Hypoxia - Revision history

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energy>Ethan.boechler at 20:37, 17 May 2021

2021-05-17T20:37:37Z

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	[[Category:~~Done 2017-07-01~~]]		[[Category:Chad edit]]
			[[Category: Translated to French]]
			[[fr:Hypoxie]]
	<onlyinclude>'''Hypoxia''' simply means low [[oxygen]]. This can apply to a lack of oxygen in [[air]], but in the context of [[hydropower]] hypoxia refers to low concentrations of dissolved oxygen in water. An extreme case of hypoxia is '''anoxia''', when there is no oxygen. When there is a low concentration of oxygen in [[water]] it is problematic for ecosystems that rely on this water. Water lacking in oxygen is known as hypoxic water.<ref>USGS. (August 21, 2015). ''Hypoxia Definition'' [Online]. Available: http://toxics.usgs.gov/definitions/hypoxia.html</ref> Generally, hypoxic waters have dissolved oxygen concentrations of less than 2 or 3 [[ppm]].</onlyinclude><ref name="RE1">US EPA. (August 20, 2015). ''Hypoxia 101'' [Online]. Available: http://water.epa.gov/type/watersheds/named/msbasin/hypoxia101.cfm</ref> When large stretches of open water become hypoxic they are unable to sustain life, and are thus known as dead zones.<ref name="RE2">NOAA. (August 20, 2015). ''Hypoxia'' [Online]. Available: http://oceanservice.noaa.gov/hazards/hypoxia/</ref> Even though fish live underwater, they still need oxygen to survive.		<onlyinclude>'''Hypoxia''' simply means low [[oxygen]]. This can apply to a lack of oxygen in [[air]], but in the context of [[hydropower]] hypoxia refers to low concentrations of dissolved oxygen in water. An extreme case of hypoxia is '''anoxia''', when there is no oxygen. When there is a low concentration of oxygen in [[water]] it is problematic for ecosystems that rely on this water. Water lacking in oxygen is known as hypoxic water.<ref>USGS. (August 21, 2015). ''Hypoxia Definition'' [Online]. Available: http://toxics.usgs.gov/definitions/hypoxia.html</ref> Generally, hypoxic waters have dissolved oxygen concentrations of less than 2 or 3 [[ppm]].</onlyinclude><ref name="RE1">US EPA. (August 20, 2015). ''Hypoxia 101'' [Online]. Available: http://water.epa.gov/type/watersheds/named/msbasin/hypoxia101.cfm</ref> When large stretches of open water become hypoxic they are unable to sustain life, and are thus known as dead zones.<ref name="RE2">NOAA. (August 20, 2015). ''Hypoxia'' [Online]. Available: http://oceanservice.noaa.gov/hazards/hypoxia/</ref> Even though fish live underwater, they still need oxygen to survive.

Jmdonev: 1 revision imported

2017-08-29T01:46:51Z

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Jmdonev at 17:09, 28 July 2017

2017-07-28T17:09:01Z

← Older revision		Revision as of 17:09, 28 July 2017
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	[[Category:Done ~~2015~~-09-05]]		[[Category:Done 2017-07-01]]
	<onlyinclude>'''Hypoxia''' simply means low [[oxygen]]. This can apply to a lack of oxygen in [[air]], but in the context of [[hydropower]] hypoxia refers to low concentrations of dissolved oxygen in water. An extreme case of hypoxia is '''anoxia''', when there is no oxygen. When there is a low concentration of oxygen in [[water]] it is problematic for ecosystems that rely on this water. Water lacking in oxygen is known as hypoxic water.<ref>USGS. (August 21, 2015). ''Hypoxia Definition'' [Online]. Available: http://toxics.usgs.gov/definitions/hypoxia.html</ref> Generally, hypoxic waters have dissolved oxygen concentrations of less than 2 or 3 [[ppm]].</onlyinclude><ref name="RE1">US EPA. (August 20, 2015). ''Hypoxia 101'' [Online]. Available: http://water.epa.gov/type/watersheds/named/msbasin/hypoxia101.cfm</ref> When large stretches of open water become hypoxic they are unable to sustain life, and are thus known as dead zones.<ref name="RE2">NOAA. (August 20, 2015). ''Hypoxia'' [Online]. Available: http://oceanservice.noaa.gov/hazards/hypoxia/</ref> Even though fish live underwater, they still need oxygen to survive.		<onlyinclude>'''Hypoxia''' simply means low [[oxygen]]. This can apply to a lack of oxygen in [[air]], but in the context of [[hydropower]] hypoxia refers to low concentrations of dissolved oxygen in water. An extreme case of hypoxia is '''anoxia''', when there is no oxygen. When there is a low concentration of oxygen in [[water]] it is problematic for ecosystems that rely on this water. Water lacking in oxygen is known as hypoxic water.<ref>USGS. (August 21, 2015). ''Hypoxia Definition'' [Online]. Available: http://toxics.usgs.gov/definitions/hypoxia.html</ref> Generally, hypoxic waters have dissolved oxygen concentrations of less than 2 or 3 [[ppm]].</onlyinclude><ref name="RE1">US EPA. (August 20, 2015). ''Hypoxia 101'' [Online]. Available: http://water.epa.gov/type/watersheds/named/msbasin/hypoxia101.cfm</ref> When large stretches of open water become hypoxic they are unable to sustain life, and are thus known as dead zones.<ref name="RE2">NOAA. (August 20, 2015). ''Hypoxia'' [Online]. Available: http://oceanservice.noaa.gov/hazards/hypoxia/</ref> Even though fish live underwater, they still need oxygen to survive.

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	==Hydropower==		==Hydropower==
	Since [[~~hydro plant~~\|hydropower facilities]] act as a river obstruction, these dams affect water flow and [[water quality degradation\|quality]]. In particular, these plants can alter normal levels of dissolved oxygen in the rivers. Waters diverted through a hydropower facility tend to be lower in dissolved oxygen than the rest of the ecosystem and thus hypoxic. When this hypoxic water is released downstream, it reduces the overall oxygen content of the rest of the river. This threatens aquatic life below the dam. Because of this, dissolved oxygen monitoring systems are installed to ensure that oxygen levels below and above the dam are relatively similar.<ref name="RE3">Fundamentals of Environmental Measures. (August 21, 2015). ''Monitoring Dissolved Oxygen at Hydropower Facilities'' [Online]. Available: http://www.fondriest.com/environmental-measurements/environmental-monitoring-applications/monitoring-dissolved-oxygen-hydropower-facilities/</ref>		Since [[Hydroelectric facility\|hydropower facilities]] act as a river obstruction, these dams affect water flow and [[water quality degradation\|quality]]. In particular, these plants can alter normal levels of dissolved oxygen in the rivers. Waters diverted through a hydropower facility tend to be lower in dissolved oxygen than the rest of the ecosystem and thus hypoxic. When this hypoxic water is released downstream, it reduces the overall oxygen content of the rest of the river. This threatens aquatic life below the dam. Because of this, dissolved oxygen monitoring systems are installed to ensure that oxygen levels below and above the dam are relatively similar.<ref name="RE3">Fundamentals of Environmental Measures. (August 21, 2015). ''Monitoring Dissolved Oxygen at Hydropower Facilities'' [Online]. Available: http://www.fondriest.com/environmental-measurements/environmental-monitoring-applications/monitoring-dissolved-oxygen-hydropower-facilities/</ref>

	Impoundment-type facilities tend to be more of an issue because they create a [[reservoir]]. In these still waters, it is easy for the water to stratify and create two [[environment]]s in the water. The bottom layer is often hypoxic as a result of poor aeration.<ref name="RE3"/> This oxygen-depleted water is then released downstream.		Impoundment-type facilities tend to be more of an issue because they create a [[reservoir]]. In these still waters, it is easy for the water to stratify and create two [[environment]]s in the water. The bottom layer is often hypoxic as a result of poor aeration.<ref name="RE3"/> This oxygen-depleted water is then released downstream.

J.williams: 1 revision imported

2015-09-03T18:23:25Z

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Jmdonev at 16:17, 3 September 2015

2015-09-03T16:17:04Z

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	[[Category:Done 2015-08-21]]		[[Category:Done 2015-09-05]]
	<onlyinclude>'''Hypoxia''' simply means low [[oxygen]]. ~~Extreme~~ hypoxia~~, with no~~ oxygen is ~~called~~ '''anoxia'''. When there is a low concentration of oxygen in [[water]] it is problematic for ecosystems that rely on this water. Water lacking in oxygen is known as hypoxic water.<ref>USGS. (August 21, 2015). ''Hypoxia Definition'' [Online]. Available: http://toxics.usgs.gov/definitions/hypoxia.html</ref> Generally, hypoxic waters have dissolved oxygen concentrations of less than 2 or 3 [[ppm]].</onlyinclude><ref name="RE1">US EPA. (August 20, 2015). ''Hypoxia 101'' [Online]. Available: http://water.epa.gov/type/watersheds/named/msbasin/hypoxia101.cfm</ref> When large stretches of open water become hypoxic they are unable to sustain life, and are thus known as dead zones.<ref name="RE2">NOAA. (August 20, 2015). ''Hypoxia'' [Online]. Available: http://oceanservice.noaa.gov/hazards/hypoxia/</ref>		<onlyinclude>'''Hypoxia''' simply means low [[oxygen]]. This can apply to a lack of oxygen in [[air]], but in the context of [[hydropower]] hypoxia refers to low concentrations of dissolved oxygen in water. An extreme case of hypoxia is '''anoxia''', when there is no oxygen. When there is a low concentration of oxygen in [[water]] it is problematic for ecosystems that rely on this water. Water lacking in oxygen is known as hypoxic water.<ref>USGS. (August 21, 2015). ''Hypoxia Definition'' [Online]. Available: http://toxics.usgs.gov/definitions/hypoxia.html</ref> Generally, hypoxic waters have dissolved oxygen concentrations of less than 2 or 3 [[ppm]].</onlyinclude><ref name="RE1">US EPA. (August 20, 2015). ''Hypoxia 101'' [Online]. Available: http://water.epa.gov/type/watersheds/named/msbasin/hypoxia101.cfm</ref> When large stretches of open water become hypoxic they are unable to sustain life, and are thus known as dead zones.<ref name="RE2">NOAA. (August 20, 2015). ''Hypoxia'' [Online]. Available: http://oceanservice.noaa.gov/hazards/hypoxia/</ref> Even though fish live underwater, they still need oxygen to survive.

	One hypoxic zone that is particularly concerning is the Gulf of Mexico, which is the largest dead zone in the United States.<ref name="RE2"/> Each year during the summer nutrient-laden fresh water from the Mississippi flows into the gulf. The fresh water is less [[density\|dense]], remaining on top of the gulf water, resulting in a stratification. This prevents oxygen rich surface water from mixing with oxygen poor water lower down, creating hypoxic conditions.<ref name="RE1"/>		One hypoxic zone that is particularly concerning is the Gulf of Mexico, which is the largest dead zone in the United States.<ref name="RE2"/> Each year during the summer nutrient-laden fresh water from the Mississippi flows into the gulf. The fresh water is less [[density\|dense]], remaining on top of the gulf water, resulting in a stratification. This prevents oxygen rich surface water from mixing with oxygen poor water lower down, creating hypoxic conditions.<ref name="RE1"/>
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	==Environmental Impacts==		==Environmental Impacts==
	As expected, the depletion of oxygen in water is not healthy for the ecosystems that rely on the water. Direct effects of hypoxia include numerous deaths of a variety of aquatic animals including fish, mussels, or crabs. Overall, hypoxia decreases the amount of life in hypoxic zones. As well, hypoxia reduces the ability of young fish to find necessary food and habitat to grow and become adults. Thus fish stocks can be reduced or become less stable. Associated with this, any animal that relies on fish for food would be affected and would likely be forced to move.<ref name="RE1"/>		Oxygen exists naturally within water and is extremely important for aquatic life. Oxygen can naturally enter water thruogh a variety of mechanisms, the most common being the process where atmospheric oxygen dissolves and mixes with the water's surface. As well,the presence of moderate amounts of algae result in oxygen being released and dissolved into water during photosenthesis. Finally, fast-moving rivers mix air into the water through a process of aeration.<ref>Chesapeake Bay Program. (September 2, 2015). ''Dissolved Oxygen'' [Online]. Available: http://www.chesapeakebay.net/discover/bayecosystem/dissolvedoxygen</ref>

			As expected, the depletion of oxygen in water is not healthy for the ecosystems that rely on the water. Direct effects of hypoxia include numerous deaths of a variety of aquatic animals including fish, mussels, or crabs. Although it seems counter intuitive, fish and other aquatic organisms drown if there is not suitable oxygen in the water. Despite the fact that they live their life underwater, fish take in dissolved oxygen in water by passing this water through their gills. If there is not suitable oxygen in the water, they are not able to obtain oxygen from the water and suffocate. Overall, hypoxia decreases the amount of life in hypoxic zones. As well, hypoxia reduces the ability of young fish to find necessary food and habitat to grow and become adults. Thus fish stocks can be reduced or become less stable. Associated with this, any animal that relies on fish for food would be affected and would likely be forced to move or starve.<ref name="RE1"/>

	==References==		==References==
	{{reflist}}[[Category:Uploaded]]		{{reflist}}[[Category:Uploaded]]

J.williams: 1 revision imported

2015-08-26T21:31:53Z

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J.williams at 18:50, 24 August 2015

2015-08-24T18:50:44Z

New page

[[Category:Done 2015-08-21]]
<onlyinclude>'''Hypoxia''' simply means low [[oxygen]]. Extreme hypoxia, with no oxygen is called '''anoxia'''. When there is a low concentration of oxygen in [[water]] it is problematic for ecosystems that rely on this water. Water lacking in oxygen is known as hypoxic water.<ref>USGS. (August 21, 2015). ''Hypoxia Definition'' [Online]. Available: http://toxics.usgs.gov/definitions/hypoxia.html</ref> Generally, hypoxic waters have dissolved oxygen concentrations of less than 2 or 3 [[ppm]].</onlyinclude><ref name="RE1">US EPA. (August 20, 2015). ''Hypoxia 101'' [Online]. Available: http://water.epa.gov/type/watersheds/named/msbasin/hypoxia101.cfm</ref> When large stretches of open water become hypoxic they are unable to sustain life, and are thus known as dead zones.<ref name="RE2">NOAA. (August 20, 2015). ''Hypoxia'' [Online]. Available: http://oceanservice.noaa.gov/hazards/hypoxia/</ref>

One hypoxic zone that is particularly concerning is the Gulf of Mexico, which is the largest dead zone in the United States.<ref name="RE2"/> Each year during the summer nutrient-laden fresh water from the Mississippi flows into the gulf. The fresh water is less [[density|dense]], remaining on top of the gulf water, resulting in a stratification. This prevents oxygen rich surface water from mixing with oxygen poor water lower down, creating hypoxic conditions.<ref name="RE1"/>

[[File:hypoxia.jpg|780px|framed|center|Figure 1. A map showing hypoxic zones worldwide. Hypoxic zones are represented as red dots, while eutrophic zones (explained below) are yellow dots. Recovering areas are green.<ref>Eutrophication&Hypoxia. (August 20, 2015). ''World Eutrophic and Hypoxic Coastal Areas'' [Online]. Available: https://www.flickr.com/photos/48722974@N07/5555377863</ref>]]

==Causes==
The amount of oxygen in any body of water varies naturally as a result of oxygen input from the atmosphere and a variety of biological and [[chemical]] processes. The reduction in oxygen concentration can arise as a result of ''stratification'', or the process of less dense freshwater settling on top of heavier seawater. The lack of mixing restricts oxygen to move into the bottom layers, creating deep hypoxic conditions.<ref name="RE2"/>

However, hypoxia occurs most frequently as a result of human-induced factors.<ref name="RE2"/> For example, if there are excess nutrients being introduced to the water - especially [[nitrogen]] or [[phosphorus]] - the water can become hypoxic. The introduction of these nutrients occurs in a process known as [[eutrophication]], where excess nutrients in a system are introduced and promote [[algae|algal]] growth. The hypoxia occurs when algae dies and decomposes, as the decomposition process consumes oxygen. This results in depleted oxygen levels in the water. There are several sources of excess nutrients, including:<ref name="RE1"/>
* Fertilizers from agriculture, golf courses, and suburban lawns
* Erosion of nutrient-rich soil
* Sewage treatment plant discharge
* Deposition of [[atmospheric oxygen]]

==Hydropower==
Since [[hydro plant|hydropower facilities]] act as a river obstruction, these dams affect water flow and [[water quality degradation|quality]]. In particular, these plants can alter normal levels of dissolved oxygen in the rivers. Waters diverted through a hydropower facility tend to be lower in dissolved oxygen than the rest of the ecosystem and thus hypoxic. When this hypoxic water is released downstream, it reduces the overall oxygen content of the rest of the river. This threatens aquatic life below the dam. Because of this, dissolved oxygen monitoring systems are installed to ensure that oxygen levels below and above the dam are relatively similar.<ref name="RE3">Fundamentals of Environmental Measures. (August 21, 2015). ''Monitoring Dissolved Oxygen at Hydropower Facilities'' [Online]. Available: http://www.fondriest.com/environmental-measurements/environmental-monitoring-applications/monitoring-dissolved-oxygen-hydropower-facilities/</ref>

Impoundment-type facilities tend to be more of an issue because they create a [[reservoir]]. In these still waters, it is easy for the water to stratify and create two [[environment]]s in the water. The bottom layer is often hypoxic as a result of poor aeration.<ref name="RE3"/> This oxygen-depleted water is then released downstream.

==Environmental Impacts==
As expected, the depletion of oxygen in water is not healthy for the ecosystems that rely on the water. Direct effects of hypoxia include numerous deaths of a variety of aquatic animals including fish, mussels, or crabs. Overall, hypoxia decreases the amount of life in hypoxic zones. As well, hypoxia reduces the ability of young fish to find necessary food and habitat to grow and become adults. Thus fish stocks can be reduced or become less stable. Associated with this, any animal that relies on fish for food would be affected and would likely be forced to move.<ref name="RE1"/>

==References==
{{reflist}}[[Category:Uploaded]]