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

Abstract

To inform future monitoring and assessment of chemicals of emerging concern (CECs) in coastal urban watersheds, the occurrence and fate of more than 60 pharmaceuticals and personal care products (PPCPs), commercial/household chemicals, current-use pesticides, and hormones were characterized in 2 effluent-dominated rivers in southern California (USA). Water samples were collected during 2 low-flow events at locations above and below the discharge points of water reclamation plants (WRPs) and analyzed using gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry. Approximately 50% of targeted CECs were detectable at stations downstream from WRPs, compared with <31% and <10% at the reference stations above the WRPs. Concentrations of 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) of 3400 ng/L and 2400 ng/L for the 2 rivers. Maximum in-stream concentrations of pyrethroids (bifenthrin and permethrin), diclofenac, and galaxolide exceeded risk-based thresholds established for monitoring of CECs in effluent-dominated receiving waters. In contrast, maximum concentrations of PPCPs commonly detected in treated wastewater (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 WRP discharge until dilution by seawater occurred in the tidal zone, partly because of the short hydraulic residence times in these highly channelized systems (<3 d). In addition to confirming CECs for future in-stream monitoring, these results suggest that conservative mass transport is an important boundary condition for assessment of the input, fate, and effects of CECs in estuaries at the bottom of these watersheds.

Multimedia screening of contaminants of emerging concern (CECS) in coastal urban watersheds in southern California (USA)

“…Maximum aqueous concentrations of TCPP, TDCPP, and TCEP for the Santa Clara River watershed were similar to those reported previously in 2 different effluent‐dominated waterways in southern California , indicating similar discharge loading (i.e., loading from the water reclamation plants) for all 3 effluent‐dominated watersheds in the present study region. In contrast, the maximum Santa Clara River concentration for sucralose was 10‐fold higher than was found in other regional watersheds, suggesting that this compound had a correspondingly higher loading into the upper Santa Clara River water reclamation plants relative to the other watersheds .…”

“…Maximum aqueous concentrations of TCPP, TDCPP, and TCEP for the Santa Clara River watershed were similar to those reported previously in 2 different effluent‐dominated waterways in southern California , indicating similar discharge loading (i.e., loading from the water reclamation plants) for all 3 effluent‐dominated watersheds in the present study region. In contrast, the maximum Santa Clara River concentration for sucralose was 10‐fold higher than was found in other regional watersheds, suggesting that this compound had a correspondingly higher loading into the upper Santa Clara River water reclamation plants relative to the other watersheds . Maximum sediment concentrations of triclocarban in the present study were several fold higher than was reported in Puget Sound (WA, USA; maximum of 17 ng/g dry wt) , but consistent with surface sediment concentrations reported in the vicinity of the marine outfall for a large municipal wastewater treatment plant discharging to the coastal ocean near Los Angeles .…”

New insights into the transformation of trimethoprim during biological wastewater treatment

“…Most wastewater treatment plants (WWTPs) are primarily designed to remove nutrients and easily degradable carbon compounds. It has been shown that they have limited capacities to remove pharmaceuticals (Joss et al., 2006), making them major sources of these micropollutants in rivers and streams (Metcalfe et al., 2010, Sengupta et al., 2014). Certain pharmaceuticals, such as antibiotics, are of particular concern since emission may foster the development of resistant pathogens discharged into the aquatic environment (Marti et al., 2014).…”

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules, metabolism, fate, and transport

“…In the attempt to identify the main sources of contamination by this insecticide, surveys in North Carolina found that fipronil was present in almost all samples, and concentrations were substantially elevated (10-500 ng/L) near wastewater treatment plant drain pipes (McMahen et al 2016). In Californian watersheds, residues of fipronil and its derivatives in surface water are typically in the range 2-13.8 ng/L (Sengupta et al 2014). A survey of the Santa Clara River (California) found maximum concentrations of pyrethroids (bifenthrin and permethrin), polybrominated diphenyl ethers (PBDEs), and derivatives of fipronil in sediment (from LOQ to 6.8 ppb) that exceeded the threshold levels established for freshwater and estuarine sediments in California, which for fipronil are established as 0.09 and 6.5 ppb dry weight, respectively (Maruya et al 2016).…”