¹Dept. of Oceanic Architecture and Engineering, Nihon University

Funabashi, Chiba, JAPAN

okamoto@ocean.cst.nihon-u.ac.jp

　

²CELLS Coastal Environmental Lab.

Numazu, Shizuoka, JAPAN

　

　

Fishery resources in the world are decreasing year by year. The reasons are over-catching, change of habitable environments caused by pollution, and global environmental change. As a result, seaweed communities that support marine ecosystems are especially decreasing in the ocean. Algae enhancement technology is, therefore, the most important thing to improve the living environment of the seaweed communities. Ferrous sulfate is the micronutrient element considered essential to all algae. Ferrous sulfate is used is an industrial waste, which comes from processing titanium ore, and it is very expensive. Slag, used as a core material, is also a waste material for steel works. Our point is to use ocean fertilizer technology, especially a throwing type of iron fertilizer. It becomes harmless that this type of iron fertilizer had transferred the basic behavior of the slag with ferrous sulfate. Our object is to apply algae enhancement technology to real ocean zone by using this throwing type of iron fertilizer. In this paper, the application used by this fertilizer will be introduced and discussed.

　

　

We have so many coastal zone developments now. Faster these developments, especially in Japan have executed, considered not ocean environment but mainly the economy and the efficiency. We also have problems with ocean pollution caused by too much of land-living draining from rivers in Japan. As a result of these problems seaweed communities have been decreasing yearly. The seaweed community in Japan had lost 6,500(ha) for fifteen years. Here, seaweed communities have a function, which supports marine ecosystems, and have a water purification quality. Therefore, creating or improving seaweed communities is very important.

　

Moreover, problems on industrial waste, at the present time in Japan, are caused by very few final-disposal facilities, high cost and high environmental load by not appropriate disposal of waste including toxic substances, so that re-usage of industrial waste is needed. For the purpose of re-usage of industrial waste, ferrous sulfate and also steel slag were selected. These are produced as a waste by titanium oxide or iron manufacture. The main components of this iron fertilizer are ferrous sulfate and slag.

　

Here, iron is micronutrient element for all seaweeds and also plankton (Takeda, 1996). For improving or creating seaweed communities, we have to check the effects. That is, if the iron fertilizer accelerates the growth of seaweed. Our object of this research is to apply algae enhancement technology by using iron fertilizer in the real ocean.

　

　

The usual type of iron fertilizer, including ferrous sulfate is almost paint type, which had already been developed by two of the authors (Hotta, Suzuki et al., 2000), and shown in Photo 1. We used a new type of iron fertilizer in this research. Since this new type is solid and small it is easy to use. We put it on or threw it to use (Photo 2).

　

The iron fertilizer on the right side of Photo 2 consists of ferrous sulfate, sea salt and calcium carbonate (Hotta and Suzuki, 2000), and the left side of Photo 2 consists of ferrous sulfate, slag and diatomaceous. We had carried out two experiments. In experiment 1 in the test tank, the effects had been checked on growth of spore of seaweed. In experiment 2 in the real ocean, the effects had been also checked on the growth of the organism of seaweed.