Dredged material characterization and management frameworks: A case study at the port Vilagarcia (NW, Spain).

The potential impact of dredged sediment has been assessed at sixteen areas of the high-traffic port of Vilagarcia (Northwest Spanish Atlantic coast). The assessment has been done by three weight-of-evidence tools, which integrated data on sediment characteristics and toxicity responses of Ampelisca brevicornis, Vibrio fischeri and eggs and embryos of Paracentrotus lividus. Two of the tools also represented management options regarding the disposal of dredged material. The comparison of the logic in these tools revealed essential differences in the type and the necessity of bioassays and threshold values for chemical concentrations. However, despite this difference, assessment results and the derived management options coincided in most of the sediments. The potential toxicity of sediments was relatively low especially for eggs and embryos possibly due to different contaminant availability in solid and liquid phases. The importance of a battery of toxicity tests in the dredged material quality assessment has been emphasized to avoid an underestimation of sediment toxicity for solid phase organisms, if only liquid phase responses are considered. The potential false implications, which may result from the application of the third tool, were highlighted. The strengths and weaknesses of the tools were discussed from the dredged material management perspective.