Suggested Citation:
Uta Passow, Marisa Wirth, D. Schulz-Bull. 2017. Roller Tank Experiment for the component-specific Investigation of Oil Incorporation into Marine Oil Snow with a Phytoplankton Mixture (t = 4 days). Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7ZP44KS
Data Parameters and Units:
a. Tank number b. Treatment= different treatments and controls were prepared (MilliQ Control = control tank containing only MilliQ water, OC Control = control tank with oil and Corexit in MilliQ water, Plankton Control = control tank containing only the plankton culture, OP = Oil and Plankton treatment, OPC = Oil, Plankton and Corexit treatment) c. Sample Type= in each treatment three different fractions were sampled: MOS = marine oil snow (aggregated, sinking particles > 1mm), PM = particulate matter < 1mm (unaggregated particles and oil drops), DP = dissolved water phase (everything that passes through a 0.7 µm filter) d. Sample volume in L e. Entire fraction volume in L f. DOC = dissolved organic carbon (mg/L) g. POC = particulate organic carbon (mg/L) h. Naph = Naphthalene (ng/mL) i. Acy = Acenaphthylene (ng/mL) j. Ace = Acenaphthene (ng/mL) k. Fl = Fluorene (ng/mL) l. Phen = Phenanthrene (ng/mL) m. Ant = Anthracene (ng/mL) n. Fluo = Fluoranthene (ng/mL) o. Pyr = Pyrene (ng/mL) p. BaA = Benzo(a)anthracene (ng/mL) q. Chr = Chrysene (ng/mL) r. BbF = Benzo(b)fluoranthene (ng/mL) s. BkF = Benzo(k)fluoranthene (ng/mL) t. BaP = Benzo(a)pyrene (ng/mL) u. Ind = Indeno(1,2,3-c,d)pyrene (ng/mL) v. DBA = Dibenzo(a,h)anthracene (ng/mL) w. BP = Benzo(g,h,i)perylene (ng/mL) x-az. Cx = n-alkane with x C-atoms and 2x+2 H-atoms
Methods:
Seven tanks (MilliQ control, Plankton control, Oil and Corexit control and two replicates for OP and OPC treatments) were filled bubble free with MilliQ water (MilliQ control and Oil and Corexit control) or plankton culture (Plankton control and OP and OPC treatments; salinity 16.1 PSU) and sealed. The MilliQ and Plankton control remained unchanged, but oil or oil and Corexit were slowly injected into the center of the already rotating tanks of the Oil and Corexit control and the OP and OPC treatments. For the OP treatments, 50 µl of oil (Marlin Platform, Dorado source oil) and 20 µl of MilliQ water were injected. For the OPC treatments and the Oil and Corexit control, 50 µl of oil, 3 µl of Corexit (Clean Seas) and 20 µl of MilliQ water were used. All tanks were incubated in the dark on the roller tables for 4 days (until MOS had formed). The temperature was 24.3 °C. For sampling, tanks were carefully removed from the roller tables. All formed MOS > 1mm was collected manually with a cut-off pipette. Afterwards, the tanks were sealed again and the contents mixed. Subsamples from this surrounding seawater fraction were subsequently taken. Both the marine snow slurry and the surrounding seawater were filtered onto 0.7 µm borosilicate glass filters (Whatman, UK). Thereby, three different sample categories were obtained. The filtrate from the surrounding seawater was termed the dissolved phase (DP). The respective filter cake was termed particulate matter < 1 mm (PM). It contained unaggregated marine particles as well as oil drops, since they do not pass through the filter. The filter cake from the marine snow slurry was termed marine oil snow (MOS), the respective filtrate was discarded as it contained predominately DP. The pore water fraction of aggregates is too small to sample in this fraction. For n-alkane and PAH analysis, DP samples were mixed with 225 µl of deuterated internal PAH standard solution (LGC Standards, UK) and 1 mL of n-Decane (LGC Standards, UK) and n-Tetracontane (LGC Standards, UK). The samples were extracted twice with 10 mL dichloromethane (Prochem, Germany) and once with 10 mL hexane (Prochem, Germany) for 10 minutes each. The extracts were combined, dried over sodium sulfate (Merck, Germany) and concentrated to about 1 mL trough rotary evaporation. Subsequently, the solutions were purified over an aluminum oxide (Merck, Germany) and silica gel (Merck, Germany) column. The column was conditioned with 10 mL toluene (Prochem, Germany) and 10 mL heptane (Prochem, Germany). Analytes were eluted with 15 mL heptane and 30 mL of a heptane toluene mixture (2:1). The purified extracts were again concentrated to 1 mL. Filters (MOS and PM) were extracted with 15 mL dichloromethane and 15 mL hexane in an ultrasonic bath for 2 hours. The solvents were mixed with the same standard solutions. Afterwards, the samples were treated as described for the DP samples. The samples were measured for PAHs using a Trace DSQ GC-MS system (Thermo Scientific, Germany) equipped with an electron impact ionization source and single quadrupole detector that operates in the SIM mode. The compounds were separated with a 60 m DB-5MS column (Agilent, U.S.). The following PAHs were targeted: Naphthalene (Naph), Acenaphtylene (Acy), Acenaphthene (Ace), Fluorene (Fl) Phenanthrene (Phen), Anthracene (Ant), Fluoranthene (Fluo), Pyrene (Pyr), Benz(a)anthracene (BaA), Chrysene (Chr), Benz(b)fluoranthene (BbF), Benz(k)fluoranthene (BkF), Benz(a)pyrene (BaP), Indeno(1,2,3-c,d)pyren (Ind), Dibenzo(a,h)anthracene (DBA) and Benz(g,h,i)perylene (BP). A self-prepared mixture of internal (deuterated) and external PAH standards (LGC Standards, UK) was measured alongside the samples and used for quantification. The samples were measured for alkanes using a Trace GC Ultra system (Thermo Scientific, Germany) equipped with an FID detector. The analytes were separated with a 30 m DB-5MS column (Agilent, U.S.). The n-alkanes from n-Decane (C10H22) to n-Tetracontane (C40H82) were targeted. An external n-alkane standard (Ultra Scientific, U.S.) was measured alongside the samples and used for quantification. The DP samples were measured for dissolved organic carbon (DOC) and the MOS and PM samples for particulate organic carbon (POC). DOC measurements were carried out with a TOC-LCPH/TOC-VCPH TOC-Analyzer (Shimadzu, Germany). Samples were acidified with 80 µL of 2 N HCl to previously purge inorganic carbon. POC measurements were conducted with a varioMICRO cube element analyzer (Elementar Analysensysteme, Germany). Filters were dried for 30 min, acidified with 100 µL 2N HCl and incubated for 30 min. They were subsequently dried, folded and packed in tin containers for the subsequent measurement. Sample losses: An estimated 15 % of the MOS sample from OP Tank 4 was lost during processing. An estimated 6 % of the oil did not get injected into OP Tank 5. The oil compound sample from OPC Tank 7 could not be measured for PAHs due to instrument failure (only n alkane data available).
Instruments:
The samples were measured for PAHs using a Trace DSQ GC-MS system (Thermo Scientific, Germany) equipped with an electron impact ionization source and single quadrapole detector that operates in the SIM mode. The compounds were separated with a 60 m DB-5MS column (Agilent, U.S.). The samples were measured for alkanes using a Trace GC Ultra system (Thermo Scientific, Germany) equipped with an FID detector. The analytes were separated with a 30 m DB-5MS column (Agilent, U.S.). The DP samples were measured for dissolved organic carbon (DOC) and the MOS and PM samples for particulate organic carbon (POC). DOC measurements were carried out with a TOC-LCPH/TOC-VCPH TOC-Analyzer (Shimadzu, Germany). Samples were acidified with 80 µL of 2 N HCl to previously purge inorganic carbon. POC measurements were conducted with a varioMICRO cube element analyzer (Elementar Analysensysteme, Germany).
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