Chemical UV Filters are emerging marine pollutants and are found ubiquitously in the ocean. Octinoxate ((RS)-2-Ethylhexyl (2E)-3-(4-methoxyphenyl)prop-2-enoate), which is used widely in sunscreens and other cosmetic products, has raised concerns because of its toxicity and impact on coral reef environments but remains largely under-regulated. Octinoxate has been observed to be a common anthropogenic pollutant in sea spray aerosol in coastal environments, but there is little understanding of its environmental lifetime and fate in the aerosol phase. Octinoxate is also semi-volatile and has been shown to form stable higher molecular weight cyclodimers in the condensed phase upon irradiation of UV light, potentially contributing to secondary organic aerosol (SOA) mass growth in coastal as well as urban environments. In this work, we employ an irradiated aerosol flow tube reactor coupled to an extractive electrospray ionization high-resolution time-of-flight chemical ionization mass spectrometer (EESI-HR-ToF-CIMS) to determine the chemical lifetime and oxidative transformations of octinoxate in lab-generated aerosol in the presence of UV light, ozone (O3) and the hydroxyl radical (OH). We will report the reactive uptake coefficients (γrxn) of O3 and OH by octinoxate and discuss potential SOA formation pathways and yields following irradiation of octinoxate in the aerosol phase and gas-phase oxidation by OH and O3 in a potential aerosol mass (PAM) reactor. With increasing usage of UV organic filters, such as octinoxate, and their ubiquity in aerosol in coastal environments, it is critical that we examine their degradation kinetics and transformations in the aerosol phase to help inform future risk assessment models.

Heterogeneous oxidative degradation and potential secondary organic aerosol yields of the toxic organic UV filter, octinoxate, by OH, O3, and UV irradiation

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.