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991.
992.
DSD酸氧化缩合废水浓缩液回用试验研究 总被引:4,自引:1,他引:4
研究了DSD酸氧化缩合废水浓缩液回用到原生产过程的可行性。对DSD酸氧化缩合废水可采用萃取技术分离出其中97%的有机物,反萃产生的4-8倍的浓缩液返回到DSD酸生产中的氧化缩合单元后,可提高DNS酸的收率约7.43%,且不会明显影响产品的纯度,浓缩液8次循环磁用试验的结果表明,虽然DSD酸氧化缩合废水的COD从15000-20000mg/L提高到20000-29000mg/L,但没有显著持续增长的趋势,表明反应液中副产物的浓度得到了有效的控制。 相似文献
993.
994.
Trends in the Water Chemistry of High Altitude Lakes in Europe 总被引:2,自引:0,他引:2
Mosello R. Lami A. Marchetto A. Rogora M. Wathne B. Lien L. Catalan J. Camarero L. Ventura M. Psenner R. Koinig K. Thies H. Sommaruga-Wögrath S. Nickus U. Tait D. Thaler B. Barbieri A. Harriman R. 《Water, Air, & Soil Pollution: Focus》2002,2(2):75-89
Here we present the chemical trends of seven high altitude lakes, analysed within the AL:PE and MOLAR Projects of the EU (1999) and selected on the basis of the availability of complete and reliable data for the period 1984–1999. The lakes are representative of the Scandinavian Alps, the Cairngorm Mountains in Scotland, the Alps and the Pyrenees. Significant trends were identified for some indicators of acidification, for instance pH and alkalinity, but not all lakes reacted similarly to decreasing depositions of sulphate and base cations. Differences in lake response are discussed in relation to recent variations of atmospheric deposition chemistry and associated changes in climatic conditions. Beside individual variations of the studied lakes, depending, among other things, on altitude and morphology, catchment characteristics and climate trends play a major role for the reaction of high altitude lakes on changes in atmospheric depositions. 相似文献
995.
996.
997.
Anne Chin Daniel L. Harris Todd H. Trice Jeffrey L. Given 《Journal of the American Water Resources Association》2002,38(6):1521-1531
ABSTRACT: In Yegua Creek, a principal tributary of the Brazos River in Texas, surveys of a 19 km channel reach downstream of Somerville Dam show that channel capacity decreased by an average of 65 percent in a 34 year period following dam closure. The decrease corresponds with an approximately 85 percent reduction in annual flood peaks. Channel depth has changed the most, decreasing by an average of 61 percent. Channel width remained stable with an average decrease of only 9 percent, reflecting cohesive bank materials along with the growth of riparian vegetation resulting from increased low flows during dry summer months. Although large changes in stream channel geometry are not uncommon downstream of dams, such pronounced reductions in channel capacity could have long‐term implications for sediment delivery through the system. 相似文献
998.
Harold L. Stone 《Journal of the American Water Resources Association》2002,38(4):1019-1026
ABSTRACT: This study was designed to give insight into the values considered in environmental policy and illustrate the respondents' personal constructions related to creating policy through the development of a graphic tool. Using both qualitative and quantitative methods, this study anonymously captured the intensity of values currently held by decision makers and tracked changes in values over time. Data were acquired through observations of and interviews with stakeholders in a five‐year wetland mitigation bank permitting process at the Galveston District of the U.S. Army Corps of Engineers. The study included public and private sector respondents in both governmental and nongovernmental roles. The resulting representations of professional and personal stakeholders' values can be used as a tool for improving information exchange in policy negotiation and provides insight into the complexity of individual and corporate perceptions of a policy issue. 相似文献
999.
1000.
Rosanna L. Mattingly Edwin E. Herricks Douglas M. Johnston 《Environmental management》1993,17(6):781-795
The environmental impact of loss of natural stream and riparian habitat is of concern throughout the United States and Europe.
Environmental impacts related to such activities as channelization of and levee construction along streams and rivers are
particularly apparent in the Midwestern United States. The objective of the research presented here was to delineate the extent,
relative degree of impact, and implications for management of channelization and levee construction along watercourses located
in the state of Illinois. According to records maintained through the Illinois Streams Information System data base (Illinois
Department of Conservation), nearly 25% of surface water resources in the state have been modified directly by channelization
and/or levee construction. Reviews of agency records, elaboration of case histories, interviews with agency personnel, and
inspections of impacted sites indicated that these alterations have occurred without the benefit of effective mitigation.
Although permit records may provide suggestions for mitigation to be incorporated in the design of a particular project, permits
issued generally do not require even minimal instream habitat and bank stabilization efforts in conjunction with channel alteration.
Information derived from policy and case study analyses suggests that institutional constraints, rather than lack of particular
understanding about mitigation, provide major barriers to protecting the state's surface water resources in terms of regulatory
review, policy interpretation and implementation, and project evaluation. Recommendations for environmental management efforts
regarding these and similar channel alterations are elaborated from these findings. 相似文献