Distribution of Halogenated Volatile Organic Compounds (VOCs) in Galveston Bay, TX

Many halogenated volatile organic compounds (VOCs), such as carbon tetrachloride, CFC-11, and CFC-12, are banned by the Montreal Protocol due to their destructive effect on the stratospheric ozone layer. Recent studies show the continued emission of some of these halogenated VOCs in regions around the globe, including in the Houston area. Galveston Bay is profoundly affected by the industry and chemical plants of Houston through their discharges into the freshwater inputs for the bay, including the San Jacinto River, Trinity River, Dickinson Bayou and Buffalo Bayou. Little information is available on the water concentrations of these halogenated VOCs in either the bay or its freshwater sources. Analysis of samples collected in March and June 2019 from nine sites in Galveston Bay and in June 2019 from two to three sites in each of the major freshwater sources helps elucidate the spatial distribution of a suite of halogenated VOCs in and entering Galveston Bay.

The Deer Park Intercontinental Terminals Company (ITC) fire began March 17, 2019, was ultimately extinguished on March 20. However, there was a breach in the wall surrounding the tanks on March 22 that released chemicals into the Houston Shipping Channel, lower San Jacinto River. Samples from March 23, 2019, demonstrated higher than expected concentrations of halogenated VOCs in Galveston Bay, TX, with noticeably elevated concentrations in the lower San Jacinto River as compared to other areas of the bay. The abundance of these halogenated VOCs decreased over time in the bay following the ITC fire, yet elevated concentrations remain in the major freshwater sources, leading to elevated fluxes of halogenated VOCs into the bay. Continued monitoring of the freshwater sources into Galveston Bay, along with Galveston Bay itself, is necessary to understand whether the elevated concentrations are directly related to the ITC fire.