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大气光化学烟雾反应机理比较(Ⅰ)O3和NOx的比较 总被引:8,自引:0,他引:8
在相同初始和排放条件下,对四种应用较广的光化学烟雾反应机理(CB4-99,RADM2,RACM,SAPRC99)进行了比较.研究发现对于O3,在低VOCs/NOx时,四种机理模拟结果相关较小,平均相对标准偏差为7%,在高VOCs/NOx时,平均相对标准偏差为26%,差距较大;对于NOx,多数情况下RACM和RADM2的模拟结果较高,CB4-99和SAPRC99的模拟值偏低,其原因主要来源于不同机理中O3的生成对NOx及VOCs的敏感性不同而造成的.在用模式模拟O3和NOx时,应特别注意机理不同而带来的模拟结果差异. 相似文献
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Ning Zhang Hong Li You Zhou Wei Hu Zhixiang Zhang 《Environmental monitoring and assessment》2014,186(3):1377-1384
Two independent field trials were performed in Guangdong and Hubei, China in 2011 to investigate the dissipation and residue levels of triforine in strawberry and soil. A fast and simple method using gas chromatography with electron capture detector was developed and validated to determine triforine levels in strawberry and soil. The average recovery of triforine in strawberry ranged from 87.46 to 104.32 % with a relative standard deviation (RSD) of 0.72 to 4.54 %; that in soil ranged from 83.82 to 103.01 % with an RSD of 3.89 to 4.36 %. The limit of quantification of the proposed method was 0.01 mg/kg for both strawberry and soil. The results suggest that the triforine dissipation curves followed the first-order kinetic. The half-lives of triforine in strawberry from Guangdong and Hubei were 3.58 and 4.42 days, respectively; those in soil were 3.53 and 4.10 days, respectively. The terminal residues of triforine in strawberry ranged from 0.032 to 0.264 mg/kg at preharvest intervals of 0.5, 1, and 3 days. These values are lower than the maximum residue limit of 1 mg/kg in strawberry set by the Codex Alimentarius Commission. 相似文献
858.
State of rare earth elements in different environmental components in mining areas of China 总被引:3,自引:0,他引:3
China has relatively abundant rare earth elements (REEs) reserves and will continue to be one of the major producers of REEs for the world market in the foreseeable future. However, due to the large scale of mining and refining activities, large amounts of REEs have been released to the surrounding environment and caused harmful effects on local residents. This paper summarizes the data about the contents and translocation of REEs in soils, waters, atmosphere, and plants in REE mining areas of China and discusses the characteristics of their forms, distribution, fractionation, and influencing factors. Obviously high concentrations of REEs with active and bioavailable forms are observed in all environmental media. The mobility and bioavailability of REEs are enhanced. The distribution patterns of REEs in soils and water bodies are all in line with their parent rocks. Significant fractionation phenomenon among individual members of REEs was found in soil–plant systems. However, limited knowledge was available for REEs in atmosphere. More studies focusing on the behavior of REEs in ambient air of REE mining areas in China are highly suggested. In addition, systematic study on the translocation and circulation of REEs in various media in REEs mining areas and their health risk assessment should be carried out. Standard analytical methods of REEs in environments need to be established, and more specific guideline values of REEs in foods should also be developed. 相似文献
859.
Effect of heavy metals (Cu, Pb, and As) on the ultrastructure of Sargassum pallidum in Daya Bay, China 总被引:1,自引:0,他引:1
Concentrations of Cu, Pb, and As were determined in seawater, surface sediment, Sargassum pallidum collected from the Daya Bay, China. The influence of metal contamination on the marine alga was investigated at chemical and ultrastructural level. Mean concentrations of Cu (19.44 mg kg?1) and Pb (33.99 mg kg?1) were found to be high in sediment, whereas concentration of As (122.29 mg kg?1) in S. pallidum was higher than that in water and sediment. The ultrastructure of S. pallidum cells was anomalous and aberrant. Energy-dispersive x-ray spectroscopic analysis revealed that the nanometal particles in the form of comparatively high-electron density substance diffused in the cell structures constituted by Cu, Pb, As, etc. There is a remarkable similarity or correspondence in the anomalous elements between the geochemistry and the botanic cell, and the heavy metals have potential hazardous effect on the ocean ecology system in Daya Bay. 相似文献
860.
Li Zhang Dawen Zhang Yihua Wei Linguan Luo Tingcan Dai 《Environmental monitoring and assessment》2014,186(4):2185-2194
The levels of trace elements (As, Cd, Cr, Cu, Fe, Ni, Pb, Se, and Zn) in eight species of cultured freshwater fishes from Jiangxi province were determined by inductively coupled plasma-mass spectroscopy. All the studied trace element levels in fish muscles from Jiangxi province did not exceed Chinese national standard and European Union standard, and they were often lower than previous studies. The calculated target hazard quotient values for all the studied trace elements in fish samples were much less than 1, suggesting that the studied trace elements in fish muscles from Jiangxi province had not pose obvious health hazards to consumers. As and Cd concentrations in northern snakehead were much higher than that in other fishes, demonstrating that this fish species could be valuable as a bioindicator of As and Cd in environmental surveys. In addition, the highest concentrations of Fe, Zn, and moderate contents of other essential trace elements in crucian carp indicated that crucian carp could be a good nutrient source of essential trace elements for human health. 相似文献