Air quality degradation is a global concern, particularly in densely populated regions where anthropogenic emissions are concentrated, necessitating measures to safeguard public health. Urban areas face significant challenges from particulate matter (PM) pollutants including detrimental effects on human health and contribution to acid rain and nutrient loading. The first step to mitigating PM emissions is to determine their source origin. This project aims to use isotopic techniques coupled with remote sensing data to apportion the NOx emission sources (i.e., industrial, biomass burning, soil biogenic, vehicles, lightning) contributing PM_2.5 nitrate in a semi-arid coastal urban airshed (Corpus Christi, TX, USA which is nearing PM_2.5 nonattainment of 9.0 μg/m³). This will be complemented using aerosol optical properties coupled with reference clusters to apportion sources of aerosol contributions (i.e., maritime, biomass burning, industrial/urban, dust, mixed). To accomplish this, biweekly PM_2.5 samples will be collected on quartz fiber filters using a URG-3000-ABC medium-volume sampler. Filter eluents will be analyzed for nitrate isotopic composition (δ¹⁵N, δ¹⁸O, δ¹⁷O), and delta values will be employed in Bayesian isotope mixing models to determine emission source apportionment and investigate oxidative pathways. Our group participates in NASA's AERONET network, and the associated Cimel Sun Photometer will provide aerosol optical properties to apportion aerosol types. Results will be disseminated to state environmental agencies and regional air quality groups to aid in creating informed emission mitigation strategies for urban coastal regions.

¹ Department of Physical and Environmental Sciences, Texas A&M University - Corpus Christi, Corpus Christi, TX

² Center for Water Supply Studies, Texas A&M University - Corpus Christi, Corpus Christi, TX

* Corresponding Author: cguidry@islander.tamucc.edu