biogeochemistry of sulfur
stable sulfur isotopes
Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Abstract In natural ecosystems, differences often exist in the relative abundanceof stable S isotopes (°34S) that can provide clues as tothe source, nature, and cycling of S. Values of °34S inprecipitation, throughfall, soils, soil solution, and stream waters weremeasured at the Hubbard Brook Experimental Forest (HBEF), New Hampshire.Values of °34S in precipitation and throughfall weresimilar to each other but differed seasonally. Precipitation°34S values were higher in the dormant season[°34S = 5.9±0.6‰ (17)][Mean + SE(N)]than in the growing season [°34S = 5.0±0.6‰(40)] but throughfall growing-season values were higher[°34S = 5.6±0.6‰(68)] than for the dormantseason [°34S = 4.9±0.7‰ (9)]. Different treespecies did not affect throughfall °34S values. In soilsolution, °34S values were higher in the growing season(°34S = 8.9±2.8‰; 8.8±1.7‰;and 4.0±0.6‰ for Oa, Bh, and Bs horizons, respectively) thanin the dormant season (°34S = 5.6±1.5‰;3.7±2.4‰; and 3.4±1.2‰ for Oa, Bh, and Bshorizons, respectively). These seasonal differences in°34S were probably caused by biological isotopicfractionation. The °34S values in streams were generally2‰ lower and more variable than those in precipitation andthroughfall, suggesting fractionation and/or different isotopic sources inthe soil.
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