Predicting Redox Conditions in Groundwater at a Regional Scale

Defining the oxic-suboxic interface is often critical for determining pathways for nitrate transport in groundwater and to streams at the local scale. Defining this interface on a regional scale is complicated by the spatial variability of reaction rates. The probability of oxic groundwater in the C...

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Bibliographic Details
Published in:Environmental science & technology 2015-08, Vol.49 (16), p.9657-9664
Main Authors: Tesoriero, Anthony J, Terziotti, Silvia, Abrams, Daniel B
Format: Article
Language:English
Subjects:
Environmental Monitoring - methods
Geology
Groundwater
Groundwater - analysis
Groundwater - chemistry
Maryland
Models, Theoretical
Nitrates - analysis
Nitrogen - analysis
Oxidation-Reduction
Probability
Regression analysis
Rivers
Simulation
Soil
Virginia
Watersheds
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Summary:Defining the oxic-suboxic interface is often critical for determining pathways for nitrate transport in groundwater and to streams at the local scale. Defining this interface on a regional scale is complicated by the spatial variability of reaction rates. The probability of oxic groundwater in the Chesapeake Bay watershed was predicted by relating dissolved O2 concentrations in groundwater samples to indicators of residence time and/or electron donor availability using logistic regression. Variables that describe surficial geology, position in the flow system, and soil drainage were important predictors of oxic water. The probability of encountering oxic groundwater at a 30 m depth and the depth to the bottom of the oxic layer were predicted for the Chesapeake Bay watershed. The influence of depth to the bottom of the oxic layer on stream nitrate concentrations and time lags (i.e., time period between land application of nitrogen and its effect on streams) are illustrated using model simulations for hypothetical basins. Regional maps of the probability of oxic groundwater should prove useful as indicators of groundwater susceptibility and stream susceptibility to contaminant sources derived from groundwater.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.5b01869