Rodriguez-Salazar M.T.,National Autonomous University of Mexico |
Bermea O.M.,National Autonomous University of Mexico |
Hernandez-Alvarez E.,National Autonomous University of Mexico |
Garcia-Arreola M.E.,Autonomous University of San Luis Potosi |
Ortuno-Arzate M.T.,National Research Center y Capacitacion Ambiental
Geofisica Internacional | Year: 2010
This work reports a method for the precise and accurate determination of Pb isotope composition in soils and geological matrices by ICP-QMS. Three reference materials (AGV-2, SRM 2709 and JSO-1) were repeatedly measured, using ICP-QMS instruments in order to assess the quality of this analytical procedure. Mass discrimination was evaluated for Pb/Pb with Pb isotope reference material NIST SRM 981, and the correction applied to the above mentioned reference materials to achieve good accuracy of the analytical methodology. An internal standardization using 205Tl was employed to avoid instrumental drift. The measured isotope compositions of all analyzed reference material were comparable with the reported (JSO-1 and SRM 2709) and certified values (AGV-2). The accuracy results agreed in average within 0.002% for 207Pb/204Pb and 0.825% for 207Pb/206Pb. These data corroborate that ICP-QMS results to be reliable in terms of accuracy and precision, for the determination of the Pb isotopic compositions in soils and geological matrices.
Ortiz I.,Metropolitan Autonomous University |
Velasco A.,National Research Center y Capacitacion Ambiental |
Le Borgne S.,Metropolitan Autonomous University |
Revah S.,Metropolitan Autonomous University
Biodegradation | Year: 2013
Stimulation of native microbial populations in soil by the addition of small amounts of secondary carbon sources (cosubstrates) and its effect on the degradation and theoretical mineralization of DDT [l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane] and its main metabolites, DDD and DDE, were evaluated. Microbial activity in soil polluted with DDT, DDE and DDD was increased by the presence of phenol, hexane and toluene as cosubstrates. The consumption of DDT was increased from 23 % in a control (without cosubstrate) to 67, 59 and 56 % in the presence of phenol, hexane and toluene, respectively. DDE was completely removed in all cases, and DDD removal was enhanced from 67 % in the control to ~86 % with all substrates tested, except for acetic acid and glucose substrates. In the latter cases, DDD removal was either inhibited or unchanged from the control. The optimal amount of added cosubstrate was observed to be between 0. 64 and 2. 6 mg C g-1 drysoil. The CO2 produced was higher than the theoretical amount for complete cosubstrate mineralization indicating possible mineralization of DDT and its metabolites. Bacterial communities were evaluated by denaturing gradient gel electrophoresis, which indicated that native soil and the untreated control presented a low bacterial diversity. The detected bacteria were related to soil microorganisms and microorganisms with known biodegradative potential. In the presence of toluene a bacterium related to Azoarcus, a genus that includes species capable of growing at the expense of aromatic compounds such as toluene and halobenzoates under denitrifying conditions, was detected. © 2012 Springer Science+Business Media B.V.
Torres-Ramos Y.D.,Instituto Nacional Of Perinatologia |
Torres-Ramos Y.D.,National Polytechnic Institute of Mexico |
Montoya-Estrada A.,Instituto Nacional Of Perinatologia |
Guzman-Grenfell A.M.,Instituto Nacional Of Perinatologia |
And 6 more authors.
Frontiers in Bioscience - Elite | Year: 2011
Particulate matters (PM) produce adverse effects on the respiratory system and cause COPD. These effects are thought to involve intrinsic generation of ROS which are present in ambient PM (transition metals and aromatic organic compounds). Here, we examined the chemical composition and ultra-microscopic structure of PM2. 5. The effect of this PM was studied in red blood cell (RBC) membranes (ghosts) from healthy volunteers (n = 11) and COPD patients (n = 43). These effects were compared with that produced by a Fenton metal-catalytic ROS generator. Oxidative biomarkers and cell damage were singificantly increased in presence of PM2. 5 or ROS generator in RBC of COPD patients as compared with those in cells from healthy volunteers. In contrast, total SH groups, band 3 phospho-tyrosine phosphatase (PTPase) and glucose-6 phosphate dehydrogenase (G6PD) activities were all diminished in cells from COPD patients. In conclusion, PM2. 5 increases damage to RBCs from COPD patients, decreases the activity of PTPase and G6PD, and alters the function of the anionic exchanger (AE1) and the antioxidant response by decreasing SH groups.
Aburto-Medina A.,Metropolitan Autonomous University |
Castillo D.,Metropolitan Autonomous University |
Ortiz I.,Metropolitan Autonomous University |
Hernandez E.,National Research Center y Capacitacion Ambiental |
And 2 more authors.
Revista Internacional de Contaminacion Ambiental | Year: 2015
Wetlands pollution is of great concern given their importance to conservation and as water and food sources for the local population. Therefore, microbial and chemical investigations were carried out on the Lerma (Chimaliapan) and Almoloya del Río (Chiconahuapan; both Ramsar sites) wetland samples in Mexico for risk assessment purposes. 16S rRNA-based clone library analyses showed the prevalence of Enterobacteriaceae, specifically the genus Shigella and E. coli species in both wetlands. While faecal coliform levels in both wetlands were below the accepted limit, higher total coliform counts (> 2400 MPN) were observed in ~ 40% of the sampled sites at Lerma. Other microorganisms detected included organisms similar to those obtained from hydrocarbon-contaminated environments with alkanes and poly-aromatic hydrocarbons being detected in the sediments. Detected metals were below United States Environmental Protection Agency (USEPA) limits, decreasing in the sequence: Al > Fe > Mn >V> Zn > Pb > Ni > Cr > Cu > Co > Tl > As > Be (except Cr at Almoloya). However, Al concentrations were significantly above the permissible limits (2700 mg/kg) of the National Oceanic and Atmospheric Administration of the United States in both wetlands. This study therefore demonstrates that increased health risks and potential for metal biomagnification by edible species could be associated with the use of wetland water resources. © 2015, Centro de Ciencias de la Atmosfera, UNAM. All rights reserved.