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Outside magazine, July 2000
By Stephanie Gregory

What is the chemical composition of sweat? Does it change with how much you exercise or what you eat?

Robyn Dochterman, Minneapolis, Minnesota

Despite its odoriferous reputation, ordinary sweat—which is 99 percent water with trace amounts of salt, potassium, glucose, lactic acid, ammonia, amino acids, and uric acid—only smells a tad of ammonia and any proteins you ate the day before. (The mixture turns really rank only after it mingles with bacteria on the skin's surface.) Toxins in your sweat (ammonia, uric acid, and lactic acid) are waste expelled from your body, while salt is a critical sweat-producing agent. When your core temperature registers higher than 98.6 degrees, two-way pumps distribute sodium into your three million sweat glands. There, the salt acts as a magnet, drawing water by osmosis from the blood and other body fluids up through the glands. Upon reaching the pores, most of the salt remains behind (and is pulled back into the skin's lower layers by the same two-way pumps) while the sweat drips, gets absorbed by clothing, or evaporates—the crucial cooling part of this process. Here's where not all sweat is created equal: Ironically, well-conditioned athletes perspire more quickly and efficiently, producing what's called hypotonic, or watery, sweat. Per liter of coolant, athletes lose fewer electrolytes, such as salt and potassium, than couch potatoes. As for what you eat, any protein—whether from steak, cheese, or even garlic—appears in your sweat as amino acids. Chemically, they comprise less than one tenth of a percent of the solution. But aromatically —say, if you like to carbo load ongarlicky linguini aoili—they can pack a wallop.

Do any animals eat flowers as part of their regular diet?

R. Lawrence, Savannah, Georgia

Consider the sad fact of suburban gardening—that deer and other critters tend to treat flower beds as all-you-can-eat buffets—and the answer to your question is a resounding yes. For deer, rabbits, several species of birds, and even bears, flowers are like an organic dessert: tasty, but good for you, too. Their tender petals are easy to digest, contain plenty of essential amino acids and nitrogen, and are loaded with sweet nectar. In the forest, wildlife favorites include azaleas, wild lilacs, and, for bears, nutrient-rich wild lilies. Like Homo sapiens, animals take important cues from smell and know to stay away from flowers like the dreaded Douglas water hemlock, whose broad white blossoms contain coniine, which is deadly.

I've heard that water becomes purified as it falls over 30 feet of rocks. Is this true?

Ron Dobosh, Redondo Beach, California

Actually, a bubbling stream behaves more like a Brita filter than does a spectacular waterfall. But exercise caution when drinking: Neither miles of flowing river nor Niagara Falls will rid H2O of all its pathogenic microbes and pollutants. The purest-looking stream in the Arctic probably hosts a range of wildlife-introduced nasties, including giardia, fecal waste, E. coli, and the particularly aggressive parasite cryptosporidium. Water as far as 50 miles from a road or four-wheeler trail may contain gasoline leaked from vehicles, and if your brook's dozens of headwaters course by agricultural fields or an industrial plant, it likely also carries pesticides or toxic metals. Still, a stream works as a purifier, however imperfect, in three ways. First, hungry bacteria growing on rocks feed on animal feces as they're carried downstream. Second, gasoline tends to be vaporized in the churning water and carried off into the atmosphere. And finally, if the water gets direct sunlight, ultraviolet rays gradually kill off wildlife-borne microbes.Even so, bring—and use—bleach, iodine, or a portable ceramic filter. Heed the words of Glenn Patterson, a hydrologist with the U.S. Geological Survey: "Bottom line, there's no place you can be assured of having safe water." And, sadly, no purifier is guaranteed to remove pesticides and toxic metals, which remain for the entire trip to sea.

Is it true that moose can dive deep underwater?

Kathy Hoppa, Embarrass, Minnesota

The notion of real-life free-diving Bullwinkles most likely comes from the classic 1955 book North American Moose, in which Randolph Peterson, the late curator of mammals for the Royal Ontario Museum of Zoology and Paleontology, claimed that the herbivores "occasionally dive for plants in water over 18 feet deep." "Ridiculous," counters wildlife biologist Vince Crichton of Manitoba's Department of Conservation, who has studied the ungainly mammals for more than 30 years. "They float like corks!" Indeed, moose really are remarkably buoyant: Their four stomach chambers act like internal life jackets, and the hollow shafts of their winter fur perform like millions of tiny water wings—which is why a bobbing moose can swim upward of ten miles at a stretch. So what's behind the myth? It's actually not quite a falsehood. In the spring, when its fur is finer, Alces alces prefers to wade knee-deep in lakes and streams in search of its primary source of salt—lily pads, ribbon grass, pond grass, and assorted other aquatic veggies. But if the shallow-water eats are scarce, a moose will exhale and keep walking until its body is fully submerged, up to six feet. It's not quite the Jacques Cousteau–caliber 18 feet posited by Peterson, but it's enough to alarm canoeists who mistake the racks of underwater moose for driftwood.  

Illustrations: Jason Schneider

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