Arsenic (As) is the one of the main environmental pollutant and phytoremediation is an effective tool for its removal of the environment. In this study, Pistia stratiotes were exposed to seven As concentrations (0, 3, 7, 10, 13, 16 and 20 μM) and then, the influence of this metalloid on growth, mineral nutrition and photosynthesis were analyzed. It was observed that this species have a high affinity for As and pollutant uptake occurs rapidly. The uptake of Cu, Mn, Fe and P increased until the concentration of 13 μM, decreasing in higher concentrations.The Mg content also decreased from this same concentration. No effects were observed in the uptake of K, Ca and Zn. Growth rate and photosynthetic pigments content were negatively affected by As. Despite this decrease, the growth was maintained up to the concentration of 13 μM of As. The maintenance of growth and the change in nutrients uptake are probably related with the increase in antioxidant capacity of the plant, indicating resistance to the pollutant. In this way, P. stratiotes is probably an efficient phytoremediator of As, even when in concentrations up to one hundred times greater than those permitted in water for human consumption.

El Arsénico (As) es uno de los principales contaminantes ambientales y la fitorremediación se presenta como una herramienta efectiva para retirar este elemento del medio ambiente. En el presente estudio se analizó la influencia de este elemento en el crecimiento, nutrición mineral y fotosíntesis de Pistia stratiotes bajo siete concentraciones de As (0, 3, 7, 10, 13, 16 y 20 μM). Encontrándose gran afinidad de esta especie por el As, siendo que la absorción de este elemento ocurre deforma rápida afectando la absorción de nutrientes esenciales. En este sentido, la absorción de Cu, Mn, Fe y P aumentó hasta una concentración de 13 μM de As, disminuyendo en el caso de las mayores concentraciones, entre tanto se observó una disminución en la absorción de Mg. No fueron observados efectos sobre la absorción de K, Ca y Zn. A pesar que tanto la fotosíntesis como el crecimiento fueron negativamente afectados por las diferentes concentraciones de As la planta consiguió mantener una tasa reducida de crecimiento hasta la concentración de 13 μM. Esta situación así como las alteraciones observadas en la absorción de nutrientes, probablemente esté relacionada con el aumento en la capacidad antioxidativa de la planta, indicando una posible respuesta de resistencia de la planta frente a este elemento contaminante. De esta forma es probable concluir que P. stratiotes actúa como una eficiente fitorre-mediadora de As, aun en concentraciones cien veces mayor que los niveles permitidos en el agua apta para consumo humano.

The reactive oxygen species generation, lipid peroxidation and antioxidative enzyme response of water hyacinth and salvinia to Cd were evaluated. Cadmium was absorbed/accumulated mainly in the roots, but significant amounts also translocated to the leaves. No Cd effect on dry weight was detected, although toxicity symptoms were visible. Superoxide and H2O2 concentrations increased, in addition to lipid peroxidation in both species, especially in the leaves of salvinia. In general, antioxidative enzyme activities were reduced in both species following Cd treatment, especially in salvinia. Glutathione peroxidase (GPX, EC 1.11.1.9) activity decreased in water hyacinth but increased in salvinia. Glutathione S-transferase (GST, EC 2.5.1.18) activity increased in the leaves but decreased in the roots of both species. So, Cd induced ROS generation/accumulation, but the antioxidative enzymes were not able to combat the Cd-induced oxidative injury in these two species. Nevertheless, water hyacinth consistently showed a higher tolerance to Cd than salvinia.