Effects of low temperature on aluminum(III) hydrolysis: Theoretical and experimental studies

In this study, the effects of low temperature on aluminum(III) (Al) hydrolysis were examined both theoretically and experimentally by constructing a solubility diagram for amorphous aluminum hydroxide (Al(OH)3(am)) and a distribution diagram of hydrolyzed Al species. First, thermodynamic data of Al species at 4 degrees C were calculated from that at 25 degrees C. A well confirmed polymeric Al species, AlO4Al12(OH)24(7+)(Al13), was involved in building the diagrams and, correspondingly, the non-linear simultaneous equations with 13 degrees were resolved. Secondly, polarized Zeeman atomic absorption spectrophotometry (AAS), 27Al nuclear magnetic resonance (NMR) spectroscopy, and ferron-based spectrophotometry were applied for constructing the practical diagrams. The results show that a decrease of temperature from 25 to 4 degrees C caused the Al(OH)3(am) boundary on the solubility diagram to shift toward the alkaline side by about 1.0 pH unit and the minimum solubility of Al(OH)3(am) to reduce by 1.0 log unit. The distribution diagram indicates that the monomeric Al, Al13, and solid-phase Al(OH)3 were alternately the predominant species with the increase of pH value during Al hydrolysis. At 25 degrees C, Al13 was the dominant species in a pH range of 4.0 to 4.5, whereas at 4 degrees C, All3 was the leading species in a pH range spaced from 4.5 to 6.3. The predominant species changed from the monomeric Al to the solid-phase Al(OH)3 over the range of 1.8 pH units at 4 degrees C in comparison with the range of 0.5 pH unit at 25 degrees C.     

The acute lethality and endocrine effect of 1,2,3,7,8-PeCDD in juvenile goldfish （ Carassius auratus ） in vivo

1,2,3,7,8-PeCDD was administrated to juvenile goldfish （Carassius auratus） by peritoneal injections to explore the acute lethality and endocrine effects of 1,2,3,7,8-PeCDD in vivo. The value of acute median lethal dosage （LD50） of 1,2,3,7,8-PeCDD was determined in acute lethality tests. The endocrine effect of 1,2,3,7,8-PeCDD, whose exposed concentrations were determined based on the LD50 （1.84 mg/kg）, was studied by measuring the plasma vitellogenin （Vtg） content in juvenile male goldfish with enzyme-linked immunosorbent assays （ELISA）. Due to its significant induction of the plasma Vtg after one week＇s exposure in vivo in the 1/2 LD50 and LD30 groups, 1,2,3,7,8-PeCDD might be one of the important contributors to the estrogenic effect of PCDDs in the environment. The values of 1/2 LD50 and LD30 were within the range of the effective dosages of 1,2,3,7,8-PeCDD, indicating that there was a certain relationship between the estrogenic effective dosages and the LD50.     

Characterization of depth-related microbial communities in lake sediment by denaturing gradient gel electrophoresis of amplified 16S rRNA fragments

The characterization of microbial communities of different depth sediment samples was examined by a culture-independent method and compared with physicochemical parameters, those are organic matter （OM）, total nitrogen （TN）, total phosphorus （TP）, pH and redox potential （Eh）. Total genomic DNA was extracted from samples derived from different depths. After they were amplified with the GC-341 f/907r primer sets of partial bacterial 16S rRNA genes, the products were separated by denaturing gradient gel electrophoresis （DGGE）. The profile of DGGE fingerprints of different depth sediment samples revealed that the community structure remained relatively stable along the entire 45 cm sediment core, however, principal-component analysis of DGGE patterns revealed that at greater sediment depths, successional shifts in community structure were evident. The principle coordinates analysis suggested that the bacterial communities along the sediment core could be separated into two groups, which were located 0-20 cm and 21-45 cm, respectively. The sequencing dominant bands demonstrated that the major phylogenetic groups identified by DGGE belonged to Bacillus, Bacterium, Brevibacillus, Exiguobacterium, γ-Proteobacterium, Acinetobacter sp. and some uncultured or unidentified bacteria. The results indicated the existence of highly diverse bacterial community in the lake sediment core.     

浅谈高浓度氨氮废水处理的可持续发展方向

基于可持续发展观念,简评了目前一些常用的和新研发的氨氮废水处理方法,认为既能高效脱氮又能充分回收氨的磷酸铵镁(MAP)沉淀法和可节能减耗的生物脱氮新工艺,将是未来高浓度氨氮废水处理的优先选择和发展方向。     

固定化泛菌对底泥中孔雀石绿的降解

用2%海藻酸钠对孔雀石绿高效降解菌Pantoea sp.EF192586菌株进行固定化包埋,研究固定菌对底泥中孔雀石绿的降解情况。研究结果表明:固定菌对底泥中不同浓度孔雀石绿均有降解,且0.45和0.95μg/g干重降解率更好,达80%。增加固定菌的投菌量可提高降解速率和降解率,但当投菌量增至1.5g后降解率不再增加。泥水系统中水量减少可以提高固定菌起始阶段的降解速率。当固定菌和光照联合作用时可以提高降解率。     

UBF两相生物反应器对渗滤液水质的稳定化作用

为解决渗滤液直接回灌型垃圾填埋反应器(R1)的酸化问题,利用厌氧污泥复合床(UBF)和卫生填埋反应器组合为垃圾两相厌氧消化系统(R2)对垃圾降解。结果表明,与渗滤液直接回灌的R1生物反应器系统相比,UBF型两相厌氧生物反应器系统对渗滤液中有机物质的去除率更高,COD降至24600mg/L,NH3-N浓度保持在1130mg/L,pH值始终维持在7.26,为垃圾渗滤液的后续处理工艺提供了方便。此外,UBF型两相厌氧生物反应器产气性能更好,累积产气量是R1的3.06倍。     

环境库兹涅茨曲线在规划环评中应用的探讨

以可持续发展为目标的规划环评要求对规划区域的社会经济与环境状况的相关性进行分析。文章引进了环境库兹涅茨曲线(EKC),用于福建省某一石化工业基地的规划环评中的经济发展与环境保护协调性分析,研究了当地经济与工业废物排放的耦合程度,丰富了规划环评的方法。     

药剂法去除矿井水中多种有害物质的应用研究

根据某一煤矿矿井水水质特点,采用在矿井水净化处理工艺过程中投加药荆的方法,达到同时去除矿井水中的悬浮物、碳酸盐硬度和铁等多种有害物质的目的。工程试验表明,聚合氯化铝投加量100mg／L,石灰投加量120-140mg／L,二氧化氯投加量大于1．5mg／L时,可以取得较好的处理效果。     

住宅设计中的噪声控制

针对住宅给排水工程中水泵机组、水箱、排水管等产生的噪声问题进行了探讨,并提出解决方法.     

军用包装箱材料自然环境老化XPS研究

通过改性聚苯乙烯试样在拉萨和漠河户外暴露试验,利用X射线光电子能谱（XPS）探讨了改性聚苯乙烯材料表面老化机制。测试结果表明,漠河站试样表现出背阳面比朝阳面光老化程度高;而拉萨站试样户外暴露两年后样品表面氧原子占到47．21％,根据结合能大小可将Cls峰的C分解成C-C（285．0eV）、C～0（（286．6±0．2）eV）和O—C—O（（289．0±0．2）eV）,其中C—O和0=C—O所占比例分别为26．62％和5．64％。