Nontargeted biomonitoring of halogenated organic compounds in two ecotypes of bottlenose dolphins (Tursiops truncatus) from the Southern California Bight.

Targeted environmental monitoring reveals contamination by known chemicals, but may exclude potentially pervasive but unknown compounds. Marine mammals are sentinels of persistent and bioaccumulative contaminants due to their longevity and high trophic position. Using nontargeted analysis, we constructed a mass spectral library of 327 persistent and bioaccumulative compounds identified in blubber from two ecotypes of common bottlenose dolphins (Tursiops truncatus) sampled in the Southern California Bight. This library of halogenated organic compounds (HOCs) consisted of 180 anthropogenic contaminants, 41 natural products, 4 with mixed sources, 8 with unknown sources, and 94 with partial structural characterization and unknown sources. The abundance of compounds whose structures could not be fully elucidated highlights the prevalence of undiscovered HOCs accumulating in marine food webs. Eighty-six percent of the identified compounds are not currently monitored, including 133 known anthropogenic chemicals. Compounds related to dichlorodiphenyltrichloroethane (DDT) were the most abundant. Natural products were, in some cases, detected at abundances similar to anthropogenic compounds. The profile of naturally occurring HOCs differed between ecotypes, suggesting more abundant offshore sources of these compounds. This nontargeted analytical framework provided a comprehensive list of HOCs that may be characteristic of the region, and its application within monitoring surveys may suggest new chemicals for evaluation

Persistent Organic Pollutants and Mercury in Genetically Identified Inner Estuary Bottlenose Dolphin (Tursiops truncatus) Residents of the Guayaquil Gulf, Ecuador: Ecotoxicological Science in Support of Pollutant Management and Cetacean Conservation

The bottlenose dolphin is one of the most common cetaceans found in the coastal waters, estuaries, and mangroves of Ecuador. However, its population size is gradually declining in the Gulf of Guayaquil, and anthropogenic factors including habitat degradation, uncontrolled dolphin watching, dredging activities, increasing maritime traffic, underwater noise, bycatch, and marine pollution have been implicated in their decline. Very little is known about contamination by persistent organic pollutants (POPs) and mercury in bottlenose dolphins from the Pacific coast of South America. To address this research gap, the first assessment of total mercury (THg) and POPs, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs), in free-ranging bottlenose dolphins in mangroves (El Morro Mangrove Wildlife Refuge) of the Gulf of Guayaquil, was conducted in Ecuador in 2018. Dolphin samples (i.e., skin and blubber; n = 9), were obtained using dart biopsy field methods for contaminant analysis. POP concentrations ranged from 0.56 to 13.0 mg/kg in lipid weight, while THg ranged from 1.92 to 3.63 mg/kg in dry weight. The predominant POPs were OCPs (50% of ΣPOP), followed by PCBs (46%) and PBDEs (6.0%); particularly, p,p′-DDE, the main DDT metabolite and a potent anti-androgenic, accounting for 42% of ΣPOP, ranging from 0.12 to ∼7.0 mg/kg lw, followed by PCB 153 (8.0%) and PCB 180 (5.0%). PBDE 47 accounted for 2.0% of ΣPOP. While the POP concentrations are lower than those found in dolphins from many other regions of the world, some of the THg concentrations are within the concentration range found in dolphins from the southeastern coast of the United States. The ecotoxicological risk assessment showed that some of the sampled dolphins are exposed to immunotoxic and endocrine disruption effects by POPs and mercury. The low genetic diversity of this distinctive dolphin population, likely exhibiting genetic isolation and a unique evolutionary heritage, could be lost if the population continues to decline in the face of anthropogenic threats, including chemical pollution. Our finding shows that bottlenose dolphins in coastal Ecuador are exposed to environmental contaminants and can be used as sentinel species for ecosystem health to monitor pollution in the region and to support ecotoxicological risk assessment and regional pollutant management

Advancing the use of passive sampling in risk assessment and management of contaminated sediments: Results of an international passive sampling inter-laboratory 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

Partitioning and Bioavailability of Polynuclear Aromatic Hydrocarbons in an Intertidal Marsh

Polycyclic aromatic hydrocarbons (PAHs) are trace organic pollutants now so ubiquitous in aquatic ecosystems that the major organic signature in urban storm runoff is that of weathered PAHs. PAHs are formed by combustion of organic matter including petroleum and wood but anthopogenically produced PAHs have increased greatly over the last century. PAHs are a problem in the environment since some are potent carcinogens to humans and wildlife alike. PAHs include the most toxic fraction of tobacco smoke, benzo(a)pyrene, naphalene, and phenanthrene and are often found in association with other organic pollutants such as chlorinated biphenyls (PCBs), and organochlorine compounds such as DDT. The persistence of PAHs in the environment and their concentration in the fat of living organisms increases the toxicity of PAHs and current regulatory standards are based on the bulk concentration of PAHs in the sediments and the amount of organic carbon in the sediments. Our research was intended to improve the understanding of PAHs in sediments, particularly the spatial and temporal variations in the bioavailabilty and bioaccumulation in shellfish and polychaete worms in the sediments of the San Francisco Bay Estuary.We concentrated on 18 individual PAH compounds and measured their seasonal and spatial variations in the intertidal sediments and biota. We found that the sediment pore water concentration of PAHs may be more important in determining the bioconcentration of PAHs in living tissue than the simple bulk concentrations in the sediments. Similarly, we found that the kind of organic carbon present is more important in determining the bioconcentration of PAHs in shellfish and polychaete worms than the simple total amount of carbon present. The explanation is probably that silt and small organic fragments, especially soot, may be mostly composed of PAHs while other organic carbon such a decaying leaves is not. Soot contains a lot of PAHs but they are strongly bound to the carbon matrix and are paradoxically less bioavailable than lower amounts of PAH bound to naturally-occurring carbon. Winter storms carrying accumulated sooty fallout and auto crankcase drippings from the watershed and depositing them preferentially in the upper intertidal of the estuary explains the observed PAH speciation and distribution as well as the observed bioconcentration patterns in the sediment-dwelling biota. We recommend that attention be paid to the kind of organic carbon and its site in the porewaters in the setting of future regulatory standards