Organochlorine insecticides and PCB'S in sediments of Lake St. Claire (1970 and 1974) and Lake Erie (1971).

Sediments were collected on a grid from Lake St. Clair in 1970 and 1974 and from Lake Erie in 1971 and analysed for organochlorine insecticides and PCBs. Suspended solids were centrifuged from pumped water in the Detroit River in 1974. Residues of DDE, TDE and DDT were highest in sediment from the Western Basin (70.3 ppb) Lake Erie and lowest in sediment from Lake St. Clair (6.6 ppb in 1970 and 2.6 ppb in 1974). The Central and Eastern Basins of Lake Erie contained residues that fell about mid-way between these means. TDE was the predominant component of ΣDDT and was followed by DDE at approximately half this residue. While DDT represented the lowest component in lake sediments, it was the highest component in suspended solids from the Detroit River.HEOD was present in the entire lake system but at only a fraction of the level of ΣDDT. The mean residue in Lake St. Clair was only 0.1 ppb while Lake Erie sediments contained 1–2 ppb. The highest mean residue (3.6 ppb) was in suspended solids in the Detroit River. Other organochlorine insecticides were only occasionally identified.PCB residues in sediment were approximately 3 times higher than the total organochlorine insecticide residue, being highest in the Western Basin (252 ppb) and lowest in Lake St. Clair (19 ppb in 1970 and 10 ppb in 1974). The Detroit River and Central and Eastern Basins of Lake Erie had intermediate residues.Residues in Lake St. Clair indicated a decline in ΣDDT, HEOD, and PCB residues between 1970 and 1974, and this coincided with the restrictions on the materials. A core sample from the Western Basin of Lake Erie indicated that ΣDDT, HEOD and PCB began to accumulate in sediments in 1958, 1953, and 1956, respectively. This appeared to indicate a lag period of 2–5 years after wide-spread use occurred.     

A new mathematical model to evaluate simazine removal in three different immobilized-biomass reactors

A new mathematical model based on the cinetical Langmuir equation is developed to interpret and predict the effectiveness of simazine (SZ) removal in immobilized-biomass reactor (IBR), to consider herbicide-support affinity (Cx), and herbicide-cell affinity (Cy). Three solid supports: sepiolite monolith, granular sepiolite, and alginate were used in pilot-scale reactors that were inoculated with Klebsiella planticola DSZ. The abiotic process was analysed by measuring the SZ sorption capacity of the reactor supports. Sepiolite monolith showed the maximum value for herbicide-support affinity (28.02+/-0.9%). The effectiveness of the biotic process was estimated considering the formation of biomass and SZ biodegradation. Granular sepiolite showed either higher affinity with SZ and viability rate (0.90) throughout the process, and SZ removal rate was 3.39+/-0.06 mg/h. The mathematical model presented in this paper provides useful insights into the interpretation of experimental data as well as prediction for the implementation of biological reactors.     

Extreme wind speeds in mixed wind climates

In this paper, a technique is discussed which enables extreme wind speed probabilities in mixed wind climates to be determined. It is shown that in such wind climates the method is likely to yield more accurate probability estimates than the traditional Gumbel analysis of annual wind speed maxima, particularly for annual probabilities of less than 2% (i.e. return periods greater than 50 years). The technique requires a separate analysis of each significant wind-producing meteorological phenomenon and practical methods of achieving this are presented. Extreme wind speed parameters obtained from each analysis may then be combined to yield a “composite extreme wind speed diagram” and several examples illustrating this procedure are shown. By means of a numerical simulation of a typical mixed wind climate, a detailed study is made of the distribution of extreme wind gusts from different meteorological phenomena. This study indicates that a Gumbel analysis of 20 annual maxima may severely underestimate low annual probability (i.e. long return period) gust speeds.     

The demographics and politics of economic decline in New York City

New York City's economy has been declining since 1969. Although this decline is usually discussed with reference to interregional shifts in population and the migration of industry to the South and West, the root causes can be best understood in terms of the changing demographic, political and economic matrix of the City combined with short-sighted public policies toward business development.After explaining some important aspects of the political economy of economic erosion in New York City, the paper suggests several local government policy alternatives that might help to reverse the tide of economic decline.     

The effect of depositional history on contaminated bed sediment stability

Experiments were conducted in an annular flume using a commercially available kaolinite clay as well as contaminated bed sediment from Hamilton Harbour (Ontario) to assess their stability against erosion. Critical shear stress for erosion was measured under different conditions of bed formation (quiescently deposited beds and shear deposited beds) as well as with and without the presence of a biostabilized bed. Results suggest that a biostabilized bed and a bed formed under a flowing condition, similar to a river scenario, will be more resistant against erosion than will a non-biostabilized bed and a bed formed under quiescent conditions. Up to three cycles of erosion and flocculation/deposition were observed to occur within one experiment. These results suggest that the depositional history and biostabilization of river bed sediments need to be seriously considered within sediment and contaminant transport models if meaningful estimates of sediment and contaminant source, fate and effect are to be generated and used for the management of our aquatic ecosystems.     

鞍形索网玻璃采光屋面的应用与设计

结合一项实验工程对鞍形索网结构在玻璃采光屋面中的应用及其受力特性进行研究 ,同时对施工过程进行模拟分析。为鞍形索网体系在玻璃采光屋面中的应用和设计提供了建议。     

The impact of preoxidation of SAS on biosorption efficiency on activated carbon

We have studied the process of a prolonged dynamic filtration on activated carbon in two biosorption systems — without preoxidation treatment of the initial matter and after ozonization. It has been shown that given the uniform load on activated carbon terms of the organic matter the efficiency of the biosorption process after preozonization is 2.3 times as small compared with that that without pretreatment, which correlates with the change of adsorption free energy.     

Engineering geology today

Summary The author discusses the development and present state of the engineering geology. He warns the engineering geologists against a merely mechanical approach and emphasizes that an engineer needs to understand geology as well. Further an analysis of the relation between geology and civil engineering and between engineering geology and soil and rock mechanics is presented. Finally the paper deals with the tasks of engineering geology at designing and construction of structures as well as with the problems of education in engineering geology.

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La Géologie De l’Ingénieur Aujourd’Hui

Résumé L’auteur examine la question du développement et de la situation acutelle de la géologie de l’ingénieur. II préviend d’un accès simplement méchanical en accentuant, qu’il est vraiement nécéssaire pour un ingénieur de comprendre aussi la géologie. Puis, l’auteur analyse la rélation entre la géologie et la construction ainsi qu’entre la géologie de l’ingénieur et la mécanique du sol. Enfin, le travail traits les taches de la géologie de l’ingénieur dans la sphère des projets et de la réalisation des constructions ainsi que les problèmes de l’éducation.

     

“重点受控”与“局部放任”─—山地城市设计方法研究之一

本文试图找到一种可操作的城市设计方法。以山地城市形态为切入点，辩证地应用重点论和两点论，对山地城市形态的重点要素进行重点控制，而对非重点要素采取引导性设计。