VERIFICATION OF THE RHEA-OROGRAPHIC-PRECIPITATION MODEL1

ABSTRACT: Observed April 1 snowpack accumulations within and near the Gunnison River basin in southwestern Colorado are compared with simulations from the Rhea-orographic-precipitation model to determine if the model simulates reliable magnitudes and temporal and spatial variability in winter precipitation for the basin. Twenty simulations of the Rhea model were performed using‘optimal’parameter sets determined for 10-kilometer (km) grids (10-km by 10-km grid cells) through stochastic calibration. Comparisons of Rhea-model simulations of winter precipitation with April 1 snowpack accumulations at 32 snowcourse stations were performed for the years 1972–1990. For most stations and most years the Rhea model reliably simulates the temporal and spatial variability in April 1 snowpack accumulations. However, in general, the Rhea-model underestimates April 1 snowpack accumulations in the Gunnison River basin area, and the underestimation is greatest for locations that receive the largest amount of snow. A significant portion of the error in Rhea-model simulations is due to the calibration of the Rhea model using gauge-catch precipitation measurements which can be as much as 50 percent below actual snowfall accumulations. Additional error in the Rhea-model simulations is a result of the comparison of gridded precipitation values to observed values measured at points.     

Laboratory scale studies on removal of chromium from industrial wastes

Chromium being one of the major toxic pollutants is discharged from electroplating and chrome tanning processes and is also found in the effluents of dyes,paint pigments,manufacturing units etc.Chromium exists in aqueous systems in both trivalent(Cr^3 )and hexavalent (Cr^6 )forms.The hexavalent form is carcinogenic and toxic to aquatic life,whereas Cr^3 is however comparatively less toxic.This study was undertaken to investigate the total chromium removal from industial effluents by chemical means in order to achieve the Pakistan NEQS level of 1 mg/L by the methods of reduction and precipitation.The study was conducted in four phase Ⅰ,the optimum pH and cost effective reducing agent among the four popular commercial chemicals was selected.As a result,pH of 2 was found to be most suitable and sodium meta bisulfate was found to be the most cost effective reducing agent respectively.Phase Ⅱ showed that lower dose of sodium meta hisulfate was sufficient to obtain 100% efficiency in reducing Cr^6 to Cr^3 ,and it was noted that reaction time had no significance in the whole process.A design curve for reduction process was established which can act as a tool for treatment of industrial effluents.Phase Ⅲ studies indicated the best pH was 8.5 for precipitation of Cr^3 to chromium hydroxide by using lime.An efficiency of 100% was achievable and a settling time of 30 minutes produced clear effluent.Finally in Phase Ⅳ actual waste samples from chrome tanning and electroplating industries,when precipitated at pH of 12 gave 100% efficiency at a settling time of 30 minutes and confirmed that chemical means of reduction and precipitation is a feasible and viable solution for treating chromium wastes from industries.     

珠江三角洲降水化学成分的区域特征研究

通过对珠江三角洲地区降水（降雨）化学成分的分析表明，该区可能存在二条降水物质通道，一条是从陆到海通道，从肇庆和广州分别至佛山、顺德、江门、台山、中山，至珠海出海，基本与西江和江河谷走向一致，另一条是从海到陆通道，从深圳始，到东莞和惠州，珠江口水面成为此二条通道的天然分隔屏障。地面源污染是造成该区局部降水酸度差异的调节因素，而造成全区降水酸化的根本原因是存在于平流层的区域性酸化大气层。南海海洋对降水     

离心脉冲静电除尘模型的除尘性能实验研究

介绍了一种直筒式离心脉冲静电除尘器，研究了其除尘效率与入口风速，直流基础电压，入口粉尘浓度等操作因素的关系；测定了在不同入口风速，不同供电情况下除尘器的分级效率，结果表明，离心脉冲静电除尘器具有结构简单，阻力损失低，除尘效率高等优点；脉冲供电能显著提高除尘器的分级效率。对粒径小于2μm的粉尘的捕集，入口风速为6.97m/s至12.79m/s时，脉并非中供电与直流供电相比，其分级效率提高10%-23%；与旋风相比，其分级效率提高37%-66%。     

重金属捕集剂处理含铅废水的试验研究

研究了重金属捕集剂的实验室合成及捕集重金属的机理,讨论了pH值、捕集剂加入量、反应时间、多种重金属离子共存对处理效果的影响,并就捕集产物的稳定性与传统中和沉淀法进行比较。试验结果表明:重金属捕集剂对Pb2+的去除率可达99%以上,处理后的废水达到《污水综合排放标准(》GB8978-1996)对铅的限定值,且处理效果不受pH值、共存重金属离子的影响。捕集剂与Pb2+生成螯合物的稳定性远高于中和沉淀法所得产物的稳定性,因而减少了捕集产物再次污染环境的风险。     

Influence of hydrogeochemical processes on zero-valent iron reactive barrier performance: a field investigation

Geochemical and mineralogical changes were evaluated at a field Fe0-PRB at the Oak Ridge Y-12 site concerning operation performance during the treatment of U in high NO3- groundwater. In the 5-year study period, the Fe0 remained reactive as shown in pore-water monitoring data, where increases in pH and the removal of certain ionic species persisted. However, coring revealed varying degrees of cementation. After 3.8-year treatment, porosity reduction of up to 41.7% was obtained from mineralogical analysis on core samples collected at the upgradient gravel-Fe0 interface. Elsewhere, Fe0 filings were loose with some cementation. Fe0 corrosion and pore volume reduction at this site are more severe due to the presence of NO3- at a high level. Tracer tests indicate that hydraulic performance deteriorated: the flow distribution was heterogeneous and under the influence of interfacial cementation a large portion of water was diverted around the Fe0 and transported outside the PRB. Based on the equilibrium reductions of NO3- and SO4(2-) by Fe0 and mineral precipitation, geochemical modeling predicted a maximum of 49% porosity loss for 5 years of operation. Additionally, modeling showed a spatial distribution of mineral precipitate volumes, with the maximum advancing from the interface toward downgradient with time. This study suggests that water quality monitoring, coupled with hydraulic monitoring and geochemical modeling, can provide a low-cost method for assessing PRB performance.     

废水除磷技术的研究与发展

目前 ,人们越来越重视污水除磷技术。本文介绍与评述了化学和生物两种除磷方式及其除磷机理和工艺 ,并着重介绍了生物除磷的现状、发展和研究动向     

Effects of uncontrolled particulate matter release on precipitation under warfare conditions

This study has shown theoretical, observed and experimental evidence of pollutants released, transported and deposited during the Kosovo conflict in 1999 and their effects on precipitation in Serbia. The greatest bombardment of the chemical industry, oil refineries and fuel storage in Serbia which occurred during April, resulted in releases of many hazardous, toxic and cancerogenic substances. The number of April's days with precipitation greater or equal to 0.1 mm in 1999 are compared to those in the period from 1961 to 1990 registered at thirty meteorological stations in Serbia and especially at the Belgrade-Observatory station in the period from 1888 to 1995. The maximums of days with precipitation greater or equal to 0.1 mm were at the wider Belgrade area and at the central and southwestern parts of Serbia during April 1999. This is confirmed by using the Eta trajectory analysis.     

脉冲供电在锌沸腾炉电除尘器上的应用

介绍了一种电除尘器脉冲供电的基本原理及其在锌沸腾炉电除尘器上的应用试验情况。结果表明，在基本保持同一工况条件下，脉冲供电比直流供电降低出口烟气含尘浓度50.4%～79.6%；脉冲供电能改善电除尘器运行性能，提高电除尘器改善系数达1.32；脉冲供电运行安全可靠。     

磷酸铵镁沉淀法脱氨机理、应用及沉淀剂循环

铵根离子可以和镁盐、磷酸根在适当的条件下生成磷酸铵镁沉淀,利用这一反应可以去除水中的氨氮.本文从磷酸铵镁的性质、反应机理、反应条件及沉淀剂循环利用等方面,对这一方法进行了介绍和总结,并对今后该技术发展提出了建议.