Heavy metal contamination of soil resulting from sewage irrigation is a cause of serious concern due to the potential health impacts of consuming contaminated products. In this study an assessment made of the impact o...Heavy metal contamination of soil resulting from sewage irrigation is a cause of serious concern due to the potential health impacts of consuming contaminated products. In this study an assessment made of the impact of sewage irrigation on heavy metal contamination of Spinach, Cabbage, Beetroot, Reddish, Okra, Tomato, and Cucumber is widely cultivated and consumed in urban India, particularly by the poor. A field study was conducted at seven major sites that were irrigated by either treated, (Dhandupura) or untreated wastewater in the suburban areas of Agra, India. Samples of irrigation water, soil, and the edible portion of all the vegetables were collected monthly during the winter seasons and were analyzed for Fe, Cd, Cu, Zn, and Pb. Heavy metals in irrigation water were below the internationally recom- mended (WHO) maximum permissible limits set for agricultural use for all heavy metals except Cd at all the sites. Similarly, the mean heavy metal concentrations in soil were below the Indian standards for all heavy metals, but the maximum value of Cd recorded during January was higher than the standard. However, in the edible portion of spinach, the Cd concentration was higher than the permissible limits of the Indian standard during summer, whereas Pb concentrations were higher in winter seasons. Results of correlation analysis were computed to assess the relationship between individual heavy metal concentration in the vegetable samples. The study concludes that the use of treated and untreated wastewater for irrigation has increased the contamination of Cd, Pb in edible portion of vegetables causing potential health risk in the long term from this practice. The study also points to the fact that adherence to standards for heavy metal contamination of soil and irrigation water does not ensure safe food. Fe was measured abundant in soil whereas Pb and Cd were found more in untreated sites as compared to treated site. Correlation, paired T-test and ANOVA were also carried out for pre post harvested soil and vegetables.展开更多
三角形电极离子阱(triangular-electrode linear ion trap,TeLIT)是一种新型结构的线性离子阱,具有简单的电极结构和良好的分析性能。为进一步提高TeLIT的离子探测效率,本实验将离子出射方向的2个电极设置为不同角度,建立非对称结构的Te...三角形电极离子阱(triangular-electrode linear ion trap,TeLIT)是一种新型结构的线性离子阱,具有简单的电极结构和良好的分析性能。为进一步提高TeLIT的离子探测效率,本实验将离子出射方向的2个电极设置为不同角度,建立非对称结构的TeLIT,通过引入非对称场实现离子单向出射。通过分析电极角度差与其内部电场分布的关系,并模拟离子运动轨迹,获得离子出射情况和模拟质谱峰。理论模拟结果显示:当离子出射方向三角电极的角度差Δα=15°时,在优化的AC频率条件下,三角形电极离子阱的m/z610离子单向出射率可达95%以上,且质量分辨率达到2 647。经优化几何参数后的非对称三角形电极离子阱可在几乎不损失分辨率的情况下实现离子单向出射,大幅提高了单检测器模式下TeLIT的离子探测效率和仪器的灵敏度,使其在小型化质谱仪的开发中具有显著优势。展开更多
文摘Heavy metal contamination of soil resulting from sewage irrigation is a cause of serious concern due to the potential health impacts of consuming contaminated products. In this study an assessment made of the impact of sewage irrigation on heavy metal contamination of Spinach, Cabbage, Beetroot, Reddish, Okra, Tomato, and Cucumber is widely cultivated and consumed in urban India, particularly by the poor. A field study was conducted at seven major sites that were irrigated by either treated, (Dhandupura) or untreated wastewater in the suburban areas of Agra, India. Samples of irrigation water, soil, and the edible portion of all the vegetables were collected monthly during the winter seasons and were analyzed for Fe, Cd, Cu, Zn, and Pb. Heavy metals in irrigation water were below the internationally recom- mended (WHO) maximum permissible limits set for agricultural use for all heavy metals except Cd at all the sites. Similarly, the mean heavy metal concentrations in soil were below the Indian standards for all heavy metals, but the maximum value of Cd recorded during January was higher than the standard. However, in the edible portion of spinach, the Cd concentration was higher than the permissible limits of the Indian standard during summer, whereas Pb concentrations were higher in winter seasons. Results of correlation analysis were computed to assess the relationship between individual heavy metal concentration in the vegetable samples. The study concludes that the use of treated and untreated wastewater for irrigation has increased the contamination of Cd, Pb in edible portion of vegetables causing potential health risk in the long term from this practice. The study also points to the fact that adherence to standards for heavy metal contamination of soil and irrigation water does not ensure safe food. Fe was measured abundant in soil whereas Pb and Cd were found more in untreated sites as compared to treated site. Correlation, paired T-test and ANOVA were also carried out for pre post harvested soil and vegetables.
文摘三角形电极离子阱(triangular-electrode linear ion trap,TeLIT)是一种新型结构的线性离子阱,具有简单的电极结构和良好的分析性能。为进一步提高TeLIT的离子探测效率,本实验将离子出射方向的2个电极设置为不同角度,建立非对称结构的TeLIT,通过引入非对称场实现离子单向出射。通过分析电极角度差与其内部电场分布的关系,并模拟离子运动轨迹,获得离子出射情况和模拟质谱峰。理论模拟结果显示:当离子出射方向三角电极的角度差Δα=15°时,在优化的AC频率条件下,三角形电极离子阱的m/z610离子单向出射率可达95%以上,且质量分辨率达到2 647。经优化几何参数后的非对称三角形电极离子阱可在几乎不损失分辨率的情况下实现离子单向出射,大幅提高了单检测器模式下TeLIT的离子探测效率和仪器的灵敏度,使其在小型化质谱仪的开发中具有显著优势。
