Progress 10/01/02 to 09/30/06
Outputs
The hypothesis that the Deuterium and O-18 isotopes can be used to distinguish between ocean water and ground-water contaminated with deicing salt is not supported by the data collected during this project. The large range of isotopic values measured in the precipitation completely overlap the isotopic values measured in ground-water samples, and nearly reaches the isotopic composition of sea water. It is difficult to distinguish between a mixture of sea water and ground water, and precipitation tainted with road salt based on isotopic signature alone. Ground-water samples from different locations are characterized with different average isotopic signatures, further confounding the use of isotopes to identify ground water and sea water mixtures. Different isotopic signals measured in ground water at one location may be related to mixing between different ground-water systems. We conclude that O-18 and Deuterium isotopes are not an effective tool for distinguishing
different sources for salt (NaCl). The data collected for this project were useful in other applications. The isotopic data collected for this project was used in assessing the oxygen source for sulfate in ground water with high arsenic concentrations. Oxyen isotope data indicate that atmospheric oxygen is an important oxygen source for sulfate ions measured in the ground water collected from fractured bedrock aquifers near Northport, Maine.
Impacts
This research suggests that the isotopes of water are not a useful tool for discriminating between different sources of salt in ground water. Data collected for this project characterizes the isotopic composition of ground water and precipition in central Maine.
Publications
- Reeve, A. 2002. Arsenic geochemistry in bedrock aquifer, Northport. Maine Arsenic in New England: A multi-disciplinary scientific Conference. Manchester, New Hampshire.
- Kreutz, Karl. (2002) Hydrogen isotopes, ice cores, and Maines hydrologic cycle. University of Maine Dept. of Earth Science Seminar.
- Lipfert, Gail. William Sidle, Andrew S. Reeve and Robert A. Ayuso. 1997 In Review. Relationship of arsenic concentrations to sulfur and oxygen isotopes in a fractured-bedrock ground-water system.
- Lipfert, G., A. Reeve, W. Sidle, R. Marvinney. 1996. Geochemical patterns in an arsenic tainted, fractured-bedrock system in Northport, Maine, USA. Applied Geochemistry
- Kretz, Karl. 2005. Tracing Maines hydrologic cycle using stable isotopes. Climate Change Institute Agassiz Symposium.
- Kreutz, Karl. 2003. University of Maine Chemistry Department Seminar. Using stable isotopes to trace the hydrologic cycle.
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Progress 10/01/04 to 09/30/05
Outputs
Precipitation samples collected near Sebec Lake, Maine had an isotopic composition that ranged from about -33 to -2 18 O and -260 to -9 Deuterium. A linear regression on this data results in the equation: D = 7.8 * 18 O + 9.2 which is similar to the equation for the global meteoric water line: D = 8 * 18 O + 10. Isotope values measured in ground-water samples from a variety of areas range from about -12 to -6 18 O and -80 to -35 Deuterium, and also plot along the global meteoric water line. The hypothesis that the Deuterium and Oxygen isotopes can be used to distinguish between ocean water and ground-water contaminated with deicing salt is not supported by the data collected during this project. The large range of isotopic values measured in the precipitation completely overlap the isotopic values measured in ground-water samples, and nearly reaches the isotopic composition of sea water. It is difficult to distinguish between a mixture of sea water and ground water,
and precipitation tainted with road salt based on isotopic signature alone. Ground-water samples from different locations are characterized with different average isotopic signatures, further confounding the use of isotopes to identify ground water and sea water mixtures. Different isotopic signals measured in ground water at one location may be related to mixing between different ground-water systems. We conclude that 18 O and Deuterium isotopes are not an effective tool for distinguishing different sources for salt (NaCl).
Impacts
This research demonstrated that Deuterium and Oxygen water isotopes are not useful for discriminating between possible sources of salt in ground water.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
Precipitation samples collected weekly from August 2002 through August 2004 at Sebec Lake were analyzed for H and O isotopes. These data represent the first continuous time-series characterization of stable water isotopes in Maine precipitation, and form the basis of our initial interpretations of groundwater isotope hydrology. The Sebec Lake dataset displays large seasonal variability related to a combination of atmospheric temperature and moisture source effects, with very depleted isotope values occurring during Fall and Winter of 2002 and 2003. The measured isotopic composition of these samples is comparable to values observed in polar and high-elevation regions, suggesting significant fractionation related to meteorological conditions. We are in the process of correlating meteorological data obtained from the Sebec Lake station with the isotope data to elucidate the relevant processes. In addition, precipitation sample collection has begun at two additional sites
in Caribou and Gray. Groundwater samples collected thus far from three sites: construction and demolition debris sites in Old Town and West Forks, and near an arsenic cluster near Bayside. Isotope data are broadly consistent with the precipitation data, with more depleted values occurring at the northernmost site (West Forks). Comparison of the groundwater data with both the meteoric water line and the Sebec Lake precipitation data suggests fractionation processes that are site-specific, possibly occurring during groundwater infiltration and transport. We are continuing with groundwater isotope analyses from several additional sites to obtain a better spatial characterization and to investigate salt effects.
Impacts
Contamination of ground water by salt originates from many sources including road salt, landfill leachate, and sea-water intrusion. Isotopes are a promising tool for discriminating between different sources of salt measured in groundwater. We are evaluating the application of isotopes for distinguishing between road salt, saline landfill leachate and natural sea water.
Publications
- No publications reported this period
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Progress 10/01/02 to 09/30/03
Outputs
A suite of water samples from 10 drilled wells was collected in Winthrop, Maine in August/September 2003 by Jay Lindsey (High School teacher in Winthrop) after discussions with Norton. These samples follow a sampling of many of the same wells in May of 2003 by Lindsey. Evaluation of the earlier data set as well as data over the last two decades from the same area suggested that many of the drilled wells had been contaminated by an obvious surface salt supply associated with the Maine Department of Transportation salt storage pile. One domestic well was replaced with a deeper well (ca. 400 feet) which apparently penetrated trapped late deglacial sea water. The bottom of that well is approximately 100 feet below the marine limit of about 260 feet above sea level. Dilution of this trapped sea water is on the order of 7:1, fresh water:salt water. We are evaluating the isotopic chemistry (18-O and D) to see if a mixing model based on chemistry is demonstrable based on
isotope ratios. Water samples from monitoring wells near two construction and demolition debris (CDD) landfills have been collected, in conjunction with the Maine Dept. of Environmental Protection and an environmental consulting firm. Both of the landfills are associated with salt-rich plumes. Ground-water samples have been submitted for oxygen, hydrogen, sulfur and strontium isotope analysis and we await the analytical results.
Impacts
Contamination of ground water by salt originates from many sources including road salt, landfill leachate, and sea-water intrusion. Isotopes are a promising tool for discriminating between different sources of salt measured in groundwater. We are evaluating the application of isotopes for distinguishing between road salt, saline landfill leachate and natural sea water.
Publications
- No publications reported this period
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