Evaluating emerging organic contaminant removal in an engineered hyporheic zone using high resolution mass spectrometry. (1st March 2019)

• Record Type: Journal Article
• Authors: Peter, Katherine T.; Herzog, Skuyler; Tian, Zhenyu; Wu, Christopher; McCray, John E.; Lynch, Katherine; Kolodziej, Edward P.
• Is Part Of: Water research. Volume 150(2019)
• Page Start: 140
• Page End: 152
• Publication Date: 2019-03-01
• Subjects: Non-target analysis -- Suspect screening -- Urban stream restoration -- Stormwater treatment -- Hyporheic zone -- Sorption; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2018.11.050
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: The hyporheic zone (HZ), located at the interface of surface and groundwater, is a natural bioreactor for attenuation of chemical contaminants. Engineered HZs can be incorporated into stream restoration projects to enhance hyporheic exchange, with flowpaths optimized to promote biological habitat, water quantity, and water quality improvements. Designing HZs for in-stream treatment of stormwater, a significant source of flow and contaminant loads to urban creeks, requires assessment of both the hydrology and biogeochemical capacity for water quality improvement. Here, we applied tracer tests and high resolution mass spectrometry (HRMS) to characterize an engineered hyporheic zone unit process, called a hyporheic design element (HDE), in the Thornton Creek Watershed in Seattle, WA. Dye, NaCl, and bromide were used to hydrologically link downwelling and upwelling zones and estimate the hydraulic retention time (HRT) of hyporheic flowpaths. We then compared water quality improvements across hydrologically-linked surface and hyporheic flowpaths (3–5 m length; ∼30 min to >3 h) during baseflow and stormflow conditions. We evaluated fate outcomes for 83 identified contaminants during stormflow, including those correlated with an urban runoff mortality syndrome in coho salmon. Non-target HRMS analysis was used to assess holistic water quality improvements and evaluate attenuation mechanisms. The data indicated substantial water quality improvement in hyporheic flowpaths relative to surface flow and improved contaminant removal with longer hyporheic HRT (for ∼1900 non-target compounds detected during stormflow, <17% were attenuated >50% via surface flow vs. 59% and 78% via short and long hyporheic residence times, respectively), and strong contributions of hydrophobic sorption towards observed contaminant attenuation. Graphical abstract: Highlights: Engineered hyporheic zones (HZs) can treat non-point source pollution in-stream. Hydraulically linked hyporheic flowpaths were identified with non-reactive tracers. Hyporheic flow attenuates many organic contaminants detected in urban runoff. Longer residence times in the HZ promote removal, particularly of polar compounds. Non-target HRMS data can estimate hydrophobicity to evaluate sorption potential.