Determination of the geographical origin of marine mussels (Mytilus spp.) using Nd/Nd ratios.

Geographical traceability of marine bivalves is critical to guarantee their quality and safeguard the interest of both consumers and producers. The neodymium isotopic ratio (Nd/Nd) of the coastal water mainly reflects the geology of its neighboring watershed, displaying the distinct and systematic variability at high level of geographical detail and thereby shedding light on its potential as a geochemical tracer. For the first time, the present study investigated the utility and robustness of Nd/Nd archived in mytilid mussel shells for geographical traceability purposes. The reproducibility of Nd/Nd ratios maintained in mussels shells from the same cohort demonstrates that the Nd isotopic ratio meets the major requirement for an ideal geochemical tracer, i.e., the biologically induced variation should be rather minimal. The distribution and variability of mussel shell Nd/Nd patterns were subsequently mapped along the Japanese and Chinese coastal waters. Neodymium isotopes of mussel shells record Nd/Nd variations among local regions and between the two countries, which are rather compatible with the ages and lithology of the continental bedrocks. These findings highlight the great potential of Nd/Nd for tracing the geographical origin of marine bivalves.