The uptake and speciation of various Al species in the Brassica rapa pekinensis

An investigation was carried out on the uptake and speciation of Al species in Al tolerant Chinese cabbage (Brassica rapa L. ssp. pekinensis). Plants were exposed to 10 μg cm−3 of Al in the chemical forms of Al3+, Al-citrate and Al-malate in a time span from 1 up to 24 h. In each experiment the nutrient solution and stem sap were analysed by a combination of FPLC–ICP–AES and ES–MS–MS techniques. Speciation analysis enabled determination of particular chemical forms of Al present in the nutrient solution or in stem sap. The results indicate that Al3+ added to the nutrient solution remained as Al3+ in the solution during the experiments, but in the roots transformation to Al-malate occurred. Al was transported from roots to the upper parts of the plant as Al-malate (70%) and Al3+ (30%). Al-citrate or Al-malate added to the nutrient solution were transferred to the upper parts of the plant without transformation of their chemical forms.