Cation and Anion Dynamics in a Partially Developed Watershed Author: Joshua Dunn and Dr. Michele Hluchy (Advisor), Alfre

1. 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 < 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.

2. pH Seasonal variations in pH reflect seasonal differences in ion concentrations. The average pH of precipitation was 4.62, which is slightly higher than the previously observed average of 4.0. pH also becomes less acidic with depth. As water percolates through the soil zone and into groundwater acidity decreases which also reflects variability in ion concentrations with depth. Vermiculite Vadose zone mineralogy is generally uniform with depth. The only exception is the illite and vermiculite peaks which gradually increase with depth. Calcite Peak Stream Water Soil Moisture Bulk soil mineralogy is also uniform with depth. However, a calcite peak at around 29 degrees 2 theta (around 8 feet in depth) which may explain the high concentrations of calcium in the shallow ground water. Throughout the study period stream water had lower ion concentrations than groundwater. Ion concentrations remain mostly constant for most of the year, but sodium and calcium increase during the spring. This increase is probably due to the melting and run-off of salt-rich snow. Total ion concentrations were high during the winter and summer months. Total ion concentrations during the spring were low due to dilution by snowmelt. Calcium is the dominant ion in soil moisture and is the cause for reduction of acidity brought in by precipitation. 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)