Carbonate Beach Sand of Abaiang Atoll, Kiribati: Geochemistry, Biogenic Sources, and Properties

摘要: Sandy beaches are critical resources for low-lying Pacific atoll communities, providing protection during storms, and land area many coastal villages. Information on the nature of beach sediment, its geochemistry composition, can help to establish priorities effectively protect sources island sediment. To understand sand sources, this study evaluated physical characteristics including grain-size, from windward leeward profiles around Abaiang Atoll, Kiribati. Beach was >99% carbonate, averaging 37% coral fragments, 30% mollusc shells, 12% foraminifera, 20% calcareous algae. Significant differences were found between reef lagoonal sites in proportions fragments foraminifera tests, with lagoon having higher lower relative beaches. This is attributed high foraminiferal productivity offshore beaches, taphonomic durability longshore drift into lagoon. Mean sediment diameter increased upper at all sites, but fine lacking, dissolution by rainfall groundwater outflow. Geochemical analysis showed a mean 84% Ca-Mg carbonates, which 80% calcium carbonate. There no significant difference percentage or carbonate composition sources. Magnesium magnesium content significantly foraminifera. Sediment-producing near shore habitats village through provision sand, shows need better conserve manage reefs such as seagrass beds, ensure continued supply.