Great Barrier Reef Coral and Halimeda Cd/Ca Ratios: Holocene Paleochemical Records

钙的配给将在珊瑚和文石中确定。将绿藻Halimeda存放在全新世珊瑚礁和澳大利亚大堡礁的生物礁中。其目的是：(1)确定外陆架珊瑚礁中全新世Cd/Ca比值的变化，包括从礁初8500yBP到现在的记录，代表个别珊瑚礁和跨越一定纬度的珊瑚礁背风到迎风环境的岩芯记录；(2)确定全新世大堡礁珊瑚Cd/Ca比值的季节性变化，比较当代和选定的历史珊瑚：(3)确定大堡礁Halimeda生物礁从开始(同纬度珊瑚礁开始前.2000年前)到现在的全新世Cd/Ca比值的变化；以及(4)解释珊瑚和哈里米达的Cd/Ca记录，以检验有关改变营养供应在控制大堡礁全新世珊瑚礁和生物礁生长中的作用的假说。将认真注意识别和分离由于陆地而不是海洋影响而产生的微量元素信号，并注意到蚀变。用石墨炉和火焰原子吸收光谱法测定Cd/Ca、Mn/Ca、Sr/Ca和Mg/Ca比值，用X射线衍射法测定矿物学。

Cadmium.to.calcium rations will be determined in corals and in the aragonite.depositing green alga Halimeda in Holocene reefs and bioherms from the Great Barrier Reef, Australia. The objectives are: (1) to determine Holocene variations in Cd/Ca ratios in outer shelf coral reefs, including records from reef initiation 8500 ybp to the present in cores representing leeward to windward environments in individual reefs and from reefs spanning a range of latitudes; (2) to determine variations in seasonality in Cd/Ca ratios in Holocene Great Barrier Reef corals, comparing contemporary and selected historical corals; (3) to determine Holocene variations in Cd/Ca ratios in Great Barrier Reef Halimeda bioherms, from initiation (.2000 y before coral reef initiation in the same latitude) to the present; and (4) to interpret Cd/Ca records from coral and Halimeda to test hypotheses about the role of changing nutrient supply in controlling Holocene reef and bioherm growth in the Great Barrier Reef. Careful attention will be given to identifying and isolating trace element signals due to terrestrial, rather than oceanographic influences, and to alteration. Graphite furnace and flame atomic absorption spectrophotometry will be used to determine Cd/Ca, Mn/Ca, Sr/Ca, and Mg/Ca ratios; X.ray diffraction spectroscopy will be used to determine mineralogy.