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排序方式: 共有43条查询结果,搜索用时 46 毫秒
21.
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
22.
23.
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
24.
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
25.
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
26.
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.
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
29.
ICP-AES 法测定地质样品中微量锆、 铪的研究 总被引:2,自引:0,他引:2
摘 要 在2%酒石酸介质中用阳离子交换树脂吸附干扰元素以 ICP-AES 法分别在
343∙823nm 和264∙141nm 直接测定地质样品中的微量锆和铪。锆的检出限为0∙5×10
-6 铪
为0∙4×10
-6 。此方法简单、快速应用于地球化学标准样品中锆和铪的分析取得了满意
的结果。 相似文献
30.
Comparison of radar and gauge precipitation data in watershed models across varying spatial and temporal scales
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Katie Price S. Thomas Purucker Stephen R. Kraemer Justin E. Babendreier Chris D. Knightes 《水文研究》2014,28(9):3505-3520
Precipitation is a key control on watershed hydrologic modelling output, with errors in rainfall propagating through subsequent stages of water quantity and quality analysis. Most watershed models incorporate precipitation data from rain gauges; higher‐resolution data sources are available, but they are associated with greater computational requirements and expertise. Here, we investigate whether the Multisensor Precipitation Estimator (MPE or Stage IV Next‐Generation Radar) data improve the accuracy of streamflow simulations using the Soil and Water Assessment Tool (SWAT), compared with rain gauge data. Simulated flows from 2002 to 2010 at five timesteps were compared with observed flows for four nested subwatersheds of the Neuse River basin in North Carolina (21‐, 203‐, 2979‐, and 10 100‐km2 watershed area), using a multi‐objective function, informal likelihood‐weighted calibration approach. Across watersheds and timesteps, total gauge precipitation was greater than radar precipitation, but radar data showed a conditional bias of higher rainfall estimates during large events (>25–50 mm/day). Model parameterization differed between calibrations with the two datasets, despite the fact that all watershed characteristics were the same across simulation scenarios. This underscores the importance of linking calibration parameters to realistic processes. SWAT simulations with both datasets underestimated median and low flows, whereas radar‐based simulations were more accurate than gauge‐based simulations for high flows. At coarser timesteps, differences were less pronounced. Our results suggest that modelling efforts in watersheds with poor rain gauge coverage can be improved with MPE radar data, especially at short timesteps. Published 2013. This article is a U.S. Government work and is in the public domain in the USA. 相似文献