Wetland Plant Species Responses to Sulfate-Mediated Phosphate Mobilization and Sulfide Toxicity in Contrasting Wetland TypesEPA Grant Number: F6F11279
Title: Wetland Plant Species Responses to Sulfate-Mediated Phosphate Mobilization and Sulfide Toxicity in Contrasting Wetland Types
Investigators: Simkin, Samuel M.
Institution: Cornell University
EPA Project Officer: Hahn, Intaek
Project Period: August 24, 2006 through August 23, 2009
Project Amount: $111,172
RFA: STAR Graduate Fellowships (2006) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Terrestrial Systems Ecology
The objective of this research is to understand how wetland plants growing in contrasting wetland types respond to the indirect impacts of sulfur and nitrogen additions from atmospheric deposition and water pollution. More specifically, contrasts in hydrologic regime, carbon content, and iron chemistry among different wetland types will be used to predict phosphorus availability and hydrogen sulfide toxicity to wetland plants that are exposed to a gradient of sulfur and nitrogen inputs.
I will establish wetland field sites in bogs, fens, and marshes with contrasting ground water inputs of sulfur and iron. Using all sites I will determine the relationships among the pools of sulfur, iron, and phosphorus that are sensitive to soil reduction-oxidation reactions. At a subset of sites I will test the correlative relationships with experimental additions of sulfate and nitrate. The key response variables will be 1) pore water concentrations and solid-phase soil content of sulfur, nitrogen, iron, and phosphorus species, 2) plant tissue concentrations of sulfur, nitrogen, and phosphorus, and 3) plant biomass.
I expect that wetland sulfur supply will influence wetland plant phosphorus nutrition and hydrogen sulfide toxicity. In wetlands with a low supply of reduced iron, I expect that plants will show evidence of past or present hydrogen sulfide toxicity in response to sulfur enrichment and subsequent sulfate reduction. In wetlands with a large supply of reduced iron, I expect that sulfate reduction will be followed by iron sulfide precipitation, phosphate mobilization and subsequent increases in the performance of phosphorus demanding species. Where there are very large inputs of nitrogen or limited carbon, denitrifying bacteria may a)outcompete sulfate reducing bacteria for carbon or b)reoxidize reduced sulfur compounds. In summary, this study will describe current impacts of sulfur and nitrogen loading on wetland plants, and help predict which wetland types are most susceptible to future alterations of sulfur and nitrogen inputs.