Biokinetic modeling of heavy metals in earthworms

Studies concerning bioaccumulation kinetics and bioconcentration factor (BCF) of heavy metals like zinc (Zn), lead (Pb), chromium (Cr), cadmium (Cd), and copper (Cu) in earthworm Eudrilus eugeniae tissues including integument, gizzard, clitellum, and head region were undertaken. Calculated BCF, predicted K _ow, and predicted K _oc showed a significant correlation between heavy metals in different earthworm tissues, in substrate spiked with heavy metals. The regression coefficient (r ²) between heavy metal uptake concentration and exposure time varied between 0.73 and 0.99, indicating significant correlation. The K _oc was a maximum of 13.9016 in case of Cu and integument at an exposure time of 100 days and a minimum of 0.1114 in case of Cr with respect to head at the same exposure time. Earthworms accumulated heavy metals following chronic exposure to municipal solid waste containing heavy metals. BCF and uptake rate kinetics of heavy metals were calculated and showed increased values in head tissue followed by integument.     

水力负荷对生物陶粒反应器运行的影响

不力负荷较低是影响生物陶粒反应器在实际中运用推广的重要因素之一。本实验研究了不同水力负荷条件下生物陶粒反应器对进水中有机物,氨氮及其它污染物的去除效果。结果表明,不同水力负荷对生物陶粒反应器处理效果没有影响,对ＯＣ,氨氮,ＵＶ２５４,色度和浊度去除率分别为２０％,９０％,３０％,３８％,７６％。     

火灾中人群疏散延迟时间的研究

火灾中人员的疏散时间主要包括疏散前的延迟时间和在通道上的疏散时间。对疏散延迟时间的分布及其对疏散时间的影响进行了研究,利用Building Exodus软件对实际工程进行了模拟,并得出了一些重要的结论。这些结论对于修正传统疏散时间的工程计算方法、制定合理的人群管理对策具有重要的指导作用。     

跨漂时间对空气自动监测站二氧化硫准确度的影响

利用国家环保部标准样品研究所已知标准气体,选取绵阳市的三个城市空气自动监测站进行二氧化硫实验分析。结果表明,EC9850B二氧化硫监测仪跨漂后仪器响应快速升至最高值然后逐渐升高趋向稳定,通过连续跨漂的监测数据与已知标准气体的符合性确定仪器跨漂35min后基本稳定,并在标准气体中值附近波动,据此开始记录数据,准确度高,数据有效且质量可控。     

利用H+浓度变化控制含Cl-的氨氮废水的电解时间

采用电化学间接氧化法处理含Cl^-的中高浓度氨氮废水,针对不同浓度的氨氮废水的电解时间的控制,提出利用废水的H⁺浓度变化控制氨氮废水实际处理时间.从理论计算及对模拟和实际氨氮废水进行电解分析发现：当废水氨氮还没有完全降解时,每一个NH₄⁺降解的过程中会生成一个H⁺,c（H⁺）随着时间线性上升;当氨氮刚好完全降解时,c（H⁺）达到最大值;此后继续电解且废水pH＜7时,电解过程形成的OH^-会持续消耗H⁺,c（H⁺）随着时间线性下降.利用pH计实时监测废水的pH值,通过程控信号转换器进行c（H⁺）与pH值的换算,将pH值信号转化为c（H⁺）信号,可提高决策的准确性和灵敏度.     

陕西省地质灾害简编年表（1950—1992年）

本文扼要记述了陕西1950～1992年重大地质(崩塌、滑坡、泥石流)灾害及发生年代、地点、灾情,为本区国土整治、区域开发提供了基础资料。     

PROBLEMS IN FORECASTING WATER REQUIREMENTS1

ABSTRACT. Methodological problems associated with forecasting water requirements by use of regression analysis are examined. Problems occurring when long-range forecasts are based on linear and nonlinear extrapolation of time series models include possible changes in socioeconomic conditions, water allocation system structure, and limits to growth. Problems arising in forecasting based on multiple regression models are likely to involve serially dependent errors, multicollinear explanatory variables, and difficulties inherent to the presence of explanatory variables that must themselves be predicted.     

MODIFIED WATER QUANTITY RECEIVING MODEL FOR FLORIDA CONSERVATION AREAS1

ABSTRACT: The Conservation Areas in South Florida have been considered as one of the major water storage areas to provide a water supply for the Everglades National Park and Lower East Coast (LEC). Due to the increasing water demands of the area, additional backpumping of the surplus runoff from the LEC area into the Conservation Areas has been considered as one of several alternative plans. The Receiving Water Quantity (EPA, 1971) model has been adapted and modified to be applicable in the Conservation Areas to investigate the possible impact of additional inflow under various backpumping cases. The modification of the model included Manning's roughness coefficient, depth of flow, width of hypothetical channels through marsh areas, rainfall input, seepage rate, etc. The use of the Monte Carlo technique for area computations was found to be easy and time saving both in area and weighting rainfall input to each node. Comparison of results generated by this modified model with the recorded values in Conservation Areas 1 and 2A indicated that the model not only can be a very good evaluation tool to simulate the hydraulic regime of the Conservation Areas system but also a proper tool for investigating the impact of additional inflow resulting from the backpumping related to the water use planning and management.     

CASING AND LEAK DEPTHS,AND SOLUTE TRAVEL TIMES TO WELLS1

ABSTRACT: A mathematical solution based on porous media flow is developed for solute travel time to a well as affected by a leak around the upper part of the casing. Consider a well of radius 0.2 meters (m) penetrating, fully, a semiconfined aquifer of thickness 6 m with impermeable casing length of 4.5 m, and screened casing length 1.5 m. Around the upper 1.5 m of the impermeable casing length, there is a highly permeable region (a leak). The radius of influence of the well is 10 m. The porous flow medium has a hydraulic conductivity of 10 m/day and a porosity of 0.25. Between the water table and the water level in the well, there is a steady state pumped down head difference of 0.3 m. Solute travel time from a point at the bottom of the leak to the well is 2.33 days. If the leak is sealed (grouted), the travel time is 6.24 days. Examples of six different geometries are given. Laboratory studies verify the theory. The computations should be useful in the design and protection of water wells from solutes, such as from agriculture, industry, strip mines, or sanitary landfills.     

INTERACTIVE COMPUTER-AIDED HYDRAULIC DESIGN: CULVERTS1

ABSTRACT: Regular use of interactive computer programs in hydraulic design can materially increase the productivity of designers without sacrificing accuracy. This article considers the hydraulic design of culverts by interactive use of a computer program; this approach most profitably combines the speed and accuracy of the computer with the experience of the designer.