National Precipitation Chemistry Database from 200 Monitoring Stations

A 200-station network across the continental United States, Alaska, and Puerto Rico collects weekly precipitation samples for chemical analysis. The National Atmospheric Deposition Program established the network in 1978 to monitor acidic chemical deposition. Samples are analyzed for ions including hydrogen (pH), ammonium, calcium, sulfate, nitrate, chloride, and orthophosphate.

Use Cases

• Analyze trends in sulfate (SO4) and nitrate (NO3) ion concentrations over time to assess acid rain patterns.
• Model precipitation-weighted mean concentrations of ammonium (NH4) and calcium (Ca) for seasonal deposition studies.
• Correlate weekly precipitation amounts with chloride (Cl) and potassium (K) concentrations from individual samples.
• Compare field pH measurements with lab pH measurements to assess sample stability and quality assurance.
• Calculate deposition totals in kilograms/hectare for specific ions like orthophosphate (PO4) across annual summary periods.

Strengths

• 200-station monitoring network provides broad spatial coverage.
• Weekly sample collection enables high temporal resolution analysis.
• Quality assurance procedures are performed by a Central Analytical Laboratory.
• Data includes multiple measured ions (e.g., H, NH4, Ca, Mg, Na, K, SO4, NO3, Cl, PO4) and specific conductance.

Limitations

• Data availability lags by 6 months following sample collection.
• Network is rural and wet-only, limiting urban and dry deposition data.
• Sample data specifics like row count and file formats are unknown.

Provenance

Source

National Atmospheric Deposition Program/National Trends Network (NADP/NTN).

Collection Method

Weekly cumulative precipitation samples collected using Aerochem Metrics wet/dry collectors and analyzed at a Central Analytical Laboratory.

Time Range

Monitoring network established in 1978; ongoing data collection.

Freshness

Weekly data collection with a 6-month processing delay.

Geography

Continental United States, Alaska, and Puerto Rico.