Anna Silyakova

HUB Ocean

The rapid warming of the Arctic-Boreal region has led to the concern that large amounts of methane may be released to the atmosphere from its carbon-rich soils, as well as subsea permafrost, amplifying climate change. In this review, we assess the various sources and sinks of methane from northern high latitudes, in particular those that may be enh...

The main goal of CAGE 15-­2 cruise was to study the gas hydrate system and methane emissions off western Svalbard and in Storfjordrenna. We addressed this through a comprehensive scientific program comprising dives with the MISO-­‐Tow Cam adapted to the multicorer frame from UiT-­‐NPI (TowCam/Multicorer, TCM), methane measurements in sediments and...

The cruise had two main objectives: Deployment of the two CAGE ocean floor observatories (OS1 and OS2) at shallow PKF site and deeper PKF site; CAGE ocean floor observatories were designed and build as collaborative work of CAGE scientists with Kongsberg engineers. Observatories have identical set up except that only one of them have side looking m...

We examine an Arctic winter storm event, which led to ice break–up, the formation of open leads, and the subsequent freezing of these leads. The methane (CH4) concentration in under–ice surface water before and during the storm event was 8–12 nmol L⁻¹, which resulted in a potential sea–to–air CH4 flux ranging from +0.2 to +2.1 mg CH4 m⁻² d⁻¹ in ope...

Hydrothermal vents modify and displace subsurface dissolved organic matter (DOM) into the ocean. Once in the ocean, this DOM is transported together with elements, particles, dissolved gases and biomass along with the neutrally buoyant plume layer. Considering the number and extent of actively venting hydrothermal sites in the oceans, their contrib...

Improved quantification techniques of natural sources are needed to explain variations in atmospheric methane. In polar regions, high uncertainties in current estimates of methane release from the seabed remain. We present unique 10- and 3-month time series of bottom water measurements of physical and chemical parameters from two autonomous ocean o...

Hydrothermal vents modify and displace subsurface dissolved organic matter (DOM) into the ocean. Once in the ocean, this DOM is transported together with elements, particles, dissolved gases, and biomass along with the neutrally buoyant plume layer. Considering the number and extent of actively venting hydrothermal sites in the oceans, their contri...

Improved quantification techniques of natural sources is needed to explain variations in atmospheric methane. In polar regions, high uncertainties in current estimates of methane release from the seabed remain. We present two unique 10 and 3 months long time-series of bottom water measurements of physical and chemical parameters from two autonomous...

The Arctic Ocean subseabed holds vast reservoirs of the potent greenhouse gas methane (CH 4), often seeping into the ocean water column. In a continuously warming ocean as a result of climate change an increase of CH 4 seepage from the seabed is hypothesized. Today, CH 4 is largely retained in the water column due to the activity of methane-oxidizi...

Dissociating gas hydrates, submerged permafrost, and gas bearing sediments release methane to the water column from a multitude of seeps in the Arctic Ocean. The seeping methane dissolves and supports the growth of aerobic methane oxidizing bacteria (MOB), but the effect of seepage and seep related biogeochemical processes on water column dissolved...

We investigate methane seepage on the shallow shelf west of Svalbard during three consecutive years, using discrete sampling of the water column, echosounder-based gas flux estimates, water mass properties, and numerical dispersion modelling. The results reveal three distinct hydrographic conditions in spring and summer, showing that the methane co...

Methane (CH4) in marine sediments has the potential to contribute to changes in the ocean and climate system. Physical and biochemical processes that are difficult to quantify with current standard methods such as acoustic surveys and discrete sampling govern the distribution of dissolved CH4 in oceans and lakes. Detailed observations of aquatic CH...

Methane (CH4) in marine sediments has the potential to contribute to changes in the ocean- and climate system. Physical and biochemical processes that are difficult to quantify with current standard methods such as acoustic surveys and discrete sampling govern the distribution of dissolved CH4 in oceans and lakes. Detailed observations of aquatic C...

We present a marine two‐phase gas model in one dimension (M2PG1) resolving interaction between the free and dissolved gas phases and the gas propagation toward the atmosphere in aquatic environments. The motivation for the model development was to improve the understanding of benthic methane seepage impact on aquatic environments and its effect on...

Methane (CH4) is a powerful greenhouse gas. Its atmospheric mixing ratios have been increasing since 2005. Therefore, quantification of CH4 sources is essential for effective climate change mitigation. Here we report observations of the CH4 mixing ratios measured at the Zeppelin Observatory (Svalbard) in the Arctic and aboard the research vessel (R...

Methane (CH4) is a powerful greenhouse gas and atmospheric mixing ratios have been increasing since 2005. Therefore, quantification of CH4 sources is essential for effective climate change mitigation. Here we report observations of the CH4 mixing ratios measured at Zeppelin Observatory (Svalbard) in the Arctic and aboard the Research Vessel (RV) He...

Rare CO2 flux measurements from Arctic pack ice show that two types of ice contribute to the release of CO2 from the ice to the atmosphere during winter and spring: young, thin ice with a thin layer of snow and older (several weeks), thicker ice with thick snow cover. Young, thin sea ice is characterized by high salinity and high porosity, and snow...

Rare CO2 flux measurements from Arctic pack ice show that two types of ice contribute to the release of CO2 from the ice to the atmosphere during winter and spring: young, thin ice with a thin layer of snow and older (several weeks), thicker ice with thick snow cover. Young, thin sea ice is characterized by high salinity and high porosity, and snow...

Methods  Methane emanates from gas bearing sediments into the water column through a number of seeps in the Arctic Ocean 1 , but methane driven processes remain poorly understood  The goal of this study is to investigate changes in DOM compositions, nutrient regime and biochemical properties of the water column under the influence of methane driv...

Greenhouse gas methane trapped in sub-seafloor gas hydrates may play an important role in a potential climate feedback system. The impact of future Arctic Ocean warming on the hydrate stability and its contribution to atmospheric methane concentrations remains an important and unanswered question. Here, we estimate the climate impact of released me...

Cold seeps can support unique faunal communities via chemosynthetic interactions fueled by seabed emissions of hydrocarbons. Additionally, cold seeps can enhance habitat complexity at the deep-sea floor through the accretion of methane derived authigenic carbonates (MDAC). We examined infaunal and megafaunal community structure at high-Arctic cold...

The impacts of oceanic CO2 uptake and global warming on the surface ocean environment have received substantial attention, but few studies have focused on shelf bottom water, despite its importance as habitat for benthic organisms and demersal fisheries such as cod. We used a downscaling ocean biogeochemical model to project bottom water acidificat...

Significance Shallow Arctic Ocean gas hydrate reservoirs experienced distinct episodes of subglacial growth and subsequent dissociation that modulated methane release over millennial timescales.

Significance Methane released from the seafloor and transported to the atmosphere has the potential to amplify global warming. At an arctic site characterized by high methane flux from the seafloor, we measured methane and carbon dioxide (CO 2 ) exchange across the sea−air interface. We found that CO 2 uptake in an area of elevated methane efflux w...

SI Serov et al. www.pnas.org/cgi/content/short/1619288114

While the Arctic is warming at a rate of almost twice the global average and needs particular attention for climate impacts, it is a challenging place to perform oceanic measurement, especially in regions of seasonal sea ice cover and stormy seasons. The Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) aims at understanding the impact...

We find that summer methane (CH4) release from seabed sediments west of Svalbard substantially increases CH4 concentrations in the ocean but has limited influence on the atmospheric CH4 levels. Our conclusion stems from complementary measurements at the seafloor, in the ocean, and in the atmosphere from land-based, ship and aircraft platforms durin...

The Arctic Ocean is one of the fastest changing oceans, plays an important role in global carbon cycling, and yet is a particularly challenging ocean to study, hence observations tend to be relatively sparse in both space and time. How the Arctic functions, geophysically, but also ecologically, can have significant consequences for the internal cyc...

A large scale multidisciplinary mesocosm experiment in an Arctic fjord (Kongsfjorden, Svalbard; 78° 56.2´ N) was used to study Arctic marine food webs and biogeochemical elements cycling at natural and elevated future carbon dioxide (CO2) levels. At the start of the experiment marine-derived chromophoric dissolved organic matter (CDOM) dominated th...

Studying more than 3600 observations of particulate organic carbon (POC) and particulate organic nitrogen (PON), we evaluate the applicability of the classic Redfield C:N ratio (6.6) and the recently proposed Sterner ratio (8.3) for the Arctic Ocean and pan-Arctic shelves. The confidence intervals for C:N ranged from 6.43 to 8.82, while the average...

Net community production (NCP) and carbon to nutrient uptake ratios were studied during a large-scale mesocosm experiment on ocean acidification in Kongsfjorden, western Svalbard, during June–July 2010. Nutrient depleted fjord water with natural plankton assemblages, enclosed in nine mesocosms of �50m3 in volume, was exposed to pCO2 levels ranging...

Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental budg...

The effect of ocean acidification on the balance between gross community production (GCP) and community respiration (CR) (i.e. net community production, NCP) of plankton communities was investigated in summer 2010 in Kongsfjorden, West of Svalbard. Surface water, which was characterized by low concentrations of dissolved inorganic nutrients and chl...

Ocean acidification and carbonation, driven by anthropogenic emissions of carbon dioxide (CO2), have been shown to affect a variety of marine organisms and are likely to change ecosystem functioning. High latitudes, especially the Arctic, will be the first to encounter profound changes in carbonate chemistry speciation at a large scale, namely the...

Ocean acidification and carbonation, driven by anthropogenic emissions of carbon dioxide (CO2), have been shown to affect a variety of marine organisms and are likely to change ecosystem functioning. High latitudes, especially the Arctic, will be the first to encounter profound changes in carbonate chemistry speciation at a large scale, namely the...

A major, potential stressor of marine systems is the changing water chemistry following increasing seawater carbon dioxide concentration (CO2), commonly termed ocean acidification. In order to understand how an Arctic pelagic ecosystem may respond to future CO2, a deliberate ocean acidification and nutrient perturbation study was undertaken in an A...

Net community production (NCP) and ratios of carbon to nutrient consumption were studied during a large-scale mesocosm experiment on ocean acidification in Kongsfjorden, West Spitsbergen, during June-July 2010. Nutrient-deplete fjord water with natural phyto- and bacteriaplankton assemblages, enclosed in nine mesocosms of ~ 50 m3 volume, was expose...

Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining the temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental...

Ocean acidification may stimulate primary production through increased availability of inorganic carbon in the photic zone, which may in turn change the biogenic flux of dissolved organic carbon (DOC) and the growth potential of heterotrophic bacteria. To investigate the effects of ocean acidification on marine bacterial assemblages, a two-by-three...

Ocean acidification may stimulate primary production through increased availability of inorganic carbon in the photic zone, which may in turn change the biogenic flux of dissolved organic carbon (DOC) and the growth potential of heterotrophic bacteria. To investigate the effects of ocean acidification on marine bacterial assemblages, a two-by-three...