Table DR-2- Sampling Details
Water samples were collected over a 3 year period from private rural ground water wells.
Wells are ~15 cm in diameter and steel-cased through surficial deposits to bedrock (depths of
which are provided in Table 1, data appendix/ repository), and then open to the bedrock aquifer
below the base of casing. Locations of wells sampled are shown in Figure 1.
Water was sampled using residential production pumps and if water treatment systems
were present, they were bypassed. Samples were collected in acid-washed, High Density
Polyethylene (HDPE) bottles and stored on ice for delivery to analytical laboratories. A
calibrated YSI multiprobe was used to measure water temperature, conductivity, pH, oxidationreduction potential (ORP), and % dissolved oxygen (DO) in the field – samples were collected
once all parameters had attained steady values.
Table DR-3- Analytical Methods and Precision for Groundwater Geochemistry
Groundwater samples were analyzed for gross alpha (GA) radiation, 226radium, 228radium, and
uranium at the Vermont Department of Health Laboratory in Burlington, Vermont. GA was
analyzed via the EERF 00-02 method, 226Ra by the SM 7500 Ra-B method, 228Ra by the EERF
Ra-05 method, and U by the EPA 200.8 method.
Concentrations of metals and anions were analyzed at the Vermont Department of
Environmental Conservation Laboratory in Waterbury. Samples were acidified and digested
before analysis. The methods by which all metals and anions were determined are shown below.
Representative precision, accuracy, and detection limit data are shown in Table 2.
1) Al, Sb, As, Ba, Be, Cd, Ca, Cr, Co, Cu, Fe, PB, Mg, Mn, Mo, Ni, K, Se, Ag, Na, Sr,
Tl, Total Calculated Hardness, U, V, and Zn – EPA 6020 method (Inductively Coupled
Plasma Mass Spectrometry (ICP-MS)).
2) Hg – EPA 245.1 method.
3) Cl- – either the EPA 300.0 or SM 4500CL-G.
4) SO4-2 and NO3-1 – EPA 300.0.
5) P – SM 4500-PH.
6) SiO2 – SM 4500 SiO2 F.
7) Alkalinity – SM 2320B.
Representative Quality Control Run on Water Analyses by Vt DEC Lab
QC
%
RPD
Test
Type
Recovery
% Recovery Limits RPD
Limits
103
80-120
U
MS
103
80-120
MSD
0
8
80-120
MS
106
Na
101
80-120
MS
Mg
97
80-120
MS
K
124
80-120
MS
Ca
97
80-120
MS
Ba
95
80-120
1
8
MSD
86
80-120
MS
Cu
87
80-120
1
8
MSD
92
80-120
MS
Fe
92
80-120
0
8
MSD
91
80-120
MS
Mn
92
80-120
1
8
MSD
100
80-120
MS
Mo
100
80-120
1
8
MSD
101
80-120
MS
Pb
101
80-120
0
8
MSD
101
80-120
MS
Sr
101
80-120
0
8
MSD
MS= Matrix Spike; MSD=Matrix Spike Duplicate; RPD= Relative %
Deviation
Table DR-4- Analytical Methods and Precision for Whole-Rock Geochemistry
Rock samples were cleaned of weathering rinds with a water-cooled rock saw, passed
through a ceramic Spex Jaw Crusher and milled into powder using a Shatterbox. Powders were
ignited at 1000 oC to determine loss-on-ignition (LOI), fused at 1050 oC in graphite crucibles
with lithium metaborate flux, and dissolved in 10% HNO3. Concentrations of the 10 major
elements (SiO2, Al2O3, TiO2, MgO, Fe2O3, CaO, Na2O, K2O, MnO, and P2O5) and the trace
elements Ba, Co, Cr, Cu, Ni, Sc, Sr, V, Y, Zn and Zr were determined on a Thermo Elemental
IRIS 1000 DUO inductively coupled plasma–atomic emission spectrometer (ICP-AES) at
Middlebury College. Concentrations of the 14 rare earth elements and of numerous other trace
elements including Rb, Th, and U were determined by inductively coupled plasma–mass
spectrometry (ICP-MS) at Acme Analytical Laboratories, Vancouver, Canada. Major element
compositions of 3 samples were determined by X-ray fluorescence (XRF) at XRAL laboratories
in Ontario, Canada. Analytical precision of ICP-AES analyses was evaluated by running
standard solutions that encompassed compositional ranges as quality checks before and after
each 5-sample run, while accuracy was measured by comparison to U.S. Geological Survey
certified standards G2 and MRG-1 (Table 4).
Uncertainties determined by replicate analyses and comparison to USGS standards for
SiO2, Al2O3, Fe2O3 and CaO are + 3%, whereas for TiO2, MnO, MgO, K2O
and Na2O, uncertainties are + 10%. Uncertainties for trace elements are + 10%. Whole rock
geochemical analyses were normalized to 100% on an anhydrous basis, and statistical
calculations involving concentrations of elements lower than detection limits were performed
using the value of the limit (Cloutier et al., 2006).
Mineralogical and textural characteristics of selected samples were analyzed by
transmitted light microscopy and by scanning electron microscopy (SEM) paired with energy
dispersive X-ray (EDX) elemental analysis in a Zeiss DSM 940A at Middlebury College. In
some cases analyses were performed in back-scatter electron (BSE) mode to enhance
identification of U- and Th-bearing minerals (e.g. zircon, apatite, sphene and monazite).