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Patterns and rates of deposition, migration and retention of pollutants in man-made strata depend on the depositional history and physical and chemical characteristics of the constituent materials. A sound understanding of the spatial and chronological relationships of materials is required for effective evaluation of solid, liquid and gaseous geo-pollution and design and understanding and interpretation of investigations of potentially contaminated land. Description of materials and boundaries requires clear terminology. A proposed terminology has been developedbased on experience from a variety of sites in Japan including the experimental infilling of an old quarry. The terminology is commended for further discussion.

Lake Kitaura is a shallow lake maximum depth: 7m surrounded by low diluvial uplands and alluvial plains in the eastern Kanto region, central Japan. A northeasterly wind prevails throughout the year except in winter. The steady wind direction is suitable for the study on wind effects in relation to bottom surface sedimentation in Lake Kitaura.Grain size and chemical components of bottom surface sediments are controlled by water movements such as lake currents and wave action Inouchi et al., 1989;Kumon et al., 1993 . The dominant factors for lake water movement may average out the nature and distribution of the bottom sediments. Lake sediments can record sedimentary processes of lakes which reflect past environmental conditions. There are many controlling factors of sedimentary process; however, it is thought that Introduction wave action induced by wind is the principle controlling factor in shallow lakes Sly, 1978. Inouchi et al. 1989 showed the spatial distribution of heavy metals, total carbon and total nitrogen in Lake Kasumigaura, and explained that the distribution was due to reworking and resedimentation by wave and lake current. Inouchi et al. 1989 and Inouchi 1990 also showed the areal distribution pattern of heavy metals, total carbon, total nitrogen and the accumulation rate in Lake Biwa, and put forward a cloud model for deep lake sedimentation. Kumon et al. 1993 studied the grain size distribution of bottom surface sediments in Lake Biwa.They pointed out that the geostrophic gyre may be a primary factor controlling the distribution of bottom sediments in the off-shore zone of Lake Biwa, and advocated that the grain size distribution reflected average movements of lake currents. Chikita 1986 is an example of an earlier study discussing the river inflow effect to lake sed- Characteristics of bottom surface sediments in relation to wind and wave action in Lake Kitaura, central JapanIn order to reveal sedimentary processes in shallow lakes, we collected samples from points in Lake Kitaura-a shallow coastal lagoon in the eastern margin of the Kanto region, central Japan, and analyzed grain size distribution, TOC, TN and C/N ratio. We propose a new depositional model for shallow lakes controlled by wave action owing to wind. The distribution of sandy sediments is restricted to areas near the perimeter of the lake, and correlates with areas of low contents of TOC and TN. Alternatively, clay-rich sediments are most widely distributed, and show high concentrations of TOC and TN. The TOC /TN ratio is low, about to throughout the basin, suggesting that major organic matter originated from planktons in the lake. High TOC/TN ratios over recognized in the northern end of the lake evidently suggests the influence of tributary rivers. The bottom sediments of Lake Kitaura are characterized by a predominance of clayey sediments which cover most of the sublacustrine plain and a narrow zone of sandy sediments along the southern coastal area shallower than . m. The former sediments are transported as suspended matter rew...

Marine organisms, including phyto-and zoo-plankton, macroalgae, and animals, concentrate arsenic in various organic forms. However, the distribution and fate of these organoarsenicals in marine environments remains unclear. In this study, the distribution of organoarsenicals in coastal marine sediment in Otsuchi Bay, Japan, has been determined. Methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, arsenobetaine, arsenocholine and other unidentified arsenic species were detected in marine sediment by high-performance liquid chromatography-inductively coupled plasma mass spectrometry analysis of methanol-water extracts. Arsenobetaine was the dominant organoarsenical at four of the seven stations where tests were carried out, and unidentified species or dimethylarsinic acid dominated at the other stations. Total organoarsenicals (as arsenic) in the surface sediment amounted to 10.6-47.5 µg kg −1 dry sediment. Core analysis revealed that concentrations of organoarsenicals decreased with depth, and they are considered to be degraded within 60 years of deposition. These results show that organoarsenicals formed by marine organisms are delivered to the sediment and can be degraded within several decades.