Inorganic geochemistry of Pliocene-Pleistocene sediments from the Bering Sea (IODP Expedition 323) - Studying feedbacks of productivity, nutrient availability, and redox conditions in the northernmost Pacific

2009年，综合海洋钻探计划(IODP)的第323次远征在白令海发现了第一个可追溯到500万年前的连续沉积岩芯。这种独特的IODP岩芯材料具有相当大的潜力来揭示白令海的环境和气候历史。白令海是一个大型但开发不足的天然实验室，用于研究在冰川-间冰期时间尺度上的高生产力半限制上升流系统中与气候有关的生物地球化学元素循环的发展。此外，白令海具有全球相关性：(A)由于其潜在的大气二氧化碳封存和作为有机物长期埋藏在海底的潜力；(B)由于低氧、高营养的冰川水输出到北太平洋，以及对世界上最大的S海盆的生产力、层化和碳埋藏的相关影响。我们的主要目标是破译生物地球化学动力学和耦合，这些动力学和耦合到目前为止在白令海和全球都很少被研究，但对于大气-海洋二氧化碳交换，从而对于冰川-间冰期时间尺度上的气候动力学来说可能是重要的：初级生产力、中深层氧化还原条件之间的反馈，以及沉积物中的养分循环。我们将重点研究代表白令海环境制度的两个地点的沉积物，即开阔海域的U1341地点和陆坡的U1343地点。我们将构建无机地球化学沉积物记录(Ba，Fe，P，氧化还原敏感的痕量金属)，以追踪过去200-500万年来营养物质、生产力和海洋氧化还原的变化，但也将量化影响原始环境信号的成岩过程。为了评估上新世-更新世生物地球化学动力学和相互作用在更全球范围内的影响，我们将把我们在白令海的记录与北太平洋公布的数据和解释进行比较(例如，ODP145段)。综上所述，我们的主要研究课题有：1.生物生产力的发展及相关的碳掩埋。可变氧化还原条件下铁、磷的动力学及耦合。早期成岩作用对原生地球化学沉积信号的影响。白令海与北太平洋上新世-更新世地球化学条件的关系

In 2009, Expedition 323 of the Integrated Ocean Drilling Program (IODP) recovered the first continuous sediment cores from the Bering Sea extending back 5 Million years. The unique IODP core material has considerable potential to unlock the environmental and climatic history of the Bering Sea. The Bering Sea is a large, yet poorly explored natural laboratory to study the development of climate-relevant biogeochemical element cycles in a high-productivity semi-restricted upwelling system on glacial-interglacial time scales. Moreover, the Bering Sea is of global relevance (a) due to its potential for atmospheric CO2 sequentation and its burial in the sea floor as organic matter over long time scales, and (b) due to the export of low-oxygen high-nutrient glacial water to the North Pacific and related effects on productivity, stratification, and carbon burial in the world´s largest ocean basin. Our main goal is to decipher biogeochemical dynamics and coupling that have hardly been studied both in the Bering Sea and globally so far, but may be of importance for atmosphere- ocean CO2 exchange and thus for climate dynamics on glacial-interglacial time scales: The feedbacks between primary productivity, middle and deep redox conditions, and nutrient recycling from the sediment. We will focus on sediments from two sites representative for the environmental regimes of the Bering Sea, namely open marine Site U1341, and Site U1343 at the continental slope. We will construct inorganic geochemical sediment records (Ba, Fe, P, redox-sensitive trace metals) to trace nutrient, productivity and ocean redox variations over the past 2-5 million years, but also to quantify diagenetic processes that affected primary environmental signals. To evaluate the effects of Pliocene- Pleistocene biogeochemical dynamics and interactions on a more global scale, we will compare our records from the Bering Sea to published data and interpretations from the North Pacific (e.g. ODP Leg 145). In summary, our main research topics are: 1. The development of bioproductivity and related carbon burial.2. The dynamics and coupling of Fe and P under variable redox conditions.3. The effects of early diagenesis on primary geochemical sediment signals.4. The relation between Pliocene-Pleistocene geochemical conditions in the Bering Sea and the North Pacific.