Elevated nighttime isoprene concentrations in the Houston shipping channel : short-range transport dynamics of localized industrial emissions.

Volatile organic compounds (VOCs) were measured in the Houston, Texas Shipping Channel during the Tracking Aerosol Convection Interactions Experiment Air Quality 1 (TRACER-AQ1) field campaign using a Proton Transfer Reaction – Mass Spectrometer (PTR-MS). The Houston Shipping Channel has many industrial facilities and is routinely used for maritime trade. Industries that manufacture rubbers, polymers, and adhesives have recently been using isoprene, a biogenic VOC, in their manufacturing processes. As of 2021, there are 3,552 reported isoprene point sources in Harris County alone. During the TRACER-AQ1 campaign, concentrations of isoprene were observed at higher values than what was biogenically available on nights such as September 17, 2021. By using a threshold value of one standard deviation above the average campaign concentration, exceedances were determined by observing and recording data that exceeded this threshold. The National Oceanic and Atmospheric Administration’s Real-time Environmental Applications and Display sYstem Hybrid Single-Particle Lagrangian Integrated Trajectory dispersion model was employed to model the atmospheric transport of the plumes formed by the anthropogenic sources of isoprene and its oxidation products.