Microautoradiography (with combined liquid scintillation) applied to the study of trace metal uptake by suspended particles: initial results using ⁶³Ni as a tracer

We report the development of a microautoradiographic method for the study of trace metal-particle interactions in natural waters. This technique, in combination with conventional liquid scintillation counting methods, was applied to surface water samples from the Belgian coastal zone and Scheldt estuary. 63Ni was used as the metallic radio-tracer. Ni partitioning in our experimental system was shown to be a primarily abiotic process, driven by passive sorption reactions and limited in extent on a 24-h time scale by the slow reaction kinetics of Ni. Small particles (< 1 µm) were important as sorption sites, while large particles exhibited variable and particle-specific scavenging potential