## 4 Conclusions  
The sediments in the waters of Cartagena Bay, mainly in the Playa Blanca region, showed levels of aluminum, iron, magnesium, and sodium (among others) pollution. These levels of pollutants in sediments, despite being known for decades in other studies at a global level, require additional investigations that can support the development of new public policies aimed at preserving the waters of Cartagena Bay in the future, emphasizing this study's contribution to the research community and the value added in results collected in the field and by satellite detection.  
Data collected by Sentinel-3B OLCI satellite imagery revealed high levels of chlorophyll, turbidity, and the potential for suspended pollution. The reflectance variable CHL443_NN presented its peak suspended pollution potential in the summer of 2021, with an improvement in this index in the winter of 2020. Climatic and meteorological differences between the seasons can explain this disparity. Furthermore, it was observed that in the central region of Cartagena Bay, an estuary receives much of the urban and rural pollution.  
The K-Means cluster analysis confirmed previous results, demonstrating the spatialization of the clusters and highlighting their relationship with the estuary. This confirms that pollutants and contaminants are dumped into Cartagena Bay through a point source and dispersed as they move away from the mainland, thus dispersing toxic nanoparticles throughout the ocean ecosystem. The need for new studies on the analysis of the dynamics of nanoparticle movement is evident, using the same methodology as this research to evaluate the influence of human actions on water resources on a global scale.  
Conceptualization, G.M., L.D.M. and G.P.S.; data curation, A.N.; formal analysis, L.S.M. and A.N.; funding acquisition, B.W.B.; investigation, R.T.L.; project administration, M.F.A.T. and A.N.; supervision, M.M.I. and G.M.; visualization, A.N.; writing--original draft preparation, M.M.I. and A.N.; writing--review and editing, M.L.S.O., C.G.R. and A.N. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
Figure 7: A map of clusters defined based on the demarcation of collection points using images from the Sentinel-3B OLCI satellite.  
**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.  
**Data Availability Statement:** Data are contained within the article.  
**Acknowledgments:** The authors thank the European Space Agency (ESA) and the U.S. National Aeronautics and Space Administration (NASA) for providing the unpublished and treated images from the Sentinel-3B SYN satellite and the NOAA Air Resources Laboratory (ARL) for giving the HYSPLIT transport and dispersion model and/or READY, used in this publication. We also thank the Center for Studies and Research on Urban Mobility (NEPMOUR+S/ATTUS), Brazil; Fundacao Meridiolan, Brazil. We thank FAPESC (Fundacao de Amparo a Pesquisa e Inovacao do Estado de Santa Catarina); Atlantic International Research Centre (AIR Centre) ([[https://www.airectre.org/Scholarship/](https://www.airectre.org/Scholarship/)]([https://www.airectre.org/Scholarship/](https://www.airectre.org/Scholarship/)), accessed on 26 May 2024), Portugal; and the National Council for Scientific and Technological Development (CNPq), Brazil. The authors thank Taif University, Saudi Arabia, for supporting this work through project number (TU-DSPP-2024-03).  
**Conflicts of Interest:** The authors declare no conflicts of interest.