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The seas hoard gold treasure, Bugs have green skinny hearts

Q: How much gold is there in the seas and oceans and why don't we get it out of the water instead of mining? (Bert, Vaals, The Netherlands)

Q: Does seawater contains some ppm [parts per million] of gold? (S, Tamilnadu, India)

Gold thin film [Michael W. Davidson and the Florida State University, © 1995 - 2005, used with permission]

A: Yes, the sea is laden with gold! But, unfortunately it is so dilute that its concentrations are orders of magnitude smaller than the parts per million you mention. It’s more like parts per trillion. The oceans contain an average gold concentration of about 13 billionths of a gram per liter of seawater (13 ppt). This concentration corresponds to a protozoan-size speck swimming in a quart of water.

Of course, the ocean contains many quarts of water, so even such microscopic traces still add up to a lot of gold — 25 billion ounces of gold, worth about 10 trillion dollars (7.6 trillion Euros). Humans have unearthed only 3 billion ounces over recorded history.

Actually, gold concentration varies between 5 to 50 ppt, depending on location. The Bering Sea contains the highest reported concentration.

Undissolved gold — solid stuff — litters the sea floor. We’ve found "big" (by undersea standards) deposits along the mid-ocean ridges of the Atlantic and Pacific Oceans. In fact, Peter Herzig of the Aachen University of Technology in Germany and his colleagues found microscopic motes as large as five micrometers across along the Valu Fa Ridge 0.7 miles (1.1 km) beneath the Pacific Ocean.

Where does the gold come from? Where tectonic plates spread, cold water seeps down, encounters hot rocks, and leeches out gold.

So far, it costs too much to mine or extract it from the sea to make a profit. In an expensive experimental operation, Herzig used a submarine named Nautile to dredge up the gold from almost a mile below the sea surface.

As we’ve seen, gold concentration in seawater is so pathetically small that the cost of pumping the water is greater than the value of the gold.

"Ocean mining has never proven economically viable, and I think that's still the case," says Jeffrey Christian, managing director of CPM Group, New York City, commodities and precious metals market analyst.

Further Reading:

Wikipedia: Gold

GoldFever.com: Gold from the sea by Timothy McNulty

Q: Do mosquitoes have hearts? (Lendwood, U.S. Navy ship)

A: Yes they do. In fact, all insects have hearts but they sure don’t look like our big mammalian hearts. A mosquito’s heart is a long, skinny, fragile tube that runs along its back, starting near the anus, to the chest cavity (the thorax). The tube actually extends to its head but only the abdomen part has muscles to contract and is called the heart. See figure.

A bug’s heart — contained in the abdomen and indicated by the red line. [John Meyer, North Carolina State University]

A bug’s heart contracts (as ours does) to squeeze green (or colorless) blood forward through the heart from chamber to chamber toward the thorax. There the heart simplifies into a plain tube (the aorta) that carries the blood (called hemolymph) to the head. The blood sloshes around in the head, bathing the brain and organs. When each chamber of the heart relaxes, valves open and blood rushes into the heart from the body cavity — but not via blood vessels.

The blood circulates freely in the body cavity making direct contact with internal tissues and organs. It delivers nutrients, salts, and hormones and whisks away wastes with each heartbeat. The rate varies among insect species, typically in the range of 30 to 200 beats per minute (compared to our 80 bpm).

Further Reading:

North Carolina State University: Insect circulatory system by John R. Meyer

(Answered March 25, 2005)