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

我们沿海生产或进口的有机物质有很大一部分在海床内退化，这是一个由底栖无脊椎动物介导的过程。这一过程的效率对区域和全球养分和元素的再循环具有重要影响。底栖碳矿化反映了海洋生态系统的生物地球化学和生物条件，很容易测量。最终，沉积物记录中保留的物质与降解的物质的比例调节了我们海洋（和大气）的CO2和O2浓度。最好的和最广泛使用的代用品量化底栖碳矿化是底栖O2交换率。最常见的是，这种速率是通过室内培养或从高分辨率的O2微剖面图中获得的，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。最近，一种新的方法-涡流相关技术-已被引入到水生生物学。这种方法可以量化几平方米海底的海底O2交换率，而且与以前的方法不同，这种方法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，海底O2交换来自于对海床上方少量水中无阻碍的垂直流速和O2浓度的同时快速记录。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底的信号，并且不阻碍调节海底汇率的因素。然而，底栖室确实提供了涡动相关法无法提供的关于底栖动态的详细见解。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。我们建议协调部署的三个海底着陆器类型，以获得海底O2交换率的微传感器，商会和涡相关。前两种着陆器类型将提供给该项目，而后者将在项目内实现。这些测量与在线照相机勘测相配合，以确定海底以及大型和巨型动物群落的特征，将通过沿地形海底结构周围的沿着断面测量，从几毫米（横切微剖面阵列）、dm（室内孵化）、m（通过涡流相关）到公里的空间尺度，详细了解成岩活动的空间变异性。将通过部署1-5天的已开发涡流着陆器和一个横切微型剖面仪，在现场评估海底O2交换率随调节控制（水文、潮汐、浊度、水团交换、光照、动物活动）变化而产生的时间变化。涡流着陆器还将部署在一些硬底环境（珊瑚礁，岩石）中，这些硬底环境通常无法通过腔室和微剖面设备进行评估，以首次将这些常见但很少研究的环境完全纳入沿海碳周转的估计中。

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.