Characteristics of carbonate beach materials in Okinoerabu Island and southern part of Okinawa main island

Carbonate beaches has functions as shore protection and recreation zone to attract many tourists, thus the beaches should be properly sustained. This paper mainly deals with the character for carbonate beach materials such as grain size distribution of carbonate natural beach material and nourished beach material in Okinawa and Okinoerbu islands, because the origin and source of beach sediment should be identified to protect a carbonate beach. The study shows that most of beach material is originated and around a coral reef, thus a coral reef system should be preserved to supply the sediment on the beach

Involvement of Active Oxygen in Lipid Peroxide Radical Reaction of Epidermal Homogenate Following Ultraviolet Light Exposure

To elucidate the radical mechanism of lipid peroxidation induced by ultraviolet light (UV) irradiation, an electron spin resonance (ESR) study was made on epidermal homogenate prepared from albino rat skin. The exposure of the homogenate to UV light resulted in an increase in lipid peroxide content, which was proportional to the time of UV exposure. Using ESR spin trapping (dimethyl-1-pyrroline-N-oxide, DMPO), the DMPO spin adduct spectrum of lipid radicals (L·) was measured following UV exposure (DMPO- L· :aN = 15.5 G, aH ≈ 22.7 G), as was the spectrum of DMPO-hydroxyl radical (DMPO-OH, aN = aH = 15.5 G). In the presence of superoxide dismutase, the DMPO spin adduct spectrum of lipid radicals was found to be reduced remarkably. Therefore, it was shown that the generation of the lipid radicals partially involves superoxide anion radicals, in addition to hydroxyl radicals. In the ESR free-radical experiment, an ESR signal appeared at g = 2.0064 when the ESR tube filled with homogenate was exposed to UV light at-150°C. The temperature-dependent change in the ESR free radical signal of homogenate exposed to UV light was observed at temperatures varying from-150°C to room temperature. By using degassed samples, it was confirmed that oxygen is involved in the formation of the lipid peroxide radicals (LOO·) from the lipid radicals (L·)

Field study of the generation of high speed reef current during winter season

Coral reef and carbonate beach attract many tourists for instance, nearly six million people in Okinawa. However, drowning accidents by a strong offshore current happen every year. Therefore, this paper deals with the physical characteristics of a reef current during winter season at Yoshiwara beach, Ishigakijima, Okinawa Prefecture, Japan, where drowning accidents were occurred by strong reef current during marine leisure activities. Field study on reef current was conducted in November and December, 2006 when northern wind prevailed the study area. The field study shows that the maximum 20-min average offshore velocity could be order of 2 m/s especially during winter season, because the northern wind that is perpendicular to the coast is persistent and generates reasonably high waves