Investigation of the contribution of aquatic humus to the transport of DDT in the environment

Abstract

1982 ABSTRACTThe fate and transport of insoluble, hydrophobic organic pollutants in the aquatic environment constitutes a prominent area of concern. It is thought that pollutants of this nature may exist in association with organic carbon, which is predominantly aquatic humus. This type of association could significantly affect the kinetics of such transformation processes as volatilization or chemical and biological degradation of the pollutant. While dissolved organic matter (DOM) comprises the bulk of organic carbon (or aquatic humus) in natural waters, the interact·io',\ between naturally occurring DOM and insoluble organic pollutants has not been quantified.The work presented in thi s di ssertation is an effort to quantify the, effect of dissolved organic matter on the solubility in water and, hence, the transport of hydrophobic organic compounds (specifically, DDT) in the environment.Saturated aqueous solutions of DDT were generated by a method that is different from those used by other workers. Within a closed system, an excess of sol id DDT was allowed to vaporize and enter an aqueous solution through the gas phase. The concentraction of DDT in solution increased with time, 1 eve 1 i ng off when equil i bri urn and a saturated solution was established.The solubility of p,p'-DDT in distilled water was determined to be 1.87 ± .01 ppb. The solubility of the o,p'-DDT isomer in distilled water was determined to be 4.88 ± .03 ppb. The concentrations of p,pl-3 DDT and o,pl-DDT in distilled water solutions containing dissolved organic matter were definitely higher than the aqueous solubilities of these compounds. A minimum value for the DDT/DOM partition coefficient (Kp) in water was determined. This partition coefficient, when normalized to organic carbon, is referred to as Koc (K oc = Kp/fraction organic carbon). A minimum log Koc for both p,pl-DDT and o,pl-DDT was determined to be 4.7 ± .2 log units. Under environmental conditions, this partition coefficient indicates that the majority of DDT present in aqueous systems will be associated with dissolved organic matter.

The copper complexation properties of dissolved organic matter from the Williamson River, Oregon

“…The second problem was the characterization of the three main DaM fractions in the Williamson River. While humic substances can be readily estimated via their color at 420 nm (Blunk, 1982), analysis for the carbohydrate and proteinaceous fractions is non-routine. The focus of this research was on the proteinaceous fraction.…”

“…Assay for Humic Carbon. A sample of humic substances had been isolated from the Williamson River by Blunk (1982), and its carbon content analyzed. Various known weights were dissolved in purified water, buffered to pH 10, and the absorbances measured at 420 nm.…”