Martin-Dominguez A.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Lara-Sanchez A.,Buckman Laboratories S.A. de C.V. |
Hansen-Hansen A.M.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Environmental Science and Pollution Research | Year: 2016
Humic substances (HS), a broad category of organic compounds and a major constituent of soil, are responsible for serious problems during water purification processes. In particular, HS react with chlorine during disinfection processes to produce a variety of organochlorine compounds such as trihalomethanes (THMs), which are potentially carcinogenic to humans. The use of ozone as a disinfection method represents a potential solution to this problem; however, HS that are not completely oxidized may form by-products more reactive than the original molecules. The structural changes of HS during oxidation with ozone were evaluated through a replicated 22 design, where concentrations of 5 and 30 mg/L of two commercial HS (Aldrich and Fluka) were ozonized over different time intervals (0, 10, and 20 min). The ozone-treated HS were titrated with acid and base solutions, and the shifts of the slopes were then analyzed and finally related to the ionic alterations of the HS. The Aldrich HS (AHS) showed only protonated functional groups; the Fluka HS (FHS) showed only ionized groups; and in both cases, the amount of functional groups increased with increasing ozonation. For AHS and FHA, respectively, the maximum ozone exposure time (20 min) and the highest concentration of HS (30 mg/L) produced the greatest reductions in total organic carbon (TOC) (39 and 34 %), UV254 (50 and 60.8 %), and color (16.4 and 19.6 %). As for aromaticity, AHS showed removals of 39.6 % (from a starting concentration of 5 mg/L) and 17.2 % (from a starting concentration of 30 mg/L). FHS showed the opposite effect, with removals of 33.3 % (starting at 5 mg/L) and 40.1 % (starting at 30 mg/L). In this study, the structural changes of HS submitted to ozonation were inferred in a relatively quick and easy way by using a conductometric titration, thus demonstrating the applicability of the technique. © 2016 Springer-Verlag Berlin Heidelberg
Hansen A.M.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Gay D.A.,University of Illinois at Urbana - Champaign
Environmental Science and Pollution Research | Year: 2013
We provide a longer-term record of Hg wet deposition at two tropical latitude monitoring sites in Mexico, selected to provide regionally representative data. Weekly wet deposition samples were collected over 2 years, from September 2003 to November 2005. Based on this data set, we discuss the magnitude and seasonal variation of Hg in wet deposition and compare the results to other measurement sites and to several model estimates. With precipitation-weighted mean (PWM) concentrations of 8.2 and 7.9 ng L-1, respectively, during the sampling period from Sep 30 2003 to Oct 11 2005, and median weekly concentrations of 9.4 ± 1 ng L-1 for both sites, the wet Hg concentrations and deposition at HD01 were much lower than those observed at the US Gulf Coast MDN sites while the wet Hg deposition at OA02 was much lower than most MDN sites, but somewhat similar to US MDN sites along the Pacific Coast. Based on the limited available data, we conclude that the approximately 30 % higher average precipitation at HD01 and roughly equal PWM concentrations lead to the higher deposition at HD01 versus OA02. We believe that these observations may offer scientists and modelers additional understanding of the depositional fluxes in the lower latitudes of North America. © 2013 Springer-Verlag Berlin Heidelberg.
Soares D.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Murillo-Licea D.,Research Center y Estudios Superiores en Antropologia Social
Cuadernos de Desarrollo Rural | Year: 2013
The aim of this paper is to contribute to the reflection on the link between disaster risk management and gender equity. It is presented a case study on perceptions about climate change and institutional abilities regarding risk management in four locations of the state of Yucatan, Mexico. In order to know the local social perceptions, surveys and interviews were administered to key informants, and the results account for the existence of serious problems in municipal institutions in charge of both disaster risk management and the promotion of processes to generate greater gender equality. Additionally, a lack of knowledge about the factors that cause climate change was recorded.
Wolaver B.D.,University of Texas at Austin |
Crossey L.J.,University of New Mexico |
Karlstrom K.E.,University of New Mexico |
Banner J.L.,University of Texas at Austin |
And 3 more authors.
Geosphere | Year: 2013
He, C, and Sr isotopes are used to infer spring sources in a water-stressed area. Spring-water origins and pathways in the Cuatrociénegas Basin are revealed by linking structure and geochemistry via regionally extensive fault networks. This study presents the first dissolved noble gas and He isotopic data from northeastern Mexico. Basementinvolved faults with complex reactivation histories are important in northeastern Mexico tectonics and affect hydrogeologic systems. The importance of faults as conduits for northeastern Mexico volcanism is recognized, but connections between faulting and the hydrogeologic system have not been extensively investigated. This research tests the hypothesis that Cuatrociénegas Basin springs are divided into two general classes based upon discharge properties: (1) regional carbonate aquifer discharge (mesogenic) mixed with contributions from deeply sourced (endogenic) fluids containing 3He and CO2 from the mantle that ascend along basement-involved faults; and (2) carbonate aquifer discharge mixed with locally recharged (epigenic) mountain precipi tation. Carbonate and/or evaporite dissolution is indicated by Ca-SO4 hydrochemical facies. He isotopes range from 0.89 to 1.85 RA (RA is the 3He/4He of air, 1.4 × 10-6) and have minimal 3H, from which it is inferred that basement-involved faults permit degassing of mantle-derived He (to 23% of the total He) and CO2 (pCO2 10-1 atm). Mantle degassing is compatible with the thinned North American lithosphere, as shown in tomographic images. Sr isotopes in both Cuatrociénegas Basin springs and spring-deposited travertine (87Sr/86Sr = 0.707428-0.707468) indicate that carbonate rocks of the regional Cupido aquifer (87Sr/86Sr = 0.7072-0.7076) are the main source of Sr. Rock-water interactions with mafic volcanic rocks (87Sr/86Sr = 0.70333-0.70359) are not inferred to be an important process. Groundwater-dissolved inorganic C origins are modeled using major elements and C isotopes. C isotope data show that ~30% ± 22% of CO2 in spring water is derived from dissolution of aquifer carbonates (Ccarb = 30%), 24% ± 16% is from soil gas and other organic sources (Corg = 24%), and 46% ± 33% is from deep sources [Cendo (endogenic crust and mantle) = 46%]. This study demonstrates the presence of mantlederived 3He and deeply sourced CO2 that ascend along basement-penetrating faults and mix with Cupido aquifer groundwater before discharging in Cuatrociénegas Basin springs. © 2013 Geological Society of America.
Ramirez-Camperos A.M.,National Autonomous University of Mexico |
Rodriguez-Padilla V.,National Autonomous University of Mexico |
Guido-Aldana P.A.,Instituto Mexicano Of Tecnologia Del Agua Imta
Energy Policy | Year: 2013
This article analyses the cause-effect relation of the structural reform in the Mexican electricity sector, called the Public Electricity Service Act, from 1992 to 2009. One of the main arguments of the reform is to attract private investment in order to reduce the financial load of the government in infrastructure for the development of the National Electric Power System by means of six modalities (Power Self-Supply, Cogeneration, Small Power Production, Independent Power Production, Power Export and Power Import). The article presents the global context of reforms adopted in 1990. The major policies and events are presented in chronological order (before and after reform). In addition, it analyses the new institutional framework, the evolution of modalities, technologies of electricity generation and tariffs. The main conclusion is that the result of reform could be considered a partial progress. The Independent Power Production modality shows greater participation, while Power Self-Supply and Cogeneration are lower. The subsidy policy is maintained. Progress is needed in policies and strengthening, and also in updating regulatory and normative frameworks. © 2013 Elsevier Ltd.
Robles I.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Palacio A.,National Autonomous University of Mexico |
Rodriguez A.,National Autonomous University of Mexico
Dam Protections against Overtopping and Accidental Leakage - Proceedings of the 1st International Seminar on Dam Protections Against Overtopping and Accidental Leakage | Year: 2015
In this paper the design of a structure to dissipate energy in the spillways was analyzed as an alternative to reduce the destructive effects of water at high speed. Work on energy dissipation are critical elements in the construction of hydraulic structures, these have been developed based on the experience and wealth of knowledge in the field, however, the design of these structures involves laboratory studies, collection prototype field data, statistics, among others. In order to assist in this effort to collect information useful in the design of structures of energy dissipation information current work is presented with information obtained from laboratory data relevant parameters of structures including willing obstacles especially to achieve this objective. The main objective of the study is to have design elements to build a structure of energy dissipation decreases the undesirable effects present in the spillways flow with a sufficiently quieted to avoid structural damage. This was done with the support of a laboratory physical model provided for this purpose. For testing of the physical model α angle was set in one position and the following dimensionless parameters were varied: Lh/Lv, d/D, where D is the maximum diameter of the tests performed. Also the velocity profiles of all testswere measured at 0.12mfrom the point of supply to the water structure in the physical scale model. There are evidences that the variable that dominates the energy dissipation in these structures is the change in diameter of the cylindrical obstructions. © 2015 Taylor & Francis Group, London.
PubMed | Instituto Mexicano Of Tecnologia Del Agua Imta and National Autonomous University of Mexico
Type: Journal Article | Journal: Environmental monitoring and assessment | Year: 2016
The spatial and temporal variation of water quality in the urban area of the Puebla Valley aquifer was evaluated using historical and present data obtained during this investigation. The current study assessed water quality based on the Water Quality Index developed by the Canadian Council of Ministers of the Environment (CCME-WQI), which provides a mathematical framework to evaluate the quality of water in combination with a set of conditions representing quality criteria, or limits. This index is flexible regarding the type and number of variables used by the evaluation given that the variables of interest are selected according to the characteristics and objectives of development, conservation and compliance with regulations. The CCME-WQI was calculated using several variables that assess the main use of the wells in the urban area that is public supply, according to criteria for human use and consumption established by Mexican law and international standards proposed by the World Health Organization. The assessment of the index shows a gradual deterioration in the quality of the aquifer over time, as the amount of wells with excellent quality have decreased and those with lower index values (poor quality) have increased throughout the urban area of the Puebla Valley aquifer. The parameters affecting groundwater quality are: total dissolved solids, sulfate, calcium, magnesium and total hardness.
Ojeda-Bustamante W.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Sifuentes-Ibarra E.,INIFAP CIRNO Campo Experimental Valle del Fuerte |
Iiguez-Covarrubias M.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Montero-Martinez M.J.,Instituto Mexicano Of Tecnologia Del Agua Imta
Agrociencia | Year: 2011
Due to the impact of climate change, the modification of water cycle processes, mainly evapotranspiration and precipitation, will have a radical effect on irrigation water demands and management of irrigation systems. Climate change projections indicate an increase in air temperature, with spatial and temporal variability. In this study, we analyzed the expected impact of climate change on water demands and crop development, by using climate change projections for the moderate-medium emissions scenario (A1B), for the conditions of Irrigation District 075, Río Fuerte, Sinaloa, México. It was estimated that by the end of the century, the annual increase of reference evapotranspiration will be 10 % compared to current values. Water demand for crops will be reduced by 13 % for the Autumn-Winter season and 6 % for the Spring-Summer season, and it will increase by 7 % for the Perennial season by the end of the century. This can be attributed to the fact that although reference evapotranspiration will increase, the greatest impact from a temperature increase will be in shortening the growing season of annual crops. Therefore, it is necessary to implement adaptation actions: in the first place, using longer season cultivars than those cultivated today, with resistance to thermal stress; and in the second place, compacting the planting season toward the colder months.
Garzon-Zuniga M.A.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Sandoval-Villasana A.M.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Moeller-Chavez G.E.,Instituto Mexicano Of Tecnologia Del Agua Imta
Water Environment Research | Year: 2011
Acid Orange 24 (AO24) dye was degraded in a trickling biofilter packed with peat and wood chips and inoculated with biomass from a petrochemical industry wastewater system. Different operating strategies were tested; in the first stage, two biofilters were operated independently - one non-aerated biofilter (passive) and the other with aeration - subsequently, the systems were operated serially, and effluent from the non-aerated biofilter was fed to the biofilter with aeration. This treatment train was used to test three different filtration velocities - 0.141, 0.282, and 0.423 m/d. The results show that, when operating the systems with a dye charge of 0.035 kg AO24 m 2/d and treating the effluent in a single step, good removal efficiencies of AO24 (95 and 89%), COD (63 and 53%), and acute toxicity (63 and 78%) were obtained in both biofilters (with and without air), although mutagenic and potentially carcinogenic intermediary compounds were not removed, because genotoxicity exhibits values higher than 2.0 units for the mutation rate. When using the nonaerated biofilter/aerated biofilter treatment train, it is possible to treat a dye charge 3 times greater (0.106 kg AO24 m 2/d) and efficiently remove 98% AO24, 76% COD, 100% acute toxicity, and 100% genotoxicity, which indicates that, with this biological system, an advanced degree of biotransformation and mineralization of the azo dye AO24 is achieved.
Marquez-Pacheco H.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Hansen A.M.,Instituto Mexicano Of Tecnologia Del Agua Imta |
Falcon-Rojas A.,Instituto Mexicano Of Tecnologia Del Agua Imta
Environmental Science and Pollution Research | Year: 2013
Water in lakes and reservoirs accumulate phosphorous (P) from both internal and external loads. The external P load (EPL) coming from the watershed is considered to be the main cause of eutrophication of water bodies, and control strategies therefore focus on its reduction. However, algae blooms and anoxic conditions often continue even after EPL have been controlled, being the internal P load (IPL) originating from the sediment the main sources of P. To assess the efficiency of the adsorbent Phoslock (a modified bentonite) in controlling P concentrations in water and immobilize releasable P in sediments, mesocosm trials were carried out in a eutrophied reservoir and a model was described and applied that determines the amount of adsorbent and the application frequency necessary to control P concentrations in a eutrophied reservoir. The mesocosm trials confirm that Phoslock reduced P concentrations to or below the limits that define water in mesotrophic state, in approximately 2 weeks. The modeling results suggest that periodic reapplications of the adsorbent are required, unless EPL is reduced by 36 %, which allows the P concentrations in the water column to be constant. Such reduction in EPL would allow future applications of the adsorbent to be required only for control of IPL. The developed model allows planning remediation actions by determining quantities and frequencies for application of adsorbents for P control in eutrophied lakes and reservoirs. © 2013 Springer-Verlag Berlin Heidelberg.