IFNz gas is so abundant in the Earth\'s atmosphere and in the oceans, how could
ID: 292631 • Letter: I
Question
IFNz gas is so abundant in the Earth's atmosphere and in the oceans, how could nitrogen ever limit productivity in the ocean? (2 points) 66. How can fertilizer runoff harm Chesapeake Bay? (2 points) Extra credit: a) Explain why Chesapeake Bay experiences seasonal hypoxia and anoxia (dead zones) in its water column. Make sure you discuss the role of primary production and w at limits it, respiration, and vertical mixing in the entire water b) Why is hypoxia a problem in the summer, but not during the winter? c) What human activities are column. affecting hypoxia (making it better or worse) in the Bay? (6 points)Explanation / Answer
65) Nitrogen is a primary nutrients required by the living organism for their survival. Although nitrogen is very abundant as N2 ,it is largely inaccessible in this form to most organism, making nitrogen a scare resources and often limiting primary productivity in many ecosystem. Most of the microrganisms are assumed to use inorganic N in the form of nitrate, nitrite and ammonia. Low concentration of these compounds cam limit the productivity rate in the surface layer of ocean.
66) Fertilizer runoff can extremely harm the Chesapeake bay. .It is said that about 30% of the bay's phosphorus load comes from the urban and suburban runoff.Excess nitrogen and phosphorus along with the sediments can cause poor water quality, which can increase the eutrophication ,which will eventually reduce the oxygen level and harm the habitat.Excess fertilizer runoff can seep directlyinto uderground water which can harm the Bay and local waterways.
a)- Chesapeake Bay experience seasonal hypoxia and anoxia in its water coloumn due to severe case of eutrophication.Eutrophication is a condition in the water body is caused due to over enrichment causing abundant growth of algae, phytoplanktons and macroscopic plants; deminishing the oxygen availabilty due accumalation and decompose the biomass of those organisms.Thus also limiting the rate of primary production or growth which will indeed not replenish enough oxygen . This condition largely affect the ecosystem of the Bay and can be severe in case the bay's the water coloumn is stratified .In the bottom of water decaying organisms accumulates which is below the density gradient , consuming the oxygen which is not regenerated by the mixing from the surface waters. Thus, the bay would experience hypoxia or even anoxia seasonal, which results in devoid of animal life.
b) -Natural stratification of the water occurs during summer, where warmer water floats on top of cooler saltier water that is more dense ,hence preventing the mixing of surface and bottom waters. This difference in density is called pycnocline. The surface layer of the water will be well oxygenated from the atmosphere and photosynthesis but making oxygen difficult to pass through the pycnocline into the bottom layer.Hence, decaying algae and other organic material and animal in the bottom will use up the oxygen faster than to replenish. Thus, hypoxia emerges and stay as long as stratification last.