25 Undergraduate Research in the Geological Sciences I (Posters)

A PRELIMINARY HYDROGEOCHEMICAL ASSESMENT OF THE LITTLE CHAZY RIVER, NORTHEASTERN NEW YORK

Paper number: 25-18
Program: THEME SESSIONS
Time: 8:00 AM – 6:00 PM

Authors

Abstract

The Little Chazy River (142 km2) originates in the Adirondack foothills and flows eastward to Lake Champlain. The headwater region is underlain by the Cambrian Potsdam Sandstone and Precambrian meta-anorthosite and is covered by thin (<3m thick), glacial soils. Included in the upland portion of the watershed is Altona Flat Rock, a broad area of exposed sandstone bedrock discontinuously veneered (<0.3m thick) with organic litter and humus. The lower, nearly 70% of the watershed lies in the Champlain Lowland, a broad, low relief region underlain by Cambro-Ordovician sandstone and carbonate rocks and Late Pleistocene glacial, lacustrine and marine sediments. Land cover in the lowlands is a mix of forests and agricultural land and includes two small villages. The mainstream has two principal tributaries, Farrell Brook (23.5 km2) and Tracy Brook (26.9 km2). The purpose of this study was to relate stream flow and water chemistry to the physiography, geology, land cover and land use in the watershed.

Stream discharge and water chemistry were monitored at ten temporary stations, six along the mainstream and two on each tributary, and at a gauged intermittent seep on Altona Flat Rock. The seep is typical of runoff generated from the exposed sandstone pavements. Stream water pH, specific conductance, alkalinity and phosphorus content generally increased downstream in a manner consistent with changes in geology and land use. A Piper Plot of major cations and anions shows that Ca and Mg are the dominant cations and bicarbonate is the dominant anion in surface waters. The relative proportions of the major ions do not vary significantly throughout most of the watershed. Runoff from the Flat Rock sandstone pavement, however, is acidic (mean pH=4.20) with high relative proportions of Al, Fe, and Ca, negative alkalinities (mean alkalinity=-64 ueq/L) and anions dominated by sulfate.

The National Science Foundation Research Experiences for Undergraduates (REU) Program (EAR 0139132) provided support for this study.