Sedimentation dynamics and microbial degradation of marine aggregates: hydrodynamic fundamentals of particulate carbon transport in the ocean

海洋团聚体是海洋生物碳泵的重要组成部分，通过沉积作用将颗粒有机碳输出到深水层。我们的目标是构建一个流体动力学-微生物联合项目，以表征海洋团聚体的有效垂直迁移，特别强调团聚体中微生物的周转率。通过将实验室实验与数值模拟相结合，我们首先将聚集体的下沉速度参数化为环境流体的尺寸、孔隙度、成分和密度分层的函数。接下来，间质液和环境水之间的传质以及聚集体内的微生物周转率将被确定为下沉速度的函数。 在此基础上，将开发一个数学模型，可靠地模拟下沉速度和质量传递。 这样的模型将使我们能够第一次提供生物碳泵效率的现实估计。此外，该模型提供了宝贵的投入和方法，将海洋过程纳入现有的全球气候和海洋碳循环模型。

Marine aggregates build the backbone of biological carbon pump in the ocean by exporting the particulate organic carbon into the deeper water layers via sedimentation.We target at constructing a combined hydrodynamic-microbiological project for characterization of effective vertical transport by marine aggregates with special emphasis on microbial turnover rates within the aggregates. By combining the laboratory experiments with numerical simulations, we first parametrize the sinking velocity of the aggregates as a function of size, porosity, composition and density stratification of the ambient fluid. Next, the mass transfer between the interstitial fluid and the ambient water as well as the microbial turnover rates within the aggregates will be determined as a function of sinking velocity. Based on this, a mathematical model will be developed which mimics reliably the sinking velocity and mass transfer. Such a model will enable us for the first time to provide a realistic estimation of the efficiency of the biological carbon pump. Furthermore, the model delivers valuable inputs and approaches to integrate marine processes into available global climate and oceanic carbon circulation models.