Navigation Links
Methane climate change risk suggested by proof of redox cycling of humic substances

The recent Yokahama IPCC meeting painted a stark warning on the possible effects of gases such as methane which has a greenhouse effect 32 times that of carbon dioxide. Now a team of Swiss-German researchers have shown that humic substances act as fully regenerable electron acceptors which helps explain why large amount of methane are held in wetlands instead of being released to the atmosphere. However, there are worries that if this system is disrupted it may enter into a vicious cycle to release large amounts of methane back into the atmosphere.

Wetlands, such as peatlands, have a high content of organic-compound rich humic soils, which are formed during the breakdown of biological organisms such as plants. When water levels are high, these soils remain wet, and so are starved of oxygen, causing the organic compounds to accept electrons from respiring bacteria - rather like the charging of a giant battery. This prevents these electrons from being used by methane-forming bacteria, and so prevents these bacteria from releasing methane into the atmosphere.

The researchers now found that this giant electrical reaction can also go into reverse, like the charging and discharging of a giant battery. As water levels drop due to periodic variations in weather, then the humic soils will tend to release the electrons to oxygen forming harmless water. However, there is a danger is that climate change could lead to higher water levels, causing these soils remaining submerged for a greater period, and so and the discharging process disappears thus leading to more methane formation.

Potentially even worse, increasing global temperatures may cause permafrost to melt, leading to the soils being charged by microbial activity with electrons but not discharged. This could release vast quantities of methane from the wetlands. This in turn causes a greater greenhouse effect, and so on in a potentially vicious cycle.

One of the two lead researchers, Andreas Kappler (Tubingen), who is also the secretary of the European Association of Geochemistry, said:

"From a scientific point of view, our study is a step forward in understanding the geochemistry of how the humic material in the world's wetlands store electrons and prevent the release of a massive amount of methane. It also shows that reversible electrochemical processes have the potential to have a large effect on the environment. There are uncertainties as to the exact extent, but we estimate anywhere between an extra 10% up to an extra 166% methane could be released. What it also shows that these are fragile ecosystems and that slight changes in their geochemical conditions could have dramatic consequences for the environment".

The world's wetlands cover around 5% of the planet's ice-free land surface, meaning that they are roughly equivalent in size to Australia: but they have a disproportionate effect on the planet's methane metabolism contributing between 15 and 40% of the global methane flux into the atmosphere. Wetlands include areas such as marches, swamps, bogs, and fens, and in fact the largest wetlands in the world are swamp forests of the Amazon and the peatlands of Siberia.

Commenting on the potential climate effect, Professor Ralf Conrad (Marburg, Germany) said:

"The study shows that humic substances can act as rechargable oxidants in flooded environments in the same way as it is known for inorganic nitrogen, sulfur, iron and manganese. Humic substances are ubiquitous constituents in the terrestrial biosphere and form a huge carbon reservoir. Now it has been shown that humic substances also control the microbially mediated electron flux in wetland ecosystems. This role has so far not been considered in models of global carbon cycling and climate change, but has a potentially great impact."


Contact: Press Office
European Association of Geochemistry

Related biology news :

1. Camels emit less methane than cows or sheep
2. A more potent greenhouse gas than CO2, methane emissions will leap as Earth warms
3. Methane leaks from palm oil wastewater are a climate concern, CU-Boulder study says
4. Substance in photosynthesis was at work in ancient, methane-producing microbes
5. Berkeley Lab-led project aims to produce liquid transportation fuel from methane
6. Tailored methane measurement services are to be developed for shale gas extraction, municipal waste
7. Microbiologists reveal unexpected properties of methane-producing microbe
8. U.Va. researcher: Methane out, carbon dioxide in?
9. Study finds novel worm community affecting methane release in ocean
10. Tom Bowmans Climate Report delves into Arctic methane controversy
11. Methane emissions from natural gas local distribution focus of new study
Post Your Comments:
(Date:6/9/2016)... June 9, 2016 Paris ... Teleste,s video security solution to ensure the safety of people ... during the major tournament Teleste, an international ... and services, announced today that its video security solution will ... to back up public safety across the country. The system ...
(Date:6/2/2016)... The Department of Transport Management (DOTM) of ... Dollar project, for the , Supply and Delivery ... IT Infrastructure , to Decatur ... Identity Management Solutions. Numerous renowned international vendors participated in the ... was selected for the most compliant and innovative solution. The ...
(Date:6/1/2016)... -- Favorable Government Initiatives Coupled With Implementation ... to Boost Global Biometrics System Market Through 2021  ... " Global Biometrics Market By Type, By End ... - 2021", the global biometrics market is projected to ... growing security concerns across various end use sectors such ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... ... June 23, 2016 , ... ... its second eBook, “Clinical Trials Patient Recruitment and Retention Tips.” Partnering with experienced ... this eBook by providing practical tips, tools, and strategies for clinical researchers. , ...
(Date:6/23/2016)... SILVER SPRING, Md. , June 23, 2016 ... evidence collected from the crime scene to track the criminal ... sick, and the U.S. Food and Drug Administration (FDA) uses ... Sound far-fetched? It,s not. ... whole genome sequencing to support investigations of foodborne illnesses. Put ...
(Date:6/23/2016)... 23, 2016  The Biodesign Challenge (BDC), a university ... to harness living systems and biotechnology, announced its winning ... New York City . ... showcased projects at MoMA,s Celeste Bartos Theater during the ... MoMA,s senior curator of architecture and design, and ...
(Date:6/23/2016)... ... ... In a new case report published today in STEM CELLS Translational Medicine, doctors ... being treated for breast cancer benefitted from an injection of stem cells derived from ... frequent side effect of cancer treatment. , Lymphedema refers to the swelling ...
Breaking Biology Technology: