Total Coliform Survival Characteristics in Frozen Soils

Survival characteristics of total coliform bacteria in soil samples, with different moisture contents (24–49%) and at different temperatures (from −28 to 20°C), were studied. The study showed that a significant fraction of coliform bacteria survive for more than six months in soil at subfreezing temperatures. Survival of total coliform bacteria at subfreezing temperatures decreased with an increase in moisture content and an increase in temperature. For 24% moisture, approximately 66% of the coliforms survived at −28°C after 170 days, whereas less than 0.1% survived at room temperature. First-order die-off rate constants varied between 0.041/day at room temperature and 0.002/day from −15 to −28°C (for 24% moisture). The impact of temperature on the die-off rate constant was described by the Arrhenius equation. The high survival at subfreezing temperatures indicates that fecal bacteria at honeybucket dumpsites may survive throughout the Alaskan winter which may lead to the contamination of water sources during spring thaw.