Effects of warming on uptake and translocation of cadmium (Cd) and copper (Cu) in a contaminated soil-rice system under Free Air Temperature Increase (FATI)

• Cd/Cu translocations in Indica and Japonica rice under FATI were investigated.
• Increased water-soluble Cd/Cu and reduced iron plaque boosted Cd/Cu uptake by root.
• Warming increased Cd translocation from root to shoot and Cd distribution in shoot.
• Cd accumulation in grain was positively correlated with accumulation in shoot.
• Simulated warming significantly increased Cd/Cu concentration in rice brown grain.

Global warming has received growing attentions about its potential threats to human in recent, however little is known about its effects on transfer of heavy metals in agro-ecosystem, especially for Cd in rice. Pot experiments were conducted to evaluate Cd/Cu translocation in a contaminated soil-rice system under Free Air Temperature Increase (FATI). The results showed that warming gradually decreased soil porewater pH and increased water-soluble Cd/Cu concentration, reduced formation of iron plaque on root surface, and thus significantly increased total uptake of Cd/Cu by rice. Subsequently, warming significantly promoted Cd translocation from root to shoot, and increased Cd distribution percentage in shoot, while Cu was not significantly affected. Enhanced Cd uptake and translocation synergistically resulted in higher rice grain contamination with increasing concentration from 0.27 to 0.65 and 0.14–0.40 mg kg−1 for Indica and Japonica rice, respectively. However increase of Cu in brown grain was only attributed to its uptake enhancement under warming. Our study provides a new understanding about the food production insecurity of heavy metal contaminated soil under the future global warming.

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