Our library features many hundreds of entries.

To search among them, click "Search" below to pull down options, including filtering by document type, author, year, and keyword.
Find these options under "Show only items where." Or you can also sort by author, title, type, and year clicking the headings below.

Export 5 results:
Filters: Author is Da Chen  [Clear All Filters]
Journal Article (Peer-Reviewed)
Sutton, R.; Chen, D.; Sun, J.; Greig, D. J.; Wu, Y. 2019. Characterization of brominated, chlorinated, and phosphate flame retardants in San Francisco Bay, an urban estuary. Science of the Total Environment 652, 212-223 . SFEI Contribution No. 859.

Flame retardant chemical additives are incorporated into consumer goods to meet flammability standards, and many have been detected in environmental matrices. A uniquely wide-ranging characterization of flame retardants was conducted, including polybrominated diphenyl ethers (PBDEs) and 52 additional brominated, chlorinated, or phosphate analytes, in water, sediment, bivalves, and harbor seal blubber of San Francisco Bay, a highly urbanized estuary once considered a hot spot for PBDE contamination. Among brominated flame retardants, PBDEs remained the dominant contaminants in all matrices, though declines have been observed over the last decade following their phase-out. Hexabromocyclododecane (HBCD) and other hydrophobic, brominated flame retardants were commonly detected at lower levels than PBDEs in sediment and tissue matrices. Dechlorane Plus (DP) and related chlorinated compounds were also detected at lower levels or not at all across all matrices. In contrast, phosphate flame retardants were widely detected in Bay water samples, with highest median concentrations in the order TCPP > TPhP > TBEP > TDCPP > TCEP. Concentrations in Bay water were often higher than in other estuarine and marine environments. Phosphate flame retardants were also widely detected in sediment, in the order TEHP > TCrP > TPhP > TDCPP > TBEP. Several were present in bivalves, with levels of TDCPP comparable to PBDEs. Only four phosphate flame retardants were detected in harbor seal blubber: TCPP, TDCPP, TCEP, and TPhP. Periodic, multi-matrix screening is recommended to track contaminant trends impacted by changes to flammability standards and manufacturing practices, with a particular focus on contaminants like TDCPP and TPhP that were found at levels comparable to thresholds for aquatic toxicity.

Wu, Y.; Tan, H.; Sutton, R.; Chen, D. 2017. From Sediment to Top Predators: Broad Exposure of Polyhalogenated Carbazoles in San Francisco Bay (U.S.A.). Environmental Science and Technology 51, 2038-2046.

The present study provides the first comprehensive investigation of polyhalogenated carbazoles (PHCZ) contamination in an aquatic ecosystem. PHCZs have been found in soil and aquatic sediment from several different regions, but knowledge of their bioaccumulation and trophodynamics is extremely scarce. This work investigated a suite of 11 PHCZ congeners in San Francisco Bay (United States) sediment and organisms, including bivalves (n = 6 composites), sport fish (n = 12 composites), harbor seal blubber (n = 18), and bird eggs (n = 8 composites). The most detectable congeners included 3,6-dichlorocarbazole (36-CCZ), 3,6-dibromocarbazole (36-BCZ), 1,3,6-tribromocarbazole (136-BCZ), 1,3,6,8-tetrabromocarbazole (1368-BCZ), and 1,8-dibromo-3,6-dichlorocarbazole (18-B-36-CCZ). The median concentrations of ΣPHCZs were 9.3 ng/g dry weight in sediment and ranged from 33.7 to 164 ng/g lipid weight in various species. Biomagnification was observed from fish to harbor seal and was mainly driven by chlorinated carbazoles, particularly 36-CCZ. Congener compositions of PHCZs differed among species, suggesting that individual congeners may be subject to different bioaccumulation or metabolism in species occupying various trophic levels in the studied aquatic system. Toxic equivalent (TEQ) values of PHCZs were determined based on their relative effect potencies (REP) compared to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The median TEQ was 1.2 pg TEQ/g dry weight in sediment and 4.8 – 19.5 pg TEQ/g lipid weight in biological tissues. Our study demonstrated the broad exposure of PHCZs in San Francisco Bay and their characteristics of bioaccumulation and biomagnification along with dioxin-like effects. These findings raise the need for additional research to better elucidate their sources, environmental behavior, and fate in global environments.

Shimabuku, I.; Chen, D.; Wu, Y.; Miller, E.; Sun, J.; Sutton, R. 2022. Occurrence and risk assessment of organophosphate esters and bisphenols in San Francisco Bay, California, USA. Science of the Total Environment 813 . SFEI Contribution No. 982.

Organophosphate esters (OPEs) and bisphenols are two classes of industrial chemicals that are ubiquitously detected in environmental matrices due to high global production and widespread use, particularly in the manufacture of plastic products. In 2017, water samples collected throughout the highly urbanized San Francisco Bay were analyzed for 22 OPEs and 16 bisphenols using liquid chromatography-electrospray ionization-Q Trap-mass spectrometry. Fifteen of the 22 OPEs were detected, with highest median concentrations in the order TCPP (42 ng/L) > TPhP (9.5 ng/L) > TBOEP (7.6 ng/L) > TnBP (7.5 ng/L) > TEP (6.7 ng/L) > TDCIPP (6.2 ng/L). In contrast, only two of 16 bisphenols, BPA and BPS, were quantified, with concentrations ranging from <0.7–35 ng/L and <1–120 ng/L, respectively. BPA and a few OPEs (EHDPP and TEHP) were primarily present in the particulate phase, while BPS and all other observed OPEs were predominantly found in the dissolved phase. Pairwise correlation analysis revealed several strong, positive correlations among OPEs, and few weak, negative correlations between OPEs and BPA, suggesting differences between the two classes with respect to their sources, pathways, and/or fate in the environment. Concentrations of OPEs and bisphenols observed in this study were generally consistent with reported concentrations in other estuarine and marine settings globally. TDCIPP exceeded existing predicted no-effect concentrations (PNECs) at some sites, and six other compounds (TCrP, IDDPP, EHDPP, TPhP, TBOEP, and BPA) were observed at levels approaching individual compound PNECs (not considering mixture effects), indicating potential risks to Bay biota. These results emphasize the need to control releases of these contaminants in order to protect the ecosystem. Periodic monitoring can be used to maintain vigilance in the face of potential regrettable substitutions.

Miscellaneous
 (2.12 MB) (1.31 MB) (2.73 MB)
Report
 (17.47 MB) (10.87 MB)