[AHW23-P11] A comparative Study on Water Environment of Isolated Islands - Focusing on Islands in Nagasaki Prefecture - (3)
キーワード：壱岐島、対馬、五島列島、平戸諸島、水環境
1. Introduction Research on islands in Nagasaki prefecture has hardly been investigated and research has been promoted since 2014 from Goto Island Islands, Tsushima, Iki, Hirado. For this time, we will clarify the water environment in each area from the relationship with land use and climate, and make it a foothold to clarify the material cycle of each island.
2. Target area Iki is rugged with a maximum altitude of 213 m, and there are numerous reservoirs in various parts of the island. In Tsushima, the altitude of the entire island is relatively high, and the mountains occupy about 89%. The Goto Islands Island consists of about 140 large and small islands, with large geological differences on each island. The Hirado Islands have many mountains while the fields are also relatively large. The population penetration rate of wastewater treatment in both areas is as low as 20-40%.
3. Research method Field survey was conducted 2 to 4 times a year from 2014 after organizing and examining existing research. On the site, water temperature, temperature, electric conductivity (EC), pH and RpH, COD were measured, and water was taken to measure the total organic carbon and the main dissolved components.
4. Results and discussion In Iki, the influence of agriculture appears in EC and TOC, but it is interesting that there is almost no effect of nitric acid. On the other hand, although many nitric acid was detected in the Goto Islands, it is thought that factors are due to paddy fields in Iki and upland fields in Goto Islands. Tsushima showed relatively low concentrations of EC and dissolved components, and seasonal changes also appeared. In Hirado Island, especially in the southern part, the geological influence is large in many places, the impact of sea salt is strong in Ikitsuki island and Azuchi Oshima. EC tends to rise in rainwater from October to March, pH tends to decrease. From the above, it is considered that the difference in the quality of the islands is greatly influenced by the difference of geology, topography and agricultural form.
2. Target area Iki is rugged with a maximum altitude of 213 m, and there are numerous reservoirs in various parts of the island. In Tsushima, the altitude of the entire island is relatively high, and the mountains occupy about 89%. The Goto Islands Island consists of about 140 large and small islands, with large geological differences on each island. The Hirado Islands have many mountains while the fields are also relatively large. The population penetration rate of wastewater treatment in both areas is as low as 20-40%.
3. Research method Field survey was conducted 2 to 4 times a year from 2014 after organizing and examining existing research. On the site, water temperature, temperature, electric conductivity (EC), pH and RpH, COD were measured, and water was taken to measure the total organic carbon and the main dissolved components.
4. Results and discussion In Iki, the influence of agriculture appears in EC and TOC, but it is interesting that there is almost no effect of nitric acid. On the other hand, although many nitric acid was detected in the Goto Islands, it is thought that factors are due to paddy fields in Iki and upland fields in Goto Islands. Tsushima showed relatively low concentrations of EC and dissolved components, and seasonal changes also appeared. In Hirado Island, especially in the southern part, the geological influence is large in many places, the impact of sea salt is strong in Ikitsuki island and Azuchi Oshima. EC tends to rise in rainwater from October to March, pH tends to decrease. From the above, it is considered that the difference in the quality of the islands is greatly influenced by the difference of geology, topography and agricultural form.