HULIS Enhancement of Hydroxyl Radical Formation from Fe(II): Kinetics of Fulvic Acid–Fe(II) Complexes in the Presence of Lung Antioxidants

Published on 2017-06-19T20:44:25Z (GMT) by
Oxidative stress mediated by reactive oxygen species (ROS) is a hypothesized mechanism for particulate-matter related health effects. Fe­(II) is a key player in ROS formation in surrogate lung fluid (SLF) containing antioxidants. Humic-like substances (HULIS) in particulate matter such as biomass burning aerosol chelate Fe­(II), but the effect on ROS formation in the presence of lung antioxidants is not known. We use Suwanee River Fulvic Acid (SRFA) as a surrogate for HULIS and investigate its effect on OH formation from Fe­(II). For the first time, a chemical kinetics model was developed to explain behavior of Fe­(II) and SRFA in SLF. Model and experimental results are used to find best-fit rate coefficients for key reactions. Modeling results indicate SRFA enhances Fe-mediated reduction of O<sub>2</sub> to O<sub>2</sub><sup>–</sup> and destruction of H<sub>2</sub>O<sub>2</sub> to OH to 5.1 ± 1.5 and (4.3 ± 1.4) × 10<sup>3</sup> M<sup>–1</sup> s<sup>–1</sup> respectively. Best-fit rates for Citrate–Fe­(II) mediated O<sub>2</sub> to O<sub>2</sub><sup>–</sup> and H<sub>2</sub>O<sub>2</sub> to OH were 3.0 ± 0.7 and (4.2 ± 1.7) × 10<sup>3</sup> M<sup>–1</sup> s<sup>–1</sup> respectively. The kinetics model agrees with both the experimental results and thermodynamic model calculations of chemical speciation for 0 and 5 μg/mL SRFA, but both models are less successful at predicting further enhancements to OH formation at higher SRFA Concentrations.

Cite this collection

Gonzalez, David

H.; Cala, Christopher K.; Peng, Qiaoyun; Paulson, Suzanne E. (2017): HULIS

Enhancement of Hydroxyl Radical Formation from

Fe(II): Kinetics of Fulvic Acid–Fe(II) Complexes in the Presence

of Lung Antioxidants. ACS Publications.

https://doi.org/10.1021/acs.est.7b01299

Retrieved: 08:57, Nov 24, 2017 (GMT)