RESUMEN
Sanitary landfills are considered one of the main sources of contamination of water resources due to the generation of leachate with a high content of dissolved organic matter (DOM), inorganic material, and toxic elements. This study aimed to determine the influence of leachate on the physicochemical quality and hydrogeochemical processes which determine the chemical composition of groundwater in an area near a municipal sanitary landfill site. In situ parameters (pH, temperature, electrical conductivity, dissolved oxygen, ORP), physicochemical parameters (HCO3-, PO43-, Cl-, NO3-, SO42-, NH4+, Ca2+, Mg2+, Na+, K+), and dissolved organic matter were analyzed. The content of dissolved organic matter (DOM) was determined by 3D fluorescence microscopy. The presence of Cl-, NO3-, NH4+, PO43-, BOD, and COD indicated the presence of contamination. The significant correlation between NO3- and PO43- ions (r = 0.940) and DOM of anthropogenic origin in the 3D fluorescence spectra confirm that its presence in the water is associated with the municipal landfill site in question. The type of water in the area is Mg-HCO3, with a tendency to Na-HCO3 and Na-SO+-Cl. The water-rock interaction process predominates in the chemical composition of water; however, significant correlations between Na+ and Ca2+ (r = 0.876), and between K+ and Mg2+ (r = 0.980) showed that an ion exchange process had taken place. Likewise, there is enrichment by HCO3- and SO42- ions due to the mineralization of the organic matter from the leachate. The groundwater quality that supplies the study area is being affected by leachate infiltration from the sanitary landfill.
Asunto(s)
Agua Subterránea , Contaminantes Químicos del Agua , Monitoreo del Ambiente , Instalaciones de Eliminación de Residuos , Contaminantes Químicos del Agua/análisis , Recursos HídricosRESUMEN
The use of wastewater for agricultural irrigation is a common practice worldwide; long-term use of wastewater can have adverse effects, such as the migration of the anthropogenic dissolved organic matter into the aquifer. Three-dimensional fluorescence spectroscopy (EEM) was used to investigate the characteristics of dissolved organic matter (DOM) in groundwater and irrigation wastewater, to establish the effect of intensive irrigation on the water quality from the aquifer that underlies the area. The fluorescence spectra showed the presence of humic and fulvic acids and anthropogenic organic compounds similar to aromatic proteins and soluble microbial products in wastewater resources. The significant fraction of DOM in groundwater samples are aromatic proteins and soluble microbial products, identical to wastewater. Chlorides and nitrate ion concentrations suggest a local flow system. High levels of TDS are associated with intensive irrigation with residual water and the return irrigation associated with a gradual increase in salts of CO32-, NO3-, HCO3-, Cl-, and SO42-. The anthropogenic DOM is a useful indicator of water quality management in groundwater based on origin tracking of DOM and changes in organic pollutants. Fluorescence spectroscopy can be used to investigate groundwater pollution characteristics and monitor DOM dynamics in groundwater.
Asunto(s)
Agua Subterránea , Contaminantes Químicos del Agua , Monitoreo del Ambiente , Compuestos Orgánicos , Aguas Residuales , Contaminantes Químicos del Agua/análisis , Calidad del AguaRESUMEN
The chemical composition of groundwater is a product of the evolution and transformation of major ions, which come from natural hydrogeochemical processes or from anthropogenic interference. The objective of this study was to identify the hydrogeochemical processes and the influence of anthropogenic activity on the variation of chemical composition in Toluca Valley groundwater. The type of water in the zone is fundamentally Mg-Ca-HCO3. Three groups with different evolutionary tendencies were identified: one within a local recharge zone and two others in an intermediate region with anthropic activity. The latter, which show contamination by inorganic matter (fertilizers) and organic matter (urban or industrial wastewater). The content of N-NO3- (0.024-0.219 mEq L-1), N-NH4+ (0-0.022 mEq L-1), Porg (0.03-1.02 mEq L-1) and PO43- (0.0-0.28 mEq L-1) indicated contamination coming from inorganic and organic matter. These chemical compounds were identified by way of a 3D fluorescence technique. The results of this study demonstrate that the main processes that affect and control the chemical composition of the water in the Toluca Valley aquifer are weathering of silicates, the ion exchange and a mixture process generated by a source of anthropic contamination.
Asunto(s)
Monitoreo del Ambiente/métodos , Fertilizantes/análisis , Agua Subterránea/química , Aguas Residuales/análisis , Contaminantes Químicos del Agua/análisis , Pozos de Agua , México , Aguas Residuales/química , Tiempo (Meteorología)RESUMEN
The fluoride content in groundwater varies depending on geological configuration. Fluoride problems tend to occur in places where these minerals are most abundant in rocks. The objective of the present work was to synthesize four biopolymers based on chitosan-polyvinyl alcohol (Ch-PVA) cross-linked with sodium tripolyphosphate pentabasic (TPP) and ethylene glycol diglycidyl ether (EGDE) and determine their ability to remove fluoride from water. The characterization of the Ch-PVA beads was performed by way of Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The percentage of humidity and the point of zero charge were determined. The Ch-PVA beads showed a surface area of 63.87 m2 g-1, a pore size of 7.6 nm, a point of zero charge of 7.4, and 98.6% humidity. The kinetic adsorption study was adjusted to the pseudo-second-order model and the adsorption equilibrium data were adjusted to the Freundlich adsorption isotherm, showing a maximum fluoride adsorption capacity of 12.64 mg.g-1 at pH 7 and 30 °C, for the beads of Ch-PVA-NaOH-TPP. According to the thermodynamic parameters: -∆Go, +∆Ho and -∆So, fluoride adsorption is spontaneous, endothermic in nature and there is no random energy change in the solid/liquid interface during the adsorption process.
Asunto(s)
Quitosano/análogos & derivados , Fluoruros/aislamiento & purificación , Alcohol Polivinílico/química , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Reactivos de Enlaces Cruzados/química , Resinas Epoxi/química , Polifosfatos/química , Termodinámica , Agua/análisisRESUMEN
Anthropogenic activities can deteriorate the quality of groundwater destined for human use and consumption due to the fact that human activities cause changes in groundwater chemistry. The changes are induced by chemical species coming from industrial waste, which interacts with rocks and minerals. These trigger agents (phosphorus and nitrogen nutrients) which can incorporate trace elements (As, Fe, Mn, Pb, Cd, Ni, Zn). The main objective of the present work was to study the phosphate ions' and nitrogenous species' effects on the incorporation of trace elements into groundwater used for human consumption and to determine the physicochemical processes that participate in the incorporation of trace elements. The physicochemical analysis and elemental analysis by ICP of the groundwater that supplies the study area showed that the phosphorus (P) activity contributes in the incorporation of trace elements into the water. Significant correlations between the activities of P and Fe (0.516), Mn (0.553), Pb (0.756), and As (- 0.747) as well as the correlation of NH4+ with As indicate that the presence of chemical species such as PO43- (2.50-32.20 mg L-1), NO3- (0.89-30.80 mg L-1), and NH4+ (0.2-12.70 mg L-1) are triggering agents that favor the dissolution and mobility of As (0.014-0.020 mg L-1), Fe (0.020-1.14 mg L-1), Mn (0.007-0.254 mg L-1), Ni (0.002-0.0141 mg L-1), Zn (0.009-0.459 mg L-1), and Pb (0.009-0.0170 mg L-1), species with adverse health effects because they are considered carcinogenic. Adequate control of the nitrogenous and phosphated material prevents the dissolution and mobility of trace elements into the water.