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Microbial partitioning to settleable particles in stormwater
Gregory W Characklis1, Mackenzie J Dilts, Otto D Simmons
1Department of Environmental Sciences and Engineering, School of Public Health, Rosenau Hall - CB7431, University of North Carolina, Chapel Hill, NC 27599-7431, USA. charack@email.unc.edu
Water Research
|May 19, 2005
Summary
Microbes in urban streams attach to particles, influencing water quality. This attachment, especially during storms, affects microbial transport and removal, crucial for water quality modeling.
Area of Science:
- Environmental microbiology
- Water quality science
- Ecotoxicology
Background:
- Microbial association with particles impacts water transport and sedimentation.
- Understanding this partitioning is vital for accurate surface water quality models.
Purpose of the Study:
- To investigate the partitioning of microbial indicator organisms with settleable particles in urban streams.
- To compare microbial-particle association under dry and storm weather conditions.
Main Methods:
- Utilized a centrifugation technique to quantify the fraction of microbes attached to settleable particles.
- Calibrated the technique using standard particle suspensions (glass, latex).
- Analyzed partitioning for bacterial, protozoan, and viral indicators in three urban streams.
Main Results:
- Microbial partitioning varied by organism type and weather conditions.
- Bacterial indicators (fecal coliforms, E. coli, enterococci) showed 20-35% particle association in dry weather and 30-55% in storms.
- Clostridium perfringens spores had higher association (50-70% in storms), while total coliphage showed variable results (20-60% in storms).
Conclusions:
- Microbial partitioning to settleable particles is significant and condition-dependent.
- Current water quality models often overestimate free-living microbes, neglecting particle association.
- These findings improve microbial transport and removal estimations in surface water models.