Environmental impacts systematic analysis of ports disposed dredged sediments techniques

Abstract

The selection of sites for disposal of dredged sediments from port areas requires careful consideration. These sites used for disposal undergo several physical-chemical changes, which lead to further disturbances in the marine ecosystem, including biological processes, water quality and social activities. There is a growing concern on the impact of dredging on social and biological systems, however data about its impacts are scattered and not systematically organized. This review evaluated the socioenvironmental impacts caused by ocean disposal (ODP) and contained aquatic disposition (CAD) techniques using the Santos estuary channel (Baixada Santista, Brazil) as example. Data was collected through a systematic bibliographic and documentary review, searching for specific terms related to the Port of Santos and using the main academic databases available. Impacts identified in the review were analyzed qualitatively by their Magnitude and Importance attributes. Impacts were then assessed by degree of significance (i.e. very significant, significant and insignificant), based on the magnitude and importance classification. Data compiled through the systematic literature review were validated using a degree of significance matrix adapted from Leopold matrix. Findings suggested that the level of contamination of the sediments is the major criteria for the selection of the disposal methods. CAD technique showed more significant impacts due to the high load of contaminants associated with sediments that directly interfere in the quality of the physical-chemical parameters of the disposal site.ODP seemed to affect mostly fishing activity, while CAD has impaired the quality of life of residents around the estuary, interference in fishing activity and in protected areas. Overall, we conclude that the CAD technique presents more significant socioeconomic and environmental impacts for coastal environments. Our findings also highlight the importance of studies about environmental impact assessments for the elaboration of dredging plans in guiding decision making and future actions. .