Problem 3 [20 points!. In groundwater, the chlorinated solvent trichloroethylene
ID: 115565 • Letter: P
Question
Problem 3 [20 points!. In groundwater, the chlorinated solvent trichloroethylene (TCE) can biodegrade over time, resulting in a decrease in TCE. In a small aquifer in Minnesota, TCE was initially measured at a concentration of 1800 g/L but degraded over time in a first order process with a half-life of 1.3 years. Assume the aquifer was well mixed with constant volume and that transport and volatilization of TCE were negligible. a) Calculate the first-order degradation rate constant from the given half-life. b) Starting from rate of change of TCE concentration in the aquifer over time. the conservation of mass equation, provide an equation using only variables (symbols) for the lus to analytically integrate your equation for the rate of change of TCE. Show your work d) Starting with a blank spreadsheet, plot the result in Excel over a time period of 5 years. Set up your spreadsheet so there is a section at the top for constants (with units), and refer to those constants in your equations. Plot with a timestep of 0.2 yr. e) Explain how you will use the Euler method to numerically integrate the rate of change of TCE. Your tion should have two equations (with only variables) that show how you will calculate at each time step explana (7 the concentration and (i) the rate of change of concentration 1) In the same spreadsheet that you used in Part D, use Excel to implement your integration scheme. Use a timestep of 0.2 yT. Add your numerical solution to the SAME PLOT that has your analytical solution. Hint: che analytical and numerical solutions should match.). Tun in a printed copy of your plot,plus the FIRST FEW heet. (We need to see the first few rows of each column, plus your plot; try to fit that all on the same page to save paper.)Explanation / Answer
ANSWER:
Groundwater is the water present beneath Earth's surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from, and eventually flows to, the surface naturally; natural discharge often occurs at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.
Typically, groundwater is thought of as water flowing through shallow aquifers, but, in the technical sense, it can also contain soil moisture, permafrost (frozen soil), immobile water in very low permeability bedrock, and deep geothermal or oil formation water. Groundwater is hypothesized to provide lubrication that can possibly influence the movement of faults. It is likely that much of Earth's subsurface contains some water, which may be mixed with other fluids in some instances. Groundwater may not be confined only to Earth. The formation of some of the landforms observed on Mars may have been influenced by groundwater. There is also evidence that liquid water may also exist in the subsurface of Jupiter's moon Europa
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