Geochemistry of large benthic foraminifera Amphisorus hemprichii as a high-resolution proxy for lead pollution in coastal environments

Abstract

Anthropogenic lead (Pb) contamination resulting from the rapid growth of industrialization in coastal environments poses significant challenges. In this study, we report a novel approach utilising the large benthic foraminifera Amphisorus hemprichii as a biogeochemical archive for monitoring Pb pollution in tropical to warm-temperate coastal waters. Live juvenile specimens of A. hemprichii were cultured in the laboratory for 16 weeks with a range of seawater Pb concentrations. Lead uptake in both newly grown and pre-existing chambers of individual specimens was characterised using the microanalytical technique, Laser ablation-ICP mass spectrometry. We found that Pb concentration in the tests of cultured foraminifera in the laboratory is proportional to seawater [Pb] with the lead partition coefficient (KDPb) of 8.37 ± 0.3. This calibration together with a new biomineralisation model now enables A. hemprichii to be utilised as a naturally occurring bio-archive to quantitatively monitor anthropogenic Pb pollution in coastal waters.