Heavy metal incorporation in foraminiferal calcite: results from multi-element enrichment culture experiments with <i>Ammonia tepida</i>

Abstract

Abstract. The incorporation of heavy metals into carbonate tests of the shallow water benthic foraminifer Ammonia tepida was investigated under controlled laboratory conditions. Temperature, salinity, and pH of the culture solutions were kept constant throughout the duration of this experiment, while trace metal concentrations were varied. Concentrations of Ni, Cu, and Mn were set 5-, 10-, and 20 times higher than levels found in natural North Sea water; for reference, a control experiment with pure filtered natural North Sea water was also analysed. The concentrations of Cu and Ni from newly grown chambers were determined by means of both µ-synchrotron XRF and Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA-ICP-MS). The results of both independent analytical techniques agreed within the analytical uncertainty. In general, the concentration of the analysed elements in the tests increased in line with their concentration in the culture solutions. Potential toxic and/or chemical competition effects might have resulted in the decreased incorporation of Ni and Cu into the calcite of the specimens exposed to the highest elemental concentrations. Mn incorporation exhibited large variability in the experiment with the 20-fold increased element concentrations, potentially due to antagonistic effects with Cu. The partition coefficients of Cu and Ni were calculated to be 0.14 ± 0.02 and 1.0 ± 0.5, respectively, whereas the partition coefficient of Mn was estimated to be least 2.4. These partition coefficients now open the way for reconstructing past concentrations for these elements in sea water.

A comparison of benthic foraminiferal Mn / Ca and sedimentary Mn / Al as proxies of relative bottom-water oxygenation in the low-latitude NE Atlantic upwelling system

“…Mn / Ca signatures of the ambient bottom water are recorded by benthic foraminifera. For example, culture experiments have confirmed that the species Ammonia tepida incorporates Mn into the test proportional to the concentration in the ambient water masses (Munsel et al, 2010). Thus, during benthic foraminiferal calcification under hypoxic conditions, more Mn will be assimilated into their calcite tests, whereas under anoxic conditions, or oxic conditions in particular, Mn is expected to decrease, albeit to different amounts (Pena et al, 2005).…”

“…Recent culturing experiments on benthic foraminifera demonstrate that calcification can occur even under anoxic conditions (Nardelli et al, 2014). This is key for the discussion of trace-elemental data derived from the foraminiferal tests, as not only does the timing of the calcification determine the geochemical signature, but it also shows that the signature is recorded in a wide range of oxygen conditions.…”

“…Therefore, under low-oxygen conditions, foraminiferal Mn / Ca is expected to be higher during hypoxic conditions than during anoxic conditions, but still higher than under oxic conditions. Whilst benthic foraminiferal Mn / Ca has been conventionally used as an indicator of contamination by Mn oxyhydroxide or Mn carbonate (Boyle, 1983;Barker et al, 2003), new studies are pioneering Mn / Ca as a potential proxy of related changes in bottom/pore-water oxygen and redox conditions (Ní Fhlaithearta et al, 2010;Glock et al, 2012;Groeneveld and Filipsson, 2013;Koho et al, 2015). Mn / Ca signatures of the ambient bottom water are recorded by benthic foraminifera.…”

Encrustation and trace element composition of <i>Neogloboquadrina dutertrei</i> assessed from single chamber analyses – implications for paleotemperature estimates

“…These Mn/Ca may be used to infer changes in seawater Mn concentration due to variable terrigenous input (Klinkhammer et al, 2009). Culture studies with benthic foraminifera have shown that Mn uptake linearly relates to Mn concentration in the seawater (Munsel et al, 2010). Therefore, the observed (near) doubling in the median Mn/Ca in the inner layer thus may suggest a twofold increase in Mn concentration in the ambient seawater, likely related to enhanced terrigenous input via dust or lower sea level.…”

Bioerosion by microbial euendoliths in benthic foraminifera from heavy metal-polluted coastal environments of Portovesme (south-western Sardinia, Italy)

“…Benthic foraminifera secreting calcium carbonate shells are considered to be very sensitive to the environmental conditions of the host sea water (e.g. Boyle, 1981;Wefer et al, 1999;Lea, 2004;Munsel et al, 2010). Species distribution and population densities of foraminifera are in fact used for pollution monitoring (Alve, 1991(Alve, , 1995Yanko et al, 1994Yanko et al, , 1999Debenay et al, 2001Debenay et al, , 2005Coccioni et al, 2003Coccioni et al, , 2005; Armynot du Châtelet et al, 2004;Cherchi et al, 2009;Frontalini et al, 2009;Romano et al, 2009;Frontalini and Coccioni, 2011;Denoyelle et al, 2012;Foster et al, 2012).…”