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Categories: Geoscience: Oceanography, Offbeat: Space
Published Mercury levels in tuna remain nearly unchanged since 1971
(via sciencedaily.com) Original source Tuna is one of the most popular seafoods worldwide. But this protein-rich fish can build up high levels of methylmercury from feeding on contaminated prey, like smaller fish or crustaceans. Despite efforts to reduce mercury emissions into the environment, researchers report that levels in tuna appear to be unchanged since 1971. They warn that more aggressive emission reduction targets are needed to start nudging down tuna mercury levels.
Published Black hole at center of the Milky Way resembles a football
(via sciencedaily.com) Original source The supermassive black hole in the center of the Milky Way is spinning so quickly it is warping the spacetime surrounding it into a shape that can look like a football, according to a new study. That football shape suggests the black hole is spinning at a substantial speed, which researchers estimated to be about 60% of its potential limit.
Published Gulf corals still suffering more than a decade after Deepwater Horizon oil spill, scientists report
(via sciencedaily.com) Original source Deep-water corals in the Gulf of Mexico are still struggling to recover from the devastating Deepwater Horizon oil spill in 2010, scientists report at the Ocean Science Meeting in New Orleans. Comparing images of more than 300 corals over 13 years -- the longest time series of deep-sea corals to date -- reveals that in some areas, coral health continues to decline to this day.
Published Decline in microbial genetic richness in the western Arctic Ocean
(via sciencedaily.com) Original source Researchers analyzed archival samples of bacteria and archaea populations taken from the Beaufort Sea, bordering northwest Canada and Alaska. The samples were collected between 2004 and 2012, a period that included two years -- 2007 and 2012 -- in which the sea ice coverage was historically low. The researchers looked at samples taken from three levels of water: the summer mixed layer, the upper Arctic water below it and the Pacific-origin water at the deepest level. The study examined the microbes' genetic composition using bioinformatics and statistical analysis across the nine-year time span. Using this data, the researchers were able to see how changing environmental conditions were influencing the organisms' structure and function.
Published Astronomers report oscillation of our giant, gaseous neighbor
(via sciencedaily.com) Original source A few years ago, astronomers uncovered one of the Milky Way's greatest secrets: an enormous, wave-shaped chain of gaseous clouds in our sun's backyard, giving birth to clusters of stars along the spiral arm of the galaxy we call home. Naming this astonishing new structure the Radcliffe Wave, the team now reports that the Radcliffe Wave not only looks like a wave, but also moves like one -- oscillating through space-time much like 'the wave' moving through a stadium full of fans.
Published Viruses that can help 'dial up' carbon capture in the sea
(via sciencedaily.com) Original source Armed with a catalog of hundreds of thousands of DNA and RNA virus species in the world's oceans, scientists are now zeroing in on the viruses most likely to combat climate change by helping trap carbon dioxide in seawater or, using similar techniques, different viruses that may prevent methane's escape from thawing Arctic soil.
Published Giant Antarctic sea spiders reproductive mystery solved
(via sciencedaily.com) Original source Instead of carrying the babies until they hatched, as in most species of sea spiders, one parent (likely the father) spent two days attaching the eggs to the rocky bottom where they developed for several months before hatching as tiny larvae.
Published Anoxic marine basins are among the best candidates for deep-sea carbon sequestration
(via sciencedaily.com) Original source Anoxic marine basins may be among the most viable places to conduct large-scale carbon sequestration in the deep ocean, while minimizing negative impacts to marine life. As we explore ways to actively draw down the levels of carbon in the atmosphere, sending plant biomass to these barren, oxygen-free zones on the seafloor becomes an option worth considering.
Published Beyond peak season: Bacteria in the Arctic seabed are active all year round
(via sciencedaily.com) Original source Researchers studied the composition and function of bacteria in the seabed off Svalbard, during alternating periods of polar night and midnight sun. To do this, they specially developed a sampling device, the Ellrott grab. In contrast with bacterial communities in the overlying water, the sediment bacteria hardly change with the seasons. This is probably due to the fact that in the seabed some hard-to-digest foods are available all year round.
Published Searching for clues in the history book of the ocean
(via sciencedaily.com) Original source New research has shown that the tropical subsurface ocean gained oxygen during the Paleocene-Eocene Thermal Maximum (commonly referred to as PETM). During this short-lived interval of time in Earth s history that occurred 56 million years ago the average temperatures rose by up to six degrees within a few thousand years.
Published Evidence of geothermal activity within icy dwarf planets
(via sciencedaily.com) Original source A team found evidence for hydrothermal or metamorphic activity within the icy dwarf planets Eris and Makemake, located in the Kuiper Belt. Methane detected on their surfaces has the tell-tale signs of warm or even hot geochemistry in their rocky cores, which is markedly different than the signature of methane from a comet.
Published Diverse ancient volcanoes on Mars discovered by planetary scientist may hold clues to pre-plate tectonic activity on Earth
(via sciencedaily.com) Original source A geologist has revealed intriguing insights into the volcanic activity on Mars. He proposes that Mars has significantly more diverse volcanism than previously realized, driven by an early form of crust recycling called vertical tectonics. The findings shed light on the ancient crust of Mars and its potential implications for understanding early crustal recycling on both Mars and Earth.
Published A star like a Matryoshka doll: New theory for gravastars
(via sciencedaily.com) Original source If gravitational condensate stars (or gravastars) actually existed, they would look similar to black holes to a distant observer. Two theoretical physicists have now found a new solution to Albert Einstein's theory of general relativity, according to which gravitational stars could be structured like a Russian matryoshka doll, with one gravastar located inside another.
Published Early-stage subduction invasion
(via sciencedaily.com) Original source Our planet's lithosphere is broken into several tectonic plates. Their configuration is ever-shifting, as supercontinents are assembled and broken up, and oceans form, grow, and then start to close in what is known as the Wilson cycle.
Published New 'time travel' study reveals future impact of climate change on coastal marshes
(via sciencedaily.com) Original source A new study offers a glimpse into the possible impact of climate change on coastal wetlands 50 years or longer into the future. Scientists are usually forced to rely on computer models to project the long-term effects of rising seas, but an unexpected set of circumstances enabled a real-world experiment along the Gulf Coast.
Published Frequent marine heatwaves in the Arctic Ocean will be the norm
(via sciencedaily.com) Original source Marine heatwaves will become a regular occurrence in the Arctic in the near future and are a product of higher anthropogenic greenhouse-gas emissions -- as shown in a new study.
Published Researchers studying ocean transform faults, describe a previously unknown part of the geological carbon cycle
(via sciencedaily.com) Original source This study reports widespread mineral carbonation of mantle rocks in an oceanic transform fueled by magmatic degassing of CO2. The findings describe a previously unknown part of the geological carbon cycle in transform faults that represent one of the three principal plate boundaries on Earth. The confluence of tectonically exhumed mantle rocks and CO2-rich alkaline basalt formed through limited extents of melting characteristic of the St. Paul's transform faults may be a pervasive feature at oceanic transform faults in general. Because transform faults have not been accounted for in previous estimates of global geological CO2 fluxes, the mass transfer of magmatic CO2 to the altered oceanic mantle and seawater may be larger than previously thought.
Published When the global climate has the hiccups
(via sciencedaily.com) Original source Climate changes usually happens over long periods of time, but during the last glacial period, extreme fluctuations in temperature occurred within just a few years. Researchers have now been able to prove the phenomenon also occurred during the penultimate glacial period.
Published Mysterious gap in size distribution of super-earths explained
(via sciencedaily.com) Original source Astronomers have uncovered evidence of how the enigmatic gap in the size distribution of exoplanets at around two Earth radii emerges. Their computer simulations demonstrate that the migration of icy, so-called sub-Neptunes into the inner regions of their planetary systems could account for this phenomenon. As they draw closer to the central star, evaporating water ice forms an atmosphere that makes the planets appear larger than in their frozen state. Simultaneously, smaller rocky planets gradually lose a portion of their original gaseous envelope, causing their measured radius to shrink over time.
Published Ice cores provide first documentation of rapid Antarctic ice loss in the past
(via sciencedaily.com) Original source Researchers have uncovered the first direct evidence that the West Antarctic Ice Sheet shrunk suddenly and dramatically at the end of the Last Ice Age, around eight thousand years ago. The evidence, contained within an ice core, shows that in one location the ice sheet thinned by 450 meters -- that's more than the height of the Empire State Building -- in just under 200 years.