Comparison of long-term precipitation chemistry measurements at the Hubbard Brook Experimental Forest, New Hampshire

From 1978 through 1989, a wet-only precipitation collector operated for the National Atmospheric Deposition Program, an independant wet-only collector, and a bulk precipitation collector were co-located at the Hubbard Brook Experimental Forest (HBEF) in central New Hampshire. A second bulk precipitation collector was maintained at another location within the HBEF. There were statistically significant differences between the chemistry from co-located wet-only collections for Ca2+, K+, NH4+, pH, and NO3-. The differences for K+ and pH though statistically significant were very small but consistant. The differences for Ca2+ were related to early contamination problems, and differences in NH4+ and NO3- were related to episotic events. Bulk precipitation was significantly richer in K+ than wet-only precipitation. There were no differences for any ions between the bulk collections at the two locations. While there were minor differences, after 1981 when the contamination problems had been resolved, data from all collectors at all locations adequately characterized the precipitation chemistry of the site.