Re: Where will the waters of the River Tyne (Newcastle, UK) end up?

The North Sea has a lot of tidal action, so the river waters flowing into it don't take long to mix in to the point that they are indistinguishable from North Sea water. This probably happens on the timescale of days. I'm attaching a schematic diagram (from The OSPAR Commission Report) of circulation in the North Sea:



I've marked the rough position of the Tyne with a green dot. Some of the water from the Tyne will make it into the Baltic Sea, but most of it will follow the dominant U-shaped circulation pattern (down the coast of Britain, around and up the Norwegian coast) into the Norwegian Sea. This circulation pattern takes about a year. It will then join the Norwegian current (illustrated in this map) and circulate around the Arctic for a long, long time (order hundreds of years). But, as I said, we can't be too sure, since it's being mixed into waters potentially flowing in different directions.

I hope this helps.
Cheers,
Tetjana