Effects of planting patterns on the concentration and bioavailability of heavy metals in soils during wetland restoration

To understand the effects of planting patterns on heavy metals in soils, the total concentration, bioavailability, contamination level, and ecological risk of heavy metals in soils from Jinjiang Estuary wetland were investigated. The results showed that after a wetland restoration, the concentrations of Cu were as follows: before wetland restoration > after wetland restoration > control group. The concentrations of Cr and Pb before and after the wetland restoration were all higher than those of the control group, whereas only some of the values of Zn were higher than those of the control group. Likewise, the bioavailability of Cu was roughly the same as that of the control group, those of Cr and Zn were higher than those of the control group, and that of Pb was less than that of the control group. Generally, after the wetland restoration, the bioavailabilities of Cu, Cr, and Pb decreased, but that of Zn increased. Moreover, the pollution level and ecological risk of Cu decreased, while those of Cr, Zn, and Pb increased. In addition, the comprehensive potential ecological risk of the Jinjiang Estuary wetland was moderate for Cu, Cr, Zn, and Pb before and after the wetland restoration. These results suggest that during a wetland restoration, the mixed vegetation types and planting density could influence the total concentration and bioavailability of heavy metals, affecting the pollution level and ecological risk of heavy metals to some extent. This study would be helpful in providing subsequent scientific research to restore wetlands.