Geology topics

D. Swineford

Publications and source records attributed to D. Swineford.

3 recordsLinked to original sources

USGS1987

Changes in litter near an aluminum reduction plant

Litter was collected from eight sites at distances as far as 33 km from an Al reduction plant in western Tennessee. As a result of an accumulation of fine litter (<4.75 mm) the weight of the litter per unit area was abnormally high at the two sites within 2 km of the plant. Compared to litter collected far from the plant, it had a lower fiber content, was more sapric, and was less acid. Fluoride emissions from the plant were suggested as the probable cause of litter changes. Concentrations of water-extractable and acid-extractable F − in the litter, the 0- to 5-cm soil layer, and the 5- to 15-cm soil layer were strongly correlated with distance from the plant. Total acid-extractable F − in the litter and upper 15 cm of soil was about 41 times as much at the closest site (700 mg/kg) as at the most distant sites (12 and 16 mg/kg). In a bioassay of litter from our study sites, woodlice ( Porcellio scaber Latr.) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid-extractable F − . However, when F − was added as NaF to litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg. The decrease in the rate of decomposition of the litter might eventually induce a deficiency of soil macronutrients, but none was detected.

Journal of Environmental Quality↗

USGS1980

Toxic effects of endrin and toxaphene on the southern leopard frog Rana sphenocephala

Eggs, larvae and sub-adults of the southern leopard frog Rana sphenocephala were exposed to endrin and toxaphene. Exposure was in water by a continuous-flow technique, following standards that have been used successfully in the study of fish and invertebrates. R. sphenocephala is more sensitive to both pesticides than are higher vertebrates but is slightly less sensitive than fish. Eggs seem to be resistant to the effects of both pesticides and are probably poor indicators of environmental hazard. The toxic level of endrin is about equal in larvae and transformed frogs (LC 50 , 0·005-0·015 ppm). Toxaphene is less toxic to sub-adults (LC 50 , 0·37-0·790 ppm) than to larvae (LC 50 , 0·032-0·054 ppm). Delayed mortality, behavioural aberrations and effects on growth have been seen in toxaphene-dosed larvae observed over 30-day periods. Behavioural effects are more severe than those reported in other groups of animals. Effects on growth resulting from a 96-h exposure begin in the 0·013-0·018 ppm range. The maximum accumulation of residues observed for each chemical represented bioconcentration factors of about 100. Endrin residues are apparently lost more readily than toxaphene residues; relative depuration rates correlate well with the time course of toxic action in each chemical. Although less sensitive to these pesticides than fish, amphibians may not be protected in their natural habitats. Future studies of the effects of toxicants on amphibians should employ larvae if only one stage can be tested, should expose subjects for at least 96 h and should continue observations for a total of at least 30 days.

Maryland↗

USGS1979

Uptake of methoxychlor from food and water by the American toad (Bufo americanus)

Various studies (Mulla et al. 1963; Ferguson and Gilbert 1967; Cooke 1973) have examined the effects of pesticides on anuran amphibians, but the routes of contaminant uptake by transformed amphibians have not been evaluated. The need of frogs and toads to imbibe water from natural surface water would seem to make them vulnerable to uptake from this source. Fish are known to accumulate pesticides from both food and water (Jarvinen et al. 1977). Toads are more terrestrial and tend to lose water less readily than most other amphibians (Thorson and Svihla 1943); hence they should he a conservative estimator of the potential for uptake of pesticides from water. Methoxychlor is an analogue of DDT and has been widely used to replace it. It is a good model of many pesticides in current use in its low persistence in animal tissues (Gardner and Bailey 1975), and its long half life in water (Wolfe et al. 1977). It is also suitable for study because of its relatively low toxicity to amphibians (Kaplan and Overpeck 1964) and its easily detected residues. In the present study we measured the accumulation of methoxychlor from food and water in a preliminary evaluation of the two routes of exposure.

Bulletin of Environmental Contamination and Toxico↗