Concentrations of hexabromocyclododecanes (HBCDs), polybrominated diphenyl ethers (PBDEs), and three novel flame retardants, namely2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB), bis-(2-ethylhexyl)-tetrabromophthalate (TBPH), and hexachlorocyclopentadienyldibromocyclooctane (HCDBCO), were determined in blubber samples of Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides). The levels of HBCDs and PBDEs in cetacean samples ranged from 4.1 to 519 and 103 to 51,100 ng/g lw, respectively. A significant increasing trend of SigmaHBCDs was observed in dolphin samples from 1997 to 2007 with an estimated annual rate of 5%, whereas no significant temporal trends of SigmaPBDEs appeared over the sampling period. This pattern may be attributed to the increasing usage of HBCDs following the restriction/voluntary withdrawal of the production and use of PBDE commercial mixtures in several countries. HCDBCO was not found in the blubber samples. This is the first report of the presence of TBB and TBPH, two new flame retardants that have previously been identified in house dust from the U.S., in marine mammals; concentrations of these compounds in dolphins and porpoises ranged from the instrumental detection limit (IDL) (<0.04) to 70 and IDL (<0.04) to 3859 ng/g lw, respectively. Levels of TBPH were comparable to SigmaHBCDs in porpoise samples. The presence of these novel flame retardants in top-trophic-level marine organisms raises concern about their release into the environment and indicates the need for further monitoring of these compounds in other environmental matrices.

Ciguatera fish poisoning (CFP) is a foodborne illness caused by consumption of coral reef fishes contaminated by ciguatoxins (CTXs); of the known CTX congeners, the Pacific ciguatoxins (P-CTXs) are the most toxic. Little is known about the trophodynamics of P-CTXs in coral reef systems. The present study explores the distribution, transfer, and trophic magnification of P-CTX-1, -2, and -3 in coral reef systems with high (ciguatoxic) and low (reference) ciguatoxicity in a CFP-endemic nation by use of liquid chromatography-tandem mass spectrometry (LC-MS/MS). In ciguatoxic coral reef systems, P-CTXs were detected in 54% of herbivorous fishes [total P-CTXs <0.500-1670 pg/g wet weight (ww)], 72% of omnivorous fishes (<0.500-1810 pg/g ww), and 76% of carnivorous fishes (<0.500-69 500 pg/g ww), as well as a lobster ( Panulirus penicillatus ; 2.36 pg/g ww) and an octopus (Octopodidae; 2.56 pg/g ww). The dominant P-CTXs in grazers and piscivorous fishes were P-CTX-2 and -1, respectively. No significant correlation between P-CTX levels and lipid content in three target predatory fishes indicated that accumulation of P-CTXs does not depend on fat content. A weak but significant positive relationship was observed between δ(15)N and P-CTX-1 levels, but further investigation is required to confirm its biomagnification potential.

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Little is known about the occurrences, distributions, sources, and potential risks of organophosphate (OP) triesters and diester degradation products in municipal sludge from wastewater treatment plants (WWTPs). In this study, we conducted the first nationwide survey to simultaneously determine a suite of 11 OP triesters and six diester degradation products in sludge from WWTPs across China. All OP triesters were detected and three diesters were identified for the first time in sludge samples. Total concentrations of OP triesters and diester degradation products were in the ranges of 43.9-2160 and 17.0-1300 ng (g of dry weight), respectively, indicating relatively low pollution levels in China compared with those of several developed countries. A distinct geographical variation of higher concentrations of OP triesters and diesters in East China than in Central and West China was observed, suggesting that regional levels of organophosphate esters are associated with the magnitudes of regional economic development. Source analysis revealed nonchlorinated OP diesters are mainly derived from degradation in WWTPs, while chlorinated OP diesters were largely sourced from outside WWTPs. The estimated total emission fluxes of OP triesters and diesters via land-application sludge in China were approximately 330 and 134 kg/year, respectively. Further risk assessment based on risk quotient values in sludge-applied soils indicated low to medium risks for most OP triesters and diesters except tris(methylphenyl) phosphate. The significant accumulation of OP triesters and widespread occurrence of diester degradation products in sludge raise environmental concerns about these contaminants.

Our previous study revealed an elevated accumulation of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in marine mammals from Hong Kong waters in the South China Sea. To examine the bioaccumulation potential and biomagnification in these apex predators, we sampled the dietary items of marine mammals and tracked the sources of SCCPs and MCCPs through a marine food web in this region. Sixteen fish species, seven crustacean species, and four mollusk species were collected, and the main prey species were identified for two species of marine mammals. Concentrations of ∑SCCPs and ∑MCCPs in these collected species suggested a moderate pollution level in Hong Kong waters compared to the global range. Lipid content was found to mediate congener-specific bioaccumulation in these marine species. Significantly positive correlations were observed between trophic levels and concentrations of ∑SCCPs or ∑MCCPs (p < 0.05). Trophic magnification factors for ∑SCCPs and ∑MCCPs were 4.29 and 4.79, indicating that both of them have trophic magnification potentials. Elevated biomagnification of SCCPs and MCCPs from prey species to marine mammals was observed. This is the first report of dietary source tracking of SCCPs and MCCPs in marine mammals. The elevated biomagnification between prey and marine mammals raises environmental concerns about these contaminants.

Temporal trends of short-(SCCPs) and medium-chain chlorinated paraffins (MCCPs) were examined in blubber samples of 50 finless porpoises (Neophocaena phocaenoides) and 25 Indo-Pacific humpback dolphins (Sousa chinensis) collected from the South China Sea between 2004 and 2014. Elevated levels of SCCPs and MCCPs were detected in all blubber samples of both cetacean species. Concentrations of SCCPs ranged from 280 to 3900 ng·g −1 dry weight (dw) in porpoises and from 430 to 9100 ng·g −1 dw in dolphins, while concentrations of MCCPs ranged from 320 to 8600 ng·g −1 dw in porpoises and from 530 to 23 000 ng·g −1 dw in dolphins. Significantly higher concentrations were present in dolphins than porpoises due to their exposure levels in their living habitats. Strongly linear correlations existed between SCCPs and MCCPs, but there were no significant concentration differences between the genders of the two cetacean species in the same sampling year. Significantly temporal increasing trends of ∑SCCPs and ∑MCCPs have been observed in both porpoise and dolphin samples over the past decade, which reflect the influence of histories of production and usage on the bioaccumulation of CPs in marine mammals in China. An apparent temporal shift trend from SCCPs to MCCPs was also observed in CP accumulation profiles. Complex environmental fractionation from localized sources in the study region via atmospheric transport, oceanic/offshore water transport, and trophic transfer have resulted in different CP accumulation levels and homologue patterns in the two cetacean species. This is the first report of systematic temporal trends of SCCPs and MCCPs in marine mammals.

Per- and polyfluoroalkyl substances (PFASs) have been manufactured and widely used for over 60 years. Currently, there are thousands of marketed PFASs, but only dozens of them are routinely monitored. This work involved target, nontarget, and suspect screening of PFASs in the liver of Indo-Pacific humpback dolphin (Sousa chinensis) and finless porpoise (Neophocaena phocaenoides), two resident marine mammals in the South China Sea, stranded between 2012 and 2018. Among the 21 target PFASs, perfluorooctane sulfonate and 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA) predominated in the samples, accounting for 46 and 30% of the total PFASs, respectively. Significantly higher total target PFAS concentrations (p < 0.05) were found in dolphin liver samples [3.23 × 103 ± 2.63 × 103 ng/g dry weight (dw)] than in porpoise liver samples (2.63 × 103 ± 1.10 × 103 ng/g dw). Significant increasing temporal trends (p < 0.05) were found in the concentrations of two emerging PFASs, perfluoroethylcyclohexane sulfonate and 2,3,3,3-tetrafluoro-2-propanoate in porpoises, indicating increasing pollution by these emerging PFASs. Forty-four PFASs from 9 classes were additionally identified by nontarget and suspect screening, among which 15 compounds were reported for the first time in marine mammals. A primary risk assessment showed that the emerging PFAS 6:2 Cl-PFESA could have possible adverse effects in terms of reproductive injury potential on most of the investigated cetaceans.