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21.
甲基绿-高碘酸钾催化光度法测定痕量铂 总被引:5,自引:0,他引:5
利用痕量铂 (IV)在稀磷酸介质中对高碘酸钾氧化甲基绿褪色反应的催化作用 ,建立了测定痕量铂 (IV)的催化动力学光度法。方法检出限为 3.4× 10 - 1 0 g/mL ,线性范围为 0~ 2 4μg/L。用于催化剂及矿石中铂的测定 ,结果满意。 相似文献
22.
Kaul Gena Hitoshi Chiba Katsuo Kase Kazuo Nakashima Daizo Ishiyama 《Resource Geology》2013,63(4):360-370
A sulfide chimney ore sampled from the flank of the active Tiger vent area in the Yonaguni Knoll IV hydrothermal field, south Okinawa trough, consists of anhydrite, pyrite, sphalerite, galena, chalcopyrite and bismuthinite. Electron microprobe analysis indicates that the chalcopyrite contains up to 2.4 wt% Sn, whereas bismuthinite contains up to 1.7 wt% Pt, 0.8 wt% Cu and 0.5 wt% Fe. The Sn‐rich chalcopyrite and Pt–Cu–Fe‐bearing bismuthinite are the first reported occurrence of such minerals in an active submarine hydrothermal system. The results confirm that Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn4+Fe2+ for Fe3+Fe3+, whereas Pt, Cu and Fe enter the bismuthinite structure as a solid solution during rapid nucleation. The fluid inclusions homogenization temperatures in anhydrite (220–310°C) and measured end‐member temperature of the vent fluids on‐site (325°C) indicate that Sn‐bearing chalcopyrite and Pt–Cu–Fe‐bearing bismuthinite express the original composition of the minerals that precipitated as metastable phases at a temperature above 300°C. The result observed in this study implies that sulfides in ancient volcanogenic massive sulfide deposits have similar trace element distribution during nucleation but it is remobilised during diagenesis, metamorphism or supergene enrichment processes. 相似文献
23.
Sang-Han Lee Pavel P. Povinec Janine Gastaud Beniamino Oregioni Laurent Coppola Catherine Jeandel 《Journal of Oceanography》2009,65(3):397-406
Anthropogenic 90Sr, 239,240Pu and 241Am were used as tracers of water mass circulation in the Crozet Basin of the South Indian Ocean, represented by three main
water fronts—Agulhas (AF), Subtropical (STF) and Subantarctic (SAF). Higher 90Sr concentrations observed north of 43°S were due to the influence of AF and STF, which are associated with the south branch
of the Subtropical gyre, which acts as a reservoir of radionuclides transported from the North to the South Indian Ocean.
On the other hand, the region south of 43°S has been influenced by SAF, bringing to the Crozet Basin Antarctic waters with
lower radionuclide concentrations. The 238Pu/239,240Pu activity ratios observed in water and zooplankton samples indicated that, even 35 years after the injection of 238Pu to the Indian Ocean from the burn-up of the SNAP-9A satellite, the increased levels of 238Pu in surface water and zooplankton are still well visible. The radionuclide concentrations in seawater and their availability
to zooplankton are responsible for the observed 210Po, 239,240Pu and 241Am levels in zooplankton. 相似文献
24.
25.
Punit Kumar Mudgal Anil Kumar Sharma C. D. Mishra S. P. Bansal K. S. Gupta 《Journal of Atmospheric Chemistry》2008,61(1):31-55
This is the first study, which shows both NH3 and NH4+ to inhibit the autoxidation of aqueous SO2 in the pH range 7.0–8.5. The rate of the autoxidation, R
aut
, in both buffered and unbuffered media at a fixed pH is in conformity with the rate law:
where R
0
is rate in the absence of the inhibitors, B is a pH dependent empirical constant and [Inh]T is the analytical concentration of NH3 or NH4+. Both ammonia and ammonium ions appear to inhibit the autoxidation either by scavenging SO4− radicals or by forming less-reactive /unreactive Co(II)-NH3 complexes or both. The atmospheric relevance of the inhibition by ammonia and ammonium ions is discussed. 相似文献
26.
In this study, the results of four different field experiments concerning the speciation of iron and the concentrations of some other chemical compounds in cloudwater samples are compared to one-another. Hydrogen peroxide concentrations were higher during campaigns, conducted at sites not much influenced by anthropogenic emissions as compared to those conducted at more polluted areas. In contrast, percentages of S(IV) in the cloudwater were lowest at the rural sites and highest at the sites polluted by human activities, indicating a consumption of hydrogen peroxide in the oxidation reaction with S(IV). The concentration of dissolved iron was observed to correlate with the percentage of S(IV), which may be an essential point for the reductive dissolution of oxidic iron compounds of the aerosol particles. As far as the speciation of the dissolved iron is concerned, it became obvious that the percentage of Fe(III) is anticorrelated to the concentration of dissolved iron. This clearly shows the important effect of the chemical and/or photo reductive ways of dissolving the iron(III)-compounds from the aerosol particles. However, a correlation between the pH-value and hydrogen peroxide was observed. 相似文献
27.
以唐山响嘡局部场地影响台阵3号测井场地(Ⅱ类场地)作为实验场地,验证用FLAC~(3D)软件方法进行土层地震反应计算的可行性。以天津塘沽某IV类场地为例,在不同地震动强度输入条件下分别采用FLAC~(3D)软件方法和等效线性化程序方法计算该场地地表地震动峰值和反应谱。计算结果表明:在输入地震动强度较小时,两种方法计算得到的结果差别不大;在输入地震动强度较大时,FLAC~(3D)方法克服了等效线性化方法低估地表地震反应(高频部分)和高估土体的非线性所造成的地表反应谱特征周期偏大问题。FLAC~(3D)方法计算得到的结果可能更符合工程实际。 相似文献
28.
Irena Grgić Andreja Dovžan Gorazd Berčič Vida Hudnik 《Journal of Atmospheric Chemistry》1998,29(3):315-337
Laboratory experiments were conducted with real atmospheric aerosol particles as well as with synthetic solutions under dark conditions, to simulate some of the chemical features of aerosols. In solutions obtained by the leaching of aerosols (size range >D
ae: 0.4–1.6 m) that contained sufficient amounts of transition metal ions (e.g. Fe) and organic species (e.g. oxalate), S(IV) oxidation rates were significantly lower than those expected from the Fe-catalyzed S(IV) autoxidation in Milli-Q water. The results suggest that oxalate is responsible for much of the observed inhibition. Acetate and formate also inhibit the reaction, but to a much lesser extent. Oxalate has a strong inhibiting effect on the Fe-catalyzed S(IV) autoxidation at all investigated pH values (2.8, 3.7 and 4.5). It was established that Fe(III)-oxalato complexes affect the redox cycling of Fe(II)/Fe(III) and that the observed decrease of the reaction rate is caused by the reduced amount of catalytically active Fe(III) due to the complexation with oxalate. For the system Fe-S(IV)-O2-oxalate at initial pH 3.7 the reaction rate was calculated using exponential simplification to account for oxalate influence on the amount of free Fe(III) by the following equation:–rS(IV) = k · [S(IV)] · [Fe(III))] · e
-b·[Ox] 相似文献
29.
Thorium(IV) biosorption is investigated by citric acid treated mangrove endophytic fungus Fussarium sp. #ZZF51 (CA-ZZF51) from South China Sea. The biosorption process was optimized at pH 4.5, equilibrium time 90 min, initial thorium(IV) concentration 50 mg L−1 and adsorbent dose 0.6 g L−1 with 90.87% of removal efficiency and 75.47 mg g−1 of adsorption capacity, which is obviously greater than that (11.35 mg g−1) of the untreated fungus Fussarium sp. #ZZF51 for thorium(IV) biosorption under the condition of optimization. The experimental data are analyzed by using isotherm and kinetic models. Kinetic data follow the pseudo-second-order model and equilibrium data agree very well with the Langmuir model. In addition, FTIR analysis indicates that hydroxyl, amino, and carbonyl groups act as the important roles in the adsorption process. 相似文献
30.
ZHANG Yaoyao CHU Fengyou LI Zhenggang DONG Yanhui LONG Jiangping WANG Hao ZHU Jihao LIU Jiqiang 《《地质学报》英文版》2020,94(1):126-140
The Okinawa Trough is characterized by enrichment of Ag in hydrothermal precipitates; however, the distribution of this enrichment remains poorly constrained. This study presents the results of a field-emission scanning electron microscopy and electron-microprobe analysis based mineralogical and geochemical investigation of the spatial distribution of Ag within Ag-rich sulfide samples from the Okinawa Trough. The tetrahedrite, covellite, and galena in these samples contain high concentrations of... 相似文献