajectory model (Hysplit-4 model). Results showed that EC, OC and K were the major components of single particles during the three haze pollution periods, which showed clearly increased ratios compared with those in the clean period. Results from the mixing state of secondary species of different types of particles showed that sulfate and nitrate were more readily mixed with carbon-containing particles during haze pollution episodes than in clean periods. 相似文献
960.
Fabrication and performance of PET mesh enhanced cellulose acetate membranes for forward osmosis 总被引:1,自引:0,他引:1
Polyethylene terephthalate mesh(PET) enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematically evaluated including the concentration and temperature of the casting polymer solution and the temperature and time of the evaporation, coagulation and annealing processes. The water permeability and reverse salt flux were measured in forward osmosis(FO) mode for determination of the optimal membrane fabrication conditions. The optimal FO membrane shows a typical asymmetric sandwich structure with a mean thickness of about 148.2 μm. The performance of the optimal FO membrane was tested using 0.2 mol/L Na Cl as the feed solution and 1.5 mol/L glucose as the draw solution. The membrane displayed a water flux of 3.47 L/(m2·hr) and salt rejection of95.48% in FO mode. While in pressure retarded osmosis(PRO) mode, the water flux was4.74 L/(m2·hr) and salt rejection 96.03%. The high ratio of water flux in FO mode to that in PRO mode indicates that the fabricated membrane has a lower degree of internal concentration polarization than comparable membranes. 相似文献