Heavy Metal Concentration in Soil

The greatest accumulation factor (which I assume to be some value measuring how much of each heavy metal builds up) is in a different location for each metal (Zn = Bradford Dale, Pb = Bonsall Moor, Cd = Wensleydale). I'm curious as to whether there's a particular reason for this.

Good data. I wish I knew what the soil was measuring (concentration of metal?). Interesting data overall. D4t4B4r0n out.

It is interesting that one mine can have a much greater concentration of one type of heavy metal than all the others, yet have relatively low amounts of the other metals. Bradford Dale had by far the highest concentration of Zn, but had the lowest concentration of Pb and the second lowest concentration of Cd.

As Cameron stated, the distribution seems fairly irregular. Can the metal be extracted? If it can't, how does it impact the agricultural economy worldwide?