Environmental letters最新文献

Water is polluted when it constitutes a health hazard or when its usefulness is impaired. The major sources of water pollution are municipal, manufacturing, mining, steam, electric power, cooling and agricultural. Municipal or sewage pollution forms a greater part of the man's activity and it is the immediate need of even smaller communities of today to combat sewage pollution. It is needless to stress that if an economic balance of the many varied services which a stream or a body of water is called upon to render is balanced and taken into consideration one could think of ending up in a wise management programme. In order to eliminate the existing water pollutional levels of the natural water one has to think of preventive and treatment methods. Of the various conventional and non-conventional methods of sewage treatment known today, in India, where the economic problems are complex, the waste stabilization ponds have become popular over the last two decades to let Public Health Engineers use them with confidence as a simple and reliable means of treatment of sewage and certain industrial wastes, at a fraction of the cost of conventional waste treatment plants used hitherto. A waste stabilization pond makes use of natural purification processes involved in an ecosystem through the regulating of such processes. The term "waste stabilization pond" in its simplest form is applied to a body of water, artificial or natural, employed with the intention of retaining sewage or organic waste waters until the wastes are rendered stable and inoffensive for discharge into receiving waters or on land, through physical, chemical and biological processes commonly referred to as "self-purification" and involving the symbiotic action of algae and bacteria under the influence of sunlight and air. Organic matter contained in the waste is stabilized and converted in the pond into more stable matter in the form of algal cells which find their way into the effluent and hence the term "stabilization pond".

This paper reviews some of the questions that have been asked by experts and others as to why nuclear power plants are not located or placed underground. While the safeguards and present designs make such installations unnecessary, there are some definite advantages that warrant the additional cost involved. First of all, such an arrangement does satisfy the psychological concern of a number of people and, in so doing, might gain the acceptance of the public so that such plants could be constructed in urban areas of load centers. The results of these studies are presented and some of the requirements necessary for underground installations described, including rock conditions, depth of facilities, and economics.

The polarization ratio method similar to that proposed by Kirker et al. has been applied to obtain size distribution for several types of metallic smoke particulates generated by a dc electric arc. Results are presented for carbon, tungsten and aluminum arc smokes. These results are compared with the average size of the particulates measured by the two-angle ratio method of Hodkinson and are found to be consistent and within experimental error. The optical system was calibrated with standard latex spheres in both cases. It is believed that the parameters of the arc smoke particulate systems should be useful for environmental particulate research.

Studies conducted in smog chambers show that ozone disappears significantly faster under irradiation than in the dark. A computer simulation was made to determine the cause for this accelerated O3 decay. It was found that the phenomenon can be explained by a series of chemical reactions involving O3, O1D, H2O, OH, HO2, and ultraviolet light.

Fog from cooling towers causes problems of visibility and icing along roadways adjacent to the towers; moreover, the visible plume from the towers offers difficulty in that it is equated by much of the public with air pollution. It is desirable to know the size of the fog droplets in order to plan abatement procedures and to determine the airborne lifetimes of such fogs. The methodology involved capturing the droplets on slides coated with a vaseline-mineral oil mixture, making photomicrographs of the droplets, counting and sizing the droplets into eight droplet diameter increments; namely less than 5 mum, 5-10 mum, 10-20 mum, 20-40 mum, 40-60 mum, 60-80 mum, 80-100 mum, and greater than 100 mum. The resulting distribution was similar to that for natural fogs and clouds; i.e., it was bi-modal, the first mode at less than 5 mum containing the vast majority of the droplets, and the second at 20-40 mum. This study agrees with others that the size distribution of a fog in a saturated environment is continuously changing, with the smaller droplets tending to evaporate and the larger ones tending to grow, thus shifting the second mode toward larger sizes.

Lobsters are able to feed on shellfish which are toxic with PSP (paralytic shellfish poisoning from Gonyaulax tamarensis) with no apparent harm to themselves, and no measurable assimilation of the poison into their tissues. Lobsters consumed food containing in excess of 1000 mug PSP. There was no impairment of respiration (oxygen consumption) measurable two to three hours after feeding, and no PSP measured in the meat of the claws and tail 48 to 120 hours after feeding. The only PSP was in the guts and contents which were measured 48 hours after feeding began.

This paper describes the waste processing and boiler feed facilities which serve as the prototype for Union Electric Company's proposed Solid Waste Utilization System for recycling essentially all the solid waste generated in the metropolitan St. Louis area. The recently announced system, capable of processing up to 8,000 tons of raw refuse per day and estimated to cost $70 million, will be built and operated without government subsidy. Solid waste will be processed for the recovery of recyclable noncombustibles and use as a supplementary fuel to electric utility boilers.

The use of stable, activable tracers has been studied in applications to establish the performance of waste treatment plants and detect causes of irregular or improper functioning of individual plant processes. Various soluble tracers were evaluated, among them indium, scandium, and bromine. The inert tracers were compared with dye tracers and were found to be superior in turbid liquids and to give more quantitative information. On the other hand dye tracers are more convenient for rapid visible indication of their arrival whereas activable tracers require collection and removal to a neutron source, such as a reactor, for indication. Activable tracers are relatively simple to apply and the cost per test is reasonable.

This paper describes a confirmation procedure for residue levels of dyfonate, dichlorofenthion and cyanox. After extraction and quantitation by flame photometric detector (FPD)-gas liquid chromatography (GLC), the organophosphorus pesticides are hydrolyzed in a 10% methanolic-potassium hydroxide solution. The phenolic hydrolysis products are then extracted from this solution and reacted with pentafluorobenzyl bromide to produce the pentafluorobenzyl (PFB) ether derivatives. These PFB ethers are subsequently cleaned-up and fractionated on a silica gel micro-column and analyzed by electron capture (EC)- GLC.