Diesing Markus, Kröger Silke, Parker Ruth, Jenkins Chris, Mason Claire, Weston Keith
1Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, Suffolk, NR33 0HT UK.
2Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309-0450 USA.
Biogeochemistry. 2017;135(1):183-200. doi: 10.1007/s10533-017-0310-4. Epub 2017 Feb 15.
Shelf seas and their associated benthic habitats represent key systems in the global carbon cycle. However, the quantification of the related stocks and flows of carbon are often poorly constrained. To address benthic carbon storage in the North-West European continental shelf, we have spatially predicted the mass of particulate organic carbon (POC) stored in the top 10 cm of shelf sediments in parts of the North Sea, English Channel and Celtic Sea using a Random Forest model, POC measurements on surface sediments from those seas and relevant predictor variables. The presented model explains 78% of the variance in the data and we estimate that approximately 250 Mt of POC are stored in surficial sediments of the study area (633,000 km). Upscaling to the North-West European continental shelf area (1,111,812 km) yielded a range of 230-882 Mt of POC with the most likely estimate being on the order of 476 Mt. We demonstrate that the largest POC stocks are associated with coarse-grained sediments due to their wide-spread occurrence and high dry bulk densities. Our results also highlight the importance of coastal sediments for carbon storage and sequestration. Important predictors for POC include mud content in surficial sediments, annual average bottom temperature and distance to shoreline, with the latter possibly a proxy for terrestrial inputs. Now that key variables in determining the spatial distribution of POC have been identified, it is possible to predict future changes to the POC stock, with the presented maps providing an accurate baseline against which to assess predicted changes.
陆架海及其相关的底栖生境是全球碳循环中的关键系统。然而，对相关碳储量和碳流量的量化往往受到很大限制。为了研究西北欧大陆架的底栖碳储存情况，我们利用随机森林模型、对北海、英吉利海峡和凯尔特海部分海域表层沉积物的颗粒有机碳（POC）测量数据以及相关预测变量，对这些海域部分区域陆架沉积物顶部10厘米内储存的颗粒有机碳质量进行了空间预测。所呈现的模型解释了数据中78%的方差，我们估计研究区域（633,000平方千米）的表层沉积物中大约储存了250百万吨颗粒有机碳。将范围扩大到西北欧大陆架区域（1,111,812平方千米）后，颗粒有机碳储量在230 - 882百万吨之间，最可能的估计约为476百万吨。我们证明，最大的颗粒有机碳储量与粗粒沉积物有关，这是因为粗粒沉积物分布广泛且干容重较高。我们的研究结果还凸显了海岸沉积物对于碳储存和固存的重要性。颗粒有机碳的重要预测指标包括表层沉积物中的泥质含量、年平均底层温度以及与海岸线的距离，其中后者可能是陆地输入的一个替代指标。既然已经确定了决定颗粒有机碳空间分布的关键变量，那么就有可能预测颗粒有机碳储量的未来变化，本文所呈现的地图提供了一个准确的基线，可据此评估预测的变化情况。
