ARSENIC AND THE PRICE OF WATER
Dr. William M. Turner
Lets think about arsenic for awhile. We all know that arsenic was the main ingredient in rat poison. What we don't all know is that arsenic and radon occur in ground water. For those communities in the American West that depend on ground water this presents a major problem and opportunity at the same time.
Presently, health standards set a limit of 50 parts per billion (micrograms per liter of water) as the safe concentration for arsenic in drinking water. This is a very small amount. You can think of it by dissolving 5 grams of table salt in 64 tons of water. By 2000, the EPA must decide whether to decrease the safe amount of arsenic by a factor of ten or 5 grams of arsenic in 640 tons of water. To give you an idea of how much 5 grams is, a single packet of Knox's gelatin weights 6 grams. So, we could be looking at a standard that says if you have more than one packet of Knox's gelatin dissolved in 640 tons of water, its too much. Or another way to look at it is if there is more than 5 grams dissolved in 2,560,000 8-ounce glasses of water its too much.
Well, no one really knows what the limit should be today; but, if the safe limit is lowered, there are many communities that will either have to find water elsewhere or go to expensive treatment. Public policy will probably require a combination of both where possible. In other words, some better quality water must be found to mix with the poorer quality water. Best estimates are that 54,000 community water systems serving 254 million people in the United States alone will be affected. In Bangladesh, the high concentration of arsenic in drinking water has become a national tragedy.
Regardless of the solution, it is clear that water with a low arsenic content will become extremely valuable as communities seek better quality water.
So, where is better quality ground water to be found. First, we would look for low arsenic water in non-volcanic rocks. Second we would look for low arsenic water in areas where ground water moves very rapidly in the subsurface. As a general rule, the faster ground water moves, the lower will be its mineral content. That is, rapidly moving ground water has moved rapidly from its zone of recharge and has had less time to dissolve minerals from the rock through which it flows, hence its lower mineral content.
Communities looking for better quality ground water will have to be more careful about locating their water wells. Without proper ground water exploration tools, the cost of ground water exploration will be very expensive. A poorly located well may be very expensive to drill and construct and may produce water too high in arsenic. There will be opportunities for those who know how to explore for ground water and the best well sites. For more information on ground-water exploration contact AGW Consultants. They have an extensive web site on ground-water exploration but it is highly confidential (http://www.agwconsultants.com) and they will only accept projects if they can guarantee results.
