ABSTRACT
Rare earth elements (REEs) are considered critical elements for technology and their extraction through mining activities is expected to increase in the future. Due to their chemical similarities, they often co-occur in minerals and thus their ecotoxicity should be assessed as a group/family. However, the available ecotoxicological studies focused mainly on the evaluation of the potential toxicological impacts of individual REEs rather than their mixtures. The aim of this study was therefore to evaluate the toxicity of a representative mixture of five REEs (La, Ce, Pr, Nd and Sm) spanning environmentally relevant concentrations ranging from 0.05X (29 µg REEs L-1) to 5X (2926 µg REEs L-1) to the test organism, Hydra vulgaris, at the morphological, reproductive and regenerative levels. The data showed that lethality occurred at concentrations near (2.5 fold) to those inducing sublethal effects after chronic exposure of 7 days. The mixture affected reproduction and head regeneration and even lethality at concentrations even below those reported at environmental concentration (0.5X = 293 µg REEs L-1) in lakes. This suggests that REEs concentrations found in lakes near mining activities could disrupt regeneration and impair embryonic development. Our data also revealed that combining the 5 REEs results in an antagonistic effect, suggesting that those elements share the same receptor and that low molecular weight and high radius elements (approaching iron) were less toxic. Taken together, hydra could be used as a sensitive model organism for the assessment of aquatic ecotoxicological risks of REE mixtures but further analyses of biochemical and gene expressions should improve our understanding of the long-term effects of REEs mixtures.
Subject(s)
Hydra , Metals, Rare Earth , Animals , Ecosystem , Ecotoxicology , Metals, Rare Earth/analysis , MiningABSTRACT
En este estudio analizamos la relación del estilo de apego adulto con las propiedades estructurales de las redes personales y el capital social de 67 directivos de la provincia de Quebec (Canadá). A través del análisis de conglomeramos detectamos dos perfiles relacionales diferenciados. El apego seguro se asocia con redes densas de lazos fuertes, comparativamente pequeñas. El estilo de evitación se relaciona en cambio con redes más amplias y centralizadas, con más lazos débiles. No se observaron diferencias significativas en la satisfacción con la carrera profesional en función del estilo de apego. Sin embargo, la satisfacción con la carrera mostró una relación significativa con la centralización de la red personal
In this study, we analyze the relationship of adult attachment style with the structural properties of personal networks and the social capital of 67 managers in the province of Quebec (Canada). Through cluster analysis, two differentiated relational profiles were detected. Secure attachment is associated with dense and comparatively small networks of strong ties. The avoidance dimension is related instead to larger and more centralized networks, with weaker ties. There were no significant differences in satisfaction with the professional career depending on the attachment style. However, satisfaction with the career showed a significant relationship with the centralization of the personal network
