Lead, iron, and organic acid concentrations were determined in low-volume xylem sap samples of cucumbers grown in both "lead-free" and lead-contaminated nutrient solutions containing either Fe-citrate or Fe-EDTA by total reflection X-ray fluorescence spectrometry (iron and lead), graphite furnace atomic absorption spectrometry (lead), and reversed-phase high-performance liquid chromatography (organic acids). Three acids of the Krebs cycle - citric, fumaric, and malic acids - were detected and measured. In presence of Fe-citrate the lead contamination results in about three times higher organic acid production in the cucumber compared with the uncontaminated plants. At the same time the amount of transported iron decreases with about 20%. In presence of Fe-EDTA, the same amount of lead leads to a small change in organic acid production; however, the uptake and the transport processes of iron are considerably hindered (∼35%). Lead transport in the xylem channel was more than one order of magnitude higher when iron was added to the nutrient solution as citrate instead of EDTA complex. These phenomena can be attributed to the participation of the organic acids in the translocation processes of the metals investigated.
ASJC Scopus subject areas
- Analytical Chemistry