Environmental fate and biodegradability of benzene derivatives as studied in a model aquatic ecosystem.

Abstract

A model aquatic ecosystem is devised for studying relatively volatile organic compounds and simulating direct discharge of chemical wastes into aquatic ecosystems. Six simple benzene derivatives (aniline, anisole, benzoic acid, chlorobenzene, nitrobenzene, and phthalic anhydride) and other important specialty chemicals: hexachlorobenzene, pentachlorophenol, 2,6-diethylaniline, and 3,5,6-trichloro-2-pyridinol were also chosen for study of environmental behavior and fate in the model aquatic ecosystem. Quantitative relationships of the intrinsic molecular properties of the environmental micropollutants with biological responses are established, e.g., water solubility, partition coefficient, pi constant, sigma constant, ecological magnification, biodegradability index, and comparative detoxication mechanisms, respectively. Water solubility, pi constant, and sigma constant are the most significant factors and control the biological responses of the food chain members. Water solubility and pi constant control the degree of bioaccumulation, and sigma constant limits the metabolism of the xenobiotics via microsomal detoxication enzymes. These highly significant correlations should be useful for predicting environmental fate of organic chemicals.

Some Physical Factors in Toxicological Assessment Tests

“…Conversely, the partition coefficient is larger. It would be expected, therefore, that these compounds might more readily partition through lipophilic membranes and thus gain more ready access to the interior of the cell and to the target site (13,14). Figure I is a plot of the log of the water solubility versus the logarithm of the partition coefficient.…”

“…As a further assessment of the validity of the relation between partition coefficient and accumulation, these two factors were compared (13,14). Table 4 presents limited number of data of partition coefficient and bioaccumulation.…”

Environmental fate of five radio-labeled coal conversion by-products evaluated in a laboratory model ecosystem

“…Quenching was corrected by channels ratio method (20). The radiosasay technology, separation, and identification were carried out exactly as previously described (10,21).…”

“…Water solubility was determined by shaking saturated solutions of the radiolabeled compounds for 24 hr at 25°C. After filtration and centrifugation the radioactivity was determined in the water (21). The values as determined for the five compounds studied are presented in Table 1.…”

“…Biologically, the degradative pathways of fluorene degradative products in the extractable 3H from the various organisms are compared in Table 5. It is apparent that the fish has a better capacity to detoxify fluorene through microsomal oxidations than the organisms of lower phylogenetic position (21).…”