Yes, there are quite a few standards for different soils with regard to heavy metals. But , they need reoriented exercise in order to establish , since such heavy metal contamination is high varying in nature...and tolerance to crop response ..as an example

The best criterion is the laboratory examination of the soil sample, by taking a volume of the surface soil if it is non-agricultural lands, and then analyzing it by means of an X-fluorescence.

But if it is agricultural, the sample is taken at several depths in order to know the depth in which the heavy metals are present so that it does not affect the agricultural crops and accumulate in them.

In Poland, there is a document called "ROZPORZĄDZENIE

MINISTRA ŚRODOWISKA w sprawie sposobu prowadzenia oceny zanieczyszczenia powierzchni ziemi". The limit values of the selected elements depend on, i.a. the purpose of the land.

We use WHO

Cd = 3 mg/Kg,

Cu =100 mg/Kg, Pb =84 mg/Kg, Cr= 30 mg/Kg,

Good evening, mr. Shahmirnoori!

We have a National Legal Standard since 2009 wich defines Orientation Values for:

1, soils and groundwaters with different levels for Prevention;

2.Investigation for agricultural soils ;

3.Investigation for residential/industrial soils and,

4.Investigation for groundwaters.

The level for "quality reference" is determined by each state.

Unfortunatelly is in portuguese, but the words in the colunm head are similar to english. In page 14 You can read the table of element/substances.

You can find this National Resolution in:

http://www2.mma.gov.br/port/conama/legiabre.cfm?codlegi=620

Take care!