National Aquarium Conservation Center

Baltimore Highlands, MD, United States

National Aquarium Conservation Center

Baltimore Highlands, MD, United States

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Hong Y.,Johns Hopkins University | Hong Y.,Daegu University | Hong Y.,National Aquarium Conservation Center | Wetzel D.,Mote Marine Laboratory | And 7 more authors.
Environmental Monitoring and Assessment | Year: 2015

One year after the Deepwater Horizon oil spill accident, semipermeable membrane devices (SPMDs) and polyethylene devices (PEDs) were deployed in wetland areas and coastal areas of the Gulf of Mexico (GOM) to monitor polycyclic aromatic hydrocarbons (PAHs). The measured PAH levels with the PEDs in coastal areas were 0.05–1.9 ng/L in water and 0.03–9.7 ng/L in sediment porewater. With the SPMDs, the measured PAH levels in wetlands (Barataria Bay) were 1.4–73 ng/L in water and 3.3–107 ng/L in porewater. The total PAH concentrations in the coastal areas were close to the reported baseline PAH concentrations in GOM; however, the total PAH concentrations in the wetland areas were one or two orders of magnitude higher than those reported in the coastal areas. In light of the significant spatial variability of PAHs in the Gulf’s environments, baseline information on PAHs should be obtained in specific areas periodically. © 2015, Springer International Publishing Switzerland.


PubMed | Texas Tech University, National Aquarium Conservation Center, Johns Hopkins University, Texas Southern University and Mote Marine Laboratory
Type: Journal Article | Journal: Environmental monitoring and assessment | Year: 2015

One year after the Deepwater Horizon oil spill accident, semipermeable membrane devices (SPMDs) and polyethylene devices (PEDs) were deployed in wetland areas and coastal areas of the Gulf of Mexico (GOM) to monitor polycyclic aromatic hydrocarbons (PAHs). The measured PAH levels with the PEDs in coastal areas were 0.05-1.9ng/L in water and 0.03-9.7ng/L in sediment porewater. With the SPMDs, the measured PAH levels in wetlands (Barataria Bay) were 1.4-73ng/L in water and 3.3-107ng/L in porewater. The total PAH concentrations in the coastal areas were close to the reported baseline PAH concentrations in GOM; however, the total PAH concentrations in the wetland areas were one or two orders of magnitude higher than those reported in the coastal areas. In light of the significant spatial variability of PAHs in the Gulfs environments, baseline information on PAHs should be obtained in specific areas periodically.


Hong Y.S.,Johns Hopkins University | Hong Y.S.,National Aquarium Conservation Center | Rifkin E.,National Aquarium Conservation Center | Bouwer E.J.,Johns Hopkins University
Environmental Science and Technology | Year: 2011

A diffusive gradient in thin film technique (DGT) was combined with ion chromatography and inductively coupled plasma mass spectrometry (IC-ICP-MS) for the in situ simultaneous quantification of CH 3Hg + and Hg 2+ in aquatic environments. After diffusing through an agarose diffusive layer, the Hg species accumulated in a thiol-functionalized resin layer and were extracted using acidic thiourea solution to form stable thiourea-Hg complexes that were separated and detected via ion chromatography and ICP-MS, respectively. The effective diffusion coefficients of CH 3Hg + and Hg 2+ complexes in the agarose diffusion layer with chloride were 5.26 (±0.27) × 10 -6 and 4.02 (±0.10) × 10 -6 cm 2 s -1, respectively. The effective diffusion coefficients of CH 3Hg + and Hg 2+ complexes in the agarose diffusion layer with dissolved organic matter was 3.57 (±0.29) × 10 -6 and 2.16 (±0.19) × 10 -6 cm 2 s -1, respectively. The practical method detection limits are 0.1 and 0.7 ng L -1 for CH 3Hg + and Hg 2+ respectively for three weeks deployment. Lower detection limits would be possible by employing a thinner agarose diffusive layer and/or by deploying the probes longer. The method can measure time averaged CH 3Hg + and Hg 2+ concentrations simultaneously in oxic water, making it useful as an in situ monitoring tool. © 2011 American Chemical Society.


Hong Y.-S.,Johns Hopkins University | Hong Y.-S.,National Aquarium Conservation Center | Hull P.,Mote Marine Laboratory | Rifkin E.,National Aquarium Conservation Center | Bouwer E.J.,Johns Hopkins University
Environmental Toxicology and Chemistry | Year: 2013

The bioaccumulation and biomagnification of Hg and Se were investigated in Sarasota Bay, Florida, USA, to characterize the Hg exposure risks to wild bottlenose dolphins in the bay. Concentrations of total mercury (THg), monomethylmercury (MMHg), and total selenium (TSe) were monitored in the bay, the latter of which might reduce Hg toxicity. The food web structure and dolphins' trophic level-specific consumption rates were evaluated using stable isotope ratios of carbon (δ13C) and nitrogen (δ15N). Regressions developed for Hg biomagnification in the food chain were log10CTHg (nanograms per gram)=0.27×δ15N (‰) - 0.42, R2=0.87, for THg and log10CMMHg=0.33×δ15N (‰) - 1.0, R2=0.93, for MMHg. Unlike Hg, nearly constant TSe concentrations were observed at 248±179ngg-1 in the food web, and the TSe-to-THg molar ratio was predicted by log10(CTSe/CTHg)=-0.10×δ15N (‰)+2.8, R2=0.60. The THg-uptake rates of Sarasota bottlenose dolphins are estimated to vary between 2.1 and 4.9μgkg-1 d-1; however, the estimated TSe-uptake rates (15.1μgkg-1 d-1) were higher than those for THg, and the Hg-exposure risks of the Sarasota Bay resident bottlenose dolphins are considered to be low. Approaches employed in the present study can be extended to other environments to characterize Hg contamination in aquatic systems and Hg exposure risks in top predators. © 2013 SETAC.

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