Sulfur during early diagenesis in Sphagnum peat: Insights from δ₃₄S ratio profiles in ₂₁Pb‐dated peat cores

Abstract

210Pb chronologies and depth profiles of stable S isotope ratios (834S) and concentrations of organic and inorganic S fractions were determined in peat cores from nine sites in the U.S. and the Czech Republic. Results indicate that depth profiles in S concentrations, S accumulation, and 634S ratios in peat deposits are affected not only by historical patterns in atmospheric S deposition but also by ongoing depthdependent changes in S reduction-oxidation and S immobilization-mineralization processes within a peat deposit. These processes impart a certain degree of mobility to S in peat, bringing into question the validity of reconstructing historical records of S accumulation using dated peat profiles. Over long-term diagenesis, isotopically light S may be continually released from deep peat. This release may result in redistribution of S and S isotopes in peat and suggests that short-term patterns in S accumulation may not persist over much longer time scales.

Isotope composition of bulk carbon in replicated Sphagnum peat cores from three Central European high-elevation wetlands

“…While fossil-fuel burning may contribute to changing δ 13 C in young peat cores, we note that both in aerated forest soils and wetland soils, the common positive downcore δ 13 C shift is almost always accompanied by a positive downcore shift in δ 15 N (Nadelhoffer and Fry, 1988; more than 20 sites in the US) and δ 34 S (Novak et al, 1994; nine sites in the US and Europe). There is no evidence to suggest that atmospheric species of reactive nitrogen and reactive sulfur have been changing toward lower δ 15 N and δ 34 S values due to fossil fuel burning, or any other recent anthropogenic activity.…”

Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle

“…In many modern peats, rainwater is often cited as a major source of sulfate to the plants forming the peat (e.g., refs. 21,25,31). This view, however, is heavily biased by the large fluxes of anthropogenic sulfur to the atmosphere from multiple vectors including biomass burning and fossil fuel combustion.…”

“…The mix of these variable sources will depend on the proximity of the peats to groundwater flow, to riverine input, and on the amounts of sulfate delivered by rain, all of which will change from peat to peat (e.g., refs. 20,25,31). In many modern peats, rainwater is often cited as a major source of sulfate to the plants forming the peat (e.g., refs.…”

Stable isotope studies of moss sulfur and sulfate from bog surface waters

“…The uptake of sulfur during moss growth has been recorded as occurring with a low fractionation (Krouse, 1977;Krouse et al, 1991;Nrigau and Glooschenko, 1992;Novak et al, 1994). The stable isotopic fractionation of sulfur in plants (plant-source) ranges from -8 to 1‰, with an average of -1.5‰ (Trust and Fry, 1992).…”