The effects of temperature and motility on the advective transport of a deep subsurface bacteria through saturated sediment

Abstract

Replicate column experiments were done to quantify the effects of temperature and bacterial motility on advective transport through repacked, but otherwise unaltered, natural aquifer sediment. Greater microsphere removal observed at the higher temperature agreed with the physical-chemical model, but bacteria removal at 18°C was only half that at 4°C. The sticking efficiency for non-motile A0500 (4°C) was over three times that of the motile A0500 (18°C), 0.073 versus 0.022 respectively. Motile A0500 bacteria traveled twice as far as non-motile A0500 bacteria before becoming attached. Once attached, non-motile colloids detached on the time scale of 9 to 17 days. The time scale for detachment of motile A0500 bacteria was shorter, 4 to 5 days. Results indicate that bacterial attachment was reversible and detachment was enhanced by bacterial motility. The kinetic energy of bacterial motility changed the attachment-detachment kinetics in favor of the detached state.