磁黄铁矿和石灰石改性硫磺发泡材料的脱氮除磷性能研究

基于硫磺自养反硝化(SAD)脱氮效率高、除磷效率低及磁黄铁矿自养反硝化(PAD)除磷效率高、脱氮效率低的特点,利用微细粒磁黄铁矿和石灰石与硫磺熔混、发泡得到磁黄铁矿与石灰石改性硫磺发泡材料(PLMSFM).通过批次试验探究磁黄铁矿和发泡剂配比对PLMSFM脱氮除磷的影响,优化得出硫磺∶石灰石∶磁黄铁矿∶碳酸氢钠的质量比...     

计算机硬盘驱动器的振动安全性分析

硬盘驱动器是计算机重要的外存储设备。它对随机振动环境较为敏感 ,是控制计算机系统工作安全性和进行信息处理的薄弱环节之一。笔者对计算机硬盘驱动器在随机振动环境下的工作安全性进行了分析 ,提出了导致硬盘工作失效的基本形式 ,针对读写过程中头盘振动响应位置偏移与读写模式间的关系给出了硬盘工作失效的判定方法。有关结果对计算机系统的振动安全分析和评估是有益的探讨。     

焦化厂A/O出水中的有机污染物分析

采用色谱－质谱（GC／MS）联用仪分析和鉴定了上海宝钢焦化厂A／O生化阶段出水的有机污染物组成,共检出各类有机污染物70多种。结合焦化废水专用混凝剂的混凝处理实验结果,指出了各类有机污染物的去除情况。     

USING CLIMATE FORECASTS FOR WATER MANAGEMENT: ARIZONA AND THE 1997–1998 EL NIÑO1

ABSTRACT: Unrelenting pressure on limited surface water supplies requires increasingly sophisticated water management approaches. Climate forecasts of seasonal precipitation and temperature are potentially useful, but the operational water management community currently underutilizes them. However, some agencies in Arizona took unprecedented advantage of forecasts for a potentially wet winter during the 1997–1998 El Niño event. This study investigates use of this information through a series of semi‐structured in‐depth interviews with key personnel from agencies responsible for emergency management and water supply; their jurisdictions ranged from urban to rural and local to regional. Interviews investigated information acquisition, interpretation, and incorporation into specific decisions and actions. While unprecedented actions were taken by some water management agencies and no agencies implemented inappropriate measures, some missed opportunities for more effective response, primarily through inaction. This study reveals a variety of technical factors and institutional characteristics affecting forecast use. Study findings emphasize the need for: (a) closer ongoing relationships between forecast producers and users, (b) increased institutional flexibility to exploit the increasing skill of seasonal climate forecasts, (c) demonstration projects of effective forecast use, and (d) a regional forum to facilitate information transfer between the hydro‐climatic research community and operational water managers.     

IMPACTS OF CLIMATE CHANGE ON MISSOURI RWER BASIN WATER YIELD1

ABSTRACT: Water from the Missouri River Basin is used for multiple purposes. The climatic change of doubling the atmospheric carbon dioxide may produce dramatic water yield changes across the basin. Estimated changes in basin water yield from doubled CO₂ climate were simulated using a Regional Climate Model (RegCM) and a physically based rainfall‐runoff model. RegCM output from a five‐year, equilibrium climate simulation at twice present CO₂ levels was compared to a similar present‐day climate run to extract monthly changes in meteorologic variables needed by the hydrologic model. These changes, simulated on a 50‐km grid, were matched at a commensurate scale to the 310 subbasin in the rainfall‐runoff model climate change impact analysis. The Soil and Water Assessment Tool (SWAT) rainfall‐runoff model was used in this study. The climate changes were applied to the 1965 to 1989 historic period. Overall water yield at the mouth of the Basin decreased by 10 to 20 percent during spring and summer months, but increased during fall and winter. Yields generally decreased in the southern portions of the basin but increased in the northern reaches. Northern subbasin yields increased up to 80 percent: equivalent to 1.3 cm of runoff on an annual basis.     

SAMPLING FRAME FOR IMPROVING PEBBLE COUNT ACCURACY IN COARSE GRAVEL‐BED STREAMS1

ABSTRACT: Improved sampling techniques are needed to increase the accuracy of pebble‐count particle‐size distributions used for stream studies in gravel‐bed streams. However, pebble counts are prone to operator errors introduced through subjective particle selection, serial correlation, and inaccurate particle‐size measurements. Errors in particle‐size measurements can be minimized by using a gravel template. Operator influence on particle selection can be minimized by using a sampling frame, 60 by 60 cm, in which sampling points are identified by the cross points of thin elastic bands. Serial correlation can be minimized by adjusting the spacing between the cross points and setting it equal to the dominant large particle size (=D₉₅). In a field test in a cobble‐bed stream, the sampling frame developed in this study produced slightly coarser size distributions, particularly in the cobble range, than the traditional heel‐to‐toe walk that selects particles with a blind touch at the tip of the boot. The sampling frame produced more similar sampling results between two operators than heel‐to‐toe walks. The difference between the two sampling methods is attributed to an unbiased selection of fine and coarse particles when using the sampling frame.     

Formation characteristics of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar PCBs in fly ash from a gasification–melting process of municipal solid waste

PCDDs/DF and Co-PCB (dioxin) formations were studied with ash from a newly developed gasification and melting process for municipal solid waste. Ash samples were heated in a laboratory-scale fixed-bed reactor. Emphasis was placed on the effects of the type and composition of ash, temperatures, gas residence time, and gaseous organic precursors. Investigations using macroscopic and homologue distribution analyses led to the following conclusion. The ash from the gasification–melting process had the ability to generate dioxins in flue gas. A possible carbon source is unburned carbon in the ash samples, although this was very low (less than 0.01%). An experimental result that the level of dioxins generated from preheated fly ash obtained from a conventional incinerator was much lower than that from nonheated fly ash supported this conclusion. Dioxin concentrations obviously showed temperature dependence and peaked at 350°C. Dioxins formed in a gasification–melting process ash were readily desorbed from the surface, probably because of the low carbon content of the ash. There was no experimental evidence that gaseous organic precursors fed to the reactor generated dioxins. Therefore, an organic precursor was not essential for the formation of dioxins. A good linear relationship obtained between PCDDs/DFs and gas residence time also supported the assumption. Received: February 14, 2000 / Accepted: June 30, 2000     

Is The Ca + K + Mg/Al Ratio in the Soil Solution a Predictive Tool for Estimating Forest Damage?

The ratio between (Ca +K +Mg) and Al in nutrientsolution has been suggested as a predictive tool forestimating tree growth disturbance. However, the ratiois unspecific in the sense that it is based on severalelements which are all essential for plant growth;each of these may be growth-limiting. Furthermore,aluminium retards growth at higher concentrations. Itis therefore difficult to give causal and objectivebiological explanations for possible growthdisturbances. The importance of the proportion ofbase-cations to N, at a fixed base-cation/Al ratio, isevaluated with regard to growth of Picea abies.The uptake of elements was found to be selective;nutrients were taken up while most Al remained insolution. Biomass partitioning to the roots increasedafter aluminium addition with low proportions of basecations to nitrogen. We conclude that the low growthrates depend on nutrient limitation in thesetreatments. Low growth rates in the high proportionexperiments may be explained by high internal Alconcentrations. The results strongly suggest thatgrowth rate is not correlated with the ratio in therooting medium and question the validity of usingratios as predictive tools for estimating forestdamage. We suggest that growth limitation of Picea abies in the field may depend on lowproportions of base cations to nitrate. It istherefore important to know the nutritional status ofthe plant material in relation to the growth potentialand environmental limitation to be able to predict andestimate forest damage.     

Adsorbable organic halides (AOX), AOX formation potential, and PCDDs/DFs in landfill leachate and their removal in water treatment processes

Adsorbable organic halides (AOX) and AOX formation potential (AOXFP) were investigated in 46 landfill lea-chates as potentially toxic parameters. AOX in landfill leachate was within the range <10–2200 μg Cl/l, and AOXFP was within 51–15 000 μg Cl/l. AOX and AOXFP correlated with chemical oxygen demand (COD). AOX discharge from closed landfills was generally lower than that from operating landfills. The molar ratio of AOXFP/total organic carbon (TOC) suggested that organic compounds in a leachate have a double bond every 15–190 carbons under the supposition that one chlorine would add to one double bond. The five landfills discharging high-level AOXFP (>4000 μg Cl/l) were all landfills where sludge had been dumped. The removal efficiencies of three parameters through leachate treatment processes were as follows: polychlorinated dibenzo-dioxins/dibenzo-furans (PCDDs/DFs) > TOC > AOX. PCDDs/DFs were substantially removed at p.p.t. levels, while AOX was hardly removed at relatively low levels. Received: February 14, 2000 / Accepted: January 9, 2001     

浅论ISO／DIS9001、ISO14001及OHSMS试行标准的关系

本文通过ISO／DIS9001、ISO14001和OHSMS试行标准的比较,为组织建立QMS、EMS和OHSMS提供帮助。