{"id":11083,"date":"2017-01-01T07:04:24","date_gmt":"2017-01-01T07:04:24","guid":{"rendered":"http:\/\/revoscience.com\/en\/?p=11083"},"modified":"2017-01-01T07:04:24","modified_gmt":"2017-01-01T07:04:24","slug":"fossil-fuel-formation-key-atmospheres-oxygen","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/fossil-fuel-formation-key-atmospheres-oxygen\/","title":{"rendered":"Fossil fuel formation: Key to atmosphere\u2019s oxygen?"},"content":{"rendered":"

\"\"For the development of animals, nothing \u2014 with the exception of DNA \u2014 may be more important than oxygen in the atmosphere.<\/span><\/p>\n

Oxygen enables the chemical reactions that animals use to get energy from stored carbohydrates \u2014 from food. So it may be no coincidence that animals appeared and evolved during the \u201cCambrian explosion,\u201d which coincided with a spike in atmospheric oxygen roughly 500 million years ago.<\/span><\/p>\n

It was during the Cambrian explosion that most of the current animal designs appeared.<\/span><\/p>\n

In green plants, photosynthesis separates carbon dioxide into molecular oxygen (which is released to the atmosphere), and carbon (which is stored in carbohydrates).<\/span><\/p>\n

But photosynthesis had already been around for at least 2.5 billion years. So what accounted for the sudden spike in oxygen during the Cambrian?<\/span><\/p>\n

\"\"
This black shale, formed 450 million years ago, contains fossils of trilobites and other organic material that helped support increases in oxygen in the atmosphere.<\/figcaption><\/figure>\n

A study now online in the February issue of Earth and Planetary Science Letters links the rise in oxygen to a rapid increase in the burial of sediment containing large amounts of carbon-rich organic matter. The key, says study co-author Shanan Peters<\/a>, a professor of geoscience at the University of Wisconsin\u2013Madison, is to recognize that sediment storage blocks the oxidation of carbon.<\/span><\/p>\n

Without burial, this oxidation reaction causes dead plant material on Earth\u2019s surface to burn. That causes the carbon it contains, which originated in the atmosphere, to bond with oxygen to form carbon dioxide. And for oxygen to build up in our atmosphere, plant organic matter must be protected from oxidation.<\/span><\/p>\n

And that\u2019s exactly what happens when organic matter \u2014 the raw material of coal, oil and natural gas \u2014 is buried through geologic processes.<\/span><\/p>\n

To make this case, Peters and his postdoctoral fellow Jon Husson<\/a> mined a unique data set called Macrostrat<\/a>, an accumulation of geologic information on North America whose construction Peters has masterminded for 10 years.<\/span><\/p>\n

The parallel graphs of oxygen in the atmosphere and sediment burial, based on the formation of sedimentary rock, indicate a relationship between oxygen and sediment. Both graphs show a smaller peak at 2.3 billion years ago and a larger one about 500 million years ago.<\/span><\/p>\n

\u201cIt\u2019s a correlation, but our argument is that there are mechanistic connections between geology and the history of atmospheric oxygen,\u201d Husson says. \u201cWhen you store sediment, it contains organic matter that was formed by photosynthesis, which converted carbon dioxide into biomass and released oxygen into the atmosphere. Burial removes the carbon from Earth\u2019s surface, preventing it from bonding molecular oxygen pulled from the atmosphere.\u201d<\/span><\/p>\n

\"\"
Shanan Peters<\/figcaption><\/figure>\n

Some of the surges in sediment burial that Husson and Peters identified coincided with the formation of vast fields of fossil fuel that are still mined today, including the oil-rich Permian Basin in Texas and the Pennsylvania coal fields of Appalachia.<\/span><\/p>\n

\u201cBurying the sediments that became fossil fuels was the key to advanced animal life on Earth,\u201d Peters says, noting that multicellular life is largely a creation of the Cambrian.<\/span><\/p>\n

Today, burning billions of tons of stored carbon in fossil fuels is removing large amounts of oxygen from the atmosphere, reversing the pattern that drove the rise in oxygen. And so the oxygen level in the atmosphere falls as the concentration of carbon dioxide rises.<\/span><\/p>\n

The data about North America in Macrostrat reflects the work of thousands of geoscientists over more than a century. The current study only concerns North America, since comprehensive databases concerning the other 80 percent of Earth\u2019s continental surface do not yet exist.<\/span><\/p>\n

The ultimate geological cause for the accelerated sediment storage that promoted the two surges in oxygen remains murky. \u201cThere are many ideas to explain the different phases of oxygen concentration,\u201d Husson concedes. \u201cWe suspect that deep-rooted changes in the movement of tectonic plates or conduction of heat or circulation in the mantle may be in play, but we don\u2019t have an explanation at this point.\u201d<\/span><\/p>\n

Holding a chunk of trilobite-studded Ordovician shale that formed approximately 450 million years ago, Peters asks, \u201cWhy is there oxygen in the atmosphere? The high school explanation is \u2018photosynthesis.\u2019 But we\u2019ve known for a long time, going all the way back to Wisconsin geologist (and University of Wisconsin president) Thomas Chrowder Chamberlin, that building up oxygen requires the formation of rocks like this black shale, which can be rich enough in carbon to actually burn. The organic carbon in this shale was fixed from the atmosphere by photosynthesis, and its burial and preservation in this rock liberated molecular oxygen.\u201d<\/span><\/p>\n

What\u2019s new in the current study, Husson says, is the ability to document this relationship in a broad database that covers 20 percent of Earth\u2019s land surface.<\/span><\/p>\n

Continual burial of carbon is needed to keep the atmosphere pumped up with oxygen. Many pathways on Earth\u2019s surface, Husson notes, like oxidation of iron \u2014 rust \u2014 consume free oxygen. \u201cThe secret to having oxygen in the atmosphere is to remove a tiny portion of the present biomass and sequester it in sedimentary deposits. That\u2019s what happened when fossil fuels were deposited.\u201d<\/span><\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

For the development of animals, nothing \u2014 with the exception of DNA \u2014 may be more important than oxygen in the atmosphere. Oxygen enables the chemical reactions that animals use to get energy from stored carbohydrates \u2014 from food. So it may be no coincidence that animals appeared and evolved during the \u201cCambrian explosion,\u201d which […]<\/p>\n","protected":false},"author":6,"featured_media":11085,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16,17],"tags":[],"class_list":["post-11083","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-biology","category-research"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",775,581,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581-300x225.jpg",300,225,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581-768x576.jpg",750,563,true],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",750,562,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",775,581,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",775,581,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",775,581,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",760,570,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",600,450,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",600,450,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",654,490,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",480,360,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",87,65,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",640,480,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",96,72,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/01\/nova-scotia-1-JH_LK-775x581.jpg",150,112,false]},"author_info":{"info":["Amrita Tuladhar"]},"category_info":"Biology<\/a> Research<\/a>","tag_info":"Research","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/11083","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=11083"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/11083\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/11085"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=11083"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=11083"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=11083"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}