RESULT AND DISCUSSION
The degree of seaweed cover on the test plates is shown in Table
. After three months, the surfaces of the test plates were covered in Bacillariophyceae,
arthropod adhesion was confirmed. The condition of the EPOC type plate after one month is shown in Figure
5. After five months, the adhesion of Colpomenia sinuosa
was confirmed on porous concrete. After
one year, the adhesion of Ecklonia cava,
over 40 cm in length, was confirmed on the EPOC plates.
The dominant species after one year was Ecldonia cava
of the brown alga plant.
Figure 5. Condition of the test plate after one month (EPOC)
The degree of seaweed cover on the porous concrete was clearly higher than on normal concrete. The condition of seaweed adhesion on the EPOC plate is shown in Figure 6.
Figure 6. Condition of the test plate after one year (EPOC)
The population of Ecklonia cava on test plates is shown in Figure 7. After two years, the population increased. Also, the population cava on the EPOC plates was clearly higher than on other types.
Figure 7. Relationship between seaweed population and progress period
EPOC has the strength and voids which are necessary as a base for seaweed bed creation. Seaweed rapidly adheres to porous concrete. Seaweed adhesion to porous concrete was found to be greater than was the case with normal concrete. Because of the mixture of granulated fertilizer and converter slag, there tended to be a high degree of seaweed cover. It is concluded that porous concrete with fertilizer is effective as an adherent basis for algae.
The following conclusions have been reached.
1. Employing a special method for treating fertilizer, using a special polymer in the seal, a granulated fertilizer for porous concrete has been developed. It has been confirmed that by using this granulated fertilizer, the elution of the rapid fertilizer component from porous concrete can be prevented and fertilizer elution can be maintained.
2. A mixture with converter slag also becomes a source of elution for ferrous ion.
3. Seaweed rapidly adheres to porous concrete. Seaweed adhesion to porous concrete was found to be greater than with normal concrete.
4. Because of the mixture of granulated fertilizer and converter slag, there tended to be a high degree of seaweed cover and wet weight.
This work was sponsored by the Japan Science and Technology Corporation (JST). A part of the research was supported by a scientific grant No.09480137 of the Japanese Ministry of Education. The authors are pleased to acknowledge the considerable assistance of Dr. W. Kida (Institute of Environmental Geoscience CO., LTD) and Mr. Y. Onoda (Institute of Environmental Geoscience CO., LTD). The authors also wish to express their sincere appreciation to all the principals and engineers who assisted with the data collection for this study by taking the time to complete the survey.
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