Thursday, November 20, 2014

It's winter! Marine snow?

Six feet in 24 hours: that was the unfortunate high rate of snowfall in Buffalo, New York, on the shore of Lake Erie on Tuesday, 11/18/2014. Even for a region used to very snowy winters, that was excessive and paralyzing.

Six meters in a million years. That is the accumulation rate for "marine snow". Marine snow, according to the National Oceanic and Atmospheric Administration (NOAA) informational webpage on the subject (http://oceanservice.noaa.gov/facts/marinesnow.html), is the shower of organic matter falling from upper marine waters to the ocean bottom. The "snow" consists of fluffy agglomerations of generally structureless decaying organic matter, the microbes feasting on it, clay particles, dust, tiny plankton shell pieces. The "flakes" may get to several centimeters. The organic matter may be consumed or depleted before it settles on the bottom, or may accumulate and be a food source at the seafloor. The NOAA page says that 3/4 of the seafloor may be covered with an accumulated organic ooze from marine snow deposition.
One-centimeter aquatic snow aggregate, Lake Constance, Germany.
Microbes consume organic matter in marine snow and release carbon dioxide, so the velocity of settling affects exposure time and has a direct impact on the amount of CO2 released back to the ocean. The amount and type of particulates in the snow affect the density of a clump and its settling rate. In Proceedings of the National Academy of Sciences in 2010, Kindler and others (http://www.sciencedaily.com/releases/2010/12/101208125759.htm) conclude that the highly porous marine snow (~95% water) may stall during their journey to the bottom when increasing water density halts settling. When diffusion eventually replaces the less dense water from shallower depths within the flakes with denser water, the agglomerations resume their journey to the bottom.
Besides its importance in the ocean carbon cycle, the amorphous organic matter (AOM) in marine snow is a great petroleum precursor. If preserved, due to low or zero oxygen in ocean floor sediments or overlying waters, and buried to a few km or more, the AOM will start producing liquid hydrocarbons. A good description of amorphous organic matter and various formation pathways, modern and ancient, is found in the 1995 text "Sedimentary Organic Matter" by R. V. Tyson. Pacton and others (2011; http://www.climategeology.ethz.ch/publications/2011a_Pacton_et_al.pdf) describe the structures and process of formation of amorphous organic matter at the sediment/water interface.

Tuesday, November 11, 2014

Veterans Day and carbon helping those who served

Today in the United States is Veterans' Day, a federal holiday honoring all Americans who have served in the military. Originally, this day was called Armistice Day, commemorating the end, by treaty, of hostilities on 11/11/1918 at 11:00 a.m. (in western Europe) in World War I, "the war to end all wars". However, after World War II, the day was expanded and renamed to honor all who have served in the armed forces. My grandfather served in Europe in WWI: he had been in the cavalry previously, riding a horse in the Mexican Expedition against Pancho Villa in 1916, but by the time of US involvement in WWI, his unit did not use horses, but tanks, as the "cavalry" still does today.

Googling his name online, I found my grandfather was reported to have been "wounded, degree undetermined" in September 1918. I never remember hearing about or noticing this injury, so it obviously must not have been debilitating. Hundreds of veterans of all wars, however, do live with permanent physical and mental disabilities. There is a new monument opened recently in Washington, DC, at the southwest foot of Capitol Hill, American Veterans Disabled for Life Memorial, that honors the sacrifice of military members severely wounded.
Looking to the south, across star-shaped and rectangular reflecting infinity pools to Voices of Veterans walls.

To the north towards the Botanic Gardens and US Capitol.


The bottom quote in the above portion of the Voices of Veterans wall is by Harold Russell, a World War II veteran who lost both his hands in a 1944 training accident. He is most famous for his portrayal of a returning wounded soldier, Homer Parrish, in "The Best Years of Our Lives" which won Best Picture at the 1947 Academy Awards. Russell won two Oscars: Best Supporting Actor and an honorary award for "bringing hope and courage to fellow veterans". I have seen the movie through at least once, but my favorite part, that I have seen several times, is at the end, when Homer, who has emotionally pushed away his fiancée since his return, accepts her love and commitment after she insists on helping him remove his prostheses getting ready for bed (http://www.youtube.com/watch?v=t-VB9JnppAU).

In the movie, Russell's prostheses appear to be primarily metal with leather. Charlie McGonegal, quoted above Russell on the Voices of Veterans wall, lost both arms in WWI and is featured in a 1944 War Department film, "Meet McGonegal", made to show how a double amputee can successfully manage every-day tasks. From watching the film, McGonegal's prostheses may include plastic.(McGonegal visited and worked with Russell during his recovery period, described in the book, Enabling Lives, 1999.)

A 2012 article from Collector's Weekly ("War and Prothetics: How Veterans Fought for the Perfect Artificial Limb; http://www.collectorsweekly.com/articles/war-and-prosthetics/) describes the history of prosthetic development and how, regrettably, war injuries have driven advancements in this technology, even though there are more US amputees due to diabetes. According to the article, plastics were first used by the Germans, after WWI, in prosthetic manufacture. Among the more space-age materials now used are carbon-fiber composites which have carbon fibers for reinforcement and a polymer matrix binder. Carbon fibers are manufactured primarily from petroleum-refinery byproducts or, rarely, directly from petroleum pitch or coal tar. These carbon materials provide strength and flexibility and are relatively lightweight. Carbon composites have myriad automotive and aerospace applications and are popular materials in sports equipment. An internet search reveals that prosthetic feet seem to be the most common artificial limbs using carbon composites. Of course, an important carbon fiber in military applications is Kevlar, used in body armor to protect from injury those that volunteer to defend their countries in the armed forces.

Wednesday, November 5, 2014

"Deep Carbon Through Deep Time" short course, GSA 2014


On Saturday, October 18, during the 2014 Geological Society of America annual meeting in Vancouver, I attended the short course “Deep Carbon Through Deep Time” sponsored by the Deep Carbon Observatory (DCO, ten-year interdisciplinary international project administered out of the Geophysical Laboratory, Carnegie Institution of Washington [CIW; https://deepcarbon.net/dco/deep-carbon-science]) and the Mineralogical Society of America. Having experience, either long-term or in passing, with a temperature range of carbon-bearing or organic rocks from mushy ocean floor muds through the anchizone to graphitic schists, I was interested in boldly going deeper than I carbonaceously had gone before.

What is the purpose of the Deep Carbon Observatory initiative? To quote from the short course description, “Yet in spite of carbon’s importance to geology, many aspects of the physical, chemical, and biological behavior of Earth’s subsurface carbon-bearing systems remain unresolved. . . How do deep reservoirs form and evolve? How does carbon move from one deep repository to another?”

Since most of us, when we think of the carbon cycle, usually consider the relatively-shallow upper crust, and Phanerozoic oceans and atmosphere, this short course could have been called “Deeper Carbon Through Deeper Time” because that is where it took me. As Robert Hazen, DCO Executive Director, and Craig Schiffries, DCO Director and former GSA Director for Geoscience Policy, wrote in the first chapter, "Why Deep Carbon?" in Carbon in Earth (2013, Reviews in Mineralogy and Geochemistry, Volume 75; http://www.minsocam.org/MSA/RIM/RiMG075/RiMG075_Ch01.pdf), possibly 90% of the earth's carbon may be in the Earth's deep interior: if carbonaceous chondrite meteorites, used as a compositional model for early planets, have 10-100 times the concentration of carbon as the earth's known carbon reservoirs, where is our missing carbon? Hazen and Schiffries write that identifying and quantifying carbon fluxes to and from the mantle are key in answering this question.

Seven speakers in the short course covered a range of topics within the four DCO communities (extreme physics and chemistry; reservoirs and fluxes; deep life; deep energy) including deep (mantle/core) carbon cycle, diamonds, volcano outgassing, carbon fluids, deep extremophiles (https://deepcarbon.net/sites/dco.rpi.edu/files/shortcourse-schedule-18oct14.pdf). These talks averaged 45-minutes to an hour each, which for soporific me in a small windowless conference room, could have meant a constant battle to stay awake, but I found the talks so gripping that only a couple times all day did I have to pinch myself.

A common theme among the talks was the history of the carbon itself: where it is now, where it had been, how long it was there: transport, reservoirs, residence time (=cycle time). Radiometric age dating, trace element geochemistry, and staple isotopes are among the techniques used on natural samples obtained through deep drilling or that have been brought within our relatively shallow sampling reach by geologic processes (i.e. diamonds). The magnitude of transit in time and depth for Earth carbon was apparent in Steve Shirey's (CIW) diamond talk in which inclusions captured within those crystals record ancient and profound journeys. While I have familiarity with crustal scale advective heat flow in basin thermal modeling, and some of that research has been associated with deep extremophile studies (how hot was the microbes’ environment), it was fascinating to hear Barbara Sherwood Lollar talk about adjacent (meter-scale), but separate, water sources in deep South African gold mines where one source had relatively young meteoric water and the other, unmixed, was millions of years old, both bearing microbes. Sherwood Lollar has also identified 1.5 billion-year-old fluid (non-microbial-bearing) in fractures in a deep mine in Ontario.

While there was a lot of new information presented, relative to my own background, the major take-away for me was a new or expanded scope of thinking about Earth carbon history and distribution. Perhaps the best example was the first talk by Bob Hazen on Mineral Evolution. From our earliest education as geologists, we are aware that plate tectonics, lithospheric differentiation, oxygen atmosphere, life were not present at planet formation, but evolved over the first few billion years of Earth history. However, I never knew or considered that the number of and variety within minerals has changed also, even though now this seems blatantly logical. Hazen’s talk went beyond the Earth and its infancy to mention where the first mineral formed: diamond condensed from supernova vapor in the early universe. The big stunner for some of us was that there are organic minerals, taking the definition of mineral as anything that creates a diffraction pattern, not the general inorganic vs. organic classifier we are initially taught.

Although the DCO initiative focuses on carbon, this endeavor encompasses essentially all disciplines of the earth sciences. I started to list the involved disciplines that came to mind, but realized I was listing everything under the geoscience umbrella. While participating researchers focus on what their own specialties can add to carbon knowledge, the conversation fostered by the DCO will produce a comprehensive and connected understanding of the Earth carbon system, and expand our individual scientific experience from local to “cosmos”-politan in terms of time, space, and process.

I highly recommend Carbon in Earth, Reviews in Mineralogy and Geochemistry, Volume 75 (2013, 680 pages), the medial publication of the 10-year DCO project. Many of the speakers at the short course are authors of chapters in this volume. It (and its spectacular graphics) is available as an Open Access publication at http://www.minsocam.org/MSA/RIM/Rim75.html