Stories
Slash Boxes
Comments

SoylentNews is people

posted by janrinok on Tuesday February 06, @01:21PM   Printer-friendly

Arthur T Knackerbracket has processed the following story:

Marine anoxia is characterized by the oceans being severely depleted in dissolved oxygen, making them toxic and thus having devastating impacts on the organisms inhabiting them. One such event, known as Oceanic Anoxic Event 2 (OAE2), occurred ~93.5 million years ago across the Cenomanian-Turonian boundary of the Upper Cretaceous and lasted for up to 700,000 years.

During such scenarios, organic matter is buried at an elevated rate, producing distinctive layers of black shale in the geological record, which are depleted in the isotopically-heavier carbon-13, therefore generating a positive carbon isotope excursion of ~6‰ for this study period.

The specific factors triggering OAE2 are still debated, but the most widely supported is volcanism from the Caribbean Large Igneous Province and High Arctic Large Igneous Province, increasing atmospheric carbon dioxide and therefore warming the planet.

Among the plethora of impacts from a warmer planet is increased weathering of land, with fluvial processes transporting this material to the oceans, providing key nutrients to primary producers in the surface ocean. Enhanced primary productivity produces more oxygen, but trophic food chains ultimately use up more of this oxygen in their metabolic processes.

Compounded by decreased solubility of oxygen in warmer oceans, this results in widespread deoxygenation of Earth's marine realm, the focus of new research published in Climates of the Past.

[...] Revealing the significance of the work, Dr. Abraham said, "Our research delves into the ancient oceans' secrets, specifically a period 93.5 million years ago when much of the ocean was devoid of oxygen. By studying natural chemical fingerprints preserved in marine sediments, we uncover how volcanic activities and climate warming in the past led to drastic ocean deoxygenation. Understanding this in deep time is crucial, as they mirror the challenges we face today with the ongoing climate crisis, helping us predict and mitigate future consequences."

Taking samples of organic matter from the drilled cores, the research team isolated compounds of biological origin that are stable over geological time periods of millions of years, known as biomarkers. Dr. Abraham explains that biomarkers are known as "molecular fossils," adding, "Biomarkers are chemical compounds found in sedimentary rocks that originated from living organisms millions of years ago. Think of them as molecular fossils that, unlike bones or shells, are not easily visible to the naked eye. These compounds, once part of living organisms, have remained chemically stable over vast geological timescales.

"We extract them carefully using a series of chemical procedures and a technique known as gas chromatography–mass spectrometry in the lab to isolate these compounds from the drilled sediments and to avoid contamination.

"Analyzing these biomarkers helps us reconstruct past environmental conditions, such as temperature and oxygen levels in the oceans, but linking their presence to specific historical environmental conditions requires meticulous laboratory work and a profound understanding of geochemical processes."

The scientists found that the percentage of total organic carbon content of the samples increased through the study period (3.8 million years), peaking at ~28 weight % at OAE2 from initial levels of 1–17 weight %. This occurred alongside a ~5-8°C increase in sea surface temperature up to ~43°C.

Key biomarkers of 28,30-dinorhopane and lycopane are indicative of this warming and decline in oxygen, forming an oxygen minimum zone in the Cenomanian, similar to those observed in the Black Sea today. This data is coupled with a noticeable reduction in the abundance of benthic foraminifera (bottom ocean-dwelling single-celled microorganisms) in the late Cenomanian, as they were not able to survive in the depleted-oxygen environment.

Such persistent low-oxygen layers increase in number and size with enhanced warming of the oceans, forming a thick zone at depth below a highly productive thin surface layer that is oxygen-rich. Biomarkers of C35 hopanoid thiophene and isorenieratane reveal this water-column euxinia (both anoxic and sulphidic) expanded to finally reach the surface photic zone through the Cenomanian-Turonian boundary at OAE2.

[...] Looking ahead to the future of Earth's oceans with the expansion of oxygen minimum zones, Dr. Abraham says, "In today's world, oceanic conditions are generally hypoxic but have not yet reached anoxic levels in open oceans. However, closed basins or seas are more prone to becoming anoxic.

"With ongoing global warming, it is predicted that oxygen minimum zones will expand both horizontally and vertically. Warmer water holds less oxygen, and increased surface temperatures can lead to stronger stratification of ocean layers, thereby reducing the mixing that normally replenishes oxygen in deeper waters.

"Additionally, global warming can enhance biological activity in surface waters, resulting in more organic matter sinking to the depths, where it consumes oxygen as it decomposes, a process evident during OAE2.

"Today, oxygen minimum zones are primarily found in the Pacific and Indian Oceans, with conditions making life hard for many marine species. With the current trends of global warming, these zones are expected to expand, reducing habitable marine space and adversely affecting marine biodiversity and fisheries.

"By the end of this century, if the current trajectory of warming and nutrient runoff continues, we might see a significant increase in anoxic and euxinic conditions in our oceans, threatening marine ecosystems and the services they provide to humanity."

Journal information: Climate of the Past


Original Submission

 
This discussion was created by janrinok (52) for logged-in users only, but now has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 2) by JoeMerchant on Tuesday February 06, @11:16PM (1 child)

    by JoeMerchant (3937) on Tuesday February 06, @11:16PM (#1343409)

    The electric (or gas, for that matter) clothes dryer is the ultimate: "F if I care about the environment" appliance. 30A @ 220V it's equivalent to burning 66 100W incandescent bulbs the whole time it's heating - which is much of the time it's running. Liquid-vapor phase transition of water takes a LOT of energy. It's the same reason that vapor barriers are so important for air conditioned spaces - even if the ground isn't warm, if you're getting moisture up from the ground into your air conditioned space, first you're having to condense the water vapor out of the air (very energy intensive) before you can start to cool the air effectively. At least air conditioners are relatively efficient heat pumps, as compared with your clothes dryer which just converts electricity to heat 1:1, and then blows the heat and moist air (and lots of cotton fluff from your clothes, towels and sheets) out a vent - sucking your air-conditioned air with it.

    My first home I lived with two clothes lines, one in the backyard for "express drying" when it was sunny, and another in the un-airconditioned garage where the clothes would dry more slowly and less stiffly. When wife #1 came around there was a demand for a "modern" dryer and so I installed that 10gauge 30A 220V circuit to the garage and then for $325 we got an appliance that would consume another $160 a year in electricity at 0.11/kWh. Wife #1 didn't last long, some years later wife #2 to-be was home doing home-maker things, washing clothes (running the hot water heater), running the 12000BTU A/C unit, the 30A dryer, and probably 600W of "Torcherie" lamps and she called me at work to report "a funny burning smell between the kitchen and the dining room" - "oh, try opening that grey door on the wall - it's not hot is it?" - "no, it's not hot, but that's definitely where the burning smell is coming from" - "O.K., inside there you see the big black thing labeled MAIN?" - "yes" - "pull that, and call your electrician friend." - "But now all the power is off!" - "Yes, but hopefully the house isn't catching fire..." Turns out that the previous owner had installed a 100A circuit breaker panel behind a 60A rated meter can. Gee, thanks for pointing that out Mr. home inspector - NOT. Next house we bought had a 200A panel behind a 125A meter can, that inspector missed that one too. We were going to replace it before having another burning smell, but ended up moving much sooner than planned, the buyer's inspector also did not notice the problem with the 200A panel being fed from a 125A rated meter can.

    >Shave too, gotta shave.

    I gave up professional hair cutting as of November 2019, don't miss it at all. With work-from-home my "Witcher" look works perfectly well. I do trim my own beard once a month or so, and Wife #2 (keeper) has trimmed my hair twice now, since November 2019.

    >there are findings that showering every day is bad for us, but we still do it.

    Again, work from home is changing things... From about 6th grade until 2019, I probably showered and washed my hair an average of 350 times a year - pretty much every morning, skipping the occasional weekend day if I was staying clean and feeling lazy. Since 2020 I'm averaging somewhere under 100 per year - I still tend to feel like I 'need' one after 4-5 days. Work from home also shifted shower time from first thing in the morning to some time between morning meetings and lunch - it's a lot less zombie-like experience.

    >even crazier, the neighbors want you to maintain a monoculture.

    Yeah, f-that. And F-HOAs. I'm much happier with neighbors with illegal burn piles in their yards, pitbulls running loose, and green swimming pools than I ever was in the HOA.

    >much decrying of the inherent waste in throwing out repairable items

    And yet, things continue to get worse on that front.

    >There's the waste in continuing to use printing

    I spent 6 hours across three days online, on the phone, and otherwise attempting to use our county's new electronic building permitting system, getting basically nowhere. So, today I drove downtown, parked, walked 2 miles between the various required offices, stood at 8 different desks (one of them twice) answering questions about my paper printouts and amending them to meet the various bureaucrats' requirements. 4 hours later my permit application is now filed and for the next 30 working days I can (hopefully) track its progress, and lack thereof, from online. Those 8 desks all have their various stamps and signatures and fees that they put on the process, and without those stamps on paper your application goes nowhere. If you haven't seen "Jupiter Ascending" it's worth the time - including the bureaucratic process they depict... I only had to pay off two offices today, but there's a bigger bill coming after (if) they approve everything. Of course, I had to contract with my supplier and pay them 17% down + $300 to get the drawings necessary to get the permit process rolling...

    >maybe your kid will just be run over by a reckless driver.

    Story from our post office counter man... he had a 15 year old son who slipped out his bedroom window one Friday night, first time ever as far as he knows, and died: 80mph into a tree with his friends all in one car less than 5 minutes later. There are probably 100 or more of those kind of stories for every actual pedophile kidnapping, but they don't pump up the news ratings the way that sex trafficking rings do.

    --
    🌻🌻 [google.com]
    Starting Score:    1  point
    Karma-Bonus Modifier   +1  

    Total Score:   2  
  • (Score: 0) by Anonymous Coward on Wednesday February 07, @02:36AM

    by Anonymous Coward on Wednesday February 07, @02:36AM (#1343443)

    > I gave up professional hair cutting as of November 2019

    You're a little late, but welcome to the party! I objected so much to barbers as a lad that my mum mostly cut my hair starting at age ~5, about 1960 -- using a clipper with clip-on-combs (making the standard brush cut of that era). Once I got to high school and then college I let it grow and since then it's been shoulder length (+/-). I scissor off an inch or so every 6 weeks.