[Moosilauke]

That is absolutely untrue. Metallic mercury is extremely insoluble

Here is more support for your position. It's an interesting discussion of the whole mercury issue. One of its conclusions:

only the ionized fraction of atmospheric mercury, and NOT the elemental form that is contained in thermometers, is capable of entering the a lake's food chain, and that only a fraction of the ionized mercury that disperses into a lake ("perhaps between one and ten percent") would actually end up being converted to the organic form of mercury (e.g., methylmercury) that is further bioaccumulated and ultimately contained in fish.

[Bernard Marx]

I'm no chemist and am only repeating what I was told by chemists and biologists.

The mercury from gold mining that got into tributaries to the Sacramento River is no danger by itself. It accumulates in crevices and bottom mud. But anaerobic bacteria go to work on it, absorbing it into their systems. They in turn are eaten by snails, etc. which are eaten by fish. I'm not sure of the chemistry involved but mercury collects in animal tissues and is not excreted. It is passed on and on until it ends up in our frying pans and barbecues. I was told that's why mercury from batteries is dangerous in landfills. It's the absence of oxygen that allows it to be converted by bacteria into methylmercury. If I'm wrong blame my sources.