Seasonal Atmospheric Nitrate and Ammonium Deposition along an Elevation Gradient in the Colorado Front Range using Ion Exchange Resin Columns (2018-2019)
Dates
Publication Date
2021-02-11
Start Date
2018-01-30
End Date
2019-12-16
Citation
Repert, D.A., Murphy, S.F., Halamka, T.A., Hill, M.M., Heindel, R.C., and Clow, D.W., 2021, Seasonal Atmospheric Nitrate and Ammonium Deposition along an Elevation Gradient in the Colorado Front Range using Ion Exchange Resin Columns (2018-2019): U.S. Geological Survey data release, https://doi.org/10.5066/P9XW4TM8.
Summary
Atmospheric deposition of reactive nitrogen (Nr) due to human activities can have measurable effects on ecosystem processing and export of nutrients, groundwater and surface-water quality. Rates of Nr deposition to lower-elevation forests immediately adjacent to the Denver/Boulder urban area, however, have only recently been measured. The focus of this study was to determine the extent of urban and agricultural N pollution transport to the Colorado Front Range. In conjunction with the Network for Urban Atmospheric Nitrogen Chemistry (NUANC) and the National Atmospheric Deposition Program (NADP), we measured wet-plus-dry Nr deposition and evaluated spatial and seasonal variations in N deposition along an elevational gradient (1603 to [...]
Summary
Atmospheric deposition of reactive nitrogen (Nr) due to human activities can have measurable effects on ecosystem processing and export of nutrients, groundwater and surface-water quality. Rates of Nr deposition to lower-elevation forests immediately adjacent to the Denver/Boulder urban area, however, have only recently been measured. The focus of this study was to determine the extent of urban and agricultural N pollution transport to the Colorado Front Range. In conjunction with the Network for Urban Atmospheric Nitrogen Chemistry (NUANC) and the National Atmospheric Deposition Program (NADP), we measured wet-plus-dry Nr deposition and evaluated spatial and seasonal variations in N deposition along an elevational gradient (1603 to 3159 meters) from plains to subalpine ecosystems west of Boulder, Colorado. Ion-exchange-resin (IER) columns with attached collector funnels were deployed at 5 locations along the elevational gradient during spring, summer and fall seasons to measure bulk (wet-plus-dry) N deposition. IER columns were collected at ~2-month intervals in 2018 and 2019 then extracted with KCl and analyzed for nitrate plus nitrite and ammonium concentrations. Results were blank corrected using sealed field IERs deployed to measure potential contamination due to handling. The mass of nitrogen species on the column was calculated and normalized to mass per unit area per day using the surface area of the funnel opening. Snow buckets were employed periodically during the winter to obtain estimates of deposition during snow falls. Results were normalized to mass per unit area per day using the surface area of the snow bucket opening.
This data release contains nitrate and ammonium data collected from ion exchange resin columns (IERs) installed along an elevation and land cover gradient on the eastern slope of the Colorado Front Range. An objective of the study was to compare seasonal bulk atmospheric nitrogen deposition at sites along this gradient as well as to compare these results to those obtained by wet deposition samplers installed by the National Atmospheric Deposition Program (NADP). Results enabled an estimation of atmospheric nitrogen dry deposition.
Preview Image
IER columns installed at Sugarloaf field site, May 2019