Utilizing High Resolution Mass Spectrometry for Improved Characterization of CECs Occurrence and Impacts in Puget Sound watershed.

There is limited information on the occurrence and impacts of Contaminants of Emerging Concern (CECs) in the Puget Sound watershed. Previous targeted monitoring demonstrated that CECs are widespread and some may occur at levels of environmental concern. However, targeted methods focus only on a predefined suite of contaminants and likely under-represent actual contaminant profiles. Recent developments in high resolution mass spectrometry (HRMS) and data analysis allow suspect and non-target screening of pollutants in complex environmental samples which greatly expand the potential for characterization. We established and optimized workflows for suspect and non-target screening, and applied these to marine water, creek water, and mussel tissue samples collected from throughout the Puget Sound watershed. Marine water samples were collected from 18 locations. Over 87 unique CECs were identified, many of which had not been previously reported. Low levels of methamphetamine were detected in 41% of the samples, and perfluorooctanesulfonic acid (PFOS) concentrations were as high as 70-140 ng/L at one site. Transformation products of pesticides were identified, including two novel transformation products of tebuthiuron. Risk quotients were calculated based on concentrations and predicted toxicities, and eight CECs had risk quotients \u3e1. Source analysis indicated that wastewater effluent influenced much of the marine nearshore environment, and that there were additional localized contributions from stormwater and industrial sources. For the mussel samples, we applied three extraction methods, and compared their performance and coverage on different contaminant groups. We collected creek water samples during rain events from five sites. Creek water from urban/industrial sites featured profiles consistent with traffic and wastewater influence, rural sites reflected the impact of agriculture with a variety of pesticides and their transformation products. These findings highlight the necessity of suspect and non-target screening, and reveal the impact of different contamination sources in aquatic environments