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A comprehensive, multilevel approach is used for characterizing element speciation and leaching behavior in electrostatic precipitator ash from solid waste incinerators. The results showed that the use of neutron activation analysis, x-ray powder diffraction, scanning electron microscopy, x-ray microanalysis, Auger electron spectroscopy, secondary ion mass spectrometry and x-ray photoelectron spectroscopy was effective although it was expensive and time-consuming.

Various methods for characterizing reactive pools of iron found in soils and aquifer sediments were applied to samples gathered from a leachate plume at a landfill in Vejen, Denmark. Results revealed that reduced iron oxides on the sediment act as important buffers against the entering leachate in polluted aquifers. However, the presence of reduced precipitates may result in a growth in aquifer oxygen requirements, which will certainly influence bioremediation.

Introduction The fate of organic chemicals applied at or near the surface, relative to the contamination of underlying ground-water resources, is of great concern. Several elaborate studies have been undertaken [...]

The movement of atrazine, simazine, cyanazine, and metolachlor was studied for two years under conventional tillage and no-tillage corn. Ground water and soil samples were analyzed for the herbicides. Atrazine and simazine were detected in the ground water more frequently than metolachlor or cyanazine. In 1987, the herbicides were leached to the ground water nine days after they were applied when 31.5 mm of rainfall occurred. At the 3.0 m depth atrazine concentrations ranged from 0 to 17 micrograms/L. There was no significant difference in herbicide movement between conventional tillage and no tillage. The frequency of the herbicides detected in the ground water was directly related to the soil half-life of the herbicide. Concentrations of the herbicides detected in the ground water were not related to the water solubility of the herbicide. The research demonstrates pesticides may move to shallow ground water by macropore flow in the sandy soils of the Mid Atlantic states if sufficient rainfall occurs shortly after they are applied.

An investigation was conducted to determine the types of chemical reactions that occur when municipal solid waste (MSW) ash comes into contact with water in batch reactors. The result showed that MSW ash and water exhibit four basic types of solution behavior with time: equilibrium, kinetic, availability and a combination of availability and kinetic behaviors. The batch reactor experiments man be used to understand some of the geochemical process involved in the alteration of ash.

The environmental impact of aluminim from red mud was analyzed by studying its solubility in chemical and biological leaching agents. Chemical leaching, which used sulfuric, citric and oxalic acids, showed high solubilization for aluminum when mixtures of organic and inorganic acids were used. Likewise, aluminum showed high solubility in the presence of thiobacilli and fungi. The high solubility of aluminum in the two processes indicate that certain acids, such as sulfuric acid and acids from biological sources, are effective leaching agents.

The anlytical method used for evaluating the performance of landfill caps allows for a constant head boundary to be assumed around the perimeter of the landfill and solving the two-dimensional problem by utilizing the linearized form of the Boussinesq equation. It is assumed that the percolation rate from rainfall or other sources is stable, and this is the only source for leachate generation and mound development. Since the leachate mound is sensitive to variations in the percolation rate, the effectiveness of different cap conditions can be estimated by controlling the leachate level within the leachate mound after cap installation.

A simulation technique was applied to include the multivariate character of leachate quality, as revealed by the data on 13 median leachate qualities at 56 landfills, to estimate false negative error rates for statistical tests of ground-water quality that ignore correlations among water quality parameters. When applied to a control chart, the results of intrawell statistical tests of aquifer contamination show that the false positive/negative errors of statistical tests can be decreased when more parameters and a higher confidence level are used.

Nitrate leaching was measured under no-till and conventional tillage irrigated corn on a sandy loam soil. Ground water was sampled monthly for two years. Soil samples were taken three or four times a year to a depth of 150 cm. Nitrate concentrations were above 10 mg/L for most sampling dates. Most of the nitrogen was leached during the fall and winter months. The mass of nitrate leached from the no-till plots ranged 55.0 to 78.8 kg/ha/yr. The mass of nitrate leached from the conventional plots ranged from 57.1 to 94.0 kg/ha/yr. The mass of nitrate leached was slightly higher under conventional tillage than no-till. Nitrate leaching would be difficult to control, because most of the nitrogen is leached during the late fall and winter. Proper nitrogen applications for realistic yield goals is probably the best method for controlling nitrate leaching.

A method for the low-level sampling and analysis of sulfur speciation from reductive dissolution reactions is discussed. Strict sample handling procedured were adopted to minimize volatilization losses. Ion chromatography was used as the sample-specific chemical analysis method in the leaching experiments. The applicability of the method for other aqueous samples with metal catalysts was established.

The sulfur and ferrous-iron oxidizing bacterial populations in mine and dump biotopes were investigated. Pure cultures of Lepstospirrillum ferroxidans, Thiobacillus ferooxidans and Thiobacillus thiooxidans were isolated and studies on morphological, physiological and genetic characterization were done. Studies of leaching capacities of the three species were also conducted.

Backscatter electron microscopy of subaerial rock varnish reveals porous textures that are sites of cation leaching with lowered ([K.sup.+] + [Ca.sup.2+)/[Ti.sup.4+] ratios and concentrations of manganese and iron. Laboratory studies show that rates of potassium and calcium leaching increase with temperature, time, and surface area, and decrease when varnish interdigitates with coatings of amorphous silica. Only varnishes with continous layering should be used in paleoenvironmental research and paleomagnetic studies, not textures indicative of postdepositional modifications.

A reassessment of Polynov's ion mobility series in rocks reveals that his use of the elemental composition of igneous rock in his study caused Polynov to make significant overestimates of the amount of Na relative to Ca in rocks that leach into rivers. The relative mobility of Na is 18.0 which is much more than calcium (8.1), Mg (5.4), or K (3.5). Thus Na deserves to be placed in a distinct mobility phase second in relative mobility to Cl and SO4.

The leaching of reducing sugars sugars in raw and previously frozen carrot cortex tissue as a function of temperature was studied. Results showed that at low temperatures small losses in reducing sugars occurred in raw carrots and the diffusion model describing Fick's second law can only be applied at higher temperatures. The Fickian behavior can be applied in the entire range of temperatures for previously frozen carrots. Diffusion of reducing sugars depended on temperature as described by an Arrhenius type equation for raw and frozen carrots.