Particulate geochemistry of sediment core AL561_7-1

The AL561 cruise was conducted in the framework of the project APOC ("Anthropogenic impacts on Particulate Organic Carbon cycling in the North Sea"). This collaborative project between GEOMAR, AWI, HEREON, UHH, and BUND is to understand how particulate organic carbon (POC) cycling contributes to carbon sequestration in the North Sea and how this ecosystem service is compromised and interlinked with global change and a range of human pressures include fisheries (pelagic fisheries, bottom trawling), resource extraction (sand mining), sediment management (dredging and disposal of dredged sediments) and eutrophication. The main aim of the sampling activity during AL561 cruise was to recover undisturbed sediment from high accumulation sites in the Skagerrak/Kattegat and to subsample sediment/porewater at high resolution in order to investigate sedimentation transport processes, origin of sediment/POC and mineralization processes over the last 100- 200 years. Moreover, the actual processes of sedimentation and POC degradation in the water column and benthic layer will be addressed by sampling with CTD and Lander devices. In total 9 hydroacoustic surveys (59 profiles), 4 Gravity Corer, 7 Multicorer, 3 BIGO Lander and 3 CTD stations were successfully conducted during the AL561 cruise.

AL561航次依托APOC项目（"Anthropogenic impacts on Particulate Organic Carbon cycling in the North Sea"，北海水体颗粒有机碳循环的人为影响）框架开展。该合作项目由GEOMAR、AWI、HEREON、UHH与BUND联合发起，旨在阐明颗粒有机碳（Particulate Organic Carbon, POC）循环对北海水域碳封存的贡献机制，以及该生态系统服务如何受全球变化与一系列人类活动压力影响并与之相互关联，相关人类活动包括渔业（中上层渔业、底拖网捕捞）、资源开采（采砂作业）、沉积物管理（疏浚及疏浚物处置）与富营养化。
AL561航次采样活动的核心目标为在斯卡格拉克海峡/卡特加特海域的高沉积速率站位获取未受扰动的沉积物，并以高分辨率对沉积物/孔隙水进行分样，以此解析近100至200年间的沉积物搬运过程、沉积物与POC的来源及矿化作用机制。此外，本航次还将通过温盐深仪（CTD）与着陆器设备开展采样，以探究水柱与底栖层内的实际沉积过程及POC降解机制。
AL561航次共顺利完成9条水声调查航线（含59条测线）、4个重力取芯器站位、7个多管采样器站位、3个BIGO着陆器站位及3个CTD站位。