Using Performance Reference Compound-Corrected Polyethylene
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Chemosphere 127 (2015) 10–17 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere Using performance reference compound-corrected polyethylene passive samplers and caged bivalves to measure hydrophobic contaminants of concern in urban coastal seawaters ⇑ Abigail S. Joyce a,1, Mallory S. Pirogovsky a, Rachel G. Adams b, , Wenjian Lao c, David Tsukada c, Curtis L. Cash d, James F. Haw a, Keith A. Maruya c a University of Southern California, Los Angeles, CA, United States b Loyola Marymount University, Los Angeles, CA, United States c Southern California Coastal Water Research Project Authority, Costa Mesa, CA, United States d City of Los Angeles Environmental Monitoring Division, Playa del Rey, CA, United States highlights Hydrophobic organic contaminants were measured with polyethylene passive samplers. Seawater concentrations measured up to 1000 pg LÀ1 (p,p0-DDE) & 300 pg LÀ1 (DDNU). Seawater measurements with depth suggest bed sediments were a source of DDTs & PCBs. Co-deployed mussel- and polyethylene-measured concentrations correlated strongly. article info abstract Article history: Low-density polyethylene (PE) passive samplers containing performance reference compounds (PRCs) Received 8 September 2014 were deployed at multiple depths in two urban coastal marine locations to estimate dissolved concentra- Received in revised form 17 December 2014 tions of hydrophobic organic contaminants (HOCs), including dichlorodiphenyltrichloroethane (DDT) and Accepted 19 December 2014 its metabolites, polychlorinated biphenyl (PCB) congeners, and polybrominated flame retardants. PE sam- plers pre-loaded with PRCs were deployed at the surface, mid-column, and near bottom at sites repre- Handling Editor: Caroline Gaus senting the nearshore continental shelf off southern California (Santa Monica Bay, USA) and a mega commercial port (Los Angeles Harbor). After correcting for fractional equilibration using PRCs, concentra- À1 À1 Keywords: tions ranged up to 100 pg L for PCBs and polybrominated diphenyl ethers (PBDEs), 500 pg L for À1 À1 0 Passive samplers DDMU and 300 pg L for DDNU, and to 1000 pg L for p,p -DDE. Seawater concentrations of DDTs Seawater and PCBs increased with depth, suggesting that bed sediments serve as the source of water column HOCs Bivalves in Santa Monica Bay. In contrast, no discernable pattern between surface and near-bottom concentrations PCBs in Los Angeles Harbor was observed, which were also several-fold lower (DDTs: 45–300 pg LÀ1, PCBs: 5– DDTs 50 pg LÀ1) than those in Santa Monica Bay (DDTs: 2–1100 pg LÀ1, PCBs: 2–250 pg LÀ1). Accumulation by PBDEs mussels co-deployed with the PE samplers at select sites was strongly correlated with PE-estimated sea- water concentrations, providing further evidence that these samplers are a viable alternative for monitor- ing of HOC exposure. Fractional equilibration observed with the PRCs increased with decreasing PRC molar volume indicating the importance of target compound physicochemical properties when estimat- ing water column concentrations using passive samplers in situ. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction The southern California coastal zone is a densely populated, ⇑ Corresponding author. Tel.: +1 310 338 5186. highly urbanized and industrialized region where the input and E-mail address: [email protected] (R.G. Adams). fate of hydrophobic organic contaminants (HOCs) in the nearshore 1 Office of Research and Development, National Health and Environmental Effects ocean environment remains an issue of concern (Schiff, 2000). This Research Laboratory – Atlantic Ecology Division, US Environmental Protection coastal zone receives discharge of treated wastewater effluent and Agency, Narragansett, Rhode Island, United States. http://dx.doi.org/10.1016/j.chemosphere.2014.12.067 0045-6535/Ó 2015 Elsevier Ltd. All rights reserved. A.S. Joyce et al. / Chemosphere 127 (2015) 10–17 11 stormwater runoff from a population base of more than 10 million 2. Theory people. HOCs that have been deposited in bedded sediments continue to be available to biota in this marine ecosystem At equilibrium, the concentration of a HOC dissolved in water, À1 (Fernandez et al., 2012, 2014). Two of the most prevalent contam- CW (pg L ), can be estimated from the mass of the HOC sorbed inants in the Southern California Bight (SCB), a system that by the PE sampler and the chemical-specific PE-water partition À 1 includes Santa Monica Bay and the Palos Verdes Shelf (PVS), are coefficient (KPEW; Lwater kgPE ). CW is calculated under equilibrium remnants of technical DDT and PCB mixtures (Venkatesan et al., conditions: 1996; Eganhouse et al., 2000). In fact, the U.S. Environmental Pro- 1 CPE tection Agency added the PVS to the National Priorities List and is CW ¼ ð1Þ currently evaluating remediation approaches for the site (EPA, KPEW 2009). More recently, brominated flame retardants have received 1 À 1 where CPE (pg kgPE ) is the HOC concentration sorbed by the PE at attention due to their toxic potential in the aquatic environment equilibrium. PRCs can be added to the PE prior to deployment to (Darnerud, 2008). Polybrominated diphenyl ethers (PBDEs) have assess (and if necessary, to correct for) the extent of equilibrium been detected in virtually all ecosystems and taxa (Covaci et al., achieved (Adams et al., 2007). The PRC will allow for equilibrium 2011) and remain a concern in the SCB region and along the Cali- to be assessed under varying ambient conditions (Booij et al., fornia coast (Dodder et al., 2012; Maruya et al., 2014). Because of 2003). The fractional equilibration (f ) achieved by a PRC can be cal- their persistence and toxicity, PBDEs are being phased out of com- culated as (Fernandez et al., 2012; Friedman et al., 2012): mercial use in the United States (EPA, 2009). t Monitoring to ensure that HOC concentrations are not CPRC f ¼ 1 À 0 ð2Þ approaching harmful levels is an essential component of protecting CPRC the integrity of the nearshore ocean environment. In addition, 0 t exposure risks and emission reduction effectiveness can be where CPRC and CPRC represent the concentration of the PRC prior to assessed by measurement of freely dissolved HOC concentrations and after deployment, respectively. Note that this is a first-order, Ct PRC Àket (Lohmann and Muir, 2010). The state of California has set coastal exponential model (Adams et al., 2007)as1À 0 ¼ 1 À e where CPRC ocean water column guidelines for the DDT metabolite dic- k is a first-order exchange rate coefficient. PRCs are matched to À1 e hlorodibenzoethene (DDE) at 590 pg L and for total PCBs at analytes with comparable physiochemical properties (e.g., molar À1 170 pg L (EPA, 2000). However, achieving such low monitoring volume, diffusivity, partitioning coefficient). Equation (3) below is thresholds is difficult and costly with conventional methods, which 1 thus used to estimate C so that CW may be calculated in Eq. (1), in addition, often cannot achieve the desired detection limits PE (Burgess, 2012). Direct measurement of the freely dissolved water Ct C1 ¼ PE ð3Þ concentration has shown promise in estimating the bioavailability PE f of HOCs (Borga et al., 2005). where Ct , is the target analyte concentration after deployment. The Bivalves have been used to monitor water quality in the U.S. PE since 1975 (Farrington et al., 1983; Goldberg and Bertine, 2000). surface area of the PE deployed can be increased in order to allow À1 Because they are sessile and can filter hundreds of liters of seawa- for very low concentrations (e.g., pg L ) to be detected by the large ter every day, bivalves provide time-integrated measurements of sorbing capacity. chemical concentrations in coastal waters (Goldberg and Bertine, If tissue concentration data are available for sentinel organisms 2000; O’Connor and Lauenstein, 2006). Polymer passive samplers exposed to HOCs in seawater (e.g. sessile bivalves), the bioconcen- À1 that concentrate target analytes such as HOCs from the aqueous tration factor (BCF, L kg ) is defined as phase can serve as alternative water quality sentinels (Gorecki Cb and Namiesnic, 2002; Mayer et al., 2003; Zabiegala et al., 2010). BCF ¼ ð4Þ CW The utility of passive samplers is maximized when operated in À1 À1 equilibrium mode; i.e. when the concentrations in the water and where Cb (ng kg ) is the biota tissue concentration and CW (ng L ) passive sampler has reached steady-state; however, when equilib- is defined above (Arnot and Gobas, 2006). rium is not achieved, performance reference compounds (PRCs) may be used to correct for non-equilibrium (Adams et al., 2007; 3. Materials and methods Booij et al., 2002). Low-density polyethylene (PE) has been success- fully used to measure DDT metabolites and PCBs in seawater 3.1. Materials (Fernandez et al., 2012), and shows promise in measuring PBDEs (Sacks and Lohmann, 2012). Low-density PE sheeting (Covalence, Minneapolis, MN; 25 lm Recently, Fernandez et al. (2012, 2014) measured PCBs and DDT thick) was cut into strips (5 cm  100 cm, 2 g) and pre-cleaned metabolites in PVS seawater using PE and SPME passive samplers in dichloromethane (DCM; 1 day) and methanol (MeOH; 3 days) and reported a gradient emanating from bottom sediments and prior to loading PRCs. PRCs were loaded into cleaned PE in 1.8 L also away from a known area of elevated contamination (a marine of a 4:1 MeOH:water spiking solution containing PCB congeners: 13 Superfund site). In this study we used PE passive samplers, pre- 50, 155, and 184 (Ultra Scientific, N. Kingston, RI, USA) and C12- loaded with PRCs, to measure DDT and its metabolites, PCBs, and p,p0-DDE (99%, Cambridge Isotope Laboratories, Inc., Andover, PBDEs in the coastal ocean and a semi-enclosed embayment (Los MA, USA) for 20 days (Booij et al., 2002). The nominal concentra- Angeles Harbor) to allow for a comparison of PRC kinetics over a tion of each PRC in the spiking solution was 100 lgLÀ1.