|Abstract Title:||Characterizing mercury complexation with dissolved organic matter from Everglades periphyton using chelating resin-based ion-exchange method|
|Presenter Name:||Afia Anjuman|
|Company/Institution:||Florida International University/ Department of Chemistry and Biochemistry|
|Session:||Mercury in Freshwater Ecosystems|
Abstract Information :
Dissolved organic matter (DOM) plays a central role in controlling mercury (Hg) speciation and subsequent transformation as Hg has a high affinity toward DOM complexation because of the presence of various functional groups in DOM, especially thiol (-SH) group. The Florida Everglades is consumed by elevated levels of methyl mercury (CH3Hg+) in fish and wildlife, where Hg methylation and cycling are regulated by DOM originated from various sources such as terrestrial plants, algae, and bacteria. As the major producer, periphyton is a unique feature of the Everglades ecosystem and can be an important source of DOM. This study was aimed to investigate Hg complexation with the freshly released DOM from periphyton in the Everglades, represented by the DOM present in periphyton pore water (PPW). An ion exchange method based on a chelating resin with thiol group for competitive Hg binding was used to determine the distribution of Hg between the resin and DOM. Cold Vapor Atomic Fluorescence Spectroscopy (CV-AFS) was used to measure the concentrations of total Hg (THg) after the reactions reached equilibrium. The conditional stability constant and distribution coefficient of Hg complexes with DOM were estimated from the THg analysis. The distribution coefficient decreased in the presence of PPW DOM (1.07??10?^3 ml/g) than surface water (SW) DOM (9.11??10?^3 ml/g), indicating higher Hg-complexing capability of PPW DOM and corresponding to higher conditional stability constants of Hg-PPW DOM complexes.