Sulfur cycling in salt marshes of Jamaica Bay, Gateway National Recreation Area: Possible links to marsh loss

Cochran, J.; Kolker, Alexander; Hirschberg, David; Renfro, Alisha; Heilbrun, Christina; Goodbred, Steven; Beck, Aaron

The salt marshes within Jamaica Bay display high levels of pore water sulfide, a phytotoxin that can cause toxicity in Spartina sp. The pattern of pore water sulfide in the different marshes is consistent with the pattern of marsh loss, with JoCo (a stable marsh) displaying lower pore water sulfide concentrations (generally <5 mM) than seen at the highly degraded Elders East (up to 19 mM) or Big Egg (up to 8 mM) prior to restoration projects at those sites. There are both seasonal and interannual variations in the pore water sulfide concentrations to which marsh plants are exposed. Values were generally higher in 2004-2006 than 2007 (at sites where interannual comparison was possible), possibly due to temporal variation in organic loading onto the marsh surface. Solid phase sulfur and Fe data complement the perspective gained from the pore water sulfide data. They suggest that JoCo may display lower pore water sulfide because a greater fraction of the pore water sulfide produced by sulfate reduction is associated with solid phase sulfide phases, principally pyrite (FeS2), that precipitate from pore water. In part this reflects the amount of total reactive Fe present in the fine-grained sediment at JoCo. However, JoCo also shows a very high "Degree of Pyritization", indicating that most of the reactive Fe is associated with pyrite and unavailable to react with newly produced pore water sulfide to precipitate fresh pyrite. This may be interpreted as a cautionary sign that JoCo is near the biogeochemical "limit" of its ability to deal with pore water sulfide. In contrast, the restoration effort at Elders East re-set the sediment biogeochemical system to lower degrees of pyritization, providing more flexibility for future biogeochemical regulation of pore water sulfide through iron sulfide precipitation. This study provides circumstantial support for a "sulfur-logging" positive feedback model of marsh loss in Jamaica Bay, however further testing of this model is needed. We recommend 1) establishing reference sites in key marshes (stable, degrading and restored) that can be sampled seasonally for pore water sulfide, nutrients and pH and 2) collection of cores in conjunction with each pore water sampling to be analyzed for solid phase leachable iron, carbon and nitrogen, and sulfur phases

Sulfur cycling in salt marshes of Jamaica Bay, Gateway National Recreation Area: Possible links to marsh loss

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