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651.
极端干旱区咸水灌溉人工防护林土壤可溶性碳的垂直分布及其影响因素 总被引:1,自引:1,他引:0
可溶性碳(DC)是土壤中最活跃的碳组分,植被恢复与重建加速了干旱荒漠区的碳循环过程.研究咸水灌溉下沙漠人工防护林地土壤剖面DC的分布,可为干旱荒漠区人工林的管理和开发利用提供理论支撑和决策依据.本研究选取塔克拉玛干沙漠公路沿线5个不同矿化度咸水滴灌林地作为研究样地,流沙地为对照(CK),分析并讨论了0~1 m剖面土壤可溶性有机碳(SDOC)和可溶性无机碳(SDIC)的垂直分布特征及其与各因子间的相关关系.结果表明,CK与2.82 g·L-1矿化度滴灌处理SDOC、SDIC呈"I"型分布,其分布满足线性函数关系,其他各样地SDOC和SDIC均呈"Γ"型分布,分布满足幂函数关系;所有处理表层SDOC、SDIC波动能力及贡献度均高于下层土壤,且SDOC波动及贡献度均大于SDIC, 2.82 g·L-1之外的各林地SDOC平均含量是SDIC的2~4倍;2.82 g·L-1样地SDOC平均含量低于CK,其他各样地SDOC是CK的3~5倍,各样地SDIC含量较CK增加了15.0%~57.9%;矿化度高于2.82 g·L-1... 相似文献
652.
Yongjiao Xiong Baoqiang Wu Xiangfeng Huang Chenlu Li Bin Lu Jia Liu Lijun Lu Shiyang Li Kaiming Peng 《环境科学学报(英文版)》2021,33(7):173-183
Magnetic particles were coupled with a flocculant to enhance the demulsification and separation of waste cutting emulsions. The optimal magnetic particle size and critical magnetic field conditions were investigated to achieve large-scale engineering application of magnetic demulsification separation for waste cutting emulsion treatment. The micro-scale magnetic particles were found to show comparable effects to nano-scale magnetic particles on enhancing the demulsification and separation of cutting emulsions, which are beneficial for broadening the selectivity of low-cost magnetic particles. The critical magnetic separation region was determined to be an area 40 mm from the magnetic field source. Compared to the flocculant demulsification, the magnetic demulsification separation exhibited a significant advantage in accelerating flocs–water separation by decreasing the separation time of flocs from 180–240 min to less than 15 min, compressing the flocs by reducing the floc volume ratio from 60%–90% to lower than 20%, and showing excellent adaptability to the variable properties of waste cutting emulsions. Coupled with the design of the magnetic disk separator, continuous demulsification separation of the waste cutting emulsion was achieved at 1.0 t/hr for at least 10 hr to obtain clear effluent with 81% chemical oxygen demand removal and 89% turbidity reduction. This study demonstrates the feasibility of applying magnetic demulsification separation to large-scale continuous treatment of waste emulsion. Moreover, it addresses the flocs–water separation problems that occur in practical flocculant demulsification engineering applications. 相似文献
653.
This article considers the target level of safety (TLS) for Chinese airspace. If collision risk is lower than TLS, we can say the separation minima meet the safety requirements, so the TLS is the safety limit on the flight operation. But there are no regulations on TLS in China by now, hence, it is necessary to judge whether it is fair to apply the TLS proposed by ICAO to evaluating air traffic safety in China.The accidents data of more than 50 years are collected, and we apply the trend extrapolation to predicting the safety level in the future so as to resolve the TLS problem. The resulted showed the safety level in the period from 2010 to 2020 is very close to TLS established by ICAO. The results show the safety level of collision risk in China has reached the international level and it is rational to use TLS of ICAO to assess collision risk. 相似文献
654.
Jiayou Ji Huizhi Xiong Zhenni Zhu Liang Li Yineng Huang Xianghua Yu 《Journal of Polymers and the Environment》2018,26(5):1979-1985
Three-dimensional polypyrrole/chitosan nanocomposite monoliths are fabricated by polymerization of pyrrole in chitosan aqueous solution. The static polymerization of pyrrole monomer and the cross-linking of chitosan by glutaraldehyde occur simultaneously, resulting in the self-assembly of polypyrrole/chitosan nanocomposite aerogel monolith. The addition of methyl orange and glutaraldehyde and the static reaction play key roles in the formation of the self-standing aerogel monolith. The as-prepared monolith with larger specific surface area exhibits much better adsorption capability for Cr(VI) removal in comparison with that prepared without the addition of glutaraldehyde. The adsorption process and adsorption isotherms are found to well follow the pseudo-second-order and Langmuir models, respectively. Furthermore, this polypyrrole/chitosan nanocomposite monolith is stable and recyclable. About 73.5% of the initial adsorption capability is kept after eight adsorption–desorption cycles. The polypyrrole/chitosan nanocomposite monolith can be a promising candidate for the efficient removal of Cr(VI). 相似文献
655.
Journal of Polymers and the Environment - The present investigation aimed at developing core–shell structured partially etherified fenugreek seed mucilage (EFSM)-sodium alginate (SA) based... 相似文献
656.
为了适应钝感弹药发展的需求,利用冲击波汇聚技术和起爆理论,研究了环形、锥环形两种新型传爆药装药结构。试验表明,环形传爆药较圆柱形传爆药可减少药量约15% ,锥环形传爆药较圆柱形传爆药可减少药量约26% 。研究结果对于减少武器爆炸序列中敏感元件——传爆药的使用数量,进而提高武器系统使用安全性具有重要意义 相似文献
657.
硝酸铵气溶胶挥发动力学 总被引:1,自引:0,他引:1
研究了单分散NH4NO3干气溶胶在流动反应器内的挥发动力学,结果表明,挥发反应符合零级反应,凝聚反应符合二级反应,NH4NO3气溶胶计算粒径为0.65μm,计算数浓度为80-120个/cm^3时, 相似文献
658.
不同来源的海州香薷和野胡萝卜的铜抗性及铜积累差异 总被引:2,自引:0,他引:2
以来自矿区(铜绿山和赤马山铜矿)和非矿区(红安、武汉严西湖)的海州香薷和野胡萝卜种群为对象,通过土培实验,研究了2种植物的铜抗性及铜吸收积累差异.结果显示,来自矿区的海州香薷和野胡萝卜种群的铜抗性都明显高于非矿区种群,但2种植物种群的铜吸收积累特征明显不同:海州香薷植物吸收的Cu主要集中在根中,但矿区种群吸收积累的铜量明显低于非矿区种群;而野胡萝卜吸收的Cu主要集中在地上部分(地上部分的Cu富集量是根的1.5倍),但积累的铜量在矿区和非矿区种群间没有明显的差异.因此,来自矿区的海州香薷可能进化为铜避性对策,而野胡萝卜的铜抗性与其吸收积累的总量没有明显的关系,但有很好的向地上运输能力. 相似文献
659.
660.