Carbon mineralization of shelf and coastal sediments: A holistic approach using state of the art lander technology and the eddy-correlation technique.

生产或进口到我们沿海海域的有机物质中有很大一部分在海床内被降解，这一过程是由动物无脊椎动物介导的。这一过程的效率对区域和全球的养分和元素回收具有重要意义。底栖生物碳矿化反映了海洋生态系统的生物地球化学和生物条件，可以很容易地测量。最终，沉积记录中保留的物质与被降解的物质的比例调节了我们海洋（和大气）中的二氧化碳和氧气浓度。量化底栖碳矿化的最佳和最广泛使用的替代指标是底栖氧交换速率。这种速率最常见的测量方法是通过室内孵育或从高分辨率O2微剖面中得出，但为了获得可靠的数据，必须通过所谓的着陆器系统直接在海底进行测量。近年来，一种新的研究方法——涡流相关技术被引入到水生生物学中。该方法可以对几平方米海底的底栖生物氧交换率进行量化，并且与以前的方法不同，原则上是非侵入性的，不影响潜在的调节控制（即流体动力学、光、动物活动）。从本质上讲，底栖生物的氧气交换来自于同时快速记录海底上方一小块水中无阻碍的垂直流速和氧气浓度。该技术改编自陆地研究，现在它代表了解决地面和大气（或水域和大气）之间气体交换的常规测量。这种新颖的方法克服了传统方法的主要局限性，通过整合来自大型异质海床的信号，并且不妨碍调节底栖生物交换率的因素。然而，底栖生物室确实提供了关于底栖生物动态的详细见解，这是涡流相关方法所不能提供的。因此，这三种不同的方法是真正互补的，它们共同提供了在生态系统相关尺度上衡量生态系统过程的有力手段。我们建议协调部署三种底栖着陆器类型，通过微传感器、腔室和涡流相关来获得底栖氧气交换率。前两种着陆器将提供给该项目，而后一种着陆器将在该项目中实现。与描述海底和大型动物群落特征的在线相机调查相补充，这些测量将提供关于成岩活动的空间变异性的详细见解，从几毫米（横切微剖面阵列）、dm（室内孵化）、m（涡流相关）到km（通过沿着地形海底结构周围的横切测量）的空间尺度。由调节控制（水文、潮汐、浊度、水团交换、光线、动物活动）的变化引起的底栖生物氧交换率的时间变化将通过部署已开发的涡流着陆器和横切微剖面仪1-5天在现场进行评估。涡流着陆器还将被部署在一些硬底环境（珊瑚礁、岩石）中，这些环境通常不能被室和微分析设备评估，这是第一次在估计沿海碳周转时完全包括这些常见但很少研究的环境。

A significant fraction of the organic material produced or imported to our coastal seas is degraded within the sea-bed, a process mediated by infaunal invertebrates. The efficiency of this process has important implications for regional and global nutrient and element recycling. Benthic carbon mineralization represents the biogeochemical and biological conditions of marine ecosystems and can be readily measured. Ultimately, the fraction of material retained in the sediment record versus being degraded, regulates the CO2 and O2 concentration of our oceans (and atmosphere). The best and most widely used proxy for quantifying the benthic carbon mineralization is the benthic O2 exchange rate. Most commonly such rates are measured by chamber incubations or derived form high-resolution O2 microprofiles but, to obtain reliable data, measurements have to be performed directly at the seabed by so-called lander systems. Recently a new approach - the eddy-correlation technique - has been introduced to aquatic biology. The approach allows benthic O2 exchange rates to be quantified for several m2 of seabed and, unlike previous methodologies, is in principle non-invasive and does not affect potential regulating controls (i.e. hydrodynamics, light, fauna activity). In essence, the benthic O2 exchange is derived from simultaneous, rapid recordings of the unobstructed vertical current velocity and O2 concentrations in a small volume of water above the seabed. The technique is adapted from terrestrial research where it now represents a routine measurement for resolving gas exchange between ground and atmosphere (or aquatic areas and atmosphere). This novel approach overcomes the primary limitations of traditional approaches by integrating the signal from a large heterogeneous seabed and by not obstructing factors regulating the benthic exchange rates. Benthic chambers do, however, offer detailed insight on the benthic dynamic that not can be provided by the eddy-correlation approach. The three different approaches are thus truly complementary and together they provide powerful means of measuring ecosystem processes at ecosystem relevant scale. We propose concerted deployments of three benthic lander types to obtain benthic O2 exchange rates by microsensors, chambers and eddy-correlation. The two first lander types will be made available to the project while the latter will be realized within the project. Complemented with online camera surveys for characterizing the seabed and the macro- and mega fauna communities the measurements will provide detailed insight in the spatial variability of diagenetic activity from spatial scales of a few mm (transecting microprofile arrays), dm (chamber incubations), m (by eddy-correlation) to km by measuring along transects around topographic seabed structures. Temporal variations in benthic O2 exchange rates as induced by variations in regulating controls (hydrography, tide, turbidity, exchange of water masses, light, fauna activity) will be evaluated, in situ, by 1-5 days deployments of the developed eddy-lander and a transecting microprofiler. The eddy-lander will also be deployed in a number of hard-bottom environments (reefs, rocks) that generally not are assessable for chamber and microprofiling equipment to, for the first time, fully include these common, but rarely studied environments in estimates for coastal carbon turn over.