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141.
浙东沿海上白垩统小雄组的建立 总被引:1,自引:0,他引:1
浙东临海、三门东部的小雄盆地,发育一套中酸偏碱性的火山岩。长期以来,将其称为塘上组。详细的地质调查研究表明;这套火山岩与以天台盆地为代表的塘上组,在火山岩岩石组合、层序、古生物化石组合和同位素年龄等均不相同。火山岩是超覆于永康群馆头组、朝川组和小平田组之上,成岩时代在85—98Ma,产晚白垩世翼龙和鸟类化石,是晚白世的喷发一沉积产物。为一独立的具有自身特色的岩石地层单位,故建立新的岩石地层单位一小雄组。 相似文献
142.
Pagrosomus major larvae were to the water-soluble fraction of hydrocarbon in No.0 diesel oil(corresponding to No.2 fuel oil) at concentration of 0,0.17,1.22 and 8.82mg/L for up to 15 days.Larvae were sampled on days 9 and 15 of the experiment.Supernatants of viscera tissue extractions were assayed for biochemical response in terms of oxidative stress-superoxide dismutase(SOD),activity of selenium-dependant glutathione peroxidase(Se-GPx) and catalase(Ca),and the concentration of reduced glutathione(CSH).On day 9 of exposure ,statistically significant dose-related increases in Se-GPx and SOD activity,and GSH concentration were observed in all cases except for Se-GPx activity under the highest dosage of hydrocarbon.However,on day 15 of exposure, a similar dose-related in all cases except for Se-GPx activity under the highest dosage of hydrocarbon.However,on day 15 of exposure, a similar dose-related response was only observed for Se-GPx activity.GSH concentration decreased and SOD activity showed no statistical difference as compared to controls.However, a significant decrease in compared to day 9 Se-GPx activity and GSH concentration, in contrast to increase SOD activity at day 15 as indicates an accelerated accumulation of H2O2 and potential oxidative damage under long term exposure of larvae to hydrocarbons.No statistical changes were observed in Ca activity throughout the experiment, possibly owing to the high efficiency of Se-GPx.A recovery experiment was performed on indicating that the response of antioxidants measured tending to returm to return to their control levels.These results prove the function of the antioxidant defense system of the larvae to the water-soluble fraction of hydrocarbons in No.0 diesel oil. 相似文献
143.
The CuO-MoO3/gamma-Al2O3 catalyst, confirmed previously as having good activity in the catalytic incineration of (CH3)2S2, was employed as the principal catalyst in this study. With the aim of improving catalyst activity and resistance to deactivation by sulfur compounds, a promoter was added either before adding the precursors of Cu and Mo or together with Cu and Mo onto the gamma-Al2O3. Promoters included transition metals and elements from groups IA-VIIA in the chemical periodic table. Experimental results reveal Cr2O3 as the most effective promoter, with an optimal composition of 5 wt.% Cu, 6 wt.% Mo and 4 wt.% Cr (designated as Cu(5)-Mo(6)-Cr(4)/gamma-Al2O3). Knowing that higher acidity can improve activity, we further investigated the effect of acid treatment on the performance of the Cu(5)-Mo(6)-Cr(4)/gamma-Al2O3 catalyst. Experimental results indicate the H2SO4-treated catalyst (Cu(5)-Mo(6)-Cr(4)/sulfated-gamma-Al2O3) has a better activity and durability. A study for finding an appropriate rate expression for the catalytic incineration of (CH3)2S2 by Cu(5)-Mo(6)-Cr(4)/sulfated-gamma-Al2O3 was carried out in a differential reactor. The results show that the Mars-Van Krevelen model is applicable to this destructive oxidation reaction. Results additionally reveal that competitive adsorption of CH4 reduces conversion of (CH3)2S2. 相似文献
144.
Shuting Luo Xiaodong Wu Baofang Jin Shuang Liu Rui Ran Zhichun Si Duan Weng 《环境科学学报(英文版)》2020,32(8):64-71
Pt/Al2O3 catalysts with mean Pt particle size ranged from 2.7 to 7.1 nm were synthesized by chemical reduction method, and the sulfated counterparts were prepared by impregnation of sulfuric acid. The turnover frequency of platinum for soot oxidation under loose contact conditions in a feed flow containing NO and O2 are positively correlated with the size of platinum. The sulfated Pt/Al2O3 exhibits higher catalytic activity for soot oxidation in the presence of NO despite their reduced ability for NO2 production. Such a contradiction is more significant for those catalysts with smaller platinum particles. Herein, the catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), inductive coupled plasma (ICP) emission spectrometry, CO chemisorption, thermogravimetric analysis (TGA), NH3 temperature-programmed desorption (NH3-TPD), NO temperature-programmed oxidation (TPO) and NOx temperature-programmed desorption (TPD). Possible effect of Pt particle size for the catalytic oxidation of soot in the presence of NO was presented based primarily on the promoted NO2 transfer efficiency onto the soot pushed by the acidic catalysts. 相似文献
145.
Daojun Zhang Ziran M Baodong Wang Tao Zhu Duan Weng Xiaodong Wu Hongyan Wang Ge Li Jiali Zhou 《环境科学学报(英文版)》2020,32(2):145-154
A series of vanadium based catalysts(VxMn(4-x)Mo3Ce3/Ti) with different vanadium(x wt.%) and manganese((4-x) wt.%) contents have been prepared by the wet impregnation method and investigated for selective catalytic reduction(SCR) of NO_x by NH_3 in the presence of 8 vol.% H_2O and 500 ppm V SO_2.The physicochemical characteristics of the catalysts were thoroughly characterized.The SCR of NO_x by NH_3(NH_3-SCR) activity, especially the low-temperature activity, significantly increased with increasing V_2O_5 content in the catalyst until the V_2O_5 content reached 1.5 wt.%, which corresponds well with the redox properties of the catalyst.All of the metal oxides were well dispersed and strongly interacted with each other on the catalyst surface.V mainly exists in the V~(5+)state in the catalysts.The strong synergistic effect between the vanadium and cerium species led to formation of more Ce~(3+)species, and that between the vanadium and manganese species contributed to formation of more manganese species with low valences.All of the catalysts exhibited strong acidity, while the redox properties determined the NH_3-SCR activity, especially the low-temperature activity.H_2O and SO_2 had severe inhibiting effects on the activity of V1.5Mn2.5Mo3Ce3/Ti.However, good H_2O and SO_2 resistance and high NO_x conversion by V1.5Mn2.5Mo3Ce3/Ti could be achieved in the presence of SO_2 and almost no decline was observed in a long-term test at 275℃ for 168 hr in the presence of SO_2 and H_2O, which can be attributed to the sulfate species formed on the catalyst surface. 相似文献
146.
A series of H-SAPO-34 zeolites were synthesized by a hydrothermal method in fluoride media. The as-synthesized H-SAPO-34 zeolites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 physisorption, temperature-programmed desorption of NH3 (NH3-TPD) and nuclear magnetic resonance (NMR) measurements. The results showed that a certain concentration of F− anions promoted the nucleation and crystallization of H-SAPO-34. The H-SAPO-34 synthesized in the fluoride media showed high crystallinity, uniform particle size distribution, large specific surface area and pore volume, and enhanced acidity. Therefore, Cu/SAPO-34 based on the fluoride-assisted zeolite showed a broadened temperature window for the selective catalytic reduction of NO by NH3 (NH3-SCR) reaction due to the enhanced acidity of the zeolite and the improved dispersion of copper species. 相似文献
147.
148.
A pot experiment was conducted to explore a more effective approach to enhancing vegetable uptake of soil iodine, with the
ultimate goal of using agricultural fortification as a measure to prevent iodine deficiency disorders in local communities.
Two types of iodine fertilizers were added separately to pot soil samples at various dosages. The fortified soil in each of
the flower pots was seeded with one of four test crops (pakchoi, celery, pepper, and radish) in an effort to examine the effect
of vegetable cultivation. The fate and residual levels of the exogenous iodine in the fortified soil samples were then monitored
and quantified. The data showed that the soil iodine contents decreased with time (and hence with plant growth as well). At
the second cutting, iodine from the inorganic form (KI) as the exogenous source was reduced to approximately 50% (41.6–61.0%)
of the applied dose, whereas that in soil fortified with the seaweed fertilizer was down to approximately 60% (53.9–71.5%).
The abilities of the edible portion of the four vegetables in accumulating the soil iodine were as follows: pakchoi > celery > radish > pepper.
On the whole, iodine residues were found less in soil cultivated with vegetables. Vegetable cultivation appeared to have enhanced
the soil content of the water-soluble form of iodine somewhat, especially in soil fortified with the inorganic forms. There
also appeared to be a significant negative correlation between the residual iodine and its dissolution rate in soil. Overall,
the results of the present study pointed toward the direction that the seaweed fertilizer tends to be a (more) preferred source
of agricultural fortification in promoting human iodine nutrition. 相似文献
149.
Rice farming sustainability assessment in Bangladesh 总被引:1,自引:0,他引:1
Farming sustainability is primordial to long-term socioeconomic development. This study assesses rice farming sustainability in Bangladesh by developing a composite indicator (CI) under the four pillars of sustainability and examines the main determining factors. The assemblage of top-down and bottom-up approaches were applied to generate an essential set of indicators and data were collected through a household survey from 15 villages of three major rice growing ecosystems. The results revealed that less than half of the rice growers were sustainable in terms of economical viability, ecological benefits, and quality of life. By category, Boro rice farming was found to be the most sustainable, followed by Aman and Aus rice farming. Human capital development, increasing land productivity, use of resource conserving practices and technologies, and information availability and accessibility were the main factors promoting rice farming sustainability. The findings indicated that the construction of CI by employing several methodologies such as normalisation provide straightforward and clear-cut policy inputs. The major policy implications that emerged from the findings of the study are outlined to actualise rice farming sustainability, which contributes to sustainable development in Bangladesh. 相似文献
150.