"The Goldschmidt Conferences® were started in 1988 by the international Geochemical Society (GS) to provide a forum for its members to discuss their latest research. The conference is named in honour of Victor M. Goldschmidt (1888 - 1947), whose classification of the behaviour of the elements in the Earth and meteorites laid the basis of modern geochemistry. Each year, the conference brings together thousands of scientists from throughout the world to talk about subjects including the origin of the Earth and planets, the chemical processes that have shaped Earth's evolution over time, the interconnections between life and the physical world, the search for new resources, and the environmental challenges facing today's world."
Read more about the Goldschmidt Conference 2017.
Start Date: 8/12/17
Origin and fate of methane in the Eastern Tropical North Pacific oxygen minimum zone
"Oxygen minimum zones (OMZs) contain the largest pools of oceanic methane but its origin and fate are poorly understood. High-resolution (<15 m) water column profiles revealed a 300 m thick layer of elevated methane (20–105 nm) in the anoxic core of the largest OMZ, the Eastern Tropical North Pacific. Sediment core incubations identified a clear benthic methane source where the OMZ meets the continental shelf, between 350 and 650 m, with the flux reflecting the concentration of methane in the overlying anoxic water. Further incubations characterised a methanogenic potential in the presence of both porewater sulphate and nitrate of up to 88 nmol g−1day−1 in the sediment surface layer. In these methane-producing sediments, the majority (85%) of methyl coenzyme M reductase alpha subunit (mcrA) gene sequences clustered with Methanosarcinaceae ([above] 96% similarity to Methanococcoides sp.), a family capable of performing non-competitive methanogenesis. Incubations with C-CH4 showed potential for both aerobic and anaerobic methane oxidation in the waters within and above the OMZ. Both aerobic and anaerobic methane oxidation is corroborated by the presence of particulate methane monooxygenase (pmoA) gene sequences, related to type I methanotrophs and the lineage of Candidatus Methylomirabilis oxyfera, known to perform nitrite-dependent anaerobic methane oxidation (N-DAMO), respectively."
MSM61: DIVE INTO THE DEEP
"The deep sea is the largest environment on the planet. Most of the deep sea consists of the water column above the seafloor, the pelagic zone. In many parts of the pelagic ocean, no scientific sample or observation has ever been collected. Consequently, knowledge on deep-sea pelagic biodiversity and on the biology and ecology of organisms in this realm remain largely unknown.
During MSM61 we perform deployments with the pelagic in situ observation system or PELAGIOS. This ocean instrument collects high definition video during horizontal transects while being towed on a CTD cable at various depths of interest.[...]"
Widespread loss of ocean oxygen to become noticeable in 2030s
Upwelling intensity modulates nitrous oxide concentrations over the western Indian shelf
"Repeat measurements of dissolved nitrous oxide (N2O) along two transects of the western continental shelf of India in 2012 revealed high concentrations of 45 ± 32 nM (off Kochi) and 73 ± 63 nM (off Mangalore) during the summer monsoon (SM). N2O concentrations increased nonlinearly during the peak of the SM upwelling, when low O2 (<25 µM) conditions prevailed in the water column. Off Kochi, N2O levels fell gradually from the fall intermonsoon (20 ± 8 nM) to the winter monsoon (8.8 ± 2 nM) and remained low (9.2 ± 5.2 nM) through the spring intermonsoon season. The N2O supersaturation off Kochi (574 ± 720%) was presumably due to its high yield during sediment denitrification, whereas the higher N2O supersaturation observed off Mangalore (1046 ± 885%) was due to its production during denitrification in both the anoxic water column and the underlying sediments. Such distinctive biogeochemical behavior between these two shelf segments is at first augmented by the natural origin of intense upwelling at Mangalore relative to Kochi wherein suboxic to anoxic oxygen minimum zone waters spread from offshore to the shelf of Mangalore, over which the runoff and terrestrial nutrients supply acts in unison.[...]"
Deep sea life faces dark future due to warming and food shortage
New study reveals negative impact of climate change, human activity, acidification and deoxygenation on ocean and its creatures
Major impacts of climate change on deep-sea benthic ecosystems
"The deep sea encompasses the largest ecosystems on Earth. Although poorly known, deep seafloor ecosystems provide services that are vitally important to the entire ocean and biosphere. Rising atmospheric greenhouse gases are bringing about significant changes in the environmental properties of the ocean realm in terms of water column oxygenation, temperature, pH and food supply, with concomitant impacts on deep-sea ecosystems. [...]"
First evidence of denitrification vis-à-vis monsoon in the Arabian Sea since Late Miocene
"In the Arabian Sea, South Asian monsoon (SAM)-induced high surface water productivity coupled with poor ventilation of intermediate water results in strong denitrification within the oxygen minimum zone (OMZ). Despite the significance of denitrification in the Arabian Sea, we have no long-term record of its evolution spanning the past several million years. Here, we present the first record of denitrification evolution since Late Miocene (~10.2 Ma) in the Eastern Arabian Sea, where the SAM generates moderate surface water productivity, based on the samples retrieved during the International Ocean Discovery Program (IODP) Expedition 355. [...]"
Fish under threat from ocean oxygen depletion, finds study
Oxygen levels in oceans have fallen 2% in 50 years due to climate change, affecting marine habitat and large fish such as tuna and sharks
Oceans on the edge of anoxia
For the past several hundred million years, oxygen concentrations in Earth's atmosphere have been comparatively high (1, 2). Yet, the oceans seem never to have been far from anoxia (oxygen depletion) and have occasionally suffered major oceanic anoxic events (OAEs), recognized in the rock record through accumulations of dark, organic-rich shales (3). OAEs seem to be promoted by warm climates, and some have been associated with major environmental crises and global-scale disturbances in the carbon cycle. New insights into the causes of OAEs are now emerging (4, 5). Furthermore, ocean oxygen concentrations are declining in the modern ocean (6). A full-scale OAE would take thousands of years to develop, but some of today's processes are reminiscent of those thought to have promoted OAEs in the distant past."