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 Nep alese Cambisol was analyzed quantitatively, using high performance liquid c hromatography and thin layer chromatography with a two stage development ac companied by scanning densitometry. The results were as follows: The vertic al distribution patterns of chrysophanol (CPL) and its dimers in Andosols p rofiles 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. Additionally, we investigated the vertical distribution of HAQs in Andosols under a Miscanthus sinensis gras sland, and in an adjacent successional red pine (Pinus densiflora) forest a t Sugadaira, Central Japan. In the surface soil (0-15 cm), the contents of the dimers of CPL (microcarpin and chrysotalunin) slightly increased and th ose of the dimers of PYS (7,7'-biphyscion and hinakurin) showed a remarkabl e increase in the succession, whereas the contents of monomeric HAQs (CPL a nd PYS) slightly decreased suggesting preferential production of dimeric HA Qs below a depth of 15 cm in the forest Andosol. The dimers of CPL and the dimers of PYS exhibited different structures, vertical distribution pattern s, and changes in the contents in Andosols in the secondary succession. The refore, it was assumed that dimeric reaction processes of CPL may be differ ent from those of PYS, if dimeric reactions had occurred in soil.