Masters Theses

Date of Award

3-1981

Degree Type

Thesis

Degree Name

Master of Science

Major

Microbiology

Major Professor

Gary S. Sayler

Committee Members

W. O. Smith, T. C. Montie

Abstract

Microbial mediated organic matter mineralization was examined in freshwater sediments under various environmental conditions ranging from natural reservoir sediment, xenobiotically stressed microcosm sediments and stream sediments recovery from coking effluent contamination. Organic matter mineralization activity was estimated by trapping respired 14C02 in an alkaline solution and quantified using liquid scintillation techniques. The substrates used were uniformly (14C) glucose, protein, starch and oleic acid. A single substrate concentration was used to obtain mineralization rates for relative comparisons.

Organic matter mineralization in natural sediments indicated that glucose and protein mineralization rates were inversely related with respect to temporal trends. Glucose mineralization rates were lowest during winter periods (40.5 ng respired h-1 g-1 dry wt) and highest during summer periods (48.4 ng respired h-1 g-1 dry wt), while protein mineralization rates were highest in the winter (5.7 ng respired h-1 g-1 dry wt) and lowest in the summer (3.6 ng respired h-1 g-1 dry wt). The seasonal differences were statistically significant for both glucose and protein mineralization. Starch mineralization rates had no statistically significant differences whereas oleic acid mineralization did, although a temporal trend was not evident. The method used to collect sediment samples influenced glucose mineralization rates.

The impact of PCB (Aroclor 1254) and phenanthrene on the rate of glucose mineralization was variable. PCB and phenanthrene concentrations of 10 and ICQ ppm and exposure times up to 90 days had no significant effect on the rate of glucose mineralization; however, exposure to phenanthrene (1 ppm) for 184 days had a significant stimulatory effect. Also, addition of PCB (250 and 500 mg) and phenanthrene (82 and 166 mg) to microcosms (37 days exposure time) had significant stimulatory effects on the rate of mineralization. Similar stimulatory effects on mineralization were also observed with coal-derived oils and diesel fuel treatments. The organic matter mineralization response of Saucon Creek to effluent diversion suggests that Saucon Creek was in a recovery period and the resiliency of the microbial community was observed.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS