Insights into Sources and Oxidation Pathways of Nitrate and Sulfate in Whangarei, New Zealand

Abstract:

Because nitrate (NO₃) and sulfate (SO₄) play important roles in climate change, the hydrologic cycle, and human health, understanding their sources and oxidation pathways is crucial. Identifying particulate matter (PM) sources is important for gauging air quality, identifying issues, and creating mitigation strategies; whereas the use of stable oxygen isotopes allows for the assessment of different oxidation pathways. PM collected in Whangarei, New Zealand, was analyzed for elemental, ion, and isotope concentrations to uncover seasonal variations in both source and oxidation pathways used. Because of its location, PM collected in Whangarei was found to be a mixture of anthropogenic (motor vehicles, industry, local biomass burning, shipping) and natural sources (sea salt, DMS), with the majority of samples showing some enrichment in the heavier oxygen isotopes, suggesting ozone oxidation.