Dr. Andrew Rogerson, formally of the Oceanographic Center of Nova Southeastern University, in Florida, headed an Environmental Protection Agency study to determine the levels of fecal-derived bacteria in Florida beach sand.
Early results showed wet sand and dry sand had significantly more fecal bacteria than near-shore seawater.
The study, published in the Journal of Environmental Quality, found all the feces-derived bacteria -- an indicator of sewage contamination -- were capable of enhanced survival in sand and, more importantly, were capable of growth in the sand leading to much higher numbers.
Conversely, in seawater the bacteria steadily decreased in number over time. Results also showed a rapid drop off in bacterial numbers in bathing water sampled close to the sand compared with five, 10 or 20 yards from shore. This indicates the shoreline water is affected by bacterial run-off from the sand, Rogerson said.