Removal of arsenate with hydrous ferric oxide coprecipitation：Effect of humic acid

Insights from the adverse effect of humic acid(HA) on arsenate removal with hydrous ferric oxide(HFO) coprecipitation can further our understanding of the fate of As(V) in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As(V) on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering(SERS), extended X-ray absorption fine structure(EXAFS) spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared(ATR-FTIR) measurement, and charge distribution multisite complexation(CDMUSIC) modeling. The As(V) removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As(V) mass concentration. The SERS analysis excluded the HA-As(V) complex formation. The EXAFS results indicate that As(V) formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26–3.31 ?. The in situ ATR-FTIR measurements show that As(V) replaces surface hydroxyl groups and forms innersphere complex. High concentrations of HA may physically block the surface sites and inhibit the As(V) access. The adsorption of As(V) and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As(V) and HA reasonably well.     

Effect of composting on the Cd,Zn and Mn content and fractionation in feedstock mixtures with wood chips from a short-rotation coppice and bark

Micronutrient content and availability in composts may be affected by the addition of wood chips or tree bark as a bulking agent in the compost feedstock. In the first part of this study, micronutrient levels were assessed in bark and wood of poplar and willow clones in a short-rotation coppice. Large differences between species were observed in bark concentrations for Cd, Zn and Mn. In the second part of the study, we aimed to determine the effect of feedstock composition and composting on Cd, Zn and Mn concentrations and availability. By means of three composting experiments we examined the effect of (a) bark of different tree species, (b) the amount of bark, and (c) the use of bark versus wood chips. In general, compost characteristics such as pH, organic matter and nutrient content varied due to differences in feedstock mixture and composting process. During the composting process, the availability of Cd, Zn and Mn decreased, although the use of willow and poplar bark or wood chips resulted in elevated total Cd, Zn or Mn concentrations in the compost. Cd concentrations in some composts even exceeded legal criteria. Cd and Zn were mainly bound in the reducible fraction extracted with 0.5 M NH₂OH?HCl. A higher acid-extractable fraction for Mn than for Cd and Zn was found. Higher Cd concentrations in the compost due to the use of bark or wood chips did not result in higher risk of Cd leaching. The results of the pH-stat experiment with gradual acidification of composts illustrated that only a strong pH decline in the compost results in higher availability of Cd, Zn and Mn.     

Cultural Relevance for Rural Community Development in China: A Case Study in Bai,Jingpo and Huyaodai Communities of Yunnan Province

Abstract

A three-year study over the Bai, Jingpo and Huayaodai communities in Yunnan Province reveals that the community development is significantly influenced in various ways by such cultural factors as the concepts of development; concepts and traditions of inter-community relationships, consumption, marriage and gender; patterns of decision-making and production, resource and income allocation; as well as the role of information dissemination systems, religion and ritual. Based on the analysis over the interactive relevance between each factor and community development, some strategies and methods for dealing with such a cultural relevance in development projects are recommended.     

阪神地震造成的河流损害及对策

介绍了１９９５年日本阪神７．２级地震造成的河流损害、防止次生灾害采取的紧急对策及修复方案，以供我国研究防御地震次生灾害参考。     

N—N—二（1—甲基—庚基）乙酰胺萃取苯酚的动力学研究

用恒界面池法研究了Ｎ,Ｎ－二（１－甲基－庚基）乙酰胺（ＤＭＨＡＡ,Ｎ５０３）萃取苯酚的动力学,试验表明,萃取速率随水相苯酚浓度,有机相Ｎ５０３浓度的提高而增加,当水相ｐＨ值≥１０．５时,萃取速度明显下降,萃取反应的表观活化能为１４．３ｋＪ·ｍｏｌ＾－１,萃取过程属扩散控制,水相中萃酚向两相界面的扩散是萃取速度的控制步骤。     

渭河下游洪水,地震灾害综合风险分析与损失评估

根据渭河下游洪水、地震灾害生成环境建立了洪水、地震灾害叠加模型，进而依据大量实际资料进行了灾害叠加风险水平估计和定量损失计算。     

水射流技术处理软基防渗工程实例

介绍了在西沙群岛永兴岛的特殊地基条件下，采用高压喷射注浆技术对大型地下集水池进行封底，并获得圆满成功的工程实例，总结了采用高压喷射注浆技术处理珊瑚礁（Ｃｏｒａｌｒｅｅｆ） 地基的成功经验     

液化石油气罐区危险性的定量评价

液化石油气罐区的主要危险是贮罐区发生火灾、爆炸事故。运用数学模型对液化石油气贮罐的危险性进行定量化评价，估算其爆炸事故的严重程度、波及范围、影响程度等     

自然灾害的自相似性质

本文分析了多种自然灾害的致灾因子和致灾损失的频次—大小关系，结果表明，普遍服从幂指数分布律，表明存在自相似性和可用分数维度量。地震和洪水等突发性灾害及其造成的损失自相似最明显，分数维可在２～３个量级区间成立。不同文种、致灾因子和致灾损失的分数维值似与成灾机理、影响因子的复杂程度有关．