Chernobyl a Breeder reactor

The ability of biological species to adapt to adverse environments is one of the paradoxes of Ecological science.

How the exclusion of some “players” from the” marketplace” will allow for smaller players to dominate the market due to enhanced adaptability.

An interesting paper from the Albert Einstein College of Medicine of Yeshiva University shows the evolutionary adaptability of the Fungal Oligarchs the inhabitants of the Chernobyl nuclear reactor.

The Finding could trigger recalculation of Earth's energy balance and help feed astronauts

Scientists have long assumed that fungi exist mainly to decompose matter into chemicals that other organisms can then use. But researchers at the Albert Einstein College of Medicine of Yeshiva University have found evidence that fungi possess a previously undiscovered talent with profound implications: the ability to use radioactivity as an energy source for making food and spurring their growth.

"The fungal kingdom comprises more species than any other plant or animal kingdom, so finding that they're making food in addition to breaking it down means that Earth's energetics—in particular, the amount of radiation energy being converted to biological energy—may need to be recalculated," says Dr. Arturo Casadevall, chair of microbiology & immunology at Einstein and senior author of the study, published May 23 in PLoS ONE.

The ability of fungi to live off radiation could also prove useful to people: "Since ionizing radiation is prevalent in outer space, astronauts might be able to rely on fungi as an inexhaustible food source on long missions or for colonizing other planets," says Dr. Ekaterina Dadachova, associate professor of nuclear medicine and microbiology & immunology at Einstein and lead author of the study.

Those fungi able to "eat" radiation must possess melanin, the pigment found in many if not most fungal species. But up until now, melanin's biological role in fungi—if any--has been a mystery.

"Just as the pigment chlorophyll converts sunlight into chemical energy that allows green plants to live and grow, our research suggests that melanin can use a different portion of the electromagnetic spectrum—ionizing radiation—to benefit the fungi containing it," says Dr. Dadachova.

The research began five years ago when Dr. Casadevall read on the Web that a robot sent into the still-highly-radioactive damaged reactor at Chernobyl had returned with samples of black, melanin-rich fungi that were growing on the reactor's walls. "I found that very interesting and began discussing with colleagues whether these fungi might be using the radiation emissions as an energy source," says Dr. Casadevall.

To test this idea, the Einstein researchers performed a variety of in vivo tests using three genetically diverse fungi and four measures of cell growth. The studies consistently showed that ionizing radiation significantly enhances the growth of fungi that contain melanin.

For example, two types of fungi--one that was induced to make melanin (Crytococcus neoformans) and another that naturally contains it (Wangiella dermatitidis)—were exposed to levels of ionizing radiation approximately 500 times higher than background levels. Both species grew significantly faster (as measured by the number of colony forming units and dry weight) than when exposed to standard background radiation.

The researchers also carried out physico-chemical studies into melanin's ability to capture radiation. By measuring the electron spin resonance signal after melanin was exposed to ionizing radiation, they showed that radiation interacts with melanin to alter its electron structure. This is an essential step for capturing radiation and converting it into a different form of energy to make food.

Dr. Casadevall notes that the melanin in fungi is no different chemically from the melanin in our skin. "It's pure speculation but not outside the realm of possibility that melanin could be providing energy to skin cells," he says. "While it wouldn't be enough energy to fuel a run on the beach, maybe it could help you to open an eyelid."

Innovation is the engine that drives change

Politicians are the same all over. They promise to build a bridge where there is no river.
Nikita Khrushchev

Following the last two g8 meetings the Combined academies of science have released two positive statements for this one in June.

The first is on innovation and protection of prosperity.

Innovation is the engine that drives economies. Countries support innovation to ensure dynamic economic advancement and prosperity, to gain competitive advantage internationally, and to improve the quality of life of their citizens and those of other nations. The latter is fostered through international collaboration, especially in research and development. At the very least, global collaboration requires greater promotion and funding, in priority areas such as sustainable energy, climate change adaptation and mitigation, natural hazards, biodiversity, water, and infectious diseases. It is important for governments to invest strongly in a spectrum of basic research, since the greatest benefits often arise from investigations in areas that are not the subject of international focus at a given time. Innovation faces a fundamental dilemma: the innovator bears the cost, but is not guaranteed the full returns of his or her efforts. Innovators facing immediate imitation are less likely to engage in costly efforts. In addition to their vital responsibilities for education and training, governments have therefore pursued a number of approaches to foster innovation, including the establishment of intellectual property rights such as patents and copyrights, the financial support of R&D and innovation through public funding or subsidies, and the productive use of public procurement. It is critical to establish an appropriate balance between strong government investment and removal of barriers to research and licensing.

Innovation and incentive are the ingredients to make technology advance exponentially, not repressive tactics such as carbon taxes, emission markets. Or cap and trade policies, these are the policies of intellectual deserts.

If for example we use lighting ,it will not be the banning of the incandescent lightbulb and replacement with fluorescent bulbs. The exponential jump will be as different from the candle to the Edison bulb.Here it will be the change to LED and nano based lighting systems.

In the second statement the Joint science academies’ statement on growth and responsibility: sustainability, energy efficiency and climate protection.

It is important that the 2007 G8 Summit is addressing the linked issues of energy security and climate change. These are defining issues of our time, and bring together the themes of growth and responsibility in a way that highlights our duties to future generations.

Last year our academies addressed a further important aspect of the challenges related to energy: the implications for security. We noted then that a key strategic priority will be a diversification of energy sources, as a way to address the wide variety of circumstances and resources, and to decrease vulnerabilities to a wide range of possible disruptions in supply.

Major investments and successful technological and institutional innovation will be needed to achieve better energy efficiency, low- or zero-carbon energy sources and carbon-removing schemes. A clear area for increased investment is energy conservation and efficiency. This has immediate and long-term benefits for local and regional health and environment, security of energy services and climate change, while having potential for local economic development and build-up of local technological capabilities

Against this background it will be necessary to develop and deploy new sources and systems for energy supply, including clean use of coal, carbon capture and storage, unconventional fossil fuel resources, advanced nuclear systems, advanced renewable energy systems (including solar, wind, biomass and geothermal energy), smart grids and energy storage technologies. Research focused on the energy field must be enlarged significantly. The InterAcademy Council (IAC) is preparing a report on these challenges, which will be available later this year.

It is urgent to increase efficiency in the global production and use of energy. Energy efficiency has been a major field for the G8 countries since the 2003 Evian Summit.Concentrating on energy efficiency is an effective contribution towards meeting the global energy challenges The implementation of measures to increase energy efficiency will depend to a decisive extent on financing options and technology knowledge. A sound financial and technological framework and improved global investment conditions will therefore be vital.


Once again innovation and incentive of which the obvious is r&d credits and accelerated depreciation on new technology.

Of course governments are not bound to follow these scientists it is only a consensus

Simultaneous Ionization response to high energy radiation

Ionospheric physics deals with the basic structure and variability of plasma within the upper atmospheres of the Earth and planets. Comparative studies foster both exploration and synthesis within diverse settings.

Using photochemical-equilibrium arguments applicable to the peak electron density layer on Mars and the E-layer on Earth, we can see basic agreement in scaling laws between the planets, and response to high energy variability.

The ionized component of a planet’s upper atmosphere depends on a blend of in situ production and loss processes, plus effects of transport of ionization into or out of the local region of interest. As described in basic texts on ionospheric physics.

The truly common input for all solar system ionospheres on a given day is the Sun’s photon flux, a simple function of heliospheric distance. All other effects are planet specific:
(1) rotation rate and solar obliquity conditions,
(2) the thermal structure, constituent reactions, and dynamics
of its neutral atmosphere,
(3) the degree to which energetic particles (of solar wind and/or magnetospheric origin) impinge upon its atmosphere,
(4) diffusion and electrodynamics associated with coupling from above, and
(5) tides, waves, and electrodynamics arising from coupling to regions below.

Simplifying assumptions employed in such a formulation affect scaling laws for
ionospheric behavior among the planets. If all planetary atmospheres had
(1) a single molecular gas that is photoionized to form a molecular ion,
(2) for which dissociative recombination is the dominant loss process,
(3) located in a dense atmosphere, making transport negligible, and
(4) with no magnetospheric or solar wind interaction (or considering latitudes and altitudes where they are small), then simple photochemical equilibrium would govern each planet’s peak electron density. Under such conditions, the daytime electron (and ion) density N is never far from the steady state value derived from ‘‘Chapman theory’’ [Chapman, 1931;


In 1997, the group, (International School for Advanced Studies, Trieste), tried to predict the behaviour of methane (CH4) in the interior of the giant planet Neptune.About 15 years earlier, scientists at Lawrence Livermore National Laboratory in the United States had concluded that extreme pressure inside Neptune, the solar system’s fourth largest planet (Jupiter, Saturn and Uranus are larger) causes methane molecules to completely dissociate, enabling carbon atoms to reassemble into carbon-only diamond clusters. Their analysis created this tantalising hypothesis:
Could a giant diamond mine be hiding in the core of Neptune? Simulations carried out at ICTP over the past seven years confirm that Neptune’s central core could indeed be loaded with diamonds. But the vast majority of the planet’s mass likely consists of hydrocarbon chains since less intense pressures found throughout most of the region would mean that the methane molecules only partially dissociate to create an endless series of carbon atom chains surrounded by hydrogen atoms list of chemical constituents despite the fact that it had once been counted—along with water (H2O) and ammonia (NH3)—as one of the planet’s three most abundant constituents. Similarly, the wafting of hydrocarbons from the interior into the atmosphere may also help explain why Neptune’s life-denying atmosphere is laden with hydrocarbons.
Jupiter and Saturn are believed to be compositionally much simpler than Neptune.

A single atomic species, hydrogen, makes up most of their mass, with traces of helium and other light elements. No experimental apparatus is presently able to recreate in the laboratory the extreme conditions found in the interiors of these two planets. Simulations are the only method available. And the picture that has emerged from simulations, which began in spring 2002, have proven quite interesting.

Extreme pressures and temperatures cause hydrogen to dissociate inside Jupiter and Saturn, much like methane in Neptune. But even more surprising is the observation that the pressure-induced transition from a molecular fluid to a dissociated fluid has been accompanied by a large and sudden increase in the density of hydrogen.In light of this finding, the current picture of Jupiter and Saturn as homogeneous fluid spheres will need to be dramatically modified to account for the sharp transition between a molecular fluid envelope and a dissociated fluid core. Is there any chance we will ever be able to verify this hypothesis? And, more generally speaking, how much trust should we place in the outcomes of numerical simulations?For those who are impatient, the answer may be soon forthcoming.

The spacecraft Cassini, launched by NASA in October 1997, will enter Saturn’s orbit during the first week in July to begin a four-year tour of the ‘ringed’ planet. By monitoring Saturn’s magnetic field and gravitational impulses, Cassini will provide a more detailed density profile of the planet that should help determine whether the atom clusters that my colleagues and I have ‘virtually’ squeezed in our computers are conveying the truth.

Enter Cassini

Titan is the only satellite in our Solar System with a dense atmosphere. The surface pressure is 1.5 bar and, similar to the Earth, N2 is the main component of the atmosphere. Methane is the second most important component, but it is photodissociated on a timescale of 107 years. This short timescale has led to the suggestion that Titan may possess a surface or subsurface reservoir of hydrocarbons to replenish the atmosphere. Here we report near-infrared images of Titan obtained on 26 October 2004 by the Cassini spacecraft. The images show that a widespread methane ocean does not exist; subtle albedo variations instead suggest topographical variations, as would be expected for a more solid (perhaps icy) surface. We also find a circular structure, 30 km in diameter that does not resemble any features seen on other icy satellites.We propose that the structure is a dome formed by upwelling icy plumes that release methane into Titan's atmosphere.

The very low abundances of Ar, Kr and Xe in Titan's atmosphere can be easily explained by our experimental findings. These gases are trapped in the aerosols, which are formed by UV photolysis of acetylene in their presence. When the aerosols fall down to the surface, they clean the atmosphere of these gases. A continuous supply of the radiogenic produced 40Ar from the interior can explain its small abundance in the atmosphere. 2. The originally soft and sticky photochemical aerosols, as found by us experimentally, were calculated to harden by spontaneous and radiation induces chemical cross-linking. Indeed the camera and other detectors were not covered by sticky aerosols and the intake ports were not clogged. 3. As we predicted, no lightning discharges were detected in the quiescent Titan atmosphere. Therefore, Titan's atmospheric chemistry is driven mainly by solar UV irradiation and not by electrical discharges. 4. The mixing ratios of the major gas phase species produced by UV photolysis of acetylene, as found experimentally: methylacetylene ; diacetylene ; divinyl ; and benzene were observed by the Cassini spacecraft in Titan's upper atmosphere, with an agreement within better than an order of magnitude. 5. The N:C ratio in Titan's aerosols was measured by the Huygens probe, but no results were published yet. UV photolysis of gas mixtures containing C2H2:HCN=10 yield aerosols with a ratio N:C=0.007 up to 0.01. Electrical discharges through a N2:CH4~10 gas mixtures yield a much higher N:C ratio. 6. We anticipate mountains not higher than 1900 m on Titan's surface.

What are of interest is the effects of photolysis from UV which retains its energetic values at distance from the sun.and or

The increasing effects of galactic CR intensity from lessening solar wind modulation, and Increased CR acceleration (Fermi Mechanism) from the inter stellar space due to proximity to the interstellar boundary.

NASA Hubble Space Telescope observations in August 2002 show that Neptune's brightness has increased significantly since 1996. The rise is due to an increase in the amount of clouds observed in the planet's southern hemisphere. These increases may be due to seasonal changes caused by a variation in solar heating. Because Neptune's rotation axis is inclined 29 degrees to its orbital plane, it is subject to seasonal solar heating during its 164.8-year orbit of the Sun. This seasonal variation is 900 times smaller than experienced by Earth because Neptune is much farther from the Sun. The rate of seasonal change also is much slower because Neptune takes 165 years to orbit the Sun. So, springtime in the southern hemisphere will last for several decades! Remarkably, this is evidence that Neptune is responding to the weak radiation from the Sun. These images were taken in visible and near-infrared light by Hubble's Wide Field and Planetary Camera 2.

Observations obtained by the NASA/ESA Hubble Space Telescope and ground-based instruments reveal that Neptune's largest moon, Triton, seems to have heated up significantly since the Voyager spacecraft visited it in 1989.

"Since 1989, at least, Triton has been undergoing a period of global warming percentage-wise, it’s a very large increase," said James L. Elliot, an astronomer at the Massachusetts Institute of Technology (MIT), Cambridge, MA. The warming trend is causing part of Triton’s frozen nitrogen surface to turn into gas, thus making its thin atmosphere denser. Dr. Elliot and his colleagues from MIT, Lowell Observatory, and Williams College published their findings in the June 25 issue of the journal Nature.

Since 1989 Triton's temperature has risen from about 37 on the absolute (Kelvin) temperature scale (-392 degrees Fahrenheit) to about 39 Kelvin (-389 degrees Fahrenheit)


Therefore as we can see from the observations the increased solar system planetary response (warming) in the outer planets is caused by the solar mechanisms

Why the cheese on the moon is green

In 1991, as Apollo 12 Commander Pete Conrad reviewed the transcripts of his conversations relayed from the moon back to Earth, the significance of the only known microbial survivor of harsh interplanetary travel struck him as profound:

"I always thought the most significant thing that we ever found on the whole...Moon was that little bacteria who came back and lived and nobody ever said [anything] about it."


Microbes one of the simplest organisms in the biosphere. Having evolved over billions of years they retained the mechanisms to retain life in the harshest environments ,and to “resurrect” when environmental conditions and adequate nutrients become available.

The Earth looked remarkably different when bacteria first colonized the oceans and land. Oxygen was scarce. To many early plants, cyanobacteria and anaerobic bacteria, oxygen was a poison. The thin ozone layer that currently shields intense solar radiation was largely unformed. Bacteria, originating under global conditions very different from our present day, can be thought to be space travelers already: over time the generational records of microbes have sampled swings in environment here on earth that rival the differences between today's Earth and some of the more hospitable planetary outposts. The growing list of space-hardiness conditions include:

Vacuum conditions, with bacteria taken down to near zero pressure and temperature, provided suitable care is exercised in the experimental conditions.

Pressure, with viable bacteria after exposure to pressures as high as 10 tonnes per square centimeter (71 tons/sq-in). Colonies of anaerobic bacteria have recently been recovered from depths of 7 km (4.2 mi) or more in the Earth's crust.

Heat. Archaebacteria that can withstand extreme heat have been found thriving in deep-sea hydrothermal vents and in oil reservoirs a mile underground

Radiation, including viable bacteria recovered from the interior of an operating nuclear reactor. In comparison to space, each square meter on Earth is protected by about 10 tons of shielding atmosphere.

Long preservation, including bacteria revived and cultured after some 25 million years of encapsulation in the guts of a resin-trapped bee.

The Surveyor probes were the first U.S. spacecraft to land safely on the Moon. In November, 1969, the Surveyor 3 spacecraft's microorganisms were recovered from inside its camera that was brought back to Earth under sterile conditions by the Apollo 12 crew.

The 50-100 organisms survived launch, space vacuum, 3 years of radiation exposure, deep-freeze at an average temperature of only 20 degrees above absolute zero, and no nutrient, water or energy source. (The United States landed 5 Surveyors on the Moon; Surveyor 3 was the only one of the Surveyors visited by any of the six Apollo landings. No other life forms were found in soil samples retrieved by the Apollo missions or by two Soviet unmanned sampling missions, although amino acids - not necessarily of biological origin - were found in soil retrieved by the Apollo astronauts.)

Space historians will recall that the journey to the stars has more than one life form on its passenger list: the names of a dozen Apollo astronauts who walked on the moon and one inadvertent stowaway, a common bacteria, Streptococcus mitis, the only known survivor of unprotected space travel. As Marshall astronomers and biologists met recently to discuss biological limits to life on Earth, the question of how an Earth bacteria could survive in a vacuum without nutrients, water and radiation protection was less speculative than might first be imagined.

Meme to the policymakers look at the literature.

As we mentioned here the ecological communities of the biosphere, change rapidly to meet their changing levels of nutrients and energy. This is observable as shown by Ilya Prigorine and the Brusselator model of the BZ reaction.

A Belousov-Zhabotinsky reaction, or BZ reaction, is one of a class of reactions that serve as a classical example of non-equilibrium thermodynamics, resulting in the establishment of a nonlinear chemical oscillator.

The reactions are theoretically important in that they show that chemical reactions do not have to be dominated by equilibrium thermodynamic behavior. These reactions are far from equilibrium and remain so for a significant length of time. In this sense, they provide an interesting chemical model of nonequilibrium biological phenomena, and the mathematical model of the BZ reactions themselves are of theoretical interest.

Periodic variations of system properties in time, say by varying illumination in a light-sensitive Belousov-Zhabotinsky reaction (BZ) medium or another external forcing, leads to directed long-distance displacement of the spiral (Agladze et al. 1987; Davydov et al. 1988).ie resonant drift

An easy way to understand resonant drift is to consider a periodic series of short "shocks", say flashes of lights for the light-sensitive BZ medium. Due to stability and symmetry of a spiral wave, one such shock generically results in a displacement of the rotation centre of a spiral. If a series of shocks is timed so that each leads to a displacement in the same direction, this produces a drift.

This a skews the overlapped nitrogen/co2/hydrological cycle as the biosphere self organizes or corrects towards equilibrium, an objective it never meets due to a simple statement called Evolution ie homeostasis is never attained due to competition.

In an interesting review Codispoti shows that models and literature are far from equilibrium with the quantification of the oceanic nitrogen sink, due to perceptions of homeostasis in the paleo reconstructions.

Abstract. Measurements of the N2 produced by denitrification, a better understanding of non-canonical pathways for N2 production such as the anammox reaction, better appreciation of the multiple environments in which denitrification can occur (e.g. brine pockets in ice, within particles outside of suboxic water, etc.) suggest that it is unlikely that the oceanic denitrification rate is less than 400 TgNa−1. Because this sink term far exceeds present estimates for nitrogen fixation, the main source for oceanic fixed-N, there is a large apparent deficit ( 200 TgNa−1) in the oceanic fixed-N budget. The size of the deficit appears to conflict with apparent constraints of the atmospheric carbon dioxide and sedimentary 15N records that suggest homeostasis during the Holocene. In addition, the oceanic nitrate/phosphate ratio tends to be close to the canonical Redfield biological uptake ratio of 16 (by N and P atoms) which can be interpreted to indicatebthe existence of a powerful feed-back mechanism that forces the system towards a balance. The main point of this paper is that one cannot solve this conundrum by reducing the oceanic sink term. To do so would violate an avalanche of recent data on oceanic denitrification.

Biogeosciences, 4, 233–253, 2007
An oceanic fixed nitrogen sink exceeding 400 TgNa−1 vs the concept
of homeostasis in the fixed-nitrogen inventory
L. A. Codispoti

Quantification of the Biosphere, biomass forcing the hydrological cycle.

The biosphere is the area from the top of the trees, to several metres below the ground level on the terrestrial surface. Whilst life extends to the sea bottom inhabited by chemotropic organisms ,most life in the ocean is in the photic zone of the top 200m.

According to recent estimates the planetary biomass is 10*28 organisms ,most are unicellular micro-organisms. With the earths surface being ~500million km2 this means there is around 2x10*7 organisms per cm2.With the thickness of the biosphere being equal to the photic zone (200m) 10*3 organisms populate each centimeter of this layer, or 10*3 organisms for each cm3 of the geographical surface.

Quantification of the living biomass has increased vastly in recent times rising from 1000gt to 10,000gt..This means (if we scale) that each 1cm2 of the planetary surface contains 0.001g-0.01grams of living matter(biomass)On the terrestrial biosphere this is 1.-2 magnitudes higher in some areas. This thin film of living substance during photosynthesis produces around the same mass of matter each year. Over a period of 1000 years this equates to a layer of around 1m ,and over 1 million years a layer of more then 1 km. One gram of living matter requires the transpiration of 100-1000g of water, which is released into the atmosphere

The living biomass is distributed non uniformly being several magnitudes higher on land then in the ocean ,and several magnitudes higher in the forests. Taking into account the leaf area, we can assume the leaf biomass is 4 times that of other land areas Therefore land and forest is an important part of the hydrological cycle.

Buermann et al have an interesting paper entitled The changing carbon cycle at Mauna Loa Observatory .

The seasonal cycle of atmospheric CO2 at the MLO, with a maximum at the beginning of the growing season (May) and a minimum at the end of the growing season (September/October), records the "breathing" of the northern hemisphere (NH) biosphere, that is, the seasonal asynchrony between photosynthetic drawdown and respiratory release of CO2 by terrestrial ecosystems

Abstract.

The amplitude of the CO2 seasonal cycle at the Mauna Loa Observatory (MLO) increased from the early 1970s to the early 1990s but decreased thereafter despite continued warming over northern continents. Because of its location relative to the large-scale atmospheric circulation, the MLO receives mainly Eurasian air masses in the northern hemisphere (NH) winter but relatively more North American air masses in NH summer. Consistent with this seasonal footprint, our findings indicate that the MLO amplitude registers North American net carbon uptake during the warm season and Eurasian net carbon release as well as anomalies in atmospheric circulation during the cold season. From the early 1970s to the early 1990s, our analysis was consistent with that of Keeling et al. [Keeling CD, Chin JFS, Whorf TP (1996) Nature 382:146–149], suggesting that the increase in the MLO CO2 amplitude is dominated by enhanced photosynthetic drawdown in North America and enhanced respiration in Eurasia. In contrast, the recent decline in the CO2 amplitude is attributed to reductions in carbon sequestration over North America associated with severe droughts from 1998 to 2003 and changes in atmospheric circulation leading to decreased influence of Eurasian air masses. With the return of rains to the U.S. in 2004, both the normalized difference vegetation index and the MLO amplitude sharply increased, suggesting a return of the North American carbon sink to more normal levels.

They introduce an interesting lag phase of 2-3 years in the cyclical amplitude across the 11 years cycle.

The carbon-nitrogen cycle systems self organizing away from equilibrium

The Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) predicts that the Ca increase alone could stimulate terrestrial carbon (C) sequestration by 350–980 Gt (1 Gt " 1 # 1015 g) C in the 21st Century (Houghton et al. 2001).Sequestering 350–980 Gt C in terrestrial ecosystems requires 7.7–37.5 Gt of nitrogen (N) according to the calculation made by Hungate et al. (2003)

An interesting introduction in Luo et al Ecology, 87(1), 2006, pp. 53–63 a Meta analysis showing the requirements for AGW co2 sequestration and its requirements from the N cycle.

As is known the cycles tend to overlap in increases and decreases due to biogeochemical functions .An analogy is two dancers each listening to music at different tempos ,where corrections can be observed as stumbles etc as they correct and over correct in a state of self organization.

The close coupling between C and N cycles during ecosystem development over the earth history (Vitousek 2004 Nutrient cycling and limitation) and under elevated CO2 suggests that C and N processes are mutually regulated by each other. Although the past research in the CO2 research community has focused on regulation of C processes by soil N availability, regulation of N fixation and loss processes by C input under elevated CO2 is indeed an equally important issue in global change ecology that has to be carefully examined. The close coupling between C and N cycles also must be considered when we predict C sequestration in future global change scenarios.

Whist there are other important nutrient ratios that alter parameters this is a good comparative analysis.

Abstract. The capability of terrestrial ecosystems to sequester carbon (C) plays a critical role in regulating future climatic change yet depends on nitrogen (N) availability. To predict long-term ecosystem C storage, it is essential to examine whether soil N becomes progressively limiting as C and N are sequestered in long-lived plant biomass and soil organic matter. A critical parameter to indicate the long-term progressive N limitation (PNL)is net change in ecosystem N content in association with C accumulation in plant and soil pools under elevated CO2. We compiled data from 104 published papers that study C and N dynamics at ambient and elevated CO2. The compiled database contains C contents, N contents, and C:N ratio in various plant and soil pools, and root:shoot ratio. Averaged C and N pool sizes in plant and soil all significantly increase at elevated CO2 in comparison to those at ambient CO2, ranging from a 5% increase in shoot N content to a 32% increase in root C content. The C and N contents in litter pools are consistently higher in elevated than ambient CO2 among all the surveyed studies whereas C and N contents in the other pools increase in some studies and decrease in other studies. The high variability in CO2- induced changes in C and N pool sizes results from diverse responses of various C and N processes to elevated CO2. Averaged C:N ratios are higher by 3% in litter and soil pools and 11% in root and shoot pools at elevated relative to ambient CO2. Elevated CO2 slightly increases root:shoot ratio. The net N accumulation in plant and soil pools at least helps prevent complete down-regulation of, and likely supports, long-term CO2 stimulation of C sequestration. The concomitant C and N accumulations in response to rising atmospheric CO2 may reflect intrinsic nature of ecosystem development as revealed before by studies of succession over hundreds to millions of years.