Microbial contamination of groundwater could induce waterborne diseases such as hepatitis A, viral gastroenteritis, cholera, typhoid fever and giardiasis. Microbes being living organism, their transport in the groundwater is different than abiotic materials (Ginn et al., 2002). Physical processes such as advection, dispersion, straining, filtration, electrostatic and chemical process are responsible for microbial transport in groundwater (Ginn et al., 2002).
Microbial transport has been found to be controlled by hydrogeological heterogeneity of subsurface sediments (AGU, 2001). Various factors such as adhesion processes, filtration effects, physiological state of the cells, porous medium characteristics, water flow rates and intrinsic mobility of the cells determine the microbial transport activities (Newby et al., 2000).
Microbial transport is affected by the availability of pore space between soil particles. Size of the microbes should be smaller than micro pores for the filtration to occur. Nutrient availability affects the size of the microbes influencing microbial movement (Newby et al., 2000). Properties of cell surface and microbial adhesion influences microbial transport in the soil particles. pH value of the porous medium matrix solution has impacts on microbial transport (Newby et al., 2000). Viral adsorption and transport has been found to be affected by pH (Newby et al., 2000).
Ionic strength or the concentration of cations and anions in solution affects microbial transport. Decrease in ionic strength of the solution facilitates increased bacterial transport (Newby et al., 2000). Availability of cellular appendages such as pili, flagella, or fimbria and hydrological factors such as soil texture, soil structure, porosity, water content, and water movement affects microbial transport (Newby et al., 2000). Pore water velocity and bacterial attachment to grain surface and detachment from grain surface controls the rate and extent of bacterial movement in groundwater (AGU, 2001).
American Geophysical Union (2001) Breakthroughs in Field Scale Bacterial Transport, Eos, Transaction, Vol 82(38), pp. 417, 423-425.
Ginn, T.R., Wood, B. D., Nelson, R. E., Scheibe, T.D., Murphy, E.M. and Clement, T.P. (2002) Processes in Microbial Transport in the Natural Subsurface, Advances in Water Resources, Vol 25, pp 1017-1042.
Newby, D.T., Pepper, I.L. and Maier, R.M. (2000) Microbial Transport [Online] Available at http://www.elesevier.com [16 August 2014]