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 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
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.