Posts Tagged ‘black carbon’

Skidaway Institute Arctic carbon research gets additional exposure

January 27, 2016

The Website Environmental Monitor published a good article on some of the work Skidaway Institute scientist Aron Stubbins has been conducting on carbon in black carbon in the Arctic. OLYMPUS DIGITAL CAMERA

http://www.fondriest.com/news/arctic-ocean-biochar-could-increase-with-global-warming.htm

Climate change likely to increase black carbon input to the Arctic Ocean

November 30, 2015

University of Georgia Skidaway Institute of Oceanography scientist Aron Stubbins led a team of researchers to determine the levels of black carbon in Arctic rivers and found that the input of black carbon to the Arctic Ocean is likely to increase with global warming. The results of their study were recently published in the journal Frontiers in Earth Science.

Black carbon, or biochar, is formed when vegetation and other organic matter burns. Today black carbon is a massive store of carbon in global soils, where it is thought to be very stable — so stable, that researchers have previously suggested that adding black carbon to soils might be a good way to lock away carbon dioxide and reduce climate change. This new research reveals that the black carbon stored in Arctic soils is being exported to the oceans.

Arctic rivers are the major way black carbon is transported to the ocean.

Arctic rivers are the major way black carbon is transported to the ocean.

The Arctic is warming faster than other regions of the planet due to climate change. The scientists report that, as the planet warms, the amount of black carbon transported to the Arctic Ocean will likely increase. Once dissolved in the ocean and exposed to sunlight, black carbon may be rapidly converted back to the greenhouse gas carbon dioxide.

In ongoing work at UGA and partner universities, Stubbins and his colleagues are trying to determine just how much black carbon will be exported to the Arctic Ocean as the Arctic continues to warm, and once it reaches the oceans, what percentage will reach the atmosphere as carbon dioxide.

The article is titled “Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers.” In addition to Stubbins, the co-authors include Robert Spencer from Florida State University; Jutta Niggemann and Thorsten Dittmar from the University of Oldenburg, Germany; Paul Mann from Northumbria University; Max R. Holmes from Woods Hole Research Center; and James McClelland from University of Texas Marine Science Institute.

The entire article can be viewed online at: http://journal.frontiersin.org/article/10.3389/feart.2015.00063/abstract

Stubbins has a website detailing this and other work on black carbon at:

http://www.skio.usg.edu/?p=research/chem/biogeochem/blkcarbon

Study shows rivers a major transport of black carbon to the ocean

April 18, 2013

OLYMPUS DIGITAL CAMERABlack carbon, formed from the burning of biomass and fossil fuels, may account for as much as ten percent of the carbon transported by rivers into the ocean and play a significant role in controlling the balance of two of the most important carbon pools on earth – the soil and the ocean.

This is the finding of a group of scientists, including Aron Stubbins of the Skidaway Institute of Oceanography. This research will appear in the April 19, 2013 issue of the journal Science, published by the AAAS, the science society, the world’s largest general scientific organization. See http://www.sciencemag.org, and also http://www.aaas.org.

Black carbon is organic material that has been altered by heat or combustion, such as the remnants of forest fires or burning fossil fuels. The burning of biomass generates between 40 million and 250 million tons of black carbon every year. Part of that is preserved for thousands of years in soils and sediments where it makes up approximately ten percent of the total carbon there.

Another portion is picked up by drainage and carried by rivers to the ocean. According to Stubbins and his colleagues, as much as ten percent of the carbon dumped by rivers into the ocean may be this black carbon.

This movement of black carbon involves two of the Earth’s three main stores of reactive carbon — in the soil and in the dissolved phase in the ocean. Both are approximately the same size as the third store – the carbon in the atmosphere, in the form of carbon dioxide.

“The balance between those three carbon pools is very important,” said Stubbins. “It controls the levels of carbon dioxide in the atmosphere, which in turn influences local and global climate.”

Black carbon is fairly stable in the marine environment, especially in the deep ocean. However, near the surface black carbon is very photo-sensitive. So when it is exposed to sunlight, it will degrade rapidly.

“In the deep ocean, the degradation is so slow that it would take up to 40 thousand years for the black carbon to be removed,” said Stubbins, “However, stick it in sunlight and 95 percent will disappear in two weeks.”

When exposed to sunlight, the relatively complex black carbon molecules break down into smaller molecules, including carbon dioxide. The CO2 is dissolved in the ocean water where it can be utilized in photosynthesis by microscopic plants called phytoplankton. It can also be released into the atmosphere as part of the constant exchange of gasses between the atmosphere and the water at the ocean surface.

This degradation of black carbon in the surface ocean is apparently happening at a fairly rapid rate. The data in this project suggests that the Earth’s rivers are dumping much more black carbon into the ocean than can be found there.

“So where is it going?” asked Stubbins. “The rivers are dumping ten to 100 times more carbon into the ocean than we are finding there. That means we are losing ten to 99 percent of it.”

Stubbins continued, if that black carbon had remained in the soil, it would have remained stable for thousands of years.

“If you are losing it in the oceans, it is likely being converted into carbon dioxide. This freeing of black carbon from the soils, followed by its conversion to CO2 is analogous to the production of CO2 that occurs when we dig up and burn fossil fuels.”

The Science article is titled “Global Charcoal Mobilization from Soils via Dissolution and Riverine Transport to the Oceans.” The lead author is Rudolf Jaffé from Florida International University. In addition to Stubbins, the co-authors include Yan Ding, also from Florida International University; Jutta Niggemann and Thorsten Dittmar from the Max Planck Research Group for Marine Geochemistry; Anssi V. Vähätalo from the University of Helsinki; Robert G.M. Spencer from the Woods Hole Research Center; and John Campbell from the U.S. Department of Agriculture Forest Service Northern Research Station.

The entire article can be viewed online at: www.sciencemag.org

Stubbins has a website detailing this and other work on black carbon at: http://www.skio.usg.edu/?p=research/chem/biogeochem/blkcarbon

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Slash-and-burn activities source of oceanic black carbon

August 14, 2012

For years, “slash-and-burn” techniques were used to clear Brazil’s massive Atlantic Forest.  Although the large-scale burning was halted in 1973, the black carbon left behind from those forest fires is still draining into the area’s rivers and eventually into the ocean. For the first time, a team of scientists, including Aron Stubbins from the Skidaway Institute of Oceanography, has studied this carbon outflow and produced estimates of the amount of black carbon being introduced to the ocean. Their study has been published in the August issue of Nature Geoscience. Stubbins was one of seven co-authors of the paper. Thorsten Dittmar from the Max Planck Research Group for Marine Geochemistry in Oldenburg, Germany, and Eduardo de Rezende from the Universidade Estadual do Norte Fluminense in Rio de Janeiro, Brazil were the lead authors.

Photo Courtesy: Laboratorio de Ciencias Ambientais, Universidade Estadual do Norte Fluminense, Rio de Janeiro, Brazil

Humans have used fire extensively as a tool to shape the Earth’s vegetation. Brazil’s Atlantic Forest once covered 1.3 million square kilometers and was one of the largest tropical forest ecosystems on Earth. Because of the extensive burning for land-clearing, the forest has been reduced to less than ten percent of its original size.

The research team estimated that prior to 1973, the burning of the Atlantic Forest generated as much of 500 million tons of black carbon. The burned plant material initially sits on the ground or is absorbed into the soil, but eventually it is carried away by rainfall drainage into creeks, rivers, and, eventually, the ocean.

One river in the area carries 2,700 tons of dissolved black carbon to the ocean annually.

“We scaled our findings up to cover the remainder of the watershed,” said Stubbins. We estimate the former-forest contributes 50,000-70,000 tons of dissolved black carbon to the marine environment.”

What is not known is the fate of the dissolved carbon once it reaches the ocean. Black carbon is thought to be very slow to decay in the oceans. So the black carbon entering the oceans maybe accumulating as a carbon store that locks carbon away from the atmosphere for hundreds if not thousands of years. Its influence on marine life is also unknown at present.

“What is certain is that slash-and-burn will continue to ravish forests creating more black carbon in the soils left behind,” said Stubbins. “This study shows that the effects of these fires extend on the carbon cycle extend through both time and space. Although the initial impact is immediate and local, the long lasting export of black carbon spreads the impact of these fires throughout the global ocean.”

The article can be viewed at: www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1541.html.