Carbon mineralization in Laptev and East Siberian sea shelf and slope sediment
Carbon mineralization in Laptev and East Siberian sea shelf and slope sediment
复制标题
DOI：
10.5194/bg-15-471-2018
复制
发表时间：
2018-01-25
期刊：
影响因子：
4.9
通讯作者：
Samarkin, Vladimir A.
中科院分区：
文献类型：
--
作者：
Bruchert, Volker;Broder, Lisa;Samarkin, Vladimir A.
西伯利亚北极海陆棚和陆坡是从西伯利亚富含有机碳的永久冻土区输送的陆地有机物质降解的关键区域。我们报告沉积物碳矿化率的基础上O-2微电极分析;完整的沉积物核心孵化; S-35-硫酸盐示踪实验;孔隙水溶解无机碳（DIC）;三角洲（DIC）-D-13 C;和铁，锰，铵浓度从20架和斜坡站。该数据集提供了一个空间概况的沉积物碳矿化率和途径外拉普捷夫和东西伯利亚北极大陆架和斜坡的大部分，使我们能够评估这些沉积物中的碳埋藏的降解速率和效率。氧的吸收率和铁和锰的还原率与温带大陆架和斜坡环境相当，但细菌硫酸盐还原率相对较低。在最上层的50厘米的沉积物中，有氧碳矿化占主导地位的降解，平均包括84%的深度综合碳矿化。氧的吸收速率和厌氧碳矿化率较高，在东西伯利亚海陆架东部相比，拉普捷夫海陆架。孔隙沃茨中DIC /NH 4+比值和溶解DIC的稳定碳同位素组成表明，西伯利亚陆棚和陆坡的降解有机质为海陆混合有机质。基于双端元计算，陆地有机碳的贡献在32%和36%之间变化，在拉普捷夫海的贡献高于东西伯利亚海。在拉普捷夫海和东西伯利亚海的外大陆架上使用同位素端元分配法外推测得的降解速率表明，外大陆架海底沉积物中的呼吸量约为16 Tg C yr（-1）。埋在氧气渗透深度以下的有机物中，0.6至1.3 Tg C yr（-1）之间的有机物通过厌氧过程降解，陆地有机碳的贡献范围在0.3至0.5 Tg yr（-1）之间。
The Siberian Arctic Sea shelf and slope is a key region for the degradation of terrestrial organic material transported from the organic-carbon-rich permafrost regions of Siberia. We report on sediment carbon mineralization rates based on O-2 microelectrode profiling; intact sediment core incubations; S-35-sulfate tracer experiments; pore-water dissolved inorganic carbon (DIC); delta(DIC)-D-13C; and iron, manganese, and ammonium concentrations from 20 shelf and slope stations. This data set provides a spatial overview of sediment carbon mineralization rates and pathways over large parts of the outer Laptev and East Siberian Arctic shelf and slope and allows us to assess degradation rates and efficiency of carbon burial in these sediments. Rates of oxygen uptake and iron and manganese reduction were comparable to temperate shelf and slope environments, but bacterial sulfate reduction rates were comparatively low. In the topmost 50 cm of sediment, aerobic carbon mineralization dominated degradation and comprised on average 84% of the depth-integrated carbon mineralization. Oxygen uptake rates and anaerobic carbon mineralization rates were higher in the eastern East Siberian Sea shelf compared to the Laptev Sea shelf. DIC / NH4+ ratios in pore waters and the stable carbon isotope composition of remineralized DIC indicated that the degraded organic matter on the Siberian shelf and slope was a mixture of marine and terrestrial organic matter. Based on dual end-member calculations, the terrestrial organic carbon contribution varied between 32 and 36 %, with a higher contribution in the Laptev Sea than in the East Siberian Sea. Extrapolation of the measured degradation rates using isotope end-member apportionment over the outer shelf of the Laptev and East Siberian seas suggests that about 16 Tg C yr(-1) is respired in the outer shelf seafloor sediment. Of the organic matter buried below the oxygen penetration depth, between 0.6 and 1.3 Tg C yr(-1) is degraded by anaerobic processes, with a terrestrial organic carbon contribution ranging between 0.3 and 0.5 Tg yr(-1).