@article {Prouty2016,
	title = {{Insights into methane dynamics from analysis of authigenic carbonates and chemosynthetic mussels at newly-discovered Atlantic Margin seeps}},
	journal = {Earth and Planetary Science Letters},
	volume = {449},
	year = {2016},
	pages = {332{\textendash}344},
	abstract = {The recent discovery of active methane venting along the US northern and mid-Atlantic margin represents a new source of global methane not previously accounted for in carbon budgets from this region. However, uncertainty remains as to the origin and history of methane seepage along this tectonically inactive passive margin. Here we present the first isotopic analyses of authigenic carbonates and methanotrophic deep-sea mussels, Bathymodiolus sp., and the first direct constraints on the timing of past methane emission, based on samples collected at the upper slope Baltimore Canyon (\~{}385 m water depth) and deepwater Norfolk (\~{}1600 m) seep fields within the area of newly-discovered venting. The authigenic carbonates at both sites were dominated by aragonite, with an average View the MathML source$δ$C13 signature of -47{\textperthousand}-47{\textperthousand}, a value consistent with microbially driven anaerobic oxidation of methane-rich fluids occurring at or near the sediment{\textendash}water interface. Authigenic carbonate U and Sr isotope data further support the inference of carbonate precipitation from seawater-derived fluids rather than from formation fluids from deep aquifers. Carbonate stable and radiocarbon (View the MathML source$δ$C13 and View the MathML source$Δ$C13) isotope values from living Bathymodiolus sp. specimens are lighter than those of seawater dissolved inorganic carbon, highlighting the influence of fossil carbon from methane on carbonate precipitation. U{\textendash}Th dates on authigenic carbonates suggest seepage at Baltimore Canyon between 14.7{\textpm}0.6 ka14.7{\textpm}0.6 ka to 15.7{\textpm}1.6 ka15.7{\textpm}1.6 ka, and at the Norfolk seep field between 1.0{\textpm}0.7 ka1.0{\textpm}0.7 ka to 3.3{\textpm}1.3 ka3.3{\textpm}1.3 ka, providing constraint on the longevity of methane efflux at these sites. The age of the brecciated authigenic carbonates and the occurrence of pockmarks at the Baltimore Canyon upper slope could suggest a link between sediment delivery during Pleistocene sea-level lowstand, accumulation of pore fluid overpressure from sediment compaction, and release of overpressure through subsequent venting. Calculations show that the Baltimore Canyon site probably has not been within the gas hydrate stability zone (GHSZ) in the past 20 ka, meaning that in-situ release of methane from dissociating gas hydrate cannot be sustaining the seep. We cannot rule out updip migration of methane from dissociation of gas hydrate that occurs farther down the slope as a source of the venting at Baltimore Canyon, but consider that the history of rapid sediment accumulation and overpressure may play a more important role in methane emissions at this site.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	doi = {10.1016/j.epsl.2016.05.023},
	author = {Prouty, N G and Sahy, D and Ruppel, C D and Roark, E B and Condon, D and Brooke, S and Ross, S W and Demopoulos, A W J}
}
@article {White2012,
	title = {{Impact of the Deepwater Horizon oil spill on a deep-water coral community in the Gulf of Mexico}},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {109},
	number = {50},
	year = {2012},
	month = {dec},
	pages = {20303{\textendash}20308},
	abstract = {To assess the potential impact of the Deepwater Horizon oil spill on offshore ecosystems, 11 sites hosting deep-water coral communities were examined 3 to 4 mo after the well was capped. Healthy coral communities were observed at all sites {\textgreater}20 km from the Macondo well, including seven sites previously visited in September 2009, where the corals and communities appeared unchanged. However, at one site 11 km southwest of the Macondo well, coral colonies presented widespread signs of stress, including varying degrees of tissue loss, sclerite enlargement, excess mucous production, bleached commensal ophiuroids, and covering by brown flocculent material (floc). On the basis of these criteria the level of impact to individual colonies was ranked from 0 (least impact) to 4 (greatest impact). Of the 43 corals imaged at that site, 46{\%} exhibited evidence of impact on more than half of the colony, whereas nearly a quarter of all of the corals showed impact to {\textgreater}90{\%} of the colony. Additionally, 53{\%} of these corals{\textquoteright} ophiuroid associates displayed abnormal color and/or attachment posture. Analysis of hopanoid petroleum biomarkers isolated from the floc provides strong evidence that this material contained oil from the Macondo well. The presence of recently damaged and deceased corals beneath the path of a previously documented plume emanating from the Macondo well provides compelling evidence that the oil impacted deep-water ecosystems. Our findings underscore the unprecedented nature of the spill in terms of its magnitude, release at depth, and impact to deep-water ecosystems.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {0027-8424},
	doi = {10.1073/pnas.1118029109},
	author = {White, H K and Hsing, P-Y and Cho, W and Shank, T M and Cordes, E E and Quattrini, A M and Nelson, R K and Camilli, R and Demopoulos, A W J and German, C R and Brooks, J M and Roberts, H H and Shedd, W and Reddy, C M and Fisher, C R}
}
