Experimental studies of the deep turbid layer in the Black Sea

Prokhorenko, Yu. A.; Krasheninnikov, B. N.; Agafonov, E. A.; Basharin, V. A.

doi:10.1007/bf02197511

Cited by 8 publications

(7 citation statements)

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“…2). This specific feature is known from other anoxic basins like the Black Sea and is most likely caused by the precipitation of iron and manganese oxides (Kempe et al, 1991) and an enrichment of particulate organic matter (POM) due to enhanced microbial activity (Prokhorenko et al, 1994). The concentrations of H 2 S and other reduced chemical species like ammonium (NH + 4 ) are constantly increasing with depth, indicating an upward flux from the sediment or deep water towards the redox-zone .…”

Section: Physical Parameters and Gas Chemistrymentioning

confidence: 87%

Aerobic methanotrophy within the pelagic redox-zone of the Gotland Deep (central Baltic Sea)

Schmale

Blumenberg²,

Kießlich

et al. 2012

Biogeosciences

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Abstract. Water column samples taken in summer 2008 from the stratified Gotland Deep (central Baltic Sea) showed a strong gradient in dissolved methane concentrations from high values in the saline deep water (max. 504 nM) to low concentrations in the less dense, brackish surface water (about 4 nM). The steep methane-gradient (between 115 and 135 m water depth) within the redox-zone, which separates the anoxic deep part from the oxygenated surface water (oxygen concentration 0-0.8 mL L −1 ), implies a methane consumption rate of 0.28 nM d −1 . The process of microbial methane oxidation within this zone was evident by a shift of the stable carbon isotope ratio of methane between the bottom water (δ 13 C CH 4 = −82.4 ‰) and the redoxzone (δ 13 C CH 4 = −38.7 ‰). Water column samples between 80 and 119 m were studied to identify the microorganisms responsible for the methane turnover in that depth interval. Notably, methane monooxygenase gene expression analyses for water depths covering the whole redox-zone demonstrated that accordant methanotrophic activity was probably due to only one phylotype of the aerobic type I methanotrophic bacteria. An imprint of these organisms on the particular organic matter was revealed by distinctive lipid biomarkers showing bacteriohopanepolyols and lipid fatty acids characteristic for aerobic type I methanotrophs (e.g., 35-aminobacteriohopane-30,31,32,33,34-pentol), corroborating their role in aerobic methane oxidation in the redox-zone of the central Baltic Sea.

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Section: Physical Parameters and Gas Chemistrymentioning

confidence: 87%

Aerobic methanotrophy within the pelagic redox-zone of the Gotland Deep (central Baltic Sea)

Schmale

Blumenberg²,

Kießlich

et al. 2012

Biogeosciences

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“…It is often explained by the diffusion of reduced chemical species across the redox zone, which lead to the precipitation of metal oxides (e.g., oxides of Fe and Mn) or the oxidation of H 2 S to elemental sulfur S 0 (Dellwig et al, 2010;Kamyshny et al, 2013). Another theory is that the energy-rich compounds transported from the anoxic zone across the chemocline increase microbial turnover of matter and thus the abundance of bacteria in a discrete depth interval (Prokhorenko et al, 1994;Dellwig et al, 2010;Labrenz et al, 2010). However, the distribution pattern can also be used to discuss the stability of that chemical boundary as lateral intrusions of external water masses into the redox zone will perturb the established chemical stratification (Kamyshny et al, 2013) and may inject O 2 / H 2 S enriched water into this specific depth interval (Dellwig et al, 2012).…”

Section: Lateral Intrusionsmentioning

confidence: 99%

Comparative studies of pelagic microbial methane oxidation within the redox zones of the Gotland Deep and Landsort Deep (central Baltic Sea)

et al. 2013

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Abstract. Pelagic methane oxidation was investigated in dependence on differing hydrographic conditions within the redox zone of the Gotland Deep (GD) and Landsort Deep (LD), central Baltic Sea. The redox zone of both deeps, which indicates the transition between oxic and anoxic conditions, was characterized by a pronounced methane concentration gradient between the deep water (GD: 1233 nM, 223 m; LD: 2935 nM, 422 m) and the surface water (GD and LD < 10 nM). This gradient together with a 13 C CH 4 enrichment (δ 13 C CH 4 deep water: GD −84 ‰, LD −71 ‰; redox zone: GD −60 ‰, LD −20 ‰; surface water: GD −47 ‰, LD −50 ‰; δ 13 C CH 4 vs. Vienna Pee Dee Belemnite standard), clearly indicating microbial methane consumption within the redox zone. Expression analysis of the methane monooxygenase identified one active type I methanotrophic bacterium in both redox zones. In contrast, the turnover of methane within the redox zones showed strong differences between the two basins (GD: max. 0.12 nM d −1 , LD: max. 0.61 nM d −1 ), with a nearly four-times-lower turnover time of methane in the LD (GD: 455 d, LD: 127 d). Vertical mixing rates for both deeps were calculated on the base of the methane concentration profile and the consumption of methane in the redox zone (GD: 2.5 × 10 −6 m 2 s −1 , LD: 1.6 × 10 −5 m 2 s −1 ). Our study identified vertical transport of methane from the deep-water body towards the redox zone as well as differing hydrographic conditions (lateral intrusions and vertical mixing) within the redox zone of these deeps as major factors that determine the pelagic methane oxidation.

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“…The regression analysis carried out using the observational data from separate expeditionary voyages during summer-autumn periods in 1984-1986 demonstrated the rather close linear relationship between Ze max and the depth of the upper boundary of hydrogen sulfide zone (r = 0.6-0.89) [15].…”

Section: Resultsmentioning

confidence: 94%

“…The consideration of the relationship between Ze max and the depth of the lower upper boundary of hydrogen sulfide zone is of separate interest. This is associated both with the need in obtaining the seasonal estimates of such relationship in different dynamic formations and with specifying the nature of formation of the deep turbid layer [2,15] (including the effects of processes in the hydrogen sulfide zone).…”

Section: Resultsmentioning

confidence: 99%

Effects of the distribution of hydrological and hydrobiological parameters on the structure of transparency field in the upper layer of the Black Sea pelagic zone

Kukushkin

2013

Russ. Meteorol. Hydrol.

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Considered are the effects of suspended matter content and water mass dynamics on the formation of optical structure of water in the upper layer of the deep part of the Black Sea using the data of long-term simultaneous observations. It is demonstrated that the peculiarities of horizontal distribution of the depth of transparent and turbid optical layers depend on the distribution of hydrological parameters characterizing the dynamic processes in the upper layer of the sea. Computed and analyzed are the parameters of regression relationship between the beam attenuation coefficient and the concentration of organic and total suspension and chlorophyll-a as well as between the depth of transparent layer and the position of the lower boundary of cold intermediate layer in different dynamic formations in spring, summer, and autumn.

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Experimental studies of the deep turbid layer in the Black Sea

Cited by 8 publications

References 0 publications

Aerobic methanotrophy within the pelagic redox-zone of the Gotland Deep (central Baltic Sea)

Aerobic methanotrophy within the pelagic redox-zone of the Gotland Deep (central Baltic Sea)

Comparative studies of pelagic microbial methane oxidation within the redox zones of the Gotland Deep and Landsort Deep (central Baltic Sea)

Effects of the distribution of hydrological and hydrobiological parameters on the structure of transparency field in the upper layer of the Black Sea pelagic zone

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