Fuentes y distribución de microcontaminantes orgánicos regulados y emergentes en la laguna costera del Mar Menor

Abstract

ABSTRACT The Mar Menor lagoon is a system of high ecological value that concentrates many human activities such as urban development, tourism, intensive agriculture, mining, etc. Although there have been studies on the effects of eutrophication and the entry of trace metals associated with mining activities, information on the presence and distribution of organic contaminants was very scarce. Therefore, the development of this PhD thesis was proposed, its main objective is to characterize the main sources of input of legacy, and emerging contaminants to the Mar Menor lagoon and its subsequent distribution in different environmental compartments (water, sediment and biota). Specifically organochlorine pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), current use pesticides and drugs were considered. Specific methods of extraction were applied (stir bar sorption extraction, Soxhlet, ultrasound or pressurized liquid extraction) depending on the environmental matrix, purification and analysis for different groups of compounds (liquid or gas chromatography preferably with detection chromatography mass spectrometry). To do so, a quarterly sampling was performed for two years in El Albujón watercourse and the Mar Menor lagoon (surface and seawater), samplings for sediments were performed every six months and with a periodicity quarterly in air using passive samplers. In the last year (2010), also samples of biota were taken in spring and autumn. The annual input of organic pollutants from the mouth of El Albujón watercourse was estimated at 27.4 kg, of which 11.4 kg were drugs, while the rest were PAHs and pesticides. In spring, the majority was insecticides and antibiotics, in summer, herbicides and antihypertensives; in autumn and winter, herbicides and analgesics were predominant. The heavy daily variations of concentrations in the watercourse indicate that spot sampling strategy is not representative in this type of system, and can cause episodes of mortality in fish that live there, since some compounds can exceed the standards of environmental quality. It was also estimated at 40.9 kg the input of these pollutants during two floods (September 2009) through this watercourse showing its great importance in this type of system. In air, the presence of PAHs, PCBs and current use pesticides was confirmed, detecting the highest concentrations of PAHs near the airport, especially in winter, and near the crop fields for pesticides (herbicides in winter and insecticides in autumn). The spatial distribution of pollutants in seawater and sediment identified other input sources besides the own El Albujón watercourse, such as groundwater at the major watercourses and atmospheric deposition for pesticides, urban nuclei and ports for PAHs or uncontrolled discharges in the case of residual drugs. Terrigenous contributions of floods significantly increased the concentration of p, p'-DDE in surface sediment from the center and south of the lagoon, and reduced the PCBs concentration. The distribution of PAHs and pesticides in sediment was heterogeneous as a result of their different pathways, the hydrodynamics of the lagoon and the physicochemical properties of the sediment and each pollutant. It has also been found that the PAHs accumulate at similar levels to cockle, oyster and noble pen shell, while oyster and noble pen shell are able to accumulate more organochlorine contaminants. It has been characterized for the first time drug bioaccumulation in molluscs and fish in a Spanish coastal system, more drugs were detected in the muscle of golden grey mullet than in molluscs. Therefore, biomarkers proposed for the Mar Menor are: oyster for PAHs and organochlorine contaminants; and the muscle of golden grey mullet for drugs.