Responses of decomposition rate and nutrient release of floating-leaved and submerged aquatic macrophytes to vertical locations in an urban lake (Nanhu Lake,China)

A leaf-bag field experiment was conducted to investigate the decomposition and release of nutrients from leaves of two aquatic macrophytes (floating-leaved Trapa bispinosa and submerged Vallisneria natans) deposited in the four vertical locations (i.e. air-water interface, AW; sediment-water interface, SW; buried at a depth of 10?cm, B10; buried at a depth of 20?cm, B20) of littoral zone in Nanhu Lake, China, for 60 days from July to August 2015. Leaf initial quality significantly influenced mass loss and nutrient release except TN (total nitrogen) remaining. Compared to V. natans, T. bispinosa leaves decomposed faster under the same treatments. The decomposition was greatly affected by both leaf chemical quality and the location of deposition. With the increasing depth of vertical locations, leaf biomass loss and nutrient release of both T. bispinosa and V. natans decreased. In addition, initial N:P ratio and cellulose were the major determinants for decomposition in AW and SW treatments while total phenol in B10 and B20. Our results suggest that the combined effect of leaf chemical quality and burial could mediate macrophyte mass loss and release of nutrients and carbon, which in turn can influence organic matter accumulation and nutrient cycling in shallow freshwater lakes.     

Solubility and calorimetric study of the effects of gas environment on the decomposition of o-nitrobenzoyl chloride

When ortho-nitrated benzoic acids are chlorinated in xylene and acetonitrile, the product gases, HCl and SO₂, dissolve in the solvent mixture. Previously measured solubilities [Lever, S. D., Papadaki, M. (2004a). o-Chlorination of 2-nitrobenzoic acid with thionly chloride in xylene and acetonitrile. Solubility study of hydrogen chloride and sulphur dioxide in xylene and acetonitrile, IChemE transactions part B. Process Safety and Environmental Protection. 48–60.] were compared to other published data and found to be in very good agreement. The heat of solution of SO₂ in xylene was evaluated calorimetrically and compared to the value obtained from our previous experimental work. In our previous work [Lever, S. D., Papadaki, M. (2004b). Study of condition-dependent decomposition reactions—the thermal behaviour and decomposItion of 2-nitrobenzoyl chloride part_I. Journal of Hazardous Materials. 115; pp. 91–100], it was reported that the products of the decomposition are condition dependent. The current study showed that the decomposition is extensively promoted by the presence of HCl. This has important safety implications should the process operating temperature be reduced and HCl solution in the solvent mixture be increased. If a thermal runaway began in the increased availability of HCl, an undesirable escalation of the runaway could occur.     

序批式生物膜法处理屠宰废水

序批式生物膜法是将微生物培养在软性纤维填料上，形成生物膜后悬挂在废水处理反应器内，废水中溶解污染物在与生物膜的接触中被微生物分解，使水体得到净化。该方法较活性污泥法具有生物量大、抗冲击负荷强、操作简单、有机和无机污染物去除率高等优点。处理后的屠宰废水能够达标排放。     

A SURROGATE-PARAMETER APPROACH TO MODELING GROUNDWATER BASINS1

ABSTRACT: A surrrogate-prarmeter approach to modeling groundwater basins is presented, which has the following advantages over current simulation-type methods: (i) conducivness to modeling nonhomogeneous and nonisotropic basins; (ii) there is no need to guess boundary conditions if accurate information is not available; (iii) the model is amenable to systematic calibration or identification through the use of optimization techniques; and (iv) compatibility with systematic algorithms for analyzing a wide range of management strategies. Since the parameter identification problem is large-scale and nonconvex, it is decomposed through application of generalized duality theory, into several subproblems of smaller size which are solved independently a number of times in order to achieve an overall solution. Results are presented for a hypothetical system of four interacting wells.     

有机过氧化物热分解激烈度的危险性评价方法

采用小型密闭式压力容器试验(MCPVT)测定了有机过氧化物热分解产生的压力举动，根据压力(P)及其上升速度(dP/dt)考察了有机过氧化物热分解激烈度，并与压力容器试验(PVT)进行比较，寻找MCPVT与PVT之间的关系，给出了热分解激烈度的评价方法。实验结果表明，除热分解前即产生蒸发的物质外，MCPVT的最大压力上升速度(dP/dt)max与PVT的最小孔径(d)有良好的相关性。同时指出，对分解前产生蒸发的物质，不适合用PVT进行热分解激烈度的评价，应采用MCPVT进行评价。     

基于碳同位素组成的大气NMHCs光化学寿命研究

利用热解析-气相色谱-同位素质谱联用仪测定了兰州市冬季和夏季昼夜大气非甲烷烃(NMHCs)的稳定碳同位素组成.结果表明,兰州市冬季大气NMHCs的δ13C值为-30.5‰～-24.3‰,夏季为-31.9‰～-24.2%,受燃煤烟气排放的影响,冬季大气NMHCs的δ13C值明显大于夏季;冬季大气NMHCs的δ13C值夜晚大于白天,夏季不同时间点C4、C5化合物的同位素值相差不大,正己烷和正庚烷的δ13C值白天比夜晚要高.利用"碳氢化合物同位素时钟"计算出正己烷和1-丁烯在兰州市夏季大气中的平均光化学寿命分别约为6d和25min.     

三唑酮在水体系中的光化学降解研究

系统研究了在天然日光和高压汞灯照射下三唑酮在蒸馏水、人工海水和天然海水中的光降解情况.结果表明,天然日光照射下,三唑酮在三种介质中降解较慢.高压汞灯较天然日光能够更有效地激发三唑酮的降解,且降解符合一级动力学规律.在300 W高压汞灯照射下,三唑酮在蒸馏水、人工海水和天然海水中的半寿期分别为54.14 min、144.38 min、177.69 min.三唑酮在蒸馏水中的光降解速率大于其在天然海水中的,这主要是由于天然海水中存在的阴、阳离子和其它特殊的物质所引起的.同蒸馏水中的光反应相比,人工海水中的离子抑制了三唑酮的光降解反应.在500 W高压汞灯照射下,三唑酮的反应速率明显提高.实验发现溶液中加入重金属离子(Cu2+、Pb2+、Cd2+)能够改变三唑酮的光降解速率.     

工业废水排放变化的因素分解与减排效果

在描述中国工业废水排放量、经济增长、经济空间结构和工业废水排放强度的基础上,运用无残差的完全分解模型进行量化分析,分解出1981～2006年间经济增长、空间结构和排放强度对工业废水排放量变化的影响效果,并进一步利用H-P滤波方法对这一时期工业废水减排效果进行了估计.结果表明：① 工业废水排放量年均增长0.25×10⁸　t,其中由经济增长、排放强度、空间结构引起的变化分别为25.9×10⁸　t、 －25.5×10⁸　t、 －0.16×10⁸　t; ② 1981～2006年中国工业废水累计减少排放641.8×10⁸　t,同时受国家宏观经济政策的影响,减排缺口处于波动之中,但总减排缺口大于0,说明实际减排量高于潜在减排量;③ H-P滤波分析所得到的潜在减排率在研究期内呈先上升后下降的趋势;④ 综合来看,我国在1982～1990年及1997～2006年工业发展表现为高污染型,1991～1996年表现为低污染型.     

NOx photocatalytic degradation on active concrete road surface — from experiment to real-scale application

The use of titanium dioxide (TiO₂) as a photocatalyst in concrete pavements has received considerable attention in recent years due to its ability to decontaminate via photocatalytic processes. The objective of this study is to assess the effectiveness of activated concrete road in the degradation of nitrogen oxides (NO_x). We have used a TiO₂ and activated carbon (AC) permeable spray solution to coat concrete to assess its NO_x purifying ability. A number of experiments were undertaken to ascertain the conditions that affect NO_x purification. Indoor simulation experiments with active concrete road at optimum conditions show that it has good purification ability, self-regeneration and repetition ability, with a minimum decontamination rate for NO and NO₂ of 37.4% and 25.84%, respectively. Outdoor experiments show that the photodegradation of NO_x is related to light intensity and temperature. As the light intensity increases the reaction rate increases, and conversely as temperature increases the reaction rate decreases.     

Modeling of the venting of an untempered system under runaway conditions

The prediction of the consequences of a runaway reaction in terms of temperature and pressure evolution in a reactor requires the knowledge of the reaction kinetics, thermodynamics and fluid dynamics inside the vessel during venting. Such phenomena and their interaction are complex and yet to be fully understood, especially reactions where the pressure generation is totally or partially due to the production of permanent gases (gassy or hybrid systems). Moreover, these phenomena cannot be easily determined by laboratory scale experiments. In this paper, a dynamic model developed to simulate the behavior of an untempered reacting mixture during venting is presented. The model provides the temperature, pressure and mass inventory profiles before and during venting. A sensitivity study of the model was performed. This modeling work provides some insight regarding the interpretation of the data obtained from untempered system venting experiments. The outcome of this work contribute to improving the design of emergency relief systems for hybrid and gassy systems, where significant progress is still to be made in the experimental and modeling areas.