To evaluate lead and cadmium contamination in Moringa oleifera leaves powders marketed in Cotonou and health risks associated with its consumption, cross-sectional and analytical study were done from October 23th, 201...To evaluate lead and cadmium contamination in Moringa oleifera leaves powders marketed in Cotonou and health risks associated with its consumption, cross-sectional and analytical study were done from October 23th, 2012 to June 20th, 2013. Samples of Moringa powders were purchased at different outlets (health centers, supermarkets, pharmacy, etc.). Assays were performed by atomic absorption spectrophotometry after digestion according calcination method. Pb and Cd levels were compared with Codex Alimentarius standards, using the Student t test. Daily Exposure Doses (DDE) and Hazard Quotients (HQ) specific to each contaminant were calculated using a conventional method. Results revealed that the mean concentration of lead for all samples (1.526 mg/kg) exceeded of about 5.08 times the maximum allowable limit whereas cadmium levels (0.246 mg/kg) was not statistically higher than the standard. The highest concentrations of Pb and Cd are respectively 4.263 mg/kg and 0.354 mg/kg. Children are 2.3 to 3.8 times in greater danger than adults although all QD calculated are less than 1, reflecting that there is a low risk to consumers in general. For both metals, DJE specifically linked to the consumption of Moringa was less than 2% compared to other kinds of food intake. In conclusion, the current level of contamination (with lead and cadmium) of Moringa leaves powders marketed in Cotonou is not yet an alarming threat to consumers’ health. However, care must be taken to reduce chemical pollution especially soils where these plants grow.展开更多
The main objective of this paper is to assess the impact of various vehicular traffic densities on lead (Pb) accumulations in some environmental components in Katsina, a semi-arid urban area of Nigeria. Method...The main objective of this paper is to assess the impact of various vehicular traffic densities on lead (Pb) accumulations in some environmental components in Katsina, a semi-arid urban area of Nigeria. Methods This was achieved by collecting and analyzing samples of surface soils, fruits, kernels, leaves, and barks of Balenites aegyptica from locations of different vehicular traffic densities in the area, and analyzing them for lead, using atomic absorption spectrophotometry. Results The results obtained revealed that the Pb concentration in the high, medium, low, and zero traffic density areas are, 75, 53, 35, and 12 μg·g-1 respectively for the fruit pulp. They are also16, 13, 8, and 6 μg·g-1 for fruit kernel and 44, 28, 17, and 9μg·g-1 respectively for leaves. For tree barks, the values are 138, 97, 64, and 18 μg·g-1 respectively while for under-tree-canopy soil samples the mean values are 99, 74, 44, and 17 μg·g-1. In the case of outside-canopy soil samples, the mean values are 113, 91, 50, and 18 μg·g-1 respectively for the various classes of vehicular traffic density. Conclusion These results indicate a strong influence of vehicular traffic density on Pb emission into surrounding atmosphere and its subsequent precipitation on soil and components of B. aegyptica specie in the area. Of all the samples, tree bark should be the best index of assessing Pb pollution in the area, as it maintains the closest contact with the surrounding atmosphere. Since Pb has no known lower limit for human tolerance, there is an urgent need for Pb pollution control in the area to be effectively enforced.展开更多
危险电子废物阴极射线管(cathode ray tube,CRT)是当前我国电子垃圾处理处置中首要必须解决的难题,其关键在于含铅锥玻璃的处理处置。本研究探讨了真空碳热还原法从CRT锥玻璃中分离并回收有害重金属铅的同时回收钾和钠的规律。结果表明...危险电子废物阴极射线管(cathode ray tube,CRT)是当前我国电子垃圾处理处置中首要必须解决的难题,其关键在于含铅锥玻璃的处理处置。本研究探讨了真空碳热还原法从CRT锥玻璃中分离并回收有害重金属铅的同时回收钾和钠的规律。结果表明,铅、钾和钠的回收率随温度的升高、压力的降低、碳加入量的增加及保持时间的延长而增大;当温度为1000℃、系统压力为10 Pa时,加入10%的碳粉并保持4 h,铅回收率接近100%,钠和钾的回收率分别为65.04%和50.55%。该方法为废弃阴极射线管玻璃的无害化和资源化提供了理论依据和实验数据。展开更多
基金Foundation item:Project(2022YFC2904204)supported by the National Key R&D Program of ChinaProjects(52364048,52004115)supported by the National Natural Science Foundation of China+5 种基金Projects(202101BE070001-019,202101AT070116,202001AU070045)supported by the Yunnan Fundamental Research Projects,ChinaProject(2020)supported by the Yang Bin Scientist Studio of Yunnan Province,ChinaProject(2022)supported by the Yunnan Talents Support Project,ChinaProject(202302AB080002)supported by the Yunnan Key S&T Special Projects,ChinaProject(231100320300)supported by the Henan Key S&T Special Projects,ChinaProject(KKZ7201952006)supported by the High-level Talent Construction of Kunming University of Science and Technology,China。
文摘To evaluate lead and cadmium contamination in Moringa oleifera leaves powders marketed in Cotonou and health risks associated with its consumption, cross-sectional and analytical study were done from October 23th, 2012 to June 20th, 2013. Samples of Moringa powders were purchased at different outlets (health centers, supermarkets, pharmacy, etc.). Assays were performed by atomic absorption spectrophotometry after digestion according calcination method. Pb and Cd levels were compared with Codex Alimentarius standards, using the Student t test. Daily Exposure Doses (DDE) and Hazard Quotients (HQ) specific to each contaminant were calculated using a conventional method. Results revealed that the mean concentration of lead for all samples (1.526 mg/kg) exceeded of about 5.08 times the maximum allowable limit whereas cadmium levels (0.246 mg/kg) was not statistically higher than the standard. The highest concentrations of Pb and Cd are respectively 4.263 mg/kg and 0.354 mg/kg. Children are 2.3 to 3.8 times in greater danger than adults although all QD calculated are less than 1, reflecting that there is a low risk to consumers in general. For both metals, DJE specifically linked to the consumption of Moringa was less than 2% compared to other kinds of food intake. In conclusion, the current level of contamination (with lead and cadmium) of Moringa leaves powders marketed in Cotonou is not yet an alarming threat to consumers’ health. However, care must be taken to reduce chemical pollution especially soils where these plants grow.
文摘The main objective of this paper is to assess the impact of various vehicular traffic densities on lead (Pb) accumulations in some environmental components in Katsina, a semi-arid urban area of Nigeria. Methods This was achieved by collecting and analyzing samples of surface soils, fruits, kernels, leaves, and barks of Balenites aegyptica from locations of different vehicular traffic densities in the area, and analyzing them for lead, using atomic absorption spectrophotometry. Results The results obtained revealed that the Pb concentration in the high, medium, low, and zero traffic density areas are, 75, 53, 35, and 12 μg·g-1 respectively for the fruit pulp. They are also16, 13, 8, and 6 μg·g-1 for fruit kernel and 44, 28, 17, and 9μg·g-1 respectively for leaves. For tree barks, the values are 138, 97, 64, and 18 μg·g-1 respectively while for under-tree-canopy soil samples the mean values are 99, 74, 44, and 17 μg·g-1. In the case of outside-canopy soil samples, the mean values are 113, 91, 50, and 18 μg·g-1 respectively for the various classes of vehicular traffic density. Conclusion These results indicate a strong influence of vehicular traffic density on Pb emission into surrounding atmosphere and its subsequent precipitation on soil and components of B. aegyptica specie in the area. Of all the samples, tree bark should be the best index of assessing Pb pollution in the area, as it maintains the closest contact with the surrounding atmosphere. Since Pb has no known lower limit for human tolerance, there is an urgent need for Pb pollution control in the area to be effectively enforced.
文摘危险电子废物阴极射线管(cathode ray tube,CRT)是当前我国电子垃圾处理处置中首要必须解决的难题,其关键在于含铅锥玻璃的处理处置。本研究探讨了真空碳热还原法从CRT锥玻璃中分离并回收有害重金属铅的同时回收钾和钠的规律。结果表明,铅、钾和钠的回收率随温度的升高、压力的降低、碳加入量的增加及保持时间的延长而增大;当温度为1000℃、系统压力为10 Pa时,加入10%的碳粉并保持4 h,铅回收率接近100%,钠和钾的回收率分别为65.04%和50.55%。该方法为废弃阴极射线管玻璃的无害化和资源化提供了理论依据和实验数据。
