Trace Elements

Trace Element interactions in the Estuarine Zone of the Anasco River, Puerto Rico

Wolfe D.A., Forster W.O., McClin R., Lowman F.G. The Estuarine Zone of the Anasco River, Puerto Rico. Symposium on the Combined Effects on the Environment of Radioactive Chemical and Thermal Releases... 1977. pp 155-178.

Seasonal changes in sea surface temperature and salinity during the little ice age in the caribbean sea deduced from Mg/Ca and O-18/O-16 ratios in corals

Watanabe, T., A. Winter, and T. Oba. 2001. Seasonal changes in sea surface temperature and salinity during the little ice age in the caribbean sea deduced from Mg/Ca and O-18/O-16 ratios in corals. Marine Geology 173 (1-4) (MAR 15): 21-35.

The oxygen isotropic composition (delta 18O) of coral skeletons reflects a combination of sea surface temperature (SST) and the delta 18O of seawater, which is related to sea surface salinity (SSS). In contrast, the magnesium/Calcium (Mg/Ca) ratio of a coral skeleton reflects SST independent of Salinity. by using the relationships among coral Mg/Ca ratios, coral delta 18), seawater delta 18O and SST, it is possible to determine past SST and SS uniquely. Such determinations were made and calibrated using the Mg/Ca ratio and the delta 18O of the modern part of a 3 m long coral core (Monastrea faveolata) collected from the southwest coast of Puerto Rico in the Caribbean Sea where both SST and SSS changes seasonally and the seawater delta 18O measured at the coral site....


Moyer RP (2008) Carbon Isotopes (δ13C & Δ14C) and Trace Elements (Ba, Mn, Y) in Small Mountainous Rivers and Coastal Coral Skeletons in Puerto Rico. Ph.D. Dissertation, The Ohio State University, School of Earth Sciences, Columbus, OH. 260pp.

Tropical small mountainous rivers (SMRs) may transport up to 33% of the total carbon (C) delivered to the oceans. However, these fluxes are poorly quantified and historical records of land-ocean carbon delivery are rare. Corals have the potential to provide such records in the tropics because they are long-lived, draw on dissolved inorganic carbon (DIC) for calcification, and isotopic variations within their skeletons are useful proxies of palaeoceanographic variability. The ability to quantify riverine C inputs to the coastal ocean and understand how they have changed through time is critical to understanding global carbon budgets in the context of modern climate change. A seasonal dual isotope (13C & 14C) characterization of the three major C pools in two SMRs and their adjacent coastal waters within Puerto Rico was conducted in order to understand the isotope signature of DIC being delivered to the coastal oceans. Additionally a 56-year record of paired coral skeletal C isotopes (δ13C & Δ14C) and trace elements (Ba/Ca, Mn/Ca, Y/Ca) is presented from a coral growing ~1 km from the mouth of an SMR. Four major findings were observed: 1) Riverine DIC was more depleted in δ13C and Δ14C than seawater DIC, 2) the correlation of δ13C and Δ14C was the same in both coral skeleton and the DIC of the river and coastal waters, 3) Coral δ13C and Ba/Ca were annually coherent with river discharge, and 4) increases in coral Ba/Ca were synchronous with the iii timing of depletions of both δ13C and Δ14C in the coral skeleton and increases in river discharge. This study represents a first-order comprehensive C isotope analysis of major C pools being transported to the coastal ocean via tropical SMRs. The strong coherence between river discharge and coral δ13C and Ba/Ca, and the concurrent timing of increases in Ba/Ca with decreases in δ13C and Δ14C suggest that river discharge is simultaneously recorded by multiple geochemical records. Based on these findings, the development of coral-based proxies for the history of land-ocean carbon flux would be invaluable to understanding the role of tropical land-ocean carbon fluxes in the context of global climate change.
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