Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Borazjani, Hamid

Committee Member

Prewitt, M. Lynn

Committee Member

Nicholas, Darrel D.

Committee Member

Kitchens, Shane

Committee Member

Diehl, Susan V.

Date of Degree

1-1-2011

Document Type

Dissertation - Open Access

Abstract

This study examined the effect of in-situ biosparging on pentachlorophenol (PCP) degradation and bacterial communities in PCP contaminated groundwater. Bacteria were identified by sequencing the 16s rDNA fragment from DNA extracted from groundwater cultures and comparing those sequences to a database using a basic local alignment search tool, BLAST. The PCP-degraders Burkholderia cepacia and Flavobacterium (Sphingobium) chlorophenolicum were identified in multiple wells, as were the 4-chlorophenol degrader Herbaspirillum sp., and the common soil bacteria Pseudomonas sp., Aquaspirillum sp., and Rhodocista sp., among others. Numerous bacterial samples also appeared in the results as “uncultured”. Bacterial community changes were observed using terminal restriction fragment length polymorphism (TRFLP) analysis to identify operational taxonomic units of bacteria at various locations inside and outside the biosparging zone of treatment over time. Diversity measures including species richness, Simpson’s and Shannon’s indices, and species evenness were calculated from operational taxonomic unit results for each well at each sampling point in order to better understand changes in the bacterial community. Species richness tended to be higher at wells further away from the biosparging line, while diversity and evenness varied throughout the area. Correlations between PCP concentration, operational taxonomic units, and distance from biosparging wells were determined by Pearson’s product-moment correlation and Spearman’s rank correlation. Positive correlations were found between distance from biosparging wells and PCP concentration, species richness and distance, and to a smaller degree, diversity and distance. Biosparging remediation has a significant impact on the types of PCP-degrading bacteria within the groundwater matrix, and installations of this type of treatment should be applied to maximize the use of the native bacteria to assist in degradation of the contaminant.

URI

https://hdl.handle.net/11668/17839

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