Zinc incorporation in the miliolid foraminifer Pseudotriloculina rotunda under laboratory conditions

• Zinc incorporation into miliolid foraminiferal tests was experimentally tested
• Pseudotriloculina rotunda was cultured at several zinc concentrations for 70 days
• LA-ICP-MS analyses show that Zn is incorporated into calcite;
• Partition coefficients (DZn) decrease at increasing Zn/Caseawater ratios.

The incorporation rate of Zn into the calcareous tests of Pseudotriloculina rotunda was investigated in culture in order to evaluate the possibility of using Zn/Ca ratios as a pollution proxy. Foraminifera were incubated at zinc concentrations up to 10-fold higher than unpolluted seawater (sea + 10 mg Zn/L) during 70 days. New calcite was investigated under the Environmental Scanning Electron Microscope (ESEM), for potential alteration of test structure. Laser ablation-Inductively Coupled Plasma-Mass spectrometry (LA-ICP-MS) was used to quantify Zn contents. The analyses revealed that test structure is not visibly altered by the presence of zinc. However, significant Zn incorporation is detected by the LA-ICP-MS. The zinc partition coefficient, DZn, decreases at increasing Zn concentrations (from 4.03 ± 0.06 to 0.2 ± 0.01) and the zinc is incorporated into the calcite not necessarily linearly.