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In 1975, archeological surface surveys of trade routes located again a pre-Hispanic obsidian source in central Mexico first reported in 1902. Initial trace element studies of the Paredón source through an analysis by neutron activation have been compared with similar studies of the obsidian found at Chalcatzingo 150 kilometers from the source. These comparisons indicate that obsidian from Paredón, rather than Otumba, was of primary importance during the Early Formative in central Mexico.

The adsorption and desorption of radon on five types of activated carbon and the effect of various airborne contaminants on the adsorption process was studied, the dynamic adsorption coefficient for the carbon samples tested was found to range from 2.4 +/- 0.2 to 7.1 +/- 0.71 g-1. Iso-octane was found to reduce the dynamic adsorption coefficient significantly.

The decay of 222Rn produces a positively charged 218Po ion 88% of the time. The electrostatic collection of this ion has served as the basis of a number of systems for measuring Rn concentrations. However, there are neutralization processes that restrict the time available to collect the ion. The measured rates of neutralization by water vapor and by trace gases have been used to determine the applied field strengths necessary to ensure complete collection of the ions and thus interference-free Rn determinations.

Wire screens are commonly used to estimate "unattached" Rn daughter fractions in ambient and mine atmospheres. However, it is now recognized that the "unattached" fraction is in reality an ultrafine cluster mode in the 0.5-3 nm size range and that the collection efficiency versus particle diameter characteristics of wire screens do not permit a distinct separation of the "unattached" and "attached" fractions. Wire screen penetration theory and a semi-empirically corrected diffusion coefficient equation are used to characterize "unattached" fraction measurements as a function of experimental parameters. Collection efficiency curves are estimated for previously published wire screen "unattached" fraction measurements, and improvements in wire screen methods for such measurements are discussed.

Different multivariate methods have been applied to obtain an overview of the Belgian female cancer mortality distribution. The resulting maps and figures show the patterns of female cancer mortality to be strongly geographically determined. Two major trends can be derived namely along the north-south axis and along the east-west axis of the country. The cancer sites responsible for these patterns are identified.

The disposal of complex mixtures such as wastewater on agricultural lands poses known and unknown environmental risks. Mutagens may be introduced into the ecosystem and perhaps concentrated by crop plants or leached into ground water supplies. The purpose of this study was to determine the biological effect of a mutagenic wastewater before and after application to soil. An XAD-8 methanol extract of wastewater from the municipal sewage treatment facility at Sauget, IL, was a potent, direct acting mutagen when assayed with Salmonella typhimurium. One and 3 ml of extract were brought up to 10 ml volumes with water and added to 10 g of sterile or nonsterile native clay loan. These mixtures were incubated at room temperature for 0, 24 and 48 h. After separation of solid and liquid portions by filtration, dichloromethane was added to extract the organic fractions from each component. Solvent extractions were evaporated to dryness under vacuum and brought up in DMSO. Tests for mutagenic activity were conducted using Ames strain TA98. Addition to the soil for greater periods of time decreased the mutagenic activity. The solid component exhibited greater mutagenic activity than the liquid.

The two-filter method described by Thomas and LeClare was used to investigate the effects of trace concentrations of nitric oxide and nitrogen dioxide in dry nitrogen on the diffusion coefficient of radium A (polonium-218). Charged radium A was neutralized in 10 parts per million (ppm) nitrogen dioxide in dry nitrogen, in 8.3 ppm nitric oxide in dry 92 percent nitrogen and 8 percent oxygen, and in nitrogen with 20 and 80 percent relative humidity. No neutralization was seen in dry nitrogen, dry oxygen, dry air, or 10 ppm nitric oxide in dry nitrogen. The diffusion coefficient of the neutral radium A species was found to be 0.079 square centimeters per second, regardless of the relative humidity of the nitrogen gas atmosphere. Lower values were observed for charged species.

Muskelung (Esox-masquinongy chiensis) fry were used in a 96 hour toxicity study with diquat and simazine. Although the death of sufficient control fish invalidated the test as a whole, some interesting observations were made. At the end of 48 hours 4 out of 10 fish had died in the control tank and 8 had died in the simazine tank while all 10 diquat-treated fish appeared healthy. Two model eco-systems with components from Chautauqua Lake, N.Y. were constructed in 20 gallon glass aquaria to trace the movement of 14C labeled diquat. After activity had reached near background levels in the water from the test tank, fish, plants, sediments and snails were counted in a liquid scintillation counter to discover the fate of diquat within the system. The concentration of diquat was found to be highest in sediments, followed by fish tissue, snail parts, with plants having the lowest measured concentration.