The hadal zone is an important and heterogeneous sink of black carbon in the ocean

Zhang, Xi; Xu, Yunping; Xiao, Wenjie; Zhao, Meixun; Wang, Zicheng; Wang, Xuchen; Xu, Liping; Luo, Min; Li, Xinxin; Fang, Jiasong; Fang, Yin; Wang, Yasong; Oguri, Kazuta; Wenzhöfer, Frank; Rowden, Ashley A.; Mitra, Siddhartha; Glud, Ronnie N.

doi:10.1038/s43247-022-00351-7

Cited by 17 publications

(24 citation statements)

References 66 publications

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“…The 14 C ages of PyC are usually much older than the ages of TOC in sediments of the other marine environments, as shown in Figure 4. The ranges of the 14 C ages of PyC in the sediments of the Arctic Ocean (Ren et al., 2019), East China Sea (Wang & Li, 2007), Atacama Trench and several other trenches in the North Pacific Ocean (Zhang et al., 2022), Santa Monica Basin (Masiello & Druffel, 2003), Northeastern Pacific and Southern Ocean (Masiello & Druffel, 1998) were all significantly older than the ages of TOC. All showed trends that were opposite to those found in the two sediment cores of the Ross Sea (Figure 4).…”

Section: Discussionmentioning

confidence: 99%

“…Kang et al (2009) reported that BC accounted for 5%-26% of the TOC in East China Sea sediments. More recently, Ren et al (2019) found that BC accounted for 4%-15% of the TOC preserved in the shelf and slope sediments of the Arctic Ocean, and Zhang et al (2022) reported that BC accounted for 10% of the TOC preserved in the deep trench sediments of the North Pacific. Using chemical oxidation methods, Masiello and Druffel (1998) reported that BC made up 12%-31% of the TOC in the two sediment cores collected from the northeastern Pacific and the South Ocean.…”

Section: Sources and Deposition Of Pyc In The Sedimentmentioning

confidence: 99%

“…Therefore, PyC produced from C 3 and C 4 vegetation fires can be definitively identified in marine sediments. For example, δ 13 C values of PyC (or BC) preserved in shelf sediments from the Arctic (−20.8‰ to −24.6‰, Ren et al., 2019), the Santa Monica Basin (−24.3‰ to −24.8‰, Masiello & Druffel, 2003), and the deep trenches in the North Pacific (−22.3‰ to −27.7‰, Zhang et al., 2022) all had C 3 plant and fossil fuel signatures, suggesting that they mainly originated from the burning of C 3 plant biomass and fossil fuels. In contrast, the PyC isolated from deep‐sea sediments from the South China Sea showed strong C 4 biomass δ 13 C signatures, suggesting wildfires from the C 4 biomass expansion in East Asia during the Early Holocene and Miocene (Pang et al., 2021; Zhou et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

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Isotopic Records of Ancient Wildfires in C₄ Grasses Preserved in the Sediment of the Ross Sea, Antarctica

Ren

Luo

Zhang

et al. 2022

Geophysical Research Letters

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We report carbon isotopic values in total organic carbon (TOC) and pyrogenic carbon (PyC) preserved in two sediment cores from the Ross Sea, Antarctica. The δ13C values of PyC ranged from −10.9‰ to −17.2‰, with distinct differences from the δ13C values of TOC (−24.1‰ to −26.1‰) in the sediments. The radiocarbon ages of PyC were 9,128 and 8,410 years old on average in the two cores but were thousands of years younger than the ages of TOC at the same core depth. These isotopic records provide strong evidence indicating that the PyC was produced from ancient wildfires predominantly in C4 vegetation and transported to Antarctica in the atmosphere. We suggest that ancient wildfires in predominantly C4 grasslands likely frequently occurred on a large scale and at a high intensity in the Southern Hemisphere during the last deglaciation to mid‐Holocene period of 14,800–4,200 years ago.

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Section: Discussionmentioning

confidence: 99%

Section: Sources and Deposition Of Pyc In The Sedimentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Isotopic Records of Ancient Wildfires in C₄ Grasses Preserved in the Sediment of the Ross Sea, Antarctica

Ren

Luo

Zhang

et al. 2022

Geophysical Research Letters

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“…Use the vertical thruster to move the vehicle about 1.5 m above the sea bottom and keep the ARV in auto-depth mode. (6) Near bottom operation to finish designated tasks. The vehicle is controlled remotely by operators on the ship.…”

Section: Remotely-operated Modementioning

confidence: 99%

“…Scientific activities in hadal zones rely heavily on developing full ocean depth (FOD) vehicles, including human occupied vehicles (HOVs), unmanned submersibles, landers, etc. In the last five years, remarkable progress has been made in marine biology, geography, geochemistry, and marine environmental science related to hadal zones (e.g., [5,6]). These progress and scientific discoveries could be in large part contributed to by samples obtained by all kinds of underwater vehicles that can operate at full ocean depth.…”

Section: Introductionmentioning

confidence: 99%

A Prototype Design and Sea Trials of an 11,000 m Autonomous and Remotely-Operated Vehicle Dream Chaser

Jiang

Lü

Wang

et al. 2022

JMSE

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To better study the biology and ecology of hadal trenches for marine scientists, the Hadal Science and Technology Research Center (HAST) of Shanghai Ocean University proposed to construct a movable laboratory that includes a mothership, several full-ocean-depth (FOD) submersibles, and FOD landers to obtain samples in the hadal trenches. Among these vehicles, the project of an FOD autonomous and remotely-operated vehicle (ARV) named “Dream Chaser” was started in July 2018. The ARV could work in both remotely-operated and autonomous-operated modes, and serves large-range underwater observation, on-site sampling, surveying, mapping, etc. This paper proposed a novel three-body design of the FOD ARV. A detailed illustration of the whole system design method is provided. Numerical simulations and experimental tests for various sub-systems and disciplines have been conducted, such as resistance analysis using the computational fluid mechanics method and structural strength analysis for FOD hydrostatic pressure using the finite element method and pressure chamber tests. In addition, components tests and the entire system tests have been performed on land, underwater, and in the pressure chamber in the laboratory of HAST, and the results are discussed. Extensive experiments of two critical components, i.e., the thrusters and ballast-abandoning system, have been conducted and further analyzed in this paper. Finally, the procedures and results of lake trials, South China Sea trials and the first phase of Mariana Trench sea trials of the ARV in 2020 are also introduced. This paper provides a design method for the novel three-body FOD ARV. More importantly, the lessons learned from the FOD pressure test, lake tests, and sea trials, no matter the success or failure, will guide future endeavors and the application of ARV Dream Chaser and underwater vehicles of this kind.

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Sediment Accumulation and Carbon Burial in Four Hadal Trench Systems

Oguri

Masqué

Zabel

et al. 2022

Preprint

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Hadal trenches are considered to act as depocenters for organic material, although pathways for the material transport and deposition rates are poorly constrained. Here we assess focusing, deposition and accumulation of material and organic carbon in four hadal trench systems underlying different surface ocean productivities; the eutrophic Atacama and Kuril-Kamchatka trenches, the mesotrophic Kermadec trench and the oligotrophic Mariana Trench. The study is based on the distributions of naturally occurring 210 Pb ex , 137 Cs and total organic carbon from recovered sediment cores and by applying previously quantified benthic mineralization rates. Periods of steady deposition and discreet mass-wasting deposits were identified from the profiles and the latter were associated with historic recorded seismic events in the respective regions. During periods without mass wasting, the estimated focusing factors along trench axes were elevated, suggesting more or less continuous downslope focusing of material toward the interior of the trenches. The estimated organic carbon deposition rates during these periods exhibited extensive site-specific variability, but were generally similar to values encountered at much shallower settings such as continental slopes and margins. Organic carbon deposition rates during periods of steady deposition were not mirrored by surface ocean productivity, but appeared confounded by local bathymetry. The inclusion of deposition mediated by mass-wasting events enhanced the sediment and organic carbon accumulations for the past ∼150 years by up to a factor of ∼4. Thus, due to intensified downslope material focusing and infrequent mass-wasting events, hadal trenches are important sites for deposition and sequestration of organic carbon in the deep sea.Plain Language Summary Hadal trenches (>6,000 m water depth) occupy ∼1% of the world's ocean floor yet are largely underexplored, but recent studies have shown that these environments are depocenters for organic material and microbial activity is intensified when compared to shallower abyssal plains. However, transport and accumulation of sediment material to these hadal trenches is poorly understood. This study investigates sedimentation and accumulation dynamics of organic carbon in trenches using results of radionuclide analysis (in sediment from the Atacama, Kuril-Kamchatka, Kermadec, and Mariana trenches). The analysis shows that trench sediments consist of discreet layers representing both periods of continuous deposition and sudden mass-wasting events often triggered by historic earthquakes. Down slope focusing of material, intensified the deposition along the trench axes. However, the deposition rates exhibited extensive site-specific variations that were partly related to mass-wasting events which greatly enhanced not only mass accumulation but also organic carbon accumulation at the trench axes. Our results illustrate that mass-wasting events play an important role on supplying organic carbon to hadal communities and suggest that hadal tr...

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The hadal zone is an important and heterogeneous sink of black carbon in the ocean

Cited by 17 publications

References 66 publications

Isotopic Records of Ancient Wildfires in C₄ Grasses Preserved in the Sediment of the Ross Sea, Antarctica

Isotopic Records of Ancient Wildfires in C₄ Grasses Preserved in the Sediment of the Ross Sea, Antarctica

A Prototype Design and Sea Trials of an 11,000 m Autonomous and Remotely-Operated Vehicle Dream Chaser

Sediment Accumulation and Carbon Burial in Four Hadal Trench Systems

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The hadal zone is an important and heterogeneous sink of black carbon in the ocean

Cited by 17 publications

References 66 publications

Isotopic Records of Ancient Wildfires in C4 Grasses Preserved in the Sediment of the Ross Sea, Antarctica

Isotopic Records of Ancient Wildfires in C4 Grasses Preserved in the Sediment of the Ross Sea, Antarctica

A Prototype Design and Sea Trials of an 11,000 m Autonomous and Remotely-Operated Vehicle Dream Chaser

Sediment Accumulation and Carbon Burial in Four Hadal Trench Systems

Contact Info

Product

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Isotopic Records of Ancient Wildfires in C₄ Grasses Preserved in the Sediment of the Ross Sea, Antarctica

Isotopic Records of Ancient Wildfires in C₄ Grasses Preserved in the Sediment of the Ross Sea, Antarctica