三峡工程建设前后库区城镇发展与环境变化

利用卫星遥感监测,分析三峡工程建设前后库区城镇发展类型、时空过程,揭示库区城镇变化的驱动力,探索了城镇扩展与人口城镇化关系,研究城镇环境变化特征。三峡库区城镇规模发展不均衡,库尾城市规模庞大,库中、东部区县级城市规模较小,而乡镇的比例占城镇面积24%;在过去15 a中,建城区规模扩大172%,高于全国省会城市发展水平72%;三峡库区城镇规模扩大的同时,东西城镇规模差距逐步缩小,三峡工程建设起着重要的推动作用;城镇发展以侵占了优质耕地资源为代价,耕地占城镇变化83%;城镇用地变化与人口城市化发展不平衡,城镇空间发展快于人口城镇化过程,城镇对农村人口的吸引力不及全国省会城市平均水平,在2007年城市化率低于全国水平13%,差距进一步扩大;城市空间结构发展模式受地形和土地资源的限制,城市分维数和坡度分别增加12%和104°,城市向潜山区扩展或搬迁的同时,城市空间的完整性下降     

Transport of copper as affected by titania nanoparticles in soil columns

The effects of TiO₂ nanoparticles on the transport of Cu through four different soil columns were studied. For two soils (HB and DX), TiO₂ nanoparticles acted as a Cu carrier and facilitated the transport of Cu. For a third soil (BJ) TiO₂ nanoparticles also facilitated Cu transport but to a much lesser degree, but for a fourth soil (HLJ) TiO₂ nanoparticles retarded the transport of Cu. Linear correlation analysis indicated that soil properties rather than sorption capacities for Cu primary governed whether TiO₂ nanoparticles-facilitated Cu transport. The TiO₂-associated Cu of outflow in the Cu-contaminated soil columns was significantly positively correlated with soil pH and negatively correlated with CEC and DOC. During passage through the soil columns 46.6-99.9% of Cu initially adsorbed onto TiO₂ could be “stripped” from nanoparticles depending on soil, where Cu desorption from TiO₂ nanoparticles increased with decreasing flow velocity and soil pH.     

Zinc accumulation and synthesis of ZnO nanoparticles using Physalis alkekengi L

A field survey and greenhouse experiments were conducted using Physalis alkekengi L. to investigate strategies of phytoremediation. In addition, ZnO nanoparticles were synthesized using P. alkekengi. P. alkekengi plants grew healthily at Zn levels from 50 to 5000 mg kg⁻¹ in soils. The plants incorporated Zn into their aerial parts (with mean dry weight values of 235-10,980 mg kg⁻¹) and accumulated biomass (with a mean dry weight of 25.7 g plant⁻¹) during 12 weeks. The synthesized ZnO nanoparticles showed a polydisperse behavior and had a mean size of 72.5 nm. The results indicate that P. alkekengi could be used for the remediation of zinc-contaminated soils. Moreover, the synthetic method of synthesizing ZnO nanoparticles from Zn hyperaccumulator plants constitutes a new insight into the recycling of metals in plant sources.     

Biosorption of zinc and copper from aqueous solutions by two freshwater green microalgae Chlorella pyrenoidosa and Scenedesmus obliquus

Purpose

The objective of this study was to determine the removal of zinc and copper by two freshwater green microalgae Chlorella pyrenoidosa and Scenedesmus obliquus and to investigate changes of algal ultrastructure and photosynthetic pigment.

Methods

Algal cells were exposed for 8 days to different initial zinc or copper concentrations. Heavy metal concentrations were detected by an atomic absorption spectrophotometer. Algal growth, ultrastructure, and photosynthetic pigment were analyzed by a microplate reader, transmission electron microscope, and spectrophotometer, respectively.

Results

Low zinc and copper concentrations induced increase in algal growth, whereas application of high zinc and copper concentrations suppressed the growth of both algae. High metal concentrations also decreased the photosynthetic pigments and destroyed algal cell ultrastructure. The zinc removal efficiency by both algae increased rapidly during the first day and thereafter remained nearly constant throughout the experiment. The copper removal efficiency by both algae increased slowly during the whole experimental periods. In all cultures, the quantity of both metals removed intracellularly was much lower than the adsorbed quantity on the cell surface.

Conclusions

Both strains of the microalgae had proven effective in removing zinc and copper from aqueous solutions, with the highest removal efficiency being near 100%. In addition, C. pyrenoidosa appeared to be more efficient than S. obliquus for removing copper ions. On the contrary, S. obliquus appeared to be more efficient than C. pyrenoidosa for removing zinc ions.     

液相色谱/质谱联用检测刚果红及其微电解降解的研究

采用液相色谱/质谱联用(LC/MS)检测了模拟印染废水中的刚果红,并用微电解对其进行了降解研究.LC/MS检测刚果红的结果表明,在流动相为甲醇:水(体积比)=70:30、流速为0.6 mL/min、色谱柱为Zorbax XDB0-C18(150 mm× 4.6 mm,5μm)条件下,刚果红的准分子离子的质荷比(m/z)...     

Dissipation of carbendazim and chloramphenicol alone and in combination and their effects on soil fungal:bacterial ratios and soil enzyme activities

The dissipation of carbendazim and chloramphenicol alone and in combination and their effects on soil fungal:bacterial ratios and soil enzyme activities were investigated. The results revealed that carbendazim dissipation was little affected by chloramphenicol, whereas chloramphenicol dissipation was found to be retarded significantly by the presence of carbendazim. The inhibitory effect of carbendazim on the fungal:bacterial ratios was increased by the presence of chloramphenicol, and the inhibitory effect of chloramphenicol on neutral phosphatase was increased by the presence of carbendazim. Carbendazim increased soil catalase and urease activities, but this increase was partially diminished by the presence of chloramphenicol. Little interaction was observed between carbendazim and chloramphenicol with regard to their influence on soil invertase. The results obtained in this study suggest that combinations of fungicides and antibiotics may alter the compounds’ individual behaviors in soil and their effects on soil enzymes.     

Fenton-双泥SBR工艺深度处理难降解反渗透浓缩液

采用Fenton试剂处理反渗透浓缩渗滤液(简称浓缩液),并探讨了双泥SBR工艺对Fenton处理后浓缩液与人工配水混合处理的可行性.结果表明,Fenton氧化对COD、TN和NH3-N的平均去除率分别为43.5%、22.5%和19.5%.对溶解性有机物(DOMs)的去除率为52.5%,其中胡敏酸(HA)、富里酸(FA)...     

等离子体固态可燃物液化反应动力学分析

本文利用介质阻挡放电等离子体技术,对以煤和生物质为代表的固态可燃物液化反应机理进行研究,以期探索能源利用新途径.借助碰撞理论和Boltzman方程,对高能电子碰撞引发多种离解反应的速率常数进行数值模拟,计算结果和实验曲线对比,证明模型具有一定的适用性和可靠性.在一定的电子温度下,通过不同离解反应速率常数的对比,可以判断...     

不同营养水平下悬浮细菌数量对生物粘泥性质的影响

循环水系统中的微生物有悬浮态和附着态,悬浮细菌的存在对附着态生物粘泥的生长及特性有明显影响。通过向模拟循环冷却水系统中投加不同数量初始悬浮细菌,考察在营养水平不同的情况下,悬浮细菌数量对生物粘泥化学组成和脱氢酶活性的影响。结果表明,营养水平不同,初始悬浮细菌数量对生物粘泥的化学组成和脱氢酶活性的影响程度不同;在不同营养水平下,应分别控制初始悬浮细菌数量。贫营养下,初始悬浮细菌数量应控制在6×105个/mL左右;中营养下,初始悬浮细菌数量应控制在1×105～2.6×105个/mL之间;富营养下,初始悬浮细菌数量应控制在0.11×105～2.6×105个/mL之间最不利于生物粘泥的生长。