The Canadian Air and Precipitation Monitoring Network (CAPMoN) was established in 1988 to determine temporal trends and spatial distribution for wet deposition and provide estimates of dry deposition at regional representative sites in Canada.   Over the last decade ammonia, the primary alkaline gas in the atmosphere has been added to the suite of nitrogen species measured during a few select studies in part to estimate the contribution of ammonia to the total nitrogen dry deposition flux.  Continuous measurements of ammonia have been conducted using both a Picarro cavity ring down analyzer and a modified Thermo 42i trace level instrument (by difference)

with detection limits of approx. 100 pptv or better.  In addition, two week integrated samples were collected using Radiello ammonia passive samplers in conjunction with  NADP’s Ammonia Monitoring Network (AMoN).  Measurements of ammonia have been typically determined to be on the order of a few ppbv and have ranged from being near or below detection limit during the winter to significantly elevated levels associated with agricultural activities and forest fires.  During some of these studies, the ammonia monitoring has been accompanied with continuous measurements of NO, NO₂, and NO_y and daily integrated values of HNO₃, particle nitrate and particle ammonium from CAPMoN’s filter packs.  The comparability of the various ammonia monitoring methods, seasonal and diurnal variations of the ambient ammonia mixing ratios, and the relative contribution of ammonia to the total nitrogen dry deposition will be presented.