NWT Accession Number: NWT1912
Precipitation samples have been collected by the National Atmospheric Deposition Program's (NADP) National Trends Network (NTN) using the Aerochem Metrics Model 301 (ACM) collector since 1978. Approximately one-third of the NTN ACM collectors have been replaced with N-CON Systems, Inc. Model ADS 00-120 (NCON) collectors. Concurrent data were collected over 6 years at 12 NTN sites using colocated ACM and NCON collectors in various precipitation regimes. Linear regression models of the colocated data were used to adjust for relative bias between the collectors. Replacement of ACM collectors with NCON collectors resulted in shifts in 10-year seasonal precipitation-weighted mean concentration (PWMC) trend slopes for: cations (-0.001 to -0.007 mgL-1 yr-1 ), anions (-0.009 to -0.028 mgL-1 yr-1 ), and hydrogen ion (+0.689 meqL-1 yr-1 ). Larger shifts in NO3- and SO4 -2 seasonal PWMC trend slopes were observed in the Midwest and Northeast US, where concentrations are generally higher than in other regions. Geospatial analysis of interpolated concentration rasters indicated regions of accentuated variability introduced by incorporation of NCON collectors into the NTN.
NADP, atmospheric wet deposition, instrument bias, trend
Wetherbee, G.A., (2017) Precipitation collector bias and its effects on temporal trends and spatial variability in National Atmospheric Deposition Program/ National Trends Network data. Environmental Pollution , DOI: 10.1016/j.envpol.2016.1
This material is based upon work supported by the National Science Foundation under Cooperative Agreement #DEB-1637686. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necesarily reflect the views of the National Science Foundation.
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