Dissolved silicon isotopic compositions in the <scp>E</scp>ast <scp>C</scp>hina <scp>S</scp>ea: Water mass mixing vs. biological fractionation

Cao, Zhimian; Dai, Minhan

doi:10.1002/lno.10124

Cited by 15 publications

(21 citation statements)

References 69 publications

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“…Likewise, the influence of resuspended sediments may be limited. In summer, the δ 30 Si value of East China Sea bottom water (+1.6‰) is lighter than in winter (+2.5‰) (Cao et al ; Zhang et al ). Processes that might generate the light summertime signal include dissolution of BSi or terrestrial lithogenic silica; the isotopic signal associated with resuspended sediments is heavier (as seen in winter).…”

Section: Discussionmentioning

confidence: 99%

Diatom bloom‐derived bottom water hypoxia off the Changjiang estuary, with and without typhoon influence

Wang

Chen

Jin

et al. 2017

Limnology & Oceanography

117

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During the summers of 2009 and 2013, seawater pH and concentrations of dissolved oxygen, inorganic carbon, and nutrients were measured off the Changjiang estuary in the East China Sea. The 2009 cruise captured the effects of Typhoon Morakot; the 2013 cruise sampled more typical conditions (no typhoon). Data from both years indicate a close correlation between high primary productivity in surface waters and hypoxia in bottom waters. Based on these observations, we developed a conceptual model to guide an exploration of processes contributing to the formation of summertime bottom hypoxia. A mixing-model analysis of the 2009 data identified a surface diatom bloom as the major (70-80%) source of the organic carbon that decomposed and ultimately led to bottom water hypoxia. Within the Changjiang River plume, depth-integrated net biological production in the water column was 1.8 g C m 22 d 21 , indicating strong autotrophic production, which in turn led to a high respiration rate of 1.2 g C m 22 d 21 in the bottom water. During both cruises, strong surface-to-bottom physical and metabolic coupling was evident. In 2009, storm-driven inputs of nutrients from elevated river discharge and strong vertical mixing helped to fuel the rapid development of a surface diatom bloom. Afterwards, stratified conditions re-established, newly formed labile organic matter sank, and bottom water oxygen was quickly consumed to an extent that hypoxia and acidification developed. To our knowledge, the observed rate of hypoxia and acidification development (within 6 d) is the fastest yet reported for the Changjiang River plume.Oxygen-minimum zones in open-ocean waters and hypoxic zones in coastal waters have received increased attention in recent research related to changing biogeochemical and climate conditions. Oceanic oxygen-minimum zones occur naturally and permanently at depths of 200-1000 m in the open ocean (Wyrtki 1962). In contrast, coastal hypoxia (dissolved oxygen [DO] <63 lmol L 21 ) appears seasonally and is believed to be largely associated with anthropogenic eutrophication. Where nutrient inputs to coastal waters result in excess primary production, depletion of oxygen in bottom waters may follow (Diaz and Rosenberg 2008; Bianchi et al.

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Section: Discussionmentioning

confidence: 99%

Diatom bloom‐derived bottom water hypoxia off the Changjiang estuary, with and without typhoon influence

Wang

Chen

Jin

et al. 2017

Limnology & Oceanography

117

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“…The exchange time for deep waters is less than 100 years, so the basin is in continuous communication with the Pacific Ocean. Thus dissolved silica concentrations and silicon isotope data in the SCS and ECS (Cao et al, , ; Okubo et al, ) derive from the central North Pacific (Beucher et al, ; Holzer & Brzezinski, ; Reynolds et al, ). Both the NPDW and NPIW are at the “end” of today's ocean conveyor and thus the oldest water in today's ocean and in the glacial ocean (Sarnthein et al, ; Sikes et al, ) with the highest nutrients, highest TCO 2 , and lowest O 2 .…”

Section: Discussionmentioning

confidence: 99%

Whole‐Ocean Changes in Silica and Ge/Si Ratios During the Last Deglacial Deduced From Long‐Lived Giant Glass Sponges

Jochum

Schuessler

Wang

et al. 2017

Geophysical Research Letters

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Silicon is a keystone nutrient in the ocean for understanding climate change because of the importance of Southern Ocean diatoms in taking up CO2 from the surface ocean‐atmosphere system and sequestering carbon into the deep sea. Here we report on silicon isotopes and germanium‐to‐silicon ratios in giant glass spicules of deep‐sea sponge Monorhaphis chuni over the past 17,000 years. In situ measurements of Si isotopes and Ge concentrations show systematic variations from rim to center of the cross sections. When calibrated against seawater concentrations using data from modern spicule rims, sponge data indicate that dissolved silica concentrations in the deep Pacific were ~12% higher during the early deglacial. These deep Pacific Ocean data help to fill an important global gap in paleo‐nutrient records. Either continental sources supplied more silica to the deglacial ocean and/or biogenic silica burial was lower, both of which may have affected atmospheric CO2.

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“…Considering the wealth of previous studies investigating the variations of Si isotopes in seawater (Reynolds et al, 2006;Grasse et al, 2013;de Souza et al, 2014;Cao et al, 2015), the study of Ge isotope systematics in seawater has strong potential both in terms of assessing the global budget of Ge in seawater and also as an oceanographic proxy that could be used in conjunction with Si isotopes to better understand changes in silicon cycling.…”

Section: Introductionmentioning

confidence: 99%

The isotope composition of inorganic germanium in seawater and deep sea sponges

Guillermic

Lalonde

Hendry

et al. 2017

Geochimica et Cosmochimica Acta

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Dissolved silicon isotopic compositions in the East China Sea: Water mass mixing vs. biological fractionation

Abstract: We present the first set of dissolved silicon isotope data in seawater (d 30

Cited by 15 publications

References 69 publications

Diatom bloom‐derived bottom water hypoxia off the Changjiang estuary, with and without typhoon influence

Diatom bloom‐derived bottom water hypoxia off the Changjiang estuary, with and without typhoon influence

Whole‐Ocean Changes in Silica and Ge/Si Ratios During the Last Deglacial Deduced From Long‐Lived Giant Glass Sponges

The isotope composition of inorganic germanium in seawater and deep sea sponges

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