Kensington. -- In the late 1970s I was a consultant to a construction company that was waterproofing the new Metro subway system in Washington. The sealant they had been using had been declared a carcinogen by the Environmental Protection Agency, and my task was to find a safe alternative that could be injected at high pressure into tiny cracks in the walls of the Metro stations.
The substitute I found, polyacrylamide, was a gelling agent used mainly for consolidation of loose soil around oil wells. Among its neat properties was that it could become like Jello within a minute of being mixed, and, when firm, it contained 98 percent water. Also, according to the manufacturer, it would hold its gelatinous condition as long as it stayed wet, which would be no problem in a subway station.
Another interesting property of polyacrylamide was that the Food and Drug Administration had approved it as a food additive -- a point which I included in my write-up to EPA asserting the safety of the new waterproofing material. (A food additive, by the way, is not the same as an ingredient. Motor oil, I recall, is also a food additive; small amounts get into food from processing machinery, so the food industry has secured food-additive status for motor oil.)
After the drums of polyacrylamide arrived, I spent several months in the field showing the waterproofers how to mix, handle and inject it. The field guys liked polyacrylamide; they said it was easier to handle and didn't have the strong chemical odor of the previous material. They also assured me, when I saw that the leaks were not being stopped as fast as I expected, that it worked at least as well as the previous stuff.
After several weeks of seeing how hard it is to stop leaks, I got an impression about water. One day, after returning from a day at a Metro station, the company president stopped at my office to see how things were going. I said, "You know, John, water is like God -- " At which point he leapt in an said, "Yeah, we know about water, it moves in mysterious ways."
The word hydrogen means "water maker." Hydrogen is the simplest and lightest chemical element. Its atom consists of a single proton and one electron. When hydrogen combines with oxygen, the explosive reaction produces water.
In 1993, I spent the summer measuring the amounts of hydrogen that come from electric cars when their batteries are charged. My measurements were to establish minimum ventilation requirements for new-house construction so that electric cars can be charged indoors without risk of explosion.
I built a test cell in a garage that was part of a detached house in Gaithersburg. The neighbors could see the electric cars being ,, delivered, and they knew I was doing some kind of testing. What they didn't know was that several times I had to stop the battery charging because the accumulation of hydrogen was sufficient, if ignited, to blow the walls off the garage and maybe even lift the whole house off its slab.
During those tests, I thought about hydrogen's explosive ability to create water. Also during that time it was reported in the news that a spacecraft, which had been launched in the mid 1970s, had just reached "the edge of the solar system." The edge of the solar system was defined, according to a scientist at Goddard Space Flight Center, as "the place where the sun's high-speed wind slams into the interstellar hydrogen;" the spacecraft, which was still sending back data, had sensed a shockwave where the solar wind was hitting interstellar hydrogen atoms.
I called the guy at Goddard to find out the composition, velocity and density of the solar wind. The solar wind blows past the earth at about a million miles an hour, he told me. He said its density near the earth is about 120 protons (hydrogen nuclei) per cubic inch, with an additional dozen or so helium nuclei, plus an occasional heavy ion such as carbon, iron, silicon or oxygen.
For billions of years the solar wind has carried hydrogen from the sun at a rate of nearly 2 million tons per second. The earth intercepts about one part in 2 billion of that flow. Solar hydrogen nuclei, when caught in the earth's magnetic field, spiral into the atmosphere where they react with oxygen to form water molecules, which are too heavy to be blown back into space. (Solar helium nuclei that arrive here acquire electrons to become helium atoms; but they are so light they may spend only a few thousand years here, including maybe a few days in a child's balloon, before one day, near the top of the atmosphere, they get pushed by sunlight back into the solar wind for the rest of the several-hour trip to the eternity of interstellar space.)
I calculate that water from solar hydrogen is being created in the upper atmosphere at a rate of one kilogram each second. If the solar wind has been blowing at its present rate for 3 billion years, it can account for half of the water now here.
The number of hydrogen atoms in our bodies is greater, by the way, than that of any other chemical species. And most of the hydrogen in our bodies and on the earth may have come from the sun, and relatively recently at that.
Perhaps the sun provides not only the energy that drives the winds and rains and makes the crops grow and our cars go. The hydrogen in the water that comes from the top might have spent billions of years inside the sun. In fact, some of the hydrogen in your body might, only a few weeks ago, have been on the sun. Recently arrived solar hydrogen, now in the form of water, might be working its way toward cracks in subway station walls. It's probable.
Robert Burruss is an engineer who writes about technology and society.