Rates and pathways of carbon oxidation in permanently cold Arctic sediments
Rates and pathways of carbon oxidation in permanently cold Arctic sediments
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DOI：
10.3354/meps180007
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发表时间：
1999-05
影响因子：
2.5
通讯作者：
J. Kostka;B. Thamdrup;R. Glud;D. Canfield
中科院分区：
文献类型：
--
作者：
J. Kostka;B. Thamdrup;R. Glud;D. Canfield
我们在这里报告了北极沉积物中碳矿化速率和途径的综合研究。在斯瓦尔巴群岛的峡湾和挪威沿海的115至329米水深的四个地点进行了研究。斯瓦尔巴群岛沿海地区的特点是海底水温永久寒冷，为-1.7至2.6°C。碳氧化（avg = 20至400 nmol cm -3 d -1）和硫酸盐还原速率（avg = 10至350 nmol cm -3 d -1）在沉积物培养中以高分辨率测量至10 cm深度。通过孔隙水和固相地球化学测定了微生物呼吸氧化剂的分布。通过比较潜在氧化剂的分布与深部综合矿化率，可以量化各种呼吸途径对有机C氧化的重要性。在沉积物孵育中测量的综合C氧化率（11至24 mmol m -2 d -1）与使用底栖着陆器在现场测量的溶解无机碳（DIC）通量相差不到2倍。硫酸盐还原是主要的微生物呼吸途径（占总C氧化的58 - 92%），其次是铁（III）还原（10 - 26%），氧（5 - 14%）和硝酸盐呼吸（2 - 3%）。在以硫酸盐还原为主的沉积物深度，根据独立测量的硫酸盐还原速率计算出的C氧化当量与孵育过程中DIC的生成速率相匹配。沉积物地球化学表明，这些北极沉积物中的氧化剂被还原/呼吸的垂直顺序与同等水深的温带大陆架沉积物相同。永久寒冷的北极沉积物中的微生物群落显示出与温带近岸环境相当的矿化速率和途径。本研究首次完整划分了C氧化途径，显示了硫酸盐呼吸的优势和铁（III）还原对北极沉积物有机质矿化的重要贡献。暴露于相对高碳沉积的冷沉积物中的微生物群落似乎对有机质的输入或可利用性作出反应，而不是对温度作出反应。
We report here a comprehensive study of the rates and pathways of carbon mineralization in Arctic sediments. Four sites were studied at 115 to 329 m water depth in fjords on Svalbard and in coastal Norway. The Svalbard coastal region is characterized by permanently cold bottom water temperatures of -1.7 to 2.6°C. Carbon oxidation (avg = 20 to 400 nmol cm -3 d -1 ) and sulfate reduction rates (avg = 10 to 350 nmol cm -3 d -1 ) were measured at high resolution to 10 cm depth in sediment incubations. The distribution of oxidants available for microbial respiration was determined through porewater and solid phase geochemistry. By comparing the distribution of potential oxidants to the depth-integrated mineralization rates, the importance of various respiratory pathways to the oxidation of organic C could be quantified. Integrated C oxidation rates measured in sediment incubations (11 to 24 mmol m -2 d -1 ) were comparable to within a factor of 2 to dissolved inorganic carbon (DIC) fluxes measured in situ using a benthic lander. Sulfate reduction was the dominant microbial respiration pathway (58 to 92 % of total C oxidation) followed by Fe(III) reduction (10 to 26%), oxygen (5 to 14 %), and nitrate respiration (2 to 3%). At sediment depths where sulfate reduction was dominant, C oxidation equivalents, calculated from independently measured sulfate reduction rates, matched DIC production rates in incubations. Sediment geochemistry revealed that the same vertical sequence of oxidants is reduced/respired in these Arctic sediments as in temperate continental shelf sediments of equivalent water depths. Microbial communities in permanently cold Arctic sediments exhibited mineralization rates and pathways comparable to temperate nearshore environments. This study completely partitioned C oxidation pathways, showing a predominance of sulfate respiration and a substantial contribution of Fe(III) reduction to organic matter mineralization in Arctic sediments for the first time. Microbial communities in cold sediments exposed to relatively high C deposition appear to respond to the input or availability of organic matter rather than to temperature.