In order to study the influence of cloud water deposition to forest canopies on the soil solution chemistry and the acidification of forested soil, measurements of both throughfall and soil solution were carried out for two years in seven Cryptomeria stands at the altitude from 240 m to 845 m of Mt.Rokko in Kobe. Cloud water deposition to Cryptomeria stands, which increased with the altitude was 1514 mm at the altitude of 845 m, which corresponded to 127 % of the annual rainfall amount, and throughfall pH at this point was 4.10. Soil pH at the altitude from 835 m to 845 m was from 4.4 to 4.7 and the exchangeable Ca²⁺ concentration was from 0.51 to 0.61 meal 100 g. Annual averages of H⁺ and T.AI concentrations in soil solution at the altitude of 845 m were 0.079 meq/l (pH 4.11) and 0.175 mM, respectively. These concentrations at Mt.Rokko were more than any literature values reported for Cryptomeria stand. As a significant correlation was found between acid deposition through cloud water and H⁺ and T.Al concentration in soil solution, it was suggested that cloud water deposition strongly participated in the soil acidification and the dissolution of aluminum from soil. From comparison of the chemical compositions in throughfall and soil solution, it was shown that throughfall was scarcely neutralized in the soil ecosystem at the altitude of 845 m where acidic cloud water highly deposited. It was supported by lower concentration of exchangeable basic cation in the soil. Significant correlations between Ca²⁺ and NO₃^- concentration in soil solution were found in the seven stands at Mt.Rokko. Since the equivalent ratio of Δ Ca²⁺/Δ NO₃^- in soil solution decreased with increasing H⁺ concentration in soil solution and with decreasing exchangeable basic cation concentration in soil, the ratio was suggested to be an index of the soil acidification. These results indicate that monitoring of both cloud water deposition and soil solution chemistry is essential in the forest ecosystem at the mountainous region.

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A lake basin management system using a GIS was made in Tsukuba, Tsuchiura, and Ami Cities, in Lake Kasumigaura basin. The area of these three cities was divided into 2, 733 unit areas and rearranged in 75 small basins based on geographic characteristics. The water quality was predicted in each small basin from estimated loadings and water volumes using unit-loading method. The predicted and observed quality of effluent water was compared in 20 of these small basins. Observations were carried out four times in 1999 and 2000 at the outflow site of each small basin. The results showed a large difference between predicted and observed water quality. Then, We modified usualunit-loading method about below points. 1. The amount of nutrient including irrigation water into paddy field was counted in total nutrient loadings. 2. The load of total nitrogen (TN) from rainfall adds on upland field. 3. The load from Non-point sources changed to calculation based on L-Q curve. As a result of change, The observed concentrations of chemical oxygen demand (COD), TN and total phosphorus (TP) ranged from 0.5 to 1.0 times the estimated concentrations. For the above results, it was evident that modified unit-loading method based on GIS technique was useful for estimation of nutrient loadings in divided lake basins.

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The Miyako River is the second-class river flowing through Chiba City located in Chiba Prefecture. The middle reaches of the river were formerly natural with a meandering course, rapids, and pools. However, the rise of the water level due to rain has caused damage to the agricultural land around the river. River improvements weremade from late November to mid-December of 1996 as flood countermeasures. The river was widened, straightened, and dredged between Sukezaemon Bridge and Kitayatu Brige. The modifications of depth and shapes of the river had effects on the aquatic plants and water quality. We investigated the influence of the river improvements on the river environment, such as the growth of aquatic plants and water quality. In regard to the vegetation cover area of submerged plants, the area of Potamogeton oxyphyllus decreased after the improvement. The cover area of PP crispus didn't change after improvement. However, the distribution of PP crispus moved from the rapids to the edge of a river after the river improvement. In regard to the vegetation cover areas of emergent plants, the areas of Phalaris arundinacea and Persicaria thunbergii decreased after the improvement. The cover area of Zizania latifolia didn't change. As for the relations between the aquatic plants and the amount of rainfall, the area of PP oxyphyllus decreased with the increase in rainfall both before and after the river improvement. The area of Z latifolia, P. undinacea, P. thunbergii also decreased with the increase in rainfall after the river improvement.

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Precipitation was collected every 24h at Mt.Happo with an automatic wet-only collector; concentrations of inorganic ionic components and dissolved trace metals (Fe, Mn, Al, Pb, Cu and Zn) were measured. The elution of metals such as Zn, Fe, and Cu from the collector was observed, whereas concentration levels of Al, Pb and Mn were low. Preservation tests of metals in rainwater samples stored in polypropylene bottles showed little variation in concentrations of Zn, Mn and Pb. In contrast, Fe, Cu and AI concentrations tended to increase or decrease. Median concentrations of Mn and Pb in precipitation at Mt.Happo in 1996, which had preservation stability and low elution from the collector, were 1.7μg/L for Mn and 1.6μg/L for Pb. The concentration of Mn was strongly correlated with that of Ca²⁺(r =0.95) and increased in the spring, especially during yellow-sand events. The concentration of Pb was highly correlated with that of non-sea-salt (nss)-SO₄^2- in the winter (r = 0.97).

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