WETLAND ECOSYSTEM STUDIES FROM A HYDROLOGIC PERSPECTIVE1

ABSTRACT: Selected studies from the literature were reviewed to determine the extent of knowledge about the relationship between hydrology and wetland ecosystem studies. Wetland studies of chemical input-output relationships have been the most dependent on hydrologic data of all wetland investigations; yet, very few of these studies have attempted to measure all components of a wetland's water balance. Usually, unmeasured components were calculated as the difference between measured inputs and outputs. Ground water frequently was overlooked. Chemical input-output investigations primarily were concerned with determining the amount of input retained in the wetlands. Few studies also included direct measurement of biogeochemical processes within wetlands of elements that were part of simultaneous input-output investigations. The importance of uncertainties in chemical budgets that are due to uncertainties in hydrologic budgets has been addressed in very few wetland investigations. Although many studies have emphasized the importance of hydrology to wetland ecosystem research, few studies have documented this, so that hydrology remains one of the least understood components of wetland ecosystems.     

酸沉降物对土壤化学性质的影响

本文综述了酸沉降物对土壤酸化、营养物质的淋溶、重金属的活化、矿物分解等化学性质的影响，以及阻止酸雨危害土壤的化学方法。     

CHEMICAL ANALYSIS OF CO2 REMOVAL IN TRAY AERATORS1

ABSTRACT: This paper presents a discussion of the chemistry of CO₂ removal in tray aerators, and different sets of equations that are applicable to several initial water chemical conditions are proposed. These chemical equations and a statistical model to predict the kinetic constant were tested with field data observed by other researchers in pilot units and in a full scale plant. The water temperature in their experiments was around 15°C.     

用固体力学化学理论研究岩土的力学化学行为——以成都龙泉紫色土为例

根据固体力学化学理论 ,提出用化学动力学方法研究岩土破坏及滑坡形成的机理 ,并以成都龙泉紫色土为例研究了在力与水协同作用下易滑土层的力学化学行为。实验表明 ,土长期抗剪强度降低的幅度与溶液的pH值有关 ,土的溶解速度与易溶盐含量有关 ,且溶解曲线略呈“S”型。这初步证明了龙泉紫色土破坏的力学 化学效应及其可能存在的自催化趋势。通过实验了解了力与水协同作用导致土破坏的力学化学规律 ,并将定量求解滑面长期抗剪强度与反应机理研究结合起来 ,为定量评价地下水和应力对岩土破坏机理这一滑坡学关键问题打下基础。     

采用两级物化法去除黄磷废水中的氟化物

采用向含氟废水中加入适量石灰和聚合氯化铝，然后投加适量钙盐、磷酸和聚丙烯酰胺的二级处理工艺除氟，通过控制合适的pH、钙盐和磷酸的投加量、反应时间、反应温度、搅拌强度和絮凝剂的投加量，可使黄磷废水中氟的质量浓度降至5mg/L，氟的去除率达到99％以上，出水中氟的质量浓度达到GB8978－1996一级排放标准。     

我国化学工业的“三废”及其资源化

文章在介绍我国化学工业排放三废的严峻现状后,阐述了通过工艺改造和综合回收途径来推进三废资源化的技术对策,以及从宏观和微观上看深化三废资源化的意义和光明前景。     

FACTORS THAT AFFECT ACTIVATED SLUDGE PHOSPHATE RELEASE1

The activated sludge process can remove significant amounts of phosphorus from sewage, but the removal efficiency is usually significantly reduced by the release of phosphate back to solution during subsequent treatment steps. This research presents a study of soluble phosphate release from activated sludge with emphasis on defining the factors that affect such release and the actual release mechanisms. Laboratory units were used for experimental purposes. The experiments were designed to study the relationship between soluble phosphate release and various environmental factors such as redox potential (ORP), dissolved oxygen (DO), pH, solids concentration, solids destruction, and sulfate salt addition. The effect of substrate utilization on phosphate uptake and the relationship between uptake characteristics and subsequent phosphate release were also studied. The results show that some phosphate storage occurs during aerobic substrate utilization. Following substrate utilization, activated sludge phosphate release is directly related to the amount of biological stress the organisms are subjected to, and the mechanism of release is primarily cell lysis. The phosphate released per unit sludge under anoxic conditions is relatively constant. Under normal environmental conditions, neither ORP or pH change have a significant affect on phosphate release.     

化学工业园区规划环评指标体系初探

本文以某化工园区规划环评为例,根据化工区的行业特点,在总结国内外相关研究的基础上,探讨了化工园区规划环评指标体系设置原则和基本程序。在充分考虑了发展循环经济和生态工业、实现区域可持续发展、持续推进清洁生产等方面的基础上,通过基础指标初步筛选、多角度指标分析和专家咨询、公众参与等三个步骤的筛选,最终形成了一套适合于该化工园区规划环评指标体系。     

微波消解法快速测定渗滤液化学需氧量

针对国标回流法测定化学需氧量消耗时间长,分析费用高等不足,研究了微波消解法测定垃圾渗滤液的试验方法.通过微波消解功率、消解时间、催化剂用量等试验,确定了微波消解测定渗滤液CODCr的最佳条件.该方法具有省时间、省试剂、准确度高等优点.     

Planar detonation structure for chain-branching kinetics with large activation energy and small initiation rate

The structure of the steady planar detonation wave is analyzed for three-step chain-branching kinetics consistent with hydrogen–air chemistry. The initiation and chain-branching steps are described by an Arrhenius rate. Both are thermally neutral, so that heat release is due to termination. The initiation rate is typically very low and very stiff. As a result, a small fraction of the reactant is consumed in the initiation region, which is very long but ends in an exponential chain-branching explosion. Next, the reactant is rapidly converted into chain-branching radicals, within a very thin zone, which ends when the concentration of the chain-branching radical reaches a peak, because of reactant depletion. Finally, the termination step consumes the chain-branching radicals and releases heat within a region thicker than the peak zone, but much thinner than the initiation region. The analysis is based upon two assumptions: that the chain-branching activation energy is high and that initiation is slow. The structure of the initiation and chain-branching zones is different for post-shock states within or outside the explosion region in the chain-branching diagram. In the former situation, chain-branching is already stronger than termination at the von Neumann point, and vice versa. In the no-explosion case, the initiation zone becomes very long, while the little chain-branching specie produced by initiation is directly converted into product by the termination step. Temperature increases slowly until reaching the explosion curve, when chain-branching becomes stronger than termination. The subsequent structure is similar to the explosion case.