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Dissertation
The significance of streambed sediments as a reservoir of Cryptosporidium oocysts
Doctor of Philosophy (Ph.D.), Drexel University
Apr 2004
DOI:
https://doi.org/10.17918/etd-290
Abstract
The identification of the sources and mechanisms for the fate and transport of Cryptosporidium is important to its control by water suppliers and public health officials. This study examines the role that sediments have in concentrating and resuspending Cryptosporidium oocysts in the environment and its potential impact on water column concentrations. To investigate these aspects of sediment, a new analytical method was successfully developed in this study to isolate and recover Cryptosporidium oocysts from sediment matrices. The new method observed recoveries within the requirements for all ranges established in USEPA Method 1623. A field study was also performed to characterize the presence and concentrations of Cryptosporidium oocysts in local streambed sediments. Cryptosporidium oocysts were detected in the sediments at a frequency similar to that observed in the water column (33%). Comparing the mean concentrations in the sediment and in the water column, concentrations of Giardia and Cryptosporidium in the sediment were 80 and 147 times greater than in the water column respectively. The equivalent median concentration of Cryptosporidium in sediment was statistically greater than that in the water column during the study period. Streambed sediment resuspension was estimated to comprise from 4% to 27% of the total Cryptosporidium flux for the Wissahickon Creek depending upon the depth of sediment resuspended and the range of concentrations in the sediment and water column. It was also estimated that resuspension of the top 1 to inches of sediment could increase concentrations in a standing water body (lake or reservoir) by a factor of ten. Based on these findings, sediment has the potential to play a significant role in any watershed as a significant source and sink of Cryptosporidium oocysts and therefore must be factored into most, if not all, watershed management and public health strategies. The most effective approach may include employing combined strategies focused on reduction or treatment of elevated levels of Cryptosporidium from constant discharge sources, overland sources, or sediment loading and bed load transport in a manner that is complimentary to existing programs designed to address other contaminants and balanced against cost effectiveness measures.
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Details
- Title
- The significance of streambed sediments as a reservoir of Cryptosporidium oocysts
- Creators
- Christopher Scott Crockett - DU
- Contributors
- Charles Nathan Haas (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems (1997-2026); Drexel University
- Other Identifier
- 290; 991014632165304721