Hijos del mar de plásticos.

Hace aproximadamente 25 años que la población del Poniente Almeriense comenzó a experimentar un cambio radical. Ésta aumentó debido a la llegada de inmigrantes extranjeros en busca de trabajo.Con el reportaje ‘Hijos del mar de plásticos’ se pretende arrojar un poco de luz sobre el tema, mostrando testimonios de personas que o nacieron en Almería o llegaron siendo niños. Además de mostrar y fomentar la multiculturalidad en la zona, poniendo de manifiesto que la convivencia de culturas distintas es posible.

Cold vapour generation electrothermal atomic absorption spectrometry and solid phase extraction based on a new nanosorbent for sensitive HG determination in environmental samples (sea water and river water)

Mercury is not an essential element for plant or animal life and it is a potential environmental toxic because of its tendency to form covalent bonds with organic molecules and the high stability of the Hg-C bond. Reports estimate a total mercury concentration in natural waters ranging from 0.2 to 100 ng L-1. Due to this fact, highly sensitive methods are required for direct determination of such extremely low levels. In this work, a rapid and simple method was developed for separation and preconcentration of mercury by flow injection solid phase extraction coupled with on-line chemical vapour generation electrothermal atomic absorption spectrometry. The system is based on chelating retention of the analyte onto the mini column filled with a mesoporous silica functionalized with 1,5 bis (di-2-pyridyl) methylene thiocarbohydrazide. The main aim of this work was to develop a precise and accurate method for the determination of the Hg. Under the optima conditions and 120 s preconcentration time, the detection limit obtained was 0.009 μg L-1, with RSDs 3.7 % for 0.2 μg L-1, 4.8 % for 1 μg L-1 and enrichment factor 4, Furthermore, the method proposed has permitted the determination of Hg with a reduction in the analysis time, the sample throughput was about 18 h-1, low consumption of reagents and sample volume. The method was applied to the determination of Hg in sea water and river water. For the quality control of the analytical performance and the validation of the newly developed method, the analysis of two certified samples, TMDA 54.4 Fortified Lake, and LGC6187 River sediment was addressed. The results showed good agreement with the certified values.

Adquisición y evaluación de competencias mediante rúbricas. Estudio cualitativo de las percepciones del profesorado universitario en México

Las nuevas tendencias en la enseñanza universitaria apuestan por un modelo de evaluación estrechamente vinculado al concepto de evaluación formativa que promueve el enfoque competencial. En este contexto, las rúbricas de evaluación, son algunos de los instrumentos más útiles para obtener evidencias de la adquisición de competencias. En este sentido, el objetivo del estudio era conocer la percepción que concepciones tiene el profesorado mexicano sobre evaluación de competencias y aprendizaje complejo en la universidad, a partir del uso de rúbricas de evaluación. Se trataba de identificar en qué medida el profesorado está evaluando por competencias o si, por el contrario, continua más identificado con la evaluación de aspectos disciplinares. También, se perseguía conocer el sentido y el alcance de las rúbricas como recurso de innovación, teniendo en cuenta los aspectos técnicos y pedagógicos presentes en su diseño e implementación. La metodología empleada fue la entrevista en profundidad con el propósito de adquirir una comprensión detallada de las experiencias y perspectivas del profesorado en relación a la evaluación de competencias mediante rúbricas. Los resultados y conclusiones del estudio permiten identificar necesidades formativas del profesorado mexicano que desea evaluar por competencias. La discusión con otras investigaciones realizadas en Europa permitió además analizar divergencias y convergencias en la manera en que son concebidos estos instrumentos de evaluación.

Effect of organic amendments on the afforestation performance of plant species on degraded semiarid conditions

Vegetation plays a fundamental role in soil conservation, so it is common to consider an increase in vegetation cover as one of the techniques to mitigate the effects of desertification in Mediterranean forest environments. There are two factors limiting the establishment and growth of seedlings in dry environments: (i) an excessive radiation and, (ii) the limited availability of water during the summer drought. During an afforestation plan, soil preparation is always necessary to reduce sapling mortality. The goal of this study was to analyze the effect of various organic amendments on soil according to chemical and hydrological properties, and to assess the effects of these parameters on an afforestal proposal under Mediterranean climate conditions. Five amendments were applied in an experimental set of plots: straw mulching (SM); mulch with chipped branches of Aleppo Pine (PM); TerraCotten hydroabsobent polymers (HP); sewage sludge (RU); sheep manure (SH) and control (C). Plots were afforested following the same spatial pattern, and amendments were mixed with the soil at the rate 10 Mg ha -1 . Under bare soil conditions (C), most of mortalities occurred during the summer period of the first year. A substantial positive effect of SM, PM and HP on the survival rates have been clearly observed. Conversely, when the soil was amended with SH, the survival rate quickly decreased or remained more or less constant regarding to C. In this study, the lack of differences on chemical properties indicates that there may exist other reasons to justify the differences that were found in the pattern of vegetation. However, regarding to the hydrological properties some differences have been found. In C, soils were registered below the wilting point during 4 months a year, and therefore, in the area of water unusable by plants. These months were coinciding with the summer Mediterranean drought and can justify the high mortality found on plants. Conversely, in SM, PM and HP, soil moisture remained below the wilting point less period than C and, the plant available water was also higher. In these treatments, the survival sapling rates measured were the highest. SH showed water holding capacity slightly more limited than C. For this treatment, the survival sapling rates measured were the lowest. In conclusion, from a land management standpoint, the PM, SM and HP have been proved as a significant method to reduce sapling mortality rates during the Mediterranean summer drought.