Arsenic and cadmium removal from water by a calcium-modified and starch-stabilized ferromanganese binary oxide

A new calcium-modified and starch-stabilized ferromanganese binary oxide (Ca-SFMBO) sorbent was fabricated with different Ca concentrations for the adsorption of arsenic (As) and cadmium (Cd) in water. The maximum As(III) and Cd(II) adsorption capacities of 1% Ca-SFMBO were 156.25 mg/g and 107.53 mg/g respectively in single-adsorption systems. The adsorption of As and Cd by the Ca-SFMBO sorbent was pH-dependent at values from 1 to 7, with an optimal adsorption pH of 6. In the dual-adsorbate system, the presence of Cd(II) at low concentrations enhanced As(III) adsorption by 33.3%, while the adsorption of As(III) was inhibited with the increase of Cd(II) concentration. Moreover, the addition of As(III) increased the adsorption capacity for Cd(II) up to two-fold. Through analysis by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR), it was inferred that the mechanism for the co-adsorption of Cd(II) and As(III) included both competitive and synergistic effects, which resulted from the formation of ternary complexes. The results indicate that the Ca-SFMBO material developed here could be used for the simultaneous removal of As(III) and Cd(II) from contaminated water.     

Water regime-nitrogen fertilizer incorporation interaction: Field study on methane and nitrous oxide emissions from a rice agroecosystem in Harbin, China

Water regime and nitrogen (N) fertilizer are two important factors impacting greenhouse gases (GHG) emission from paddy field, whereas their effects have not been well studied in cold region. In this study, we conducted a two-year field experiment to study the impacts of water regime and N fertilizer on rice yields and GHG emissions in Harbin, China, a cold region located in high latitudes. Our results showed that intermittent irrigation significantly decreased methane (CH₄) emission compared with continuous flooding, however, the decrement was far lower than the global average level. The N₂O emissions were very small when flooded but peaked at the beginning of the disappearance of floodwater. The N fertilizer treatments increased CH₄ emissions at low level (75kgN/ha). But both CH₄ and N₂O emissions were uninfluenced at the levels of 150kgN/ha and 225kgN/ha. Rice yields increased under intermittent irrigation and were highest at the level of 150kgN/ha. From our results, we recommended that the intermittent irrigation and 150kgN/ha as the ideal water regime-nitrogen fertilizer incorporation for this area to achieve low GHG emissions without impacting rice yields.     

Adsorption-oxidation of hydrogen sulfide on Fe/walnut-shell activated carbon surface modified by NH3-plasma

Walnut-shell activated carbon(WSAC) supported ferric oxide was modified by non-thermal plasma(NTP), and the removal efficiency for hydrogen sulfide over Fe/WSAC modified by dielectric barrier discharge(DBD) was significantly promoted. The sample modified for10 min and 6.8 k V output(30 V input voltage) maintained 100% H2 S conversion over a long reaction time of 390 min. The surface properties of adsorbents modified by NTP under different conditions were evaluated by the methods of X-ray photoelectron spectroscopy(XPS), Brunauer–Emmett–Teller(BET) analysis and in-situ Fourier transform infrared spectroscopy(FTIR), to help understand the effect of the NTP treatment. NTP treatment enhanced the adsorption capacity of Fe/WSAC, which could due to the formation of micro-pores with sizes of0.4, 0.5 and 0.75 nm. XPS revealed that chemisorbed oxygen changed into lattice oxygen after NTP treatment, and lattice oxygen is beneficial for H2 S oxidation. From the in-situ FTIR result,transformation of the reaction path on Fe/WSAC was observed after NTP modification. The research results indicate that NTP is an effective method to improve the surface properties of the Fe/WSAC catalyst for H2 S adsorption-oxidation.     

Measurement of hydrogen peroxide and organic hydroperoxide concentrations during autumn in Beijing, China

Gaseous peroxides play important roles in atmospheric chemistry. To understand the pathways of the formation and removal of peroxides, atmospheric peroxide concentrations and their controlling factors were measured from 7:00 to 20:00 in September, October, and November 2013 at a heavily trafficked residential site in Beijing, China, with average concentrations of hydrogen peroxide (H₂O₂) and methyl hydroperoxide (MHP) at 0.55 ppb and 0.063 ppb, respectively. H₂O₂ concentrations were higher in the afternoon and lower in the morning and evening, while MHP concentrations did not exhibit a regular diurnal pattern. Both H₂O₂ and MHP concentrations increased at dusk in most cases. Both peroxides displayed monthly variations with higher concentrations in September. These results suggested that photochemical activity was the main controlling factor on variations of H₂O₂ concentrations during the measurement period. Increasing concentrations of volatile organic compounds emitted by motor vehicles were important contributors to H₂O₂ and MHP enrichment. High levels of H₂O₂ and MHP concentrations which occurred during the measurement period probably resulted from the transport of a polluted air mass with high water vapor content passing over the Bohai Bay, China.     

基于公私合营管理模式在城市生活垃圾处理中的应用研究

提出基于公私合营的政府管理模式在城市生活垃圾处理中的应用研究,对公私合营的政府管理模式具有的"伙伴关系、利益共享、风险共担"三大特征进行了分析;借鉴当前学术界存在的一些公私合营的政府管理模式类型,与城市生活垃圾治理的行业特征进行有机结合,将公私合营的政府管理模式分为公有私营模式、公私合资模式和特许经营模式三大类,分析这些模式在城市生活垃圾处理中的具体应用,实现政策性与效益性的双赢发展机制,对改善城市居民生活环境,促进城市经济和社会的高质量发展具有重要意义。     

GIS在震后应急反应中的应用

震后应急反应是减轻震害的关键措施之一。震后应急的基础在于信息的收集和处理。ＧＩＳ（地理信息系统）具有很强的信息管理能力和空间数据处理、分析能力。借助于这个系统,可以解决以往应急反应中存在的资料分散、资料更新慢、管理费用大以及大量信息难以提取、查询和使用等问题。ＧＩＳ与震后应急反应的结合可以大大提高应急反应的速度和准确性。     

Enhancement of dissolved phosphorus release from sediment to lake water by Microcystis blooms--an enclosure experiment in a hyper-eutrophic,subtropical Chinese lake

To clarify the possible influence of Microcystis blooms on the exchange of phosphorus (P) between sediment and lake water, an enclosure experiment was conducted in the hypereutrophic subtropical Lake Donghu during July-September 2000. Eight enclosures were used: six received sediment while two were sediment-free. In mid-August, Microcystis blooms developed in all the enclosures. There was a persistent coincidence between the occurrence of Microcystis blooms and the increase of both total P (TP) and soluble reactive P (SRP) concentrations in the water of the enclosures with sediments. In sediment-free enclosures, TP and SRP concentrations remained rather stable throughout the experiment, in spite of the appearance of Microcystis blooms. The results indicate that Microcystis blooms induced massive release of P from the sediment, perhaps mediated by high pH caused by intense algal photosynthesis, and/or depressed concentrations of nitrate nitrogen (NO3-N).     

Fe（Ⅲ）水解过程中无机阴离子的影响作用

本文通过ＰＯ＾３－ ４，Ｆ＾－，ＳＯ＾２－ ４，Ｃｌ＾－，ＮＯ＾－ ３和ＣｌＯ＾－ ４存在时，０．１ｍｏｌ／１ ＦｅＣｌ３溶液的碱中和曲线的分析对比，说明了用曲线斜率区分滴定曲线为三个区域：（Ａ）自发水解反应；（Ｂ）聚合反应；（Ｃ）沉淀反应，以及阴离子对中和曲线的影响及其规律，指出阴子子对Ｆｅ（Ⅲ）浓度中和反应影响为不同程度的竞争配位，参与聚合及电中和脱稳，使沉淀反应提前等。并与ＯＨ＾－共同形成Ｆ     

聚合铝絮凝动态过程研究

本文采用新型动脉动絮凝检测技术，测定了不同碱化度（Ｂ值）的聚合铝凝聚絮凝过程中絮集物颗粒的形成与增长过程的动态变化差异，结果表明，该技术对监测凝聚絮凝过程中絮集物的形成与增长是十分敏感的，絮凝指数（Ｒ）可在线地反映絮集物动态增长过程的变化，高碱化度聚合铝（Ｂ＝２．５），比低碱化度聚合铝及氯化铝具有更快的絮凝絮凝速度和形成更大的絮集物颗粒，通过絮凝指数的测定，并结合剩余浊度和ζ电位测定数据，为深入了