APES Nitrogen Cycle Terms Flashcards

7383277386	Ammonia/Ammonium (NH3/NH4+)	Compounds of nitrogen and hydrogen that readily dissolve in water. In oxygen-rich water, NH4+ is microbially transformed to NO3- and in oxygen-poor water to molecular nitrogen. NH4+ and nitrate comprise most of the inorganic nitrogen in precipitation.	0
7383281540	Atmospheric Deposition	The process whereby airborne particles and gases are deposited on the earth's surface by wet deposition (precipitation) or by dry deposition (processes such as settling, impaction, and adsorption).	1
7383287072	Critical Load	The threshold of air pollution deposition that causes harm to sensitive resources in an ecosystem.	2
7383289440	Denitrification	The microbial process of converting NO3- through a series of intermediate steps to N2 gas, which occurs under very low oxygen conditions, such as in lake sediments.	3
7383291229	Dry Deposition	Atmospheric deposition that occurs when particles settle to a surface, collide with and attach to a surface, or when gases stick to a surface (adsorption) or are absorbed.	4
7383292879	Estuary	An arm of the sea at the mouth of a stream or river where freshwater and salt water meet.	5
7383295082	Eutrophication	A process in which nutrients degrade water quality due to excessive growth of microscopic plants and animals. As this matter dies and decays, it sometimes removes so much dissolved oxygen from the water that fish and other organisms cannot survive.	6
7383297669	Haber-Bosch process	Industrial process to convert inert, atmospheric N2 into NH3 using high pressures and temperatures and an iron catalyst.	7
7383300335	Hypoxia	A low-oxygen condition whereby decaying microscopic plants and animals in estuarine waters remove oxygen to a level below which most aquatic animals can survive. Although fish and shrimp can migrate from hypoxic zones, less mobile bottom dwellers cannot.	8
7383304341	Molecular nitrogen (N2)	An extremely stable gas, comprises 78% of the atmosphere. Converting this gas to other chemical compounds requires lots of energy. Also referred as Nonreactive Nitrogen (Nn-r).	9
7383307236	Nitrate (NO3-)	A compound of nitrogen and oxygen that is highly soluble in water. Nitrate is stable over a wide range of environmental conditions and is readily transported in surface water and groundwater.	10
7383310529	Non-reactive Nitrogen (Nn-r)	A nitrogen compound that is not ecologically or biologically active.	11
7383315130	Reactive Nitrogen (Nr)	Nitrogen compounds that are ecologically and biologically active. Nr can be in a reduced form as in ammonia (NH3), ammonium (NH4+), and organic compounds such as urea, amines, proteins, and nucleic acids. Nr can also be oxidized as in nitric acid (HNO3), nitrous acid (HONO), nitrous oxide (N2O), nitrogen dioxide (NO2), nitric oxide (NO2), and nitrate (NO3-).	12
7383343324	Total Deposition	The amount of a chemical compound that is deposited to earth's surface via wet and dry deposition processes.	13
7383485656	Watershed	A land surface from which water drains to a lake, stream, river, estuary, or bay.	14
7383495394	Wet Deposition	Atmospheric deposition that occurs when rain, snow, or fog carry gases, particles and dissolved materials to the earth's surface.	15