Can plants reduce chromium to metallic form ?

Knowledge of Cr redox state in crop plants is fundamental to assess potential Chromium (Cr) toxicity to human beings. XAS is an ideal probe to determine the oxidation state of Cr in plant matrix. We propose to use High Energy Resolution Fluorescence Detected X-ray Absorption Spectroscopy (HERFD-XAS) to characterize the speciation of Cr in plants samples with “natural Cr levels” collected from laboratory experiments. The objective is to fill the gap in fundamental knowledge of the Cr speciation in plants at low but environmentally-relevant range of concentrations. Indeed, it is well known that plant can reduce Cr(VI) to Cr(III), but our preliminary results achieved on a single sample tend to show that plant can also reduce Cr(III) to Cr(0). This result is new and need to be confirmed on a larger set of plant samples.

明确农作物中铬（Chromium, Cr）的氧化还原状态，是评估铬对人体潜在毒性的核心基础。X射线吸收光谱（X-ray Absorption Spectroscopy, XAS）是测定植物基质中铬氧化态的理想表征手段。本研究拟采用高能量分辨荧光探测X射线吸收光谱（High Energy Resolution Fluorescence Detected X-ray Absorption Spectroscopy, HERFD-XAS），对实验室培养获得的「天然铬水平」植物样品中的铬化学形态进行表征。本研究的目标在于填补当前研究空白：即针对低浓度且处于环境相关区间内的铬在植物中的化学形态学基础认知缺口。众所周知，植物可将六价铬[Cr(VI)]还原为三价铬[Cr(III)]，但我们在单一样本中得到的初步结果显示，植物或许还能将三价铬[Cr(III)]还原为零价铬[Cr(0)]。该发现尚属首次，需通过更大规模的植物样本集加以验证。