Site Location Conclusions

To summarize the conclusions from the foregoing data, which of course are not sufficient for broad generalizations, we found that the additivity principle predicts reactivities of a correct order of magnitude for 1,2-disubstituted and 1,3,5-trisubstituted compounds. In general, the observed reactivities were somewhat lower than the predicted ones, with the exception of sites located para or ortho to a phenolic hydroxyl adjacent... 

Second, generic and site-specific assessments of near-surface disposal facilities for radioactive waste have shown that allowable doses to hypothetical inadvertent intruders usually are more restrictive in determining acceptable disposals than allowable doses to individuals beyond the boundary of the disposal site. This conclusion is based on predictions that concentrations of radionuclides in the environment (e.g., ground-water) at locations beyond the site boundary usually should be far less than the concentrations at the disposal site to which an inadvertent intruder could be exposed, owing to such factors as the limited solubility of some radionuclides, the partitioning of radionuclides between liquid and solid phases, and the dilution in transport of radionuclides in water or air beyond the site boundary. More people are likely to be exposed beyond the site boundary than on the disposal site, but acceptable disposals of radioactive waste in near-surface facilities have been based on assessments of dose to individuals, rather than populations. 

From the previous discussion, it follows that the intracrystalline volume in zeolites is accessible only to those molecules whose size and shape permits sorption through the entry pores thus, a highly selective form of catalysis, based on sieving effects, is possible. Weisz and coworkers 7) have conclusively established that the locus of catalytic activity is within the intracrystalline pores when Linde 5A sieve ( 5 A pore diameter) was used, selective cracking of linear paraffins, but not branched paraffins, was observed. Furthermore, isoparaffin products were essentially absent. With the same catalyst, -butanol, but not isobutanol, was smoothly dehydrated at 230-260°. At very high temperatures, slight conversion of the excluded branched alcohol was observed, suggesting catalysis by a small number of active sites located at the exterior surface. Similar selectivity between adsorption of n-paraffins and branched-chain or aromatic hydrocarbons is shown by chabazite and erionite (18). 

A combination of measurements and simulations have indicated that cloudwater sulfate, acidity, nitrate, and ammonium deposition exceeds wet deposition via precipitation for some NE U.S. sites located above 400 m. While the current large uncertainties that are associated with cloudwater deposition models make firm estimates impossible, the available data indicate that cloudwater deposition is a substantial contributor to wet deposition inputs to high elevation sites in the eastern United States. Similar conclusions have been reached by European studies. 

Since samples from sites 2, 3, and 6 are overlapped, it can be said that these three sites give the same water, as is the case of sites 1 and 5. The water from sites 4 and 7, instead, is rather "specific" of that single site and different from that of the other sites (these conclusions are in agreement with the geographical location of the sites). 

The slowest rate of aflatoxin decomposition occurred in the silty clay loam soil. At the conclusion of the study (120 days), only 1.4% of the aflatoxin had been released as C02 The greatly reduced rate of C02 release probably resulted from the binding of aflatoxin to the exchange sites of the soil, especially those sites located on clay. The soil does have a relatively high clay content and this could potentially adsorb the aflatoxin or its degradation products. Masimango et al. (1979) demonstrated that aflatoxin could be bound very tightly to clay. Hence, considerable evidence exists that the adsorption of aflatoxin to clay may also have been responsible for the reduced rate of decomposition. 

The Ru surface is one of the simplest known, but, like virtually all surfaces, it includes defects, evident as a step in figure C2.7.6. The observations show that the sites where the NO dissociates (active sites) are such steps. The evidence for this conclusion is the locations of the N and O atoms there are gradients in the surface concentrations of these elements, indicating that the transport (diffusion) of the O atoms is more rapid than that of the N atoms thus, the slow-moving N atoms are markers for the sites where the dissociation reaction must have occurred, where their surface concentrations are highest. 

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