Constraining the spatial extent of Marine Oil Snow Sedimentation and

Subscriber access provided by CORNELL UNIVERSITY LIBRARY

Article

Constraining the spatial extent of Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) following the Deepwater Horizon Event using an excess 210Pb flux approach Patrick Thomas Schwing, Gregg R. Brooks, Rebekka Larson, Charles Holmes, Bryan O'Malley, and David J. Hollander Environ. Sci. Technol., Just Accepted Manuscript • Publication Date (Web): 14 May 2017 Downloaded from http://pubs.acs.org on May 22, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 27

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Environmental Science & Technology

Constraining the spatial extent of Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) following the Deepwater Horizon Event using an excess 210Pb flux approach Authors: Schwing, P.T.1 (corresponding author), Brooks, G.R.2, Larson, R.A.1,2, Holmes, C.W.3, O’Malley, B.J.1, Hollander, D.J.1 1. University of South Florida, College of Marine Science. 140 7th Ave. S., Saint Petersburg, FL 33701, U.S.A. Phone 001-720-394-7592, Fax 001727-553-1109, Email: [email protected] 2. Eckerd College, 4200 54th Ave. S., Saint Petersburg, FL 33711, U.S.A. 3. Environchron, 3988 Emerald Chase Dr., Tallahassee, FL, 32308, U.S.A Keywords: radioisotopes, sedimentation, oil spill, deepwater horizon, gulf of mexico, MOSSFA, marine snow

18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

ACS Paragon Plus Environment


39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

Abstract Following the Deepwater Horizon (DWH) event in 2010, there were several lines of evidence indicating the presence of Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA). A significant amount of marine oil snow formed in the water column of the northern Gulf of Mexico (nGoM), settled rapidly and ultimately accumulated in the sediments of the nGoM. This study utilized a commonly used radioisotope tracer (excess 210Pb, 210Pbxs) from 32 sediment cores collected from 2010-2013 to characterize the spatial extent of MOSSFA on the seafloor. Relative to pre-DWH conditions, an increase in 210Pbxs flux, occurred in two distinct regions: 1) in the western portion of the study area on an east-northeast to west-southwest axis, stretching 230 km southwest and 140 km northeast of the DWH wellhead, and 2) in the eastern portion of the study area on a 70 km northeast to southwest axis near the DeSoto Canyon. The total sedimentary spatial extent of MOSSFA, as calculated by increased 210Pbxs flux after 2010, ranged from 12,805-35,425 km2. 210Pbxs flux provides a valuable tool for documenting the spatial extent of MOSSFA following DWH and will continue to aid in the determination of advective transport and ultimate depocenters of MOSSFA material.

69 70 71 72 73


Page 2 of 27

Page 3 of 27

74


Introduction

75

The Deepwater Horizon (DWH) event released over 600 million liters of

76

petroleum into the Gulf of Mexico over the course of 87 days in 2010 (Atlas and

77

Hazen, 2011). Formation of oiled flocculent material, predominantly at the surface

78

and throughout the water column, was facilitated by the secretion of exopolymeric

79

substances as a biological stress response from microbes and phytoplankton

80

(Passow et al., 2012; Ziervogel et al., 2012). The oiled flocculent material including

81

oil mineral aggregates began to sink at rates on the order of hundreds-of-meters per

82

day (Daly et al., 2016). The increase in flocculent hydrocarbon deposition has been

83

termed Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA).

84

MOSSFA caused a 4-10 fold increase in sedimentary mass accumulation rates

85

(Brooks et al., 2015), a three-fold increase in sedimentary polycyclic aromatic

86

hydrocarbons (PAH)(Romero et al. 2015), as well as a persistent intensification of

87

reducing conditions at the sediment water interface until 2013 (Hastings et al.,

88

2016), which severely impacted benthic faunal density and diversity (Montagna et

89

al., 2013; Schwing et al., 2015; Schwing et al., 2016A).

90

Constraining the spatial scale of MOSSFA is necessary from an oil budget

91

perspective and for determining how much petroleum was deposited in the

92

sediments following DWH. A few studies have constrained the spatial extent of the

93

petroleum fraction of MOSSFA using radiocarbon proxies or direct measurements of

94

petroleum compounds in the surface sediments relative to down-core

95

concentrations (Valentine et al., 2014; Chanton et al., 2015). Valentine et al., (2014)

96

identified an area of approximately 3,200 km2 with elevated hopane concentrations



97

in surface sediments surrounding the wellhead, which by proxy accounts for 4-31%

98

of the petroleum budget deposited in the sediments of the northern Gulf of Mexico

99

(nGoM). However, they attribute this increase in hopanes primarily to petroleum

100

intrusions in the water column and not necessarily to MOSSFA. Chanton et al.,

101

(2015) found that 3.0-4.9% of the oil was deposited on the seafloor throughout a

102

24,000 km2 area in the northern Gulf of Mexico using a radiocarbon mass balance

103

approach. While these studies focused on determining the petroleum fraction

104

deposited in the sediments, it is also necessary to constrain the total spatial extent

105

of increased flux of flocculent material from the water column. This study utilized

106

sedimentary inventories and fluxes of a commonly used radioisotope tracer (excess

107

210Pb, 210Pbxs)

108

sedimentation following DWH.

109

210Pb

to characterize the spatial expression of increased flocculent

is a naturally occurring radioisotope that has been used to study

110

sediment dynamics and sedimentary accumulation for records on the order of 100

111

years (half life of 22.1 years)(Holmes, 2001).

112

been used in the nGoM and elsewhere to determine particle scavenging in the water

113

column (Baskaran and Santschi, 2002), identify sediment depositional fluxes and

114

transport pathways (Muhammed et al., 2008), and constrain areas of high organic

115

matter deposition (Gordon and Goñi, 2004, Yeager et al., 2004, Sampere et al.,

116

2011). Brooks et al. (2015) characterized the mass accumulation rates of flocculent

117

material following DWH using 210Pbxs and 234Thxs geochronologies at certain sites

118

primarily in the northeastern Gulf of Mexico. This study seeks to build on the work

119

of Brooks et al., (2015) by using a broader collection of cores throughout the nGoM

210Pbxs

inventories and fluxes have


Page 4 of 27

Page 5 of 27


120

and 210Pbxs fluxes to characterize the extent of increased oiled-flocculent material

121

following DWH.

122

Methods

123

Sediment cores were collected at 32 sites from 2010-2013 throughout the

124

nGoM (Figure 1, Table 1) using an Ocean Instruments MC-800 multicoring system,

125

which collects eight cores (diameter: 10 cm, length: up to 70 cm) simultaneously,

126

one of which was used from each site for short-lived radioisotope analysis. Cores

127

were refrigerated (~4O C) and sub-sampled by extrusion at 2 mm intervals for the

128

upper 100 mm and 5 mm intervals for the remainder of each core using a calibrated,

129

threaded-rod extrusion device (Schwing et al., 2016B). Once extruded, samples

130

were weighed to provide the wet mass, freeze-dried and weighed again to

131

determine the dry mass.

132

Short-lived radioisotope measurements and geochronological model

133

calculations follow those presented in Brooks et al. (2015). Brooks et al. (2015)

134

presented several lines of evidence (biological, sedimentological, microbial,

135

radiocarbon, organic geochemical, etc.) that bioturbation was not present in the

136

surface of the cores collected following the DWH. Samples were analyzed by gamma

137

spectrometry on Canberra HPGe (High-Purity Germanium) Coaxial Planar Photon

138

Detectors for total 210Pb (46.5Kev), 214Pb (295 Kev and 351 Kev), and 214Bi (609Kev)

139

activities. Data were corrected for counting time and detector efficiency, as well as

140

for the fraction of the total radioisotope measured yielding activity in dpm g-1

141

(disintegrations per minute per gram).



142

Page 6 of 27

Detector efficiencies (limit of detection) were all 1 dpm cm-2 yr-1, >1.5 dpm

183

cm-2 yr-1, >3.0 dpm cm-2 yr-1) from the pre-DWH to the post-DWH period using a

184

combination of coordinates identified from the ODV, DIVA grid and the Google Earth

185

Pro polygon tool. The >1.5 dpm cm-2 yr-1 and >3.0 dpm cm-2 yr-1 intervals were

186

based on consistent (1.5 dpm cm-2 yr-1) intervals from 0-4.5 dpm cm-2 yr-1. The 4.5

187

dpm cm-2 yr-1 value represents the largest measured differential pre-to-post-DWH

flux were constructed using Ocean Data View (ODV). Polygons were created



188

210Pbxs

189

polygon was also constructed from the coordinates of the sampling sites with

190

increased pre-to-post-DWH 210Pbxs flux to produce the most conservative estimate

191

of spatial coverage, without including DIVA gridding extrapolation.

192

Results

flux at site DWH01 near the DWH wellhead. A least distance-spanning

210Pbxs

193

flux increased in every core from the 1900-1949 to the 1950-2009

194

period (0.11-1.32 dpm cm-2 yr-1, Table 1).

195

from the 1950-2009 to the 2010-2013 period (0.06-4.46 dpm cm-2 yr-1, Table 1). 210Pbxs

196

210Pbxs

flux also increased in every core

flux decreased with distance from the DWH wellhead along three

197

transects (northeast, southeast, southwest) during the 2010-2013 period (Figure 3).

198

There was no decrease in 210Pbxs flux with distance from the DWH wellhead along

199

the same transects during the 1950-2009 period. The 210Pbxs flux during the 1900-1949 and 1950-2009 periods generally

200 201

increased with water depth and higher fluxes generally followed bathymetric

202

features such as the DeSoto Canyon to the east and the Mississippi Valley to the west

203

(Figure 4, Table 2).

204

In total, five polygons were constructed, three in the western portion of the

205

study area and two in the eastern portion (Table 3). In the western portion of the

206

study area, an area of 32,350 km2 had a differential 210Pbxs flux greater than 1.5 dpm

207

cm-2 yr-1, an area of 16,972 km2 had a differential 210Pbxs flux greater than 3 dpm cm-

208

2 yr-1,

209

210Pbxs

210

3). In the eastern portion of the study area, an area of 3,075 km2 had a differential

and an area between sampling stations (minimum span) with differential flux greater than 1.5 dpm cm-2 yr-1 had an area of 11,273 km2 (Figure 5, Table


Page 8 of 27

Page 9 of 27


211

210Pbxs

212

with differential 210Pbxs flux greater than 1.0 dpm cm-2 yr-1 (minimum span) had an

213

area of 1,532 km2 (Figure 5, Table 3).

214

Discussion

215

flux greater than 1 dpm cm-2 yr-1, and an area between sampling stations

The range of total 210Pbxs inventories from this study was slightly higher

216

overall than those previously published. Yeager et al., (2004) reported a range in

217

total 210Pbxs inventories of 21.0-208.8 dpm cm-2 from six sites throughout the nGoM

218

and the 210Pbxs inventories from this study ranged from 34.0-275.1 dpm cm-2 (Table

219

1). Two of the sampling sites (S36, 1849 m water depth; MT3, 985 m water depth)

220

presented by Yeager et al., (2004) were near (21 km and 40 km, respectively) two of

221

the sites sampled in this study (DSH10, MV02). The total 210Pbxs inventories at

222

DSH10 and MV02 were 155.0 (± 0.06 dpm cm-2) and 275.1 (± 0.03 dpm cm-2), while

223

the total 210Pbxs inventories at S36 and MT3 were 108.6 (± 0.12 dpm cm-2) and 208.8

224

(± 0.07 dpm cm-2) respectively. Yeager et al. (2004) used an alpha spectrometry

225

method while this study used a gamma spectrometry method. The errors associated

226

with the different analytical methods are negligible compared to the variability

227

between sites that both Yeager et al. (2004)(21-208 dpm cm-2) and this manuscript

228

(34-275 dpm cm-2) document throughout the gulf. The overall agreement between

229

records over the entire nGoM region is evidence that these datasets are comparable.

230

Again, these comparisons are only used in this manuscript to demonstrate that our

231

data are reasonable with regards to previously published literature in the region,

232

which is quite limited. It is arguable that the overall increase in 210Pbxs inventories



233

from Yeager et al., (2004) to this study could have been caused by the increased

234

210Pbxs

235

flux associated with MOSSFA during and following DWH. Prior to 2010, 210Pbxs flux primarily increased with water depth (Figure 4,

236

Table 2) suggesting that bathymetric features acted as a control of 210Pbxs flux prior

237

to 2010.

238

regions from 1900-1949 and primarily in the Desoto Canyon from 1950-2009

239

(Figure 4). As expected, a deeper water column provided greater 210Pbxs activity for

240

particle scavenging and bathymetric lows may have provided focusing mechanisms

241

for advective transport.

242

210Pbxs

flux was focused in the DeSoto Canyon and Mississippi Valley

The fact that there is not a significant increase in 210Pbxs flux over the entire

243

region from the 1900-1950 to 1950-2009, whereas there is a significant increase

244

from 1950-2009 to 2010-2013, argues that the increased signal is not from natural

245

variability (e.g. Mississippi River) and was in fact caused by DWH, MOSSFA. The

246

pearson correlation (Table 2) further supports that prior to DWH, 210Pbxs flux was

247

primarily determined by water depth. After 2010, the sinking of marine oil snow

248

primarily controlled the distribution of 210Pbxs flux. The decrease in 210Pbxs flux with

249

distance from the DWH wellhead is consistent with MOSSFA centered on the DWH

250

wellhead (Figure 3, Table 2). This decrease in 210Pbxs flux with distance from the

251

wellhead was not apparent in the 1950-2009 time period, which further supports a

252

change in depositional pattern during and after DWH.

253

The spatial extent of MOSSFA, determined by differential 210Pbxs flux between

254

the 1950-2009 period and the 2010-2013 period was primarily focused in two

255

areas: 1) in the western portion of the study area on an east-northeast to west-


Page 10 of 27

Page 11 of 27


256

southwest axis, stretching 230 km to the southwest and 140 km to the northeast of

257

the DWH wellhead, and 2) in the eastern portion of the study area on a 70 km

258

northeast to southwest axis near the DeSoto Canyon (Figure 5).

259

In the area to the west, spatial estimates of MOSSFA ranged from 11,273-

260

32,350 km2 using differential 210Pbxs flux. Estimates of the spatial extent of

261

sedimentary petroleum deposition, based on sedimentary radiocarbon, flocculent

262

sedimentary hopane concentration, flux rates of petroleum compounds, and

263

petroleum compounds in flocculent sediments ranged from 1,300-24,000 km2

264

(Chanton et al., 2015; Valentine et al., 2014; NRDA, 2015; Stout et al., 2015; Stout

265

and German, 2015; Passow and Ziervogel, 2016). Chanton et al., (2015) identified

266

an area of 8,400 km2 primarily to the southwest of the DWH wellhead that was

267

impacted by sedimentary petroleum deposition. Valentine et al., (2014) utilized

268

hopane concentrations in sedimentary flocculent material to constrain an area of

269

3,200 km2 centered on the DWH wellhead. However, the objective of these studies

270

was to identify areas with increased petroleum deposition using petroleum

271

indicators, while the aim of this study was to constrain the total spatial extent of

272

increased flux of flocculent material from the water column. So, it was expected that

273

210Pbxs

274

previous petroleum indicator estimates. Ultimately, the most conservative estimate

275

(11,273 km2), which was based on the minimum span between sampling sites, was

276

most consistent with previous studies that identified the spatial extent of various

277

sedimentary petroleum indicators.

flux would provide a larger estimate of the spatial extent of MOSSFA than the



278

For the eastern extent of this study, spatial estimates of MOSSFA ranged from

279

1,532-3,075 km2 using differential 210Pbxs flux. Again, the most conservative

280

estimate (1,532 km2), based on the minimum span between sampling sites was most

281

consistent with previous studies that identified the spatial extent of sedimentary

282

petroleum indicators (~2,000 km2) near the DeSoto Canyon (Romero et al., 2015;

283

Passow and Ziervogel, 2016). The ~2000 km2 estimate was generated by using GIS

284

to calculate the area of polygons between impacted sites (Passow, pers. comm.).

285

Based on synthetic aperture radar (SAR) data, the maximum daily extent of

286

surface petroleum coverage was 39,600 km2 (NRDA, 2015). The highest estimates

287

(35,425 km2) of the spatial extent of MOSSFA from this study (3,075 km2 >1 dpm

288

cm-2 yr-1 to the east and 32,350 km2 >1.5 dpm cm-2 yr-1 to the west) were less than,

289

but on the same order as the spatial extent of daily surface petroleum coverage, and

290

agreed with findings that MOSSFA affected broad sections of the continental slope

291

and shelf where surface oil occurred (NRDA, 2015; Stout and German, 2015). The

292

eastern and western areas of higher 210Pbxs fluxes identified in this study were also

293

within the extent of the cumulative surface petroleum coverage (87 days, 112,115

294

km2, NRDA, 2015) (Figure 5).

295

Another important consideration was the agreement of the spatial extent of

296

increased 210Pbxs flux with observed MOSSFA impacts to the benthos in the nGoM

297

following the DWH event. Following the DWH event, a 4-10 fold increase in

298

sedimentary mass accumulation rates and a 2-3 fold increase in polycyclic aromatic

299

hydrocarbons was documented in the DeSoto Canyon region (Brooks et al., 2015;

300

Romero et al., 2015). The total organic carbon (TOC) accumulation rates at DSH08


Page 12 of 27

Page 13 of 27


301

and PCB06 increased from 6.3-12.6 gcm-2yr-1 on average prior to the DWH to 91-

302

136 gcm-2yr-1 during 2010 (Romero et al., 2015, Schwing et al., 2015). Respiration

303

of the increased organic carbon flux caused intensifying reducing conditions until

304

2013 (Hastings et al., 2016). Schwing et al. (2015, 2016A) documented an 80-93%

305

decrease in benthic foraminiferal density and a 30-40% decrease in benthic

306

foraminiferal diversity directly related to increased PAH concentrations and

307

intensification of reducing conditions at sites in the DeSoto Canyon region (e.g.

308

DSH08) from 2010-2011. The differential pre-to-post-DWH 210Pbxs flux at DSH08

309

was 2.42 dpm cm-2 yr-1. In the western portion of the study area, Montagna et al.

310

(2013) found that macrofaunal diversity was impacted throughout an area of 148

311

km2 centered around the DWH wellhead. The DWH01 site, less that 1km from the

312

DWH wellhead, differential pre-to-post-DWH 210Pbxs flux was 4.46 dpm cm-2 yr-1.

313

Baguley et al. (2015) also found that meiofaunal diversity was impacted over an

314

area of 406 km2 in two distinct regions; surrounding the DWH wellhead and the

315

Mississippi Valley. The Mississippi Valley area of impact described by Baguley et al.

316

(2015) encompasses the MV02 and SW01 sites from this study. The differential pre-

317

to-post-DWH 210Pbxs flux was 1.57 dpm cm-2 yr-1 at SW01 and 3.83 dpm cm-2 yr-1 at

318

MV02. Increased 210Pbxs flux was documented at each of the sites in the DeSoto

319

canyon, near the DWH wellhead, and in the Mississippi Valley regions where there

320

were corresponding impacts to benthic biological diversity and density. The spatial

321

agreement between these three records of benthic biological impact and increased

322

210Pbxs

323

supporting the use of 210Pbxs flux as a tracer for MOSSFA.

flux measurements provided another corroborative line of evidence



Overall, the use of 210Pbxs flux was successfully utilized as a tracer for DWH-

324 325

related MOSSFA. Two primary depositional areas were identified with a total

326

spatial extent ranging from 12,805-35,425 km2. The primary advantage of using

327

210Pbxs

328

was the ability to constrain the total spatial extent of increased mass flux of

329

flocculent material from the water column, beyond simply the petroleum fraction.

330

Further work is needed, using sedimentary collections beyond 2013, to assess the

331

effects of advective transport and to identify the ultimate depocenters of MOSSFA

332

material.

333

Acknowledgements

334

This research was made possible in part by a grant from the Gulf of Mexico Research

335

Initiative, C-IMAGE, DEEP-C and in part by the British Petroleum/Florida Institute of

336

Oceanography (BP/FIO)-Gulf Oil Spill Prevention, Response, and Recovery Grants

337

Program. The authors also thank the crew of the R/V Weatherbird II for their

338

assistance during the field program. Data are publicly available through the Gulf of

339

Mexico Research Initiative Information & Data Cooperative (GRIIDC) at:

340

http://data.gulfresearchinitiative.org/data/R4.x267.000:0016 (doi:

341

10.7266/N73N21FW).

flux as a complimentary tool in addition to sedimentary petroleum tracers

342 343 344 345 346 347 348 349

References Appleby, P.G.; Oldfield, F. The assessment of 210Pb data from sites with varying sediment accumulation rates. Hydrobiologia, 1983,103: 29–35. Atlas, R.M.; Hazen, T.C. Oil biodegradation and bioremediation: a tale of the two worst spills in U.S. history. Environ. Sci. and Technol., 2011, 45, 6709–6715.


Page 14 of 27

Page 15 of 27


350 351 352 353

Baskaran, M.; Santschi, P.H. Particulate and dissolved 210Pb activities in the shelf and slope regions of the Gulf of Mexico waters. Contin. Shelf Res., 2002, 22: 1493– 1510.

354 355 356 357

Baguley, J.; Montagna, P.; Cooksey, C.; Hyland, J.; Bang, H.; Morrison, C.; Ricci, M. Community response of deep-sea soft-sediment metazoan meiofauna to the Deepwater Horizon blowout and oil spill. Mar. Ecol. Prog. Ser., 2015, 528, 127–140. http://doi.org/10.3354/meps11290

358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380

Binford, M.W. Calculation and uncertainty analysis of 210Pb dates for PIRLA project lake sediment cores. J. Paleolimno., 1990, 3: 253–267. Brooks, G.R.; Larson, R.A.; Schwing, P.T.; Flower, B.P.; Hollander, D.J.; Romero, I.C.; Moore, C.; Reichart, G.J.; Jilbert, T.; Hastings. Sediment Pulse in the NE Gulf of Mexico Following the 2010 DWH Blowout. PLoS ONE, 2015, 10(7): e0132341. doi:10.1371/journal.pone.0132341 Chanton, J.; Zhao, T.; Rosenheim, B. E.; Joye, S.; Bosman, S.; Brunner, C.; et al. Using Natural Abundance Radiocarbon To Trace the Flux of Petrocarbon to the Seafloor Following the Deepwater Horizon Oil Spill. Environ. Sci. Technol., 2015, 49 (2), 847– 854, http://doi.org/10.1021/es5046524 Cutshall, N.H.; Larsen, I.L.; Olsen, C.R. Direct analysis of 210Pb in sediment samples: self-absorption corrections. Nuc. Inst. and Meth., 1983, 206: 309–312. Daly, K.L., Passow, U., Chanton, J., Hollander, D. Assessing the impacts of oil associated marine snow formation and sedimentation during and after the Deepwater Horizon oil spill. Anthropocene, 2016, 12, 18-33. http://dx.doi.org/10.1016/j.ancene.2016.01.006 ERMA (Environmental Response Management Application). ERMA Deepwater Gulf Response web application; http://gomex.erma.noaa.gov/.

381 382 383

Gordon, E.,; Goñi, M. Controls on the distribution and accumulation of terrigenous organic matter in sediments from the Mississippi and Atchafalaya river margin. Mar. Chem., 2004, 92, 331–352. http://doi.org/10.1016/j.marchem.2004.06.035

384 385 386 387 388 389 390 391

Hastings, D.W.; Schwing, P.T.; Brooks, G.R.; Larson, R.A.; Morford, J.L.; Roeder, T.; Quinn, K.D.; Romero, I.C.; Hollander, D. J. Changes in sediment redox conditions following the BP DWH Blowout event. DSR II, 2016, 129, 176-178, doi:10.1016/j.dsr2.2014.12.009. Holmes, C.W. Short-lived isotopes in sediments (a tool for assessing sedimentary dynamics). USGS open file report, 2001.



392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425

Hussain N.; Kim G.; Church T.M.; Carey W. A simplified technique for gammaspectrometric analysis of 210Pb in sediment samples. Appl. Radiat. Isot., 1996, 47: 473–477. Kitto, M.E. Determination of photon self-absorption corrections for soil samples, Appl. Radiat. Isot., 1991, 42, 835-839. Montagna P.A.; Baguley J.G.; Cooksey C.; Hartwell I.; Hyde L.J.; Hyland, J.L.; Kalke R.D.; Kracker, L.M.; Reuscher, M.; Rhodes, A.C.E. Deep-Sea Benthic Footprint of the Deepwater Horizon Blowout. PLoS ONE, 2013, 8(8): e70540. doi:10.1371/journal.pone.0070540 Muhammad, Z.; Bentley, S.J.; Febo, L.A.; Droxler, A.W.; Dickens, G.R.; Peterson, L.C. and Opdyke, B.N. Excess 210Pb inventories and fluxes along the continental slope and basins of the Gulf of Papua, J. Geophys. Res., 2008, 113, F01S17, doi:10.1029/2006JF000676. Draft Programmatic Environmental Impact Statement; Natural Resource Damage Assessment, National Ocean Service, National Oceanic and Atmospheric Administration, 2015; http://www.Gulfspillrestoration.noaa.gov/wpcontent/uploads/Chapter-4_Injury-to-Natural-Resources.pdf. Passow, U. and K. Ziervogel. Marine snow sedimented oil released during the Deepwater Horizon spill. Oceanography, 2016, 29(3):118–125, http://dx.doi.org/10.5670/oceanog.2016.76. Passow, U.; Ziervogel, K.; Aper, V.; Diercks, A. Marine snow formation in the aftermath of the Deepwater Horizon oil spill in the Gulf of Mexico. Environ. Res. Lett., 2012, 7, 035301. Romero, I.C.; Schwing, P.T.; Brooks, G.R.; Larson, R.A.; Hastings, D.W.; Ellis G.; Goddard, E.A.; Hollander, D.J. Hydrocarbons in Deep Sea Sediments Following the 2010 Deepwater Horizon Blowout in the Northeast Gulf of Mexico. PLoS ONE, 2015, 10(5): e0128371. doi: 10.1371/journal.pone.0128371

426 427 428 429

Sampere, T. P.; Bianchi, T. S. & Allison, M. A. Historical changes in terrestrially derived organic carbon inputs to Louisiana continental margin sediments over the past 150 years. J. Geophys. Res., 2011, 116(G1), G01016. http://doi.org/10.1029/2010JG001420

430 431 432 433 434 435

Schwing, P.T.; O’Malley, B.J.; Romero, I.C.; Martínez-Colón, M.; Hastings, D.W.; Glabach, M.A.; Hladky, E.M.; Greco, A., Hollander, D.J. Characterizing the variability of benthic foraminifera in the northeastern Gulf of Mexico following the Deepwater Horizon event (2010-2012). Environ. Sci. & Poll. Res., 2016A, DOI 10.1007/s11356016-7996-z.


Page 16 of 27

Page 17 of 27

436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462


Schwing, P.T., Romero, I.C., Larson, R.A., O'Malley, B.J., Fridrik, E.E., Goddard, E.A., Brooks, G.R., Hastings, D.W., Rosenheim, B.E., Hollander, D.J., Grant, G., Mulhollan, J. Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod. J. Vis. Exp., 2016B (114), e54363, doi:10.3791/54363. Schwing, P.T.; Romero, I.C.; Brooks, G.R.; Hastings, D.W.; Larson, R.A.; Hollander, D.J. A Decline in Deep-Sea Benthic Foraminifera Following the Deepwater Horizon Event in the Northeastern Gulf of Mexico. PLoS ONE, 2015, 10(3): e0120565. doi:10.1371/journal.pone.0120565. Stout, A.S. and German, C.R. Characterization and Flux of Marine Oil Snow into the Visca Knoll (Lophelia Reef) Area due to the Deepwater Horizon Oil Spill. US Department of the Interior, Deepwater Horizon Response & Restoration, Administrative Record, 2015, 34, http://pub-dwhdatadiver.orr.noaa. gov/dwh-ardocuments/946/DWH-AR0039084.pdf. Stout, A.S.; Rouhani, S.; Liu, B. and Oehrig, J. Spatial Extent (“Footprint”) and Volume of Macondo Oil Found on the Deep-Sea Floor Following the Deepwater Horizon Oil Spill. US Department of the Interior, Deepwater Horizon Response & Restoration, Administrative Record, 2015, DWH-AR0260244, 29, http://pubdwhdatadiver.orr.noaa.gov/ dwh-ar-documents/946/DWH-AR0260244.pdf. Valentine, D. L.; Fisher, G. B.; Bagby, S. C.; Nelson, R. K.; Reddy, C. M. & Sylva, S. P. Fallout plume of submerged oil from Deepwater Horizon, PNAS, 2014, 1–6. doi:10.1073/pnas.1414873111 Yeager, K.M.; Santschi, P.H.; Rowe, G.T. Sediment accumulation and radionuclide 239,240

210

234

463 464

inventories ( Pu, Pb and Th) in the northern Gulf of Mexico, as influenced by organic matter and macrofaunal density. Mar. Chem. 2004, 91: 1–14.

465 466 467 468 469 470

Ziervogel, K.; Mckay, L.; Rhodes, B.; Osburn, C. L.; Dickson-Brown, J.; Arnosti, C.; Teske, A. Microbial activities and dissolved organic matter dynamics in oilcontaminated surface seawater from the Deepwater Horizon oil spill site. PLoS One, 2012, 7(4), e34816.

471 472 473 474 475 476 477



478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504

Figure Captions Figure 1: Coring site locations in the northern Gulf of Mexico. (For reference: DWH01 is less than 1 km from the Deepwater Horizon wellhead).

Figure 2: Graphic depiction of the decay correction method and integration of 210Pbxs flux during each time period. The yellow bars represent the 210Pbxs activity corrected to the surface activity (time of collection) for each sample increment. The base figure of idealized supported and unsupported (excess) 210Pb was adapted from Holmes, 2001 and the inventories were calculated using the method described by Baskaran and Santschi, 2002. Figure 3: Plots of 210Pbxs flux with distance (left to right) from the DWH wellhead along three transects (A. southeast, B. northeast, and C. southwest) for the pre-DWH (1950-2009, light gray bars) and post-DWH (2010-2013, dark gray bars) time periods. Figure 4: DIVA gridded contour maps of 210Pbxs flux for 1900-1949 (A), 1950-2009 (B), and 2010-2013 (C). The star represents the location of the DWH wellhead. Figure 5: A DIVA gridded contour map of the differential (difference of post-DWH and pre-DWH values) 210Pbxs flux. Polygons were constructed to determine the spatial extent of differential 210Pbxs flux. The polygons surround differential 210Pbxs flux greater than 3 dpm cm-2 yr-1 (blue), 1.5 dpm cm-2 yr-1 (black) and a minimum span between coring sites (red) in the western extent of the study area and greater than 1 dpm cm-2 yr-1 (black) and minimum span between coring sites (red) in the eastern extent of the study area. The gray overlay is the cumulative total extent of surface petroleum coverage (ERMA, 2015). The star represents the location of the DWH wellhead.

505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520


Page 18 of 27

Page 19 of 27

521 522 523 524


Tables Table 1: Core site names, collection date, location, water depth, distance from the Deepwater Horizon wellhead, 210Pbxs flux for each time period (1900-1949, 1950-2009, 2010-2013) and the total 210Pbxs inventory. 210Pb

-2

xs

-1

Flux (dpm cm yr )

Longitude

Water Depth (m)

Distance from DWH (km)

20102013

19502009

19001949

Total Pbxs Inventory -2 (dpm cm )

29.66

-86.33

108

222

0.77

0.26

0.06

42.45

29.41

-86.58

302

188

2.83

1.06

0.68

59.26

10-Nov

29.3

-86.68

400

177

0.95

0.37

0.23

68.28

10-Nov

29.17

-86.81

504

160

3.06

0.83

0.37

85.44

MC06

10-Nov

29.08

-86.91

600

148

2.02

0.58

0.2

59.57

MC07

10-Nov

29.39

-86.75

400

175

1.47

0.52

0.32

43.49

MC08

10-Nov

29.49

-86.87

404

168

2.03

1.03

0.28

79.29

MC09

10-Nov

29.22

-86.64

406

177

1.48

0.58

0.35

45.95

MC10

10-Nov

29.07

-86.56

399

183

1.18

0.46

0.26

65.20

DSH07

10-Dec

29.27

-87.76

399

83

2.87

1.29

0.26

112.64

PCB06

10-Dec

29.13

-87.26

1043

117

1.17

0.79

0.44

85.02

DSH08

11-Feb

29.12

-87.87

1143

63

3.4

0.98

0.34

118.49

DSH10

11-Feb

28.98

-87.89

1520

54

2.76

2.2

0.88

152.97

PCB08

11-Feb

28.9

-87.16

900

120

0.86

0.41

0.17

54.50

PCB09

11-Feb

28.86

-87.21

1000

116

1.54

0.92

0.37

69.50

PCB10

11-Feb

28.82

-87.27

1100

108

2.41

1.71

0.48

64.43

NT150

11-Jun

28.53

-85.2

150

312

0.75

0.35

0.06

36.70

NT200

11-Jun

28.4

-85.4

233

290

0.93

0.63

0.31

41.99

NT300

11-Jun

28.31

-85.57

306

277

1.56

0.66

0.34

40.55

NT400

11-Jun

28.23

-85.65

400

275

1.06

0.36

0.26

34.03

NT1200

11-Jun

27.97

-86.03

1200

246

1.81

1.26

0.76

61.58

ST1050

11-Jun

27.04

-85.09

1047

376

1.17

1.11

0.33

35.09

Date Collected (YY-MMM)

Latitude

MC01

10-Nov

MC03

10-Nov

MC04 MC05

Site Name

210

PCB11

11-Sep

28.8

-87.31

1200

103

3.13

1.01

0.31

70.88

NE01

11-Sep

28.79

-88.26

1300

13

3.51

0.86

0.53

93.41

DWH01

11-Sep

28.74

-88.39

1550

1

5.08

0.62

0.25

115.25

SW01

12-Apr

28.22

-89.07

1151

92

2.73

1.16

0.33

133.01

SW03

12-Apr

28.58

-88.8

1200

45

3.17

1.05

0.18

139.24

MV02

12-Aug

28.49

-89.78

550

140

4.3

0.47

0.37

275.11

SL5100

12-Oct

28.55

-85.37

186

296

1.55

0.6

0.22

40.66

SE02

12-Oct

28.36

-86.94

977

142

2.12

1.69

0.64

55.47

HC01

13-Aug

28.37

-90.52

45

212

1.13

0.31

0.09

47.92

HC03

13-Aug

28.22

-90.41

72

207

3.16

0.74

0.28

136.18

525 526



527 528

Table 2: Pearson correlation table of 210Pbxs flux for each time-period with water depth and the inverse of the distance from the DWH wellhead. Note: P < 0.05 is significant. Time Period

529 530 531 532 533 534

Page 20 of 27

Water Depth 2

Inverse Distance from DWH 2

r

R

p

r

R

p

2010+

0.47

0.22

0.01

0.67

0.45

2.73E-05

1950-2009

0.61

0.37

2.35E-04

0.36

0.13

0.04

1900-1950

0.50

0.25

2.20E-03

0.23

0.05

0.21

Table 3: The location of each polygon outline point and polygon area for the three polygons in the western (West) extent of the study area (>3 dpm cm-2 yr-1, >1.5 dpm cm-2 yr-1, and minimum span) and two polygons in the eastern (East) extent of the study area (>1 dpm cm-2 yr-1 and minimum span). Polygon and 2 Site Name Latitude Longitude Area (km )

West -2

>3 dpm cm yr

-1

16,972 29.46

-88.06

29.07

-88.18

28.51

-88.31

28.65

-89.03

28.06

-89.59

28.06

-90.36

29.09

-90.02

29.21

-89.77

29.03

-89.08

29.68

-87.42

28.31

-87.91

28.04

-88.97

28.06

-90.42

28.19

-90.64

28.37

-90.52

29.09

-90.49

29.10

-90.22

29.25

-89.82

29.00

-89.20

DSH07

29.27

-87.76

DSH10

28.98

-87.89

SW01

28.22

-89.07

SW03

28.58

-88.80

HC01

28.37

-90.52

HC03

28.22

-90.41

-2

>1.5 dpm cm yr

HC01

-1

32,350

Minimum Span

11,273


Page 21 of 27


East -2

>1 dpm cm yr

-1

3,075 29.60

-86.64

29.38

-86.34

28.87

-86.85

29.22

-87.12

Minimum Span

1,532

MC03

29.41

-86.58

MC10

29.07

-86.56

MC06

29.08

-86.91

MC07

29.39

-86.75

535 536



TOC_Abstract Art 279x215mm (300 x 300 DPI)


Page 22 of 27

Page 23 of 27


Figure 1: Coring site locations in the northern Gulf of Mexico. (For reference: DWH01 is less than 1 km from the Deepwater Horizon wellhead). 279x215mm (300 x 300 DPI)



Figure 2: Graphic depiction of the decay correction method and integration of 210Pbxs flux during each time period. The yellow bars represent the 210Pbxs activity corrected to the surface activity (time of collection) for each sample increment. The base figure of idealized supported and unsupported (excess) 210Pb was adapted from Holmes, 2001 and the inventories were calculated using the method described by Baskaran and Santschi, 2002. 279x215mm (300 x 300 DPI)


Page 24 of 27

Page 25 of 27


Figure 3: Plots of 210Pbxs flux with distance (left to right) from the DWH wellhead along three transects (A. southeast, B. northeast, and C. southwest) for the pre-DWH (1950-2009, light gray bars) and post-DWH (2010-2013, dark gray bars) time periods. 279x215mm (300 x 300 DPI)



Figure 4: DIVA gridded contour maps of 210Pbxs flux for 1900-1949 (A), 1950-2009 (B), and 2010-2013 (C). The star represents the location of the DWH wellhead. 279x215mm (300 x 300 DPI)


Page 26 of 27

Page 27 of 27


Figure 5: A DIVA gridded contour map of the differential (difference of post-DWH and pre-DWH values) 210Pbxs flux. Polygons were constructed to determine the spatial extent of differential 210Pbxs flux. The polygons surround differential 210Pbxs flux greater than 3 dpm cm-2 yr-1 (blue), 1.5 dpm cm-2 yr-1 (black) and a minimum span between coring sites (red) in the western extent of the study area and greater than 1 dpm cm-2 yr-1 (black) and minimum span between coring sites (red) in the eastern extent of the study area. The gray overlay is the cumulative total extent of surface petroleum coverage (ERMA, 2015). The star represents the location of the DWH wellhead. 279x215mm (300 x 300 DPI)


Constraining the spatial extent of Marine Oil Snow Sedimentation and

Recommend Documents