RESUMO
A natural wetland in Mexico City Metropolitan Area is one of the main suppliers of crops and flowers, and in consequence its canals hold a high concentration of organochlorine (OC) and organophosphorus (OP) pesticides. There is also an extensive population of water hyacinth (Eichhornia crassipes), which is considered a plague; but literature suggests water hyacinth may be used as a phytoremediator. This study demonstrates bioaccumulation difference for the OC in vivo suggesting their bioaccumulation is ruled by their log K(ow), while all the OP showed bioaccumulation regardless of their log K(ow). The higher bioaccumulation factors (BAF) of the accumulated OC pesticides cannot be explained by their log K(ow), suggesting that the OC pesticides may also be transported passively into the plant. Translocation ratios showed that water hyacinth is an accumulating plant with phytoremediation potential for all organophosphorus pesticides studied and some organochlorine pesticides. An equation for free water surface wetlands with floating macrophytes, commonly used for the construction of water-cleaning wetlands, showed removal of the pesticides by the wetland with room for improvement with appropriate management.
Assuntos
Eichhornia/metabolismo , Hidrocarbonetos Clorados/metabolismo , Compostos Organofosforados/metabolismo , Praguicidas/metabolismo , Poluentes Químicos da Água/metabolismo , Purificação da Água , Irrigação Agrícola , Biodegradação Ambiental , Cidades , MéxicoRESUMO
Environmental metal pollution is one of the major problems faced by humankind. This type of pollution affects aquatic systems (estuaries, coastal lagoons, etc.), which are very dynamic systems, therefore making the study of the effects on the organisms that inhabit them an essential issue. In this study, the capacity of metal regulation by decapod crustacean Penaeus vannamei juveniles was determined. The effects of zinc, lead, and cadmium were tested individually and as a metal mixture exposure to determine possible synergism. The results showed that juvenile shrimps were capable of regulating zinc and lead, whereas cadmium was accumulated without any excretion, at least within the concentrations studied. It was also proved that under the estuarine conditions tested here, P. vannamei juveniles showed capacity to act as a bioindicator for cadmium.