Phytoremediation of Cadmium-Contaminated Soils by Rorippa globosa Using Two-Phase Planting (5 pp)

Background Phytoextraction of contaminated soils by heavy metals can provide a great promise of commercial development. Although there are more than 400 species of hyperaccumulators found in the world, phytoremediation technology is rarely applied in field practice for remedying contaminated soils, partially due to low biomass and long growth duration for most of discovered hyperaccumulating plants. In order to enhance the metal-removing efficiency in a year, the two-phase planting countermeasure of phytoextraction by harvesting anthesis biomass was investigated on the basis of the newly found Cd-hyperaccumulator Rorippa globosa (Turcz.) Thell. with 107.0 and 150.1 mg/kg of the Cd accumulation in stems and leaves, respectively, when soil Cd added was concentrated to 25.0 mg/kg. Methods The field pot-culture experiment was used to observe the distribution property of R. globosa aboveground biomass and to examine characteristics of accumulating Cd by the plant at different growth stages. The concentration of Cd in plants and soils was determined using atomic absorption spectrophotometry (AAS). Results and Discussion The results indicated that the total dry stem and leaf biomass of R. globosa harvested at the flowering phase was up to 92.3% of that at its full maturity and the concentration of Cd in stems and leaves harvested at the flowering phase was up to 73.8% and 87.7% of that at the mature phase, respectively. The Cd-removing ratio by shoots of R. globosa harvested at the flowering phase was up to 71.4% of that at the mature phase. It was also found, by observing the growth duration of R. globosa, that the frostless period at the experiment site was twice as long as the growth time from the seedling-transplanted phase to the flowering phase of the hyperaccumulator. Conclusion R. globosa could be transplanted into contaminated soils twice in one year by harvesting the hyperaccumulator at its flowering phase based on climatic conditions of the site and traits of the plant growth. In this sense, the extraction efficiency of Cd in shoots of R. globosa increased 42.8% compared to that of at its single maturity when the plant was transplanted into contaminated soils after it had been harvested at its flowering phase and the plant accumulated Cd from soil at the same extraction ratio at its second flowering phase. Thus, the method of anthesis biomass regulation by the two-phase planting is very significant to increase the Cd-removing efficiency by phytoremediation used in practice over the course of a year. Recommendation and Outlook As for some hyperaccumulators that the growth duration from the seedling-transplanted phase to the flowering phase are short and the concentrations of heavy metals accumulated in their shoots at the flowering phase are high, the efficiency of phytoremediation can greatly be improved using the method of the two-phase planting.     

连续起伏管道投产过程中的气相运移研究*

为应对山区液体管道在投产过程中可能出现的气阻、超压问题,从气相运移角度出发,建立液顶气模型,研究在1个U型单元内积气形成、压缩和破碎的全过程,在此基础上,提出连接各个U型单元的气相的传递函数,探讨背压累积因素下,连续起伏管道投产过程中各个U型管段的积气情况和压力的变化,进行动态的建模和计算。以国内某原油管道的现场投产数据与模型结果进行比对。结果表明:可以更加准确地预测山区液体管道投产过程中的气相传递和压力变化过程,能为未来连续起伏大落差液体管道投产的安全稳定运行提供理论指导和技术支持。     

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尾砂胶结充填体是非线性力学介质,其变形是能量耗散的复杂过程,必须研究其内在变形规律,才能正确预测采矿过程中充填体的稳定性.对不同配比的尾砂胶结充填体进行力学试验,得出了其应力-应变规律,对安庆铜矿高阶段充填体变形进行了监测.采用自适应滤波原理,研究基于重构相空间的测量数据去噪处理方法.用灰色理论研究充填体变形在相空间中相点距离的演变规律,建立了重构相空间的灰色预测模型.为减小预测误差,对预测结果采用残差模型修正.应用建立的模型,对安庆铜矿高阶段充填体变形进行分析,确定了采场合理回采周期.结果表明,充填体变形具有非线性混沌特性,不同配比的充填体表现出不同的非线性动力学行为,重构相空间能充分展示充填体变形的内在规律.     

基于CFD-DEM的旋风除尘器内气固流动特性研究

为了研究旋风除尘器内气固流动特性,采用CFD-DEM耦合算法研究不同入口气体速度下旋风除尘器内颗粒流态、静压、径向速度及轴向速度分布特征。结果表明:煤屑颗粒在离心力和径向曳力的作用下以螺旋颗粒条带靠近除尘器的壁面稳定向下移动,随着入口风速的增加煤屑颗粒条带变宽,条带与除尘器的第1次接触的拐点上移,螺距减小;除尘器内部压力轴向变化较小,径向变化较大,随着入口气体速度增加,除尘器壁面附近高压区范围和压力也随之增加,除尘器上方和下方的负压区变宽并朝轴向方向延伸;随入口气体速度增加,除尘器内径向速度和轴向速度逐渐增加,煤屑颗粒在除尘器中部聚集较多,煤屑停留时间变长,入口气体速度为15 m/s时,煤屑颗粒在除尘器内停留时间最长。     

气固两相流90°弯管抗冲蚀结构优化

为了提高天然气输送管道90°弯管的耐磨性能,提出了1种三段弯曲式弯管,通过对弯管弯曲段进行三段式改进来减小弯管中二次流的大小,优化弯管内的流场,改善弯管的冲蚀磨损状况。利用COMSOL仿真软件建立三段式弯管模型,并以弯管弯曲段和出口段二次流平均值之和最小为优化目标,在约束条件下凭借COMSOL中的COBYLA优化算法得到了最优管形;用Fluent对优化后的三段式弯管进行冲蚀数值模拟并与一段式弯管的模拟结果进行对比分析。研究结果表明:与一段式90°弯管相比,优化后的三段式弯管流场更加平稳,其弯曲段的二次流强度大幅降低,弯管壁面的冲蚀磨损程度得到较大的改善。     

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吸烟气相物质引起的脂质过氧化的研究

本文用吸烟气相物质作用于卵磷脂形成的脂质体及人多形核白细胞,用TBA法和共轭二烯法检测吸烟气相物质作用下的脂质过氧化水平,结果发现,随着吸烟气相物质作用时间的延长,MDA和共轭二烯的含量也随之增大。表明吸烟气相物质能够引起脂质过氧化反应。     

聚合物涂层纤维材料为固定相填充毛细管气相色谱及其在样品预处理中的应用

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中温两相UBF反应器处理养鸡场离心废水的试验分析

在中温 35℃采用两相 UBF反应器处理养鸡场离心废水 ,结果表明 :进水 CODcr为 190 0 0 mg/ L,系统容积负荷 2 1.5 4kg CODcr/ m3· d,水力停留时间 2 1.17hr,CODcr去除率为 81.98% ,BOD5 去除率为 90 .45 % ,产气率为 0 .44 6 m3/kg CODcr     

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论述了混沌现象与基本特征，提出把混沌分析方法引入环境科学中，探索环境现象变化的新途径。重点简述混沌现象在环境影响的变迁的实例，环境混沌系统控制的基本思路和混沌分析相空间预测方法。