Benthic foraminifera studied

In order to provide AMS analyses to the broad ocean sciences research community, the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) was established at Woods Hole Oceanographic Institution (Massachusetts) in 1989. Studies performed there include identification of sources of carbon-bearing materials in the water column and sediment, dating of sedimentary samples, investigations of paleocirculation patterns (e.g., from observations of differences in 14C relative abundances in planktonic and benthic foraminifera, and coral cores and cross sections), as well as studies of modern oceanic carbon cycling and circulation. In fact, much that is known about advective and diffusive processes in the ocean comes from measurements of chemical tracers, such as 14C, rather than from direct measurements of water mass flow. 

Unfortunately, equations (3.19) and (3.20), although the best currently available for the data, can only be considered tentative. The weakness lies in the temperature dependence. As mentioned earlier, it is not known whether the results reflect a temperature dependence or a change in the proportion of aragonite to calcite. Another shortcoming in this relationship is that the temperature range of the experiments, 20° to 63°C (if Baertschi s data are included), is well above the temperature at which many organisms secrete carbonate. Because benthic foraminifera have proved very useful in carbon isotopic studies, it is important to have carbon isotopic equilibrium defined over their temperature range. 

Grossman E.L. (1984) Carbon isotopic fractionation in live benthic foraminifera -comparison with inorganic precipitate studies. Geochim. Cosmochim. Acta 48, 1505-1512. 

Grossman E. L. (1987) Stable isotopes in modem benthic foraminifera a study of vital effect. J. Foraminiferal Res. 17(1), 48-61. 

Temperature dependence of foraminiferal Mg/ Ca ratios was first reported back in the 1950s (Chave 1954 Blackmon Todd 1959). In recent years there have been various attempts to calibrate this, including culture, sediment trap and core-top approaches that have given consistent results for both planktonic and benthic foraminifera (Fig. 6) thanks to careful studies such as these, foraminiferal Mg/Ca is now emerging as an important temperature proxy. 

Live benthic foraminifera and their stable isotopic composition at sites of active methane discharge have been studied at the Pacific margins (Rathbum et al. 2000 Bernhard et al. 2001 Rathbum et al. 2003 Torres et al. 2003 Herguera et al. 2004 ... 

In a study on the distribution in tests of live and dead benthic foraminifera in surface and subsurface sediments from 16 stations of intermediate water depths along the SW African continental... 

Several expressions have been used to describe the difference between 8 0(calcite) and 8 0(water) (often abbreviated as (8c - 8w)) as a function of temperature (e.g. Shackleton 1974 Erez Luz 1983 Kim O Neil 1997 Bemis et al. 1998). The Shackleton (1974) benthic foraminiferal palaeotemperature equation is based on core-top Uvigerina data, the equations of Erez Luz (1983) and Bemis et al. (1998) are based on laboratory cultured planktic foraminifera, and the equation of Kim O Neil (1997) is based on inorganic precipitation studies. In a study of the isotopic composition of Rose Bengal stained (live, or recently living) core-top benthic foraminifera, McCorkle et al. (1997) used a palaeotemperature equation based on earlier inorganic precipitation studies of O Neil et al. (1969) and Friedman O Neil (1977) ... 

No previous studies have investigated isotopic composition in modem benthic foraminifera from NW Scottish coastal or fjordic environments. This study therefore aims to (1) compare the temporal pattern of calculated equilibrium calcite at sites from NW Scotland (Loch Sunart, Fig. 1) to 8 Oforaui measured from different species of modern and live benthic foraminifera collected from the same sites and (2) comment on potential seasonal effects in the stable oxygen isotopic composition of the tests. 

Seasonal study of delta 0-18 and delta C-13 in living (stained) benthic foraminifera from two Swedish fjords. Marine Micropaleontology, 53, 159-172. 

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