Impacto de los residuos de la minería metálica sobre el ecosistema marino del Mar Menor

Abstract

[SPA] Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. El distrito minero de Cartagena-La Unión se encuentra situado junto al Mar Menor (SE, España), una de las mayores lagunas costeras mediterráneas. Aunque la actividad minera se detuvo hace varias décadas, los residuos mineros siguen entrando en la laguna, especialmente durante episodios de lluvias torrenciales, a través de ríos estacionales, localmente llamados "ramblas". Uno de los objetivos de esta tesis fue examinar la influencia de la actividad minera metálica en la composición de los sedimentos del Mar Menor, realizando un estudio evolutivo de dichos sedimentos mediante una caracterización integral de la granulometría, mineralogía, geoquímica y la materia orgánica de los fondos de esta laguna costera, a lo largo del espacio y del tiempo. Por otro lado, el uso de organismos marinos como biomonitores es una herramienta importante para la comprensión de cómo los cambios en la calidad del agua pueden afectar a la diversidad y la abundancia de la biota local. Debido a su capacidad para consumir plancton y filtrar grandes volúmenes de agua, las medusas son capaces de acumular metales a partir del agua del mar. La combinación de su capacidad para acumular elementos traza, su comportamiento sedentario, su fácil identificación, la presencia en comunidades de interés y su tolerancia a cambios físico-químicos en el medio realzan el interés de estos organismos para ser considerados como biomonitores en el medio ambiente costero. Para determinar la biodisponibilidad de elementos traza en la laguna del Mar Menor, se ha evaluado la capacidad de dos especies alóctonas de medusas, Cotylorhiza tuberculata y Rhizostoma pulmo, muestreadas en diferentes partes de la laguna, para bioacumular metales y metaloides en sus tejidos (campana y brazos orales). Se midieron los principales contaminantes y se compararon las concentraciones de estos elementos traza entre el agua de mar y las medusas para determinar si estas eran capaces de acumularlos. También se investigaron las posibles correlaciones entre el tamaño de las medusas y su concentración de elementos traza, la concentración entre el agua de mar y las medusas y, finalmente, correlaciones entre elementos traza acumulados por las medusas. [ENG] The mining district of Cartagena-La Unión is located next to the Mar Menor (SE, Spain), one of the largest coastal lagoons in the Mediterranean Sea. Although mining activities stopped several decades ago, mining residuals continue to enter the lagoon, especially when torrential rains occur, through seasonal rivers, locally called “ramblas”. One of the objectives of this thesis was to examine the influence of metal mining activities on the composition of sediments of the Mar Menor lagoon, studying the evolution of these sediments through a comprehensive characterization of particle size, mineralogy, geochemistry and organic matter of the bottoms of this coastal lagoon, over time and space. On the other hand, the use of marine organisms as biomonitors is an important tool for understanding how changes in water quality can affect the diversity and abundance of local biota. Because of its ability to consume plankton and filter large volumes of water, jellyfish may be able to accumulate metals in seawater. The combination of the ability for accumulating metals, sedentary behaviour, easy identification, presence in the communities of interest and tolerance to physical and chemical changes in their environment enhance the interest of these organisms as biomonitors in coastal marine environments. To determine the bioavailability of trace elements in the lagoon of the Mar Menor, it was evaluated the ability of two non-native species of jellyfish, Cotylorhiza tuberculata and Rhizostoma pulmo, collected from different parts of the coastal lagoon, to bioaccumulate metals and metalloids in their tissues (bell and oral arm). Main pollutants were measured and compared to ambient seawater concentrations from the collection sites to determine if these species were capable of accumulating trace elements. Possible correlations between jellyfish size and element concentration has also been investigated, between seawater and jellyfish metal concentration and, finally, inter-element correlations in metals accumulated by jellyfish.

[ENG] This doctoral dissertation has been presented in the form of thesis by publication. The mining district of Cartagena-La Unión is located next to the Mar Menor (SE, Spain), one of the largest coastal lagoons in the Mediterranean Sea. Although mining activities stopped several decades ago, mining residuals continue to enter the lagoon, especially when torrential rains occur, through seasonal rivers, locally called “ramblas”. One of the objectives of this thesis was to examine the influence of metal mining activities on the composition of sediments of the Mar Menor lagoon, studying the evolution of these sediments through a comprehensive characterization of particle size, mineralogy, geochemistry and organic matter of the bottoms of this coastal lagoon, over time and space. On the other hand, the use of marine organisms as biomonitors is an important tool for understanding how changes in water quality can affect the diversity and abundance of local biota. Because of its ability to consume plankton and filter large volumes of water, jellyfish may be able to accumulate metals in seawater. The combination of the ability for accumulating metals, sedentary behaviour, easy identification, presence in the communities of interest and tolerance to physical and chemical changes in their environment enhance the interest of these organisms as biomonitors in coastal marine environments. To determine the bioavailability of trace elements in the lagoon of the Mar Menor, it was evaluated the ability of two non-native species of jellyfish, Cotylorhiza tuberculata and Rhizostoma pulmo, collected from different parts of the coastal lagoon, to bioaccumulate metals and metalloids in their tissues (bell and oral arm). Main pollutants were measured and compared to ambient seawater concentrations from the collection sites to determine if these species were capable of accumulating trace elements. Possible correlations between jellyfish size and element concentration has also been investigated, between seawater and jellyfish metal concentration and, finally, inter-element correlations in metals accumulated by jellyfish.