HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Alewell, C. Articles by Krouse, R. Search for Related Content PubMed Articles by Alewell, C. Articles by Krouse, R. Agricola Articles by Alewell, C. Articles by Krouse, R.

Assessing the Origin of Sulfate Deposition at the Hubbard Brook Experimental Forest

BITÖK, University of Bayreuth, 95440 Bayreuth, Germany.

M. J. Mitchell

College of Environmental Science and Forestry, SUNY, Syracuse, NY 13210.

G. E. Likens

Institute of Ecosystem Studies, Millbrook, NY 12545.

R. Krouse

Dep. of Physics and Astronomy, Univ. of Calgary, Calgary, AB T2N 1N4, Canada.

^* Corresponding author (christine.alewell{at}bitoek.uni-bayreuth.de).

ABSTRACT

The geographical and chemical origin of SO^2–₄ deposition has become a concern, because anthropogenic S emissions have influenced the biogeochemistry of forested ecosystems and surface waters. Our aim was to evaluate the origin of SO^2–₄ in bulk precipitation at the Hubbard Brook Experimental Forest (HBEF), New Hampshire. We analyzed 26 years of archived bulk precipitation samples for sulfur stable isotopes. We compared the ³⁴S values with anthropogenic SO₂ emissions, the relative contribution of sea salt aerosols (as the SO^–₄/Na⁺ ratio in precipitation), and temperature and solar radiation effects on the long-term patterns of ³⁴S values. The long-term pattern of ³⁴S values in bulk precipitation could be explained partly by the relative contribution of marine SO^2–₄ or solar radiation but not by temperature variation or anthropogenic SO₂ emissions. The high variability of the ³⁴S values of various fossil fuels makes it difficult to use stable S isotopes for identifying whether changing fossil fuel use is affecting the ³⁴S values in bulk precipitation. The seasonal pattern of ³⁴S values in bulk precipitation (significantly higher values in the winter than the summer) may be explained by the temperature dependence of the isotopic shift during SO^2–₄ formation in the atmosphere. A greater relative contribution of marine SO^2–₄ during the winter also may have contributed to the higher ³⁴S values in the winter. Previous investigations may have overestimated the role of biogenic emissions in affecting the ³⁴S pattern.

This article has been cited by other articles:

				F. J. Zhao, J. S. Knights, Z. Y. Hu, and S. P. McGrath Stable Sulfur Isotope Ratio Indicates Long-Term Changes in Sulfur Deposition in the Broadbalk Experiment since 1845 J. Environ. Qual., January 1, 2003; 32(1): 33 - 39. [Abstract] [Full Text] [PDF]