<p>Mar Menor (SE, Spain) is one of the largest coastal lagoons in the Mediterranean basin. Its ecological and economic significance has led to its inclusion in several protection programmes, both on a national and international level. In the last decades, this semiconfined habitat has been under high anthropogenic pressure from agricultural, mining and tourism activities, which have resulted in significant changes, such as eutrophic events and their cascading ecological effects. Previous research suggests that this degradation is linked to the introduction of nutrients and contaminants to this ecosystem, which are accumulated in the sediments of the lagoon. In this work, sediment cores from key locations of the Mar Menor were collected in order to estimate the amount of accumulated chemical compounds, such as metals and organic compounds. The results of this study are used to reconstruct the historical record of contaminants, which can fuel future contamination episodes in the lagoon.  </p><p>  </p>

<p>The Mar Menor coastal lagoon (Spain) is a critical ecological and socioeconomic ecosystem and the first in Europe to be granted rights of personhood. However, pollution from past and present activities such as mining, agriculture, urbanization, and tourism threatens its health and ecological stability. Previous research has shown the importance of metal contamination in the lagoon and its link to nearby mining activities, but little consideration has been given to historical changes in this industry and in other potential metal sources. In this work, metal concentrations have been analyzed in 12 sediment cores dated with <sup>210</sup>Pb, allowing the reconstruction of the recent (last ~150 years) metal contamination in the lagoon. The main metal sources have been identified by using multivariate statistical methods. Metal contamination from mining activities (point-source pollution) peaked in the mid-20th century, whereas nonpoint-source metal contamination reached its highest level in more recent decades. Despite the current decrease in metal deposition trends, concentrations in surface sediments still exceed sediment quality and ecotoxicological thresholds in areas close to former mining sites. Therefore, they need to be considered in future management strategies, which should also include the evaluation of sources and processes that are still supplying them to the lagoon.</p> <p> </p>