Particle bioturbation in Massachusetts Bay: Preliminary results using a new deliberate tracer technique

To better understand temporal and particle size-dependent bioturbation processes, we conducted a study of sediment mixing in Massachusetts Bay using a newly developed deliberate tracer technique. Sediments from a 32-m, fine-grained site were collected and the 38-62 («silt») and 63-125 («sand») μm fractions isolated. These particle-size fractions were labeled with two different noble metals (Au: silt & Ag: sand) using a thermal diffusion technique. Mixtures of the tracers were spread onto the seafloor in April and July 1992 by divers and were tube-cored (3 replicates) ∼ 80 d later in each case. Vertical profiles of the tracers were measured at μg/g (Ag) and ng/g (Au) levels by instrumental neutron activation analysis