Narrow Results

Sr is an indicator used in studies on fish migration. In this study, the Sr profiles of ridges, which are growth lines in fish scales, in Sakhalin taimen (Hucho perryi) were examined by micro-PIXE analysis. Sakhalin taimen were reared under freshwater conditions for six months. The ridges that formed during the rearing experiment were subjected to PIXE spot analysis. This analysis was performed in a 5 X 5 μm² area in the center region of each ridge of the scale section, and the Sr levels were calculated using the thin-section standard. The mean Sr concentration in the ridges was 428± 48 μg/g. The quantitative PIXE spot analysis successfully provided Sr profiles for the scale corresponding to ridge formation.

We estimate the effect of changes in water deliveries from large projects on agricultural production. We estimate a region-scale, multi-output production model of the San Joaquin Valley of California using observed historical data. The model incorporates seven crop outputs and the labor input as functions of project water supply, groundwater pumping price, other surface water sources, wages, and crop prices. We find that: (1) reduced irrigation water supply reduces the demand for farm labor and the production of some crops, (2) regional production mix tends to shift towards cotton when water supply is high and (3) some structural change has occurred over the course of our 22 year study period, with production of annual crops becoming more sensitive to changes in project water supply and labor becoming less sensitive to local surface water conditions.