Measurements of radical precursors at the western edge of the Houston Ship Channel during SHARP 2009

Measurements of formaldehyde (HCHO), peroxyacyl nitrates (PANs) and carbon monoxide (CO) were carried out at Clinton Drive, a TCEQ/City of Houston measurement site located at the western edge of the Houston Ship Channel, during 6 weeks within SHARP 2009 campaign (April-June). Additional measurements were provided by the City of Houston (ozone, VOCs, SO2, NO2, and meteorological parameters) and TCEQ (online VOCs).

Primary goal of this study was the determination of radical precursors sources at different times of the day, under specific environmental conditions, e.g. under the influence of closely located industrial facilities, industrial road and highway. Herein we report the distribution of individual VOCs, formaldehyde, PAN and other species discriminated among day and nighttime conditions as well as under different meteorological regimes. Ratios such as HCHO/CO and HCHO/PAN and others were used to distinguish between primary and secondary sources of formaldehyde. A few events with elevated values of VOCs occurred in late May, which were related to increased mixing ratios of formaldehyde and asscoiated with direct emissions from industrial facilities. VOCs showed distinct patterns depending on the wind direction and indicated specific industrial sources, e.g. petrochemical emissions, sometimes related to specific stacks.