Severe Coal Tar Sealcoat Runoff Toxicity to Fish Is Prevented by Bioretention Filtration

Structure-activity relationships for alkyl-phenanthrenes support two independent but interacting synergistic models for PAC mixture potency

Multiple lines of evidence at whole animal, cellular and molecular levels implicate polycyclic aromatic compounds (PACs) with three rings as drivers of crude oil toxicity to developing fish. Phenanthrene (P0) and its alkylated homologs (C1- through C4-phenanthrenes) comprise the most prominent subfraction of tricyclic PACs in crude oils. Among this family, P0 has been studied intensively, with more limited detail available for the C4-phenanthrene 1-methyl-7-isopropyl-phenanthrene (1-M,7-IP, or retene). While both compounds are cardiotoxic, P0 impacts embryonic cardiac function and development through direct blockade of K+ and Ca2+ currents that regulate cardiomyocyte contractions. In contrast, 1-M,7-IP dysregulates aryl hydrocarbon receptor (AHR) activation in developing ventricular cardiomyocytes. Although no other compounds have been assessed in detail across the larger family of alkylated phenanthrenes, increasing alkylation might be expected to shift phenanthrene family member activity from K+/Ca2+ ion current blockade to AHR activation. Using embryos of two distantly related fish species, zebrafish and Atlantic haddock, we tested 14 alkyl-phenanthrenes in both acute and latent developmental cardiotoxicity assays. All compounds were cardiotoxic, and effects were resolved into impacts on multiple, highly specific aspects of heart development or function. Craniofacial defects were clearly linked to developmental cardiotoxicity. Based on these findings, we suggest a novel framework to delineate the developmental toxicity of petrogenic PAC mixtures in fish, which incorporates multi-mechanistic pathways that produce interactive synergism at the organ level. In addition, relationships among measured embryo tissue concentrations, cytochrome P4501A mRNA induction, and cardiotoxic responses suggest a two-compartment toxicokinetic model that independently predicts high potency of PAC mixtures through classical metabolic synergism. These two modes of synergism, specific to the sub-fraction of phenanthrenes, are sufficient to explain the high embryotoxic potency of crude oils, independent of as-yet unmeasured compounds in these complex environmental mixtures.

A critical review of the mechanisms, factors, and performance of pervious concrete to remove contaminants from stormwater runoff

Stormwater can carry pollutants accumulated on impervious surfaces in urban areas into natural water bodies in absence of stormwater quality improvement devices. Pervious concrete (PC) pavement is one of the low-impact development practices introduced for urban flooding prevention and stormwater pollution reduction. PC removes various types of water contaminants. Mechanisms contributing to the water pollution removal capacity of PC can be categorized into three groups: physical, chemical, and biological. Properties of PC such as permeability, porosity, thickness, and adsorption capacity influence removal of all contaminants, although their impact might differ depending on the pollutant properties. Chemical mechanisms include precipitation, co-precipitation, ion and ligand exchange, complexation, diffusion, and sorption. Bulk organics and nutrients are removed primarily by biodegradation. Physical filtration is the primary mechanism to retain suspended solids, although biological activities may have a minor contribution. Release of calcium (Ca2+) and hydroxide (OH-) from hardened cement elevates the effluent pH, which is an environmental concern. However, the pH elevation is also the prime contributor to heavy metals and nutrients removal through precipitation. Specific cementitious materials (e.g., Pozzolans and nanoparticles) and carbonation curing approach are recommended to control effluent pH elevation. Complexation, diffusion, ion solubility, and stability constants are other mechanisms and parameters that influence heavy metal removal. Organic matter availability, electrostatic attraction, temperature, pH, contact time, specific surface area, and roughness of PC pores contribute to the pathogen removal process. Although PC has been found promising in removing various water pollutants, limited salinity removal can be achieved due to the inherent release of Ca2+and OH- from PC.

Mitigating tire wear particles and tire additive chemicals in stormwater with permeable pavements

6PPD-quinone (6PPDQ) is a recently discovered chemical that is acutely toxic to coho salmon (Oncorhynchus kisutch) and can form via environmental exposure of 6PPD, a compound found extensively in tire wear particles (TWPs). TWPs deposited on roads are transported to aquatic ecosystems via stormwater, contributing to microplastic pollution and organic contaminant loads. However, little is known about the fate of TWPs and their leachable contaminants in these systems. We conducted three experiments at a high school in Tacoma, Washington, to quantify the treatment performance of permeable pavement (PP) formulations, a type of green stormwater infrastructure (GSI), for TWPs and ten tire-associated contaminants, including 6PPDQ. The PPs comprised concrete and asphalt, with and without cured carbon fibers, to improve the mechanical properties of PPs. Pavements were artificially dosed and had underdrains to capture effluent. Three experiments were conducted to evaluate PP mitigation of tire-associated pollution using cryomilled tire particles (cTPs). The 1st and 3rd experiments established a baseline for TWPs and contaminants and assessed the potential for continued pollutant release. During experiment 2, cTPs were applied to each pavement. Our results showed that the PPs attenuated >96 % of the deposited cTPs mass. An estimated 52-100 % of potentially leachable 6PPDQ was removed by the PP systems between the influent and effluent sampling stations. Background 6PPDQ concentrations in effluents ranged from 0 to 0.0029 μg/L. Effluent 6PPDQ concentrations were not explained by effluent TWP concentrations in experiments 1 or 2 but were significantly correlated in experiment 3, suggesting that leaching of 6PPDQ from TWPs retained in the pavement was minimal during a subsequent storm. Our results suggest that PPs may be an effective form of GSI for mitigating tire-associated stormwater pollution. The improved strength offered by cured carbon fiber-amended pavements extends PP deployment on high-traffic roadways where tire-associated pollution poses the greatest environmental risk.

Bioretention filtration prevents acute mortality and reduces chronic toxicity for early life stage coho salmon (Oncorhynchus kisutch) episodically exposed to urban stormwater runoff

As the human population of western North America continues to expand, widespread patterns of urban growth pose increasingly existential threats to certain wild stocks of Pacific salmon and steelhead (Oncorhynchus sp.). Rainfall previously absorbed into the soils of forests and grasslands falls instead on pavement and other hardened surfaces. This creates stormwater runoff that carries toxic metals, oil, and many other contaminants into salmon-bearing habitats. These include freshwater streams where coho salmon (O. kisutch) spawn in gravel beds. Coho salmon embryos develop within a thick eggshell (chorion) for weeks to months before hatching as alevins and ultimately emerging from the gravel as fry. Untreated urban runoff is highly toxic to older coho salmon (freshwater-resident juveniles and adult spawners), but the vulnerability of the earliest life stages remains poorly understood. To address this uncertainty, we fertilized eggs and raised them under an episodic stormwater exposure regimen, using runoff collected from a high-traffic arterial roadway from 15 discrete storm events. We monitored survival and morphological development, as well as molecular markers for contaminant exposure and cardiovascular stress. We also evaluated the benefit of treating runoff with green infrastructure (bioretention filtration) on coho salmon health and survival. Untreated runoff caused subtle sublethal toxicity in pre-hatch embryos with no mortality, followed by high rates of mortality from exposure at hatch. Bioretention filtration removed most measured contaminants (bacteria, dissolved metals, and polycyclic aromatic hydrocarbons), and the treated effluent was considerably less toxic - notably preventing mortality at the alevin stage. Our findings indicate that untreated urban runoff poses an important threat to early life stage coho salmon, in terms of both acute and delayed-in-time mortality. Moreover, while inexpensive management strategies involving bioinfiltration are promising, future green infrastructure effectiveness research should emphasize sublethal metrics for contaminant exposure and adverse health outcomes in salmonids.

Biochar and fungi as bioretention amendments for bacteria and PAH removal from stormwater

Bioretention has been widely used to mitigate hydrologic impacts of stormwater runoff and is increasingly being relied upon to treat chemical and biological pollutants transported by stormwater. Despite this reliance, we still lack an understanding of treatment performance for certain organic and biological contaminants which may interact with biotic and abiotic components of bioretention systems. We evaluated the treatment of fecal indicator bacteria (FIB) and polycyclic aromatic hydrocarbons (PAHs) in stormwater runoff by bioretention. We compared treatment performance by Washington's standard bioretention mix of 60% sand: 40% compost (by volume), and by three other mixtures amended with biochar, fungi (Stropharia rugosoannulata), or both. All bioretention columns were conditioned with clean water and then dosed with collected roadway runoff at a rate equivalent to a 6 month, 24 h storm in this region during 8 events over a 14-month period. Effluents for each column were analyzed for 23 PAHs, Escherichia coli, fecal coliform, dissolved organic carbon (DOC), and total suspended solids (TSS). The fate and transport of PAHs within the bioretention columns was tracked by measuring soil PAHs in media cores taken from the columns. ΣPAH were almost completely removed by all treatments across all storms, with removal rates ranging from 97 to 100% for 94 out of 96 samples. Compost appeared to be a source of PAHs in bioretention media, as biochar-amended media initially contained half the ΣPAHs as treatments with the standard 60:40 sand:compost mixture. We observed a net loss of ΣPAHs (19-73%) in bioretention media across the study, which could not be explained by PAHs in the effluent, suggesting that bioremediation by microbes and/or plants attenuated media PAHs. E. coli and fecal coliform were exported in the first dosing event, but all columns achieved some treatment in subsequent dosing events. Overall, these findings suggest that PAHs in stormwater can be remediated with bioretention, are unlikely to accumulate in bioretention media, and that biochar amendments can improve the treatment of E. coli.

Effects of substances released from a coal tar-based coating used to protect harbor structures on oysters

Products coal tar-based are largely used as concrete structures as protective coatings but some questions about leaching and potential toxic effects remain unclear. A laboratory experiment exposing oysters to miniaturized concrete pillars painted with Lackpoxi N1761 over time was performed and trace elements and 17 PAH were monitored in seawater exposure media, and oyster tissues. The original paint composition was also analyzed, and high concentrations of trace elements and PAH were detected. Sharp increases in PAH concentrations were observed after 6-96 h in exposure media and oyster tissues, suggesting that these compounds were leached from the painted structures. In parallel, the integrity of the hemocytes lysosomal membranes of exposed organisms has been damaged. Based on the response of this biomarker, the use of Lackpoxi N1761 is potentially harmful to the environment and it is required that coal tar-based paints be evaluated according to the environmental risk assessment protocols.

Prioritizing conservation actions in urbanizing landscapes

Urbanization-driven landscape changes are harmful to many species. Negative effects can be mitigated through habitat preservation and restoration, but it is often difficult to prioritize these conservation actions. This is due, in part, to the scarcity of species response data, which limit the predictive accuracy of modeling to estimate critical thresholds for biological decline and recovery. To address these challenges, we quantify effort required for restoration, in combination with a clear conservation objective and associated metric (e.g., habitat for focal organisms). We develop and apply this framework to coho salmon (Oncorhynchus kisutch), a highly migratory and culturally iconic species in western North America that is particularly sensitive to urbanization. We examine how uncertainty in biological parameters may alter locations prioritized for conservation action and compare this to the effect of shifting to a different conservation metric (e.g., a different focal salmon species). Our approach prioritized suburban areas (those with intermediate urbanization effects) for preservation and restoration action to benefit coho. We found that prioritization was most sensitive to the selected metric, rather than the level of uncertainty or critical threshold values. Our analyses highlight the importance of identifying metrics that are well-aligned with intended outcomes.

Amino, nitro, chloro, hydroxyl and methyl substitutions may inhibit the binding of PAHs with DNA

The binding of PAHs with DNA to form PAH-DNA adducts is a crucial step in PAH-induced carcinogenesis. How functional groups affect this binding is largely unknown. Here, we observed that functional group substitutions strongly inhibited PAH-DNA binding. Additionally, -OH substitution has the most potent inhibitory effect as it causes the smallest change in the electrostatic surface potential. Fourier transform infrared spectroscopy and molecular docking analyses demonstrated that PAH derivatives bind with guanine via intercalation and groove binding and then non-specifically insert into the major/minor grooves of DNA. Quantum chemical calculations suggested that hydrogen/halogen bonding may be essential in affecting the binding of functional group-substituted PAHs with DNA. It was further revealed that Log K_OA and the PAH derivatives' melting points correlated significantly with binding affinity, implying that changes in the physicochemical characteristics are important factors. This study opens a new window for understanding the relationship between highly toxic PAH derivatives and genetic materials.

Urban stormwater and crude oil injury pathways converge on the developing heart of a shore-spawning marine forage fish

Understanding how aquatic organisms respond to complex chemical mixtures remains one of the foremost challenges in modern ecotoxicology. Although oil spills are typically high-profile disasters that release hundreds or thousands of chemicals into the environment, there is growing evidence for a common adverse outcome pathway (AOP) for the vulnerable embryos and larvae of fish species that spawn in oiled habitats. Molecular initiating events involve the disruption of excitation-contraction coupling in individual cardiomyocytes, which then dysregulate the form and function of the embryonic heart. Phenanthrenes and other three-ring (tricyclic) polycyclic aromatic hydrocarbons (PAHs) are key drivers for this developmental cardiotoxicity and are also relatively enriched in land-based urban runoff. Similar to oil spills, stormwater discharged from roadways and other high-traffic impervious surfaces contains myriad contaminants, many of which are uncharacterized in terms of their chemical identity and toxicity to aquatic organisms. Nevertheless, given the exceptional sensitivity of the developing heart to tricyclic PAHs and the ubiquitous presence of these compounds in road runoff, cardiotoxicity may also be a dominant aspect of the stormwater-induced injury phenotype in fish early life stages. Here we assessed the effects of traffic-related runoff on the embryos and early larvae of Pacific herring (Clupea pallasii), a marine forage fish that spawns along the coastline of western North America. We used the well-characterized central features of the oil toxicity AOP for herring embryos as benchmarks for a detailed analysis of embryolarval cardiotoxicity across a dilution gradient ranging from 12 to 50% stormwater diluted in clean seawater. These injury indicators included measures of circulatory function, ventricular area, heart chamber looping, and the contractility of both the atrium and the ventricle. We also determined tissue concentrations of phenanthrenes and other PAHs in herring embryos. We find that tricyclic PAHs are readily bioavailable during cardiogenesis, and that stormwater-induced toxicity is in many respects indistinguishable from canonical crude oil toxicity. Given the chemical complexity of urban runoff, non-tricyclic PAH-mediated mechanisms of developmental toxicity in fish remain likely. However, from the standpoint of managing wild herring populations, our results suggest that stormwater-driven threats to individual survival (both near-term and delayed mortality) can be understood from decades of past research on crude oil toxicity. Moreover, Pacific herring embryos are promising sentinels for water quality monitoring in nearshore marine habitats, as in situand sensitive indicators of both toxic runoff and the effectiveness of pollution reduction efforts such as green stormwater infrastructure.

A Review of the Literature on Potential Effects of Runoff from Refined Coal-Tar-Based Sealant Coating on Aquatic Organisms

Pavement sealants are frequently applied to parking lots and driveways to improve their appearance and protect the integrity of the underlying asphalt. We performed a comprehensive literature review to summarize the potential impacts of refined coal-tar-based sealant (RCTS) runoff to aquatic organisms and to evaluate the strengths and weaknesses of the lines of evidence presented in the literature. The studies reviewed included both laboratory and field exposures, with and without exposure to UV light, and measured effects on multiple endpoints associated with bacteria, benthic macroinvertebrates, and fish. Several studies demonstrated that constituents in RCTS runoff can affect survival, growth, behavior, development, and molecular responses of aquatic organisms in controlled laboratory settings. However, translating effects observed in the laboratory to field settings, where runoff is diluted and constituents interact with particulate and dissolved stream constituents (e.g., organic matter), has proven difficult. In this review, we identify the strengths and weaknesses of the existing literature and provide recommendations for study designs and methods to fill the most critical data gaps in understanding the risk of this material to aquatic organisms. Our review highlights the need for environmentally relevant study designs that demonstrate cause-effect relationships under field conditions. Integr Environ Assess Manag 2019;00:1-11. © 2019 SETAC.

Quantification of azaarenes, hydroxylated azaarene derivatives, and other polar compounds released in urban runoff from two commercial sealcoat products

Sealcoat is an emulsified coating product applied to asphalt to protect against surface weathering. Sealcoat products contain coal-tar (CT) or petroleum-derived residues and are a recognized source of polycyclic aromatic hydrocarbons (PAHs) in urban areas. Although the toxicity of urban runoff from CT-sealed asphalt is established, chemical characterization has focused more on PAHs and alkylated derivatives and less on polar transformation products. In this study, solid-phase extraction (SPE) was used to concentrate dissolved (<0.2 μm) species in runoff collected from asphalt surfaces sealed with CT pitch or steam-cracked petroleum (SCP) residues. CT-sealed surfaces released a 20-fold greater concentration of SPE-extractable compounds in runoff compared to SCP-sealed surfaces. Representative compounds were sorted into four groups: nitrogen heterocycles (azaarenes) and other oxygen- and sulfur-containing species (N HET); hydroxylated N heterocycles (hydroxylated N HET); the nonionic surfactant 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD); and styrene-acrylonitrile polymer byproducts (SAN Trimer). Species concentrations and weathering-related disappearance behavior differed among the four subgroups. While hydroxylated N HET concentrations decreased by 94% in runoff from CT-sealed surfaces 60 h after sealcoat application, SAN Trimer concentrations in CT and SCP runoff increased over time as polymerization progressed, illustrating the complex changes the chemicals in sealcoat undergo as it cures under environmentally-relevant conditions. Overall, this study shows that urban runoff collected from CT-sealed and SCP-sealed asphalt surfaces is a potential source of water-soluble contaminants with unknown long-term ecotoxicological effects to aquatic systems.

Urban stormwater runoff negatively impacts lateral line development in larval zebrafish and salmon embryos

After a storm, water often runs off of impervious urban surfaces directly into aquatic ecosystems. This stormwater runoff is a cocktail of toxicants that have serious effects on the ecological integrity of aquatic habitats. Zebrafish that develop in stormwater runoff suffer from cardiovascular toxicity and impaired growth, but the effects of stormwater on fish sensory systems are not understood. Our study investigated the effect of stormwater on hair cells of the lateral line in larval zebrafish and coho salmon. Our results showed that although toxicants in stormwater did not kill zebrafish hair cells, these cells did experience damage. Zebrafish developing in stormwater also experienced impaired growth, fewer neuromasts in the lateral line, and fewer hair cells per neuromast. A similar reduction in neuromast number was observed in coho salmon reared in stormwater. Bioretention treatment, intended to filter out harmful constituents of stormwater, rescued the lateral line defects in zebrafish but not in coho salmon, suggesting that not all of the harmful constituents were removed by the filtration media and that salmonids are particularly sensitive to aquatic toxicants. Collectively, these data demonstrate that sub-lethal exposure to stormwater runoff negatively impacts a fish sensory system, which may have consequences for organismal fitness.

Occurrence and distribution of polycyclic aromatic hydrocarbons in surface sediments of San Diego Bay marinas

Polycyclic aromatic hydrocarbons (PAHs) have garnered much attention due to their bioaccumulation, carcinogenic properties, and persistence in the environment. Investigation of the spatial distribution, composition, and sources of PAHs in sediments of three recreational marinas in San Diego Bay, California revealed significant differences among marinas, with concentrations in one site exceeding 16,000ngg^-1. 'Hotspots' of PAH concentration suggest an association with stormwater outfalls draining into the basins. High-molecular weight PAHs (4-6 rings) were dominant (>86%); the average percentage of potentially carcinogenic PAHs was high in all sites (61.4-70%) but ecotoxicological risks varied among marinas. Highly toxic benzo(a)pyrene (BaP) was the main contributor (>90%) to the total toxic equivalent quantity (TEQ) in marinas. PAHs in San Diego Bay marina sediments appear to be derived largely from pyrogenic sources, potentially from combustion products that reach the basins by aerial deposition and stormwater drainage from nearby streets and parking lots.

Zebrafish as a Vertebrate Model System to Evaluate Effects of Environmental Toxicants on Cardiac Development and Function

Environmental pollution is a serious problem of the modern world that possesses a major threat to public health. Exposure to environmental pollutants during embryonic development is particularly risky. Although many pollutants have been verified as potential toxicants, there are new chemicals in the environment that need assessment. Heart development is an extremely sensitive process, which can be affected by environmentally toxic molecule exposure during embryonic development. Congenital heart defects are the most common life-threatening global health problems, and the etiology is mostly unknown. The zebrafish has emerged as an invaluable model to examine substance toxicity on vertebrate development, particularly on cardiac development. The zebrafish offers numerous advantages for toxicology research not found in other model systems. Many laboratories have used the zebrafish to study the effects of widespread chemicals in the environment on heart development, including pesticides, nanoparticles, and various organic pollutants. Here, we review the uses of the zebrafish in examining effects of exposure to external molecules during embryonic development in causing cardiac defects, including chemicals ubiquitous in the environment and illicit drugs. Known or potential mechanisms of toxicity and how zebrafish research can be used to provide mechanistic understanding of cardiac defects are discussed.

The influence of heart developmental anatomy on cardiotoxicity-based adverse outcome pathways in fish

The developing fish heart is vulnerable to a diverse array of toxic chemical contaminants in freshwater, estuarine, and marine habitats. Globally occurring examples of cardiotoxic agents include dioxins, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). The disruption of cardiac function during the process of heart morphogenesis can lead to adverse outcome pathways (AOPs) that can negatively affect fish survival at hatching as well as later life stages. Proximal impacts include cardiogenic fluid accumulation (edema) and defects of the body axis and jaw that preclude larval feeding. More subtle changes in heart development can produce permanent structural defects in the heart that reduce cardiac output and swimming performance in older fish. In recent decades, the presence of edema in fish embryos and larvae has been a very common bioindicator of cardiotoxicity. However, the different ways that edema forms in fish from different habitats (i.e., freshwater vs. marine, pelagic vs. demersal) has not been rigorously examined. Oil spills are an important source of PAHs in fish spawning areas worldwide, and research is revealing how patterns of cardiogenic edema are shaped by species-specific differences in developmental anatomy and ionoregulatory physiology. Here we review the visible evidence for circulatory disruption across nine freshwater and marine fish species, exposed to crude oils from different parts of the world. We focus on the close interconnectedness of the cardiovascular and osmoregulatory systems during early development, and corresponding implications for fish in hyperosmotic and hyposmotic habitats. Finally, we suggest there may be poorly understood adverse outcomes pathways related to osmotic gradients and water movement within embryos, the latter causing extreme shifts in tissue osmolality.

Identification and Toxicological Evaluation of Unsubstituted PAHs and Novel PAH Derivatives in Pavement Sealcoat Products

Pavement sealcoat products contain high concentrations of unsubstituted polycyclic aromatic hydrocarbons (PAHs), but the assessment of the potential toxicological impact is limited without the inclusion of PAH derivatives. This study determined the concentrations of 23 unsubstituted PAHs, 11 high molecular weight-PAHs (MW302-PAHs), and 56 PAH derivatives, including 10 methyl-PAHs (MPAHs), 10 heterocyclic-PAHs (Hetero-PAHs), 26 nitrated-PAHs (NPAHs), and 10 oxygenated-PAHs (OPAHs) in coal-tar and asphalt based sealcoat products and time point scrapes. Inclusion of MW302-PAHs resulted in an increase of 4.1-38.7% in calculated benzo[a]pyrene-carcinogenic equivalent (B[a]P_eq) concentrations for the coal-tar based products. Increases in some NPAH and OPAH concentrations were measured after application, suggesting the possibility of photochemical transformation of unsubstituted PAHs. The Ames assay indicated that the asphalt based product was not mutagenic, but the coal-tar based sealcoat products were. The zebrafish developmental toxicity tests suggested that fractions where NPAHs and OPAHs eluted have the most significant adverse effects.