Long-term Trends of Volatile Organic Compounds over the Texas, USA in the Past Two Decades

Ruizhe Liu,J.T Anderson

doi:10.1051/e3sconf/202125901003

Abstract

Volatile organic compounds (VOCs) are organic compounds in the air that have low vapor pressure. VOCs can be emitted from a variety of sources including biogenic, anthropogenic and pyrogenic processes. VOCs are precursors of aerosols and tropospheric 03. which harm human health. However, the potential of VOCs forming secondary air pollutants varies by species. Here, we analyze the long-term trends of soiu'ce. concentration and reactivity of six classes of VOCs from 1995 to 2018 over Texas. USA. VOCs emission from petroleum and related companies in Texas kept increasing these years. Among the VOCs tracers of oil and gas companies, the concentration of ethane kept increasing until 2015. Despite the increase of oil and gas related VOCs. the concentration of total VOCs and reactivity-weighted VOCs have decreased in the past two decades. We further investigate the seasonality of VOC reactivities, which depend on both temperature and VOC concentration. We find that VOC reactivity generally is highest in fall and lowest in spring, and such seasonality does not change over the two decades.

Highlights

Volatile organic compounds (VOCs) refer to those that can evaporate under normal temperature and pressure, or indoor atmospheric conditions[1]
To make further analysis of season trends of properties of VOCR, the trends of kT, VOCR, temperature, and arithmetic mean of each class have been shown. (Fig. 5) There are three kinds of trends of VOCR in a seasonal cycle: the values of VOCR of C1C2 aldehydes and biogenic volatile organic compounds (VOCs) were greater in a warmer temperature, the VOCR of temperaturedependent alkane and alkene were greater in a cold environment and VOCR of other types would not change with temperature
We find distinct seasonal cycle of VOC concentration and VOC reactivity in Texas

Summary

Introduction

Volatile organic compounds (VOCs) refer to those that can evaporate under normal temperature and pressure, or indoor atmospheric conditions[1]. As for humans, even breathing low levels of VOCs may lead to increase people’s risk of health problems such as eye, nose and throat irritation, headaches, nausea, and even cancer. Other than water-soluble chemicals, volatile chemicals can be inhaled and absorbed through the skin because of vaporization, displaying a higher possibility of health effects[3]. [2] Inhalation of trimethyl benzenes, xy-lenes, benzene, and alkanes can cause unconsciousness at higher exposures. VOCs cause formation of surface ozone a major air pollutant harmful to human health. VOCs produce tropospheric ozone through photochemical reactions with the reactive hydroxyl radical(OH). Hourly average concentrations of tropospheric ozone can be about 150 ppbv after solar noon.[7]

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Conclusion