Acidity gradients in the kipda region

Acid precipitation leaves fingerprints upon marble surfaces. Preserved in weathering crusts on dated monuments, these fingerprints serve as guides to identify levels of acidity of a region. We collected scrapings from protected surfaces of tombstones made of Georgia marble whose dates of installation could be determined with reasonable certainty. These scrapings were allowed to equilibrate in 100 ml of deionized water, and the solutions were analyzed for, among other species, sulfates and nitrates. In Louisville, it was found that sulfate is present on tombstones that had been installed as late as 1985. However, to the east, 25 miles away, 1967 is the date of the latest monument with sulfate. An acidity map was produced showing time contours, in other words, the time needed to produce discernible quantities of sulfate. This map reveals that the effect of SO₂ on marble diminishes rapidly with increased distance away from the western Louisville industrial area. The use of marble monuments to monitor changes in the acid deposition patterns is suggested.