ABSTRACT
ABSTRACT: Anthropogenic solutes and microorganisms detected at depth-specific intervals within actively pumped, urban sandstone aquifers in the UK, provide coarse estimates of aquifer penetration rates (sets of vertical groundwater velocities). Stable isotope tracers (15N/14N, 34S/32S) indicate that solutes derive primarily from anthropogenic sources whereas detected bacteria (Escherichia coli, faecal streptococci) and viruses (coliphage, enterovirus) reflect a faecal origin. Low concentrations of these microorganisms are detected sporadically though often proximate to aquifer heterogeneities whereas concentrations of anthropogenic solutes gradually decrease with increasing depth from the surface. Observed contaminants trace different sets of vertical groundwater velocities as faecally derived microorganisms indicate aquifer penetration rates (md1) that are orders of magnitude more rapid than aquifer penetration rates suggested by anthropogenic solutes (ma1). Further research is required to test conceptual models of microbial transport and to resolve further the distribution of groundwater velocities using a range of environmental tracers.
