Water: Part One

Note: This program first aired on June 23, 2012. 

The late spring and early summer of 2012 has proven to be a damp one here in Maine. While not as biblical as the spring a few years ago, when it rained every day for weeks on end, I still hear complaints about the showers and lack of sun everywhere I go. I admit, I hear them in my own head and feel them in my own heart as well. And having just returned from a trip to the desert, where the sky is inevitably blue and sun always shines, the damp has felt especially insidious.

I’d like to take this time however, and remind us all, how blessed we are. Water is precious, a fundamental requirement for life on earth, and increasingly rare. Our physiology demands it at regular intervals on a daily basis. Modern industry uses (and abuses it) in vast quantities. Our food supply is critically dependent on fresh water, 70% of all appropriated freshwater currently goes to irrigation of crops, so where there is water shortage, there is food insecurity. Over 7 billion people live on this planet, and by 2025, over half of them will live in areas subject to severe water stress. Millions of people on the Indian sub continent and in South America rely on glacial melt water as their primary water supply. With global glaciers in fast retreat and several projected to disappear in the coming decades where will those people’s children get water from? Subtropical regions the world around are already typically desert zones. As climate instability increases in coming decades, these regions, home to millions of people, are expected to experience intensified drought. The leading cause of death globally is diarrhea, overwhelmingly due to lack of access to clean water.  When I said we are blessed, I meant it. Clean water, so necessary for life, literally falls from the sky here.

We primarily get our water (for industry, for drinking and municipal use), from one of two sources: deep underground aquifers (referred to as ground water) or surface water (water that is readily available in ponds, lakes, rivers). Ground water is the form of the vast majority of liquid fresh water on Earth. According to a UN World Water Development report “Ground water supplies nearly half of all drinking water in the world” and is crucial for the well being of people, especially rural poor people, all over the world.

We should (but don’t) think of ground water as a non renewable resource. Water moves readily through the hydrologic cycle: it evaporates from the land and ocean surface, and is transpired from vegetation into the atmosphere. From there it condenses from a gas back to a liquid in the form of clouds and eventually rain or snow. That precipitation returns the water to the surface of the Earth, where it infiltrates the soil, or runs off and returns to surface water reseviors. Much of the water that infiltrates the surface is taken up by vegetation or simply evaporates back into the atmosphere. Only a small fraction eventually makes it down into the ground water aquifer. The rate of recharge depends not only on how much water hits the land surface, but also on the depth of the saturated layer, and the porosity of the underlying geological layers the water has to travel through. Many ground water aquifers are being depleted, due to extraction rates that exceed inflow or replenishment rates. Basically, we take more water out than is going back in through natural processes, thus making ground water use unsustainable.

So the next time you are thinking about complaining about mosquitos or black flies-insects that require water in which to lay their eggs and provide habitat for their larva, pause and remember: their presence is an indicator of our good fortune and our richness; abundant clean water that falls from the sky.

References:

“Environment and Development Challenges: The Imperative to Act” http://www.unep.org/home.asp
www.unep.org/pdf/pressreleases/Blue_Planet_synthesis_paper.pdf  This is a summary statement from all Blue Planet Award Winners.

 “Managing Water under Uncertainty and Risk” United Nations World Water Development Report  4 http://www.unwater.org/ Cheery reading.

https://www2.ucar.edu/atmosnews/news/2904/climate-change-drought-may-threaten-much-globe-within-decades Report from the National Center for Atmospheric Research (NCAR).

http://www.ipsnews.net/2011/09/200-million-depend-on-melting-glaciers-for-water/ Excellent 2011 article that provides an overview of the glacial meltwater issue.

Gender: Part One

Note: this program first aired on June 16, 2012.

We humans tend to think of gender as a fixed and clear cut matter. Males are males, females are females, and they each have a fixed and distinct biological role in sexual reproduction. Unfortunately, many of our human cultures have not displayed much tolerance for individuals who have blurred the lines of our clear cut ideas about gender.

What I would like you to know today is that in nature, gender is not as fixed or defined as we humans would like to think. Initially gender in the form of separate sexes arose as a result of sexual reproduction, which is simply the recombination of genetic information. In its simplest form, an individual is “encoded” by two sets of genetic information, one from one parent and one from the other. Without going into detail about the steps of meiosis (the process of making sperm and eggs) understand there is nearly infinite variation on the sets of genes that each parent can give, which is why each individual that results from sexual reproduction is completely and utterly unique.

When put this way, the obvious question is: Why do parents have to be two separate genders? Why couldn’t two individuals simply exchange gametes? Why is there gender at all? It turns out, initially, there wasn’t gender. This makes sense, the earliest organisms on earth were bacteria, and bacteria don’t have gender (nor do they generally reproduce sexually, but that is a different matter). Sexual reproduction in higher multicellular organisms was achieved through isogamy (a genderless exchange of gametes—many fungus and algae still reproduce this way).  Due to natural diversity, some individuals had larger gametes and some had smaller gametes. Over time, it seems that the most successful matches were between a larger gamete and a smaller one. This pushed natural selection towards favoring these two sizes of gametes, and separating the world into individuals who make big gametes and those who make small ones. Essentially, it is to your benefit to do either one of two things: invest a lot of time and energy into making a few large gametes (we now these now as eggs), or invest your energy into making lots and lots of small, short lived gametes, that you can continue to make anew your whole life (we call these sperm). The smaller and more mobile and less energy intensive the better, or the larger and more stable the better. In the evolution of sexual reproduction, the middle ground falls away.

This brings us back to the original question: gender. There is then indeed a biological basis for gender. Some individuals make large gametes, the eggs or ovum. We recognize those as female. Other individuals make smaller gametes, called sperm. We recognize those as males. But that is truly a simplification. As we will discover in coming weeks, gender is truly a human construct, and as usual, nature, in its infinite intelligence, elegance and practicality has something more amazing and beautiful to show us.

References:

Personal communication with Dr. Ann Cleveland. May 2012. Working in Academia has it advantages, including having a biologist for a boss. Over lunch, Ann enlightened me as to the origins of gender.

Sperm Biology: An Evolutionary Perspective By T. R. Birkhead, David J. Hosken, Scott Pitnick ( online exerpt, Google Books)

The origin and evolution of gamete dimorphism and the male-female phenomenon: (abstract only): http://www.sciencedirect.com/science/article/pii/0022519372900070

Phase Change

Note: This program first aired on June 9, 2012.

Phase change. It’s a term that refers to the change of a state of matter. When a substance changes from solid to liquid, or liquid to gas it is said to change phase. What makes phase change interesting is that there is a set energetic pattern associated with it, and both the natural world, and human industry have incorporated that energy in useful ways.

When a substance, any substance, changes from a solid to a liquid, or a liquid to a gas, it requires energy. Energy must be absorbed by the substance for this to happen. We know this. It takes energy for ice to melt right? Or liquid water to boil away to steam.  As the molecules of the substance absorb more energy, they move more. The more and further they move, the ‘looser ‘ substance’s structure becomes. At a certain point, the molecules absorb enough energy that they are behaving differently enough to appear as a different state of matter.

One wonderfully reassuring facet of nature is its symmetry. In this case, if energy is absorbed in one direction of phase change, the opposite happens when we reverse the phase change. When a substance goes from liquid to solid, or gas to liquid, energy is released. The molecules must release all that extra energy in order to slow down enough to get close enough to each other to go into a denser “lower energy’ state of matter. And of course, we understand this too; we have to cool water off to freeze it solid.

If you keep this concept in mind, you will recognize it in many places. Its why your refrigerator works, why the propane tank gets cold when you run it, why sweating works to cool us off, why panting helps dogs. Sweating, and panting are just operations that utilize the physics of evaporation. Our (and our dogs’) bodies are producing a liquid and taking advantage of the fact that turning it into a gas will remove energy from the system, in this case, our bodies. That is why sweating cools us off, evaporating that water off our skin absorbs energy, the extra heat we are trying to get rid of.

A refrigerator is an elegant example of how we use phase change in both directions to our advantage. We can construct a simple model of a refrigerator by imagining a tube in a closed loop. Half of it is inside a box, and half is outside. We put a substance in the closed loop that wants to be gas at room temperature (or even a little cooler). This means that left to its own devices, it at room temperature it will readily absorb energy and boil, changing from liquid to gas. Humans have figured out that if they compress that gas into a liquid, it will release energy. A refrigerator is simply a system that takes that substance, compresses it to a liquid form, pumps it into the space to be cooled, allows it to evaporate in the tube (hence cooling the surrounding area), pumps it out of the space to be cooled, compresses it back to a liquid (thus releasing the heat) and back in and back out, and around and around it goes. Evaporation happens inside the refrigerator absorbing energy, condensation happens outside the refrigerator, releasing energy. That’s why its warm behind the fridge—its not because of the motor, its because the heat that was in the stuff inside the fridge has been absorbed and moved out, via the substance in the tube (or coils—lots of tubes). And what is this substance? In most domestic refrigerators modern refrigerant gasses similar to the chloroflourocarbons of ozone layer fame are used, rendered less dangerous by having the chlorine removed. 

What is remarkable to me is the simplicity and consistency of this pattern. It doesn’t change, when things condense, they release heat. Period. When things evaporate, they absorb energy, no questions asked. With frenetic pace of life today and the unprecedented opportunities and distractions we face in every moment, I find these indisputable facts infinitely reassuring.