Palladium in the coastal environment: speciation and determination.

Supervisor: Antonio Cobelo García (Instituto de Investigaciones Marinas, CSIC, Vigo)
Palladium (Pd) is considered as emerging contaminants due to its extensive use in automotiveindustry. Therefore, it is relevant to assess its speciation and concentration in natural waters inorder to understand its biogeochemical cycles and anthropogenic impact. In this study, Pdspeciation for the inorganic complexes in natural waters has been modelled to mimic the naturalwaters condition, although there are some uncertainties for the hydroxy and mixed hydroxyl chloro complexes stability constants. The organic speciation is proven to be more problematic,given the lack of stability constants data for Pd-organic complexes. But it is expected thatorganic complexation dominates the Pd speciation in natural waters.The lack of appropriate analytical methods for Pd determination results in the scarcity ofreported Pd concentrations in natural waters. Therefore, a method to analyse Pd in naturalwaters has been developed. The method used a commercially available resin Presep®Polychelate (Wako Fujifilm) for Pdpreconcentration and interference removal prior todetermination with ICP-MS. This method was then applied to measure the concentrations ofdissolved Pd along the salinity gradient in surface water of the Gironde Estuary, France. Theobserved Pd concentrations from the sampling campaign in November 2012 (moderate riverdischarge) and March 2013 (high river discharge) ranged from 0.027 to 0.055 ng/kg and from0.037 to 0.076 ng/kg, respectively. These concentrations are in the same order of magnitudewith the only available Pd concentration data in seawater reported by Lee (1983).