Copper accumulation process and rhizosphere mechanism under different water conditions in riparian wetland of Poyang Lake, China

Purpose Conducting research about the metal accumulation process of wetland plants and relevant rhizosphere mechanism can help better understand the biogeochemical behavior of metals in riparian wetland. However, little relative information is available for riparian wetland. Methods In this study, we explored the copper accumulation process of dominant plant of Artemisia and rhizosphere mechanism under different water conditions (flooding condition [FC], dry condition [DC] and alternate dry and flooding condition [DFC]) in riparian wetland of Poyang Lake. Results The results indicated that continuous or intermittent flooding may impede the accumulation and transformation of Cu by Artemisia . The correlation and multivariate analysis indicated that rhizosphere pH, Cu fraction and iron plaque on root surface can significantly influence Cu accumulation process. The transformation of exchangeable fraction to carbonate bound fraction and organic fraction under DFC and FC treatments of Cu may impede its accumulation in Artemisia . Formation of iron plaque under DFC and DC treatments can enhance the Cu accumulation in roots, but impede the translocation of Cu to aboveground tissues. Higher rhizosphere pH under DFC and FC treatments may impede the translocation of Cu by enhancing formation of iron plaque. Additionally, the translocation factor and root/aerial Cu content indicated that Artemisia has the potential for phytoextracting Cu, but the significant decrease of its biomass with Cu addition indicated that Artemisia is not suitable for phytoextracting Cu polluted soil, especially under DFC and FC treatment. Conclusion DFC and FC treatments can significantly impede the Cu accumulation processes and ability by changing rhizosphere characteristics and decreasing plant growth.