1 research outputs found
Spatial Dependence of Reduced Sulfur in Everglades Dissolved Organic Matter Controlled by Sulfate Enrichment
Sulfate inputs to the Florida Everglades
stimulate sulfidic conditions
in freshwater wetland sediments that affect ecological and biogeochemical
processes. An unexplored implication of sulfate enrichment is alteration
of the content and speciation of sulfur in dissolved organic matter
(DOM), which influences the reactivity of DOM with trace metals. Here,
we describe the vertical and lateral spatial dependence of sulfur
chemistry in the hydrophobic organic acid fraction of DOM from unimpacted
and sulfate-impacted Everglades wetlands using X-ray absorption spectroscopy
and ultrahigh-resolution mass spectrometry. Spatial variation in DOM
sulfur content and speciation reflects the degree of sulfate enrichment
and resulting sulfide concentrations in sediment pore waters. Sulfur
is incorporated into DOM predominantly as highly reduced species in
sulfidic pore waters. Sulfur-enriched DOM in sediment pore waters
exchanges with overlying surface waters and the sulfur likely undergoes
oxidative transformations in the water column. Across all wetland
sites and depths, the total sulfur content of DOM correlated with
the relative abundance of highly reduced sulfur functionality. The
results identify sulfate input as a primary determinant on DOM sulfur
chemistry to be considered in the context of wetland restoration and
sulfur and trace metal cycling