Impact of lateral intrusions and mixing on the biogeochemistry and microbiology of pelagic redoxclines

在层结稳定、水交换减少的沿海和边缘海，经常观察到深水缺氧的现象。所谓的氧化还原跃层，在缺氧层的顶部，在这种条件下发展，其特征是强烈的生物地球化学梯度，这是一些重要的微生物介导的元素转化的位置。在这里，我们的项目假设是，快速和间歇性修改的本地生物地球化学和微生物的条件与横向入侵，特别是由于入侵和周围沃茨之间的湍流混合，构成了氧化还原跃层系统的重要组成部分。我们计划研究水文，湍流混合，地球化学过程和微生物活动之间的这种联系，以波罗的海中部与其定义明确的氧化还原跃层为例。最近建立的自主分析系统在波罗的海中部将提供高分辨率的数据，使我们能够确定的水文，地球化学和混合参数的长期变化与入侵。将在船舶航行期间调查混合对微生物活动和群落的影响，结合对混合参数的观察以及代表性的生物地球化学和微生物转化过程。

In coastal and marginal seas with stable stratification and reduced water exchange, hypoxic deep-water conditions are a frequently observed phenomenon. The so-called redoxcline, developing under such conditions at the top of the anoxic layer, is characterized by strong biogeochemical gradients, which are the location of some important microbially mediated element transformations. Here, our project hypothesis is that the rapid and intermittent modification of the local biogeochemical and microbiological conditions associated with lateral intrusions, in particular due to turbulent mixing between intrusions and ambient waters, constitutes an essential component of the redoxcline system. We plan to study this link between hydrography, turbulent mixing, biogeochemical processes, and microbial activities, taking the central Baltic Sea with its well-defined redoxcline as an example. A recently established autonomous profiling system in the Central Baltic Sea will provide high-resolution data, allowing us to determine the long-term variability of hydrographic, biogeochemical, and mixing parameters associated with the intrusions. The impact of mixing for the microbial activities and communities will be investigated during ship cruises, combining observations of mixing parameters, and representative biogeochemical and microbial transformation processes.