I don't think that you will find much of a link. Many heavy metals strongly bind to organic matter. So the metals can be bound to allochthonous or autochthonous organic matter. Moreover, as different fractions of organic matter may vary in their isotopic composition, there is already a variability in the soil, even within one source of organic matter. You might be able to use carbon isotopes if you monitor e.g. trace metals in a river. In this case many metals are transported attached to organic matter molecules. So if you have different sources of organic matter to the river that differ in their stable isotopic composition, you can use this to identify the source area.

Another way that may work: If together with metals also PAHs were deposited and if PAHs differ in their isotopic signature, then you can use the PAHs for the source appointment and then guess that the metals have the same source. But this may be highly speculative. So I would rather try to use d13C signals to learn about organic matter turnover and then think about how this affects the trace metals in the soil.

Since you mentioned altitude, I'm wondering if you have in mind co-deposition of airborne organics and heavy metals. 

The C isotope signature of soil varies with the biota that inhabit it,  e.g. there is a well-documented difference between C3 and C4 plants.  Heavy metals may indeed be bound to organics and I presume may consequently influence their half lives.  I would not initially try to unravel such complicated processes in the field, especially as a research topic for a higher degree.