Diatoms, Grain Size, Magnetic Susceptibility, and Cesium and Lead Isotopes from Short HAPS Cores Collected on the Bering Sea Shelf

Regime shift in the Pacific Decadal Oscillation (PDO) and changes in the intensity of the Aleutian Low have manifest significant impacts on the Bering Sea ecosystem from commercially important fisheries to phytoplankton. This leads us to examine Bering Sea shelf sediments in an effort to determine if recent environmental changes are recorded in the sediments deposited over the past half a century. Samples were collected on board the USCGC Healy Icebreaker during May 2006 and June 2007. Haps cores were collected and subsampled either by slicing the sediments at 1 cm intervals or by pushing a polyvinyl chloride (PVC) pipe into the center of the Haps core. The data set archived here contains diatom counts, detailed grain size analysis, magnetic susceptibility, and x-radiographs for a suite of short cores. One core, DBSB, was dated using 210-Pb and 137-Cs. It was found to reach back to 1949 at 13 cm depth. Forty-six diatom taxa are recorded and diatom counts are presented either as raw counts or as relative percent abundances. Grain size is calculated using a laser diffraction particle size analyzer and is reported as weight percent for grain size bins ranging from 0.01 to 3700 μm. Lead and cesium isotopes are reported in Becquerels per gram and magnetic susceptibility is reported in SI units. X-radiographs are archived as images. These data show that the sediments are moderately bioturbated, but still reflect changing environmental conditions since 1950.

太平洋年代际振荡（Pacific Decadal Oscillation, PDO）的位相转换与阿留申低压（Aleutian Low）强度变化，对白令海（Bering Sea）生态系统具有显著影响，其影响范畴覆盖商业性渔业至浮游植物群落。基于此，本研究对白令海陆架沉积物展开调查，旨在探明近半个世纪以来的沉积记录是否留存了近期环境变化的信息。研究样品于2006年5月与2007年6月，搭载美国海岸警卫队“希利”号破冰船（USCGC Healy Icebreaker）完成采集。本次研究获取了Haps岩心，并通过两种方式进行分样：一是以1厘米为间隔对沉积物进行切片，二是将聚氯乙烯（PVC）管推入Haps岩心中心以获取样品。本数据集归档内容包含一套短岩心的硅藻（diatom）计数、高精度粒度分析（grain size analysis）、磁化率（magnetic susceptibility）数据及X射线影像（x-radiographs）。其中编号为DBSB的岩心采用铅-210（210-Pb）与铯-137（137-Cs）进行定年，结果显示其在13厘米深度处的沉积年代可追溯至1949年。本次研究共记录46个硅藻类群，硅藻计数结果以原始计数或相对百分丰度的形式呈现。粒度分析采用激光衍射粒度分析仪完成，以0.01至3700微米的粒级区间为单位，以重量百分比形式报告各粒度粒级的占比。铅与铯同位素数据以贝可勒尔每克为单位记录，磁化率数据采用国际单位制（SI units）报告。X射线影像以图像格式归档。数据分析表明，研究区沉积物存在中等程度的生物扰动（bioturbated），但仍可反映1950年以来的环境演变过程。