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951.
Jeffries D. S. Semkin R. G. Beall F. D. Franklyn J. 《Water, Air, & Soil Pollution: Focus》2002,2(1):5-22
The Turkey Lakes Watershed (TLW) was established in 1980 as asite for study of the ecosystem effects of acidic deposition, andsince then there has been 40% reduction in North AmericanSO2 emissions. Monitoring records for bulk deposition,shallow and deep ground water, two headwater streams and two lakeoutflows have been tested to identify statistically significantmonotonic trends. The TLW appears to be responding to decliningacidifying emissions because the most prevalent chemical trendacross sample types/stations was decreasing SO4
2-. Increasing pH was detected in four of the seven data sets, butonly the H+ decrease in bulk deposition was of a magnitudeto be an important ionic compensation for the SO4
2-decline. There is little evidence of acidification recovery inTLW waters however. Increasing alkalinity was found only in theoutflow of the penultimate lake of the basin, and in fact, deepground water and the other lake outflow had decreasing alkalinitytrends (i.e., continuing acidification). For the surface waterstations, the greater part of the ionic compensation fordeclining SO4
2- was decreasing base cations, and as aresult, these waters are probably becoming more dilute with time,although only the headwater streams exhibited decliningconductivity. Five of seven data sets had increasing dissolvedorganic carbon concentrations. Increasing NO3
- wasimportant in ground waters. Drought has strongly influencedtrends and delayed recovery by mobilizing S stored in catchmentwetlands and/or soils. 相似文献
952.
废旧车用载钯催化剂中钯的浸出研究 总被引:5,自引:0,他引:5
针对汽车尾气的污染,汽车排气系统都安装有含铂族金属的汽车催化剂.废旧汽车催化剂已成为铂族金属重要的二次资源.本文采用湿法浸出整体式蜂窝陶瓷汽车催化剂中的铂族金属钯.氧化焙烧废汽车催化剂除去积炭和其他有机物,再磨细过筛100目后烘干.预处理过的废催化剂用还原剂HCOOH溶液将催化剂中氧化态钯转化为单质钯,在70℃恒温下,用盐酸和氧化剂NaClO3选择性浸出钯.本文比较了几种浸出方法的结果,考察了HCl-NaClO3浸出体系的几个因素对钯浸出的影响,确定了最佳浸出条件.实验结果表明,HCl-NaClO3浸出体系在优化条件下能完全浸出催化剂中的钯,该方法可以用于钯的回收和对催化剂中的钯进行定量分析. 相似文献
953.
954.
Claude Amoros Jean -Claude Rostan Guy Pautou Jean -Paul Bravard 《Environmental management》1987,11(5):607-617
The wetland ecosystems occurring within alluvial floodplains change rapidly. Within the ecological successions, the life span of pioneer and transient stages may be measured in several years or decades depending on the respective influences of allogenic (water dynamics, erosion, and deposition) and autogenic developmental processes (population dynamics, eutrophication, and terrestrialization). This article emphasizes the mechanisms that are responsible for the ecosystem changes and their importance to environmental management. Two case studies exemplify reversible and irreversible successional processes in reference to different spatial and temporal scales. On the scale of the former channels, the standing-water ecosystems with low homeostasis may recover their previous status after human action on the allogenic processes. On the scale of a whole reach of the floodplain, erosion and deposition appear as reversible processes that regenerate the ecological successions. The concepts of stability and reversibility are discussed in relation to different spatiotemporal referential frameworks and different levels of integration. The reversible process concept is also considered with reference to the energy inputs into the involved subsystems. To estimate the probability of ecosystem regeneration or the cost of restoration, a concept of degrees of reversibility is proposed. 相似文献
955.
氯乙酸母液氢解制氯乙酸 总被引:2,自引:0,他引:2
以氯乙酸母液和氢气为原料,开发了氢解制氯乙酸的新工艺。文中介绍了氢解了反应原理和工艺流程,并介绍了母液预处理,催化剂筛选及氢解反应条件等试验。中试验连续运转的结果表明,工艺路线合理可行,催化剂活性稳定,单程氢解产品产率达到94%以上,产品氯乙酸的质量达到行业标准,装置运行安全可靠。 相似文献
956.
W. Keller N. D. Yan J. M. Gunn J. Heneberry 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):317-322
Over 7,000 lakes around Sudbury, Ontario, Canada were acidified by S deposition associated with emissions from the Sudbury
metal smelters and more distant S sources. Air pollution controls have led to widespread changes in damaged Sudbury lakes,
including increased pH and decreased concentrations of SO4, metals and base cations. While chemical improvements have often been substantial, many lakes are still acidified, although
water quality recovery is continuing. Biological recovery has been observed in some lakes among various groups of organisms
including fish, zooplankton, phytoplankton and zoobenthos. Generally, however, biological recovery is still at an early stage.
Lakes around Sudbury are also showing that the recovery of acid-damaged lakes is closely linked to the effects of other major
environmental stressors such as climate change, base cation depletion and UV-B irradiance. Future studies of the recovery
of acid-damaged lakes around Sudbury, and in other regions, will need to consider the interactions of these and other stressors. 相似文献
957.
958.
天然气中常含有硫化氢、一氧化碳和有机硫等酸性组分,酸性组分的存在会造成金属腐蚀、环境污染并进而危害人体健康等。文章简单介绍了天然气脱硫净化及硫磺回收工艺,重点对天然气生产过程中所产生的硫化氢、甲烷、硫磺、二氧化硫、一氧化碳、氮氧化物、噪声、高温等职业病危害因素进行了识别,分析并介绍了其影响及防护措施。 相似文献
959.
对国内外炼油废水深度处理与回用的现状作了比较,并针对炼油废水处理与回用技术进行了展望。 相似文献
960.