Calcification and growth processes in planktonic foraminifera complicate the use of B/Ca and U/Ca as carbonate chemistry proxies
نویسندگان
چکیده
The Open University's repository of research publications and other research outputs Calcification and growth processes in planktonic foraminifera complicate the use of B/Ca and U/Ca as carbonate chemistry proxies Journal Article (2016). Calcification and growth processes in planktonic foraminifera complicate the use of B/Ca and U/Ca as carbonate chemistry proxies. Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyright owners. For more information on Open Research Online's data policy on reuse of materials please consult the policies page. Calcification and growth processes in planktonic foraminifera complicate the use of B/Ca and U/Ca as carbonate chemistry proxies a r t i c l e i n f o a b s t r a c t Keywords: planktonic foraminifera boron uranium proxy sediment trap Although boron and uranium to calcium ratios (B/Ca, U/Ca) in planktonic foraminifera have recently received much attention as potential proxies for ocean carbonate chemistry, the extent of a carbonate chemistry control on these ratios remains contentious. Here, we use biweekly sediment trap samples collected from the subtropical North Atlantic in combination with measured oceanographic data from the same location to evaluate the dominant oceanographic controls on B/Ca and U/Ca in three depth-stratified species of planktonic foraminifera. We also test the control of biological, growth-related, processes on planktonic foraminiferal B and U incorporation by using foraminifer test area density (µg/µm 2) (a monitor of test thickness) and test size from the same samples. B/Ca and U/Ca show little or no significant correlation with carbonate system parameters both within this study and in comparison with other published works. We provide the first evidence for a strong positive relationship between area density (test thickness) and B/Ca, and reveal that this is consistent in all species studied, suggesting a likely role for calcification in controlling boron partitioning into foraminiferal calcite. This finding is consistent with previous observations of less efficient discrimination against trace element 'impurities' (such as B), at higher calcification rates. We observe little or no dependency of B/Ca on test size. In marked contrast, we find that U/Ca displays a strong species-specific dependency on test size in all species, but no relationship with test thickness, implicating some other biological control (possibly related to growth), rather than a calcification control, on U incorporation into foraminiferal calcite. Our results caution against the use of B/Ca and U/Ca in planktonic foraminifera as …
منابع مشابه
Mg/Ca, Sr/Ca, and stable-isotope (DO and DC) ratio profiles from the fan mussel Pinna nobilis: Seasonal records and temperature relationships
[1] We present new annually resolved dO, dC, Mg/Ca, and Sr/Ca ratio records for two shells of the fast growing Mediterranean fan mussel Pinna nobilis, collected from proximal Spanish coast sea grass meadows. The relationship between the potential geochemical proxies and ontogenetic and environmental controlling factors is investigated. Specifically, the use of shell Mg/Ca and Sr/Ca ratios as po...
متن کاملImpact of seawater pCO2 on calcification and Mg/Ca and Sr/Ca ratios in benthic foraminifera calcite: results from culturing experiments with Ammonia tepida
Evidence of increasing concentrations of dissolved carbon dioxide, especially in the surface ocean and its associated impacts on calcifying organisms, is accumulating. Among these organisms, benthic and planktonic foraminifera are responsible for a large amount of the globally precipitated calcium carbonate. Hence, their response to an acidifying ocean may have important consequences for future...
متن کاملPII S 0016 - 7037 ( 01 ) 00852 - 3 Comparison of two potential strategies of planktonic foraminifera for house building : Mg 2 or H removal ?
Marine organisms must possess strategies enabling them to initiate calcite precipitation despite the unfavorable conditions for inorganic precipitation in surface seawater. These strategies are poorly understood. Here we compare two potential strategies of marine calcifyers to manipulate seawater chemistry in order to initiate calcite precipitation: Removal of Mg and H ions from seawater soluti...
متن کاملCalcium isotopic composition of high-latitude proxy carrier Neogloboquadrina pachyderma (sin.)
The accurate reconstruction of sea surface temperature (SST) history in climate-sensitive regions (e.g. tropical and polar oceans) became a challenging task in palaeoceanographic research. Biogenic shell carbonate SST proxies successfully developed for tropical regions often fail in cool water environments. Their major regional shortcomings and the cryptic diversity now found within the major h...
متن کاملSulfate in Foraminiferal Calcium Carbonate : Investigating a Potential Proxy for Sea Water Carbonate Ion Concentration
The sulfur content of planktonic and benthic foraminifera was measured in specimens recovered from deep-sea sediment cores and individuals grown in culture. A new method for measuring sulfur in foraminiferal calcium carbonate was developed, employing a high-resolution inductively coupled plasma-mass spectrometer. The sulfur measurements, expressed as sulfur-to-calcium (S/Ca) ratios in the foram...
متن کامل