Lin, Ming-chung. 1991. Seasonal and Annual Patterns of Precipitation Chemistry in the Northeastern United States. M.S. Thesis, State University of New York, College of Environmental Science and Forestry, Syracuse, 156pp.

Abstract: Precipitation chemistry data for the period 1979-1989 obtained from weekly collected samples at Huntington Forest, NY and five other NADP/NTN sites in the northeastern U.S. were examined to explore the monthly and seasonal patterns as well as longer temporal trends of nine major ions.

Warm season concentration and deposition peaks were found for SO42- and H+, while late spring and early summer peaks existed for NH4+, Ca2+, Mg2+, K+, suggesting that emissions, transformation processes and precipitation depth may contribute to deposition variation. No significant monthly pattern was found for No3 -, however the NH4+/NO 3- ratio shows a significant maximum in June at all sites.

Trend analysis using the seasonal Kendall's test and the slope t-test indicated that SO42- and base cation (Ca2+, Mg2+, K+ and Na+) concentrations and fluxes decrease during the period 1978-1989. Only at Aurora did H+ and NO3 - significantly decrease. At that site the background emissions were also high. The lack of consistent relationships between SO4 2- and H= temporal trends may be due to the decrease of base cations accompanying SO42- deposition reduction. Regression models predict holding base cations constant and reducing one unit of SO42- will reduce H+ by 0,75 unit while holding SO42- constant and reducing one unit of base cations will increase H+concentration by 0.90 unit.