Migration of heavy metals in vegetable farmlands amended with biogas slurry in the Taihu Basin, China

Vegetables and related soils amended with biogas slurry samples were collected from Taihu Basin to evalute current levels of local metals pollution and related migration of the metals (Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb) in soil–vegetable system. The results showed that the concentrations of Ni, Zn, Cd and Pb in vegetables and related soils exceeded the upper limits of evaluation standards. Moreover, the concentrations of Mn, Co, Ni, Cu, Zn, As and Pb in the soils were shown significant correlations with OM (Organic Matter).The metal transfer factor (TF) was found highest for Cd followed by Zn > Cr > Pb > Mn > Cu > Ni ≈ Co > As, which were dependent on the vegetable species. Amaranth was observed to have a greater heavy metals absorption capacity compared with other vegetables that would pose a potential health risk to the consumers.