Biotechnology: Can hydrogels solve our water problem?

Darkfrog submitted, created time 2 months 1 week (www.nature.com)

I remember reading BIll Bryson's description of a pre-blight American chestnut tree. When he came to the transpiration of water, he said, "imagine how much metal and noise humans would have to use to move that many gallons water."

Well artificial water transport just got a bit quieter, even if it can't match the chestnut just yet. A tiny microtree made from the same type of gel used to make contact lenses has mimicked water transport in plants. Scientists say that it could be used to extract water in dry places or make more efficient cooling systems.

This is one of those things where we see it so often in nature that we don't realize how hard it is. In a plant, water is drawn into the roots by the force of other water molecules evaporating from the leaves. Cohesion and capillary action can keep the water molecules clinging to each other so that they climb up the plant's xylem, carring water-soluble nutrients with them. Large trees can keep these tiny, continuous threads of water connected for up to fifty meters.

What has been hard to figure out, though, is how they keep water under such low pressure from vaporizing and forming bubbles--xylem embolisms--that would break the thread and starve the tree. Natural plants use a network of cell membranes. This artificial plant uses a gooey, porous hydrogel based on poly(hydroxyethyl methacrylate). Yes, it needs the parentheses.

The researchers seem pleased, even saying that their invention has gone a step beyond natural plants because roots only absorb water that is already liquid, and the hydrogel can take up vapors.

The implications of this are good. One environmental problem that hasn't been getting much press is water. Not water pollution, just water. Las Vegas is a huge, growing city in the middle of the desert, sucking away at the groundwater faster than it can be replenished. How long until it runs out? The Southwestern states are already squabbling about who is diverting how much from the Colorado river. If systems based on this gel can extract water from above the water table or even pull it out of the air, then we might be able to solve or mitigate this problem.

Keywords: water trees biotechnology hydrogels plants transpiration chips ground water water economy water supply water quality water use