Thermal neutron activation analysis was performed on the 200-meter core samples as well as on the bottom surface ones, in order to find out the correlation between the sedimentary environments and the distribution profiles of elements. The elements quantitatively determined were Na, K, Rb, Cs, Ca, Al, Sc, La, Ce, Eu, Th, V, Mn, Cr, Co, Fe, Sb and As. In addition to these, Sr, Ba, Sm, Dy, Tb, Lu, Hf, Ta, W, Au, Hg, U, Cu, Zn, Br, Cl, Se and Te were detected. Their quantification is on the way. The analytical results thus obtained were treated by a computer in order to obtain correlation coefficients among the elements. In addition to this, graphical analysis was also performed on several elements, among which strong correlations were found to conform. As a result, the followings were concluded.
Among the bottom surface samples, pelagic ones contain much more amounts of Mn, Fe, K and As and less amount of Na as compared with coastal ones which show characteristic compositions of places; one of the typical examples is the thorium contents. In the core samples, the post deposital changes in composition were found to exist. The order of survivalability of elements in core samples is ThΔCeΔScΔCr>Fe> Co> Mn. The detailed discussion will be given on this ordering in relation to the redox potentials.

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It has been noticed by recent studies that allochthonous organic matter plays a great role in biological production in a lake, swamp or river.
Lake Tatsu-numa is surrounded by Salix-Pinus vegetation. Transitional processes of the plant debris deposited on the littoral zone are evident in the lake, where the plant debris supply 80% of the primary food source for benthos and stands in considerable trophic relationships.
It was made clear that the plant debris is fed by Glyphotaelius admorsus etc., besides being used for nesting by Neuronia latipennis and Anisocentropus immunis, on the other hand an acceleration of decomposition by fungi or bacteria is also found. It does not take a long time for those micro-organisms, such as bacteria, flagellates, ciliates and nematodes to attach to plant debris after shedding.
The C/N ratios change in parallel with the fragmentation of plant debris, however the C/N ratio of organic suspensions becomes 5 to 10 as a result of the increase of micro-organisms.
The origin of organic suspension in Tatsu-numa comes from the terrestrial plant debris and the algal mat taking a great part in increasing suspended organic seston. Besides it is considered that bacteria or other micro-organisms are involved in the formation of deposited manganese grains obtained from the samples by an EKMAN-BIRGE's bottom sampler.

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Three reservoirs in the Monobe River were surveyed in July 1973, and February and March, of 1974. The rate of water exchange is low in the Nagase Reservoir and high in the other two, the Sugita and Yoshino, both of which have no thermal stratification and have the retention time less than 2 hours.
In July the plankton of the Nagase Reservoir is considerably different from the other two. In the former, Chroococcus limneticus (blue-green alga) and Synedra ulna (diatom) are dominant. In the Sugita and the Yoshino Reservoirs, however, there are found two dominant diatoms, Melosira varians and Cymbella tumida, both of which seem to have been liberated from the flora attached to the upper river bed. The two reservoirs in the lower reaches have no plankton of the lakes themselves, because the mean staying time of water is too short.
In February the plankton of the lower two lakes is the same as that of the upper lake, though Peridinium willei did not occur in the lower two lakes. This dinoflagellida makes the water red in the Nagase Reservoir in March.
Nagase, Sugita, Yoshino Reservoirs were investigated in 1973 in regard to their benthos. Chironomus plumosus, characteristic of eutrophic lakes, was found abundantly on the bottom in the Nagase Reservoir. Cryptochironomus sp. (B) and Phaenopsectra sp. (C), both of which are characteristic species of mesotrophic lakes were found on the bottom in the Sugita and Yoshino Reservoirs.

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Thirteen samples were collected at four stations in the Uji River, Kyoto, during the period from May 1970 to November 1973. The species identified belong to 33 genera and 165 species in total as benthic diatoms. The values of R. F. of those diatoms which are more than 5% of total 20. Those twenty diatoms can be classified according to the three grades of water quality as follows.
Oligosaprobic only : Cymbella tumida, Fragilaria crotonensis, Melosira granulata, M. granulata var. angustissima, M. italica, M. solida and Nitzschia clausi. Both α-oligo and β-mesosaprobic : Cymbella turgidulla, Navvicula cincta, N. cryptocephala and N. cryptocephala var. exilis. Both α-oligo, β- and α-mesosaprobic : Cymbella ventricosa, Gomphonema olivaceum, Nitzschia aciularis and Synedra ulna. β-mesosaprobic : Nitzschia amphibia, N. frustulum and Synedra radians. Both β- and α-mesosaprobic : Synedra rumpens var. familiaris. α-mesosaprobic : Synedra acus.

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1. Lakes Kusshyaro-ko, Akan-ko, Toro-ko and Shikaribetsu-ko were investigated in 1973 in regard to their bottom fauna,
2. In Lake Kusshyaro-ko, only Spaniotoma sp. (B-5) was found in the profundal zone. The dissolved oxygen was rich and the pH value was 4.2 through the layers from the surface to the bottom at the central part of the lake.
3. In Lake Akan-ko, excepting the azoic zone which extends to the bottom deeper than 32 meters, C. plumosus, Sergentia sp. (B-1) and Procladius sp. (F) occurred widely ; C. plumosus the dominant.
4. In Lake Toro-ko, Chaoborus sp. and C. plumosus are distributed widely on almost all over the bottom. The former made up 59.5% and the latter 33.4% of the total bottom fauna.
5. In Lake Shikaribetsu-ko, the macroscopic animals were scarcely found in the zone deeper than 95 meters, where the dissolved oxygen contents were 0.33cc/l. Tubifex sp. occurred abundantly on the bottom shallower than 75 meters, but chironomid larvae were very scanty.

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