Sample Archive Disposal

The NADP Central Analytical Lab will begin disposal of NTN, AIRMoN and AMoN archived samples which have exceeded our sample retention policy. The following samples are available prior to disposal:

  • NTN Archive Samples: 10 to 60 mL filtered precipitation (stored at 4°C); Samples from 2014 and 2015
  • AIRMoN Archive Samples: 10 to 200 mL unfiltered precipitation (stored at 4°C); Samples from 2018
  • AMoN Extracts - ~5 mL of passive ammonia sampler extract (stored frozen); Samples from 2018

All requests are subject to pricing and conditions set by NADP. Please contact the NADP Program Coordinator, David Gay at 608-263-9162 or at for sample archive requests. All unrequested samples will be removed on March 1st, 2021 and these samples will no longer be available for request.

NADP Foundation established

NADP establishes a charitable foundation to help support the program mission.

Br Notification

Notification: The NADP Central Analytical Laboratory (CAL) determined that web-published bromide data from January 2012 through June 2018 have a known or suspected bias caused by the presence of oxalate in the precipitation. Motions to remove these data from the NADP website and discontinue bromide as an official NADP analyte (due to >80% non-detects) were presented to the NADP Executive Committee on May 17, 2019 and were approved. This note serves as notification that these motions have been executed - all bromide data, including maps, was removed from the NADP website on October 15th, 2019; and as of June 1st, 2019 the NADP CAL is no longer quantifying bromide. Preliminary, summary and individual sample reports will no longer include bromide results (though for a period of time the published data file format will continue to include the bromide column, but without analytical results). Bromide data from June 2018 through June 2019 (which is valid) and the larger bromide data set will be archived and made available upon request. A link to documents providing background on this bromide issue will be placed on the NADP website. Please contact David Gay at with any questions and data requests.

Nr Deposition Science Needs White Paper

NADP's Total Deposition Science Committee (TDep) has released a white paper, Science needs for continued development of total nitrogen deposition budgets in the United States".

CAL Readiness Verification Report

The CAL Readiness Verification Report has been released

Happy 40th Anniversary to NADP!

The very first NADP samples on July 5, 1978 were from: NC25, Coweeta in Macon, NC; WV18, Parsens in Tucker, WV; MN16, Marcell Experimental Forest in Itasca, MN.

NADP has moved

The NADP Program Office (PO) and Central Analytical Lab (CAL) moved in 2018 from the University of Illinois (U of I) to their new home at the University of Wisconsin's State Laboratory of Hygiene (WSLH) in Madison, WI. The Mercury Analytical Lab (HAL) moved from Frontier-Eurofins in Seattle, WA to the WSLH in 2019.

NADP Impact Statement

The NADP is the State Agriculture Experiment Station (SAES) National Research Support Program 3 (NRSP-3). SAES recently published a 2-page Impact Statement that highlights NADP’s accomplishments for the period 2009-2014.

Total Deposition Maps now Available

NADP has just released a new series of maps, which are estimates of dry plus wet deposition for sulfur and nitrogen. The maps are based on a new hybrid method of determining total deposition, which was developed within the NADP Total Deposition Science Committee (TDEP) . Check out the website for more details and to see the maps!

Litterfall Mercury Monitoring Initiative

The National Atmospheric Deposition Program (NADP) has a new litterfall mercury monitoring initiative to complement the Mercury Deposition Network (MDN) monitoring for mercury in precipitation and the Atmospheric Mercury Network (AMNet) monitoring for mercury in air