The Coastal Ocean Observation System of Murcia Region (OOCMUR) was established in 2008 as a major scientific and technological infrastructure in Spain with the main objective of studying the impact of global climate change in the Mediterranean. The coastal lagoon of Mar Menor in southeast Spain was chosen as the first region to be monitored because it is one of the most hypersaline coastal lagoons in the Mediterranean, with a limited exchange of water with the open sea, and it is the largest in Europe. Wireless sensor networks (WSNs) offer an efficient and innovative solution for oceanographic monitoring, allowing a higher density sensor deployment, at a lower cost. This paper presents the design of an ad hoc WSN system and a control software for Mar Menor monitoring using a buoy structure with sensors, energy harvesting, and communications platform. The study focuses on the oceanographic interest of the selected marine area, details of network deployment, the custom-designed sensor nodes, and the results of system operation.

Coastal enclosed ecosystems, such as lagoons, are vulnerable to anthropogenic impacts because they favor the accumulation of contaminants from the surrounding watersheds, particularly in their sediments. Europe's largest saltwater lagoon, the Mar Menor (SE, Iberian Peninsula), is a highly impacted ecosystem and the first in the continent to be granted personhood rights. Based on a high-resolution spatial and temporal dataset, we present the historical reconstruction of metal contamination in this ecosystem during the last century. Our results highlight that sediment metal contamination has been mainly driven by the development of the mining industry in the nearby Sierra Minera de Cartagena-La Unión in the late 19th and until the mid-20th century when premeditated mining spills were forbidden. Runoff from former mining areas still transported metals to the lagoon even after mining ceased in the 1990s. The southern sector of the lagoon, closest to mining-affected ephemeral streams, is the most impacted by metal contamination and holds the highest metal stocks. Stocks since 1900 for the entire lagoon reached values of 9200, 1.6, 450, 270, 10,000, and 12 tons of Pb, Hg, As, Cu, Zn, and Ag, respectively. Maxima concentrations were reached in the mid-20th century, with values of 3400, 0.53, 100, 50, 3700, and 5.5 mg·kg^-1 for Pb, Hg, As, Cu, Zn, and Ag. Afterward, while some metals' concentrations declined, others were still supplied to the sediments through runoff from former mining areas and sources related to urban expansion. Metal concentrations reported in this study surpass sediment quality guidelines and are generally higher than those found in similar ecosystems globally. Current surface metal concentrations are lower than during most of the 20th century, and sediments seem to retain metal stocks effectively. However, climate change and eutrophication could increase the risk of metal remobilization, further impacting this already vulnerable ecosystem. This study emphasizes the need for attention to managing coastal enclosed ecosystems, where global change impacts can exacerbate the impact of legacy contamination.

The use of dispersive liquid–liquid microextraction (DLLME) is proposed for the preconcentration of thirteen lipophilic marine toxins in seawater samples. For this purpose, 0.5 mL of methanol and 440 µL of chloroform were injected into 12 mL of sample. The enriched organic phase, once evaporated and reconstituted in methanol, was analyzed by reversed-phase liquid chromatography with triple-quadrupole tandem mass spectrometry. A central composite design multivariate method was used to optimize the interrelated parameters affecting DLLME efficiency. The absence of any matrix effect in the samples allowed them to be quantified against aqueous standards. The optimized procedure was validated by recovery studies, which provided values in the 82–123% range. The detection limits varied between 0.2 and 5.7 ng L⁻¹, depending on the analyte, and the intraday precision values were in the 0.1–7.5% range in terms of relative standard deviation. Ten water samples taken from different points of the Mar Menor lagoon were analyzed and were found to be free of the studied toxins.