In this paper six fossil forms of Chrysophycean stomatocysts are described. The material was collected from sedimentary pyrite embedded in well-laminated organic-rich limestone of the Upper Cretaceous Agua Nueva Forma...In this paper six fossil forms of Chrysophycean stomatocysts are described. The material was collected from sedimentary pyrite embedded in well-laminated organic-rich limestone of the Upper Cretaceous Agua Nueva Formation at the locality of Xilitla, Central Mexico. The stomatocysts are represented by two spherical specimens with smooth surfaces lacking of ornamentation, three ovoid forms with rugose textures, one of them exposing presence of pore without collar, and one spherical specimen showing rugose texture and the presence of two short and rounded projections. The specimens here described showed affinity with some stomatocysts morphotypes described for brackish and fresh water, but not for known marine specimens. The presence of these microfossils in the Agua Nueva Formation represents the first formal description of fossil stomatocysts in Upper Cretaceous sedimentary pyrite in Mexico. The occurrence of both micro (planktonic foraminifera, calcispheres, radiolarians) and macrobiota (ammonites, inoceramid bivalves and fishes) and the presence of the specimens in sedimentary pyrite suggest that the stomatocysts were preserved under oxygen-deficiency conditions in a low energy environment. This event could have occurred in open marine waters in the Tampico-Misantla basin (Central Mexico) during the late Cenomanian throughout the early Turonian.展开更多
The aim of this research paper was to identify whether the water quality had been influenced either by the natural environment or by anthropogenic activities or both in the municipality of Linares, the second largest ...The aim of this research paper was to identify whether the water quality had been influenced either by the natural environment or by anthropogenic activities or both in the municipality of Linares, the second largest city of the State of Nuevo Leon, NE Mexico. The superficial water (Pablillo River) and the groundwater quality (from a fractured and a porous aquifers hydraulically interconnected) were determined by comparing their chemical composition with maximum permissible limits for water consumption and irrigation use. A hydrogeochemical modeling was performed to identify the distribution of aqueous species responsible for the presence of some dissolved or precipitated mineral species, as well as an identification of geochemical factors responsible of superficial and groundwater quality. A canonical correspondence analysis was allowed to determine if the natural environment and/or anthropogenic activities were responsible for water quality. The parameters analysed in both aquifers, as well as in the Pablillo River, were total solids, suspended solids, nitrate, and chloride;barium and mercury were present in both aquifers. As a natural influence, the predominant mineral species are as following: under-saturated anhydrite (porous aquifer), over-saturated aragonite, calcite, dolomite, and gypsum (both aquifers and Pablillo River), barite and whiterite (only in fractured aquifer). The geochemical factors responsible for natural contamination were rock dominance (fractured aquifer), and evaporation dominance (porous aquifer, Pablillo River). On the other hand, anthropogenic activities such as changes in soil use and the presence of point (old municipal landfill, pig farms, barite deposit), and diffuse (agricultural areas, septic tanks and latrines) pollution sources had influence in the presence of contaminants such as total and fecal coliforms, nitrates, chlorides, mercury and barium. Several control and remediation strategies should be taken into account to prevent this pollution in the future.展开更多
This study consisted of a geochemical analysis of the Dos Carlos tailings’ deposit located in the Mining District of Pachuca-Real del Monte in the state of Hidalgo, Central Mexico. The goal of the study was to determ...This study consisted of a geochemical analysis of the Dos Carlos tailings’ deposit located in the Mining District of Pachuca-Real del Monte in the state of Hidalgo, Central Mexico. The goal of the study was to determine the potential effects of this deposit on the environment and health of the population of the metropolitan area of Pachuca. Sampling was conducted from the top to the base of two raised sections at opposite ends of the deposit, and macroscopic features (profiles A and B) of these deposits were evaluated. Subsequently, mineralogical analyses of the collected samples were performed using X-ray diffraction and physico-chemical analysis of the leachates. The results were compared with the maximum permissible limits established by different national and international standards for drinking water and hazardous waste. In addition, geochemical modeling was conducted using PHREEQC to calculate the distribution of aqueous species, ionic activities and saturation indices.(For more information, please refer to the PDF.)展开更多
基金Programa al Mejoramiento del Profesorado(PROMEP:Project No.72636363)the Consejo Nacional de Ciencia y Tecnologia(CONACYT:Project No.83849)for providing finantial support for fieldwork and collecting data at the locality of Xilitla.
文摘In this paper six fossil forms of Chrysophycean stomatocysts are described. The material was collected from sedimentary pyrite embedded in well-laminated organic-rich limestone of the Upper Cretaceous Agua Nueva Formation at the locality of Xilitla, Central Mexico. The stomatocysts are represented by two spherical specimens with smooth surfaces lacking of ornamentation, three ovoid forms with rugose textures, one of them exposing presence of pore without collar, and one spherical specimen showing rugose texture and the presence of two short and rounded projections. The specimens here described showed affinity with some stomatocysts morphotypes described for brackish and fresh water, but not for known marine specimens. The presence of these microfossils in the Agua Nueva Formation represents the first formal description of fossil stomatocysts in Upper Cretaceous sedimentary pyrite in Mexico. The occurrence of both micro (planktonic foraminifera, calcispheres, radiolarians) and macrobiota (ammonites, inoceramid bivalves and fishes) and the presence of the specimens in sedimentary pyrite suggest that the stomatocysts were preserved under oxygen-deficiency conditions in a low energy environment. This event could have occurred in open marine waters in the Tampico-Misantla basin (Central Mexico) during the late Cenomanian throughout the early Turonian.
基金the National Council of Science and Technology(Consejo Nacional de Ciencia y Tecnología,Co-nacyt)for the scholarship number 159971to the projects Conacyt-Conafor CO1 6231,Paicyt and Promep-2009-2011 for financial support.
文摘The aim of this research paper was to identify whether the water quality had been influenced either by the natural environment or by anthropogenic activities or both in the municipality of Linares, the second largest city of the State of Nuevo Leon, NE Mexico. The superficial water (Pablillo River) and the groundwater quality (from a fractured and a porous aquifers hydraulically interconnected) were determined by comparing their chemical composition with maximum permissible limits for water consumption and irrigation use. A hydrogeochemical modeling was performed to identify the distribution of aqueous species responsible for the presence of some dissolved or precipitated mineral species, as well as an identification of geochemical factors responsible of superficial and groundwater quality. A canonical correspondence analysis was allowed to determine if the natural environment and/or anthropogenic activities were responsible for water quality. The parameters analysed in both aquifers, as well as in the Pablillo River, were total solids, suspended solids, nitrate, and chloride;barium and mercury were present in both aquifers. As a natural influence, the predominant mineral species are as following: under-saturated anhydrite (porous aquifer), over-saturated aragonite, calcite, dolomite, and gypsum (both aquifers and Pablillo River), barite and whiterite (only in fractured aquifer). The geochemical factors responsible for natural contamination were rock dominance (fractured aquifer), and evaporation dominance (porous aquifer, Pablillo River). On the other hand, anthropogenic activities such as changes in soil use and the presence of point (old municipal landfill, pig farms, barite deposit), and diffuse (agricultural areas, septic tanks and latrines) pollution sources had influence in the presence of contaminants such as total and fecal coliforms, nitrates, chlorides, mercury and barium. Several control and remediation strategies should be taken into account to prevent this pollution in the future.
基金the Faculty Improvement Program(PROMEP)for financing through the project F-PROMEP-38/Rev-03,SEP-23-005.
文摘This study consisted of a geochemical analysis of the Dos Carlos tailings’ deposit located in the Mining District of Pachuca-Real del Monte in the state of Hidalgo, Central Mexico. The goal of the study was to determine the potential effects of this deposit on the environment and health of the population of the metropolitan area of Pachuca. Sampling was conducted from the top to the base of two raised sections at opposite ends of the deposit, and macroscopic features (profiles A and B) of these deposits were evaluated. Subsequently, mineralogical analyses of the collected samples were performed using X-ray diffraction and physico-chemical analysis of the leachates. The results were compared with the maximum permissible limits established by different national and international standards for drinking water and hazardous waste. In addition, geochemical modeling was conducted using PHREEQC to calculate the distribution of aqueous species, ionic activities and saturation indices.(For more information, please refer to the PDF.)
