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991.
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993.
Influence of pyrene combination state in soils on its treatment efficiency by Fenton oxidation 总被引:1,自引:0,他引:1
Interactions of hydrophobic organic compounds (HOCs) with soil organic matter (SOM) determine their combination state in soils, and therefore strongly influence their mobility, bioavailability, and chemical reactivity. Contact time (aging) of an HOC in soil also strongly influences its combination state and environmental fate. We studied Fenton oxidation of pyrene in three different soils to reveal the influences of SOM, contact time, and combination state on the efficiency of vigorous chemical reactions. Pyrene degradation efficiency depended strongly on the dose of oxidant (H(2)O(2)) and catalyst (Fe(2+)); the greatest degradation was achieved at an oxidant to catalyst molar ratio of 10:1. Pyrene degradation differed among the three soils, ranging from 65.4% to 88.9%. Pyrene degradation efficiency decreased with increasing SOM content, and the aromatic carbon content in SOM was the key parameter. We hypothesize that pyrene molecules that combine with the compact net structure of aromatic SOM are less accessible to Fenton oxidation. Furthermore, pyrene degradation efficiency decreased considerably after aged for 30 days, but further aging to 60 and 180 days did not significantly change degradation efficiency. The Fenton oxidation efficiency of pyrene in both unaged and aged soils was greater than the corresponding desorption rate during the same period, perhaps because Fenton reaction can make pyrene more accessible to the oxidant through the enhancement of HOCs' desorption by generating reductant species or by destroying SOM through oxidation. 相似文献
994.
Effects of organic matter on phosphorus release kinetics in different trophic lake sediments and application of transition state theory 总被引:9,自引:0,他引:9
Sediments have a significant influence on the overlying water, and phosphorus (P) release from sediments is an important source for the lake eutrophication, particularly in shallow ones. In this study, effects of organic matter on P release from sediments in different trophic lakes from the middle and lower reaches of Yangtze River, China, were investigated, and the release kinetics of different P fractions at different temperature were studied. The results show that the release kinetics of soluble reactive phosphorus (SRP), dissolved organic phosphorus (DOP) and dissolved total phosphorus (DTP) were similar for the studied sediments, the release rate increased rapidly in the initial hours, and it increased gradually after 10h. The release kinetics of SRP, DOP and DTP followed the Power Function model. SRP was the major fraction among the released DTP, while DOP was an important fraction in the heavily polluted sediments. Organic matter restricted the SRP and DTP release while it promoted the DOP release. Both DOP and SRP release processes were endothermic. The thermodynamic properties in the P release kinetics were calculated and discussed. 相似文献
995.
996.
涂膜JT345耐候钢在青岛、沈阳、北京等地大气环境下曝晒2年,表现出良好的耐腐蚀性能,采用电子探针、X射线衍射等对大气挂片锈层形貌、结构、组成进行了分析,发现JT345耐候钢表面锈层主要由γ-FeOOH、α-FeOOH和Fe3O4组成.改性涂层处理可加速耐候钢表面生成致密保护性锈层,该锈层中富集大量的Cr、Cu、P等. 相似文献
997.
998.
加热炉通常采用原油或渣油为燃料,对炉管内流过的原油进行加热,以降低原油黏度,减少输送阻力.炉内盘管在高温及腐蚀性介质的作用下,常会发生腐蚀穿孔.对腐蚀发生的位置、原因进行了分析,并有针对性地提出了防护改进措施. 相似文献
999.
Multi-indicator assessment of water environment in government
environmental auditing 总被引:1,自引:0,他引:1
This study focused on a multi-indicator assessment methodology for governmental environmental auditing of water protection programs. The environmental status of Wuli Lake in China was assessed using the global indicators (driver-status-response) developed by the Commission on Sustainable Development, and four additional indicators proposed by the author: water quality, pollution load, aquatic ecosystem status, and lake sediment deposition. Various hydrological, chemical, biological and environmental parameters were used to estimate the values of the indicators for assessment of environmental status of the lake based on time series data sets for twenty years. The indicators proposed can be customized to meeting the needs for particular assessment of water protection programs. This method can be used to evaluate the performance of national environmental protection programs and provide technical support for environmental auditors. 相似文献
1000.