Friday, February 23, 2007

El Dorado The secret of the soils and the mystery of the carbon sinks part 2

As we previously noted here. Our current knowledge is ambiguous whether the rest of the CO2 is being detached by oceans or by terrestrial sinks (soil or vegetation) (Baldocchi et al., 1996).Indeed the missing carbon sink around 20% of the gcc is one of the unanswered questions for the IPCC.

Vesicular Arbuscular Mycorrhizal fungi (VAM, or just AM) for its role in phosphorus transport as well as sequestration of massive amounts of carbon in the durable form of glomalin which is the threadlike remains of dead VAM lacing undisturbed soil.
Phosphorous isn't the only thing VAM transports.

Fungal hyphae play a greater role in the spread of bacteria in the soil than was previously suspected. . . For the first time, scientists have been able to prove that bacteria are able to travel through the soil on the mucous membrane of living fungi. . .

As Science daily reports.

“For the bacterium a harmful substance is not harmful,” explains Wick. “It simply breaks down the carbon compounds, producing the energy and substances that it needs to live.” But before it can do this it has to get at its ‘food’. Air and lack of moisture present insurmountable obstacles. “This is why certain pollutants are broken down so slowly in the soil. Often it is not a lack of biochemical capacity, but rather a lack of contacts.” The scientists at the UFZ are therefore studying the paths followed by the bacteria.

Mycelia appear to act as a kind of underground highway for bacteria. This is the conclusion reached by Lukas Wick and his team. In the laboratory experiment they succeeded in demonstrating that the bacteria move through the soil on the mycelium. The ingredients: one pollutant, separating layers made of glass pellets, uncontaminated soil and a bacterium called Pseudomonas putida. The bacteria have to fight their way through all these layers to reach the phenanthrene, their ‘food’. This polycyclic aromatic hydrocarbon is a widespread pollutant produced during every combustion process: at petrol stations, in car exhausts, during forest fires, in cigarette smoke and in old municipal gas works.

“We deliberately make the bacteria work their way upwards against gravity so that people can’t say there could be a small amount of water trickling down and carrying the bacteria with it,” says Wick. “We have tried to rule out any doubts and objections from potential critics.” The bacteria made it to the top only in places where there was a mycelium running through the soil. In the identical parallel experiment without a mycelium the bacteria were unable to surmount the barriers. “With this paper we have shown that there is an infrastructure.”

The fungi used in the experiment, Fusarium oxysporum, is not the only one in soil, and the pollution gobbling bacteria studie

When exploring the history of Geochemistry in Russia the first name one comes across is VladimirIvanovich Vernadsky (1862-1945). The Vernadsky Institute for Geochemistry and Analytical Chemistry in Moscow is named after him. He is considered to be the father of geochemistry, biogeochemistry,radiogeology and cosmochemistry in Russia. L.Margulis states in the foreword of the English version of Vernadsky’s book The Biosphere that “Just as all educated westerners have heard of Albert Einstein, George (Gregor) Mendel, and Charles Darwin, so all educated Russians know of V. I. Vernadsky”

From 1881-1885 Vernadsky was a student of the physical-mathematical faculty (natural-scientific section) of St. Petersburg University. The most influential of his teachers was V. Dokuchaev, who was a founder of modern soil sciences and of a large naturalist school. V. Dokuchaev became the supervisor of Vernadsky’s master and doctoral theses. Dokuchaev’s integrative approach of considering soil formation as a product of different environmental factors, including the interactions between living and dead matter, might have laid the cornerstone of V. I. Vernadsky’s theory of biosphere. In 1888 V. I. Vernadsky left St. Petersburg to study mineralogy in Munich. He then moved to Paris in 1889 where he worked with Le Chatelier, who helped him to find his dissertation subject in the field of silicate mineralogy. One year later Vernadsky settled in Moscow, where he started a twenty-year professorship in crystallography and mineralogy at Moscow University. In this period, Vernadsky founded a new scientific school detached from soil sciences and mineralogy.

In the interaction between dead and living matter Vernadsky not only focuses on the solid Earth but also emphasizes the effect of living organisms on the composition of the atmosphere. Vernadsky points out that the “gases of the entire atmosphere are in an equilibrium state of dynamic and perpetual exchange with living matter”. He refers to a presentation of J. B. Dumas and J. Boussingault given at a conference at Paris in 1844 when stating that living matter can be taken as an “appendage of the atmosphere”

In his book The Biosphere Besides qualitative aspects of processes in the biosphere, Vernadsky also aims at a quantitative understanding of these processes. The numbers he derives for the quantity of free oxygen on Earth, the global net primary production, or for the total biomass on Earth vary significantly from recent data but the approach of creating global budgets of biogeochemical cycles was very innovative when The Biosphere was written and is still a major subject of present biogeochemical research. Vernadsky uses quantitative considerations in particular to illustrate the effect of the totality of living matter on element migrations on a global scale and to support his idea of living matter as a major geological force on the Earth’s surface. In addition to budget calculations Vernadsky derives an expression for the “kinetic geochemical energy of living matter”. The kinetic geochemical energy of an organism is related to its mass and its speed of transmission.The latter depends on the size of the organism and the optimal number of generations per day and is normalized to the surface area of the Earth. Vernadsky frequently refers to the geochemical energy in The Biosphere especially to emphasize the enormous biogeochemical potential of microorganisms.

As we previously identified in the terrestrial biosphere vegetation accounts for 20% of the carbon sink,the vadose zone the soils and detritus materials 80%.

Environmental groups who have other agendas argue against pastoral farming of livestock due to the emissions of methane.The methanogenic bacteria that inhabit all animals, as well as rice paddies and “conservation wetlands” are not alone in the microbiological biosphere.Other inhabitants are methanotrophic bacteria that inhabit soils.These are consumers of methane, we also observe they respond to increases in atmospheric methane.

These estimated cell-specific CH4 oxidation rates are sufficiently high to allow not only maintenance but even growth on atmospheric CH4 alone.

The constancy of biomass over geological time is a part of the empirical generalizations Vernadsky formulates at the beginning of The Biosphere:

1)During all geological periods there have never been traces of abiogenesis (direct
creation of a living organism from inert matter).

2)Throughout geological time no azoic geological periods have ever been observed.

3a)Contemporary living matter is connected by a genetic link to the living matter of
all former geological epochs.

3b)The conditions of the terrestrial environment during all this time have favored the existence of living matter and conditions have always been approximately what they are today.

4) In all geological periods the chemical influence of living matter on the surrounding environment has not changed significantly; the same processes of superficial weathering have functioned on the Earth’s surface during this whole time, and the average Chemical compositions of both living matter and the Earth’s crust have been approximately the same as they are today.

5) From the unchanging processes of superficial weathering, it follows that the number of atoms bound together by life is unchanged; the global mass of living matter has been almost constant throughout geological time. Indications exist only of slight oscillations about the fixed average.

6) Whichever phenomenon one considers, the energy liberated by organisms is principally (and perhaps entirely) solar radiation. Organisms are the intermediaries in the regulation of the chemistry of the crust by solar energy.

In The Biosphere, Vernadsky extensively discusses the different roles of chemo- and photoautotrophic bacteria in the biosphere and he highlights the importance of anaerobic bacteria in biogeochemical processes occurring in subsurface environments in several sections. The appreciation of the importance of microorganisms in element
transformations at the Earth’s surface is another example of Vernadsky’s scientific foresight.


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