Predicting Calcium and Magnesium for Streams in the Great Smoky Mountains National Park

Tester, Robert

ABSTRACT: Calcium (Ca) and Magnesium (Mg) are vital to the overall health of a forest ecosystem. Their concentrations impact the soil and water chemistry, thereby having a direct effect on plant and animal life. There is currently some concern that acid rain in the Great Smoky Mountains National Park may be causing the Ca and Mg in the soil to be leached out and washed into the streams. If this is the case, obviously there could be vast consequences for the future of the Park ecosystem. A recent study by Harwell (2001), using data collected from 90 stream sites throughout the Park, analyzed many water quality characteristics for trends and influencing factors. At the time of the study accurate Ca and Mg data were not available for analysis. However, since May 2000 reliable Ca and Mg concentrations have been measured for those same 90 sites on a quarterly basis. The work of Harwell included the compilation of a database to describe the physical attributes of each watershed, or basin, where the stream samples are collected. This information was used to identify correlations between varioLls water quality measures and the basin characteristics and to formulate mathematical models to predict the values of the water quality constituents from the physical data. The purpose of this study was a parallel examination of the newly available Ca and Mg concentrations using the watershed database created by Harwell (2001). In light of the aforementioned importance of these two ions to the health of the overall Park ecosystem, discovering associations between them and the physical basin descriptions, and possibly even developing models that could soundly predict the former from the latter, would obviously prove invaluable. Granted," ... the presence of statistically significant correlations between basin characteristics and water quality constituents do not establish cause and effect relationships, [but] they can certainly provide insight into possible and reasonable causes" (Harwell 2001). The research and statistical procedures of Harwell were used extensively as a guide for this investigation, both to aide in understanding of the concepts and to maintain consistency within the information available regarding the water quality in the Park (2001).