10. Identify the following conditions as being related to aerobic or anaerobic systems.a. Supports denitrification __________b. Contains O2 __________c. Following reaction occurs: SO42-  HS­­­- __________d. Saturated soils that limit exchange of air from atmosphere __________e. Following reaction occurs: Cr+3  CrO42- __________The Nitrogen CycleDr. Casey Name: ______________________Exam 3Spring 2003 Signature: ______________________Chem. 104Honor Statement: By signing this exam, you indicate that you have neither given nor received aid from any unauthorized source.Answer each question in the space provided. If you need more space, use the back of the sheet. All work must be shown to receive partial credit. You have until the regularly scheduled end of class to complete the exam. Good luck!1. Identify or draw the following features on the diagram below:aerated (unsaturated) zone confining layerconfined aquifer unconfined aquiferarrow indicating recharge arrow indicating site and direction of dischargeImpermeable RockStreamLand SurfaceWater Table2. If clean water were always available and inexpensive, we would not be as concerned as we are about water quality. Discuss the strategies that are used to obtain clean water in major metropolitan areas such as Los Angeles and New York City. Which of these strategies are usually not employed? Why?The strategies that we discussed in class are:a. Clean currently available water to meet desired usesb. Move clean water from another areac. Use less water3. There are several consequences of the overuse of groundwater.a. Define what overuse of groundwater is.b. Explain in detail how overuse of groundwater relates to 2 of the 3 situations below. i. Drinking water availabilityii. Subsidence of the groundiii. Saltwater intrusion4. Water has several important properties that are relatively unusual for its small size. Explain the following circumstances based on the water property given.a. Water is an unusually good solvent. What are the implications for surface and groundwater contamination?b. Solid water (ice) floats on top of liquid water. How does this affect the survival of aquatic species in cold climates?5. Drinking water wells often withdraw water from confined aquifers. Irrigation wells often withdraw water from either unconfined or confined aquifers. Explain why this is reasonable in terms of potential for aquifer contamination and desired uses for different water resources.6. A nitrogen fertilizer in the form of NH3 is applied to an aerobic soil with crops. What other forms of nitrogen could occur in the soil as a result of chemical transformations? Which forms do you expect to be major components, and which will be present in only small levels?7. Match the form of N with its given properties. More than one form of N may fit a given property.N2 N2O NO2-NO3- NH3NH4+Organic Na. N combined with carbon and hydrogen in biological molecules __________________b. N with an oxidation state of –3 __________________c. N that is toxic to fish __________________d. N in the form of a gas __________________e. N that is unavailable as a nutrient __________________7. Nitrogen fixation occurs through bacterial processes. Since the 1940’s, humans have also been capable of nitrogen fixation. What is nitrogen fixation? What are the implications of large-scale human nitrogen fixation on the global nitrogen problem?8. What is a riparian zone? What role do riparian zones play in the transformations of nitrogen? Specify the forms of N that are affected, the transformation processes involved and the conditions required for those transformations to occur.9. a. How do wetlands serve to keep phosphorus from contaminating lakes and rivers?b. Explain the difference in mechanisms by which wetlands retain N and P. Which nutrient can be removed permanently from contaminated water, N or P? Why?10. Identify the following conditions as being related to aerobic or anaerobic systems.a. Supports denitrification __________b. Contains O2__________c. Following reaction occurs: SO42-  HS- __________d. Saturated soils that limit exchange of air from atmosphere __________e. Following reaction occurs: Cr+3  CrO42-__________The Nitrogen CycleN2NH3Org NNO3-NO2-N2O