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How Pine Trees Can Make Water Pristine

03/03/2014 12:59 EST | Updated 05/02/2014 05:59 EDT

Anyone who has watched the hit series, Survivorman knows survival in any environment is based on the availability of fresh, safe water. As Les Stroud points out in almost every episode, the body can last for weeks without food but only a few days without water. This presents an incredible challenge for anyone left alone in the elements. More importantly, it presents a crisis for the upwards of 2.6 billion people who live without access to this fundamental resource.

In the most recent episodes of his show, Stroud has circumvented this conundrum with the help of a modern water filtration system, known as the LifeStraw. The product is based on the same technology as kidney dialysis machines. When water is introduced into the straw a 'hollow fiber' matrix inside traps and kills microbes. The result is safe water sent directly into the mouth. While this might work in a single-person survival scenario, when it comes to widespread use, there are limitations.

To counter this, researchers and public health officials have explored natural options to turn undrinkable water pristine. Back in 1984, the first such method, called slow sand filtration, was developed. The simple and rather inexpensive setup involved the use of a supporting layer of rocks, a stabilizing middle layer of small stones and then a top sterilizing layer consisting of fine sand. As the water flowed through, bacteria, viruses and other contaminants would get stuck inside the sand leaving what came out the bottom safe to drink.

The mechanics of sand filtration have since been examined in depth through testing in developing countries and there have been successes. But there is a rather unfortunate caveat: the filter can never be left to dry. Water must be constantly sent into the filter to keep it moist and working optimally. In areas where water is plentiful, this is no problem but should water be scarce, this presents a significant problem.

To deal with this hurdle, scientists have focused on other natural means to filter water effectively. Yet many are fairly expensive, time-consuming and require significant human effort. However, one option has proven to be less painstaking and could be the way of the future.

Plants are marvels of nature although most of the magic manifests inside far beyond our ability to see. One of the most incredible -- and understudied -- aspects of their nature is their internal use of water, better known as hydrodynamics. As water is pulled into the plant, it somehow goes through a process where contaminants and pathogens are neutralized, leaving nothing but safe water to drink. How that happens, however, has yet to be fully understood though some mechanisms have materialized.

One fascinating facet involves an internal structure of trees, better known as xylem. Upon closer investigation of the cellular makeup and function, researchers have learned that it is not solid, but rather filled with tiny pores that can trap everything from chemicals to microbes. As water pushes through this section of the plant, anything foreign is trapped making it unable to cause harm. In essence, xylem mimics the same hollow fiber technology used in dialysis machines and the LifeStraw.

The function of xylem's filtration formed the basis of a paper published this week by a team from the Massachusetts Institute of Technology. The premise was that xylem could help to filter water and make it safe to drink. To test this, the group took a branch from a living tree, in this case pine, removed the bark, put a container over top and underneath and then ran water through it.

The results were incredibly positive. Not only was there flow, but also enough to produce upwards of four litres per day. That's more than enough to quench the thirst of most people. But the real delight came when they purposefully contaminated the water with either a pink dye or the bacterium, Escherichia coli, prior to filtration. As if by magic, the wood turned the pink water back to clear and removed all signs of the microbe.

To demystify the mechanism, the team took a closer look at the xylem. Not surprisingly, they found both the dye and the bacteria caught inside the matrix, unable to move. The xylem worked exactly like its synthetic counterparts; the only difference was that this was a fully sustainable and incredibly inexpensive method.

The results of this study suggest that making freshwater may not be as difficult as once thought. Although this may not entirely solve the fresh water crisis for the billions of people who need it, this advancement does present a good start.

More types of plants -- pine isn't universal -- should be tested for their effectiveness and a list of potential water filtration trees to be sought out and cultivated should be formed. If that comes to pass, then a new boom of tree planting may begin. But instead of improving the aesthetic value and oxygenating capacity of an environment, all very worthwhile goals, this one will be aimed at keeping the water safe and the people, including Survivorman, healthy.

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