A semiautomated procedure for the determination of phosphorus in water, waste waters and particulates

Improved procedures for the determination of total dissolved phosphorus (TDP), particulate phosphorus (PP) and dissolved inorganic orthophosphate (DP) are described. Organic particulate material is solubilized in 5 n NaOH, and phosphorus compounds are oxidized and mineralized to orthophosphate by persulfate digestion. DP is determined by an improved automated molybdenum blue procedure that does not require sample pH adjustment or a correction for silicate interference in the 0–50 mg Si 1^?1 range. The use of 36-position digestion racks allows 32 TDP or PP samples to be digested in ca. 1 and 4 h respectively. Detection limits in μg of phosphorus 1^?1 are DP, 2; TDP, 5; and PP. 1. Waste water samples were analyzed for TDP and PP by the nitric acid-sulfuric acid procedure and by the proposed method. There was no significant difference between the two sets of data (P > 0.45).     

Interaction effects of multiple pool fires

What are the effects of flame behavior of a number of fires burning in close proximity to one another? The results of measurements of burning rates, heat feedback, flame height, and flame trailing are reported for fires involving liquid pools.     

Studies on oxidation of benzo [a] pyrene by sunlight and ozone

The destruction of the carcinogen benzo[a]pyrene (BaP) by light is well known; laboratory workers are routinely advised to cover fluorescent lamps with yellow filters while treating samples containing BaP. However until recently the mechanism of oxidation by sunlight and ozone had not been studied in detail. Concentrations of benzo[a]pyrene in urban air are in the range of 5–10 μg/1000 m³. Oxidant concentrations (predominantly in the form of ozone) are reported to be in the range of 0.01 ppm (22 μg per m³). Thus a sampling system with a filter paper would filter about 22,000 μg of ozone passing through and collect about 5 μg of BaP for analysis. The effect of interactions of such large ozone concentrations with BaP deposited on the filter paper is reported; data for the oxidation rates for benzo[a]pyrene coated on quartz surface and exposed to ozone or sunlight are presented. The oxidation products were analysed by thin-layer chromatography and highpressure liquid chromatography. From about eight products detected in these experiments, three have been identified as quinones based on UV-absorption spectrometry and mass spectrometry. Oxidation rates as high as 100% per hour of exposure are observed when less than 0.1 μg of BaP is coated inside the quartz tubes and exposed to ozone or sunlight. Oxidation rates for benzo[a]pyrene (using tritiated BaP) were determined for two types of experimental conditions. In the first set, tritiated BaP was spotted onto a glass fibre paper and sampling continued for 24 h; the loss of BaP was found to be 88%. In the second set tritiated BaP was spotted at intervals of one hour, for eight hours, while sampling is being carried out and the loss of BaP during the period was estimated to be 50%.     

A digital wind gust recorder

The instrument was a byproduct of an undergraduate final year project on wind power which was carried out by the Department of Mechanical Engineering of the University of Liverpool.The windmill test site was on an exposed, rocky island where there was no history of weather recording but a long tradition of violent winds.Field experience during the winter months suggested that corrosion fatigue arising from wind buffeting and salt spray would rank equally with maximum wind pressure as criteria of failure and if modern materials, so convenient for forming aerodynamic surfaces, were to be used then limited life concepts would need to be considered. This called for more knowledge of wind variations at the test site. A complete wind spectrum taken on chart recording instruments would have been ideal but since such such refined devices were not available the instrument to be described was designed.The only wind measuring instrument which was available was a rotating cup anemometer. This supplied an alternating voltage proportional to its rotational speed. It also operated a gear driven microswitch which could give an integrated “miles of wind” reading on an electromagnetic counter.Briefly the e.m.f. generated by the anemometer (Fig. 1) was matched against a pre-set voltage corresponding to the required gust velocity. When this was exceeded an appropriate counter was operated. Only the rising e.m.f. was significant. The subsequent fall was ignored. Initially three stages were incorporated which reported the gusts rising through forty, fifty and sixty knots, respectively. These recorded on separate counters. All basic settings were based on pitot-static speed determinations in a wind tunnel.     

Combined biological and ozone treatment of log yard run-off

Batch biological treatment of log yard run-off reduced biochemical oxygen demand (BOD), chemical oxygen demand (COD) and tannin and lignin (TL) concentration by 99%, 80%, and 90%, respectively. Acute (Microtox) toxicity was decreased over treatment, from an initial EC50 of 1.83% to a value of 50.4% after 48 h of treatment. Kinetics of biodegradation were determined using respirometry and fitted using the Monod and Tessier model. For the Monod model the maximum substrate uptake rate, and Ks values determined were 0.0038 mg BOD/mgVSS min, and 1.4 mg/L, respectively. The efficacy of ozone as a pre- and post- biological treatment stage was also assessed. During ozone pretreatment, TL concentration and acute toxicity were rapidly reduced by 70% and 71%, respectively. Pre-ozonation reduced BOD and COD concentration by < 10%, however a larger fraction of residual COD was non biodegradable after ozonation. Biologically treated effluent was subjected to ozonation to determine whether further improvements in effluent quality could be achieved. A reduction in COD and TL concentration was observed during ozonation, however no further improvement in toxicity was observed. Ozonation increased BOD by 38%, due to conversion of COD to BOD.     

Seismic methods for study of soil building properties

Bulletin of Engineering Geology and the Environment - Information about distribution of elastic wave propagation velocities Vp, Vs in the subsurface zone of a soil mass can be obtained rapidly and...     

Long-term geophysical observations on the inguri dam rock foundation

Bulletin of Engineering Geology and the Environment - It has been found that during construction of the dam, prior to the filling of the reservoir, compaction and loading of the rocks under the...     

The bacterial population of piggery-waste anaerobic digesters

A survey was made of the anaerobic and facultatively anaerobic bacteria present in piggery waste, digesting piggery waste and domestic anaerobic sludge sludge used to start a piggery waste digester. An influence of the input waste was shown in that streptococci, the predominant facultatively anaerobic bacteria in the piggery waste, were the predominant bacteria in the digesting waste, and they replaced Enterobacter, predominant in the domestic sludge, when a piggery waste digestion had been established from this latter material. Cellulolytic or methanogenic bacteria could not be detected in the piggery waste but populations of these, and other hydrolytic bacteria, became established at different times during the buildup of digestion by gradual addition of piggery waste to water. The bacteria concerned in degradation of the waste constituents were all anaerobes.Production of methane from H₂/CO₂, formate and butyrate could be detected in mixed cultures from dilutions of digester contents, but the only methanogenic bacterium that could be isolated in pure culture was Methanobacterium formicicum, which uses H₂/CO₂ or formate only.     

A quadratic complementarity problem related to the optimal design of a pipeline freely resting on a rough sea bottom

A submarine pipeline resting on a rigid, frictionless seabed assumes an equilibrium configuration which can be determined by solving a unilateral contact problem, i.e. a quadratic program or a variational inequality.When the sea bed is irregular, its profile along the sealine can be modified, in present offshore technology, by means of costly trench excavations or artificial supports, in order to avoid excessive bending moments in the pipe. Thus, the problem arises of determining the minimum cost of the profile changes provided that a specified curvature is nowhere exceeded.This optimal design problem is solved by assuming a quadratic cost function and reducing it to a sequence of convex quadratic programming problems leading to the optimal design situation. Upper and lower bounds on the absolute minimum cost and optimality conditions are established. A suitable algorithm for solving the problem in a finite number of steps is developed. Its generalization to allow for ‘fixed charges’ due to the equipment mobilization cost is presented. Two numerical examples illustrate the optimum (minimum cost) proposed design method.     

以美国景观设计市场化经营为鉴,审视中国的发展

加利福尼亚作为美国自然环境多样化和文化多元的地区,景观设计在历史上形成了独具特色的风格.在二战以后社会变革和产业复兴中,景观设计学在私营领域得到了巨大发展,涌现了大量的事务所.通过介绍笔者在加州的实践二例,并从多学科合作的设计方法、与不同主体的沟通策略、发展开放空间以及城市复兴的经济和社会考虑等多个方面,阐述了景观设计的意义,并强调私营部门的积极作用,以期对中国的景观设计学发展有所助益.