乐安江沉积物酸碱特性及其对重金属释放特性的影响

本文对乐安江沉积物样品的金属总量、酸碱特性进行了测定和不同pH条件下金属的释放实验.结果表明,乐安江沉积物中Cu,Pb,Zn,Cd和As的浓度均高于一般水体沉积物的本底值.从重金属的移动性分析,存在沉积物重金属对水体产生二次污染的可能.沉积物所含重金属随pH变化产生的金属释放顺序是Zn>Cu>Cd.Pb.     

CHANGE IN LAKE TROPHIC STATE AND INTERNAL PHOSPHORUS RELEASE AFTER ALUMINUM SULFATE APPLICATION1

ABSTRACT: Recovery of eutrophic lakes after nutrient diversion may be delayed if the lake experiences significant internal phosphorus (p) loading to the water column. A maximum dose of aluminum sulfate, defined herein, was applied to the anaerobic sediments of the hypolimnia of two dimictic Ohio lakes following septic tank diversion, with the objective of attaining long term control of the release of phosphorus to the water column from these sediments. The results were compared to a similar, downstream, untreated lake. Total phosphorus concentration declined sharply after treatment and has remained so through 1980 for both lakes, a period of 5 and 6 years of control, respectively. Internal P loading from anaerobic, hypolimnetic sediments was partially controlled by the treatment but there are other important sources, perhaps in the littoral zone, in these lakes. Algal biomass is Smaller and water transparency has increased. Both lakes became mesotrophic after treatment, as described by the Carlson (1977) trophic state index, and remain in that improved condition to date. No deleterious side effects were observed, although one lake experienced a significant decrease in diversity of planktonic microcrustacea and a lakeward extension of the macrophyte community. This method appears to be an effective and lasting means of accelerating the recovery of a eutrophic lake following nutrient diversion.     

设计火灾时火灾热释放速率曲线的确定

在运用火灾计算机模型进行建筑物性能化消防设计与评估时,确定合理、切合实际的火灾的热释放速率曲线非常重要。基于当前国内外的研究现状,本文提出了几种符合当前技术水平且实用的确定火灾热释放速率曲线的方法,对于每种分析计算方法及其适用条件进行了详细阐述,并给出了相关的计算实例。     

Vent sizing for gas-generating runaway reactions

Exothermic runaway reactions that generate non-condensible gas as the temperature increases, as is typical of decompositions for example, can reach extremely high rates of pressure rise necessitating emergency relief of the process vessel containing the reactant. Sizing of a relief device using presently recommended methods (e.g. DIERS) frequently leads to extremely large and expensive vents. This paper presents a methodology that leads to a simple but much improved method for vent sizing, fully allowing for two-phase release of the gas—liquid mixture. A number of examples are presented which lead to interesting conclusions about the influence of plant variables.     

A STOCHASTIC DYNAMIC PROGRAMMING BASED APPROACH TO THE OPERATION OF A MULTI-RESERVOIR SYSTEM1

ABSTRACT: An heuristic iterative technique based upon stochastic dynamic programming is presented for the analysis of the operation of a three reservoir ‘Y’ shaped hydroelectric system. The technique is initiated using historical inflow data for the downstream reservoir. At each iteration the optimal policies for the downstream hydroelectric generating unit are used to provide relative weightings or targets for operation of upstream reservoirs. New input inflows to the downstream reservoir are then obtained by running the historical streamflow record through the optimal policies for the upstream reservoirs. These flows are then used to develop a new operating policy for the downstream reservoir and hence new targets for the upstream reservoirs. The process is continued until the operating policies for each reservoir provide the same overall system benefit for two successive iterations. Results obtained from the procedure are compared to the results obtained by historical operation of the system. The procedure is shown to develop operating policies which give benefits which are as close to the historical benefits as can be expected given the choice of the number of storage state variables.     

水体中痕量氯苯的气相色谱分析方法研究

根据氯苯在水体中溶解度小，易吹脱且热稳定性好的特点，建立了水体中痕量氯苯的分析方法。该法采用简化的吹脱、捕集装置用ＴｅｎａｘＧＣ富集水体中氯苯，热解吸法浓缩进样，大口径毛细管柱分离，ＦＩＤ测定。方法操作简单、快速，测定水体中氯苯最低检出限为０．４μｇ／Ｌ，相对标准偏差小于８．６％。方法适宜于水体中痕量氯苯的测定     

Monitoring nekton as a bioindicator in shallow estuarine habitats

Long-term monitoring of estuarine nekton has many practical and ecological benefits but efforts are hampered by a lack of standardized sampling procedures. This study provides a rationale for monitoring nekton in shallow (<#60; 1 m), temperate, estuarine habitats and addresses some important issues that arise when developing monitoring protocols. Sampling in seagrass and salt marsh habitats is emphasized due to the susceptibility of each habitat to anthropogenic stress and to the abundant and rich nekton assemblages that each habitat supports. Extensive sampling with quantitative enclosure traps that estimate nekton density is suggested. These gears have a high capture efficiency in most habitats and are small enough (e.g., 1 m²) to permit sampling in specific microhabitats. Other aspects of nekton monitoring are discussed, including spatial and temporal sampling considerations, station selection, sample size estimation, and data collection and analysis. Developing and initiating long-term nekton monitoring programs will help evaluate natural and human-induced changes in estuarine nekton over time and advance our understanding of the interactions between nekton and the dynamic estuarine environment.     

吹气—吸收法测定废水中硫化物

对吹气－吸收法测定废水中硫化物进行了吸收试验，提出了用去离子除氧水配制硫化物标液，可增加其稳定性；用ＩＳＯ硫化物吹脱器取代普通气吸收装置，可提高硫化物回收率。试验结果表明，改进后方法的精密度，准确度及适用怀强垃令人满意。     

东海特定海区沉积物-水界面附近P释放的实验研究

以采自长江口外东海表层沉积物为对象，对不同类型的沉积物在模拟海水环境中进行了释P实验。研究表明，在静态条件下，沉积物释P量的高点出现在摇晃后10min左右，大约3h后基本趋于平衡。释P动力学可用Elovich公式与双常数速率公式进行拟合。最大释P量与沉积物的组成密切相关，以粉砂、粘土为主的沉积物释P量高，而砂质为主者释P量低。在释P实验中，铁磷(Fe-P)最为活跃，释放比例最高，其次是吸附态磷(Ad-P)和有机态磷(OP)。它们均属于生物可获得P的范畴。实验结果表明，在合适的水动力条件下，沉积物中的P可以迅速释放到水体．并影响水体的营养状杰和初级生产力。