This award is supported jointly by the Chemistry Division's Environmental Chemical Sciences Program and the Environmental Engineering Program in the Division of Chemical, Bioengineering, Environmental, and Transport Systems. Dr. Michael Gonsior and colleagues at the University of Maryland Center for Environmental Science collaborate with Dr. Susan Richardson at the University of South Carolina. They study the formation of chemical compounds that arise during disinfection of seawater, which is required before water can be used in major desalination plants in the U.S. and Australia. Desalination is an important method for turning salt water into drinkable (potable) water in many parts of the world. It is becoming an increasingly important treatment technology as freshwater supplies are becoming scarcer. However, currently potentially harmful organic compounds produced during disinfection treatments are discharged into the aquatic environment in the waste water stream. The consequences of these organic compounds to aquatic organisms are largely unknown. This study provides new knowledge regarding the formation of previously unknown disinfection by-products (DBPs) produced during desalination. New quantification methods for organic compounds in aqueous environments are also developed. Undergraduate students are exposed to this research through internships, such as through the Maryland Sea Grant REU program and at USC. The CBL Visitor Center host displays about seawater DBPs, how they are formed and what impact they may have on the coastal ocean. In partnership with the Chesapeake Biological Laboratory Visitor Center, the research team hosts a summer workshop for 7-12th grade school students/teachers. The investigators also collaborate with colleagues in the U.S, Australia, and Germany, including industry partners from major desalination plants.
Future reliance on desalination and water reuse to provide suitable drinking water is expected globally. During the desalination process, chlorination of water is required to limit biofouling of membranes and to kill potentially harmful bacteria. The formation of Disinfection Byproducts (DBPs) during drinking water chlorination and the compounding factors presented by different sources of fresh water, such as high levels of dissolved organic matter (DOM), is well recognized. However, during the chlorination of seawater, hundreds of brominated and iodinated compounds are formed, few of which have been characterized, and some of which are already known to be highly toxic. The researchers utilize new analytical techniques to investigate the production, fate and toxicity of DBPs in the coastal environment. Ultrahigh resolution mass spectrometry has been utilized to describe complex organic matrices at the molecular level, and has successfully demonstrated the complexity of DBPS formed after chlorination of ship ballast water as well as characterizing DOM in natural waters. All of these studies have shown that highly precise mass measurements combined with soft ionization are capable of assigning unambiguous and exact molecular formulas. In combination with traditional gas chromatography interfaced with mass spectrometry methods to support quantification of a subset of compounds, the team characterizes DBPs at different steps of the desalination process and evaluates the fate of produced DBPs released into the environment. The students and faculty combine desalination plant measurements with controlled laboratory studies to better understand the mechanisms and factors contributing to the production, fate and the toxicity of known and newly discovered DBPs formed in seawater during pre-chlorination and accumulated in waste waters discharged into coastal ecosystems.
