Study warns of the impacts of human pollution on the Algarve continental shelf

Heavy metals and organic contaminants were detected along the coast of the Algarve, between Sagres and Portimão, according to a study published in the magazine Marine Pollution Bulletin.

The work reports the presence of various inorganic and organic pollutants related to human activity, including different heavy metals and even microplastics, proving that «human presence has left a polluting signature in the coastal area of the Algarve, with a negative impact, for example, in terms of biodiversity. The data obtained seem to indicate that in the 1960s there was a peak of pollution, but, curiously, in recent years, this pollution seems to be slowing down slightly, with the exception of the Arade river area, due to regular discharges that are made», reports Pedro Costa, from the Department of Earth Sciences, Faculty of Science and Technology, University of Coimbra (FCTUC), co-author of the scientific article.

Considering climate change, it is expected that «we will have more high-energy events, both in precipitation and in storms, which will cause more intense erosive phenomena. In Portugal, there are already a number of areas under pressure, which means that this problem will inevitably worsen. We have always had pollution, but with the changing climate forcing and the energy levels of these extreme events (tsunamis, storms and floods), phenomena that would be of little intensity could have serious negative consequences and serious imbalances in coastal systems», stresses the FCTUC researcher.

This study was developed as part of a pioneering international project that brings together more than two dozen researchers, called OnOff, which is led by Pedro Costa. This project chronographed extreme events (tsunamis and storms) and the effects of human contamination in this area of ​​Portugal over the last 12,000 years.

In addition to the University of Coimbra (UC), the OnOff project includes the University of Lisbon (UL), the University of Algarve (UAlg), the Hydrographic Institute and the Portuguese Environment Agency, in Portugal; the University of Aachen (Germany) and the United States Geological Survey.

Starting in 2018, OnOff essentially aims to fully reconstruct extreme events, such as tsunamis and storms, and their impacts on the Portuguese coast, based on geological evidence, that is, it «seeks to seek information from the seabed to carry out the reconstruction of events extremes, whether from tsunamis, storms or floods, and also from more recent phenomena, such as pollution», explains the leader of the study.

For this historical reconstruction of extreme events at sea to be possible, the scientists carried out a series of sea campaigns (underwater soundings) along the coast of the Algarve, collecting samples of water, sediments, and geophysical data between 500 meters and 30 meters in depth. depth. «This is the innovative aspect of the project because it shows a different archive that was not normally paid attention to and which allows a detailed reconstruction of the evolution of this region. The information obtained at sea is combined with data obtained on land, in the lagoon and estuarine areas of the Algarve», says Pedro Costa.

Certainly, this project contributes to «the understanding of the morphodynamic and hydrodynamic processes associated with tsunami waves and storms that hit the Portuguese coast and, by analogy, in other similar scenarios worldwide», he emphasizes. In addition, he concludes, he contributes to the «production of probable flooding scenarios by tsunamis and storms for the coast of Portugal (which is the most active tsunamigenic region in the Atlantic), thus supporting the management of coastal areas by government authorities with useful data in the planning, ordering and also operationalization».

The OnOff project is co-financed by the Fundação para a Ciência e a Tecnologia (FCT), by European funds and also by the Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), Brazil. The scientific article published in the Marine Pollution Bulletin, entitled “Contemporary pollution of surface sediments from the Algarve shelf, Portugal”.

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