Developing a Global Perspective on Dynamics of Riverine Transfer of Terrestrial Biospheric Carbon to the Ocean

在短时间内，土壤和植被等大型“活性”碳库之间交换率的微小变化可以显著影响大气CO2库的大小。因此，为了预测当前大气CO2增加和伴随的全球变暖的生态和地球化学后果，我们需要了解这些碳库之间的碳交换的自然过程。这方面的一个关键方面是气候与陆地生物圈碳循环动态之间在全球范围内的相互作用。特别是，我们对陆地上维管植物固定的碳输出到海洋的时间尺度只有非常初步的了解-这是碳循环的关键组成部分。在这个项目中，伍兹霍尔海洋研究所的研究人员将开始建立一个关于河流输出的不同陆地有机碳（OC）成分年龄的全球数据库。 重点将是在颗粒OC池内输出的陆地生物圈碳，因为它在全球碳循环中具有举足轻重的作用，可能对气候变化和人类活动等快速扰动更敏感，并在大陆边缘沉积物记录中留下遗产，可以检索古气候重建。 该小组将研究河流排入海洋的陆地生物圈碳的组成，方法是确定在河流终点附近收集的悬浮沉积物以及三角洲沉积物和内陆架洪水沉积物的特征。他们将尝试将放射性碳（14 C）测量在不同的水平-从散装OC到特定的分子（生物标志物）-以限制生物圈OC池的不同成分的年龄和相对比例。 他们希望通过检查各种河流排放的维管植物来源的碳的年龄特征来获得陆地生物圈OC输出到海洋的动态的全球图像，这些河流在流域大小，海拔，纬度和物质通量方面存在显着差异。具体而言，他们将（1）评估河流维管植物源OC的年龄与河流出口纬度之间观察到的初步关系的稳健性，（2）更精确地定义这种关系的性质，（3）检查生物圈OC池的不同组成部分是否存在类似的关系，最后，（4）利用这些研究成果，探讨全球尺度上河流入海生物圈碳年龄的控制机制，进而了解OC循环与区域和全球气候的相互作用。更广泛的影响：这项研究计划基本上是基于一种合作的方法，将利用大量的美国，中国和欧洲的同事谁是参与河流研究地球仪共享的样本和知识。这一奋进产生的出版物将反映这些合作伙伴关系。该项目将为WHOI的博士后科学家提供合作研究、培训和学习环境。该项目产生的数据将输入目前正在汇编的遗留数据库。这些数据将通过出版物、专门网站以及与其他可在网上访问的社区数据库的链接与社区共享。

Over short timescales, small changes in the rate of exchange between large pools of "active" carbon such as soils and vegetation can significantly impact the size of the atmospheric CO2 reservoir. Therefore, to predict the ecological and biogeochemical consequences of the current atmospheric CO2 increase and concomitant global warming, we need to understand the natural processes of carbon exchange between these carbon reservoirs. A key aspect in this regard is the global-scale interaction between climate and the dynamics of terrestrial biospheric carbon cycling. In particular, we have only a very rudimentary understanding of the timescales over which carbon fixed by vascular plants on land is exported to the oceans - a crucial component of the carbon cycle. In this project, researchers at the Woods Hole Oceanographic Institution will begin to build a global database on the age of different terrestrial organic carbon (OC) constituents exported by rivers. The focus will be on terrestrial biospheric carbon exported within the particulate OC pool because it has a pivotal role in the global carbon cycle, is potentially the more sensitive to rapid perturbations such as climate change and anthropogenic activity, and leaves a legacy within continental margin sediment records that can be retrieved for paleoclimate reconstructions. The team will study the composition of terrestrial biospheric carbon discharged by rivers to the oceans by characterizing suspended sediments collected close to the terminus of the rivers, as well as deltaic deposits and inner shelf flood deposits. They will attempt to couple radiocarbon (14C) measurements at different levels - from bulk OC to specific molecules (biomarkers) - in order to constrain the age and relative proportion of the different constituents of the biospheric OC pool. They expect to derive a global picture of the dynamics of terrestrial biospheric OC export to the ocean by examining age characteristics of vascular plant-derived carbon discharged by a wide range of rivers that differ markedly in terms of drainage basin size, elevation, latitude, and materials flux. Specifically, they will (1) evaluate the robustness of the preliminary relationship observed between the age of riverine vascular plant-derived OC and the latitude of the river outlet, (2) more precisely define the nature of this relationship, (3) examine whether similar relationships holds for different components of the biospheric OC pool, and finally, (4) use these findings to explore the mechanisms controlling the age of the biospheric carbon discharged by rivers to the ocean at the global scale, and hence to derive insights into the interactions between OC cycling and regional and global climate. Broader impacts: This research initiative is fundamentally based on a collaborative approach that will utilize samples and knowledge shared by a large number of American, Chinese, and European colleagues who are involved in river studies all around the globe. The publications arising from this endeavor will reflect these collaborative partnerships. The project will provide a collaborative research, training and learning environment for a postdoctoral scientist at WHOI. Data emanating from the project will be contributed to a legacy database that is currently being compiled. The data will be shared with the community through publications, through a dedicated website, as well as by linking to other web-accessible community databases.