Identifying ground-water and evaporated surface-water interactions near
a landfill using deuterium,18oxygen, and chloride,
Norman, Oklahoma
By Jamie L. Schlottmann, Martha A. Scholl, and Isabelle M. Cozzarelli
Abstract
The composition of water discharging to a small wetland (the slough) downgradient
from a closed municipal landfill was investigated using chloride concentration
and enrichment in deuterium and 18oxygen to determine
the source waters for the slough. Potential source waters include native alluvial
ground water, shallow recent recharge to the alluvium from precipitation,
and leachate-contaminated ground water. Effects of evaporation from the slough
on those potential source waters were calculated to determine source waters
for the slough.
Deuterium and chloride are enriched in the landfill leachate relative to
the native ground water. Deuterium and 18oxygen have
a great range and chloride concentration is low in recent recharge relative
to native ground water. The initial water isotopic composition of the slough
was estimated based on the range of temperature and humidity conditions under
which the water was evaporated. The amount of evaporation of the potential
source waters was then estimated by the change in deuterium, 18
oxygen,
and chloride values of the slough from those in potential source waters. Results
of calculating evaporation of potential source waters suggest the slough receives
primarily uncontaminated native ground water but also some landfill leachate
and the contribution from these sources varies over time. One of three slough
samples had a suggested initial composition of leachate-contaminated water,
which was diluted approximately 70 percent by recent recharge prior to entering
the slough. Suggested initial compositions of other two samples included native
ground water only.