*3.3. Analytical Procedures*

Trace metals analysis was performed by means of Flame and Graphite Furnace AAS (Varian SpectrAA-200 and Varian SpectrAA-640 Zeeman) (Varian, Australia), depending on the concentration levels of each determined element. Procedural blanks were run in the same way as samples and were usually below Limits of Detections (LOD), reported in Table 1.


*J. Mar. Sci. Eng.* **2019**, *7*, 307

The accuracy and repeatability of dissolved metals determinations by the Chelex-100 resin has been tested in the laboratory using spiked seawater samples at three concentration levels, as well as by analyzing the certified reference material (CRM) CASS-4 (from National Research Council of Canada, NRCC) (Table 1). In the case of the sediment samples, the accuracy and repeatability of total sediment digestions was evaluated by analyzing the certified reference materials PACS-2 (NRCC) with satisfactory results (Table 1).
