Effect of rainwater-borne hydrogen peroxide on manure-derived Cu and Zn speciation distribution and bioavailability...

Pot experiment was conducted to examine the effects of rainwater-borne hydrogen peroxide (H₂O₂) on transformation of Cu, Zn from pig manure in soils and its resulting impacts on the growth of Cu and Zn uptake by a rice plant. Results showed that the exogenous application of H₂O₂ significantly improved the rice biomass and yield. Addition of H₂O₂ into the soils led to reduced uptake of soil-borne Cu and Zn by the rice plants and this had a significant effect on reducing the accumulation of Zn in rice grains. It was indicated that the increased pH in soil might play important role in reducing Cu and Zn content in rice. Furthermore, Cu and Zn content in exchangeable form and carbonate bounded form dramatically decreased in soil, on the contrary, the organic combination state increased significantly in H₂O₂ treatment. The findings point to a potential research direction that rainwater-borne H₂O₂ in nature may help to change morphology of heavy metals in natural soil environments, but further study is still needed to explore the related mechanisms in Cu and Zn in manures and paddy rice field receiving rainwater-borne H₂O₂.