Bioanalytical and non-targeted mass spectrometric screening for contaminants of emerging concern in Southern California bight sediments

Assessing the impact of chemical contaminants on aquatic ecosystem health remains challenging due to complex exposure scenarios and the myriad of impact metrics to consider. To expand the breadth of compounds monitored and evaluate the potential hazard of environmental mixtures, cell-based bioassays (estrogen receptor alpha (ERα) and aryl hydrocarbon receptor (AhR)) and non-targeted chemical analyses with high resolution mass spectrometry (NTA-HRMS) were used to assess the quality of ∼70 marine sediment samples collected from 5 distinct coastal and offshore habitats of the Southern California Bight. AhR responses (<0.12-4.5 ng TCDD/g dry weight) were more frequently detectable and more variable than for ERα (<0.1-0.5 ng E2/g dry weight). The range of AhR and ERα responses increased by habitat as follows: Channel Islands < Mid-shelf < Marinas < Ports < Estuaries. The narrow range and magnitude of ERα screening response suggested limited potential for estrogenic impacts across sediments from all 5 habitats. The AhR response was positively correlated with total PAH and PCB concentrations and corresponded with a chemical score index representing the severity of metal and organic contamination. NTA-HRMS fingerprints generated in positive electrospray ionization mode were clearly distinguishable among coastal vs. offshore samples, with the greatest chemical complexity (n = 982 features detected) observed in estuarine sediment from a highly urbanized watershed (Los Angeles River). The concordance and complementary nature of bioscreening and NTA-HRMS results indicates their utility as holistic proxies for sediment quality, and when analyzed in conjunction with routine targeted chemical monitoring, show promise in identifying unexpected contaminants and novel toxicants.

Passive-Sampler-Derived PCB and OCP Concentrations in the Waters of the World─First Results from the AQUA-GAPS/MONET Network

Persistent organic pollutants (POPs) are recognized as pollutants of global concern, but so far, information on the trends of legacy POPs in the waters of the world has been missing due to logistical, analytical, and financial reasons. Passive samplers have emerged as an attractive alternative to active water sampling methods as they accumulate POPs, represent time-weighted average concentrations, and can easily be shipped and deployed. As part of the AQUA-GAPS/MONET, passive samplers were deployed at 40 globally distributed sites between 2016 and 2020, for a total of 21 freshwater and 40 marine deployments. Results from silicone passive samplers showed α-hexachlorocyclohexane (HCH) and γ-HCH displaying the greatest concentrations in the northern latitudes/Arctic Ocean, in stark contrast to the more persistent penta (PeCB)- and hexachlorobenzene (HCB), which approached equilibrium across sampling sites. Geospatial patterns of polychlorinated biphenyl (PCB) aqueous concentrations closely matched original estimates of production and use, implying limited global transport. Positive correlations between log-transformed concentrations of Σ₇PCB, ΣDDTs, Σendosulfan, and Σchlordane, but not ΣHCH, and the log of population density (p < 0.05) within 5 and 10 km of the sampling sites also supported limited transport from used sites. These results help to understand the extent of global distribution, and eventually time-trends, of organic pollutants in aquatic systems, such as across freshwaters and oceans. Future deployments will aim to establish time-trends at selected sites while adding to the geographical coverage.

Bioanalytical and chemical-specific screening of contaminants of concern in three California (USA) watersheds

To broaden the scope of contaminants monitored in human-impacted riverine systems, water, sediment, and treated wastewater effluent were analyzed using receptor-based cell assays that provide an integrated response to chemicals based on their mode of biological activity. Samples were collected from three California (USA) watersheds with varying degrees of urbanization and discharge from municipal wastewater treatment plants (WWTPs). To complement cell assay results, samples were also analyzed for a suite of contaminants of emerging concern (CECs) using gas and liquid chromatography-mass spectrometry (GC- and LC-MS/MS). For most water and sediment samples, bioassay equivalent concentrations for estrogen and glucocorticoid receptor assays (ER- and GR-BEQs, respectively) were near or below reporting limits. Measured CEC concentrations compared to monitoring trigger values established by a science advisory panel indicated minimal to moderate concern in water but suggested that select pesticides (pyrethroids and fipronil) had accumulated to levels of greater concern in river sediments. Integrating robust, standardized bioanalytical tools such as the ER and GR assays utilized in this study into existing chemical-specific monitoring and assessment efforts will enhance future CEC monitoring efforts in impacted riverine systems and coastal watersheds.

Transcriptomic response patterns of hornyhead turbot (Pleuronichthys verticalis) dosed with polychlorinated biphenyls and polybrominated diphenyl ethers

To evaluate the impact of environmental contaminants on aquatic health, extensive surveys of fish populations have been conducted using bioaccumulation as an indicator of impairment. While these studies have reported mixtures of chemicals in fish tissues, the relationship between specific contaminants and observed adverse impacts remains poorly understood. The present study aimed to characterize the toxicological responses induced by persistent organic pollutants in wild-caught hornyhead turbot (P. verticalis). To do so, hornyhead turbot were interperitoneally injected with a single dose of PCB or PBDE congeners prepared using environmentally realistic mixture proportions. After 96-hour exposure, the livers were excised and analyzed using transcriptomic approaches and analytical chemistry. Concentrations of PCBs and PBDEs measured in the livers indicated clear differences across treatments, and congener profiles closely mirrored our expectations. Distinct gene profiles were characterized for PCB and PBDE exposed fish, with significant differences observed in the expression of genes associated with immune responses, endocrine-related functions, and lipid metabolism. Our findings highlight the key role that transcriptomics can play in monitoring programs to assess chemical-induced toxicity in heterogeneous group of fish (mixed gender and life stage) as is typically found during field surveys. Altogether, the present study provides further evidence of the potential of transcriptomic tools to improve aquatic health assessment and identify causative agents.

Ex situ determination of freely dissolved concentrations of hydrophobic organic chemicals in sediments and soils: basis for interpreting toxicity and assessing bioavailability, risks and remediation necessity

The freely dissolved concentration (C_free) of hydrophobic organic chemicals in sediments and soils is considered the driver behind chemical bioavailability and, ultimately, toxic effects in benthic organisms. Therefore, quantifying C_free, although challenging, is critical when assessing risks of contamination in field and spiked sediments and soils (e.g., when judging remediation necessity or interpreting results of toxicity assays performed for chemical safety assessments). Here, we provide a state-of-the-art passive sampling protocol for determining C_free in sediment and soil samples. It represents an international consensus procedure, developed during a recent interlaboratory comparison study. The protocol describes the selection and preconditioning of the passive sampling polymer, critical incubation system component dimensions, equilibration and equilibrium condition confirmation, quantitative sampler extraction, quality assurance/control issues and final calculations of C_free. The full procedure requires several weeks (depending on the sampler used) because of prolonged equilibration times. However, hands-on time, excluding chemical analysis, is approximately 3 d for a set of about 15 replicated samples.

Apex marine predators and ocean health: Proactive screening of halogenated organic contaminants reveals ecosystem indicator species

Despite decades-long bans on the production and use of certain chemicals, many halogenated organic compounds (HOCs) are persistent and can bioaccumulate in the marine environment with the potential to cause physiological harm to marine fauna. Highly lipid-rich tissue (e.g., marine mammal blubber) functions as a reservoir for HOCs, and selecting ideal indicator species is a priority for retrospective and proactive screening efforts. We selected five marine mammal species as possible indicators for the Southern California Bight (SCB) and applied a non-targeted analytical method paired with an automated data reduction strategy to catalog a broad range of known, known but unexpected, and unknown compounds in their blubber. A total of 194 HOCs were detected across the study species (n = 25 individuals), 81% of which are not routinely monitored, including 30 halogenated natural products and 45 compounds of unknown structure and origin. The cetacean species (long-beaked common dolphin, short-beaked common dolphin, and Risso's dolphin) averaged 128 HOCs, whereas pinnipeds (California sea lion and Pacific harbor seal) averaged 47 HOCs. We suspect this disparity can be attributed to differences in life history, foraging strategies, and/or enzyme-mediated metabolism. Our results support proposing (1) the long- and short-beaked common dolphin as apex marine predator sentinels for future and retrospective biomonitoring of the SCB ecosystem and (2) the use of non-targeted contaminant analyses to identify and prioritize emerging contaminants. The use of a sentinel marine species together with the non-targeted analytical approach will enable a proactive approach to environmental contaminant monitoring.

An exponential model based new approach for correcting aqueous concentrations of hydrophobic organic chemicals measured by polyethylene passive samplers

Although low density polyethylene (PE) passive samplers show promise for the measurement of aqueous phase hydrophobic organic chemicals (HOCs), the lack of a practical and unsophisticated approach to account for non-equilibrium exposure conditions has impeded widespread acceptance and thus application in situ. The goal of this study was to develop a streamlined approach based on an exponential model and a convection mass transfer principle for correcting aqueous concentrations for HOCs deduced by PE samplers under non-equilibrium conditions. First, uptake rate constants (k₁), elimination rate constants (k₂), and seawater-PE equilibrium partition coefficients (K_PEWs) were determined in laboratory experiments for a diverse suite of HOCs with logK_ow range of 3.4-8.3. Linear relationships between log k₂ and logK_ow, and between log K_PEW and logK_ow were established. Second, PE samplers pre-loaded with ¹³C-labeled performance reference compounds (PRCs) were deployed in the ocean to determine their k₂in situ. By applying boundary layer and convection mass transfer theories, ratio (C) of k₂ values in field and laboratory exposures was estimated. This C value was demonstrated a constant that was only determined by water velocities and widths of PE strips. A generic equation with C and logK_ow as parameters was eventually established for extrapolation of non-equilibrium correction factors for the water boundary layer-controlled HOCs. Characterizing the hydrodynamic conditions indicated the sampler configuration and mooring mode should aim at sustaining laminar flow on the PE surface for optimal mass transfer. The PE estimates corrected using this novel approach possessed high accuracy and acceptable precision, and can be suited for a broad spectrum of HOCs. The presented method should facilitate routine utilization of the PE samplers.

Advancing the Use of Passive Sampling in Risk Assessment and Management of Sediments Contaminated with Hydrophobic Organic Chemicals: Results of an International Ex Situ Passive Sampling Interlaboratory Comparison

This work presents the results of an international interlaboratory comparison on ex situ passive sampling in sediments. The main objectives were to map the state of the science in passively sampling sediments, identify sources of variability, provide recommendations and practical guidance for standardized passive sampling, and advance the use of passive sampling in regulatory decision making by increasing confidence in the use of the technique. The study was performed by a consortium of 11 laboratories and included experiments with 14 passive sampling formats on 3 sediments for 25 target chemicals (PAHs and PCBs). The resulting overall interlaboratory variability was large (a factor of ∼10), but standardization of methods halved this variability. The remaining variability was primarily due to factors not related to passive sampling itself, i.e., sediment heterogeneity and analytical chemistry. Excluding the latter source of variability, by performing all analyses in one laboratory, showed that passive sampling results can have a high precision and a very low intermethod variability (<factor of 1.7). It is concluded that passive sampling, irrespective of the specific method used, is fit for implementation in risk assessment and management of contaminated sediments, provided that method setup and performance, as well as chemical analyses are quality-controlled.

Linking in vitro estrogenicity to adverse effects in the inland silverside (Menidia beryllina)

High-throughput cell assays that detect and integrate the response of multiple chemicals acting via a common mode of action have the potential to enhance current environmental monitoring practices. Establishing the linkage between in vitro and in vivo responses is key to demonstrating that in vitro cell assays can be predictive of ecologically relevant outcomes. The present study investigated the potency of 17β-estradiol (E2), estrone (E1), nonylphenol (NP), and treated wastewater effluent using the readily available GeneBLAzer^® estrogen receptor transactivation assay and 2 life stages of the inland silverside (Menidia beryllina). In vitro estrogenic potencies were ranked as follows: E2 > E1 >> NP. All 3 model estrogens induced vitellogenin and choriogenin expression in a dose-dependent manner in larvae and juveniles. However, apical effects were only found for E2 and E1 exposures of juveniles, which resulted in female-skewed sex ratios. Wastewater effluent samples exhibiting low in vitro estrogenicity (below the 10% effective concentration [EC10]), did not cause significant changes in M. beryllina. Significant induction of estrogen-responsive genes was observed at concentrations 6 to 26 times higher than in vitro responses. Gonadal feminization occurred at concentrations at least 19 to 26 times higher than the in vitro responses. These findings indicated that in vitro cell assays were more sensitive than the fish assays, making it possible to develop in vitro effect thresholds protective of aquatic organisms. Environ Toxicol Chem 2018;37:884-892. © 2017 SETAC.

High throughput in vitro and in vivo screening of inland waters of Southern California

The impact of unmonitored contaminants, also known as contaminants of emerging concern (CECs), on freshwater streams remains largely uncharacterized. Water samples from 31 streams representing urban, agricultural and undeveloped (i.e., open space) land use in Southern California (USA) were analyzed for in vitro and in vivo bioactivity. The extent and magnitude of bioactivity screened using endocrine-responsive cell bioassays and a fish embryo screening assay were low. In contrast, a wider gradient of responses for the aryl hydrocarbon receptor (AhR) assay was observed, which was negatively correlated with a measure of benthic community structure. Both aromatic and non-aromatic CECs were tentatively identified in these samples, but polycyclic aromatic hydrocarbons (PAHs), known AhR agonists in urban environments, were not present at detectable levels. These results suggest that a combination of in vitro and in vivo show potential as screening techniques for biological condition in situ, but that more advanced, comprehensive analytical methods are needed to identify bioactive contaminants.

Nontargeted Screening of Halogenated Organic Compounds in Bottlenose Dolphins (Tursiops truncatus) from Rio de Janeiro, Brazil

To catalog the diversity and abundance of halogenated organic compounds (HOCs) accumulating in high trophic marine species from the southwestern Atlantic Ocean, tissue from bottlenose dolphins (Tursiops truncatus) stranded or incidentally captured along the coast of Rio de Janeiro, Brazil, were analyzed by a nontargeted approach based on GC×GC/TOF-MS. A total of 158 individual HOCs from 32 different structural classes were detected in the blubber of 4 adult male T. truncatus. Nearly 90% of the detected compounds are not routinely monitored in the environment. DDT-related and mirex/dechlorane-related compounds were the most abundant classes of anthropogenic origin. Methoxy-brominated diphenyl ethers (MeO-BDEs) and chlorinated methyl- and dimethyl bipyrroles (MBPs and DMBPs) were the most abundant natural products. Reported for the first time in southwestern Atlantic cetaceans and in contrast to North American marine mammals, chlorinated MBPs and DMBPs were more abundant than their brominated and/or mixed halogenated counterparts. HOC profiles in coastal T. truncatus from Brazil and California revealed a distinct difference, with a higher abundance of MeO-BDEs, mirex/dechloranes and chlorinated bipyrroles in the Brazilian dolphins. Thirty-six percent of the detected HOCs had an unknown structure. These results suggest broad geographical differences in the patterns of bioaccumulative chemicals found in the marine environment and indicate the need to develop more complete catalogs of HOCs from various marine environments.

A New Film-Based Passive Sampler for Moderately Hydrophobic Organic Compounds

Passive samplers for moderately hydrophobic organic compounds (MHOCs) (i.e., log K_ow ranging from 2 to 5) are under-developed compared to those that target polar or strongly hydrophobic compounds. The goal of this study was to identify a suitable polymer and develop a robust and sensitive film-based passive sampler for MHOCs in aquatic systems. Poly(methyl methacrylate) (PMMA) exhibited the highest affinity for fipronil and its three metabolites (i.e., fipronils) (log K_ow 2.4-4.8) as model MHOCs compared with polyethylene and nylon films. In addition, a 30-60 min treatment of PMMA in ethyl ether was found to increase its sorption capacity by a factor of 10. Fipronils and 108 additional compounds (log K_ow 2.4-8.5) reached equilibrium on solvent-treated PMMA within 120 h under mixing conditions and their uptake closely followed first-order kinetics. PMMA-water partition coefficients and K_ow revealed an inverse parabolic relationship, with vertex at log K_ow of 4.21 ± 0.19, suggesting that PMMA was ideal for MHOCs. The PMMA sampler was tested in an urban surface stream, and in spiked sediment. The results demonstrated that PMMA film, after a simple solvent swelling treatment, may be used as an effective passive sampler for determining C_free of MHOCs in aquatic environments.

Screening for Endocrine Activity in Water Using Commercially-available In Vitro Transactivation Bioassays

In vitro transactivation bioassays have shown promise as water quality monitoring tools, however their adoption and widespread application has been hindered partly due to a lack of standardized methods and availability of robust, user-friendly technology. In this study, commercially available, division-arrested cell lines were employed to quantitatively screen for endocrine activity of chemicals present in water samples of interest to environmental quality professionals. A single, standardized protocol that included comprehensive quality assurance/quality control (QA/QC) checks was developed for Estrogen and Glucocorticoid Receptor activity (ER and GR, respectively) using a cell-based Fluorescence Resonance Energy Transfer (FRET) assay. Samples of treated municipal wastewater effluent and surface water from freshwater systems in California (USA), were extracted using solid phase extraction and analyzed for endocrine activity using the standardized protocol. Background and dose-response for endpoint-specific reference chemicals met QA/QC guidelines deemed necessary for reliable measurement. The bioassay screening response for surface water samples was largely not detectable. In contrast, effluent samples from secondary treatment plants had the highest measurable activity, with estimated bioassay equivalent concentrations (BEQs) up to 392 ng dexamethasone/L for GR and 17 ng 17β-estradiol/L for ER. The bioassay response for a tertiary effluent sample was lower than that measured for secondary effluents, indicating a lower residual of endocrine active chemicals after advanced treatment. This protocol showed that in vitro transactivation bioassays that utilize commercially available, division-arrested cell "kits", can be adapted to screen for endocrine activity in water.

Newly Identified DDT-Related Compounds Accumulating in Southern California Bottlenose Dolphins

Nontargeted GC×GC-TOF/MS analysis of blubber from 8 common bottlenose dolphins (Tursiops truncatus) inhabiting the Southern California Bight was performed to identify novel, bioaccumulative DDT-related compounds and to determine their abundance relative to the commonly studied DDT-related compounds. We identified 45 bioaccumulative DDT-related compounds of which the majority (80%) is not typically monitored in environmental media. Identified compounds include transformation products, technical mixture impurities such as tris(chlorophenyl)methane (TCPM), the presumed TCPM metabolite tris(chlorophenyl)methanol (TCPMOH), and structurally related compounds with unknown sources, such as hexa- to octachlorinated diphenylethene. To investigate impurities in pesticide mixtures as possible sources of these compounds, we analyzed technical DDT, the primary source of historical contamination in the region, and technical Dicofol, a current use pesticide that contains DDT-related compounds. The technical mixtures contained only 33% of the compounds identified in the blubber, suggesting that transformation products contribute to the majority of the load of DDT-related contaminants in these sentinels of ocean health. Quantitative analysis revealed that TCPM was the second most abundant compound class detected in the blubber, following DDE, and TCPMOH loads were greater than DDT. QSPR estimates verified 4,4',4″-TCPM and 4,4'4,″-TCPMOH are persistent and bioaccumulative.

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

To examine the occurrence and fate of contaminants of emerging concern (CECs) and inform future monitoring of CECs in coastal urban waterways, water, sediment, and fish tissue samples were collected and analyzed for a broad suite of pharmaceuticals and personal care products (PPCPs), commercial and/or household chemicals, current use pesticides, and hormones in an effluent-dominated river and multiple embayments in southern California (USA). In the Santa Clara River, which receives treated wastewater from several facilities, aqueous phase CECs were detectable at stations nearest discharges from municipal wastewater treatment plants but were attenuated downstream. Sucralose and the chlorinated phosphate flame retardants tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), and tris(2-chloroethyl) phosphate (TCEP) were most abundant in water, with maximum concentrations of 35 μg/L, 3.3 μg/L, 1.4 μg/L, and 0.81 μg/L, respectively. Triclocarban, an antimicrobial agent in use for decades, was more prevalent in water than triclosan or nonylphenol. Maximum concentrations of bifenthrin, permethrin, polybrominated diphenyl ethers (PBDEs), and degradates of fipronil exceeded CEC-specific monitoring trigger levels recently established for freshwater and estuarine sediments by factors of 10 to 1000, respectively. Maximum fish tissue concentrations of PBDEs varied widely (370 ng/g and 7.0 ng/g for the Santa Clara River and coastal embayments, respectively), with most species exhibiting concentrations at the lower end of this range. These results suggest that continued monitoring of pyrethroids, PBDEs, and degradates of fipronil in sediment is warranted in these systems. In contrast, aqueous pharmaceutical concentrations in the Santa Clara River were not close to exceeding current monitoring trigger levels, suggesting a lower priority for targeted monitoring in this medium. Environ Toxicol Chem 2016;35:1986-1994. © 2016 SETAC.

A tiered, integrated biological and chemical monitoring framework for contaminants of emerging concern in aquatic ecosystems

The chemical-specific risk-based paradigm that informs monitoring and assessment of environmental contaminants does not apply well to the many thousands of new chemicals that are being introduced into ambient receiving waters. We propose a tiered framework that incorporates bioanalytical screening tools and diagnostic nontargeted chemical analysis to more effectively monitor for contaminants of emerging concern (CECs). The framework is based on a comprehensive battery of in vitro bioassays to first screen for a broad spectrum of CECs and nontargeted analytical methods to identify bioactive contaminants missed by the currently favored targeted analyses. Water quality managers in California have embraced this strategy with plans to further develop and test this framework in regional and statewide pilot studies on waterbodies that receive discharge from municipal wastewater treatment plants and stormwater runoff. In addition to directly informing decisions, the data obtained using this framework can be used to construct and validate models that better predict CEC occurrence and toxicity. The adaptive interplay among screening results, diagnostic assessment and predictive modeling will allow managers to make decisions based on the most current and relevant information, instead of extrapolating from parameters with questionable linkage to CEC impacts. Integr Environ Assess Manag 2016;12:540-547. © 2015 SETAC.

Trophic transfer and effects of DDT in male hornyhead turbot (Pleuronichthys verticalis) from Palos Verdes Superfund site, CA (USA) and comparisons to field monitoring

High concentrations of DDT and metabolites (ΣDDT) have been detected in sediment and the demersal flatfish hornyhead turbot (Pleuronichtys verticalis) collected from Palos Verdes (PV), California, USA, a site contaminated with over 100 metric tons of DDT throughout 1960s-70s. This study was conducted to assess the transfer of ΣDDT from PV-sediment into polychaetes (Neanthes arenaceodentata) and hornyhead turbot, and to investigate if the responses in turbots from two different laboratory exposures mimic those in turbots caught in PV (PV-turbot). Turbot fed PV-sediment-contaminated polychaete for 7 days had liver concentrations of ΣDDT similar to PV-turbot. After 28 days, ΣDDT also accumulated in livers of turbot gavaged with a ΣDDT mixture. In vitro cell bioassays indicated significant increases of 17β-estradiol equivalents (EEQ) in turbot bile extracts as compared to the control in the 7-day study. These responses corresponded to those measured in PV-fish. Glucocorticoid receptor (GR), anti-androgen receptor (anti-AR), estrogen receptor (ER) or aryl hydrocarbon receptor (AhR) activities were also observed in extracts of PV-sediment, and PV-sediment-exposed worm. Anti-AR, AhR and GR activities were significantly higher in PV-sediment than reference sediment (San Diego, SD). Higher transcripts of hepatic VTG, ERα and ERβ were found in PV-turbot than SD-turbot, but were unaltered in fish exposed to sediment-contaminated worms for the 7-day study. In contrast, liver extracts from the 28-day treatment of ΣDDT showed lower EEQ but similar hepatic VTG and ERβ transcripts relative to those of PV-turbot. These data indicated that trophic transfer of sediment-associated DDT in 7-day exposures corresponded to field measurements of DDT residues and in vitro ER bioactivities, but failed to mimic in vivo biological effects observed in field fish. In contrast, treatment with ΣDDT alone for 28 days mimicked in vivo biological effects of DDTs in PV fish, but did not correspond to liver concentrations or in vitro bioactivities.

Interlaboratory comparison of in vitro bioassays for screening of endocrine active chemicals in recycled water

In vitro bioassays have shown promise as water quality monitoring tools. In this study, four commercially available in vitro bioassays (GeneBLAzer(®) androgen receptor (AR), estrogen receptor-alpha (ER), glucocorticoid receptor (GR) and progesterone receptor (PR) assays) were adapted to screen for endocrine active chemicals in samples from two recycled water plants. The standardized protocols were used in an interlaboratory comparison exercise to evaluate the reproducibility of in vitro bioassay results. Key performance criteria were successfully achieved, including low background response, standardized calibration parameters and high intra-laboratory precision. Only two datasets were excluded due to poor calibration performance. Good interlaboratory reproducibility was observed for GR bioassay, with 16-26% variability among the laboratories. ER and PR bioactivity was measured near the bioassay limit of detection and showed more variability (21-54%), although interlaboratory agreement remained comparable to that of conventional analytical methods. AR bioassay showed no activity for any of the samples analyzed. Our results indicate that ER, GR and PR, were capable of screening for different water quality, i.e., the highest bioactivity was observed in the plant influent, which also contained the highest concentrations of endocrine active chemicals measured by LC-MS/MS. After advanced treatment (e.g., reverse osmosis), bioactivity and target chemical concentrations were both below limits of detection. Comparison of bioassay and chemical equivalent concentrations revealed that targeted chemicals accounted for ≤5% of bioassay activity, suggesting that detection limits by LC-MS/MS for some chemicals were insufficient and/or other bioactive compounds were present in these samples. Our study demonstrated that in vitro bioassays responses were reproducible, and can provide information to complement conventional analytical methods for a more comprehensive water quality assessment.

A passive sampler based on solid phase microextraction (SPME) for sediment-associated organic pollutants: Comparing freely-dissolved concentration with bioaccumulation

The elevated occurrence of hydrophobic organic chemicals (HOCs) such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCBs) and legacy organchlorine pesticides (e.g. chlordane and DDT) in estuarine sediments continues to poses challenges for maintaining the health of aquatic ecosystems. Current efforts to develop and apply protective, science-based sediment quality regulations for impaired waterbodies are hampered by non-concordance between model predictions and measured bioaccumulation and toxicity. A passive sampler incorporating commercially available solid phase microextraction (SPME) fibers was employed in lab and field studies to measure the freely dissolved concentration of target HOCs (Cfree) and determine its suitability as a proxy for bioaccumulation. SPME deduced Cfree for organochlorines was highly correlated with tissue concentrations (Cb) of Macoma and Nereis spp. co-exposed in laboratory microcosms containing both spiked and naturally contaminated sediments. This positive association was also observed in situ for endemic bivalves, where SPME samplers were deployed for up to 1 month at an estuarine field site. The concordance between Cb and Cfree for PAH was more variable, in part due to likely biotransformation by model invertebrates. These results indicate that SPME passive samplers can serve as a proxy for bioaccumulation of sediment-associated organochlorines in both lab and field studies, reducing the uncertainty associated with model predictions that do not adequately account for differential bioavailability.

Using performance reference compound-corrected polyethylene passive samplers and caged bivalves to measure hydrophobic contaminants of concern in urban coastal seawaters

Low-density polyethylene (PE) passive samplers containing performance reference compounds (PRCs) were deployed at multiple depths in two urban coastal marine locations to estimate dissolved concentrations of hydrophobic organic contaminants (HOCs), including dichlorodiphenyltrichloroethane (DDT) and its metabolites, polychlorinated biphenyl (PCB) congeners, and polybrominated flame retardants. PE samplers pre-loaded with PRCs were deployed at the surface, mid-column, and near bottom at sites representing 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, concentrations ranged up to 100 pg L(-1) for PCBs and polybrominated diphenyl ethers (PBDEs), 500 pg L(-1) for DDMU and 300 pg L(-1) for DDNU, and to 1000 pg L(-1) for p,p'-DDE. Seawater concentrations of DDTs and PCBs increased with depth, suggesting that bed sediments serve as the source of water column HOCs in Santa Monica Bay. In contrast, no discernable pattern between surface and near-bottom concentrations in Los Angeles Harbor was observed, which were also several-fold lower (DDTs: 45-300 pg L(-1), PCBs: 5-50 pg L(-1)) than those in Santa Monica Bay (DDTs: 2-1100 pg L(-1), PCBs: 2-250 pg L(-1)). Accumulation by mussels co-deployed with the PE samplers at select sites was strongly correlated with PE-estimated seawater concentrations, providing further evidence that these samplers are a viable alternative for monitoring of HOC exposure. Fractional equilibration observed with the PRCs increased with decreasing PRC molar volume indicating the importance of target compound physicochemical properties when estimating water column concentrations using passive samplers in situ.

Which coastal and marine environmental contaminants are truly emerging?

To better understand the past and present impact of contaminants of emerging concern (CECs) in coastal and marine ecosystems, archived samples were analyzed for a broad suite of analytes, including pharmaceuticals and personal care products (PPCPs), flame retardants (including PBDEs), perfluorinated compounds (PFCs), and current-use pesticides. Surface sediment, mussels (Mytilus spp.) and sediment core samples collected from the California (USA) coast were obtained from environmental specimen banks. Selected CECs were detected in recent surface sediments, with nonylphenol (4-NP), its mono- and di-ethoxylates (NP1EO and NP2EO), triclocarban, and pyrethroid insecticides in the greatest abundance. Alkylphenols, triclocarban, and triclosan were present in sediment core segments from the 1970s, as well as in Mytilus tissue collected during the 1990s. Increasing concentrations of some CECs (e.g., miconazole, triclosan) were observed in the surface layers (ca. 2007) of a sediment core, in contrast to peak concentrations of 4-NP and triclocarban corresponding to input during the 1970s, and an apparent peak input for PBDEs during the 1990s. These results suggest that chemicals sometimes referred to as "emerging" (e.g., alkylphenols, triclocarban) have been present in the aquatic environment for several decades and are decreasing in concentration, whereas others (e.g., miconazole, triclosan) are increasing.

The Mussel Watch California pilot study on contaminants of emerging concern (CECs): synthesis and next steps

A multiagency pilot study on mussels (Mytilus spp.) collected at 68 stations in California revealed that 98% of targeted contaminants of emerging concern (CECs) were infrequently detectable at concentrations ≤ 1 ng/g. Selected chemicals found in commercial and consumer products were more frequently detected at mean concentrations up to 470 ng/g dry wt. The number of CECs detected and their concentrations were greatest for stations categorized as urban or influenced by storm water discharge. Exposure to a broader suite of CECs was also characterized by passive sampling devices (PSDs), with estimated water concentrations of hydrophobic compounds correlated with Mytilus concentrations. The results underscore the need for focused CEC monitoring in coastal ecosystems and suggest that PSDs are complementary to bivalves in assessing water quality. Moreover, the partnership established among participating agencies led to increased spatial coverage, an expanded list of analytes and a more efficient use of available resources.

Occurrence of contaminants of emerging concern in mussels (Mytilus spp.) along the California coast and the influence of land use, storm water discharge, and treated wastewater effluent

Contaminants of emerging concern were measured in mussels collected along the California coast in 2009-2010. The seven classes were alkylphenols, pharmaceuticals and personal care products, polybrominated diphenyl ethers (PBDE), other flame retardants, current use pesticides, perfluorinated compounds (PFC), and single walled carbon nanotubes. At least one contaminant was detected at 67 of the 68 stations (98%), and 67 of the 167 analytes had at least one detect (40%). Alkylphenol, PBDE, and PFC concentrations increased with urbanization and proximity to storm water discharge; pesticides had higher concentrations at agricultural stations. These results suggest that certain compounds; for example, alkylphenols, lomefloxacin and PBDE, are appropriate for inclusion in future coastal bivalve monitoring efforts based on maximum concentrations >50 ng/g dry weight and detection frequencies >50%. Other compounds, for example PFC and hexabromocyclododecane (HBCD), may also be suggested for inclusion due to their >25% detection frequency and potential for biomagnification.

Occurrence of contaminants of emerging concern along the California coast (2009-10) using passive sampling devices

Three passive sampling devices (PSDs), polar organic chemical integrative samplers (POCIS), polyethylene devices (PEDs), and solid-phase microextraction (SPME) samplers were used to sample a diverse set of chemicals in the coastal waters of San Francisco Bay and the Southern California Bight. Seventy one chemicals (including fragrances, phosphate flame retardants, pharmaceuticals, PAHs, PCBs, PBDEs, and pesticides) were measured in at least 50% of the sites. The chemical profile from the San Francisco Bay sites was distinct from profiles from the sites in the Southern California Bight. This distinction was not due to a single compound or class, but by the relative abundances/concentrations of the chemicals. Comparing the PSDs to mussel (Mytilus spp.) tissues, a positive correlation exists for the 25 and 26 chemicals in common for the PEDs and SPME, respectively. Diphenhydramine was the only common chemical out of 40 analyzed in both POCIS and tissues detected at a common site.

Refocusing Mussel Watch on contaminants of emerging concern (CECs): the California pilot study (2009-10)

To expand the utility of the Mussel Watch Program, local, regional and state agencies in California partnered with NOAA to design a pilot study that targeted contaminants of emerging concern (CECs). Native mussels (Mytilus spp.) from 68 stations, stratified by land use and discharge scenario, were collected in 2009-10 and analyzed for 167 individual pharmaceuticals, industrial and commercial chemicals and current use pesticides. Passive sampling devices (PSDs) and caged Mytilus were co-deployed to expand the list of CECs, and to assess the ability of PSDs to mimic bioaccumulation by Mytilus. A performance-based quality assurance/quality control (QA/QC) approach was developed to ensure a high degree of data quality, consistency and comparability. Data management and analysis were streamlined and standardized using automated software tools. This pioneering study will help shape future monitoring efforts in California's coastal ecosystems, while serving as a model for monitoring CECs within the region and across the nation.

Passive sampling methods for contaminated sediments: practical guidance for selection, calibration, and implementation

This article provides practical guidance on the use of passive sampling methods (PSMs) that target the freely dissolved concentration (Cfree ) for improved exposure assessment of hydrophobic organic chemicals in sediments. Primary considerations for selecting a PSM for a specific application include clear delineation of measurement goals for Cfree , whether laboratory-based "ex situ" and/or field-based "in situ" application is desired, and ultimately which PSM is best-suited to fulfill the measurement objectives. Guidelines for proper calibration and validation of PSMs, including use of provisional values for polymer-water partition coefficients, determination of equilibrium status, and confirmation of nondepletive measurement conditions are defined. A hypothetical example is described to illustrate how the measurement of Cfree afforded by PSMs reduces uncertainty in assessing narcotic toxicity for sediments contaminated with polycyclic aromatic hydrocarbons. The article concludes with a discussion of future research that will improve the quality and robustness of Cfree measurements using PSMs, providing a sound scientific basis to support risk assessment and contaminated sediment management decisions.

Calculating the diffusive flux of persistent organic pollutants between sediments and the water column on the Palos Verdes shelf superfund site using polymeric passive samplers

Passive samplers were deployed to the seafloor at a marine Superfund site on the Palos Verdes Shelf, California, USA, and used to determine water concentrations of persistent organic pollutants (POPs) in the surface sediments and near-bottom water. A model of Fickian diffusion across a thin water boundary layer at the sediment-water interface was used to calculate flux of contaminants due to molecular diffusion. Concentrations at four stations were used to calculate the flux of DDE, DDD, DDMU, and selected PCB congeners from sediments to the water column. Three passive sampling materials were compared: PE strips, POM strips, and SPME fibers. Performance reference compounds (PRCs) were used with PE and POM to correct for incomplete equilibration, and the resulting POP concentrations, determined by each material, agreed within 1 order of magnitude. SPME fibers, without PRC corrections, produced values that were generally much lower (1 to 2 orders of magnitude) than those measured using PE and POM, indicating that SPME may not have been fully equilibrated with waters being sampled. In addition, diffusive fluxes measured using PE strips at stations outside of a pilot remedial sand cap area were similar to those measured at a station inside the capped area: 240 to 260 ng cm(-2) y(-1) for p,p'-DDE. The largest diffusive fluxes of POPs were calculated at station 8C, the site where the highest sediment concentrations have been measured in the past, 1100 ng cm(-2) y(-1) for p,p'-DDE.

Passive sampling in contaminated sediment assessment: building consensus to improve decision making

Contaminated sediments pose an ongoing, pervasive, global challenge to environmental managers, because sediments can reflect a legacy of pollution that can impair the beneficial uses of water bodies. A formidable challenge in assessing the risks of contaminated sediments has been the elucidation and measurement of contaminant bioavailability, expressed as the freely dissolved concentration (Cfree ) in interstitial water, which serves as a surrogate measure of the substances' chemical activity. Recent advances in passive sampling methods (PSMs) enable Cfree of sediment-associated contaminants to be quantified at trace levels, thereby overcoming current limitations of predictive models. As a result, PSMs afford the opportunity for a paradigm shift from traditional practice that can effectively reduce uncertainty in risk assessment and bolster confidence in the science used to support management of contaminated sediments. This paper provides a brief overview of the 5 subsequent papers in this series that review literature on PSM use in sediments for both organic and metal(loid) contaminants, outline the technical rationale for using PSMs as a preferred basis for risk assessment over conventional chemical analyses, describe practical considerations for and uncertainties associated with laboratory and field deployment of PSMs, discuss management application of PSMs, including illustrative case studies in which PSMs have been used in decision making, and highlight future research and communication needs.

Passive sampling methods for contaminated sediments: state of the science for organic contaminants

This manuscript surveys the literature on passive sampler methods (PSMs) used in contaminated sediments to assess the chemical activity of organic contaminants. The chemical activity in turn dictates the reactivity and bioavailability of contaminants in sediment. Approaches to measure specific binding of compounds to sediment components, for example, amorphous carbon or specific types of reduced carbon, and the associated partition coefficients are difficult to determine, particularly for native sediment. Thus, the development of PSMs that represent the chemical activity of complex compound-sediment interactions, expressed as the freely dissolved contaminant concentration in porewater (Cfree ), offer a better proxy for endpoints of concern, such as reactivity, bioaccumulation, and toxicity. Passive sampling methods have estimated Cfree using both kinetic and equilibrium operating modes and used various polymers as the sorbing phase, for example, polydimethylsiloxane, polyethylene, and polyoxymethylene in various configurations, such as sheets, coated fibers, or vials containing thin films. These PSMs have been applied in laboratory exposures and field deployments covering a variety of spatial and temporal scales. A wide range of calibration conditions exist in the literature to estimate Cfree , but consensus values have not been established. The most critical criteria are the partition coefficient between water and the polymer phase and the equilibrium status of the sampler. In addition, the PSM must not appreciably deplete Cfree in the porewater. Some of the future challenges include establishing a standard approach for PSM measurements, correcting for nonequilibrium conditions, establishing guidance for selection and implementation of PSMs, and translating and applying data collected by PSMs.

The use of sediment toxicity identification evaluation methods to evaluate clean up targets in an urban estuary

The Ballona Creek Estuary (BCE) in Los Angeles, California, is in a highly urbanized watershed, is contaminated by a variety of chemicals, and has prevalent sediment toxicity. Sediment cleanup targets for BCE have been established for Cu, Cd, Pb, Zn, chlordane, DDTs, PCBs, and PAHs, based on sediment quality guidelines. A sediment toxicity identification evaluation (TIE) was conducted to examine how these targets corresponded to toxicity observed with the estuarine amphipod Eohaustorius estuarius. Whole sediment and porewater TIEs were used to identify the cause of toxicity. Passive samplers were deployed to determine the bioavailable fraction of contaminants. Spiked sediment tests were conducted to determine the thresholds of toxicity for selected constituents. Toxicity was found to be widespread but temporally and spatially variable. Whole sediment and porewater TIEs both indicated pyrethroid pesticides were the most likely contaminant group contributing to the toxicity. Concentrations of the chemicals listed for cleanup were found to often exceed target values but were not observed at concentrations likely to cause toxicity. Bioavailable fractions of the target chemicals quantified using passive samplers did not exceed toxicity thresholds. Spiked sediment tests established 10 day LC50s for 4,4' DDE, 4, 4' DDT, α-chlordane, and cyfluthrin at >3050 μg/g, 266 μg/g, >2120 μg/g, and 0.33 μg/g organic carbon (OC), respectively. The cyfluthrin LC50 was within the range of concentrations observed in the estuary sediments, but LC50s for the other 3 chemicals were orders of magnitude greater than observed levels. The combination of TIE, sediment chemistry and the results from spiked sediment exposures indicate pyrethroid pesticides are more likely the cause of the observed toxicity than any of the contaminants targeted for cleanup. The results of this study indicate the importance of using a TIE approach to determine chemicals of concern and dose-response information to set cleanup targets, rather than using sediment quality guidelines. Integr Environ Assess Manag 2014;10:260-268. © 2013 SETAC.

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

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.

Benchmarking organic micropollutants in wastewater, recycled water and drinking water with in vitro bioassays

Thousands of organic micropollutants and their transformation products occur in water. Although often present at low concentrations, individual compounds contribute to mixture effects. Cell-based bioassays that target health-relevant biological endpoints may therefore complement chemical analysis for water quality assessment. The objective of this study was to evaluate cell-based bioassays for their suitability to benchmark water quality and to assess efficacy of water treatment processes. The selected bioassays cover relevant steps in the toxicity pathways including induction of xenobiotic metabolism, specific and reactive modes of toxic action, activation of adaptive stress response pathways and system responses. Twenty laboratories applied 103 unique in vitro bioassays to a common set of 10 water samples collected in Australia, including wastewater treatment plant effluent, two types of recycled water (reverse osmosis and ozonation/activated carbon filtration), stormwater, surface water, and drinking water. Sixty-five bioassays (63%) showed positive results in at least one sample, typically in wastewater treatment plant effluent, and only five (5%) were positive in the control (ultrapure water). Each water type had a characteristic bioanalytical profile with particular groups of toxicity pathways either consistently responsive or not responsive across test systems. The most responsive health-relevant endpoints were related to xenobiotic metabolism (pregnane X and aryl hydrocarbon receptors), hormone-mediated modes of action (mainly related to the estrogen, glucocorticoid, and antiandrogen activities), reactive modes of action (genotoxicity) and adaptive stress response pathway (oxidative stress response). This study has demonstrated that selected cell-based bioassays are suitable to benchmark water quality and it is recommended to use a purpose-tailored panel of bioassays for routine monitoring.

An adaptive, comprehensive monitoring strategy for chemicals of emerging concern (CECs) in California's Aquatic Ecosystems

A scientific advisory panel was convened by the State of California to recommend monitoring for chemicals of emerging concern (CECs) in aquatic systems that receive discharge of municipal wastewater treatment plant (WWTP) effluent and stormwater runoff. The panel developed a risk-based screening framework that considered environmental sources and fate of CECs observed in receiving waters across the State. Using existing occurrence and risk threshold data in water, sediment, and biological tissue, the panel applied the framework to identify a priority list of CECs for initial monitoring in three representative receiving water scenarios. The initial screening list of 16 CECs identified by the panel included consumer and commercial chemicals, flame retardants, pesticides, pharmaceuticals and personal care products, and natural hormones. The panel designed an iterative, phased strategy with interpretive guidelines that direct and update management actions commensurate with potential risk identified using the risk-based framework and monitoring data. Because of the ever-changing nature of chemical use, technology, and management practices, the panel offered recommendations to improve CEC monitoring, including development of bioanalytical screening methods whose responses integrate exposure to complex mixtures and that can be linked to higher-order effects; development or refinement of models that predict the input, fate, and effects of future chemicals; and filling of key data gaps on CEC occurrence and toxicity. Finally, the panel stressed the need for adaptive management, allowing for future review of, and if warranted, modifications to the strategy to incorporate the latest science available to the water resources community.

Designing monitoring programs for chemicals of emerging concern in potable reuse--what to include and what not to include?

This study discussed a proposed process to prioritize chemicals for reclaimed water monitoring programs, selection of analytical methods required for their quantification, toxicological relevance of chemicals of emerging concern regarding human health, and related issues. Given that thousands of chemicals are potentially present in reclaimed water and that information about those chemicals is rapidly evolving, a transparent, science-based framework was developed to guide prioritization of which compounds of emerging concern (CECs) should be included in reclaimed water monitoring programs. The recommended framework includes four steps: (1) compile environmental concentrations (e.g., measured environmental concentration or MEC) of CECs in the source water for reuse projects; (2) develop a monitoring trigger level (MTL) for each of these compounds (or groups thereof) based on toxicological relevance; (3) compare the environmental concentration (e.g., MEC) to the MTL; CECs with a MEC/MTL ratio greater than 1 should be prioritized for monitoring, compounds with a ratio less than '1' should only be considered if they represent viable treatment process performance indicators; and (4) screen the priority list to ensure that a commercially available robust analytical method is available for that compound.

The effect of co-occurring polychlorinated biphenyls on quantitation of toxaphene in fish tissue samples by gas chromatography negative ion mass spectrometry

Determinative methods based on gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS) provide improved sensitivity and specificity for toxaphene in environmental samples, but are subject to misidentification due to oxygen reaction in the presence of polychlorinated biphenyls (PCBs). The goal of this study was to quantify the impact of co-occurring PCBs in fish tissue samples when utilizing single quadrupole instruments to implement this method. Mixtures of PCB congeners and technical toxaphene, and extracts of fish tissue with varying concentrations of PCBs were analyzed for individual congener and total toxaphene concentrations by GC-NCI/MS. The contribution of co-injected PCB 204 ranged from 23% to 88% of the total peak area for the Cl-9 toxaphene homolog quantitation ion, a contribution that increased as the ratio of technical toxaphene to PCB 204 decreased. PCB interferences in fish tissue extracts, including a standard reference material, were subtracted using a three-step procedure featuring spectral analysis of isotopic patterns for target peaks. Total toxaphene concentrations without PCB subtraction in three fish tissue samples with low, intermediate and high co-occurring PCBs were overestimated by 33, 55 and 745%, respectively, underscoring the need for practical strategies to account for PCB interferences in GC-NCI/MS based protocols. In contrast, no appreciable interference or resulting positive bias in concentrations was observed for quantitation of eight common toxaphene residue congeners.

Organic contaminants of emerging concern in sediments and flatfish collected near outfalls discharging treated wastewater effluent to the Southern California Bight

To investigate the occurrence and bioaccumulation of organic contaminants of emerging concern (CECs) near four major wastewater ocean outfalls in the Southern California Bight, more than 75 pharmaceutical and personal care products, current-use pesticides, and industrial/commercial chemicals were analyzed in sediment and liver tissues of hornyhead turbot (Pleuronichthys verticalis) using gas and liquid chromatography-mass spectrometry. Although most CECs targeted were infrequently detected or not detectable, triclosan, 4-nonylphenol (4-NP) and bis(2-ethylhexylphthalate) were detected in all sediments at median (maximum) concentrations of 5.1 (8.6), 30 (380), and 121 (470) µg/kg, respectively. In the liver, 4-NP and polybrominated diphenyl ether (PBDE) congeners 47 and 99 were detected in >90% of samples at median (maximum) concentrations of 85 (290) and 210 (480) µg/kg, respectively. The sedative diazepam was detected in all liver samples, but was infrequently detected in sediments. Sediment and liver concentrations across outfall locations ranged over several orders of magnitude and were elevated relative to a reference site. Relative to sediment, accumulation in liver of PBDEs 47 and 99 was comparable to that for legacy organochlorines, confirming their high bioaccumulation potential and suggesting their inclusion in future tissue monitoring studies. Mean tissue PBDE and diazepam concentrations were higher in livers from male versus female P. verticalis, suggesting that gender differences also be considered in designing such studies.

Integrated coastal effects study: synthesis of findings

Municipal wastewater discharges constitute a major source of contaminants of emerging concern (CECs) to coastal waters, yet uncertainty exists regarding their linkage to adverse biological effects such as endocrine disruption. Limited information is available concerning the types and fate of CECs discharged to the Southern California Bight (SCB) from municipal wastewater and their potential for ecological impacts. The present study investigated the impacts of CECs from ocean wastewater discharges on SCB fish. Concentrations of CECs were measured in effluents from four major municipal wastewater dischargers. Seawater, sediment, and hornyhead turbot (Pleuronichthys verticalis) from the discharge sites and a reference area were collected and analyzed for chemical and biological indicators. Low concentrations of pharmaceuticals, personal care products, and industrial and commercial compounds were measured in effluent. Some CECs were also detected in sediment, seawater, and fish livers near the outfalls, confirming exposure to CECs. Fish plasma hormone analyses suggested the presence of physiological effects, including a reduced stress response, altered estrogen synthesis or estrogenic exposure, and reduced thyroxine. Most fish responses were found at all sites and could not be directly associated with effluent discharges. However, concentrations of thyroxine were lower at all discharge sites relative to the reference, and estradiol concentrations were lower at three of the four outfall sites. The physiological responses found were not associated with adverse impacts on fish reproduction or populations. Interpretation of molecular and physiological measurements in field organisms such as those used in the present study is challenging because of a lack of information on baseline conditions and uncertain linkages to apical endpoints such as survival and reproduction.

Passive sampling to measure baseline dissolved persistent organic pollutant concentrations in the water column of the Palos Verdes Shelf Superfund site

Passive sampling was used to deduce water concentrations of persistent organic pollutants (POPs) in the vicinity of a marine Superfund site on the Palos Verdes Shelf, California, USA. Precalibrated solid phase microextraction (SPME) fibers and polyethylene (PE) strips that were preloaded with performance reference compounds (PRCs) were codeployed for 32 d along an 11-station gradient at bottom, surface, and midwater depths. Retrieved samplers were analyzed for DDT congeners and their breakdown products (DDE, DDD, DDMU, and DDNU) and 43 PCB congeners using GC-EI- and NCI-MS. PRCs were used to calculate compound-specific fractional equilibration achieved in situ for the PE samplers, using both an exponential approach to equilibrium (EAE) and numerical integration of Fickian diffusion (NI) models. The highest observed concentrations were for p,p'-DDE, with 2200 and 990 pg/L deduced from PE and SPME, respectively. The difference in these estimates could be largely attributed to uncertainty in equilibrium partition coefficients, unaccounted for disequilibrium between samplers and water, or different time scales over which the samplers average. The concordance between PE and SPME estimated concentrations for DDE was high (R(2) = 0.95). PCBs were only detected in PE samplers, due to their much larger size. Near-bottom waters adjacent to and down current from sediments with the highest bulk concentrations exhibited aqueous concentrations of DDTs and PCBs that exceeded Ambient Water Quality Criteria (AWQC) for human and aquatic health, indicating the need for future monitoring to determine the effectiveness of remedial activities taken to reduce adverse effects of contaminated surface sediments.

Incorporating contaminant bioavailability into sediment quality assessment frameworks

The recently adopted sediment quality assessment framework for evaluating bay and estuarine sediments in the state of California incorporates bulk sediment chemistry as a key line of evidence (LOE) but does not address the bioavailability of measured contaminants. Thus, the chemistry-based LOE likely does not provide an accurate depiction of organism exposure in all cases, nor is it particularly well suited for assessment of causality. In recent years, several methods for evaluating the bioavailability of sediment-associated contaminants have emerged, which, if optimized and validated, could be applied to improve the applicability and broaden the scope of sediment quality assessment. Such methods include equilibrium-based biomimetic extractions using either passive sampling devices (PSDs) or measures of rapidly desorbing contaminant pools, which provide information compatible with existing mechanistic approaches. Currently, these methods show promise in relating bioaccessible chemicals to effects endpoints, including bioaccumulation of hydrophobic organic compounds and/or toxicity due to metals. Using these methods, a bioavailability LOE for organics is proposed based on PSD and equilibrium partitioning theory that can be employed as an independent LOE or in assessing causality in tiered toxicity identification evaluations. Current and future research should be aimed at comparing the performance of PSDs and their relationships with effects concentrations, field validation of the most promising methods, addressing contaminant mixtures, further developing the parameterization of the proposed bioavailability LOE, and providing a better understanding of the underlying diagenetic cycling of metal contaminants that lead to exposure, affect bioavailability, and drive adverse outcomes.

Distribution and sources of polybrominated diphenyl ethers in the Southern California Bight

Polybrominated diphenyl ethers (PBDEs) were measured in surface sediments from 121 locations within the Southern California Bight. Site selection was based on a probabilistic approach to determine the spatial extent and magnitude of PBDE concentrations with known confidence intervals. Coastal embayments (including estuaries, marinas, ports, and bays) and the continental shelf out to the lower slope were sampled. Thirteen PBDEs were detected at 92 of the sites, with a geometric mean and maximum of 4.7 and 560 ng/g dry weight (sum of 13 congeners), respectively. The PBDE concentrations were higher in coastal embayments than in offshore locations. Embayments had an area-weighted geometric mean total PBDE concentration of 12 (95% confidence interval, 8.0-17) ng/g dry weight and a total PBDE mass of 110 (77-160) kg. The offshore stratum, which is 99% of the total area, had an area-weighted geometric mean total PBDE concentration of 2.0 (1.6-2.5) ng/g dry weight and a total PBDE mass of 860 (700-1,100) kg. The five highest PBDE concentrations were associated with the mouths of urban rivers, indicating that urban runoff is likely a major input of PBDEs to these coastal marine waters. The outfalls of wastewater treatment plants were not observed to be major sources.

Nontargeted comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry method and software for inventorying persistent and bioaccumulative contaminants in marine environments

Analytical methods for contaminant monitoring are generally targeted; i.e., they measure defined lists of compounds. Routine monitoring projects using targeted methods are not usually designed to screen for unrecognized or novel contaminants and therefore miss compounds within the region or population of study that cause, or have the potential to cause, adverse biological impacts. We describe a nontargeted analytical method utilizing direct sample introduction coupled to comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry. To test the capabilities of this instrumental method within the context of marine contaminant surveys, we characterized a broad array of nonpolar, persistent, and bioaccumulative contaminants in Atlantic common dolphin ( Delphinus delphis ) blubber, including compounds that are not typically monitored. Compound identifications were made by searching a standard reference database, by contemporaneously analyzing mass spectra from reference standards, and by de novo interpretation. We identified a total of 271 compounds belonging to 24 classes; all compounds but 1 were halogenated. Anthropogenic contaminants and halogenated natural products were concurrently detected. A total of 86 compounds were anthropogenic contaminants that are not routinely targeted in environmental surveys, and 54 compounds were halogenated natural products. A total of 112 spectra were identified de novo, demonstrating that exclusive reliance on commercially available reference standards and mass spectral libraries may miss a significant fraction of identifiable compounds. We also cataloged 27 halogenated mass spectra that were not able to be identified. Due to the volume and complexity of the identification data, we developed custom software to organize and provide shared access to the identified mass spectra and related information. The nontargeted analytical method and data reporting system, in combination with the analysis of a high-trophic-level sentinel species, demonstrates a framework for creating an inventory of persistent and bioaccumulative contaminants in marine environments, with the future goal of suggesting new compounds for further investigation by targeted monitoring and risk assessment.

Pyrethroids in Southern California coastal sediments

Little is known about pyrethroid fate and effects in estuarine and marine environments. In the present study, the extent and magnitude of pyrethroids in coastal embayments of the Southern California Bight (SCB), USA, were assessed. Using a stratified probabilistic design, 155 sediment samples were collected from four embayment habitats (estuaries, marinas, open bays, and ports) and analyzed for eight common-use pyrethroids. Total pyrethroid concentrations ranged from less than 0.5 to 230 µg/kg dry weight (area-weighted mean concentration=5.1 ± 3.1 µg/kg) and were detected in 35% of the total SCB embayment area. Estuaries and marinas had the greatest areal extent of detectable concentrations (up to 65%) and the greatest area-weighted mean concentrations (22.1 ± 26.5 µg/kg). Sites with the greatest pyrethroid concentrations were located near sources of runoff from urban watersheds. Bifenthrin and cyfluthrin were detected in 32 and 15% of all samples, respectively, whereas the other six pyrethroids were detected in ≤ 5% of samples. Permethrin and bifenthrin had the highest concentrations at 132 and 65 µg/kg. Toxic units estimated for the marine amphipod Eohaustorius estuarius ranged from 0 to 5.8, exceeding unity in 9 and 32% of the total and estuary habitat areas, respectively, and were not correlated with mortality, suggesting that other factors (e.g., co-occurring contaminants, reduced bioavailability) may affect the predictive capability using a single test species.

China's water pollution by persistent organic pollutants

Available data were reviewed to assess the status of contamination by persistent organic pollutants (POPs), including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), in drinking water sources and coastal waters of China. The levels of POPs in China's waters were generally at the high end of the global range. A comparison of China's regulatory limits indicated that PCBs in rivers and coastal water may pose potential human health risk. Occurrence of DDTs in some rivers of China may also pose health risk to humans using the regulatory limits of DDTs recommended by the European Union. Future monitoring of POPs in China's waters should be directed towards analytes of concern (e.g. PCBs and PCDD/Fs) and to fill data gaps for analytes (e.g. PBDEs, PCDD/Fs, and chlordane) and in watersheds/regions (e.g. West China) where data are scarce.

Enantioselectivity of polychlorinated biphenyl atropisomers in sediment and biota from the Turtle/Brunswick River estuary, Georgia, USA

To investigate the potential for enantioselective transformation and accumulation, the enantiomer distributions of seven polychlorinated biphenyl (PCB) atropisomers were measured in the sediment and biota from a sub-tropical estuary heavily contaminated with Aroclor 1268, a technical mixture of highly chlorinated PCB congeners. Enantiomer fractions (EFs) of PCBs 91, 95, 136, 149, 174, 176, and 183 in marsh sediment, invertebrate, forage and predatory fish species, and bottlenose dolphins were determined. Non-racemic EFs greater than 0.75 were found in sediments for PCBs 136 and 174, likely the result of microbial dechlorination. Although enantiomer fractions in grass shrimp (Palaemonetes spp.) mirrored those of sediment, fish species had EFs that differed significantly from sediment or grass shrimp. Similarly, bottlenose dolphins were also found to contain non-racemic quantities of PCBs 91, 136, 174, 176, and 183. Non-racemic EFs in these biota were likely a result of both uptake of non-racemic proportions of PCBs from the diet and enantioselective biotransformation.

Analysis, occurrence, and toxic potential of pyrethroids, and fipronil in sediments from an urban estuary

Eight pyrethroids and fipronil and its three major degradates were analyzed in urban estuarine sediments that exhibited a range of toxic effects to an amphipod test species. Sediments from Ballona Creek, an urban estuary in Southern California (USA), collected during three dry season events were analyzed by gas chromatography with electron capture and negative chemical ionization mass spectrometric detection (GC-ECD and GC-NCI-MS). The two detection methods were in agreement for intermediate levels of pyrethroid contamination (10-50 ng/g dry wt) but deviated for both low and high concentrations (< 5 and > 50 ng/g). Sediments contained total pyrethroids as high as 473 ng/g with permethrin, bifenthrin, and cypermethrin as the most abundant compounds. In contrast, fipronil and its desulfinyl, sulfide, and sulfone degradates were detected at much lower levels (<or= 0.18-16 ng/g). Toxic units estimated for these compounds revealed that bifenthrin and cypermethrin were likely contributors to the mortality observed in tests with the estuarine amphipod Eohaustorius estuarius. Although fipronil was not a likely contributor to the observed mortality, the concentrations detected may be of concern for more sensitive crustacean species. Furthermore, the spatial pattern of pyrethroid contamination and potential toxicity was highly correlated with fine-grained substrate, which shifted to downstream stations within a three-month period during the dry season.

Exchange of polycyclic aromatic hydrocarbons among the atmosphere, water, and sediment in coastal embayments of southern California, USA

The present study investigated cross-media transport between both the sediment and the water column and between the water column and the atmosphere, to understand the role of each compartment as a source or a sink of polycyclic aromatic hydrocarbons (PAH) in southern California, USA, coastal waters. Concentrations of PAH were measured in the atmosphere, water column, and sediment at four water-quality-impaired sites in southern California: Ballona Creek Estuary, Los Angeles Harbor, Upper Newport Bay, and San Diego Bay. These concentrations were used to calculate site-specific sediment-water and atmosphere-water exchange fluxes. The net sediment-water exchange of total PAH (t-PAH) was positive, indicating that sediments were a source to the overlying water column. Furthermore, the net atmosphere-water exchange (gas exchange + dry particle deposition) of t-PAH was typically positive also, indicating the water column was a net source of PAH to the surrounding atmosphere through gas exchange. However, in all cases, the magnitude of the diffusive flux of PAH out of the sediments and into the water column far exceeded input or output of PAH through air/water exchange processes. These results demonstrate the potential importance of contaminated sediments as a source of PAH to the water column in coastal waters of southern California.

Polybrominated diphenyl ethers in pinnipeds stranded along the southern California coast

Little to no information exists for polybrominated diphenyl ethers (PBDEs) in marine mammals frequenting the highly urbanized southern California (USA) coast. Fourteen PBDE congeners were determined by GC-ECNI-MS in blubber of pinnipeds stranded locally between 1994 and 2006. Total PBDE concentrations (SigmaPBDE) in California sea lion (n = 63) ranged from 0.04 to 33.7 microg/g wet weight (mean: 5.24 microg/g). To our knowledge, these are the highest reported PBDE levels in marine mammals to date. By comparison, mean SigmaPBDE in Pacific harbor seals (n = 9) and northern elephant seals (n = 16) were 0.96 and 0.09 microg/g, respectively. PBDEs in adult males were higher than for adult females, however, no age class differences or temporal trends were observed. As the first PBDE data reported for marine mammals in this region, the elevated levels underscore the need for additional studies on the sources, temporal trends, and potential effects of PBDEs in highly urbanized coastal zones.

Persistent organochlorine pollutants and toxaphene congener profiles in bottlenose dolphins (Tursiops truncatus) frequenting the Turtle/Brunswick River Estuary (TBRE) in coastal Georgia, USA

Although the Turtle/Brunswick River Estuary (TBRE) in coastal Georgia (USA) is severely contaminated by persistent organochlorine pollutants (POPs), little information regarding POPs in higher-trophic-level biota in this system is available. In the present study, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs; including DDTs, chlordanes, and mirex), and chlorinated monoterpenes (toxaphene) were measured using gas chromatography with electron-capture detection and gas chromatography with electron-capture negative ion mass spectrometry (GC-ECNI-MS) in blubber of free-ranging and stranded bottlenose dolphins (Tursiops truncatus). Mean total PCBs (78.6 +/- 32.4 microg/g lipid) and toxaphene (11.7 +/- 9.3 microg/g lipid) were significantly higher in dolphins sampled in the TBRE than in dolphins stranded near Savannah (GA, USA) 80 to 100 km to the north. Levels of OCPs were several-fold lower than levels of PCBs; moreover, PCBs comprised 81 and 67% of the total POP burden in TBRE and non-TBRE dolphins, respectively. Analyses with GC-ECNI-MS revealed that 2,2,5-endo,6-exo,8,8,9,10-octachlorobornane (P-42a), a major component in technical toxaphene and a major residue congener in local estuarine fish species, was the most abundant chlorobornane in both sets of blubber samples. Mean total POP concentrations (sum of PCBs, OCPs, and toxaphene) approached 100 microg/g lipid for the TBRE animals, well above published total PCB thresholds at which immunosuppresion and/or reproductive anomalies are thought to occur. These results indicate extended utilization of the highly contaminated TBRE as habitat for a group of coastal estuarine dolphins, and they further suggest that these animals may be at risk because of elevated POP concentrations.

A passive sampler based on solid-phase microextraction for quantifying hydrophobic organic contaminants in sediment pore water

Sediment-quality assessment often is hindered by the lack of agreement between chemical and biological lines of evidence. One limitation is that the bulk sediment toxicant concentration, the most widely used chemical parameter, does not always represent the bioavailable concentration, particularly for hydrophobic organic compounds (HOCs) in highly contaminated sediments. In the present study, we developed and tested a pore-water sampler that uses solid-phase microextraction (SPME) to measure freely dissolved (bioavailable) HOC concentrations. A single polydimethylsiloxane (PDMS)-coated SPME fiber is secured in a compact, protective housing that allows aqueous exchange with whole sediment while eliminating direct contact with sediment particles. Fibers with three PDMS coating thicknesses were first calibrated for 12 model HOCs of current regulatory concern. Precalibrated samplers were exposed to spiked estuarine sediment in laboratory microcosms to determine the time to equilibrium and the equilibrium concentrations across a range of sediment contamination. Time to equilibrium ranged from 14 to 110 d, with 30 d being sufficient for more than half the target HOCs. Equilibrium SPME measurements, ranging from 0.009 to 2,400 ng/L, were highly correlated with but, in general, lower than HOC pore-water concentrations determined independently by liquid-liquid extraction. This concept shows promise for directly measuring the freely dissolved concentration of HOCs in sediment pore water, a previously difficult-to-measure parameter that will improve our ability to assess the impacts of contaminated sediments.