Sulfur and carbon in mIcrobial processes in waters and sediments of the Kara Sea in September 2007

Results of microbiological, biogeochemical and isotope geochemical studies in the Kara Sea are described. Samples for these studies were obtained during Cruise 54 of R/V Akademik Mstislav Keldysh in September 2007. The studied area covered the northern, central, and southwestern parts of the Kara Sea and the Obskaya Guba (Ob River estuary). Quantitative characteristics of total bacterial population and activity of microbial processes in the water column and bottom sediments were obtained. Total abundance of bacterioplankton (BP) varied from 250000 cells/ml in the northern Kara Sea to 3000000 cells/ml in the Obskaya Guba. BP abundance depended on concentration of suspensded matter. Net BP production was minimal in the central Kara Sea (up to 0.15-0.2 µg C/l/day) and maximal (0.5-0.75 µg C/l/day) in the Obskaya Guba. Organic material at the majority of stations at the Ob transect predominantly contained light carbon isotopes (-28.0 to -30.18 per mil) of terrigenous origin. Methane concentration in the surface water layer varied from 0.18 to 2.0 µl CH4/l, and methane oxidation rate varied from 0.1 to 100 nl CH4/l/day. Methane concentration in the upper sediment layer varied from 30 to 300 µl CH4/dm**3; rate of methane formation was varied from 44 to 500 nl CH4/dm**3/day and rate of methane oxidation - from 30 to 2000 nl CH4/dm**3/day. Rate of sulfate reduction varied from 4 to 184 µg S/dm**3/day.

本数据集记述了喀拉海（Kara Sea）的微生物学、生物地球化学及同位素地球化学研究成果。本研究的样品采集于2007年9月「姆斯季斯拉夫·凯尔迪什院士号」（R/V Akademik Mstislav Keldysh）第54次科考航次。研究区域涵盖喀拉海北部、中部、西南部区域以及鄂毕湾（Obskaya Guba，鄂毕河入海口）。本次研究获取了水体及海底沉积物中总细菌群落数量与微生物过程活性的定量表征数据。浮游细菌（bacterioplankton, BP）的总丰度范围为250000 cells/ml（喀拉海北部）至3000000 cells/ml（鄂毕湾）。浮游细菌丰度与悬浮颗粒物浓度相关。浮游细菌净生产力在喀拉海中部最低，仅为0.15~0.2 μg C/(L·d)，在鄂毕湾最高，可达0.5~0.75 μg C/(L·d)。鄂毕断面多数站位的有机质主要源自陆源，其碳同位素组成偏轻，δ¹³C值介于-28.0‰至-30.18‰之间。表层水体的甲烷浓度范围为0.18~2.0 μl CH₄/L，甲烷氧化速率范围为0.1~100 nl CH₄/(L·d)。表层沉积物的甲烷浓度范围为30~300 μl CH₄/dm³；甲烷生成速率范围为44~500 nl CH₄/(dm³·d)，甲烷氧化速率范围为30~2000 nl CH₄/(dm³·d)。硫酸盐还原速率范围为4~184 μg S/(dm³·d)。