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921.
922.
923.
ABSTRACT: Maintenance of the more than 24 million septic tanks in the U.S. requires removal and disposal of septage. Disposal options include application to agricultural lands where the nutrients and organic matter can provide soil benefits. However, pathogens and contaminants are also contained in septage. An extensive search turned up very few data on septage quality, and those reveal high variability. The data used by the U.S. Environmental Protection Agency (EPA) in developing regulations had the lowest metal concentrations among the nine data sets that could be compared. Based on these data, EPA assumed that septage could be applied to agricultural land for more than 100 applications before reaching unacceptable cumulative loading of metals. They thus did not establish federal standards for metals in septage, and no monitoring is required under federal rules governing septage disposal. Analysis of the nine data sets we found showed that field site life would be reached in less than 100 applications for most septage and cumulative loading limits established by EPA for sewage sludges will be exceeded in 16 applications for some septage as opposed to the 100 application estimate used by EPA. Determination of acceptable cumulative loading depends on numerous technical and policy considerations. All septage sources reached the more restrictive loading limits such as those established by the New York State Department of Environmental Conservation (NYSDEC) and the recommendations in Cornell publications in less than 100 applications. In one case the cumulative limit for copper was exceeded in a single application. These findings suggest additional data are needed on septage quality and that the federal and state agencies responsible for regulating application of septage to agricultural land should reassess their standards. 相似文献
924.
水环境承载能力调控与水质信息系统模式的探讨 总被引:1,自引:0,他引:1
水环境承载能力是可持续发展理论的重要体现,它具有很强的动态、空间时空、水量水质兼顾、补偿等特性。建立水质信息系统基础平台,科学地利用和调控水环境承载能力,实现水环境保护目标的实现。本文就水环境承载能力调控与水质信息系统模式的建立进行了分析研究,并结合中国实情提出了建模总体框架。 相似文献
925.
不同有机负荷下氮缺乏对活性污泥膨胀的影响 总被引:4,自引:0,他引:4
有机负荷与营养物缺乏是活性污泥处理工艺中引起污泥膨胀的2个重要因素.本文研究了在低有机负荷条件下氮缺乏对活性污泥膨胀的影响.试验结果表明,营养物充足时,低有机负荷下并不一定发生污泥膨胀,并且反应过程中发生不完全的硝化反应.当进水中缺氮时,低有机负荷下,由于微生物对自身细胞物质的分解代谢作用,剩余污泥量减少,代谢产物中的营养物质在一定程度上缓解了进水中氮缺乏的影响,使得污泥沉降性能恶化程度并不严重.同时,还对污泥膨胀的控制与恢复进行了研究. 相似文献
926.
我国铁路笨零货物运输安全管理对策研究 总被引:2,自引:0,他引:2
铁路笨零货物运输安全问题一直是铁路运输企业在安全方面十分关心的问题之一。近几年出现的几次因笨零货物装载不当引起的铁路运输事故 ,使得笨零运输安全问题更加引人注意。笔者分析了我国铁路笨零货物运输中存在的问题 ,包括管理工作 ,偏载偏重问题 ,车辆技术状态 ,笨零货物的装载加固 ,职工激励机制 ,货运员素质等 5方面 ,主要从优化笨零货物作业环节 ,改进笨零货运组织方法 ,注重安全第一 ,完善激励机制 ,加强理论及硬件建设等 7个方面提出了对策。 相似文献
927.
Gareth K. Phoenix Jonathan R. Leake David J. Read J. Philip Grime John A. Lee 《Water, Air, & Soil Pollution: Focus》2004,4(6):159-167
Semi-natural calcareous and acidic grasslands are known to be sensitive to increased atmospheric N deposition. However, the fate of pollutant N within these systems is unknown. This paper reports on the first studies to determine the fate of added N within a calcareous and an acidic grassland subject to long-term simulated enhanced N deposition. Intact soil/turf cores were removed from field plots treated for six years with enhanced N deposition (ambient +0, +35 and +140 kg N ha–1 year–1). Cores were inserted into lysimeters and output fluxes of N were monitored in detail. Complete N budgets—calculated from the N flux data—showed considerable accumulation of N within the treated grasslands, up to 76% and 38% of pollutant N in the calcareous and acidic grasslands respectively. In the second study, the short-term (21 day) fate of pollutant N was determined by tracing 15N labelled ammonium nitrate (+35 kg N ha–1 year–1) though the acidic and calcareous lysimeters into plant, soil and leachate pools. Up to 91% and 59% of 15N was recovered in soils and vegetation of the calcareous and acidic grasslands respectively, with negligible amounts recovered in soil extractable ammonium and nitrate (<0.3%) and in leachate (<0.02%). This rapid short-term immobilisation of pollutant N supports the long-term accumulation of the element calculated from the N flux study. 相似文献
928.
D. W. Bacon O. T. Coomes A. A. Marsan N. Rowlands 《Journal of the American Water Resources Association》1986,22(1):29-38
ABSTRACT: A comparative study of the concentration of asbestos fibers in drinking water supplies of southeastern Quebec was undertaken to assess the relative contributions of fibers by asbestos-bearing railway ballast and naturally occurring asbestos deposits. Water samples were taken from areas where one or the other potential sources or neither potential source was present. In addition, rainwater samples were taken to assess the importance of atmospheric contributions. The sampling design accounted for potential variations in fiber counts due to the season, location and analytical procedures. Fiber concentrations were estimated from counts made on a JEOL 100CX scanning transmission electron microscope and statistically compared among areas. These levels were then compared with levels found in other areas of Canada and the United States. The results indicate that the rail ballast could be contributing statistically (albeit marginally) significant quantities of fibers to water supplies during the summer but not in the spring. Estimated concentrations in water supplies ranged between 1.7 × 106fibers/liter and 147.8 × 106fibers/liter. Fiber levels in samples taken during the spring were significantly higher and more variable than those taken during the summer. The presence of fibers in rainwater samples at concentrations of 1.9 × 106fibers/liter, 18.3 × 106fibers/liter and 23.7 × 106fibers/liter suggests that atmospheric transport may play an important role in contributing fibers to regional systems. Fiber levels found in these systems are not unique when compared to levels observed elsewhere in North America. 相似文献
929.
以南京化学工业(集团)公司为例,介绍在企业中实行排污许可证制度,可有效地控制污染物排放,并改变以往污染物排放的末端管理为生产全过程控制,强化了环保法制观念,协调了管理工作与监测工作之间的关系,使环保管理工作由被动变成主动。 相似文献
930.
沿海油田污染物入海通量及优化管理 总被引:3,自引:0,他引:3
胜利油田所在的黄河三角洲诸条河流按入海类型分为三种形式:设有防潮闸的感潮河;设有排涝站的入海河;直流入海的感潮河。按照各河流入海段面、流速、流量和水体污染物浓度,建立起各种感潮河污染物入海通量模式,计算结果说明沿海油田排放的石油类污染物入海通量为1456t/a,COD入海量为5720t/a。根据各条入海河流不同功能和污染物入海量,按照国家地表水质标准,制定出入海河流环境组合目标,用总量控制方法提出污染源削减要求,以保证黄河三角洲沿海滩涂环境质量。并以污染物入海通量、河流径流量、污染物自净系数和污染物削减量等因子建立各条河流优化管理模型,为保护环境提供对策。 相似文献