Arsenic and fluoride are elements known to cause human health problems and it has been documented that both elements are found in high concentrations in the Guadiana Valley aquifer, in the state of Durango, Mexico. Si...Arsenic and fluoride are elements known to cause human health problems and it has been documented that both elements are found in high concentrations in the Guadiana Valley aquifer, in the state of Durango, Mexico. Since underground water is the source for potable water bottling companies commercialized in Durango City;such high concentrations reduced the quality of bottled water for human consumption according to NOM-041-SSA1-1993. Legislation establishes a maximum permissible limit (MPL) of 0.7 mg/L for fluoride and 0.025 mg/L for arsenic. In this research the main objective was to evaluate the quality of bottled water expended in Durango City with respect to the well from which water is extracted. Findings showed that the highest fluoride concentration was 5.86 mg/L (8.4 times MPL), with 100% of sampled brands exceeding the MPL (range: 1.09 to 5.86 mg/L). On the other hand, for arsenic, the highest concentration was 0.076 mg/L (threefold), with 38% exceeding the MPL (range: 0.001 to 0.076 ppm). Statistical analysis showed significant differences only for fluoride, according to Fisher LSD (Least Significant Difference) test, with an F value of 14.5 at a p value of 0.0005. According to the comparison between the quantified concentrations in bottled water and groundwater, it was found that groundwater was subjected to treatment;however, although a significant decrease in fluoride and arsenic concentration was observed, the removal processes used were not efficient to meet set standards.展开更多
In this study</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> nineteen different brands of bottled mineral waters (7 brands local a...In this study</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> nineteen different brands of bottled mineral waters (7 brands local and 12 brands imported) were collected from supermarkets and independent food stores throughout Djibouti. The chemical composition mentioned on the labels of the nineteen bottled mineral waters ha</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> made the subject of a first verification by Ionic Balance Error (IBE). It was found out of the nineteen brands selected, 12 brands (2 brands local and 10 brands imported) had acceptable charge balance error. Correlation Analysis (CA), Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were used to analyze the data collected from the labels of bottled water. The obtained results showed that the 12 brands of studied waters can be grouped in 4 distinct classes with similar chemical characteristics. Two local and one imported brands have the same chemical composition but marketed under different names. It was observed that the chemical content local water brands w</span><span style="font-family:Verdana;">ere</span><span style="font-family:""><span style="font-family:Verdana;"> within the normal range prescribed by both WHO and USEPA except five imported water brands that have concentration values Ca, HCO</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">, Mg and SO</span><sub><span style="font-size:12px;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> beyond acceptable standards. Total hardness values classified most of the studied brands from moderate to very hard water.展开更多
Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the additio...Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the addition of radiogenic 87Sr produced by the beta decay of 87Rb with a half-life of 4.88 ± 0.05 Ga.Thus,展开更多
文摘Arsenic and fluoride are elements known to cause human health problems and it has been documented that both elements are found in high concentrations in the Guadiana Valley aquifer, in the state of Durango, Mexico. Since underground water is the source for potable water bottling companies commercialized in Durango City;such high concentrations reduced the quality of bottled water for human consumption according to NOM-041-SSA1-1993. Legislation establishes a maximum permissible limit (MPL) of 0.7 mg/L for fluoride and 0.025 mg/L for arsenic. In this research the main objective was to evaluate the quality of bottled water expended in Durango City with respect to the well from which water is extracted. Findings showed that the highest fluoride concentration was 5.86 mg/L (8.4 times MPL), with 100% of sampled brands exceeding the MPL (range: 1.09 to 5.86 mg/L). On the other hand, for arsenic, the highest concentration was 0.076 mg/L (threefold), with 38% exceeding the MPL (range: 0.001 to 0.076 ppm). Statistical analysis showed significant differences only for fluoride, according to Fisher LSD (Least Significant Difference) test, with an F value of 14.5 at a p value of 0.0005. According to the comparison between the quantified concentrations in bottled water and groundwater, it was found that groundwater was subjected to treatment;however, although a significant decrease in fluoride and arsenic concentration was observed, the removal processes used were not efficient to meet set standards.
文摘In this study</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> nineteen different brands of bottled mineral waters (7 brands local and 12 brands imported) were collected from supermarkets and independent food stores throughout Djibouti. The chemical composition mentioned on the labels of the nineteen bottled mineral waters ha</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> made the subject of a first verification by Ionic Balance Error (IBE). It was found out of the nineteen brands selected, 12 brands (2 brands local and 10 brands imported) had acceptable charge balance error. Correlation Analysis (CA), Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were used to analyze the data collected from the labels of bottled water. The obtained results showed that the 12 brands of studied waters can be grouped in 4 distinct classes with similar chemical characteristics. Two local and one imported brands have the same chemical composition but marketed under different names. It was observed that the chemical content local water brands w</span><span style="font-family:Verdana;">ere</span><span style="font-family:""><span style="font-family:Verdana;"> within the normal range prescribed by both WHO and USEPA except five imported water brands that have concentration values Ca, HCO</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">, Mg and SO</span><sub><span style="font-size:12px;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> beyond acceptable standards. Total hardness values classified most of the studied brands from moderate to very hard water.
文摘Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the addition of radiogenic 87Sr produced by the beta decay of 87Rb with a half-life of 4.88 ± 0.05 Ga.Thus,
