Contribution of terrestrially derived phytolith as a marine silicon sink

2021 ◽  
Author(s):  
Vidusanka Thilakanayaka ◽  
Luo Chuanxiu* ◽  
Rong Xiang
Keyword(s):  
Marine Environment ◽  
Marine Sediment ◽  
Biogenic Silica ◽  
Carbon Sink ◽  
Total Weight ◽  
Sediment Layer ◽  
Size Classes ◽  
The Core ◽  
Silicon Cycle ◽  
Oceanic Sediment

<p>Silicon is important as a nutrient for phytoplankton (diatom, radiolarian, silicoflagellates and sponges) and for the phytolith production by terrestrial vegetation. Silicon also contributes in removing carbon dioxide from the atmosphere through silicate weathering.  Hence it is important to understand the behavior of the silicon cycle throughout earth history. Silica is the second most abundant element in the earth's crust and the concentration of silicic acid in the marine environment has not changed since the past 10,000 years. Phytolith plays an important role in the silicon cycle. While the phytoplankton in marine environment bioengineers silica within the water column, phytolith transports terrestrial biogenic silica into the marine environment and act as a silicon sink. Though astonishingly, very few researches have been carried out in the field of marine phytolith sink and also on the phytoliths in the marine environment.</p><p>For this study, we have chosen the world highest terrestrial sediment receiving submarine fan, the Bengal fan. The core sample was extracted at a water depth of 3520m at 85.960985 N, 9.99351 E. 24 phytolith types were identified and all the morphotypes were counted dividing into three size classes. These size classes were specific to considering morphotypes. Most related simple geometries were used to calculate the volume of phytolith cells and these volume data were used in calculating the total volume of phytolith in one gram of sediment by combining with an absolute abundance of phytolith data for each size class, which were later used to calculate the total weight of phytolith in one gram of marine sediment. According to the results in deep oceanic sediment at the core, the location contains ⁓0.15mg/g phytolith during the low phytolith flux periods (ex. Late Holocene) and ⁓2.678mg/g of phytolith during the high phytolith flux periods such as 25ka to 30ka B.P. and around the beginning of deglaciation. After removing 10% from the total weight as phytolith occluded carbon (PhytOC), phytolith derived biogenic silica content in sediment varies from ⁓0.135mg/g - ⁓2.41mg/g. Thus, phytolith in marine sediment contributes as a permanent silicon and carbon sink. By considering average marine sediment density as 1.7g/cm<sup>3</sup>, in a 1cm thick, one square km sediment layer contains ⁓2 to 40 metric tons of biogenic silica derived from phytolith, during low and high phytolith flux periods. This study serves as the pioneer of this field of study and further it is important to investigate the release of biogenic silica in to marine environment by phytolith and PhytOC content in different morphotypes and in different geological regions, for better understanding the contribution of phytolith to the biogenic silicon cycle in the marine environment.</p><p>Keywords: Marine phytolith, Deep oceanic sediment, Silicon cycle, Phytolith Flux, Silicon sink.</p><p><strong>Acknowledgements</strong></p><p>This work was funded by the National Natural Science Foundation of China (NSFC 41876062) and Key Special Project for Introduced Talents Team of Southern Marine Science and EngineeringGuangdong Laboratory (Guangzhou) (GML2019ZD0206).</p><p> </p>

Preliminary Research of Manufacturing Technology for ITER Magnet Supports

2012 ◽  
Vol 249-250 ◽  
pp. 466-471
Author(s):  
Bing Lin Hou ◽  
Peng Yuan Li ◽  
Shu Juan Yang ◽  
Chuan Jie Pan
Keyword(s):  
Reliable Method ◽  
Manufacturing Technology ◽  
Total Weight ◽  
Toroidal Field ◽  
Poloidal Field ◽  
Full Size ◽  
Safety Requirements ◽  
The Core ◽  
Preliminary Research ◽  
Working Procedure

The International Thermal Experiment Reactor (ITER) is designed to operate for 20 years with high safety requirements. The magnets with their total weight being about 10,000t sit at the core of the ITER machine. In order to guarantee the safety of the ITER machine, the research of the manufacturing technology for ITER magnet supports (MS) is an indispensable working procedure before the MS are produced. The MS consist of toroidal field (TF) gravity supports (GS), poloidal field (PF) supports and correction coils (CC) supports. This paper summarizes that the preliminary research results for the manufacturing of the GS with thermal anchor, the reliable method to manufacture the U-shaped clamp with tapered slots for PF coil supports and the special devices for test of full-size fasteners used in all the MS.

A proposed source model for the great Kau, Hawaii, earthquake of 1868

1988 ◽  
Vol 78 (4) ◽  
pp. 1450-1462
Author(s):  
Max Wyss
Keyword(s):  
The United States ◽  
Source Model ◽  
Recurrence Time ◽  
Sediment Layer ◽  
Ground Shaking ◽  
Mauna Loa ◽  
Rupture Plane ◽  
Felt Area ◽  
Eastern Edge ◽  
Oceanic Sediment

Abstract On 2 April 1868, an earthquake occurred which destroyed all stone buildings in southern Hawaii. It was felt on Kauai Island at 600 km, and ground shaking of intensity VII was reported up to 130 km distance. Based on the magnitude versus felt-area relationship for Hawaii, it is estimated that the magnitude of the earthquake was about 8. The foreshock sequence lasted 5 days, and the aftershocks lasted for years to perhaps a decade. It appears that this earthquake was one of the very few largest events in historic time in the United States, excluding Alaska, but its return period is unknown. It is proposed that the source of this earthquake was slip of the upper crust towards the southeast along a near-horizontal plane at approximately 9 km depth. The rupture plane may have had dimensions of at least 50 km × 80 km. It is proposed that its eastern edge extended from near Mauna Loa's summit to the south along the volcano's southwest rift. In this model, magma intrusions into Mauna Loa and its southwest rift provide the stresses which act perpendicular to the rift and which push the volcano's southwest flank away from the edifice of the island of Hawaii. The oceanic sediment layer upon which this edifice is deposited acts as a layer of weakness containing the fault plane. This model explains the eruptive pattern of Mauna Loa and its southwest rift, as well as the growing separation between the southwest rift zones of the two volcanoes: Kilauea and Mauna Loa. Geodetic monitoring of southern Hawaii, particularly of the area between the two active volcano's southwest rifts, could test this hypothesis and lead to an estimate of the recurrence time.

Part V Subject Matter, Ch.31 The Protection of the Marine Environment Pollution and Fisheries

2021 ◽  
Author(s):  
Fabra Adriana
Keyword(s):  
Marine Environment ◽  
Biological Diversity ◽  
Marine Pollution ◽  
Case Law ◽  
Habitat Destruction ◽  
Marine Biodiversity ◽  
Technological Changes ◽  
The Core ◽  
Sources Of Pollution

This chapter begins by looking at the role of the 1982 UN Law of the Sea Convention (UNCLOS) as the framework legal instrument on the oceans. Indeed, the UNCLOS is one of the most significant international law instruments of all time and is at the core of today's governance of the oceans. UNCLOS is a product of the time when it was negotiated, which brought together a desire to provide global stability to competing jurisdictional claims over the oceans and devise solutions to rapidly increasing rates of marine pollution. However, technological changes and increased or unforeseen sources of pollution and habitat destruction have exposed some of the Convention's limitations, which derive from a fragmented perspective of the marine environment, and a failure to address the interaction between different ocean uses and marine stressors and provide rules on the conservation of marine biological diversity. The chapter then evaluates global and regional treaty requirements, soft law instruments, and case law concerning the protection of the marine environment from various sources of pollution, and the conservation of marine living resources, with a focus on fisheries, and the protection of marine biodiversity.

Design of Monitoring System Used in Sink-Float Safety Device for Marine Engineering Equipment

2013 ◽  
Vol 475-476 ◽  
pp. 635-638
Author(s):  
Zi Yue Wu ◽  
Jie Qi ◽  
Chen Nan Xue
Keyword(s):  
Data Management ◽  
Monitoring System ◽  
Marine Environment ◽  
Experimental Results ◽  
Software Architectures ◽  
Safety Device ◽  
Engineering Equipment ◽  
The Core ◽  
Marine Engineering

A monitoring system used in marine sink-float safety device is introduced. The ARM Cortex-M3 is the core of microcontroller in this system, and the hardware and software architectures of the monitoring system are designed. The designed monitoring system can multi-point monitor marine environment around sink-float safety device, by doing this, the safety device can take marine equipment to escape from harsh marine environment by submerging a certain depth. So we can make sure marine equipment safe and normal. The experimental results show that the sink-float safety device can work normally in the harsh marine environment with the monitoring system. The acquisition of multi-point environment monitor as well as data management is achieved effectively. The reliability and safety of equipment are guaranteed by the sink-float safety device.

scholarly journals Anomalous flow below 2700 m in the EPICA Dome C ice core detected using δ<sup>18</sup>O of atmospheric oxygen measurements

2007 ◽  
Vol 3 (1) ◽  
pp. 63-93 ◽  
Author(s):  
G. B. Dreyfus ◽  
F. Parrenin ◽  
B. Lemieux-Dudon ◽  
G. Durand ◽  
V. Masson-Delmotte ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Northern Hemisphere ◽  
Marine Sediment ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
The Core ◽  
Sediment Records ◽  
Ice Core Record ◽  
Orbital Precession ◽  
Oxygen Measurements

Abstract. While there are no indications of mixing back to 800 000 years in the EPICA Dome C ice core record, comparison with marine sediment records shows significant differences in the timing and duration of events prior to stage 11 (~430 ka, thousand of years before 1950). A relationship between the isotopic composition of atmospheric oxygen (δ18O of O2, noted δ18Oatm) and daily northern hemisphere summer insolation has been observed for the youngest four climate cycles. Here we use this relationship with new δ18O of O2 measurements to show that anomalous flow in the bottom 500 m of the core distorts the duration of events by up to a factor of 2. By tuning δ18Oatm to orbital precession we derive a corrected thinning function and present a revised age scale for the interval corresponding to Marine Isotope Stages 11–20 in the EPICA Dome C ice core. Uncertainty in the phasing of δ18Oatm with respect to insolation variations in the precession band limits the accuracy of this new agescale to ±6 kyr (thousand of years). The previously reported ~30 kyr duration of interglacial stage 11 is unchanged. In contrast, the duration of stage 15.1 is reduced by a factor of 2, from 31 to 16 kyr.

scholarly journals Accounting for the Missing Silica in the Marine Sediment Cycle

Eos ◽  
2018 ◽  
Vol 99 ◽  
Author(s):  
Terri Cook
Keyword(s):  
Marine Sediment ◽  
Biogenic Silica ◽  
Continental Margins ◽  
Silicon Based

Cosmogenic silicon-based estimates of the amount of biogenic silica stored in clays along continental margins could explain the large discrepancy in the nutrient’s global marine budget.

scholarly journals The role of water in Earth's mantle

2019 ◽  
Vol 7 (1) ◽  
pp. 224-232 ◽  
Author(s):  
Eiji Ohtani
Keyword(s):  
Solid Solution ◽  
Transition Zone ◽  
Lower Mantle ◽  
Water Solubility ◽  
High Pressures ◽  
Low Velocity ◽  
The Core ◽  
Velocity Anomalies ◽  
Oceanic Sediment

Abstract Geophysical observations suggest that the transition zone is wet locally. Continental and oceanic sediment components together with the basaltic and peridotitic components might be transported and accumulated in the transition zone. Low-velocity anomalies at the upper mantle–transition zone boundary might be caused by the existence of dense hydrous magmas. Water can be carried farther into the lower mantle by the slabs. The anomalous Q and shear wave regions locating at the uppermost part of the lower mantle could be caused by the existence of fluid or wet magmas in this region because of the water-solubility contrast between the minerals in the transition zone and those in the lower mantle. δ-H solid solution AlO2H–MgSiO4H2 carries water into the lower mantle. Hydrogen-bond symmetrization exists in high-pressure hydrous phases and thus they are stable at the high pressures of the lower mantle. Thus, the δ-H solid solution in subducting slabs carries water farther into the bottom of the lower mantle. Pyrite FeO2Hx is formed due to a reaction between the core and hydrated slabs. This phase could be a candidate for the anomalous regions at the core–mantle boundary.

scholarly journals Pliocene expansion of C<sub>4</sub> vegetation in the Core Monsoon Zone on the Indian Peninsula

2020 ◽  
Vol 16 (6) ◽  
pp. 2533-2546
Author(s):  
Ann G. Dunlea ◽  
Liviu Giosan ◽  
Yongsong Huang
Keyword(s):  
Fatty Acids ◽  
Marine Sediment ◽  
Late Miocene ◽  
Local Conditions ◽  
Indian Peninsula ◽  
The Core ◽  
Leaf Wax ◽  
Highly Sensitive ◽  
The Indian Ocean ◽  
International Ocean Discovery Program

Abstract. The expansion of C4 vegetation during the Neogene was one of the largest reorganizations of Earth's terrestrial biome. Once thought to be globally synchronous in the late Miocene, site-specific studies have revealed differences in the timing of the expansion and suggest that local conditions play a substantial role. Here, we examine the expansion of C4 vegetation on the Indian Peninsula since the late Miocene by constructing a ∼6-million-year paleorecord with marine sediment from the Bay of Bengal at Site U1445, drilled during International Ocean Discovery Program Expedition 353. Analyses of element concentrations indicate that the marine sediment originates from the Mahanadi River in the Core Monsoon Zone (CMZ) of the Indian Peninsula. Hydrogen isotopes of the fatty acids of leaf waxes reveal an overall decrease in the CMZ precipitation since the late Miocene. Carbon isotopes of the leaf wax fatty acids suggest C4 vegetation on the Indian Peninsula existed before the end of the Miocene but expanded to even higher abundances during the mid-Pliocene to mid-Pleistocene (∼3.5 to 1.5 million years ago). Similar to the CMZ on the Indian Peninsula, a Pliocene expansion or re-expansion has previously been observed in northwest Australia and in East Africa, suggesting that these tropical ecosystems surrounding the Indian Ocean remained highly sensitive to changes in hydroclimate after the initial spread of C4 plants in late Miocene.

scholarly journals Screening of Antibacterial Metabolites from Marine Soil, Kodiyampaiayam, Tamilnadu

2019 ◽  
Vol 8 (3S3) ◽  
pp. 571-575
Keyword(s):  
Antibacterial Activity ◽  
Secondary Metabolites ◽  
Drug Development ◽  
Marine Environment ◽  
Marine Sediment ◽  
Crude Extract ◽  
Pathogenic Bacteria ◽  
Soil Samples ◽  
Morphology Characteristic ◽  
New Antibiotics

The marine environment is a rich resource for isolating exploited microorganisms. In recent years, antibiotics have become important in this study of new antibiotics that show antiviral, anticoagulant and cardiac properties. Soil samples were collected from different area and isolated the bacterial colonies were separately streaking in agar plates (KP1, KP3, KP6, KP7 and KP9). The bacteria were done by morphology characteristic after that bacterial crude extract was taken separately. The crude extract was used in antibacterial activity against human pathogenic bacteria. There KP 7 and KP 9 havethe highest activity in B. subtilis and S. pyogenes rest of the samples also had activity comparing to these samples (KP 7 and KP 9) is highest zone inhibition developing. The marine sediment having so many microbes and secondary metabolites, therefore,the most useful drug development..

scholarly journals Silicon cycle in the Tropical South Pacific: evidence for an active pico-sized siliceous plankton

2018 ◽  
Author(s):  
Karine Leblanc ◽  
Véronique Cornet ◽  
Peggy Rimmelin-Maury ◽  
Olivier Grosso ◽  
Sandra Hélias-Nunige ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Biogenic Silica ◽  
New Caledonia ◽  
South Pacific ◽  
Tropical Pacific ◽  
Biogeochemical Cycle ◽  
Silicon Cycle ◽  
Standing Stocks ◽  
Negligible Contribution

Abstract. This article presents data regarding the Si biogeochemical cycle during two oceanographic cruises conducted in the Southern Tropical Pacific (BIOSOPE and OUTPACE cruises) in 2005 and 2015. It involves the first Si stock measurements in this understudied region, encompassing various oceanic systems from New Caledonia to the Chilean upwelling between 8 and 34° S. Some of the lowest levels of biogenic silica standing stocks ever measured were found in this area, notably in the Southern Pacific Gyre, where Chlorophyll a concentrations are most depleted worldwide. Integrated biogenic silica stocks are as low as 1.08 ± 0.95 mmol m−2, and are the lowest stocks measured in the Southern Pacific. Size-fractionated biogenic silica concentrations revealed a non-negligible contribution of the pico-sized fraction (

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