[en] Highlights: • Plastics and cigarette butts (CB) were dominant litter in Santos beaches in all seasons. • Plastic and CB amounts were high in summer compared to autumn. • The presence of beach users and local hydrodynamic influenced marine litter densities. • Santos beaches were classified as dirty or extremely dirty throughout the year. • Marine litter in Santos is a serious economic, health and environmental issue. Seasonal distribution of Marine Litter (ML) on Santos beaches was assessed using a citizen science strategy. Plastics and cigarette butts (CB) were the dominant items in all sampling campaigns. Seasonal distribution did not result in significant differences for most items. Plastic and CB amounts were high in summer compared to autumn. For all sampled sites the presence of beach users influenced ML densities. However, results showed that some sites presented an additional influence of local hydrodynamic. Moderate amounts of hazardous items including metal, glass, CB, sanitary waste and plastic tubes used to pack and market illicit drugs represented between 20.8 and 31% of all ML over the seasons. The beaches of Santos were classified as dirty in autumn and spring and as extremely dirty in winter and summer. These findings can serve as a baseline to support mitigating actions by public authorities and start monitoring programs of ML not only in Santos but also in other urbanized beaches.

[en] Sediment dredging impacts coastal environments by promoting the resuspension of fine particles and remobilization of contaminants that may trigger toxic effects. In this study, we evaluated the sediment quality in harbor areas of Mucuripe bay, a semi-arid ecosystem located in Ceará state (Brazil), which is subject to dredging activities. A sampling survey was conducted right after dredging operations and data compared to another survey performed prior dredging. Sediments were analyzed for fine particles, organic carbon, nutrients, metals, hydrocarbons, and tributyltin (TBT). Toxicity of whole-sediment and liquid phase exposures were also determined. The concentrations of Cd, Cr, Cu, and Zn decreased after dredging, which was confirmed by the geoaccumulation index. Levels of TBT dropped while phosphorus, aliphatic and polycyclic aromatic hydrocarbons increased. Toxic effects persisted, indicating a post-dredging recontamination combined with other sources such as urban runoff, wastewater discharges, harbor activities, and antifouling particles. Data from Mucuripe and Pecém harbors were compiled and site-specific sediment quality values (SQVs) were developed by using multivariate methods. The threshold values proposed by our study were lower and more effective to predict toxicity compared to international guidelines, indicating levels of contamination for this tropical region in which toxic effects may occur. Considering the large geographic area with different sediment characteristics of the Brazilian coast, this study represents a significant contribution to sediment toxicity assessment of dredging activities in semi-arid environments.

[en] Highlights: • Marine Protected Areas analyzed for sediment contamination and toxicity • Contamination levels in sediments were minimal. • No toxicity observed • Baseline levels for the monitoring of Marine Protected Areas are provided. Recent studies have shown that the effectiveness of establishing Marine Protected Areas (MPAs) is threatened by toxic effects of contaminants. São Paulo is the most economically developed state of Brazil, and its coast is protected by a system of MPAs, including the North Shore Marine Protected Area (NSMPA). The present study provides a first assessment of sediment quality in NSMPA and two reference sites. Concentrations of arsenic (As), metals (Al, Fe, Cd, Cr, Cu, Ni, Pb, and Zn) and polycyclic aromatic hydrocarbons (PAHs) and its sources were determined. Comparisons with sediment quality guidelines indicated low contamination, as confirmed by the Geoaccumulation Index, which classified the results as background levels. Whole-sediment exposures of the amphipod Tiburonella viscana were performed to estimate possible acute effects, but samples exhibited no toxicity. The results presented in this study represent a baseline for further monitoring programs of MPAs, supporting conservation actions of management plans.