| Reference | Year |
| Country | Near to | Number of modalities | Number of replicates/ modality | Land use | Contamination type | Metals studied |
| Bakonyi et al. | 2003 | [34] | Hungary | Nagyhorcsok | 5 | 2 | arable land | experimental | Cd, Cr, Se, Zn |
| Bardgett et al. | 1994 | [35] | New Zealand | Levin | 8 | 3 | grassland | accidental | Cu, Cr, As |
| Chen et al. | 2009 | [36] | China | Lanzhou | 5 | 5 | arable land | mine | Cd, Cr, Cu, Pb, Zn |
| Ellis et al. | 2001 | [37] | Scotland | (not precised) | 6 | 1 | industrial area | industrial | As, Cd, Cr, Cu, Hg, Ni, Pb, Se, Zn |
| Georgieva et al. | 2002 | [17] | England | Gleadthorpe RC | 22 | 2 | arable land | experimental | Ni, Zn + Ni, Cu, Zn + Cu, Zn |
| Korthals et al. | 1996 | [28] | Netherlands | Wageningen | 16 | 8 | arable land | experimental | Cu |
| Korthals et al. | 1998 | [38] | Netherlands | Wageningen | 24 | 6 | arable land | experimental | Cu, Zn |
| Korthals et al. | 2000 | [39] | Netherlands | Wageningen | 5 | 6 | arable land | experimental | Cu, Zn |
| Korthals et al. | 1996 | [40] | Netherlands | Wageningen | 27 | 3 | arable land | experimental | Cd, Cu, Ni, Zn |
| Le Guedard et al. | 2016 | [41] | France | Saint Etienne | 9 | 3 | industrial area | mine | Al, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Tl, Zn |
| Le Guedard et al. | 2016 | [41] | France | St Cyprien | 4 | 4 | grassland | industrial | Al, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Tl, Zn |
| Le Guedard et al. | 2016 | [41] | France | Carcasonne | 3 | 3 | moors and heathland | mine | As, Cu, Pb |
| Li et al. | 2006 | [42] | China | Shenyang | 13 | 6 | arable land | industrial | Cu, Zn |
| Li et al. | 2011 | [43] | China | Shenyang | 9 | 4 | moors and heathland | urban | Cu, Zn |
| Liang et al. | 2006 | [44] | China | Shenyang | 18 | 3 | arable land | industrial | Cu, Zn, Cd |
| Nagy | 1999 | [45] | Hungary | Nagyhorcsok | 17 | 2 | arable land | experimental | Al, As, Ba, Cd, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sr, Zn |
| Nagy et al. | 2004 | [33] | Hungary | Nagyhorcsok | 14 | 2 | arable land | experimental | Cd, Cr, Cu, Se, Zn |
| Park et al. | 2011 | [46] | Sud Corea | Gijang | 2 | 7 | moors and heathland | industrial | Cd, Cr, Cu, Ni, Pb, Zn |
| Pen-Mouratov et al. | 2008 | [25] | Uzbekistan | Almalyk mine | 8 | 10 | grassland | mine | As, Cd, Cu, Pb, Zn |
| Peres et al. | 2015 | [47] | France | Rennes | 8 | 3 | grassland | industrial | Al, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Tl, Zn |
| Salamun et al. | 2012 | [24] | Slovakia | Kovohuty | 4 | 4 | grassland | industrial | As, Cd, Cr, Cu, Pb, Zn |
| Sanchez et al. | 2007 | [27] | Spain | Guadiamar river bassin | 8 | 17 | intertidal zones | accidental | Pb, Ni, Cu, Zn |
| Shao et al. | 2008 | [48] | China | Baoshan mine | 6 | 3 | moors and heathland | mine | Pb, Zn |
| Sharma et al. | 2014 | [49] | USA | Cleveland and Colombus | 2 | 22 | urban green space | urban | As, Cd, Cr, Pb, Zn |
| Smit et al. | 2002 | [50] | Netherlands | Heel | 30 | 5 | grassland | experimental | Zn |
| Tomar et al. | 2009 | [51] | China | Shenyang | 6 | 5 | arable land | industrial | Pb |