The vertical distributions of the ¹⁴C ¹³⁷CS ²¹⁰Pb, and ²¹⁴Pb concentrations, and of total organic carbon and nitrogen contents, were examined for the 50cm-long cored sediment collected from Lake Biwa(35. 3°N, 136°E, water depth: 70m). The sediment column was divided by 5mm intervals from surface to 10cm depth and by 10mm from 10 to 30cm depth. The ¹⁴C abundance, Δ¹⁴C, was measured by the direct detection of ¹⁴C atoms using a Tandetron accelerator mass spectrometer on acid-insoluble organic carbon extracted from 1.5g of each sediment sample divided vertically. Activities of ¹³⁷Cs, ²¹⁰Pb and ²¹⁴Pb were measured with a well-type pure-germanium detector, and the total organic carbon and nitrogen contents with a C-N corder, using about lg of each sample.
The followings were revealed through the present study:
(1) The sedimentation rate was calculated to be 0.0333±0.002g/cm²/yr(0.152±0.008cm/yr at the surface of the bottom sediment) by the ²¹⁰Pb method. The flux of 210Pb _excessdeposition at the surface of the bottom sediment was 0.45±0.04pCi/cm²/yr; this was about 60% of the annual ²¹⁰Pb deposition from the atmosphere.
(2) The ¹³⁷Cs concentration was widely distributed through the sediment column in comparison with a yearly change of the deposition rate from the atmosphere. The total amount of ¹³⁷Cs deposited in the sediment column was calculated as 2.63pCi/cm²; this was about 65% of the amount of total ¹³⁷Cs deposited so far in Osaka.
(3) Both organic carbon and nitrogen contents of the sediment decreased rapidly with increasing depths and reached constant values around 8-9cm in the depth. On the other hand, the carbon to nitrogen ratio was almost constant (C/N≈10) throughout the sediment column studied.
(4) The Δ¹⁴C value of the sediment increased from-250 to 40‰, with changing depths from 3cm to surface, owing to the addition of the artificially produced ¹⁴C to the atmosphere. The Δ¹⁴C value of the sediment before nuclear tests was about-250‰; this ¹⁴C concentration was 25% lower than that of the atmospheric CO₂ at that time. The increase in the ¹⁴C concentration of the sediment due to the bomb produced ¹⁴C was monotonous, lasting from 1956 to 1980. This change of Δ¹⁴C with time showed a quite different trend from the yearly change of Δ¹⁴C of the atmospheric CO₂, depending probably on the complicated mechanism of accumulating organic materials in the lake sediments.
(5) Radiocarbon dating on organic carbon of Lake Biwa sediments at depths from 3 to 4cm gave the ¹⁴C ages of 2200-2400y BP, which were quite older than the ²¹⁰Pb ages of A. D. 1945-55.

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The Late Pleistocene sands in the Paleo-Tokyo Bay are compositionally rather immature and are very sensitive to the environmental differentiation controlled largely by depositional hydrodynamics.
Fluvial sands contain more lithic fragments and have less quartz and feldspar than shallow marine sands, owing to the combined effects of abrasion, destruction and differentiation of sand grains by nearshore wave and tidal actions. Light minerals of quartz and feldspar are more stable than lithic fragments and were then transported offshoreward by storm-generated waves, accompanied by flood influx. During the offshoreward transport and sedimentation, relative ratio of quartz and feldspar was gradually increased by the differentiation of sand grains. Nearshore sands, on the other hand, are more quartzose and have fewer feldspar than shoreface-offshore sands. Continual wave and tidal actions in the nearshore consequently gave rise to abrasion and destruction of feldspar as well as lithic fragments. The nearshore sands then resulted in the most stable composition in the Paleo-Tokyo Bay.
The nearshore sands, however, were probably generated from two major sources. One is the fluvial sands which were directly derived from provenances of the Paleo-Tokyo Bay sediments. The other is the recycled sediments which were eroded and transported from the older Paleo-Tokyo Bay sediments by waves and longshore currents. The recycling of the Paleo-Tokyo Bay sediments also contributed to the compositional stability of the nearshore sands.

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