Data Parameters and Units:
2. PAH Mobilization - concentration (ng/ml) - Control, Oil, Oil+Corexit: Acenapthalyne, Anthracene, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(ghi)perylene, Chrysene, Dibenz(a,h)anthracene, Fluorene, Indeno(123-cd)pyrene, Phenanthrene 3. PAH Distribution - depth (cm) and concentration (ng/Kg) - Control, Oil, Oil+Corexit: Acenapthalyne, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(k)fluoranthene, Chrysene, Fluorene, Phenanthrene 4. Cumulative release - effluent volume (ml) - Control, Oil, Oil+Corexit: Chrysene (ng), Acenapthalyne (ng) 5. Fluorescence - average (nm) and std (nm) - Control, Oil, Oil+Corexit: scanning the core with 710 nm blue-enriched light and converting the averaged fluorescence measurements for each depth interval into oil concentrations 6. PAH compound concentration (ng/L) - Control, Oil, Oil+Corexit: Acenapthalyne, Anthracene, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(ghi)perylene, Chrysene, Dibenz(a,h)anthracene, Fluorene, Indeno(123-cd)pyrene, Phenanthrene 7. Chamber - sediment contribution (mg/m2d) - Control, Tarball 8. Short column experiment - Percentage of PAH concentration (ng/L) that was retained in the sediment (%) - Control I, Control II, treatment I, treatment II - sum, water, water %, sediment, sediment %: Acenapthalyne, Anthracene, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(ghi)perylene, Chrysene, Dibenz(a,h)anthracene, Fluorene, Indeno(123-cd)pyrene, Phenanthrene 9. Average pen depth (cm), log KOW: Acenapthalyne, Anthracene, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(ghi)perylene, Chrysene, Dibenz(a,h)anthracene, Fluorene, Indeno(123-cd)pyrene, Phenanthrene
Methods:
2. PAH concentrations in seawater after the addition of oil or oil and Corexit. 5 ml oil (MC252 oil) dispersed either mechanically (ultrasound treatment for 2 minutes) or mechanically and chemically (addition of 50 mL Corexit, ultrasound treatment for 2 minutes), were thoroughly mixed with 8 L of natural seawater each, and after 24 h incubation in the dark at 22uC, samples were extracted for PAH analysis. Controls were seawater without any additions. 3. Short and Long Column Experiments. The water overlying the sand columns percolates through the sands by gravitation, similar to the process occurring when water washed up the beach is penetrating into the beach face by gravity. All water exiting each column was collected as 4 separate samples, each between 20 and 30 mL, to obtain a time series of effluent PAH concentrations. After the fluorescence measurements, the sand columns were sectioned at 2.5 cm intervals and the hydrocarbons were extracted from each layer using standard procedures. 4. Cumulative outflow of PAHs in the water from the short column experiment. All water exiting each column was collected as 4 separate samples, each between 20 and 30 mL, to obtain a time series of effluent PAH concentrations. The PAH data were plotted as cumulative values. 5. Distribution of fluorescence in the sand was measured through the transparent core liners. A fiber-optic probe emitting pulses of blue-enriched light (710 nm) was used to measure fluorescence at different sediment depths. Fluorescence produced by oil-stained sand was returned through the fiber-optic cable to a photodiode protected by a long-pass filter (710 nm). The amplified output signal of the photodiode produced the measuring signal. Each scanning of an experimental core was followed by a scan of a calibration core used to convert the averaged fluorescence measurements for each depth interval into oil concentrations. 6. 10, 25, and 50 cm sand column experiments. The water overlying the sand columns percolates through the sands by gravitation, similar to the process occurring when water washed up the beach is penetrating into the beach face by gravity. All water exiting each column was collected as 4 separate samples, then an additional 300 mL of clean artificial seawater was added to each column, all water of each column was collected in a 500 mL flask, to obtain a time series of effluent PAH concentrations. 7. Six advection chambers. Assess the release of aromatic hydrocarbonbs from the tarballs under field conditions. Tarballs and Pensacola Beach sand in advection chambers stirred by a rotating disc adjusted to produce a radial pressure gradient (0.1 Pa cm 1) mimicking the pressure gradients caused by moderate bottom flows (10 cm s-1 at 10 cm above the sediment surface) deflected by sand ripples (3 cm amplitude, 30 cm wavelength). 8. Composition of the percolating water in the Short and Long Column Experiments. the water overlying the sand columns to percolate through the sands by gravitation, similar to the process occurring when water washed up the beach is penetrating into the beach face by gravity. All water exiting each column was collected as 4 separate samples, each between 20 and 30 mL, to obtain a time series of effluent PAH concentrations. After the fluorescence measurements, the sand columns were sectioned at 2.5 cm intervals and the hydrocarbons were extracted from each layer using standard procedures. 9. As a measure for hydrophobicity, we used the octanol-water partition coefficient (KOW), which represents the ratio of the solubility of the hydrocarbon in the non-polar solvent octanol to its solubility in the polar solvent water. The Log KOW values, which are inversely related to aqueous solubility and directly proportional to molecular weight, are a relative indicator of the tendency of an organic compound to adsorb to sediment.
Instruments:
The laboratory column reactors used for this experiment consisted of transparent acrylic core liners (3.6 cm i.diam., 30 cm long) that were sealed at the bottom with gauze-covered stoppers preventing sand from clogging the stopcock that controlled the outflow of the columns. Oil-free sand, collected from the upper part of the public beach at Pensacola Beach, Florida, (30°19'33.96"N, 87°10'28.87"W), was sieved to remove shell hash and large organic debris. The sand fraction smaller 500 μm was filled into the core liners to produce 10 cm sand columns saturated with artificial seawater (S=33, created with Instant Ocean®). This procedure resulted in sand columns with similar permeabilities allowing comparison of the columns and quantifiable percolation rates. Control 100 mL artificial seawater (+ rinse with 300 ml artificial seawater)periments were conducted that differed in their composition of the percolating water. Oil 100 mL artificial seawater with 1 mL oil dispersed into small droplets by ultrasound treatment (+ rinse with 300 ml artificial seawater). Oil+Corexit II 100 mL artificial seawater with 1 mL oil dispersed by Corexit 9500A addition at 1:100 dispersant to oil ratio and ultrasound treatment (+ rinse with 300 ml artificial seawater). Six advection chambers, with an inner diameter of 19 cm and enclosing a water column of approximately 15 cm height above a sediment surface of 283 cm2, were deployed at 1.5 m water depth on sublittoral sands at Pensacola Beach/Florida.
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