Masters Theses

Date of Award

6-1981

Degree Type

Thesis

Degree Name

Master of Science

Major Professor

John P. Witherspoon

Committee Members

H. R. DeSelm, D. W. Johnson

Abstract

This research is part of a continuing series of studies conducted at Department of Energy (DOE) facilities to determine the environmental effects of hexavalent chromium from cooling tower drift on biological systems. Previous studies provided evidence of the transport of chromium in cooling tower drift to the landscape. Specifically, the purpose of this research was to address the potential for germination and growth effects in bush beans (Phaseolus vulgaris L. var Bush Blue Lake) from hexavelent chromium in Orocol TL (a proprietary chromated, zinc-phosphate compound added to DOE cooling water systems for corrosion inhibition) at low and high concentrations in the soil by adjusting soil pH and the percent of organic matter.

Germination effects were determined in bean plants grown in soils adjusted to differing pH ranges (4-4.5, 5-5.5, 6.5-7), levels of organic matter (1.8%, 3%, 5%) and Orocol TL amendments (control of 0 µg/g, 10 µg/g, 500 µg/g chromium). Growth responses (effects) were determined from bush bean plants cultured in the same soil treatment combinations as described for the germination study. Plants were harvested when the plant died or at the end of eight weeks and partitioned into leaves, stems and roots. Following weight determinations, the leaves, stems and roots were analyzed for total chromium content, and the results compared using analysis of variance and multiple comparison procedures.

Results of the germination experiment showed a significant (P < 0.05) effect from organic matter, soil chromium concentration and the interaction betv.'een organic natter and chromium concentration. At the higher concentration of chromium (500 µg/g), there was a lower percent germination. Plants grown in high organic matter (5%) had much higher percent germination even at the high level of chromium addition. The soil pH did not have a significant effect alone or in interaction with organic matter and chromium concentration.

Plants in the growth effects study that received 500 µg/g chromium wilted immediately and did not recover indicating that the hexavalent chromium exceeded the reducing and adsorbing capacity of the soil and roots. Chromium concentrations in the roots of plants of the 500 µg/g chromium treatment with a soil pH range of 4-4.5 were significantly (P < 0.05) lower than at the other pH levels. Plants of the 0 and 10 µg/g treatment groups were harvested at the end of eight weeks. There was a significantly (P < 0.05) greater amount of chromium in the leaves, stems and roots of the plants receiving the 10 µg/g chromium addition as compared to the controls. Dry weights of roots of plants grown in 3% organic matter were significantly (P < 0.05) less than the 5% treatment and the dry weights for roots grown in the soil pH range of 6.5-7 v/ere significantly (P < 0.05) lower than at pH 5-5.5. Leaf dry weight was significantly greater (P < 0.05) in the order of soil pH 5-5.5 > pH 6.5-7 > pH 4-4.5 and was significantly less (P < 0.05) in soils amended to 10 µg/g chromfum as compared with controls. There were no significant dry weight differences in the stems.

High levels (500 µg/g) of hexavalent chromium in soil (as Orocol Tl.) affected germination and growth, while a high level of organic matter significantly reduced chromium toxicity on germination. At lower chromium concentrations there was significant uptake by all plant parts, with a corresponding reduction in biomass of leaves. Consequently, adjustments of soil pH from 4.0 to 7.0 appear to have no significant effect on chromium uptake in plants. Increasing the organic matter level to 5%, while decreasing the toxicity of high chromium levels to germinating seed, did not affect chromium uptake.

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