Quality and Disposal of Dredged Sediments from Tidal Deltas in Subtropical Bays in Southern Brazil

Abstract

In order to measure the contamination of dredged and beach sediments and the applicability of sediment quality guidelines in a wet subtropical region of southern Brazil, the areas surrounding both the Paranaguá and Babitonga estuaries were studied, including their harbour zones and adjacent beaches. Investigation of the sampled sediments comprised optical and electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometry, and physicochemical and toxicological analyses. Additionally, data provided by the harbours administrations on dredged volumes, sedimentology, and coastal dynamics were compared. It was determined that the studied sediments, especially the ones from both tidal deltas, have similar characteristics, including physical and chemical parameters. It was also confirmed that tidal deltas are depositional areas with low potential to accumulate pollutants. Therefore, the current disposal of this scarce sandy material during dredging might not be beneficial, considering the significant sand removal amount from the coastal depositional system.

Keywords: Beach nourishment; Dredged channels; Estuarine sediments; Sediment quality guidelines; Tidal deltas.