Temporal variation and persistence of bacteria in streams

Area of Science:

• Environmental microbiology
• Water quality assessment
• Statistical hydrology

Background:

• Effective management of impaired streams necessitates a thorough understanding of bacterial fate and transport within watersheds.
• Coliform bacteria levels are a key indicator of water quality and potential health risks.

Purpose of the Study:

• To analyze temporal variations in total coliform concentrations in the Little River, East Tennessee.
• To determine the presence and duration of short-term and long-term persistence in total coliform data.
• To evaluate the utility of novel statistical time series analyses for bacterial dynamics.

Main Methods:

• Daily total coliform data from October 2000 to December 2005 were analyzed using time series techniques.
• Time domain analysis employed an autoregressive moving average (ARMA) approach.
• Frequency domain analysis utilized spectral analysis for robust evaluation.

Main Results:

• Total coliform concentrations exhibited expected seasonal patterns, higher in summer and lower in winter.
• Significant short-term persistence (approx. 4 weeks) and long-term persistence (approx. 1 year) were identified.
• Both runoff and baseflow were found to contribute to bacterial persistence in the watershed.

Conclusions:

• Statistical time series analysis is a valuable tool for understanding bacterial dynamics and persistence in watersheds.
• The identified persistence patterns of coliform bacteria have implications for water resource management and regulatory strategies.
• Hydrological factors, including runoff and baseflow, play a critical role in sustaining bacterial presence in river systems.