This longstanding mystery is addressed in a review by the University of Zurich’s Michael Schmidt, Susan Trumbore from Max Planck Institute of Biogeochemistry in Jena and an international team of scientists that is published in the October 6 issue of the journal Nature. The researchers suggest ways to improve the ability to predict how soil carbon responds to climate change as well as land use and vegetation change.
For many years, scientists thought that organic matter persists in soil because some of it forms very complex molecular structures that were too difficult for organisms to break down.
In their Nature review, however, Schmidt and colleagues point out how recent advances, from imaging the molecules in soils to experiments that track decomposition of specific compounds, show this view to be mistaken. For example, the major forms of organic matter in soils are in the forms of simple bio-molecules, rather than large macromolecules. Charred residues from fire provide a possible exception, but even these have been shown to decompose.
If molecular structure is not causing organic molecules to persist, what is? The team contends that the average time carbon resides in soil is a property of the interactions between organic matter and the surrounding soil ecosystem. Factors like physical isolation, recycling, or protection of molecules by minerals or physical structures like aggregates, or even unfavorable local temperature or moisture conditions, can all play a role in reducing the probability that a given molecule will decompose.
Although soils are teeming with bacteria (there are approximately 40 million cells in a gram of soil), they typically occupy less than 1% of the available volume, and are usually clustered in ‘hot spots’. In some situations where microbial populations are sparse, for example in deep soils or far from roots, it may just require a long time for suitable conditions to arise that allow a molecule to be broken down. In other locations, freezing temperatures may inhibit microbial action.
Why is this important? Currently, models we use to predict how global soil carbon will respond to cli-mate change include little mechanistic understanding and instead use simple factors like temperature dependence that indicate acceleration of decomposition in a warmer world. This assumes that temperature is the major limitation to decomposition, whereas other factors may dominate.
The decomposition-warming feedback predicts large soil carbon losses and an amplification of global warming, but in fact the authors argue this approach is too simplistic. In the Nature review, the scientists make several suggestions where current improvements in understanding could be built into models, improving our ability to predict how soil carbon responds not only to climate but to land use or vegetation change. (ST)Original data are published in:
Susanne Hermsmeier | Max-Planck-Institut
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Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...
Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.
From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...
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