Distribution and coordination environment of lanthanum (La) in internodal cells of Chara have been determined by inductively coupled plasma-mass spectrometry and X-ray absorption spectroscopy (XAS). The results indicate that after treatment with 4 μmol•dm－3 LaCl3 solution for 12 h, most of La in cells is located in the cell wall fraction and the bonding is tight. The order of La concentrations in the subcellular fractions is cell wall>>cytoplasm>>vacuole. The results of XAS show that La3＋ is coordinated to 9 oxygen atoms in the cell wall, and the coordination environment is similar to that of lanthanum acetate, which indicates that La bonds to the cell component via carboxylate groups. According to the high ability of La accumulation, Chara can act as a biological indicator or scavenger of rare earth pollution in aqueous solutions.

Key words: lanthanum, rare earth, charophyte alga, X-ray absorption spectroscopy, inductively coupled plasma mass spectrometry