课程名称︰环境土壤物理学 课程性质︰探讨土壤的结构与质地如何跟空气与水作用 课程教师︰李达源 开课学院：农学院 开课系所︰农化系第一类群组必修 考试日期（年月日）︰Jun. 22, 2006 考试时限（分钟）：两节课，100钟 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1. Please define or explain the following terms in a few sentences. (15%) (a) Heat capacity (b) Richars'equation (c) Damping depth for thermal oscillations (d) Tortuosity factor for oxygen diffusion in soils (e) Retardation factor for a pesticide transport in soils 2. Draw a curve showing a typical relationship between hydraulic conductivity and soil water content and describe a laboratory experiment for measuring the hydraulic conductivity-water content functional relationship in unsaturated soil. Indicate what measurements must be taken and how the data is analyzed to produce K(θ). (10%) 3. A vertical soil column is in steady state evaporation. Three tensiometers read h z ──── ──── -15cm 10cm -40cm 20cm -100cm 30cm Calculate K (h) for two points in this system if the evaporation from the colum is 1cm/day (10%) 4. Oxygen is being consumed in a root zone at a rate R(z) = R0[1+(z/L)] for -L < z < 0. The units of R0 are mass of oxygen/volum soil/time. If the flux at z = -L is zero, calculate the steady state flux of oxygen for -L < z < 0. (10%) 5. What would the steady state volatilization flux be for a volatile organic chemical (VOC) through a soil cover assuming an industrial waste containing high concentrations of the VOC has been placed in a landfill and covered with 200cm thick of soil? Assume the soil had a constant and uniform water content (θ=0.1) and porosity (φ=0.4). The gaseous diffusion coefficient of this VOC in air is 4000cm^2/day and the saturated vapor density of the VOC is 0.3ng/cm^3. Assume the vapor density of the VOC in the soil surface was always maintained to be zero. (10%) 6. A max-min thermometer registers an annual temperature difference (Tmax - Tmin) if 10C at Z = -100cm in an area where the average max-min annual soil surface temperature difference Tmax-Tmin is 20C. Calculate:(10%) (a) soil damping depth (b) soil thermal diffusivity 7. You are asked to determine how deep to bury a water pipe in soil to prevent the pipe from freezing. Describe what measurements you would need to make, what information you need to obtain, and what calculations you would need to make. (10%) 8. Benzene which exists in gas form, dissolve in water, reacts in soil, and also adsorbs to soil solids. (10%) (a) In words write down the mass balance for this chemical for a unit volume located in soil. (b) If Henrys law is valid for this chemical, what simplifications may be made in the general solute flow equation rs + δ/δt[aCg +θCl +ρbCs] = δ/δZ[Dg^soil δCg/δZ ÷ δ/δZ[Dl^soil δCl/δZ - δ/δZ(JwCl) from the equation above? (c) If he linear, equilibrium adsorption is valid for describing the adsorption of this chemical by soil solids, what additional simplification may be made? (10%) 9. A trace organic chemical has a linear, equilibrium adsorption isotherm of Cs = 50μg/s soil for each CL = 1μg/mL solution (i.e. KD=50mL/g) for a saturated soil with bulk density ρb = 1.2g/cm^3 and saturated water content θs = 0.6. The soil has a saturated hydraulic conductivity Ks = 100cm/day in a column of L = 100cm height. Water is ponded continously to a height d = 20cm above the column. The bottom is open to the atmosphere. (15%) (a) Calculate the steady state water flux Jw and the average pore water velocity V. (b) If th ponded inlet solution is suddenly switched (at t = 0) to a solution containing chloride and the trace organic, calculate the chloride breakthrough time and the trace organic breakthrough time. (c) Draw breakthrough curves of chloride and the trace organic chemical and discuss how the diffusion-dispersion coefficient affects the shape of the breakthrough curves. --------------------------------试卷到此结束--------------------------------- --

※ 发信站: 批踢踢实业坊(ptt.cc) ◆ From: 140.112.249.137