Long-term analysis of PM2.5 elemental composition and source contributions in coastal urban environments of Corpus Christi and Houston in Texas

Long-term assessments of fine particulate matter play a key role in identifying persistent and emerging emission contributors. Coastal urban areas are highly susceptible to transboundary dust and wildfire events in addition to local pollution sources. Multi-decadal assessments in these regions using chemical speciation data could offer insights into major pollutant sources and their trends. This study utilizes nearly two decades of PM 2.5 elemental composition data at two major coastal cities in Texas: Houston and Corpus Christi. Fourteen trace elements were analyzed to characterize the seasonal variability and long-term source evolution using a combination of Spearman’s correlation analysis, principal component analysis, enrichment factor analysis and V/Ni diagnostic ratios. Seasonal analysis revealed summertime enhancements in crustal elements in both cities, affected by Saharan dust storms from Africa. Principal component analysis identified crustal dust as the dominant factor across all time periods, while marine aerosol and mixed urban sources were amongst the other factors identified. Heavy fuel oil combustion associated elements such as vanadium and nickel were prominent during early study period but exhibited a marked decline with decreasing enrichment factor values and V/Ni ratios below 2.5. Overall, this long-term analysis demonstrates that PM 2.5 composition in coastal Texas cities is impacted by both local and transboundary natural processes as well as evolving anthropogenic activities. These findings also underscore the importance of speciation monitoring for evaluating regulatory impacts and suggesting mitigation strategies.