Temporal and Spatial Assessment of PAHs in Water, Sediment, and Oysters as a Result of the Deepwater Horizon Oil Spill

On April 20, 2010, BP\u27s Deepwater Horizon oil rig exploded leaking over 200 million gallons of crude oil into the Gulf of Mexico for 84 days. Exposure to oil-associated polycyclic aromatic hydrocarbons (PAHs) in the water and sediment could severely impact the aquatic organisms inhabiting the Gulf of Mexico (i.e. developmental defects, reproductive effects, death, etc.). Therefore, water, sediment and oyster, Crassostrea virginica, samples were collected approximately bimonthly between May 26 and November 30, 2010 from multiple sites along the Gulf Coast, namely, two sites in Mobile Bay (Denton and Sand Reefs at 1 or 0.1 m above the bay floor), one site near Orange Beach, AL (Perdido), and one near Pointe aux Pines, MS. Water, sediment, and oysters were extracted for quantitation of 24 PAHs by gas chromatography mass spectrometry (GC/MS). The concentration range for total PAHs (tPAH) in water was non-detectable to 1100 ng/L and non-detectable to 7450 ng/g for sediment. The highest water tPAH concentrations were observed on 6/28/10 for Sand (1 m), 7/21/10 for Denton (0.1 m), 9/9/10 for Perdido, and 9/22/10 for Pointe aux Pines. The highest sediment concentrations were observed on 9/20/10 for Denton Reef, 7/7/10 for Sand Reef, 7/28/10 for Perdido, and 9/22/10 for Pointe aux Pines. Twenty other sites along the northern Gulf coast collected less frequently also indicated relatively low (\u3c20 ng/L) tPAH water concentrations. Fundulus heteroclitus embryos were exposed to water collected from three of the sites from 4.5 hours post-fertilization (hpf) to 10 days post-fertilization (dpf). Embryos were assessed on 5 and 10 dpf for lethality and cardiac toxicities (including blood clot, edema and tube heart), and cytochrome P450 enzyme induction was measured by an in ovo ethoxyresorufin-O-deethylase assay. F. heteroclitus embryos were not significantly affected by the water collected from these sites. There was less than 4% and 2% incidence of edema and blood clot, respectively, and there were no significant differences in deformity index or lethality. None of the 73 sediment and 70 water samples collected between May 26, 2010 to February 9, 2011 was definitively impacted by the Deepwater Horizon Oil Spill at the times collected based on the tPAHs measured. However, samples with relatively higher percent compositions of naphthalenes and/or phenanthrene occurred in the Sand and Denton 6/28/10 water samples and in the 7/12/10 Gulf Island National Seashore sediment sample. Other sediment samples with tPAH concentrations greater than 1300 ng/g dry weight had diverse mixtures of the individual PAH compounds suggesting multiple potential sources of contamination. Also, none of the sediment samples at the times collected had tPAH concentrations which exceeded NOAA regulatory SQuiRT guidelines. Therefore, none of the PAH concentrations measured were expected to cause acute toxicity to aquatic life, a result supported by the F. heteroclitus bioassay

Hydrogeophysical Evidence for Ground Water Mixing at Freeling Spring Group, South Australia

The Great Artesian Basin (GAB) is an aquifer system that extends across Australia covering over 22% of the continent and is a vital support system for ecosystems in the region. As part of the Australian National Water Commission's (NWC) GAB Project, research is being conducted to understand the aquifer including studying the discharge of springs and determining flow paths of the aquifer. Water sampling at springs that are a part of the Freeling Spring Group were used along with Electrical Resistivity Imaging (ERI) data to evaluate evidence of mixing between the GAB aquifer and waters from the adjacent basement aquifer in the Peake and Dennison Ranges (PD). Nine springs were used to evaluate fluid chemistry of the Freeling Spring Group. ERI data were collected along three orientations over the Freeling Spring site. The ERI data, which extend for 550 meters laterally and 110 meters vertically, indicate three possible flow lines providing mixing at the spring orifice similar to what would be predicted from traditional conceptual models. Regional water samples of springs were used as end members to evaluate chemical mixing models for waters at the site. The chemistry of spring water samples indicates that the water emanating from the Freeling Spring Group is a mixture of waters from both the GAB and the PD, which confirms the ERI evidence for mixing at the site. The data suggest the mixing occurs along a structural feature in the Peake and Dennison Ranges and that the spring water maintains a strong PD signature even well east of the fault zone.Boone Pickens School of Geolog

Assimilation of Oil-Derived Elements by Oysters Due to the Deepwater Horizon Oil Spill

During and after the Deepwater Horizon Oil Spill (DWHOS), oysters (Crassostrea virginica) were exposed to oil and susceptible to incidental consumption of surface and subsurface oil materials. We determined the contribution of oil materials from the DWHOS to diet of oysters by comparing carbon (C) and nitrogen (N) stable isotope ratios in oyster shell to ratios in suspended particulate matter (SPM) and in fresh and weathered oil. Average δ13C and δ15N values in oyster shell (−21 ± 1‰ and 9−11‰, respectively) were consistent with consumption of naturally available SPM as opposed to values in oil (−27 ± 0.2‰, 1.6 ± 0.4‰). Stable isotope ratios in oyster adductor muscle were similar to shell for δ15N but not δ13C, suggesting either a recent shift in diet composition or differential assimilation of C between tissue types. We found no evidence of assimilation of oil-derived C and N and, therefore, no evidence of an oyster-based conduit to higher trophic levels. Trace elements in shell were inconclusive to corroborate oil exposure. These findings are not an indication that oysters were not exposed to oil; rather they imply oysters either did not consume oil-derived materials or consumed too little to be detectable compared to natural diet

Geophysical Investigation of Oil Brine Contamination: Providing Hands-On Geophysical Experience for Students

From 1917-1973 oil production took place in Wildhorse Field, directly south of Skiatook Lake in Osage County, Oklahoma. During operation two open pits were used for water and oil waste. After operation ceased the two pits were left unregulated on site. The pits are the source of salt contamination in the bedrock, aquifer, and lake. On the surface a salt scar is visible. As part of a geophysical field methods course at Oklahoma State University students acquired electrical, and geochemical data to characterize the salt plume and site geology. Electrical methods used include electrical resistivity, induced-polarization, and spontaneous-potential. The preliminary results show three geoelectric units consisting of a very conductive layer ( & lt; 3 Ohm-meters) sandwiched between resistive units. Both the geochemical and electrical data suggest that the extent of the salt plume is much wider than previously defined

Assimilation of Oil-Derived Elements by Oysters Due to the Deepwater Horizon Oil Spill

During and after the Deepwater Horizon Oil Spill (DWHOS), oysters (<i>Crassostrea virginica</i>) were exposed to oil and susceptible to incidental consumption of surface and subsurface oil materials. We determined the contribution of oil materials from the DWHOS to diet of oysters by comparing carbon (C) and nitrogen (N) stable isotope ratios in oyster shell to ratios in suspended particulate matter (SPM) and in fresh and weathered oil. Average δ¹³C and δ¹⁵N values in oyster shell (−21 ± 1‰ and 9–11‰, respectively) were consistent with consumption of naturally available SPM as opposed to values in oil (−27 ± 0.2‰, 1.6 ± 0.4‰). Stable isotope ratios in oyster adductor muscle were similar to shell for δ¹⁵N but not δ¹³C, suggesting either a recent shift in diet composition or differential assimilation of C between tissue types. We found no evidence of assimilation of oil-derived C and N and, therefore, no evidence of an oyster-based conduit to higher trophic levels. Trace elements in shell were inconclusive to corroborate oil exposure. These findings are not an indication that oysters were not exposed to oil; rather they imply oysters either did not consume oil-derived materials or consumed too little to be detectable compared to natural diet

Multifunctional, Tunable Metal–Organic Framework Materials Platform for Bioimaging Applications

Herein, we describe a novel multifunctional metal–organic framework (MOF) materials platform that displays both porosity and tunable emission properties as a function of the metal identity (Eu, Nd, and tuned compositions of Nd/Yb). Their emission collectively spans the deep red to near-infrared (NIR) spectral region (∼614–1350 nm), which is highly relevant for in vivo bioimaging. These new materials meet important prerequisites as relevant to biological processes: they are minimally toxic to living cells and retain structural integrity in water and phosphate-buffered saline. To assess their viability as optical bioimaging agents, we successfully synthesized the nanoscale Eu analog as a proof-of-concept system in this series. In vitro studies show that it is cell-permeable in individual RAW 264.7 mouse macrophage and HeLa human cervical cancer tissue culture cells. The efficient discrimination between the Eu emission and cell autofluorescence was achieved with hyperspectral confocal fluorescence microscopy, used here for the first time to characterize MOF materials. Importantly, this is the first report that documents the long-term conservation of the intrinsic emission in live cells of a fluorophore-based MOF to date (up to 48 h). This finding, in conjunction with the materials’ very low toxicity, validates the biocompatibility in these systems and qualifies them as promising for use in long-term tracking and biodistribution studies