The present study is conducted with the purpose of determining the chemical characteristics of groundwater that supplies 16 wells in the state of Coahuila, which are used for different human activities. Sampling was c...The present study is conducted with the purpose of determining the chemical characteristics of groundwater that supplies 16 wells in the state of Coahuila, which are used for different human activities. Sampling was conducted in January 2011. For 56% of the fifteen wells tested, analysis did not detect the presence of aluminum;however, wells 2, 3, 6, 8 and 13 had concentrations above the permissible limit established by the Mexican standard NOM-127-SSA1-1994. For cadmium, only the well 3 was above the Norm. Meanwhile, iron was above the permissible limit in eight wells (2, 4, 5, 6, 9, 12, 13 and 15). Lead exceeded the limit in wells 6, 7, 9, 10, 11 and 12. In general, for the rest of the parameters listed in the Norm, values were below allowable limits. By using Piper diagrams, it was observed that in general, the waters tested showed characteristic calcium bicarbonate. By establishing a matrix of correlations between chemical parameters, it was observed that the highest significant correlations occurred among carbonate hardness, calcium, lead and total alkalinity, with r2 values greater than 0.82. Also, high correlations were found between some metal species, suggesting a common origin. The allowed Principal Component Analysis and Cluster Analysis establish the associations between all analyzed physicochemical parameters, and they also determine the wells with similar characteristics.展开更多
The present study was carried out between May and June 2012 in the city of Cuernavaca, Mexico. During this time the average ambient temperatures were about 25°C, suggesting the formation of secondary aerosols, co...The present study was carried out between May and June 2012 in the city of Cuernavaca, Mexico. During this time the average ambient temperatures were about 25°C, suggesting the formation of secondary aerosols, consisting mainly of ammonium and sulfate. The average PM2.5 concentration was 37 μg·m-3 for the entire urban area and there were only two days which exceeded the limit established by the official standards for periods of 24 h. The most abundant ionic species associated with PM2.5 were sulfates (3634.82 ng·m-3, average) and ammonium (1709.53 ng·m-3, average). The ratio estimated between total anions and total cations indicated that the concentration of total anions was 1.94 times total cations. The contribution percentage of the ionic species associated with PM2.5 revealed that 76% of the PM2.5 is sulfates and ammonium. The ion balance made for the urban area of Cuernavaca indicated that during the study period, the aerosols showed alkaline characteristics;that is to say the concentration of anions was not sufficient to neutralize the cations, specifically ammonia (m = 0.060). Finally, wind fields showed that during the study the winds came in 50% from the south west, followed by 25% from east and 12.5% of the south east, which in part allowed transport of contaminants into the portion of the city, where the AUSM campus site was located.展开更多
文摘The present study is conducted with the purpose of determining the chemical characteristics of groundwater that supplies 16 wells in the state of Coahuila, which are used for different human activities. Sampling was conducted in January 2011. For 56% of the fifteen wells tested, analysis did not detect the presence of aluminum;however, wells 2, 3, 6, 8 and 13 had concentrations above the permissible limit established by the Mexican standard NOM-127-SSA1-1994. For cadmium, only the well 3 was above the Norm. Meanwhile, iron was above the permissible limit in eight wells (2, 4, 5, 6, 9, 12, 13 and 15). Lead exceeded the limit in wells 6, 7, 9, 10, 11 and 12. In general, for the rest of the parameters listed in the Norm, values were below allowable limits. By using Piper diagrams, it was observed that in general, the waters tested showed characteristic calcium bicarbonate. By establishing a matrix of correlations between chemical parameters, it was observed that the highest significant correlations occurred among carbonate hardness, calcium, lead and total alkalinity, with r2 values greater than 0.82. Also, high correlations were found between some metal species, suggesting a common origin. The allowed Principal Component Analysis and Cluster Analysis establish the associations between all analyzed physicochemical parameters, and they also determine the wells with similar characteristics.
基金National Council for Science and Technology(CONACyT,for its acronym in English)for the financial support in this project.
文摘The present study was carried out between May and June 2012 in the city of Cuernavaca, Mexico. During this time the average ambient temperatures were about 25°C, suggesting the formation of secondary aerosols, consisting mainly of ammonium and sulfate. The average PM2.5 concentration was 37 μg·m-3 for the entire urban area and there were only two days which exceeded the limit established by the official standards for periods of 24 h. The most abundant ionic species associated with PM2.5 were sulfates (3634.82 ng·m-3, average) and ammonium (1709.53 ng·m-3, average). The ratio estimated between total anions and total cations indicated that the concentration of total anions was 1.94 times total cations. The contribution percentage of the ionic species associated with PM2.5 revealed that 76% of the PM2.5 is sulfates and ammonium. The ion balance made for the urban area of Cuernavaca indicated that during the study period, the aerosols showed alkaline characteristics;that is to say the concentration of anions was not sufficient to neutralize the cations, specifically ammonia (m = 0.060). Finally, wind fields showed that during the study the winds came in 50% from the south west, followed by 25% from east and 12.5% of the south east, which in part allowed transport of contaminants into the portion of the city, where the AUSM campus site was located.
