Influence of root Fe plaque on phosphorus cycling in a Great Lakes coastal wetland

Session: Poster Session

Megan Smith, Kent State Univeristy, [email protected]
Lauren Kinsman-Costello, Kent State University, [email protected]

Abstract

Old Woman Creek estuary, a Lake Erie coastal wetland, acted as an effective nutrient sink between October 1989 and September 1990. Yet, nutrient retention mechanisms are not fully-understood and mass balance studies are an unfeasible approach for predicting nutrient retention rates. Phosphorus sorbs to Fe(III) in oxidized sediments. However, continuously-inundated sediments lead to reduced conditions, where phosphate ions are released when Fe(III) dissolves to Fe(II). Radial oxygen loss occurs from hydrophyte roots as a by-product of the transport of oxygen for respiration, introducing oxygen into reduced sediments. As a result, Fe(II) in surrounding sediments is oxidized to Fe(III) oxides, which accumulate on roots to form iron plaques to which phosphorus may be sorbed. This project aims to characterize how plant community influences phosphorus cycling in wetland sediments as a function of iron plaque formation and redox regime in Old Woman Creek estuary. The following relationships are predicted on two-scales: (1) phosphorus retention in the root zone will increase with iron plaque formation on roots and (2) sample sites dominated by rhizomatous plants will contain more iron-bound phosphorus than open water sites. Preliminary data will be shared to discuss 2018 redox regime and phosphorus cycling across patch scales.