Catálogo de la familia <em>Orchidaceae</em> en Guinea Ecuatorial

Se presenta un catálogo actualizado de las especies y táxones infraespecíficos de la familia Orchidaceae en Guinea Ecuatorial, obtenido a partir de testimonios de herbario y revisión bibliográfica. Nuestros resultados indican la presencia de 225 táxones más 12 que requieren confirmación en el conjunto del territorio (Annobón, Bioko y Río Muni), incluidos en 43 géneros y 10 tribus pertenecientes a las subfamilias Vanilloideae, Orchidoideae y Epidendroideae. Se aportan 88 táxones más en el catálogo de Río Muni respecto a publicaciones precedentes. La tribu Vandeae es la más representada, con 118 táxones. Atendiendo al hábito, 53 táxones son terrestres, seis son trepadores y 166 son epífitos. La mayor riqueza de orquídeas se manifiesta en la isla de Bioko y en las provincias occidentales de Río Muni. De las 31 especies descritas sobre materiales ecuatoguineanos, seis son consideradas endemismos de Guinea Ecuatorial.

Mercury content in vegetation and soils of the Almadén mining area (Spain)

The Almadén area is an exceptional case of mercury concentration in the world, where cinnabar is the predominant mineralised form. Mining activities have been carried out over the past two thousand years and once this activity is concluded, a restoration of the environment is necessary for the affected areas. That implies the selection, optimisation and application of the most appropriate techniques focused on the recovery of contaminated areas. Phytotechnology is one of the proposed techniques, which considers the use of plants due to the low environmental impact and their proved efficiency. In this framework, it is necessary to study the behaviour of mercury in the soil-plant system and to determine the mercury absorption capacity of the different Almadén plant species. Therefore, field and laboratory studies have been carried out to determine the easily available forms of mercury in ten test plots in the Almadén area and the resulting data is related to the mercury accumulation in different plant species of the studied territory. Special attention is given to the easily available forms of mercury in the analysed soils and used as the transfer factor for the Hg-availability index that relates the amount of mercury in a plant with the total amount of mercury in a soil and with the easily available forms. The result of this experimental work is selecting the plant species suitable to be used in a future implementation of phytotechnologies in this area.

Mercury bioaccumulation and phytotoxicity in two wild plant species of Almadén area

Mercury is a widely distributed environmental pollutant, able to induce toxicity in living organisms, including higher plants. Some plant species are able to grow in mine sites, like the Almadén zone in Spain. Our study focus on two of these plant species, Rumex induratus and Marrubium vulgare and their responses to natural Hg exposure. Total Hg concentration in the soil below the plants could be classified as toxic, although the available fraction was low. Hg availability was higher for the M. vulgare than for the R. induratus plot. Hg concentrations in field plants of R. induratus and M. vulgare grown on these soils can be considered as phytotoxic, although no symptoms of Hg toxicity were observed in any of them. According to the BAF ([Hg](tissue)/[Hg](avail)), R. induratus showed a higher ability in Hg uptake and translocation to shoots, as well as higher concentrations of MDA and -SH:Hg ratios, so that this plant is more sensitive to Hg than M. vulgare. The resistance to Hg and the capability to extract Hg from the soil make both M. vulgare and R. induratus good candidates for Hg phytoremediation of contaminated soils.