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NTN Lab Methods

At the Central Analytical Laboratory (CAL), the concentrations of the important inorganic chemicals in precipitation are analyzed. These chemicalsor analytesinclude acidity (measured as pH), sulfate, nitrate, ammonium, chloride, and base cations.

The data are checked to ensure their quality, and special codes are applied to help in interpreting the data. These sample validity codes indicate the quality of the samplefor instance, whether it was collected according to standard protocols and whether there is any sign of contamination.

After this initial data processing, the data are sent electronically to the NADP Program Office, which performs further checks of accuracy and completeness. The entire data record is confirmed as being consistent with standard NTN procedures and documentation. Sophisticated data processing programs are run to detect discrepancies in the coding of the samples validity and in the completeness of each sites data records. Any such discrepancies are carefully screened and resolved.

Only after data verification is complete is the sample record entered into the NADP database, ready for distribution to the public and inclusion in NADP publications.