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Terrestrial niches for thermosynthesizers
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In palisade cells of leaves a circulation movement occurs that is very conspicuous and
is called the protoplasm stream. In these palisade cells a thermal gradient
arises upon heating by sunlight absorption at the sunny leaf side and cooling by
transpiration at the
shade leaf side. The protoplasm stream circulates the cells contents
such as chloroplasts and mitochondria within this thermal gradient.
Within a leaf thermosynthesis therefore could occur, and early in evolution
plants may have made use of TS before they acquired photosynthesis
power upon endosymbiosis of a blue-green algae. This endosymbiosis resulted in the emergence of
chloroplasts, which increased the power of leaf cells.
Contemporary plants cannot obtain all their
free energy from TS: the efficiency of photosynthesis is far too large for that
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Celorganelles such as chloroplasts and mitochondria carried along by the
protoplasm stream in the thermal gradient present across a palisade leaf cell |
Nevertheless a significant role for TS in the leaf is proposed. This
would explain why plants use so much water (plant productivity depends
linearly on water consumption) and also gives a function to the protoplasm stream. The water would support TS, as its transpiration at the shade side
of the leaf maintains the thermal gradient across the leaf. As already remarked,
a counterargument exist for a major role for TS in photosynthesis,
as the latter is too efficient. But other processes may exist that
control plant growth rate and that depend on TS.
The linear dependence between plant growth and water use then
would follow from proportional couplings between water evaporation
and the leaf thermal gradient, a proportionality between this gradient
and TS, and a proportionality between TS and
plant growth.
TS cannot be the main energy source for plants, although the
structure of a palisade plant cell is favorable for TS.
In many other organisms cells are subject to a thermal gradient as well.
Many organisms are found at thermal gradients, many of which are man-made.
The following interfaces are natural thermal gradients:
- ground (or soil or stone)-air,
- water-air,
- ice-air,
- snow-air,
- ground-snow,
- water-ice
One can observe every day that moss grows on the warm ground and
extends into the cold air. Algae have often been
observed to grow on ice, which seems a quite hostile
environment. Across the entire globe the ocean-air interface is densely
populated by microscopic algae. Another interesting example is organism
growth in caves. Upon the melting of snow in the spring extensive fungal growth
(snow mold) becomes visible, which quickly dies off.
Mushrooms typically appear in the fall, when the air temperature drops below
the soil temperature.
The following figure depicts where in the ocean several of these
thermal gradients containing organisms. The thermohaline circulation
can be interpreted as a giant convection cell, in which water is cooled and descends at the poles, moves across the ocean bottom toward the tropics, where it rises, to be returned by currents at the ocean surface. The cycle time of
this convection cell is about 10 000 y. This thermohaline circulation is, by the way, a good example of large scale ordering by convection. Several of the thermal gradients associated with the circulation were just mentioned, but the thermocline was not. Many organisms - fish, algae - move back and forth through the thermocline, and it has already been previously proposed that organisms obtain an energetic advantage from such
vertical migrations [McLa63, McLa74].
TS gives a specific mechanism for this advantage.
Thermoclines can be detected by sonar, which can also detect fish. The following site gives an interesting tutorial on the practice of sonar and its use in finding fish:
Lowrance
thermocline
thermocline
thermocline + algae bloom
link
snow-air interface,
Some pictures of snow algae:
Source:
William Smith at Wake Forest University
water - ice interface
The following link gives an extensive discussion of life at the sea-ice interface.
Christopher Krembs and Jody Deming, University of Washington. The following quote is of special interest:
During the colder winter months, however, strong gradients of temperature persist throughout the ice, spanning from -2°C at the bottom of the ice in contact with seawater to -35°C at its wind-chilled surface.
geothermal ponds
link
oceanic front
link
caves
lichen
lichen
fluctuating light pattern on sea floor:
fig
a
Man-made terrestrial TS niches
Many man-made environments contain a thermal gradient as well,
and the presence of organisms is often conspicuous here.
An example is the biofouling on the hull of a ship.
On the hull the ship's temperature
may differ from the local sea water temperature: the ship is in good thermal
contact with the air and internal heat sources.
In air-conditioning units, central heating systems, cooling water
installations the presence of organisms is also conspicuous
(in condensors it has been called seagrowth).
Impeding biofouling and seagrowth in these machines require costly measures.
Our own houses contain microenvironments for the growth of microorganisms. Such growth will especially be noticed
where it results in health or damage to propertie. From
The Inside Story - A guide to indoor air quality
:
Some diseases, like humidifier fever, are associated with
exposure to toxins from microorganisms that can grow
in large building ventilation systems.
However, these diseases can also be traced to
microorganisms that grow in home heating and
cooling systems and humidifiers. Children, elderly people,
and people with breathing problems, allergies, and lung diseases
are particularly susceptible to disease-causing biological
agents in the indoor air.
and:
If using cool mist or ultrasonic humidifiers,
clean appliances according to manufacturer's instructions and refill
with fresh water daily.
Because these humidifiers can become breeding grounds
for biological contaminants, they have the potential for
causing diseases
such as hypersensitivity pneumonitis and humidifier fever.
Evaporation trays in air conditioners, dehumidifiers, and refrigerators
should also be cleaned frequently.
See also:
Your cooling tower may have a yeast infection
Many documents are available on the web about
diseases that can be associated
with microenvironments in the house in which thermosynthesis could occur:
on humidifier fever
and
on legionella
Thermosynthesis could occur almost everywhere on
earth, in natural as well as in man-made environments.
Careful observation would be required to distinguish it
from photosynthesis. The distinction may sometimes be easy, though;
electron transport during photosynthesis can for instance
easily be blocked by certain known inhibitors. It may be possible to isolate
algae mutants in the standard microbiological
ways that can grow on thermal cycling but cannot grow on light.
In environments without light (the earth's surface at polar nights,
thermoclines at great depths) observers should especially be on
the look out for the occurrence of TS.
A very interesting possible application of TS is a role as CO2 sink during modeling the global carbon budget, of importance for the greenhouse effect.
Woods Hole Research Center:
The Missing Carbon Sink
Editorial in Climatic Change (1996)
The CO2 Fertilization Factor and the "Missing" Carbon Sink
As interesting as terrestrial thermosynthesis niches are extraterrestrial thermosynthesis niches. The next page shows that thermosynthesis could occur almost everywhere in the Solar System: Extraterrestrial thermosynthesis niches.
Copyright © 1999-2005 Anthonie W.J. Muller