Vertical distribution of main soil hydroxyanthraquinones in soil profiles

The vertical distribution of main soil hydroxyanthraquinones (HAQs) in the soil profiles of five Japanese Andosols, one Japanese Cambisol, and one Nepalese Cambisol was analysed quantitatively, using high performance liquid chromatography and thin layer chromatography with a two stage development accompanied by scanning densitometry. The vertical distribution patterns of chrysophanol (CPL) and its dimers in Andosols profiles showed maximum contents in the middle part of the surface horizon. The vertical distribution of physcion (PYS) and its dimers in soil profiles showed various patterns in each profile. The vertical distribution of HAQs in Andosols under a Miscanthus sinensis grassland, and in an adjacent successional red pine ( Pinus densiflora ) forest at Sugadaira, Japan, were investigated. In the surface soil (0-15 cm), the contents of the dimers of CPL (microcarpin and chrysotalunin) slightly increased and those of the dimers of PYS (7,7'-biphyscion and hinakurin) showed an increase in the succession, whereas the contents of monomeric HAQs (CPL and PYS) slightly decreased suggesting preferential production of dimeric HAQs below a depth of 15 cm in the forest Andosol. The dimers of CPL and the dimers of PYS exhibited different structures, vertical distribution patterns, and changes in the contents in Andosols in the secondary succession.