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Accumulation of atmospheric sulfur in some Costa Rican soils

Journal of Geophysical Research: Biogeosciences

By:
and
DOI: 10.1029/2008JG000692

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Abstract

Sulfur is one of the macronutrient elements whose sources to terrestrial ecosystems should shift from dominance by rock-weathering to atmospheric deposition as soils and underlying substrate undergo progressive weathering and leaching. However, the nature and timing of this transition is not well known. We investigated sources of sulfur to tropical rain forests growing on basalt-derived soils in the Osa Peninsula region of Costa Rica. Sulfur sources were examined using stable isotope ratios (δ34S) and compared to chemical indices of soil development. The most weathered soils, and the forests they supported, are dominated by atmospheric sulfur, while a less weathered soil type contains both rock-derived and atmospheric sulfur. Patterns of increasing δ34S with increasing soil sulfur concentration across the landscape suggest atmospheric sulfur is accumulating, and little rock-derived sulfur has been retained. Soil sulfur, minus adsorbed sulfate, is correlated with carbon and nitrogen, implying that sulfur accumulation occurs as plants and microbes incorporate sulfur into organic matter. Only the lower depth increments of the more weathered soils contained significant adsorbed sulfate. The evidence suggests a pattern of soil development in which sulfur-bearing minerals in rock, such as sulfides, weather early relative to other minerals, and the released sulfate is leached away. Sulfur added via atmospheric deposition is retained as organic matter accumulates in the soil profile. Adsorbed sulfate accumulates later, driven by changes in soil chemistry and mineralogy. These aspects of sulfur behavior during pedogenesis in this environment may hasten the transition to dominance by atmospheric sources.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Accumulation of atmospheric sulfur in some Costa Rican soils
Series title:
Journal of Geophysical Research: Biogeosciences
DOI:
10.1029/2008JG000692
Volume
113
Issue:
G3
Year Published:
2013
Language:
English
Publisher:
American Geophysical Union
Contributing office(s):
University of Colorado- Boulder
Description:
G03001
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research: Biogeosciences
Country:
Costa Rica