Persistence of Chlorinated Dioxins and Furans in the Soil Environment

The persistence of di- to octachloro dioxins and furans has been investigated in various soil environments. Over a 15-month period, measurable degradation - i.e., that leading to loss greater than the precision level of the analytical methodology - was found to occur only in the case of di- and trichloro congeners. The degradation of tetra through octachloro congeners was minimal. In the absence of a carrier co-pollutant, the mobility rates of chlorinated dioxins and furans are not significantly affected by the presence of co-pollutants such as pentachlorophenol and creosote components which are commonly present at wood treatment sites

On Translocation of 2,3,7,8-tetrachlorodibenzo-p-dioxin: Time Dependent Analysis at the Times Beach Experimental Site

The rate of migration and loss of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in contaminated soil has been studied under natural conditions in experimental plots at the Dioxin Research Facility, Times Beach, Missouri. The TCDD concentration profiles of sample cores taken at Times Beach in 1988 are virtually the same as those in cores taken in 1984. The data confirm our earlier work with soil columns exposed to simulated environmental conditions in the laboratory, and lead us to conclude that little movement and essentially no loss of TCDD has occurred in the experimental plots in the four years since the Dioxin Research Facility was established

Role of Dispersing Medium on the Disposition of 2,3,7,8-TCDD in Soil

The contamination with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds of many sites in Missouri is without doubt the single most publicized environmental issue in the state. The detection of TCDD residues in fish and sediment samples downstream from contaminated sites in Missouri indicates migration of the compound from these sites, necessitating a closer examination of migration modes of TCDD from soil into the aquatic environment. The role of the dispersing medium on the disposition of TCDD in soil is being studied in our laboratory. The objective of these studies is to monitor the effect of carrier medium on the migration and loss of TCDD in selected soil types representative of contaminated soil sites

Application of a Two-dimensional Reaction Chromatography System for Confirmatory Analysis of Chlordane Constituents in Environmental Samples

Confirmation of Chlordane components in fish tissue and sediment samples was performed with a two-dimensional reaction chromatographic system. A 30 cm length of nickel tubing was employed as an in-line hydrodehalogenation reactor

Role of Entrainers in Supercritical Fluid Extraction of Chlorinated Aromatics from Soils

The application of supercritical fluid technology holds considerable potential for removing toxicants from soil. The use of carbon dioxide at temperatures and pressures above its critical point was evaluated for removal of such contaminants as chlorinated pesticides, polychlorinated biphenyls and chlorinated phenols. Experiments were carried out to optimize the extraction parameters and define the role of entrainers under varied matrix conditions

The effect of dose rate on genetic damage from fast electrons in drosophila sperm /

"Technical Objective AW-6.""Biology and Medicine.""NM 62-03-60, FCDA.""31 March 1958."Includes bibliographical references (page 13).Mode of access: Internet

Field and Laboratory Studies on Sources and Persistence of Chlordane Contamination in the Missouri Aquatic Environment

Field and laboratory studies were conducted to investigate the persistence of chlordane in the aquatic and terrestrial environment. The laboratory data show that the transformation and loss of the chlordane constituents is dependent on soil characteristics. The overall rate of loss is also dependent on the depth of application, being significantly lower at greater depths. The field data show a strong correlation between urban development and residue concentration levels

Studies of Parameters Affecting Translocation of Tetrachlorodibenzo-p-dioxin in Soil

A study designed specifically to examine the partition behavior of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans under a variety of environmental conditions is currently underway. The present report deals with experiments conducted to monitor the distribution coefficient of TCDD in waste oil and soil, to determine the effects of organic loadings on partitioning of TCDD in soil-water and oil/water methanol systems, and to monitor the effects of surfactants on partitioning of TCDD

Evaluation of Carbon for Removal and Destruction of Polychlorinated Biphenyls (PCBs) from Transformer Mineral Oils

Adsorptive removal of PCBs by carbon followed by destruction through an oxidative carbon regeneration process were evaluated. The combined processes performed well for PCBs with lower chlorine content. Adsorption efficiencies of ≥ 95% were achieved for lower chlorinated PCB formulations such as Aroclor 1240, adsorption efficiencies for higher chlorinated PCBs were considerably lower. The regeneration process was highly effective and ≥ 99.7% of the adsorbed PCBs were mineralized or converted to unrecoverable forms