![]() ![]() Therefore, as sea ice grows, more salt is expelled into the oceans, increasing the amount available to form dense, saline AABW.įour Antarctic regions showing the transport of surface water to depth (red colour scale), as well as the flow of tracer dyes (green colour scale) away from them, indicating AABW currents. This creates polynyas, which are exposed to the full force of cold Antarctic air, thus encouraging sea ice formation at a much faster rate. The former scenario was found to have strong impacts on ocean circulation for up to a decade thereafter, while the latter results from the narrower East Antarctic shelf causing rapid export of Deep Sea Water (DSW) that prevents accumulation at depth.Ī posited cause of this increased AABW formation from the Weddell and Ross Seas is weaker polar easterly winds, or even complete reversal to westerlies, which reduce the amount of sea ice being transported into the area, therefore leaving more open ocean. 2023ĪABW reservoir export from the Weddell and Ross Seas can last up to two years, while for Prydz Bay and the Adélie Coast it is less than a year. Map of the four regions of Antarctica featured in this study, with darker colours indicating peak areas of surface water being transported to depth. These models, reported in the Journal of Geophysical Research: Oceans, consider how changes in sea ice transport, melting of land-based ice and coastal winds impact AABW. Researchers at the University of New South Wales, Australia, simulated the formation and migration of AABW over a 60-year period from four regions around Antarctica (the Weddell and Ross Seas, Prydz Bay and the Adélie Coast) based upon ocean-sea ice models. This salt concentrates in the ocean, making the sea water denser so that it sinks, drawing warmer and more buoyant offshore sea water to the area in a continuous cycle known as thermohaline circulation. It also affects the global climate and sea level rise, which impacts coastal communities.ĪABW forms as a consequence of cold polar winds bringing sea ice into the region, the formation of which expels salt into the ocean (sea ice has a salinity of approximately 5‰, compared to 34.5‰ of the surrounding sea water). This has consequences for ocean temperatures, ventilation and nutrient distribution to the surface, affecting marine ecosystems and the diverse organisms they support. This new idea redefines our search for salt and methane deposits yet it requires further research and consideration, along with the new approach of salt diapir formation in specific salt basins.However, in recent decades AABW has become warmer, less saline and has declined in volume. Following overburden by deposited basin sediments, this viscous, gas-saturated brine can be an engine for diapir formation, which is prior to the crystalline phase. Hence we presume that non-crystalized, over-pressured, salty brine is the appropriate material to trap and host methane. These phenomena generate a surface on which seawater of normal salinity meets the underneath brine of high salinity, and there is no diffusion between them. ![]() Hereby we describe a new mechanism for DHAB generation due to membrane polarization. It highlights the need to reconsider the classical approach to salt and methane generation due to new observations. Since salt basins overlap some of the most productive gas provinces, this article aims to introduce a new approach to salt and methane generation. The extreme life conditions of the bacteria and the facieses, as found in currently existing supersaturated salt brines DHABs, may have also existed in the geological past. This premise allows us to hypothesize that some methane accumulations in geological reservoirs may have been generated by historical euryhaline bacteria. ![]() We suppose that there is analogy between the recent and ancient DHABs. The existence of deep marine hypersaline anoxic basins (DHAB) has been well-documented starting with the MedRiff Project in the Eastern Mediterranean. ![]()
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