Cation and Anion Dynamics in a Partially Developed Watershed

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Cation and Anion Dynamics in a Partially
Developed Watershed Author Joshua Dunn and Dr.
Michele Hluchy (Advisor), Alfred University
Abstract This is a study that focuses on the
differences in anion and cation concentrations in
water, soil, and aquifer material sampled from
the upper Canacadea watershed in Alfred NY. I
studied the dynamics of ions in order to
ascertain how they affect the overall
biogeochemical budget of the study area.
Methods We collected data continuiosly using
sensors and dataloggers to measure 1) ground
water levels in two aquifers 2) discharge of the
Canacadea Creek in the village of Alfred 3)
precipitation amount and intensity and 4) air,
soil and water temperature. The precipitation
(ppt) was collected from four strategically
selected sites through a funnel
collector. Tension lysimeters were used to
collect soil moisture from the depths of 30cm and
60cm at the same sites as ppt. Samples are taken
weekly, and the lysimeters are evacuated to 60
psi after collection. The lysimeters are
constructed from a PVC pipe with a porous cap.
Ground water sampling is done through a nest of
three piezometers placed two inches from one
another. Samples are collected weekly from the
piezometers from depths of 12, 24, and 34 feet.
Ground water, precipitation, and stream water
collection began three years ago, and lysimeter
collection stated October 1, 2001. Every sample
is tested for pH immediately after collection.
Two pieces of analytical equipment, an ion
chromatograph and an atomic absorption
spectrophotometer, were used to determine the
concentration of common inorganic anions and
cations in our water samples. Soil cores were
obtained during the installation of each
piezometer and pumping well. Also, soil samples
were taken from the depths of 10cm, 20cm, 30cm,
and 40cm at each of the precipitation and
lysimeter collection sites. All samples were
powdered in a ball mill and the lt two micron size
fraction was separated from samples taken at the
precipitation sites and prepared for preferred
orientation. Mineralogy was determined by X-ray
diffraction.
Introduction During the summer of 1999, we began
a comprehensive sampling and analysis program of
the Canacadea Creek watershed. This was the
beginning of what we plan to be a long-term
study, which continued throughout several
academic years (99-03). The watershed, as
we define it, encompasses all of the land area
(1.2 square miles) that ultimately contributes
water to the Canacadea Creek upstream of the
Alfred University Environmental Studies Program
stream gauging facility (See Map). As part of
the study, we collected precipitation, soil
moisture, ground water and stream water and
analyzed them for several dissolved constituents,
including sulfate and nitrate, which are the
principal anionic components of acid
precipitation. Also, we will analyze the sample
for various cations, such as calcium, sodium, and
magnesium.
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Mineralogy
RESULTS
Illite
Groundwater
Precipitation
40 cm
10 cm
Calcium and sodium are the dominant ions in the
shallow well. Sodium concentrations peak during
the winter months due to contamination by road
salt. The high concentration of calcium is
likely due to soil moisture moving downward into
the ground water zone. Sodium and calcium
decrease rapidly with depth. Nitrate increases in
the upper soil horizon then decreases with depth.
The increase of nitrate is possibly due to
microbial nitrification. Sulfate decreases in
the upper soil horizon and then increases with
depth.
High acidity during the spring is associated with
high levels of sulfate. Also, periods with low
levels of sulfate and high levels of calcium are
associated with low acidity.
30 ft
0 ft
Conclusions
The pH of precipitation is directly affected by
ionic concentration. For example, pH becomes
more acidic as sulfate and nitrate concentrations
increase. Ion concentrations in soil moisture
are strongly affected by factors such as
precipitation chemistry, soil mineralogy,
snowmelt, and biologic activity. The appearance
of calcite in the soil from the depth of 8 feet
coincides with an increase in calcium in shallow
ground water. Tritium analysis proves that the
lower aquifer is at least fifty years older than
the upper aquifer. However, there is no
conclusive evidence that the aquifers are
chemically independent. Some mixing may occur.
This study did not sufficiently examine the
mineralogy of the area, for analysis was broad
and inconclusive. Further research is needed to
understand the processes involved in the
interaction of ground water and clay/soil
minerals.
Acknowledgements Michele Hluchy (Advisor),
Garrett McGowen (Advisor), Adam Gardner, X-ray
Group (SUNY School of Ceramics at Alfred U.),
Jeanne Wilson, Dean Perry, Patricia Mulligan and
Sondra Stephens (IT support), Doug Clarke (IC
Tech)