Abstract:To analyse suspended sediment sources in unmanaged Japanese cypress plantation watersheds, field measurements and fingerprinting of the suspended sediment was conducted in the Shimanto River basin in southern Japan. For sediment fingerprinting, 137 Cs and 210 Pb ex were detected by means of gamma-ray spectrometry in the surface soil of the forest floor, stream bank and truck trail and mobilized sediment by interrill erosion. The 137 Cs and 210 Pb ex activities associated with the forest floor materials were considerably higher than those of the stream bank and truck trail. The 137 Cs and 210 Pb ex activities associated with the suspended sediment were found to vary with the sampling period. Evidently, the suspended sediment can comprise materials generated from the forest floor by interrill erosion and those from the truck trail and/or stream bank. The multivariate sediment-mixing model using 137 Cs and 210 Pb ex showed that the contribution of the forest floor varied periodically, ranging from 23-56% in the Hinoki 156 subwatershed and from 18-85% in the Hinoki 155 subwatershed. The difference in the average contribution of the forest floor between Hinoki 156 (46%) and Hinoki 155 (69%) may relate to the presence of truck trail networks in the watershed. The truck trail network can play roles of sediment source and pathway for sediment from forest floor to stream channel due to the concentrated overland flow on the truck trail during heavy rainfall events. These results indicate that the forest floor should be recognized as a major source of suspended sediment in unmanaged Japanese cypress plantation watersheds.

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To 1.5 g of y-alumina particles in 40 ml of water was added 10 ml of ammoniacal solution containing 1.5 mg of dithizone and 100 mg of sodium dodecyl sulfate. The solution was acidified to pH 2 to form the surfactant aggregates on the alumina surfaces, into which dithizone was trapped. Traces of copper(II) and silver(I) in water were completely collected on the dithizone-coated alumina over a wide range of pH 1-7; cadmium(II), cobalt(II), nickel(II), lead(II) and zinc(II) were simultaneously recovered at pH 3 -7. The chelating sorbent functioned well even in aqueous solutions containing a large amount of matrix element. The proposed sorption method has been successfully applied to the determination of traces of copper in lead metal.

Forest areas have been identified as important sources of nonpoint pollution in Japan. The managers must estimate stormwater quality and quantities from forested watersheds to develop effective management strategies. Therefore, stormwater runoff loads and concentrations of 10 constituents (total suspended solids, dissolved organic carbon, PO(4)-P, dissolved total phosphorus, total phosphorus, NH(4)-N, NO(2)-N, NO(3)-N, dissolved total nitrogen, and total nitrogen) for 72 events across five regions (Aichi, Kochi, Mie, Nagano, and Tokyo) were characterised. Most loads were significantly and positively correlated with stormwater variables (total event rainfall, event duration, and rainfall intensity), but most discharge-weighted event concentrations (DWECs) showed negative correlations with rainfall intensity. Mean water quality concentration during baseflow was correlated significantly with storm concentrations (r=0.41-0.77). Although all pollutant load equations showed high coefficients of determination (R(2)=0.55-0.80), no models predicted well pollutant concentrations, except those for the three N constituents (R(2)=0.59-0.67). Linear regressions to estimate stormwater concentrations and loads were greatly improved by regional grouping. The lower prediction capability of the concentration models for Mie, compared with the other four regions, indicated that other watershed or storm characteristics should be included in the prediction models. Significant differences among regions were found more frequently in concentrations than in loads for all constituents. Since baseflow conditions implied available pollutant sources for stormwater, the similar spatial characteristics of pollutant concentrations between baseflow and stormflow conditions were an important control for stormwater quality.

Glutamine synthetase (GS) is involved in an accessory pathway of ammonia removal in mammals. To develop a bioartificial liver with a human cell line, GS gene was transfected into HepG2 cells, which had no ammonia removal activity. After culturing in the presence of methionine sulfoximine (MSX), a GS inhibitor, we obtained a MSX-resistant HepG2 subline (GS-HepG2), which had amplified GS gene; ammonia removal activity was estimated to be 1/7 of that of rat primary culture hepatocytes. The cells were cultured in a circulatory flow bioreactor for 109 days, while they multiplied from 5 x 10(7) to 4 x 10(9) cells. Three days after inoculation, the ammonia level of the culture medium was lowered to a level maintained thereafter, suggesting that using recombinant cell lines for bioartificial livers enables long-term repeated treatment for hepatic failure patient. Judging from the rate of decrease in the amount of the added ammonia, the ammonia removal capability of 4 x 10(9) GS-HepG2 cells was almost equivalent to 5 x 10(8) porcine hepatocytes inoculated into the circulatory flow bioreactor. Apart from their ammonia removal activity, GS-HepG2 cells eliminated human tumor necrosis factor-alpha (TNF-alpha). Cytokine removal therefore promises to be another useful property of bioreactor cells.