好氧颗粒污泥的性质及其在脱氮除磷中的应用

阐述了好氧颗粒污泥的污泥特性、培养条件和影响因素 ,比较了三种SBR反应器中颗粒污泥特性的差异 ,介绍了好氧颗粒污泥的形成机理及其在脱氮除磷过程中的应用情况     

城市旅游区暴雨径流污染过程中的不透水面效应

选取武汉市动物园4种典型的不透水面暴雨径流污染特征进行了系统的研究，以期为旅游区面源污染危害评价和治理提供基本的依据。结果表明，动物园4种不透水面初期径流污染物浓度很高，COD最大值达1140mg／L，下垫面类型及地表累积污染物是影响径流水质的主要因素。通过无量纲累积曲线的分析，表明旅游区不透水面径流初期冲刷严重，该曲线还为面源治理提供了重要的工程参数。     

Effects of forest management on soil carbon: results of some long-term resampling studies

The effects of harvest intensity (sawlog, SAW; whole tree, WTH; and complete tree, CTH) on biomass and soil C were studied in four forested sites in the southeastern US (mixed deciduous forests at Oak Ridge, TN and Coweeta, NC; Pinus taeda at Clemson, SC: and P. eliottii at Bradford, FL). In general, harvesting had no lasting effects on soil C. However, intensive temporal sampling at the NC and SC sites revealed short-term changes in soil C during the first few years after harvesting, and large, long-term increases in soil C were noted at the TN site in all treatments. Thus, changes in soil C were found even though lasting effects of harvest treatment were not. There were substantial differences in growth and biomass C responses to harvest treatments among sites. At the TN site, there were no differences in biomass at 15 years after harvest. At the SC site, greater biomass was found in the SAW than in the WTH treatment 16 years after harvest, and this effect is attributed to be due to both the N left on site in foliar residues and to the enhancement of soil physical and chemical properties by residues. At the FL site, greater biomass was found in the CTH than in the WTH treatment 15 years after harvest, and this effect is attributed to be due to differences in understory competition. Biomass data were not reported for NC. The effects of harvest treatment on ecosystem C are expected to magnify over time at the SC and FL sites as live biomass increases, whereas the current differences in ecosystem C at the TN site (which are due to the presence of undecomposed residues) are expected to lessen with time.     

Evaluation of plant availability of soil trace metals by chemical fractionation and multiple regression analysis

Soil samples with a range of chemical and physical properties were collected from 10 different rural regions of China. Trace metals (Ni, Co, Cu, and Pb) in the soils were partitioned by a sequential extraction procedure into Mg(NO(3))(2) extractable (F1), CH(3)COONa extractable (F2), NH(2)OH.HCl extractable (F3), HNO(3)?H(2)O(2) extractable (F4), and residual (F5) fractions. Chemical fractionation showed that F1 fraction of the metals was less than 1% and residue was the dominant form for Cu and Ni in all samples, and for Co in most of the samples. Significant interrelationships of the fractions varied considerably with the different metals. Winter wheat (Triticum aestivum L.) and alfalfa (Medicago sativa L.) had been grown on the soils in a pot-culture experiment under greenhouse conditions for 40 days. Metal availability to the plants was evaluated by simple and multiple regression analysis. The Mg(NO(3))(2) extractable Co (F1) was significantly correlated with Co concentrations in different parts of wheat and in the whole of alfalfa. For the other metals, the independent variables of the multiple regression models, chosen by stepwise selection, were given as: F1 and F2 + F3 + F4 for Ni; F1, F2 + F3 and F4 for Cu; and F3 + F4 for Pb. The results of this study demonstrate that the sequential extraction procedure, in conjunction with multiple regression models using a combination of correlated fractions as an independent variable, may be useful for the prediction of plant absorption of trace metals in soils.     

Disinfection performance of chlorine dioxide gas at ultra-low concentrations and the decay rules under different environmental factors

ABSTRACT

Gaseous chlorine dioxide (ClO₂) is one of the most promising air disinfectants. In this study, an ultra-low concentration of ClO₂ gas (< 1.2 mg/m³) was generated in an office at various levels of humidity and illuminance to investigate the decay law. The disinfection efficiency and metal corrosiveness of ultra-low concentrations of ClO₂ gas were also studied using an experimental chamber. At 48% and 75% humidity, the decay rate constants of ClO₂ gas were 0.0034 min^?1 and 0.0036 min^?1, respectively. The rate of decline of the ClO₂ concentration increased as the humidity of the environment increased. The decay rate constant of ClO₂ gas at an illuminance of 76 lux and 3429 lux was 0.0034 min^?1 and 0.00427 min^?1, respectively; hence, the decay rate increased with increased illumination. At a humidity of 72% and illuminance of 2112 lux, the decay rate constant reached 0.00880 min^?1. The effects of humidity and illuminance on the attenuation of the ClO₂ concentration were strongly synergistic. When the gas concentration was maintained below 0.9 mg/m³, the disinfection rate of ClO₂ on bacteria (P. aeruginosa, V. mimicus and S. aureus) exceeded 99.9%; thus, ClO₂ gas exhibited a high disinfection efficiency. In addition, there was no corrosion to various metals by ClO₂ under the same conditions. Consequently, gaseous ClO₂ at ultra-low concentrations has a high sterilization efficiency and is non-corrosive to metals.     

海河流域土壤中硫的分布特征

本文对海河流域不同土壤类型中硫及其形态的含量分布、水平及垂直变化进行探讨,研究其在一定条件下土壤中硫的自然富集、增减途径、自身循环环境以及分布特征。为研究本区硫的库存量及流通量循环体系奠定一定基础。     

高压水射流超细粉碎的压力与粒度的关系

从理论分析和实验研究两方面，对高压水射流超细粉碎压力与粒度的定量关系进行了研究。根据流体力学理论，推导出粉体颗粒的动能与射流压力成正比；再由Ｒｉｔｔｉｎｇｅｒ的“表面积假说”，得出高压水射流超细粉碎的压力与产品调和平均粒度倒数和给料调和平均粒度倒数之差成正比；并在不同压力和给料粒度下，用水射流对云母粉进行了超细粉碎实验。实验结果与理论结果相当吻合。     

中国高硫煤的分布及脱硫现状

本文评论介绍了中国高硫煤的分布规律,分析了中国高硫煤的化学组成,概述了中国高硫煤脱硫技术的现状。作者认为,根据中国目前的情况,高硫煤的洗选脱硫是一项减少SO_2对大气排放量的切实可行而又经济的办法。     

掘进巷道风流温度分布规律的数值模拟

根据紊流状态下的守恒原理 ,导出了描述掘进巷道风流紊流流动和温度分布的微分方程。通过对矿内风流流动及热力过程的理论分析及现场实测 ,系统地开展矿内风流流场和风流温度场的分布规律及其耦合作用机理的理论分析与研究 ,并利用PHOENICS程序进行数值模拟 ,初步得出了矿井掘进巷道风流温度与各种参数的变化规律。掘进巷道风流温度随风速提高呈负幂函数规律降低 ,随入风流温度升高而线性升高。     

中国环境政策矩阵的构建与分析

可持续发展战略要求对已有的环境政策手段进行重新评估。由世界银行提出的环境政策矩阵则是进行这种评估的成功之举。本文利用政策矩阵这一模式探讨了我国环境政策手段的构成与特点，并进而提出了创新我国环境政策手段的几点建议，以促进我国可持续发展战略的实施。