The Joys of Walking Across An Icy Field

Education has met its goals, not necessarily when it has landed you a dream job—which I think is an illusion for the vast majority of people who have slaved in the past and who are working now— but when it can intensify the sensual and intellectual pleasures of the simplest acts of life—like walking to work.

103_9414
Same field as being described but from another day.

Weather-wise, we have had an erratic month of February in Montreal, with more than the usual cycles of freezing and melting. One day, after a morning of snow and an afternoon of freezing rain, the snowscape was glazed with a thick, milky ice, thick enough to support the weight of a toddler. It was cold for a few days afterwards, but subsequent rain transformed the veneer. I was reminded that with every subzero drop, the forms of snow and ice, like the size of all crystals, depend on how quickly the temperature drops and on the impurities and imperfections that seed them. During my 2 km-walk that morning, I experienced different textures and densities.  This is because sources of dust, pools of water,  their depth and amount of surface exposed to air are all variable and not every spot is equally affected by wind and footsteps.

Over two thousand five hundred footsteps that gave me an uplifting return on by body’s investment in adenosine triphosphate, ATP. (For the uninitiated, ATP is not a drug.  It is the currency of cells, the facilitator for all of our energy-requiring reactions. It’s what chloroplasts produce when photosynthesizing before creating glucose, and it is what our cells create when oxygen breaks down the metabolites of that same sugar. )

As I felt the unmonotonous sequence of pressures around my boots, each different area that I walked on created a unique sound  Since childhood, my favourite sound of that type is that of thin ice shattering above an air pocket. I was also reminded that the frictional coefficient of naturally-formed ice varies significantly. That morning no one else braved the -22 oC windchill factor. So with no one watching, I was a free 54-year old, giving myself a little run and testing to see how far I’d glide on various sections of the ice field.

The way light interacted with all the surfaces also accentuated their differences. There were sparkles from icy particles acting as tiny prisms; there were lakes of yellow-orange as the rising sun caught expanses of smooth surfaces; and other parts of the frozen field glistened with different hues. Every hue corresponded to a different frequency, suggesting a unique interaction of matter with light energy.

103_9405Another benefit of immersing myself into the walk was that it lifted the weight of the thoughts about the oncoming day. It also dissipated any of the usual worries that the condensation of water in my breath was beginning to accumulate and cool my neck-warmer. If anything, the journey was far too short. I was tempted to turn 180 degrees and repeat the walk with even more attention to detail…Oh but, wait, I said to myself. The fact that I did not indulge in an extended trek was not a wasted opportunity. After all, there was the journey home that afternoon.

 

 

BMAA and ALS: A Close Look at Eutrophication

The overall equation representing one of life’s ultimate achievements, photosynthesis, is the biggest oversimplification you will find in any basic science book on the planet. It shows water, carbon dioxide and sunlight as reactants and glucose and oxygen as products. It does not hint at the intricate cascade of events that have to transfer electrons from water to carriers to chlorophyll; on to more carriers and other chlorophyll molecules and still more shuttle bus-like molecules and eventually to carbon dioxide and other reactants of the Calvin cycle.

From http://www.biologyreference.com/Ph-Po/Photosynthesis.html
From http://www.biologyreference.com/Ph-Po/Photosynthesis.html

It overlooks the accessory pigments that help chlorophyll capture more energy from the sun. It ignores the components of the membranes that separate hydrogen ion concentrations supplying the voltage needed to make the reaction facilitator, ATP, and all the enzymes that accelerate the entire food-making process of plants.

Reaction rates in chemistry are controlled by their slow intermediary steps. Photosynthesis and subsequent plant growth rates are controlled by the amount of light, which initiates the process; by temperature, which controls the carbon-dioxide fixing rate; by water-availability and by certain limiting ions. In other words, there is usually ample carbon dioxide available, but other minor, yet crucial substances are often scarce and control the growth of both land and aquatic plants. For algae, such limiting ions, mainly phosphate(PO43- and nitrate(NO3) are needed to make those behind the scene-molecules just mentioned: nitrogen-containing enzymes and ATP, which have N-compounds and phosphate, and they are also needed to synthesize genetic material.

But what happens when limiting ions suddenly become available in greater quantities to bodies of water? They cause eutrophication, which is a state of excess plant and algal growth. Although the process can occur naturally, humans are masters at accentuating it. Runoff fertilizer from nearby agricultural activities, sewage and industrial effluents all contain nitrates and phosphates, which directly lead to population explosions of algae, so called algal blooms.

hypoxia
http://www.sciencemag.org/content/321/5891/926/F1.large.jpg

As algal growth goes out of control, light has a harder time penetrating the water and its pH rises, both of which impact certain predators and shore plants. When excess algae die as part of their life cycles, their decomposition consumes dissolved oxygen, killing fish. Such hypoxic events are affecting over 245 000 square kilometers worldwide.

The foul smell of algal blooms is also a sign of more chemistry gone awry. Depending on the algal species that proliferate, eutrophication at times produces toxins that threaten drinking water supplies, recreational swimming and consumption of seafood. More specifically species of a group of photosynthetic bacteria, cyanobacteria,  produce compounds such as an enzyme-binding microcystin and the neurotoxin anatoxin-a, which mimics the neurotransmitter acetylcholine.

One of several microcytins, the LR refers to variant amino acids
One of several microcytins, microcystin-LR— the LR refers to the variant amino acids leucine and arginine.

In Canada, the Federal-Provincial-Territorial Subcommittee on Drinking Water recommends a maximum acceptable concentration of 0.0015 mg/L for total microcystins in drinking water, based on the toxicity of microcystin-LR. That is equivalent to 1.5 parts per billion, attesting to their high toxicity and to the fact that these compounds resist boiling.

Another cyanobacterial neurotoxin , β-methylamino-ʟ-alanine (BMAA), found in contaminated seafood and shellfish, drinking water supplies, and recreational waters—may be a factor in Lou Gehrig’s disease (amyotrophic lateral sclerosis, or ALS) and possibly other neurodegenerative conditions.

BMAA
BMAA

The toxin is produced by 95% of the cyanobacteria genera tested, and although it is not one of the 20 amino acids building blocks used by organisms, it does get mistakenly incorporated into proteins.

Accumulation of BMAA in the proteins of nerve cells, which need to last a lifetime, would provide a mechanism for how the toxin might biomagnify. “The problem with neurons is they do not divide, as a general rule, so over time they accumulate damaged proteins, and once they reach a critical level, it causes the cell to undergo apoptosis [cell death],” explains Rachael Dunlop, a researcher with the Heart Research Institute in Sydney, Australia.

Dunlop and others also found that at least in test tubes, a transfer RNA enzyme mistakenly picks up BMAA and incorporates it into proteins. More recently Dunlop and another researcher have mentioned that genes in certain individuals make them more sensitive to BMAA, which unfortunately is not presently screened for in municipal water analyses.

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