GIS Use at St. Lawrence University
Some examples of current classes and recent student projects utilizing GIS:
An Investigation of Stream Chemistry Variability in Watersheds of Central St. Lawrence County, New York
By John Murphy, Dr. Jeff Chiarenzelli, Dr. Matt Skeels, & Carol Cady
Abstract:
Sixty water samples from five small watersheds (<250 km2) in northern New York, were analyzed for major and trace element chemistry, major anions, acid-neutralizing capacity (ANC), and various physicochemical parameters in an effort to understand the geochemical variability in the headwaters of the Oswegatchie, Grasse, and Raquette Rivers. The data suggests that lithology, elevation, land use, wetlands/lakes, and mine drainage are locally important factors in small streams. Major lithological and land-use changes occur across the Carthage-Colton Mylonite Zone which separates Meso-Proterozoic rocks of the NW Adirondack Lowlands from the Adirondack Highlands to the SE. The Lowlands are underlain primarily by metasedimentary rocks, including abundant marble and calc-silicate gneisses, whereas the Highlands contain mostly acidic metaigneous rocks with minimal buffering capacity. ANC values were experimentally determined for all rocks types in each drainage basin, including quaternary deposits, and ranged from 82 mg CaCO3/kg (Grenville marble) to 20.5 mg CaCO3/kg (Cambrian Potsdam sandstone). The ANC value of each rock type was normalized to its areal extent and the relative acid neutralization capacity of each subbasin was determined. Average values for the five drainage basins ranged from 24.4 to 38.1 from the Highlands to the Lowlands and were strongly influenced by the presence of marble. The largely forested (74-84%), sparsely populated, southern portion of the county is highly impacted by acid precipitation but even within this area the extent of acidification and Al concentrations are variable and primarily a function of bedrock lithology and elevation. The effects of drainage from tailings of an abandoned iron mine strongly influence the geochemistry of several tributaries, particularly concentrations of TDS, Fe, Mn, and REEs. Stream waters draining the Adirondack Lowlands, with considerable agricultural land-use activities (19-37%), have higher pH, ANC, TDS values, and are dominated by Ca and Mg, and other soluble elements.
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An Investigation of the Inorganic Geochemistry and Drinking Water Quality of Groundwater in St. Lawrence County, New York
By Michael O’Connor, Dr. Jeff Chiarenzelli, & Carol Cady
A multi-element study of groundwater quality in St. Lawrence County, a large (7306 km2) and sparsely populated (112,000), rural, largely forested county in northern New York, has been carried out. Bedrock varies from south to north across the county from Precambrian crystalline granulite facies gneisses of the Adirondack Highlands, to mid-upper amphibolites facies metasedimentary rocks and intrusive granitoids of the Adirondack Lowlands, to flat-lying Paleozoic sandstones and dolostones of the St. Lawrence River Valley. A total of 99 groundwater samples were collected from private well owners between July and August 2008. The samples have been analyzed for seventy-two inorganic metal and trace elements by Inductively Coupled Plasma – Mass Spectrometry (ICP-MS). ICP-MS results have been incorporated into an existing ArcGIS geodatabase containing data from 77 previously analyzed samples collected in June and July of 2007. Element concentration trend maps have been produced for the entire county on ArcGIS using Kriging Interpolation and have been superimposed onto a St. Lawrence County bedrock map to determine the influence of the underlying bedrock on groundwater geochemistry and quality. Preliminary results suggest that the bedrock has a strong influence on groundwater geochemistry in many areas of St. Lawrence County. Examples include elevated B, Br, Li and Sr in dolostones with evaporitic layers; Na, Cl, S, and Zn associated with metamorphosed evaporate-carbonate hosted zinc deposits at Balmat; As along the Precambrian-Cambrian contact; and B and Li associated with world-class tourmaline deposits at Power’s Farm. In addition, Ca and Mg are abundant in groundwater derived from marbles and dolostones which underlie large areas of the county. Results have been compared to the Environmental Protection Agency’s (EPA) Maximum Contaminant Levels (MCLs) of primary and secondary standard regulations for drinking water. One sample exceeded the primary drinking water regulation for Arsenic while a total of thirty samples exceeded secondary drinking water standards: aluminum (n = 1), chlorine (n = 7), copper (n =5), iron (n = 1), manganese (n = 10), and total dissolved solids (n = 6). A pilot strontium isotope study was conducted on 13 of the water samples in January 2009 in an attempt to further constrain the source of various waters.
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