Determination of Selenium in the Smoke from Trash Burning
Abstract The smoke resulting from open trash burning operations was analyzed for its selenium content. Selenium (as its oxides) was efficiently trapped by impingement into distilled water and determined by a methylene blue catalytic method. The data obtained show a relationship between the selenium content of the smoke and the burning material. Concentrations as high as 273 μg/m3 of selenium dioxide were found when dry wood chips were burned. The reaction of selenium oxides in humid atmospheres and in the moist tissues of the respiratory tract forms selenic or selenious acids and must be regarded as a definite health hazard.
Abstract Many human operations have created a large population of small orbital debris in near Earth environment. The threat they represent for satellites is a major factor for the preparation of future space missions. Several experiments devoted to the study of this environment, as well as various materials exposed to space, have been retrieved in the past few years. The analysis of the results shows some differences with previous modeling. Comparison with data from LDEF and from EURECA give some insight in the long term evolution of particle size distribution. Chemical identification of particle remnants inside craters is difficult but provides valuable information on the origin of the impactors. Permanent monitoring of environment is obviously needed, especially for the type of orbits where data are presently scarce ie. heliosynchronous and geostationary orbits.