scholarly journals Isotopic composition of sinking particles: Oil effects, recovery and baselines in the Gulf of Mexico, 2010–2015

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
Jeffrey P. Chanton ◽  
Sarah L.C. Giering ◽  
Samantha H. Bosman ◽  
Kelsey L. Rogers ◽  
Julia Sweet ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Reference Site ◽  
Recovery Period ◽  
Hydrocarbon Composition ◽  
Sediment Traps ◽  
Isotopic Signatures ◽  
Anthropogenic Inputs ◽  
Sinking Particles ◽  
Spill Site ◽  
Seep Site

The extensive release of oil during the 2010 Deepwater Horizon spill in the northern Gulf of Mexico perturbed the pelagic ecosystem and associated sinking material. To gauge the recovery and post-spill baseline sources, we measured Δ14C, δ13C and δ34S of sinking particles near the spill site and at a reference site and natural seep site. Particulates were collected August 2010–April 2016 in sediment traps moored at sites with depths of 1160–1660 m. Near the spill site, changes in Δ14C indicated a 3-year recovery period, while δ34S indicated 1–2 years, which agreed with estimates of 1–2 years based on hydrocarbon composition. Under post-spill baseline conditions, carbon inputs to sinking particulates in the northern Gulf were dominated by surface marine production (80–85%) and riverine inputs (15–20%). Near the spill site, Δ14C values were depleted in October 2010 (–140 to –80‰), increasing systematically by 0.07 ± 0.02‰ day–1 until July 2013 when values reached –3.2 ± 31.0‰. This Δ14C baseline was similar to particulates at the reference site (3.8 ± 31.1‰). At both sites, δ13C values stayed constant throughout the study period (–21.9 ± 0.5‰ and –21.9 ± 0.9‰, respectively). δ34S near the spill site was depleted (7.4 ± 3.1‰) during October 2010–September 2011, but enriched (16.9 ± 2.0‰) and similar to the reference site (16.2 ± 3.1‰) during November 2012–April 2015. At the seep site, Δ14C values were –21.7 ± 45.7‰ except during August 2012–January 2013 when a significant Δ14C depletion of –109.0 ± 29.1‰ was observed. We interpret this depletion period, also observed in δ13C data, as caused by the incorporation of naturally seeped oil into sinking particles. Determination of post-spill baselines for these isotopic signatures allows for evaluation of anthropogenic inputs in future.

scholarly journals The ecosystem baseline for particle flux in the Northern Gulf of Mexico

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
S.L.C. Giering ◽  
B. Yan ◽  
J. Sweet ◽  
V. Asper ◽  
A. Diercks ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Mississippi River ◽  
Large Fraction ◽  
Combustion Products ◽  
Sediment Traps ◽  
Sedimentation Rates ◽  
Northern Gulf Of Mexico ◽  
Sinking Particles ◽  
Spilled Oil ◽  
Seep Site

Response management and damage assessment during and after environmental disasters such as the Deepwater Horizon (DWH) oil spill require an ecological baseline and a solid understanding of the main drivers of the ecosystem. During the DWH event, a large fraction of the spilled oil was transported to depth via sinking marine snow, a routing of spilled oil unexpected to emergency response planners. Because baseline knowledge of particle export in the Northern Gulf of Mexico and how it varies spatially and temporally was limited, we conducted a detailed assessment of the potential drivers of deep (~1400 m depth) particle fluxes during 2012–2016 using sediment traps at three contrasting sites in the Northern Gulf of Mexico: near the DWH site, at an active natural oil seep site, and at a site considered typical for background conditions. The DWH site, located ~70 km from the Mississippi River Delta, showed flux patterns that were strongly linked to the Mississippi nitrogen discharge and an annual subsequent surface bloom. Fluxes carried clear signals of combustion products, which likely originated from pyrogenic sources that were transported offshore via the Mississippi plume. The seep and reference sites were more strongly influenced by the open Gulf of Mexico, did not show a clear seasonal flux pattern, and their overall sedimentation rates were lower than those at the DWH site. At the seep site, based on polycyclic aromatic hydrocarbon data, we observed indications of three different pathways for “natural” oiled-snow sedimentation: scavenging by sinking particles at depth, weathering at the surface before incorporation into sinking particles, and entry into the food web and subsequent sinking in form of detritus. Overall, sedimentation rates at the three sites were markedly different in quality and quantity owing to varying degrees of riverine and oceanic influences, including natural seepage and contamination by combustion products.

Impacts of meso and submesoscale dynamics on the horizontal dispersion of sinking particles from the surface to the deep ocean

2020 ◽  
Author(s):  
Lu Wang ◽  
Jonathan Gula ◽  
Jeremy Collin ◽  
Laurent Memery
Keyword(s):  
General Structure ◽  
Finite Size ◽  
Deep Ocean ◽  
Sediment Traps ◽  
Horizontal Distribution ◽  
Particle Dispersion ◽  
Small Scale ◽  
Transport Pathways ◽  
Horizontal Dispersion ◽  
Sinking Particles

<p>Energetic eddy fields generated by meso and submesoscale dynamics induce tridimensional particle transport pathways, which complicate the interpretation of observed Particulate Organic Carbon (POC) fluxes using sediment traps. It is therefore of importance to understand how horizontal dispersion of particles is structured by these dynamics from surface to depth. In this modelling study, we use a Lagrangian method to backtrack sinking particles collected at various depths ranging from 500 m to 4700 m at the PAP (Porcupine Abyssal Plain) site. Particle trajectories are computed using high-resolution simulations of the Regional Ocean Modelling System (ROMS). Our results show that the horizontal distribution of particles with sinking velocities below 100 m d<sup>-1</sup> presents a large small-scale heterogeneity. Mesoscale eddies act to define the general structure of particle patches while submesoscale features shape particle distributions through convergence/divergence processes. Distribution patterns of particles tracked from different depths suggest regime shifts of particle dispersion between subsurface layers. To identify and quantify these regimes, we perform 2d experiments at specific depths from 100 m to 4000 m and relate the Lagrangian statistics to the characteristics of the different dynamical regimes identified using vertical profiles of eddy energy and Finite Size Lyapunov Exponents (FSLE) approach.                                                                                                                                                               </p>

scholarly journals Interannual variability of pteropod shell weights in the high-CO<sub>2</sub> Southern Ocean

2008 ◽  
Vol 5 (6) ◽  
pp. 4453-4480 ◽  
Author(s):  
D. Roberts ◽  
W. R. Howard ◽  
A. D. Moy ◽  
J. L. Roberts ◽  
T. W. Trull ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Co2 Enrichment ◽  
Sediment Traps ◽  
Carbonate Chemistry ◽  
Shell Weight ◽  
Data Set ◽  
Anthropogenic Inputs ◽  
Limacina Helicina ◽  
Decadal Trend ◽  
Ocean Ecosystems

Abstract. Anthropogenic inputs of CO2 are altering ocean chemistry and may alter the role of marine calcifiers in ocean ecosystems. CO2 emissions over the coming centuries may produce changes in ocean pH not seen for millions of years. Laboratory evidence has shown decreased calcification in some species of coccolithophores, foraminifera, corals and pteropods in response to CO2 enrichment. However, in situ observations of calcification in marine organisms are limited, especially for the aragonitic pteropods. This group of pelagic molluscs are likely to be more sensitive to changes in carbonate chemistry than calcite producers such as foraminifera and coccolithophores. Here we present observations of pteropod shell-weight and flux from 1997–2006 in sediment traps deployed at 47° S, 142° E at 2000 meters below sea surface in the Southern Ocean. A decadal trend of –1.17±0.47 μg yr−1 (P=0.02) in mean shell weight in the pteropod Limacina helicina antarctica forma antarctica suggests a small but detectable reduction in calcification. Gaps in the data make it difficult to state with certainty the significance of the trend. However, this data set represents the first attempt to estimate interannual variations in pteropod calcification and establish a benchmark against which future impacts of ocean acidification may be detected. Contributions of Limacina helicina antarctica morphotypes to the total pteropod flux were also reduced over the decade. We suggest these small though discernible trends are due to changing carbonate chemistry in the Subantarctic, as other oceanographic variables show no clear decadal trends. With CO2 continuing to enter the ocean such impacts on pteropods and other marine calcifiers could result in changes to the distribution of species and the structure of Southern Ocean ecosystems.

scholarly journals Hydrocarbon migration pathway and methane budget for a Gulf of Mexico natural seep site: Green Canyon 600

2020 ◽  
Vol 545 ◽  
pp. 116411 ◽  
Author(s):  
C. Johansen ◽  
L. Macelloni ◽  
M. Natter ◽  
M. Silva ◽  
M. Woosley ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Hydrocarbon Migration ◽  
Migration Pathway ◽  
Methane Budget ◽  
Seep Site

Time-Based Correlation of Biogenic, Lithogenic and Authigenic Sediment Components with Anthropogenic Inputs in the Gulf of Mexico NECOP Study Area

Estuaries ◽  
1994 ◽  
Vol 17 (4) ◽  
pp. 873 ◽  
Author(s):  
Terry A. Nelsen ◽  
Pat Blackwelder ◽  
Terri Hood ◽  
Brent McKee ◽  
Nidia Romer ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Anthropogenic Inputs

scholarly journals Historical trace element accumulation in marine sediments from the Tamaulipas shelf, Gulf of Mexico: An assessment of natural vs anthropogenic inputs

2018 ◽  
Vol 622-623 ◽  
pp. 325-336 ◽  
Author(s):  
Omar Celis-Hernandez ◽  
Leticia Rosales-Hoz ◽  
Andrew B. Cundy ◽  
Arturo Carranza-Edwards ◽  
Ian W. Croudace ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Trace Element ◽  
Marine Sediments ◽  
Anthropogenic Inputs ◽  
Element Accumulation ◽  
Trace Element Accumulation

scholarly journals Biological composition and microbial dynamics of sinking particulate organic matter at abyssal depths in the oligotrophic open ocean

2019 ◽  
pp. 201903080 ◽  
Author(s):  
Dominique Boeuf ◽  
Bethanie R. Edwards ◽  
John M. Eppley ◽  
Sarah K. Hu ◽  
Kirsten E. Poff ◽  
...  
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Deep Sea ◽  
Deep Ocean ◽  
Sediment Traps ◽  
Rrna Gene ◽  
North Pacific Subtropical Gyre ◽  
Near Surface ◽  
The North ◽  
Sinking Particles

Sinking particles are a critical conduit for the export of organic material from surface waters to the deep ocean. Despite their importance in oceanic carbon cycling and export, little is known about the biotic composition, origins, and variability of sinking particles reaching abyssal depths. Here, we analyzed particle-associated nucleic acids captured and preserved in sediment traps at 4,000-m depth in the North Pacific Subtropical Gyre. Over the 9-month time-series, Bacteria dominated both the rRNA-gene and rRNA pools, followed by eukaryotes (protists and animals) and trace amounts of Archaea. Deep-sea piezophile-like Gammaproteobacteria, along with Epsilonproteobacteria, comprised >80% of the bacterial inventory. Protists (mostly Rhizaria, Syndinales, and ciliates) and metazoa (predominantly pelagic mollusks and cnidarians) were the most common sinking particle-associated eukaryotes. Some near-surface water-derived eukaryotes, especially Foraminifera, Radiolaria, and pteropods, varied greatly in their abundance patterns, presumably due to sporadic export events. The dominance of piezophile-like Gammaproteobacteria and Epsilonproteobacteria, along with the prevalence of their nitrogen cycling-associated gene transcripts, suggested a central role for these bacteria in the mineralization and biogeochemical transformation of sinking particulate organic matter in the deep ocean. Our data also reflected several different modes of particle export dynamics, including summer export, more stochastic inputs from the upper water column by protists and pteropods, and contributions from sinking mid- and deep-water organisms. In total, our observations revealed the variable and heterogeneous biological origins and microbial activities of sinking particles that connect their downward transport, transformation, and degradation to deep-sea biogeochemical processes.

scholarly journals Deepwater Horizon oil spill impacts on sea turtles could span the Atlantic

2015 ◽  
Vol 11 (12) ◽  
pp. 20150596 ◽  
Author(s):  
Nathan F. Putman ◽  
F. Alberto Abreu-Grobois ◽  
Iñaky Iturbe-Darkistade ◽  
Emily M. Putman ◽  
Paul M. Richards ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Oil Spill ◽  
Ocean Circulation ◽  
Sea Turtles ◽  
Circulation Model ◽  
Deepwater Horizon ◽  
The United States ◽  
Deepwater Horizon Oil Spill ◽  
Spill Site ◽  
Kemp's Ridley

We investigated the extent that the 2010 Deepwater Horizon oil spill potentially affected oceanic-stage sea turtles from populations across the Atlantic. Within an ocean-circulation model, particles were backtracked from the Gulf of Mexico spill site to determine the probability of young turtles arriving in this area from major nesting beaches. The abundance of turtles in the vicinity of the oil spill was derived by forward-tracking particles from focal beaches and integrating population size, oceanic-stage duration and stage-specific survival rates. Simulations indicated that 321 401 (66 199–397 864) green ( Chelonia mydas ), loggerhead ( Caretta caretta ) and Kemp's ridley ( Lepidochelys kempii ) turtles were likely within the spill site. These predictions compared favourably with estimates from in-water observations recently made available to the public (though our initial predictions for Kemp's ridley were substantially lower than in-water estimates, better agreement was obtained with modifications to mimic behaviour of young Kemp's ridley turtles in the northern Gulf). Simulations predicted 75.2% (71.9–76.3%) of turtles came from Mexico, 14.8% (11–18%) from Costa Rica, 5.9% (4.8–7.9%) from countries in northern South America, 3.4% (2.4–3.5%) from the United States and 1.6% (0.6–2.0%) from West African countries. Thus, the spill's impacts may extend far beyond the current focus on the northern Gulf of Mexico.

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