社区环境管理取得成果的要素:美国酸性矿物废水治理的经验教训

1980年代,社区环境管理(CBEM:community-based environmental management)作为处理棘手环境问题的创新途径在美国开始出现.CBEM指的是地方团体采用与各类代理机构、地方政府或其他组织以合作方式处理环境问题.为更好地理解这一流行的环境管理手段,本文首先回顾环境管理制度的演变以及影响CBEM过程的资源变化,在此基础上,本文建构了关于CBEM过程的评估框架,并列举了两个通过发起CBEM来治理酸性矿物废水对流域污染的案例.     

Observations on the changes in nitrate concentrations along streams in seven upland moorland catchments in Northeast Scotland

River water has been sampled under baseflow conditions in both summer and winter at c. 250-m intervals along the length of each of seven rivers in northeast Scotland, and the nitrate contents have been determined. The resultant data have been examined in the context of the nitrogen saturation hypothesis. Capacity of the catchment soils to retain nitrate was generally minimal in winter. Although biological uptake of nitrate was evident in summer, in the upper part of each catchment substantial nitrate leaching still occurred. The phenomenon was most marked in water draining from hill peats, except where these were conspicuously waterlogged. The results are discussed in the context of possible nitrogen saturation effects on upper catchment slopes.     

Geomechanical model simulation for the varied rock formations of the Kadana dam foundation,Gujarat, India

Bulletin of Engineering Geology and the Environment - Precambrian layered rocks consisting of quartzites, phyllites and metagreywackes of the Aravallis having a large variation in thickness,...     

The development of macrolayer thickness of water in the pool boiling regime

ABSTRACT

The main purpose of this study is to analyse the phenomenon of pool boiling in water over a horizontally placed copper tube heater of 28?mm diameter. The experiment has been carried out to observe the bubble growth and departure characteristics for the heat flux range up to 40,000?W/m². The entire process is being recorded by a digital camera at different time intervals. The measured parameters have been used to determine the initial layer thickness, macro layer thickness and critical heat flux and validated with models proposed in the literature.     

Orientation of smoke production in polyacrylonitrile

The introduction of ionic additives, such as KCN, or acidic comonomer units, such as methacrylic acid, which change the nature of the mechanism of nitrile oligomerization reaction from radical to ionic and cause its initiation at lower temperature, allows the level of obscurity and the total amount of smoke production, both in smouldering and flaming conditions to be decreased. An opposite result is obtained if diphenylpicrylhydrayl (DPPH) radicals in polyacrylonitrile is introduced; DPPH retards the initiation of the radical nitrile oligomerization reaction. The acrylonitrile-methacrylic acid copolymers have a limiting oxygen index, which increases with the methacrylic acid content. Owing to the increased amount of NH₃ produced during pyrolysis, the copolymers have a swelling behavior during the combustion test.     

Results of evaluation of the strength of concrete placed in the shafts of cast-in-place piles

Conclusions 1. Application of the method of underwater concreting with the use of a container is inexpedient in connection with the presence of a large number of flaws detected in the shafts of cast-in-place piles formed by this method; concreting of holes by the VAT method is preferable.2. The strength of concrete in the shafts of cast-in-place piles increases, reaching a maximum at a depth of 0.4–0.5 the length of the shaft. Variation in strength along the shaft is explained primarily by the percentage of coarse aggregate contained in the concrete.3. The quality of pile concrete should be monitored during all stages of pile installation, and, primarily during the stage of concreting, i.e., when there is a chance of correcting an observed defect.All-Union Institute for the Design and Planning of Health Resorts. Scientific-Research Institute of Foundations and Underground Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 14–17, September–October, 1976.     

A colorimetric method for ammonia in natural waters

An improved phenol-hypochlorite method for determining ammonia in water using nitroprusside as catalyst has been investigated. Unlike other recently published methods, the method is simple (and sufficiently sensitive for low-level analyses) and does not require accurate time intervals between reagents, not expensive equipment. The method is well suited for routine use.

Beer's Law was obeyed over the whole ammonia range investigated. Reproducibility was 1·3 per cent with 10 μg N, and 5·7 per cent with 1 μg N.     

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%.