GROUNDWATER FLOW AND GEOCHEMISTRY AT GREENWOODS PRESERVE, CENTRAL NEW YORK

This study attempts to link groundwater geochemistry to shallow (<50 m depth) flow paths and surface waters in a case study in central upstate New York. We measured elemental water chemistry and bulk parameters (total dissolved solids, electrical conductivity, salinity, temperature and pH) in various water body types (lake, stream, and well) in an upland region over an areal extent of about 5 square km. The project area is underlain by Devonian sedimentary units, namely the Moscow formation which overlies the Panther Mountain formation which in turn overlies the Marcellus shale formation. We tested the following hypotheses: Does groundwater rise from a deeper aquifer along a regional fracture? How well do elemental concentrations in groundwater reflect underlying geology? Can water body type be inferred solely from elemental concentrations and/or bulk parameters? We sampled water in five hand-dug shallow wells, three deeper drilled wells, two bog locations and several streams repeatedly from May 2013 to November 2013. 50-60 elements were analyzed including major, minor trace and rare earth elements. Elemental concentrations were determined using inductively coupled plasma-mass spectroscopy (ICP/MS) and chemical titrations. We mapped fracture patterns in bedrock exposures. While good evidence exists that a major bog lies along a regional fracture, we find no clear evidence that groundwater rises from a deeper aquifer to shallower aquifer in our study area. We do find that elemental concentrations in groundwater samples reflect underlying geology, and that total dissolved solids vary systematically by water body type: bog is the lowest, followed by shallow wells, lakes, streams, and deep drilled wells in order of increasing concentration. There is, however, significant variation in geochemical fingerprints between wells, suggesting that locally, water-rock reactions along groundwater flow paths develop a characteristic suite of dissolved elements. Surface water bodies are more similar to shallow (<10 m) wells than deeper wells (~47 m deep).