- National Trends Network and Canadian Air and Precipitation
Monitoring Network (CAPMoN) stations are co-located at a site in
Quebec, Canada, and a site in Pennsylvania, U.S.
INTER-LABORATORY COMPARABILITY - Analytical laboratories
participate in interlaboratory proficiency tests to assess biases and
variability of analytical data.
NETWORK PRECISION - Precipitation chemistry collectors and
precipitation gages are operated side-by-side to determine overall
precision.
NETWORK BIAS - Samples of known composition are sent to field
site operators who transfer them to sample bottles and send them,
disguised as precipitation samples, to the laboratory for
(double-blind) analysis. Samples of known composition are sent to
field site operators who transfer them to sample collection buckets
after a dry sampling period. These buckets are handled and measured as
if precipitation had occurred, and the samples are sent to the
laboratory for (single-blind) analysis.
LABORATORY PRECISION - Samples are split, re-identified, and
sent for (double-blind) analysis.
LABORATORY BIAS - Samples of known composition are sent for
(double-blind) analysis by the laboratory QA officer.
LABORATORY QUALITY CONTROL - Standard laboratory practice
includes frequent analysis of reagent and procedural blanks, instrument
calibration check standards, control charts, random reanalysis,
targeted reanalysis based on ion balance calculations, and numerous
other internal controls.
LABORATORY PERFORMANCE REVIEWS – Periodic analytical
laboratory performance reviews by a team of peer scientists.
FIELD CHEMISTRY ACCURACY - Samples of known composition are
sent to all field site operators for (single-blind) pH and solution
conductance measurements.
FIELD SITE PERFORMANCE REVIEWS – Biennial field site visits
to test equipment operation, site operator performance, and adherence
to site installation rules.
DATA VERIFICATION & SCREENING - Data quality are ensured
through rigorous review, verification, and sample validation coding of
field and laboratory data.
