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191.
192.
2016年9月利用多波束测深仪调查了张家洲河段河床微地貌的高分辨率形态与分布特征,结合1998年和2013年水下地形资料,分析了三峡截流以来该河段河槽的冲淤变化与演变趋势。结果表明:(1)张家洲河段整体呈冲刷状态,净冲刷量17.2×10.6 m3。其中,张家洲南水道是强冲刷区,最大冲刷深度约9 m;(2)河槽表层沉积物中值粒径为149.1~226.3 μm,与历史资料相比呈粗化趋势;(3)张家洲河段约82.9%的主航道发育了沙波,约14.0%的主航道发育了冲刷坑与冲刷槽,平床地形仅占3.1%。流域来沙量减少是张家洲河段整体冲刷的主要原因,而河流控制工程稳定了河势,迫使水流归槽,加剧了张家洲南水道的冲刷。随着流域来沙量持续减少,张家洲南水道主航道有可能进一步冲刷 相似文献
193.
He Genhe Wang Xiaodong Liu Xu Xiao Xiaoyu Huang Shoucheng Wu Jichun 《Russian Journal of Ecology》2018,49(6):524-533
Russian Journal of Ecology - The present study characterized the nutrients availability of three rare earth tailings deserted in different time stages in Southern Jiangxi of China, and revealed the... 相似文献
194.
Qing Zhao Kebin He Kenneth A. Rahn Yongliang Ma Fumo Yang Fengkui Duan 《Atmospheric environment (Oxford, England : 1994)》2010,44(21-22):2615-2624
Depletion of Si in transported dust has been recognized for many years. It can be used to distinguish between transported and local dust in cities, although it rarely has been. Here we use the variations of the Si/Al ratio in 15 months of continuous PM2.5 samples at Beijing (northern China) and Chongqing (southwestern China) to reveal the seasonal patterns of their dust sources. For both cities, peaks of concentration for Si and Al in PM2.5 corresponded with minima of Si/Al, and could often be linked to pulsed air flow from deserts to the northwest. With significant depletion (up to 80%) and homogeneous distribution at urban and rural sites, Si/Al showed a clear seasonal evolution, which decreased from spring to summer, increased from fall to winter, and collapsed during Chinese Spring Festival, indicating the dominance of transported dust, local fugitive dust and firework influence, respectively. The low ratios implied that desert dust is a common source during spring at Chongqing, whereas its presence during cold season at Beijing was also more frequent than expected. Failing to recognize the depletion of Si may lead to an overestimate of desert dust by 15%–65% when using the average abundance of Al in crust (6%–8%), as in previous studies. The difference in Si/Al ratio between local and transported dust implies that >60% of the dust at Beijing came from outside the city during the springs of 2004–2006. This result can help resolve the contradictory findings on this topic that have been presented earlier. 相似文献
195.
Jinzhu Ma Yongchun Liu Hong He 《Atmospheric environment (Oxford, England : 1994)》2010,44(35):4446-4453
To further understand the role of substrates on the heterogeneous reactions of polycyclic aromatic hydrocarbons, the reactions of ozone with anthracene adsorbed on different mineral oxides (SiO2, α-Al2O3 and α-Fe2O3) and on Teflon disc were investigated in dark at 20 °C. No reaction between ozone and anthracene on Teflon disc was observed when the ozone concentration was ~1.18 × 1014 molecules cm?3. The reactions on mineral oxides exhibited pseudo-first-order kinetics for anthracene loss, and the pseudo-first-order rate constant (k1,obs) displayed a Langmuir–Hinshelwood dependence on the gas-phase ozone concentration. The adsorption equilibrium constants for ozone (KO3) on SiO2-1, SiO2-2, α-Al2O3 and α-Fe2O3 were (0.81 ± 0.26) × 10?15 cm3, (2.83 ± 1.17) × 10?15 cm3, (2.48 ± 0.77) × 10?15 cm3 and (1.66 ± 0.45) × 10?15 cm3, respectively; and the maximum pseudo-first-order rate constant (k1,max) on these oxides were (0.385 ± 0.058) s?1, (0.101 ± 0.0138) s?1, (0.0676 ± 0.0086) s?1 and (0.0457 ± 0.004) s?1, respectively. Anthraquinone was identified as the main surface product of anthracene reacted with ozone. Comparison with previous research and the results obtained in this study suggest that the reactivity of anthracene with ozone and the lifetimes of anthracene adsorbed on mineral dust in the atmosphere are determined by the nature of the substrate. 相似文献
196.
197.
废弃轮胎制备中孔炭吸附材料工艺及性能研究 总被引:1,自引:0,他引:1
为了解决废弃轮胎造成的资源浪费和环境污染的问题,对以废弃轮胎橡胶为碳的前驱体原料,制备具有高吸附性能中孔炭材料工艺进行了系统的研究。通过XRD、扫描电镜以及比表面积分析,对制备的中孔炭微观结构和性能进行表征,讨论了炭化温度、碱炭比,以及活化温度和活化时间等工艺条件对制备中孔炭的产率、结构和性能的影响。结果表明,通过改变工艺条件制备的中孔炭的孔径分布可以在2~80 nm范围内进行调控。在500℃炭化温度,碱炭比为4∶1,900℃活化1 h的工艺条件下,制备的中孔炭的比表面积为473 m2/g,对甲基橙的最大吸附量达到254 mg/g。 相似文献
198.
199.
Yu-Yang Long Li-Fang Hu Jing Wang Cheng-Ran Fang Ruo He Dong-Sheng Shen 《Environmental science and pollution research international》2010,17(9):1539-1546
Purpose
To protect the environmental quality of soil, groundwater, and surface water near the landfill site, it is necessary to make an accurate assessment of the heavy metal mobility. This study aims to present the bio-immobilization behavior of heavy metals in landfill and provide some reference suggestion for the manipulation of heavy metal pollution control after closure. 相似文献200.
Ge Yuan Chen Chengrong Xu Zhihong Eldridge Simon M. Chan Kwong Yin He Yan He Ji-Zheng 《Environmental science and pollution research international》2010,17(3):807-815