SIMBIOSIS BIOLOGÍA-EDUCACIÓN BAJO EL PRISMA DE LA CONTEXTUALIZACIÓN DE CONTENIDOS: EL CASO DEL MAR MENOR

El proceso de enseñanza-aprendizaje en Educación Secundaria Obligatoria (ESO) no tiene en cuenta la contextualización de contenidos en Biología y Geología, haciendo que los estudiantes no encuentren motivación por su estudio y presenten dificultades en el proceso de aprendizaje, provocando que éstos, a su vez, no adquieran actitudes en favor de la conservación y protección del medio natural. El presente estudio se enmarca en una clase de 1º de ESO (n=30) de un instituto localizado en el municipio de Murcia, con un nivel socioeconómico medio-alto. Se emplea una propuesta educativa, con una secuencia de actividades (6 sesiones de 15 actividades), en la que se pretende la contextualización de los contenidos relacionados con la dinámica de los ecosistemas. Para ello, se utiliza un ecosistema presente en la Región de Murcia para abordar los contenidos, concretamente, el Mar Menor, sirviendo de hilo conductor de dichas actividades. Con ello, los contenidos se encuentran contextualizados y se intenta promover la concienciación y sensibilización por la conservación y protección del medio ambiente. Para su implementación, se establece una selección de objetivos, relación con las competencias clave, análisis del libro de texto utilizado, diseño de las actividades y establecimiento del método de evaluación. Tras la implementación de la propuesta educativa, la mayoría de estudiantes muestra motivación por el estudio del temario, así como una mayor comprensión del mismo, indicando que la contextualización de los contenidos y uso variado de metodología, estrategias y recursos didácticos es positiva en el proceso de enseñanza-aprendizaje y promoción de actitudes proambientales.

Screening and Quantification of Micro(Nano)Plastics and Plastic Additives in the Seawater of Mar Menor Lagoon

In this work a suspect-screening approach was employed to assess the polymers and plastic additives of micro(nano)plastics (NPL/MPLs) of size ranges from the nm range to 20 μm present in seawater from the top 5 cm of the Mar Menor lagoon during two sampling campaigns (summer and winter), as well of other potentially adsorbed compounds onto the plastic particles surfaces and suspended material. The identification of NPL/MPLs has been based on characteristic Kendrick Mass Defect analysis for each polymer type in mass spectra. The applied methodology allowed to identify NPLs/MPLs of polystyrene (PS), polyethylene (PE), polyisoprene (PI), polybutadiene (PBD), polypropylene (PP), polyamides (PA), polyvinylchloride (PVC), n-isopropylacrylamide (PNIPAm), and polydimethylsiloxanes. In addition, PS, PE, PI, PBD, PP, PA, and PVC were confirmed with standards, and the equivalent concentrations were quantified. The results of this study showed that most frequently found compounds were PP, PE, PA and PNIPAm, while the compound found at higher concentrations was by far PP reaching the 9,303 ± 366 ng/mL in one of the samples. A total number of 135 chemical compounds were tentatively identified, 74 of them plastic additives and compounds used in the polymers manufacture or coming from the polymer’s decomposition. In relation to plastic additives, the more frequently tentatively identified compounds were plasticizers such as phthalates group; stabilizers such as antioxidants (e.g., distearyl 3,3′-thiodipropionate, 2,5-di-tert-butylhydroquinone), and UV filters as benzotriazoles. Several flame retardants of the group of phosphates were as well detected. The other compounds tentatively identified in the samples were pharmaceuticals, pesticides, food additives, flavors and natural products that were attached onto the plastic particles and particulate matter from surrounding waters. In regards to the seasonal variation, during the summer a major number of compounds were tentatively detected, while de concentrations of polymers were slightly higher in winter. The spatial distribution showed higher contamination in the southern part of the coastal lagoon.

Commercial Gilthead Seabream (Sparus aurata L.) from the Mar Menor Coastal Lagoon as Hotspots of Microplastic Accumulation in the Digestive System

This paper presents the results on the presence and characterization of microplastics (MP) in the gastrointestinal tract of gilthead seabream (Sparus aurata L.), a species of commercial interest from the Mar Menor coastal lagoon in Southeast Spain. This is the first time that microplastic ingestion is recorded in any species from this semi-enclosed bay. Stomach and intestine from a total of 17 specimens captured by local fishermen were processed, and microplastic particles and fibers found in all of them were displayed. Overall, 40.32% (279/692) of total isolated microparticles proved to be microplastics; i.e., <5 mm, as identified by FTIR spectroscopy. The average value by fish was 20.11 ± 2.94 MP kg−1, corresponding to average concentrations of 3912.06 ± 791.24 and 1562.17 ± 402.04 MP by kg stomach and intestine, respectively. Four MP forms were isolated: fiber (71.68%), fragment (21.15%), film (6.81%), and microbead (0.36%), with sizes ranging from 91 µm to 5 mm, an average of 0.83 ± 0.04 mm, and no statistically significant differences between mean sizes in stomach and intestine samples (F-test = 0.004; p = 0.936). Nine polymer types were detected, although most of fibers remained unidentified because of their small size, the presence of polymer additives, or closely adhered pollutants despite the oxidizing digestion carried out to eliminate organic matter. No significant correlation was found between main biological parameters and ingested microplastics, and high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene polypropylene (PEP), and polyvinyl (PV) were identified as the most abundant polymers. The average microplastic ingestion in this study area was higher than those reported in most studies within the Mediterranean Sea, and closely related to microplastic pollution in the surrounding area, although with a predominance of fiber form mainly due to fishery activities.