Fundamental Studies on Ecological Characteristics and Environmental Management of Coastal Ecotones

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(1) The carbon isotope ratio (delta^<13>C) in particulate organic matter (POM) at the Tamagawa River estuary ranged from -30* o -17*. The wide range of delta^<13>C is interpreted by mixing of land-derived organics with phytoplankton. Lower photosynthetic activity of surface phytoplankton in summer in Tokyo Bay was suggested to be due to sudden change of dissolved inorganic nitrogen composition and nitrogen deficiency relative to phosphate and silicate.(2) In eutrophic shallow Lake Kasumigaura, the accumulation of large amount of nitrate in lake water, which has been observed during October to March since 1977, did not occur in 1994-1995, though there were no significant changes in lake environment except the transition of Microcystis bloom to Oscillatoria from 1991.(3) In northern and southern basins of Lake Biwa, dynamics of plankton communities were greatly affected by nitrogen cycling through microbial food webs and wind-induced sporadic supply of phosphorus from deeper layrs.(4) Sa … More go palms growing on the lowland along southeast Asian coastal areas accumulate starch in their tunks. It takes 10-13 years on tropical peat soils and 8-10 years on alluvial soils until maturing. The preliminary input and output budget study showed that copper tended to accumulate while zinc to be lost from peat soils under sago palm cultivat ion. Field experiments from 1983 to 1994 suggested that the underlaying of lime gravels 20 cm below the ground was significantly and sustainably effective in improving surface soil acidity and in increasing lowland rice and upland maize yields.(5) The concept of mitigation was shown to include the creation of favorable environment as well as the wise and proper use and management of various resources in addition to the environmental conservation and restoration. The major consideration in determining what is proper is the capability for use as determined by inherent nature of each ecological system. The process of striking is a balance between improving well-being of people and causing undesirable environmental change. To enhance rational environmental management, a new micro-accounting framework called "environmental resource management accounting" was proposed and its use was illustrated in terms of numerical simulations. Less