Abstract
Geochemical characteristics of surface (0-10cm) sediments (110 samples) collected from the Fujimae tidal flat, Aichi Prefecture, Japan are studied. Tidal flat sediments (<180μm size fraction) in the northwestern region are enriched in Al2O3, Na2O and CaO, but depleted in Zn and Cr, compared with those in the central and eastern regions. These differences are not attributed to the variation in grain size, but rather to that in compositions of detrital materials. The tidal flat sediments at the central and eastern regions are also characterized by the presence of yellowish-brown surface layers less than 3cm thick, which overlie black inner layers. In general, these surface layers are enriched in P2O5 compared with the inner layers. This may be attributed partly to redistribution of phosphorus from the inner layer to the surface layer and its adsorption on Fe-hydroxide. Calculations of enrichment factors for minor elements show that some heavy metals such as Zn, Cu and Pb are markedly enriched in the sediments.
