Steven M. Bay

Contaminants of emerging concern in municipal wastewater effluents and marine receiving water

The occurrence and concentrations of contaminants of emerging concern (CECs) were investigated in municipal effluents and in marine receiving water. Final effluent from four large publicly owned treatment works (POTWs) and seawater collected near the respective POTW outfall discharges and a reference station were collected quarterly over one year and analyzed for 56 CECs. Several CECs were detected in effluents; naproxen, gemfibrozil, atenolol, and tris(1-chloro-2-propyl)phosphate were the compounds most frequently found and with the highest concentrations (>1 µg/L). Gemfibrozil and naproxen had the highest seawater concentrations (0.0009 and 0.0007 µg/L) and also were among the most frequently detected compounds. Effluent dilution factors ranged from >400 to approximately 1,000. Fewer CECs were detected and at lower concentrations in seawater collected from the reference station than at the outfall sites. Effluent concentrations for some CECs (e.g., pharmaceuticals) were inversely related to the degree of wastewater treatment. This trend was not found in seawater samples. Few temporal differences were observed in effluent or seawater samples. Effluent CEC concentrations were lower than those currently known for chronic toxicity thresholds. Nevertheless, the evaluation of potential chronic effects for CECs is uncertain because aquatic life toxicity thresholds have been developed for only a few CECs, and the effluent and seawater samples had compounds, such as nonylphenol, known to bioaccumulate in local fish. Additional data are needed to better understand the significance of CEC presence and concentrations in marine environments.

Water quality impacts of stormwater discharges to Santa Monica Bay

Urban stormwater runoff is a major source of contaminants to southern Californias coastal waters, yet little is known about the fate and effects of these discharges. A 3-year multidisciplinary project was conducted to investigate the dispersion of stormwater plumes in Santa Monica Bay and the resultant impacts on the water column and benthos. This paper describes the toxicity component of the study. Sea urchin fertilization toxicity tests were conducted on stormwater from the two largest discharges into the bay: Ballona Creek, which drains a highly urbanized watershed, and Malibu Creek, which receives runoff from a largely undeveloped watershed. Every sample of Ballona Creek stormwater tested was toxic (usually >5 toxic units), while Malibu Creek stormwater had a lower frequency and magnitude of toxicity (usually <4 toxic units). Surface water samples collected within the Ballona Creek stormwater discharge plume were always toxic whenever the concentration of stormwater in the plume exceeded 10%. The toxic portion of the Ballona Creek stormwater plume extended more than 4 km offshore on one occasion. Toxicity identification studies indicated that zinc was the primary cause of toxicity in both Ballona Creek stormwater and the discharge plume. No acute sediment toxicity (10-day amphipod survival) was present in the study area, although interstitial water toxicity was present at some stations located near the mouth of Ballona Creek. Differences in watershed characteristics likely were responsible for the greater toxicity of the Ballona Creek stormwater discharge plume. The Ballona Creek watershed contained a greater degree of urbanization (83% versus 12% for Malibu Creek) and the presence of a network of concrete flood control channels resulted in a stormwater plume containing elevated concentrations of toxins that received less initial dilution (compared to Malibu Creek) in the nearshore environment.

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.

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.

Analysis of Endocrine Disruption in Southern California Coastal Fish Using an Aquatic Multispecies Microarray

Background Endocrine disruptors include plasticizers, pesticides, detergents, and pharmaceuticals. Turbot and other flatfish are used to characterize the presence of chemicals in the marine environment. Unfortunately, there are relatively few genes of turbot and other flatfish in GenBank, which limits the use of molecular tools such as microarrays and quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) to study disruption of endocrine responses in sentinel fish captured by regulatory agencies. Objectives We fabricated a multigene cross-species microarray as a diagnostic tool to screen the effects of environmental chemicals in fish, for which there is minimal genomic information. The array included genes that are involved in the actions of adrenal and sex steroids, thyroid hormone, and xenobiotic responses. This microarray will provide a sensitive tool for screening for the presence of chemicals with adverse effects on endocrine responses in coastal fish species. Methods We used a custom multispecies microarray to study gene expression in wild hornyhead turbot (Pleuronichthys verticalis) collected from polluted and clean coastal waters and in laboratory male zebrafish (Danio rerio) after exposure to estradiol and 4-nonylphenol. We measured gene-specific expression in turbot liver by qRT-PCR and correlated it to microarray data. Results Microarray and qRT-PCR analyses of livers from turbot collected from polluted areas revealed altered gene expression profiles compared with those from nonaffected areas. Conclusions The agreement between the array data and qRT-PCR analyses validates this multispecies microarray. The microarray measurement of gene expression in zebrafish, which are phylogenetically distant from turbot, indicates that this multispecies microarray will be useful for measuring endocrine responses in other fish.

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.

Impacts of stormwater discharges on the nearshore benthic environment of Santa Monica Bay.

Although large loads of potentially toxic constituents are discharged from coastal urban watersheds, very little is known about the fates and eventual impacts of these stormwater inputs once they enter the ocean. The goal of this study was to examine the effects of stormwater discharges on the benthic marine environment of Santa Monica Bay. Sediment samples were collected across a gradient of stormwater impact following significantly sized storm events offshore Ballona Creek (a predominantly developed watershed) and Malibu Creek (a predominantly undeveloped watershed). Sediments offshore Malibu Creek had a greater proportion of fine-grained sediments, organic carbon, and naturally occurring metals (i.e., aluminum and iron), whereas sediments offshore Ballona Creek had higher concentrations of anthropogenic metals (i.e., lead) and organic pollutants (i.e., total DDT, total PCB, total PAH). The accumulation of anthropogenic sediment contaminants offshore Ballona Creek was evident up to 2 km downcoast and 4 km upcoast from the creek mouth and sediment concentrations covaried with distance from the discharge. Although changes in sediment texture, organic content, and an increase in sediment contamination were observed, there was little or no alteration to the benthic communities offshore either Ballona or Malibu Creek. Both sites were characterized as having an abundance, species richness, biodiversity and benthic response index similar to shallow water areas distant from creek mouths throughout the Southern California Bight. There was not a preponderance of pollution tolerant, nor a lack or pollution sensitive, species offshore either creek mouth.

Temporal and spatial distributions of contaminants in sediments of Santa Monica Bay, California

Contaminant inputs from wastewater discharge, a major source of contamination to Santa Monica Bay (SMB), have declined drastically during the last three decades as a result of improved treatment processes and better source control. To assess the concomitant temporal changes in the SMB sediments, a study was initiated in June 1997, in which 25 box cores were collected using a stratified random sampling design. Five sediment strata corresponding to the time intervals of 1890-1920, 1932-1963, 1965-1979, 1979-1989, and 1989-1997 were identified using (210)Pb dating techniques. Samples from each stratum were analyzed for metals, 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites (DDTs), polychlorinated biphenyls (PCBs), and total organic carbon (TOC). Samples from the 1965-1979, 1979-1989, and 1989-1997 strata were also analyzed for polycyclic aromatic hydrocarbons (PAHs) and linear alkylbenzenes (LABs). Sediment metal concentrations increased from 1890-1979 and were similar during the time intervals of 1965-1979, 1979-1989, and 1989-1997, although the mass emissions of trace metals from sewage inputs declined substantially during the same time period. Trace organic contamination in SMB was generally highest in sediments corresponding to deposition during the years of 1965-1979 or 1979-1989 and showed a decline in concentration in the 1989-1997 stratum. Temporal trends of contamination were greatest in sediments collected from areas near the Hyperion Treatment Plant (HTP) outfall system and on the slope of Redondo Canyon. The highest contaminant concentrations were present in sediments near the HTP 7-mile outfall in the 1965-1979 stratum. Elevated trace metal and organic concentrations were still present in the 1989-1997 stratum of most stations, suggesting that sediment contaminants have moved vertically in the sediment column since sludge discharges from the 7-mile outfall (a dominant source of contamination to the bay) ceased in 1987. The widespread distributions of DDTs and PCBs in SMB and highly confined distribution of LABs around the HTP outfall system were indicative of a dispersal mechanism remobilizing historically deposited contaminants to areas relatively remote from the point of discharge.

Spatial scales and evolution of stormwater plumes in Santa Monica Bay

Rainfall during winter storms produces extensive turbid, freshwater plumes in the coastal waters of the Southern California Bight. When the plumes result from urban runoff they contain toxic pollutants along with pathogenic bacteria and viruses, often resulting in closure of public beaches. We examined the spatial structure and evolution of stormwater plumes in Santa Monica Bay in 1996. The plumes resulted from freshwater discharge from the Ballona Creek and Malibu Creek watersheds which supply approximately 60% of the freshwater runoff to Santa Monica Bay. The spatial scales of the plumes were determined using shipboard measurements of water properties obtained from towyo transects and surface underway sampling. Salinity maps showed that the plumes typically extended 4-7 km offshore, consistent with scaling by the internal Rossby radius of deformation. Plumes extended along shore 10 km or more. Generally the plumes occupied the upper 10 m of the water column. The persistence time of a plume offshore of Ballona Creek was about three days based on a sequence of surveys in March 1996 following rainfall of about 21 mm. Limited comparison of plumes from Ballona Creek, which drains a developed watershed, and Malibu Creek, which drains a rural watershed, suggested that Malibu Creek required greater rainfall to produce an offshore plume. A stormwater plume offshore of Malibu Creek was observed on both sides of the creek mouth, possibly due to freshwater discharge from smaller surrounding watersheds or advection of freshwater discharges from the east and south. Plumes offshore of Ballona Creek mainly resulted from the creek itself and usually extended northward from the creek mouth, consistent with the wind forcing and the Coriolis acceleration.

Framework for interpreting sediment quality triad data

Integration of multiple lines of evidence (MLOE) data in a sediment quality triad assessment can be accomplished by means of numerous approaches, with most relying on some form of expert best professional judgment. Best professional judgment (BPJ) can be problematic in application to large data sets or in a regulatory setting where the assessment protocol needs to be transparent and consistently reproducible. We present a quantitative, objective framework for integrating the results of triad-based assessments and test its efficacy by applying it to 25 California sites and comparing the resulting classifications with those of 6 experts who were provided the same data. The framework is based on integrating the answers to 2 questions: 1) is there biological degradation, and 2) is chemical exposure high enough to potentially result in a biological response? The framework produced results that matched the median classifications of the experts better than did 5 of the 6 experts. Moreover, the framework was unbiased, with samples that differed from the median expert response evenly divided between those classified as more or less impacted. The framework was also evaluated by application to a set of sites from known degraded and reference areas, which the framework distinguished well. Although any framework needs to be flexible to supplemental data when they are available, the framework presented provides an objective means for using a triad-based approach in large-scale assessments for which relying on expert input for every sample is impractical.