The occurrence and fate of chemicals of emerging concern in coastal urban rivers receiving discharge of treated municipal wastewater effluent

ySouthern California Coastal Water Research Project Authority, Costa Mesa, California, USAzCalifornia Regional Water Quality Control Board, Los Angeles Region, Los Angeles, California, USAxAdvanced Water Technology Center, Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USAkChemical and Environmental Engineering, University of Arizona, Tucson, Arizona, USA#Los Angeles County Sanitation Districts, Whittier, California, USA(Submitted 2 July 2013; Returned for Revision 15 August 2013; Accepted 2 November 2013)Abstract: To inform future monitoring and assessment of chemicals of emerging concern (CECs) in coastal urban watersheds, theoccurrence and fate of more than 60 pharmaceuticals and personal care products (PPCPs), commercial/household chemicals, current-usepesticides, and hormones were characterized in 2 effluent-dominated rivers in southern California (USA). Water samples were collectedduring 2 low-flow events at locations above and below the discharge points of water reclamation plants (WRPs) and analyzed using gaschromatography–massspectrometryandliquidchromatography–tandemmassspectrometry.Approximately50%oftargetedCECsweredetectableatstationsdownstreamfromWRPs,comparedwith<31%and<10%atthereferencestationsabovetheWRPs.Concentrationsof chlorinated phosphate flame retardants were highest among the CECs tested, with mean total aggregate concentrations of tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) of3400ng/Land2400ng/L forthe 2rivers. Maximum in-stream concentrationsof pyrethroids (bifenthrin andpermethrin), diclofenac, andgalaxolide exceeded risk-based thresholds established for monitoring of CECs in effluent-dominated receiving waters. In contrast,maximumconcentrationsofPPCPscommonlydetectedintreatedwastewater(e.g.,acetaminophen,N,N,diethyl-meta-toluamide[DEET],and gemfibrozil) were less than 10% of established thresholds. Attenuation of target CECs was not observed downstream of WRPdischarge until dilution by seawater occurred in the tidal zone, partly because of the short hydraulic residence times in these highlychannelizedsystems(<3d).InadditiontoconfirmingCECsforfuturein-streammonitoring,theseresultssuggestthatconservativemasstransport is an important boundary condition for assessment of the input, fate, and effects of CECs in estuaries at the bottom of thesewatersheds. Environ Toxicol Chem 2014;33:350–358. # 2013 SETACKeywords: Chemicals of emerging concern (CECs) Pharmaceuticals and personal care products (PPCPs) Occurrence FateUrbanized coastal watersheds Water reclamation plantsINTRODUCTION