Atomization, test atmospheres

Laskin-Type Nozzle Generator. A third type of atomizer, the Laskin-type nozzle generator, is used to create test atmospheres of particulate or aerosol and vapor mixtures. A pure liquid or melt is used, and no solvent is necessary. Again, this is important for evaluating filter and solid sorbent combination sampling trains. 

The background of the concurrent development of the two microprobes that were realized in the United States and France is interesting. The NBS system was developed under funding by the U.S. Air Force whose motivation was to follow the chemistry of radioactive microparticles released into the atmosphere by the atomic tests of the 1950s. Hirschfeld [63] pointed out that only a Raman microprobe could provide the information on chemical speciation necessary to understand the environmental fate of these materials. In France, the group in Lille, under the direction of Professor Michel Delhaye, was creating a molecular microprobe that would provide chemical information complementary to that provided by Castaing s (elemental) electron microprobe. 

The gross flux of carbon from atmosphere to ocean is thus ca. 80 Pg C/yr. There are several complications with the above calculation. The isotopic ratios must be steady-state values, which are unavailable due to the changes resulting from atmospheric atom bomb testing. The few available pre-bomb measurements from the late 1950s (Broecker et ah, 1960) together with determinations in corals (Druffel and Linick, 1978) are invaluable tools for determin-... 

Reference materials for radioisotopes have mainly been used for purposes relating to nuclear and radiation safety. Historically, the development of such materials first arose from the need to assess the risk to human populations caused by worldwide contamination of food and the environment as a consequence of atomic bomb testing - particularly from bombs exploded in the atmosphere. Even now, although atmospheric testing ceased many years ago, the residues from these tests still remain the main source of radionuclides such as Cs and °Sr in the global environment (though locally, other sources may be more important in some countries). 

The catalytic tests were carried out in a fixed bed micro-reactor at atmospheric pressure at 540 °C. The feed composition was 2.5 vol.% of propane, 5 vol. % of ammonia and 5 vol.% of oxygen. The weight of catalyst in the reactor was varied in order to keep the number of Fe ions in the reactor constant (9 pmol of Fe atoms). Conversion, selectivity and yields were calculated on the basis of mass balance in dependence on the time of stream. 

In summary, reactions (43a)-(45) have generally been taken to represent the chemistry occurring in the ozone hole. However, reduced efficiency of chlorine atom production in the photolysis of (C10)2, reaction (44), and hence ozone destruction, needs to be modeled and tested against the atmospheric observations. 

The test consists of exposing bare, fully-loaded fuzes to a salt spray (fog) atmosphere of a special chamber, continuously, for 48 hrs to check operability, and-96 hrs to check safety. The equipment of chamber includes an internal salt soln (20 parts of NaCl in 80 ps of w) reservoir, two or more atomizing... 

Table I. Total atmospheric release of long-tired dose-relevant fission radioisotopes and actinides from the atomic bomb tests and the Chernobyl reactor explosion...

Table 4. Calculated fractious of U7Cs and wSr in Swiss soil samples contaminated by fallout from previous (40 years agoI atmospheric atomic bomb testing I component AI and from the 1986 Chernobyl accident (component C) (reference date I January 20031... 

The nuclear testing which took place in the 1950 s added an estimated 25 X 1027 14C atoms to the atmosphere (27). Although this represents only a small increment to the total 14C inventory of the world, it produced a significant perturbation on the prevailing 14C levels of the atmosphere since the latter contains only a small fraction, ca. 2%, of the total 14C reservoir. Thus, by 1961 atmospheric C02 in the northern troposphere was 25% above the pre-1950 level of 14C. 

Table I shows our estimate of the situation which prevailed in the various carbon reservoirs in the pre-nuclear era and at the end of 1962. The 1961-1962 tests contributed an additional -— 35 X 1027 14C atoms into the atmosphere, principally the stratosphere. These atoms therefore...

C reaches the Earth s surface at the rate of 2.3 atoms/cm2/s after production by cosmic ray interaction in the atmosphere, corresponding to a total production of 1.4 x 1015Bq/y. 14C is also formed by the 14N(n, p) reaction by atmospheric tests of nuclear weapons. About 2.2 x 1017 Bq were made in the atmospheric test spike of the 1950s and 1960s that has been primarily transferred to the oceans and the biosphere. This means that 14C is the most significant fallout nuclide from the point of view of population dose. Nuclear power plants also release 14C as part of their normal operation contributing 0.1 x 1015 Bq/y. 

---