Coccolithophore abundance, biomass and particulate inorganic carbon concentration in the South China Sea in June/July 2018

We investigated coccolithophore abundance, coccolith calcite biomass, and particulate inorganic carbon (PIC) concentration in the deep chlorophyll maximums in the South China Sea. The field investigation was conducted on board the research vessel “TAN KAH KEE (JiaGeng)” during cruise NORC2018-05 from June to July, 2018. 2L of water samples were collected with a conductivity-temperature-depth (CTD) rosette sampler and filtered on 0.8 μm pore-size polycarbonate membranes. Coccolithophores were checked using a light microscope. Coccolith calcite biomass was calculated based on coccolithophore abundance and average coccolith mass. 3L of water samples for PIC were also collected and filtered on 0.8 μm pore-size polycarbonate membranes. PIC was determined by measuring the [Ca2+] concentration in seawater using inductively coupled plasma–mass spectrometry

Stable isotope record of Gephyrocapsa coccoliths of sediment core KX21-2

Coccolithophores play important roles in marine biochemistry due to the processes of calcification and photosynthesis. Coccoliths are produced intracellularly, and cells produce coccoliths with stable isotopes distinct from theoretically precipitated inorganic calcite due to the influences of coccolithophore physiology, which are the so-called vital effects. The coccolith isotopic vital effects show large variations between species and hamper the use of coccolith isotopes in paleoceanography. In addition, learning the coccolith isotopic vital effects can help to better understand the carbon fractionation in coccolithophore cell, so as to provide a new insight in reconstructing sea water carbonate system (e.g., from alkenone C or directly from coccolith C) in geological past. In the present study, we investigated the morphological parameters, growth rate, and coccolith stable isotope compositions of Gephyrocapsa, the most universal alkenone-producing coccolithophore across the Pleistocene. These data allow us to estimate the influences of Gephyrocapsa morphology as well as the growth rate on coccolith vital effects. The results showed that Gephyrocapsa morphology, as well as coccolith isotopes, varied with species and morphotype changes, which were evolutionarily forced over the past 400 ka. The small Gephyrocapsa morphotypes (G. caribbeanica and Gephyrocapsa <3 μm) produced more robust coccoliths with relatively heavier isotopes for both carbon and oxygen than that of the larger-sized G. oceanica. The carbon and oxygen vital effects were significantly correlated and showed negative values, suggesting a kinetic effect on bicarbonate formation during calcification. The Gephyrocapsa growth rate showed a glacial–interglacial cyclicality, and had close relations with coccolith isotopic vital effects before MIS 8 when G. oceanica dominated. It is suggested that coccolith isotopic fractionation were influenced by coccolithophore growth rate, however these effects were superimposed on an evolutionary forced coccolithophore (coccolith) size changes

Total morphosynthesis of biomimetic prismatic-type CaCO3 thin films

The exterior layers of mollusk shells are prismatic in nature, endowing them with stiffness and wear resistance. Inspired by these biominerals, here, Jiang and colleagues grow structurally similar prismatic-type CaCO3 thin films with comparable stiffness and hardness

Total morphosynthesis of biomimetic prismatic-type CaCO3 thin films

我校材料学院姜源副教授，与浙江大学唐睿康教授课题组、德国Konstanz大学Helmut Cölfen教授课题组合作，首次利用全合成手段获得了仿贝类棱柱层结构的碳酸钙薄膜，并实现了仿生薄膜微结构的精准调控，由此获得了优异的力学性能。本研究团队基于生物矿物的空间结构异质性，并参考了传统晶态薄膜材料合成中的液相外延方法，首次设计出了多步仿生矿化路线，在常温液相条件下成功地构筑了利用聚电解质稳定的矿物种子层，并在此基础上利用外延矿化方法构筑了碳酸钙的棱柱层结构。本研究制备的棱柱层薄膜不但与相对应的生物矿物在微结构上具有高度的相似性，同时还具有类似的硬度和杨氏模量。文中提出的基于种子层外延生长的多步矿化路线是获得棱柱层仿生结构的普适方法，也加深了人们对于生物矿化机制的认识。【Abstract】Biomimetic mineralization can lead to advanced crystalline composites with common chemicals under ambient conditions. An exceptional example is biomimetic nacre with its superior fracture toughness. The synthesis of the prismatic layer with stiffness and wear resistance nonetheless remains an elusive goal. Herein, we apply a biomimetic mineralization method to grow prismatic-type CaCO3 thin films, mimicking their biogenic counterparts found in mollusk shells with a three-step pathway: coating a polymer substrate, deposition of a granular transition layer, and mineralization of a prismatic overlayer. The synthetic prismatic overlayers exhibit structural similarity and comparable hardness and Young’s modulus to their biogenic counterparts. Furthermore, employment of a biomacromolecular soluble additive, silk fibroin, in fabrication of the prismatic thin films leads to micro-/nano-textures with enhanced toughness and emerging under-water superoleophobicity. This study highlights the crucial role of the granular transition layer in promoting competition growth of the prismatic layer.Y.J. acknowledges financial support from the National Natural Science Foundation of China (NSFC; 21303144) and Science Foundation of the Fujian Province, China (2014J01207). R.T. acknowledges financial support from NSFC (21625105). X.Y.L. thanks NSFC (U1405226), the “111” Project (B16029), Fujian Provincial Bureau of Science & Technology (2014H6022), and the 1000 Talents Program from Xiamen University

Major Pleistocene stages in a carbon perspective: The South China Sea record and its global comparison

Carbon isotope sequences at Ocean Drilling Program Site 1143, South China Sea, reveal a long-term cyclicity of similar to500 kyr that is superimposed on the glacial cycles and is present in long delta(13)C sequences from all oceans. The Quaternary delta(13)C record is punctuated by four delta(13)C maximum events: delta(13)Cmax-I, which began in marine isotope stage (MIS) 3 around 50-60 kyr ago, delta(13)Cmax-II (MIS 13, 0.47-0.53 Ma), delta(13)Cmax-III (MIS 27-29, 0.97-1.04 Ma) and delta(13)Cmax-VI (MIS 53-57, 1.55-1.65 Ma). As the same cyclicity is also found in carbonate curves, the delta(13)Cmax events must denote major reorganization in the carbon reservoir of the global ocean. They also are associated with major changes in glacial cyclicity, such as the Mid-Brunhes Event following delta(13)Cmax-II and the Mid-Pleistocene Revolution following delta(13)Cmax-III, which in turn were associated with expansion of the ice sheets. From a carbon perspective, therefore, the Quaternary period has passed through three major stages, and each appears to represent a further step in ice cap development