Climate controls on nitrate concentration variability in the Abbotsford-Sumas aquifer, British Columbia, Canada
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| Authors: | Graham, G; Allen, DM; Finkbeiner, B |
| Year: | 2015 |
| Journal: | Environ. Earth Sci. 73: 2895-2907 Article Link (DOI) |
| Title: | Climate controls on nitrate concentration variability in the Abbotsford-Sumas aquifer, British Columbia, Canada |
| Abstract: | Understanding the linkage between temporal climate variability and groundwater nitrate concentration variability in monitoring well records is key to interpreting the impacts of changes in land-use practices and assessing groundwater quality trends. This study explores the coupling of climate variability and groundwater nitrate concentration variability in the Abbotsford-Sumas aquifer. Over the period of 1992-2009, the average groundwater nitrate concentration in the aquifer remained fairly steady at approximately 15 mg/L nitrate-N. Normalized nitrate data for 19 individual monitoring wells were assessed for a range of intrinsic factors including precipitation, depth to water table, depth below water table, and apparent groundwater age. At a broad scale, there is a negative correlation between nitrate concentration and apparent groundwater age. Each dedicated monitoring well shows unique, non-uniform cyclical variability in nitrate concentrations that appears to correspond with seasonal (1 year) cycles in precipitation as well as longer-period cycles (5 years), possibly due to ENSO (El Nio Southern Oscillation) or the Pacific North American (PNA) pattern. These precipitation cycles appear to influence nitrate concentrations by approximately +/- 30 % of the critical concentration (10 mg/L NO3-N). Not all wells show direct correlation due to many complex local-scale factors that influence nitrate leaching including spatially and temporally variable nutrient management practices and soil/crop nitrogen dynamics (anthropogenic and agronomic factors). |
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