Chemical alteration of limestone and marble samples exposed to acid rain and weathering in the eastern United States, 1984--1988
In a long-term program that began in 1984, limestone and marble briquettes have been exposed to both anthropogenic acid deposition and natural weathering of four field sites in the eastern United States. Similar tests began at an Ohio site in 1986. Effects of exposure on the briquettes and other materials at the sites are evaluated periodically by several federal agencies cooperating in the National Acid Precipitation Assessment Program (NAPAP). A primary contribution of Argonne National Laboratory to the NAPAP has been chemical analysis to determine changes in the samples caused by exposure to the environment. Wet chemical analysis was used to detect sulfates, nitrates, fluorides, chlorides, and a series of metal cations in sequential layers of stone removed from the briquettes after field exposure. Results from the first four years of the program indicate that rinsing by rain keeps skyward-facing stone relatively clean of reaction products, especially sulfate, the most abundant product. On groundward-facing samples, sulfate concentrations increased linearly with exposure time, and values were proportional to atmospheric SO{sub 2} concentrations at the site. Sulfate concentrations in groundward samples were much higher in limestone than in marble, because of the greater porosity of the limestone. A steep sulfate gradient was seen in both sample types from the surface to the interior. On skyward surfaces, material losses per rain event due to complete dissolution of accumulated sulfates were approximately equal to concentrations measured in runoff. Preexposed limestone samples had sulfate accumulations deep in their interiors, while fresh, unexposed limestone did not. No substantial changes in cation accumulations wee detected in either limestone or marble.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- DOI; Department of the Interior, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 6107458
- Report Number(s):
- ANL-89/34; ON: DE92004050
- Country of Publication:
- United States
- Language:
- English
Similar Records
Color measurements on marble and limestone briquettes exposed to outdoor environment in the Eastern United States. Volume I: Results of exposure 1984-1990
Chemical and mineralogical effects of acid deposition on Shelburne Marble and Salem Limestone test samples placed at four NAPAP weather-monitoring sites