A soil incubation and short-term root growth experiment was conducted to investigate the effects of organic matter application on AI toxicity alleviation in a highly weathered acid soil. Ground leaves of a tree legume (Calliandra calothyrsus Meissn.), ground barley (Hordeum vulgare L.) straw, or CaCO 3 were mixed at various rates with A-horizon soil of a red podzolic soil (Epiaquic Haplustult) and incubated at 90% of field capacity for 4 or 10 weeks. After the incubation, a short term (48 h) root growth test was conducted using mung bean (Vigna radiata (L.) Wilczek), followed by the analysis of the solution and solid phases of the post-harvest soil.Adding either CaCO 3 or organic matter increased root length in mung bean largely by decreasing the activity of monomeric AI in the soil solution. With organic matter, the major mechanisms of this decrease were presumed to be precipitation of soluble AI and the formation of Al-organic matter complexes. The former effect was predicted from the pH increase accompanying the organic matter addition, the increase being larger with legume leaves which had the higher exchangeable and soluble Ca and Mg contents. The concentration of A1 complexed with soluble organic matter also was shown to increase with increasing rate of organic matter addition, the effect again being larger with legume leaves.The sum of monomeric AI species activity and A13+ ~ctivity was negatively correlated with relative root length for the organic matter and CaCO 3 treatments. However, indices which took into account the possible alleviation effects of basic cations in soil solution on A1 toxicity provided an improvement in correlation with relative root length.The efficiency of the two organic amendments relative to CaCO 3 in decreasing A1 toxicity was assessed by comparing the rates required to reduce A13+ activity below 10/xM, the value found to be associated with 90% relative root length for mung bean. The rates of CaCO3, legume leaf and barley straw required to reach this critical value were 0.75, 14, and 42 t ha -1 respectively.

More and more use of coastal areas for waste disposal has recently been expected because land-based disposal facilities have faced acute decrease of remaining capacity and large-scale facilitiesare possible only at coastal areas. While environmental consideration requires sever structural safety for the facilities to protect ambient area from contamination. This study quantitatively investigates sealing performance of embedded steel-plate cell as bulkhead for waste disposal by experiments and three-dimensionalseepage flow analysis. Joint between cells is focused.

In accordance with the test results of the hydraulic model test of the embedded steel plate cell breakwater performed before, it has seemed to be apparent that, this method has the prominent superior characteristic such as less reflectivity and much permeability. However, this test was just conducted at the one local seaport named Shimotsu, in Wakayama prefecture, it would be difficult to apply its test results to the other seaports in Japan equally. Thus, in order to establish the design method of the embedded steel plate cell breakwater to apply all the seaports in Japan generally, several additional experimental test have been repeated. Judging from the above tests results, we could acquire the primary proposed formula such as reflectivity ratio, transmission ratio, the velocity flown the cell interfaces, wave force affecting to the cells and vertical wall, etc., and finally we have obtained the basic knowledge for the establishment of the designing method of the embedded steel plate cell breakwater.

No abstract