Sea water may contain up to about 1 gram gold per 500 tons of sea water. How to separate out was the problem. No real good answer yet. Most promising seem to be to genetically modify some of the microorganisms found near the oceanic vents to take up the gold in giant vats of sea water, and then collect, dry, and burn the microorganisms to leave the gold. Even if they could do it 100% effective, it would not be financially or maybe ecologically sound until all current gold was made radioactive or something. Since gold doesn't readily corrode or chemically combine with other chemicals at environmental concentrations ( yes can be done in lab), it is easy to reclaim over and over.
Yes, the gold they made was radioactive and actually didn't last very long, less than 1/2 second. On the ship (Enterprise) we just tell the matter aracasackle that we want a pound of gold. By the way, have you read my blog entry? I would like some comments, please. it's my first attempt at poetry. Click blue #1 to left <-- under avatar
But if you check the radioactive isotopes on that link I posted you find that most of them decay by electron capture so although you lose your gold you get platinum.