Deposition rates for sulfur and nitrogen to a hardwood forest in Northern Connecticut, U.S.A.

Abstract

Wet and dry deposition fluxes in north-central Connecticut were estimated using a three-stage filterpack system and a dry deposition inferential model (DDIM). When compared with measurements from northeastern U.S.A. sites of the E.P.A. National Dry Deposition Network (NDDN), north-central Connecticut atmospheric concentration values generally were higher than Hubbard Brook, NH and lower than West Point, NY. Total nitrogen deposition for 1990 was 8.78 kg ha-1 with 60.0% dry deposition and for 1991 was 7.24 kg ha-1 with 45.6% dry. Total sulfur deposition for 1990 was 10.31 kg ha-1 with 26.6% dry and for 1991 was 12.90 kg ha-1 with 32.6% dry. Quarterly wet plus dry fluxes for both nitrogen and sulfur showed a second quarter peak over the two and a half year study period (from July 1989 to January 1991). Dry deposited nitrogen exceeded the wet component during four of the 10 quarters whereas wet deposited sulfur always exceeded the dry deposition. Possible errors in the DDIM calculations due to the location of the measurements in a forest clearing are discussed. © 1994.