BIOMONITOREO ACTIVO CON Leskea angustata EN LA ZONA METROPOLITANA DEL VALLE DE TOLUCA

The main purpose of this research was to assess Cu, Zn, and Pb levels in the metropolitan area of the Toluca Valley (ZMVT, Spanish acronym) by active biomonitoring, using moss bags and Leskea angustata as bioindicators, as well as to determine whether phytoquelatins (PCs) are produced and if there is a correlation between PCs and glutathione (GHS) concentrations and the heavy metals present in moss. Ten monitoring locations were selected in which two moss bags were exposed to the ZMVT environment for six months. Heavy metals concentrations were determined using total reflection x-ray fluorescence (TRXF), whereas GHS and PCs were quantified by ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS). GHS and PCs concentration were measured before and after exposition, and the enrichment rate was also calculated. Results show enrichment rates between 2 and 30 for heavy metals and 116 and 569 for GHS. PCs concentrations were below the limit of detection. The order of total metal concentrations in the monitoring locations was: Tollocan > Reforma > San Mateo Atenco > Alameda > Aeropuerto > San Cristobal > Metepec > Ceboruco > Toluca Centro > Oxtotitlan. Overall, Tollocan, San Mateo Atenco, Alameda and Reforma were significantly different from other locations. GHS presented a concentration rate between 164 and 808 nM/g and had positive correlations (r = 0-8) with Cu, Zn and Pb; therefore, it is inferred that concentrations of the assessed heavy metals in this study are related to their direct induction. It can be concluded that GHS plays a major role in divalent metals bioaccumulation since it is an important detoxification mechanism in these organisms.