Environmental letters最新文献

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.

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.

A uniform approach to quantitation of environmental PCB residues was sought. There exists a requirement for a reasonable compromise between accurate analysis and the ability to handle large numbers of samples. An international survey of electron-capture gas chromatographic methods utilized by laboratories currently analyzing for PCB was conducted from the Canada Centre for Inland Waters. Subsequent evaluation of the methods received has led to adoption of a uniform basic procedure which fulfils the objectives and demonstrates a wide general applicability.

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.

Possible environmental effects and the importance of charged aerosol particles are examined. Some calculations of the evolution of the charge distribution of the atmospheric aerosol are presented. Several possible environmental effects of particle charge are noted including effects on particle coagulation, dry deposition, and deposition in the lung. Finally some problems in aerosol charging are reviewed as they pertain to various technical operations in air pollution control.

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.

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.

Cultures of Gonyaulax tamarensis were grown on Hastings medium based on 100%, 10%, 1%, 0.1% and 0% (control) of seawater elutrients of bottom sediments. Both "clean" and heavily polluted sediments were used. Very low concentrations of polluted elutrients (0.01% v/v) slightly enhanced the growth of Gonvaulax tamarensis; greater concentrations of polluted elutrient depressed growth. Elutrient from "clean" sediments did not enhance growth; the depression of growth at any given elutrient concentrate was not as great as that seen with the polluted elutrients.

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.