News

Microbial oxidation as a methane sink beneath the West Antarctic Ice Sheet

Anstract.

"Aquatic habitats beneath ice masses contain active microbial ecosystems capable of cycling important greenhouse gases, such as methane (CH4). A large methane reservoir is thought to exist beneath the West Antarctic Ice Sheet, but its quantity, source and ultimate fate are poorly understood. For instance, O2 supplied by basal melting should result in conditions favourable for aerobic methane oxidation. Here we use measurements of methane concentrations and stable isotope compositions along with genomic analyses to assess the sources and cycling of methane in Subglacial Lake Whillans (SLW) in West Antarctica. [...]"

Source: Nature Geoscience
Authors: Alexander B. Michaud et al.
DOI: 10.1038/ngeo2992

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Influence of seaway changes during the Pliocene on tropical Pacific climate in the Kiel climate model

 Mean state, annual cycle, ENSO, and their interactions

Abstract.

"The El Niño/Southern Oscillation (ENSO) is the leading mode of tropical Pacific interannual variability in the present-day climate. Available proxy evidence suggests that ENSO also existed during past climates, for example during the Pliocene extending from about 5.3 million to about 2.6 million years BP. Here we investigate the influences of the Panama Seaway closing and Indonesian Passages narrowing, and also of atmospheric carbon dioxide (CO2) on the tropical Pacific mean climate and annual cycle, and their combined impact on ENSO during the Pliocene. [...]"

Source: Climate Dynamics
Authors: Zhaoyang Song, Mojib Latif, Wonsun Park, Uta Krebs-Kanzow, Birgit Schneider
DOI: 10.1007/s00382-016-3298-x

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Deep-ocean dissolved organic matter reactivity along the Mediterranean Sea: does size matter?

Abstract.

"Despite of the major role ascribed to marine dissolved organic matter (DOM) in the global carbon cycle, the reactivity of this pool in the dark ocean is still poorly understood. Present hypotheses, posed within the size-reactivity continuum (SRC) and the microbial carbon pump (MCP) conceptual frameworks, need further empirical support. Here, we provide field evidence of the soundness of the SRC model. We sampled the high salinity core-of-flow of the Levantine Intermediate Water along its westward route through the entire Mediterranean Sea. At selected sites, DOM was size-fractionated in apparent high (aHMW) and low (aLMW) molecular weight fractions using an efficient ultrafiltration cell. [...]"

Source: Scientific Reports
Authors: Alba María Martínez-Pérez, Xosé Antón Álvarez-Salgado, Javier Arístegui & Mar Nieto-Cid
DOI: 10.1038/s41598-017-05941-6

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Persistent spatial structuring of coastal ocean acidification in the California Current System

Abstract.

"The near-term progression of ocean acidification (OA) is projected to bring about sharp changes in the chemistry of coastal upwelling ecosystems. The distribution of OA exposure across these early-impact systems, however, is highly uncertain and limits our understanding of whether and how spatial management actions can be deployed to ameliorate future impacts. Through a novel coastal OA observing network, we have uncovered a remarkably persistent spatial mosaic in the penetration of acidified waters into ecologically-important nearshore habitats across 1,000 km of the California Current Large Marine Ecosystem.  [...]"

Source: Scientific Reports
Authors: F. Chan et al.
DOI: 10.1038/s41598-017-02777-y

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The geologic history of seawater pH

Abstract.  

"Although pH is a fundamental property of Earth’s oceans, critical to our understanding of seawater biogeochemistry, its long-timescale geologic history is poorly constrained. We constrain seawater pH through time by accounting for the cycles of the major components of seawater. We infer an increase from early Archean pH values between ~6.5 and 7.0 and Phanerozoic values between ~7.5 and 9.0, which was caused by a gradual decrease in atmospheric pCO2 in response to solar brightening, alongside a decrease in hydrothermal exchange between seawater and the ocean crust. [...]"

Source: Science Vol. 355
Authors: I. Halevy, A. Bachan
DOI: 10.1126/science.aal4151

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A significant net sink for CO2 in Tokyo Bay

Abstract.

"Most estuaries and inland waters are significant source for atmospheric CO2 because of input of terrestrial inorganic carbon and mineralization of terrestrially supplied organic carbon. In contrast to most coastal waters, some estuaries with small freshwater discharge are weak source or sometimes sink for CO2. Extensive surveys of pCO2 in Tokyo Bay showed that the overall bay acts as a strong net sink for atmospheric CO2. Although small area was a consistent source for CO2, active photosynthesis driven by nutrient loading from the land overwhelmed the CO2 budget in the bay. [...]"

Source: Scientific Reports Vol. 7
Authors: Atsushi Kubo, Yosaku Maeda & Jota Kanda
DOI: 10.1038/srep44355

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