Purification of Disc-Shaped Diatoms from the Southern Ocean Sediment by a Cell Sorter to Obtain an Accurate Oxygen Isotope Record
Purification of Disc-Shaped Diatoms from the Southern Ocean Sediment by a Cell Sorter to Obtain an Accurate Oxygen Isotope Record
复制标题
通过细胞分选仪纯化南大洋沉积物中的盘状硅藻以获得准确的氧同位素记录
DOI：
10.1021/acsearthspacechem.1c00201
复制
发表时间：
2021
影响因子：
3.4
通讯作者：
Ikehara Minoru
中科院分区：
文献类型：
--
作者：
Ijiri Akira;Izumi Takeshi;Morono Yuki;Kato Yuji;Terada Takeshi;Ikehara Minoru
硅藻体的氧同位素组成（δ18O）可能是一个定量的古环境指标。然而，由于硅藻体的小尺寸，δ18O分析存在一定的不确定性，难以去除粘土矿物污染和分类群特异性分离。黏土矿物污染严重影响了δ18O的测量，块状硅藻的δ18O包含了不同季节和不同水深硅藻的混合信息。为了解决这一问题，我们建立了一种利用细胞分选器纯化圆盘状硅藻囊体的新方法，成功地去除了粘土矿物污染，并限制了用于δ18O分析的物种数量。我们利用从南大洋印度洋康拉德隆起提取的沉积物岩心样本开发了这种方法。首先，通过筛分、洗脱和重液分离对圆盘状硅藻进行富集和清洗。然后用细胞分选器进一步纯化样品。无论硅藻组合或岩心样品中的沉积物类型如何，该方法生成的样品由超过95%的圆盘状硅藻组成，以thalassiosira lentiginosa(Janisch) Fryxell硅藻为主，这种硅藻在南大洋普遍存在。纯化圆盘状硅藻沉积岩心的δ18O剖面显示了约40 ka以来的末次冰期旋回，可与LR04底栖生物δ18O叠记录和EPICA Dome C冰芯的温度记录相对应，表明该方法有助于获得与冰期-间冰期旋回相关的硅藻δ18O准确记录。
The oxygen isotopic composition (δ18O) of diatom frustules is potentially a quantitative paleoenvironmental proxy. However, δ18O analysis has some uncertainties because of difficulties in removing clay-mineral contamination and taxon-specific separation due to the small size of diatom frustules. The clay-mineral contamination seriously affects δ18O measurements, and the δ18O of bulk diatoms contains a mixture of information from diatoms living in various seasons and water depths. To resolve such problems, we established a new method for purifying the frustules of disc-shaped diatoms using a cell sorter and succeeded in removing the clay-mineral contamination and restricting the number of species for the δ18O analysis. We developed this method using samples from a sediment core retrieved from the Conrad Rise in the Indian Ocean sector of the Southern Ocean. First, the disc-shaped diatoms were enriched and cleaned by sieving, elutriation, and heavy-liquid separation. The samples were then further purified by a cell sorter. Regardless of the diatom assemblage or the sediment type in the core sample, this method generated samples consisting of more than 95% disc-shaped diatoms, dominated byThalassiosira lentiginosa(Janisch) Fryxell, which occurs ubiquitously throughout the Southern Ocean. The δ18O profile for the sediment core obtained from purified disc-shaped diatoms showed the last glacial cycle since ca. 40 ka, which can be correlated with the LR04 benthic δ18O stack record and the temperature record in the EPICA Dome C ice core, indicating that this method can contribute to obtaining an accurate δ18O record of diatoms associated with glacial–interglacial cycles.