Saturday, March 31, 2007

Adaptability of the Polar biosphere to changes in Irradiance

As is known high energy particles from different sources SPE ,ACR,SCR and GCR have similar photochemical effects on the ozone structure.there are still open questions concerning their effects in the atmosphere.This is seen with Gladysheva et al 2001 in analysis of the ice cores for the maunder minimum where GCR is the dominant transformer.

This of course is a big question the transfer and transformation of energy in the solar –terrestrial system and observable phenomena in the middle and lower atmosphere and the climatic oscillations.

The questions being :

The frequency,the environmental impact and the scale of catastrophic events in say geomagentic reversal where the ozone loss may be complete.

Pekka Verronen identified some of these with the complexities of the Sodankylä Ion and Neutral Chemistry Model (SIC) in studies of the short-term effects caused by SPEs.

The reconstruction of high energy events as seen here is by analysis of the nitrate levels in the ice cores. Changes to the phenotype of microbial populations in situ is another that has been overlooked.

The levels of nitrates in ice cores need to be correlated against the taxa and levels of microbial populations as amelioration (de-nitrification) has been found.The change of ratio of the carbon-nitrate-phosphorous will see changes of the taxa populations whose adapability is identified to change with nutrient levels and uv and irriadiance spectra,here the measurement is in biologic or metabolic time which is different to chronological time (age ) of the populations.

The ability of the polar biosphere both terrestrial and oceanic to rapidly adapt to changes in Uv , irriadiance spectra and radiation levels suggest that ozone depletion in the polar areas is not unusual.

In the Arctic microorganisms are not only resistant to freezing, but some can metabolize at temperatures down to -39 ºC During winter, this process could be responsible for up to 50% of annual CO2 emissions from tundra soils. Cold-tolerant microorganisms are usually also drought-tolerant. Microorganisms are tolerant of mechanical disturbance and high irradiance. Pigmentation protects organisms such as lichens from high irradiance, including UV radiation, and pigments can be present in considerable concentrations. Cyanobacteria and algae have developed a wide range of adaptive strategies that allow them to avoid, or at least minimize, UV injury. However, in contrast to higher plants, flavonoids do not act as screening compounds in algae, fungi, and lichens.As a group, microorganisms are highly adaptive, can tolerate most environmental conditions, and have short generation times that can facilitate rapid adaptation to new environments associated with changes in climate and UV-B radiation levels.

Cyanobacteria are well adapted to changeable conditions involving low and high radiation levels (including UV-B radiation), and cycles of desiccation and rehydration, increasing and decreasing salinity, and freezing and thawing. This gives them a great ecological advantage and allows them to be perennial.

In the Antarctic to date, metabolic activity has been observed in melted accretion ice at 3 °C and 1 atm (Karl et al,1999), viable microbes have been found at depth in the Vostok ice core (Abyzov et al., 1998), and microbes active at sub-zero temperatures have been reported in South Pole snow (Carpenter et al., 2000). Recent data on the isotopic composition of nitrous oxide in Vostok ice cores suggest that this gas has been biologically modified within the ice (Sowers, 2001), providing indirect evidence for active metabolism within solid ice.

The ability of microorganisms to change their spectrum of fluorescence to changes in spectra of irriadiance levels is one of the more interesting questions.


Post a Comment

<< Home

Web Counters