AirPollution: Difference between revisions

From coraldigest
Jump to: navigation, search
Line 79: Line 79:
Particulates sources of cloud nuclei, thereby increasing cloud formations in the atmosphere. Larger particulates form rain clouds while smaller particulates form light-scattering clouds and thus have a cooling effect. <ref name = "qw"> "Secret of Cloud Formation" Web. Apr. 2015. Retrieved from http://www.pbs.org/wgbh/nova/next/earth/cloud-formation-in-the-amazon/. </ref>. Additional cloud formation than what is natural and considered regular in an ecosystem such as the coral reefs can cause detrimental effects. For example, clouds are able to block and reflect sunlight, therefore depriving zooxanthellae from the integral light source that they need to create energy.
Particulates sources of cloud nuclei, thereby increasing cloud formations in the atmosphere. Larger particulates form rain clouds while smaller particulates form light-scattering clouds and thus have a cooling effect. <ref name = "qw"> "Secret of Cloud Formation" Web. Apr. 2015. Retrieved from http://www.pbs.org/wgbh/nova/next/earth/cloud-formation-in-the-amazon/. </ref>. Additional cloud formation than what is natural and considered regular in an ecosystem such as the coral reefs can cause detrimental effects. For example, clouds are able to block and reflect sunlight, therefore depriving zooxanthellae from the integral light source that they need to create energy.


==Greenhouse gases==
Greenhouse gases can cause both ocean acidification and coral bleaching.
'''Ocean Acidification'''
[[File:pmel-oa-imageee.jpg|thumb|left|<ref name = "qq"> "Ocean Acidification: The Other Carbon Dioxide Problem" Web. Apr. 2015. Retrieved from http://www.pmel.noaa.gov/co2/story/Ocean+Acidification. </ref>]]
[[Ocean Acidification|Ocean Acidification]]
Ocean acidification is caused by an excess of carbon dioxide emitted into the atmosphere. The extra CO2 will be absorbed by the ocean, and will react with the water to release a hydrogen ion, thus lowering the pH. The lowered pH will dissolve the calcium carbonate skeleton of the corals. The pH scale is a method of measuring the acidity of fluids, the lower the number is, the higher the acidity. It is important to note that each single integral difference on the scale is equivalent to a ten magnitude of difference, meaning that a fluid with a pH of 4 is actually 10 times more acidic than a fluid with a pH of 10 <ref name = "ss"> "pH scale" Web. Apr. 2015. Retrieved from <http://elmhcx9.elmhurst.edu/~chm/vchembook/184ph.html>. </ref>. Over Earth's history, the oceans have maintained an average pH of around 8.2, however in recent years the average pH has dropped to 8.1 - this is a severe change when factoring in the magnitude differences of the pH scale as well as the natural buffering effect of the ocean <ref name = "jj"> "Ocean Acidification" Web. Apr. 2015. Retrieved from <http://ocean.nationalgeographic.com/ocean/critical-issues-ocean-acidification/>. </ref>. This means that the oceans have been resisting the pH changes through the process of dissolving calcium carbonate to form bicarbonate with the dissolved carbon dioxide. The lack of calcium carbonate itself is a great negative impact on the ecosystem, but at least the pH change isn't so great as to greatly affect the various other species. However, once the calcium carbonate supply of the ocean has been depleted, pH change will be exacerbated even more.
[https://www.youtube.com/watch?v=GL7qJYKzcsk Acidification Video]
'''Coral Bleaching'''
[[Coral Bleaching|Coral Bleaching]]
[[File:figB1.jpg|thumb|right|<ref name = "ww"> "Climate Change at the National Academies" Web. Apr. 2015. Retrieved from https://nas-sites.org/americasclimatechoices/more-resources-on-climate-change/climate-change-evidence-and-causes/climate-change-evidence-and-causes-figure-gallery/figb1/. </ref>]]
Coral bleaching occurs when zooxanthellae - the symbiont living within the corals - are expelled due to increased heat of the ocean. Since zooxanthellae are what give coral its color, the loss of these symbionts results in the loss of color in coral, giving it a bleached appearance. The loss of the zooxanthellae can also lead to coral death, since those symbionts are what provide the coral with its energy.
[[File:bleaching1.jpg|thumb|right|<ref name = "ee"> "Coral Bleaching" Web. Apr. 2015. Retrieved from <http://www.coralreefecosystems.net/index.php?page=researchgroup&groupid=2>. </ref>]]
Due to the warming conditions of recent years caused by increase greenhouse gases in the atmosphere, not only have terrestrial ecosystems experienced an increase in temperature, but the oceans have also experienced that as well. In fact, 2014 was the warmest year, with the ocean temperature surpassing the 20th century average by 1.24 degrees Fahrenheit <ref name = "jkjk"> "2014 Confirmed as Hottest Year on Record" Web. Apr. 2015. Retrieved from <http://news.nationalgeographic.com/news/2014/01/150116-2014-hottest-year-global-warming-climate-science/>. </ref>. These abnormal temperatures are the cause of zooxanthellae being expelled.
It is important to note that cold water can cause bleaching as well, although it is much less common due to the general upward trend of our global temperature. In January of 2010, decreased temperature in the waters of Florida Keys caused bleaching and some coral death <ref name = "mm"> "What is Coral Bleaching?" Web. Apr. 2015. Retrieved from <http://oceanservice.noaa.gov/facts/coral_bleach.html>. </ref>.
=== Major Greenhouse Gases === <ref name = "hihi">"Main Greenhouse Gases?" Web. Apr. 2015. Retrieved from <http://www.c2es.org/facts-figures/main-ghgs>. </ref>.
1. Water vapor
2. Carbon dioxide (CO2)
• Burning of fossil fuels and deforestation are the main sources
• Prior to the Industrial Revolution, the concentration of CO2 in ice sheets was between 200 and 300 ppm. Since the Industrial Revolution, the rate of increase is about 0.5% per year. Today, the concentration of CO2 is about 380 ppm and it is expected to rise to about 450 ppm by 2050.
• 50 to 60% of anthropogenic greenhouse effect is attributed to this gas
3. Methane (CH4)
• Amount of CH4 in atmosphere has more than doubled in past 200 years.
• Contribute approximately 12-20% of the anthropogenic greenhouse effect.
• Major Sources: termites, freshwater wetlands (decomposing plants in oxygen-poor environments produce and release methane as decay product), seepage from oil fields, and seepage from methane hydrates. Anthropogenic sources: emissions from landfills, burning of biomass, production of coal and natural gas, and agricultural activities.
4. Nitrous oxide (N2O)
• Increasing and has a long residence time, so if emissions were reduced, elevated concentrations of nitrous oxide would persist for at least several decades
• 5% of anthropogenic greenhouse effect
• Sources: application of fertilizers, burning of fossil


== Additional Educational Materials==
== Additional Educational Materials==

Revision as of 14:27, 27 April 2016

Air Pollution

The effects of air pollution on coral reefs are getting more and more attention over the decades, as the serious threats caused by air pollution to the world's coral reefs are now widely recognized by scientists. It is important to understand how corals are in risks because of air pollution.

Source of Pollution

Volcano eruptions are a source of air pollution [1]

Generally, air pollution is any substance that people introduce into the atmosphere that has damaging effects on living things and the environment[2].

Both human activities and natural processes can create air pollution.

There are various sources of human-related air pollution. Major sources include:

  • industrial waste gas composed of smoke, sulfides, nitrides, organic compounds, halides, carbides, etc.
  • vehicle exhaust composed of carbon monoxide, sulfur dioxide, nitric oxides, and hydrocarbon as a result of burning fuels
  • other pollutants created in human’s daily life, such as CFCs, ozone, and so on.

Some natural processes are also responsible for the air pollution. One major source of natural air pollution is the volcanic activities, where tons of pollutants including carbon dioxide, sulfuric oxides, and macro-particles are ejected into the atmosphere by volcanoes. Wildfires, desertification and emission of methane by animals are also major sources of the pollution.

Impacts of Pollution

An example of coral bleaching [3]

How will the air pollution effect the coral reefs in the ocean?

  1. The fine airborne particles, or aerosols, can scatter incoming sunlight and create cloudier, more reflective conditions[4]. These macro-particles floating in the air can reduce the amount of sunlight reaching the sea surface in a large scale. And if the amount of aerosols is too large, the haze may form and block even more sunlight. As a result, the photosynthesis of the single-celled algae, zooxanthellae, which keeps a symbiotic relation with coral, will reduce sharply. Thus, the amount of nutrition the coral can obtain from zooxanthellae in order for its growth will reduce. As less sunlight reaches the sea, the water temperature will fall, worsening the situation even more. The growth rate of coral will be limited due to the insufficient sunlight and the cold water temperature. Coral bleaching, a process caused by the expulsion of zooxanthellae, will occur if the water gets too cold, possibly leaving the coral to death[5].
  2. Global warming is another big threat to coral reefs. The rapid buildup of greenhouse gases (GHGs) in the atmosphere during the past centuries has brought significant contribution to the climate change in the world. As the climate gets hotter, the rising water temperature of ocean will cause large scale of coral bleaching. Massive corals will die as a result of the change of climate. The increasingly frequent extreme weathers and disasters such as hurricanes and tropical storms due to the change of climate and rise of water temperature will bring direct physical damages to coral reefs. Rising sea level due to global warming will make the situation even worse[5].
  3. It is reported that, many serious coral diseases are also related to air pollution. Scientists have found that many pathogens will travel with the aerosols and spread over the world. One example is the African dust traveled with wind from deserts in Africa. Every year, several hundred million tons of African dusts are transported across the Atlantic to the Caribbean, Central and South America[6]. Pathogens like fungus Aspergillus sydowii, which causes the sea-fan diseases, and sphingomonas, which is the cause of white plague, can travel with the dusts and move to the other side of the earth, causing catastrophic problems to local corals[7].
  4. Air pollution is also responsible for ocean acidification. Ocean water normally contains carbonic acid because carbon dioxide in the atmosphere can be dissolved by the water. However, if the amount of carbon dioxide continues to increase, the chemistry of ocean water will be altered as the water contains more carbonic acid. As the water becomes more acidic, the amount of aragonite -- a mineral used by corals in reef building -- in the water will decrease and the ability of corals to build reefs by laying down their limestone skeletons will also be limited. Thus, the reversal of reef building will slow down and the loss of reef in the future may be a result[5].

The Global Dust Cycle

Sources and Sinks of the Global Dust Cycle [8]

The global dust cycle is a geochemical process similar to the carbon or water cycle. Each year 2000 Mt of dust is emitted into the atmosphere from various regions around the world. Dust is swept off of deserts, carried across the globe and deposited in different locations. It is important to note that this is a naturally occurring and benign cycle that has existed as a part of Earth's climate for thousands of year. However, since the 1970s the impact of dust on coral reefs has become more severe. Dust affects soil formation in the rainforest, global climate, glacial cycles and the transport of micronutrients. While further research is of course needed on this relatively new subject, two variables have been identified as having led to the transformation of dust into a dangerous force for coral reeds and ecosystems. These factors are quantity of the dust and the chemical composition of the dust. Both of these variables have been impacted by human activity and global warming [9] .

Human Impacts

The transfer of African dust across the Atlantic Ocean is a natural phenomenon, but in the last 45 years, humans have altered the chemical and physical composition of dust to the point where dust now poses health risks for coral reef ecosystems and human populations. Human practices have increased the quantity of global dust and the chemical composition of dust.

  • Increase in the quantity of dust-

Global temperature increases have left once fertile soil dry and sandy. This is especially true in the Sahara and Sahel regions of Africa. Further, human activity has played a significant role in the increase of dust that is carried across the Atlantic Ocean. Desertification and changing land-use patterns lead to further loss of habitable land, and ultimately to an increase in dust replacing topsoil.

  • Change in Chemical Composition of Dust-

Human activities resulting from an agricultural-based economy have transformed dust into a toxic cloud. Dust now carries microbes, heavy metals and pesticides due to biomass combustion, the burning of fossil fuels, the improper disposal of plastics, and the use of pesticides in the source region.


Barbados Mineral Dust Annual Average and Benchmark Caribbean Events [10]

Causes and Effects

  • In the 1970's when a peak in dust pollution was observed in the Caribbean, the Sahel region of Africa was experiencing extreme drought conditions compounded by overgrazing and the drying of Lake Chad [9]. Other possible factors contributing to this episode include global climate change, changes in regional meteorology, and local human activities. Human activities such as burning fossil fuels, burning garbage, and spraying pesticides account for many of the toxins found in dust pollution[10]. Pesticides are a primary concern as they can interfere with animal reproduction, fertilization and immune function. Furthermore, two specific insecticides "chloropyrifos" and "endosulfan" are associated with preventing coral larvae to settle and reproduce[11]. The inorganic dust particulates are made of clay with gypsum and iron oxides that acts as a sponge to absorb other microorganisms. These particles can carry elements such as nitrogen and sulfur that can have harmful affects on surface waters, marine environments, and vegetation. In the Virgin Islands, vegetation has adapted to low nitrogen levels meaning that there could be serious impacts if an abundance of nitrogen is introduced. Sulfur and nitrogen also increase the acidity of water which could also lead to coral bleaching and death [12].

Current Studies

Studies are still being conducted to further investigate where hazardous dust particles are actually coming from as there isn't any exact proof whether the particles are local or foreign. Furthermore, it is also possible that the toxins may not have even come from Africa as the pollution gets mixed in from air all over the world, such as North America.

  • The St. Petersburg Coastal and Marine Science Center has various test sites in the Southern Caribbean (Trinidad and Tobago), St. Croix U.S Virgin Island, and more northern areas [10]. These sites are collecting dust samples to compare the constituent particulates to those found in Africa.

Effects of African Dust on Coral Reefs

Air samples collected in the Virgin Islands during "dust periods" have been found to contain 2-8 times as many organisms as air samples collected during not dust periods. This indicates that the dust is bringing with it harmful organisms that negatively impact coral [13].


For example, a fungus that exists in African spoil has been identified in the Virgin Islands and has caused a spike in Sea-Fan disease. Other coral diseases linked to African dust include:

  • Black-band disease
  • White plague
  • White pox
  • Bacterial included bleaching
  • Pink spot disease

Effects of African Dust on Human Health

Dust has had a negative impact on the health of humans living in the surrounding Caribbean and Gulf regions. For example, Gene Shinn of the USGS says that asthma rates in the Caribbean are among the highest in the world. Specifically, asthma in Trinidad and Barbados has increased 17 times since the early 1970s. [10]

Asthma rates in Tampa Bay, Florida have seen a similar spike. Gene Shinn reports that close to half of the particles in the air breathed in the Tampa area originate from Africa.

Other human diseases linked to African dust include influenza, SARS, and tuberculosis.


Details on Types of Air Pollution

Particulates

[3]

Particulate matter are small particles ranging from 2.5 micrometer to 10 micrometer in diameter. These particles can come from anywhere: smokestacks, car emissions, farming, industrial processes, volcanic eruptions, etc. [14]. [15].

Particulates sources of cloud nuclei, thereby increasing cloud formations in the atmosphere. Larger particulates form rain clouds while smaller particulates form light-scattering clouds and thus have a cooling effect. [16]. Additional cloud formation than what is natural and considered regular in an ecosystem such as the coral reefs can cause detrimental effects. For example, clouds are able to block and reflect sunlight, therefore depriving zooxanthellae from the integral light source that they need to create energy.


Additional Educational Materials

Presentation

Error creating thumbnail: /bin/bash: line 1: /usr/bin/gs: No such file or directory /bin/bash: line 1: /usr/bin/convert: No such file or directory

Lesson Plan

Media:African_Dust_Lesson_Plan_(2).pdf ‎

References

  1. https://commons.wikimedia.org/wiki/File:Shishaldin_Volcano_eruption_1999.jpg
  2. "Air Pollution." National Geographic. N.p., n.d. Web. 13 Apr. 2014. Retrieved from http://environment.nationalgeographic.com/environment/global-warming/pollution-overview/
  3. 3.0 3.1 "Coral Bleaching: Global Green House" Web. Apr. 2015. Retrieved from http://www.global-greenhouse-warming.com/coral-bleaching.html. Cite error: Invalid <ref> tag; name "ii" defined multiple times with different content
  4. Kwiatkowski, Lester. "Air Pollution Casts a Cloud over Coral Reef Growth." The Conversation. N.p., 8 Apr. 2013. Web. 16 Apr. 2014. Retrieved from http://theconversation.com/air-pollution-casts-a-cloud-over-coral-reef-growth-13319?utm_medium=email&utm_campaign=Latest+from+The+Conversation+for+9+April+2013&utm_content=Latest+from+The+Conversation+for+9+April+2013+CID_108dc635aa87df8ce801c5c3cc26a4cd&utm_source=campaign_monitor&utm_term=Air%20pollution%20casts%20a%20cloud%20over%20coral%20reef%20growth
  5. 5.0 5.1 5.2 Burke, Lauretta Marie., and Jonathan Maidens. Reefs at Risk in the Caribbean. Washington, D.C.: World Resources Institute, 2004. Print.
  6. "Asthma, Coral and African Dust." PBS. PBS, n.d. Web. 16 Apr. 2014. Retrieved from http://www.pbs.org/strangedays/episodes/onedegreefactor/experts/africandust.html
  7. Shinn, Eugene A., Garriet W. Smith, Joseph M. Prospero, Peter Betzer, Marshall L. Hayes, Virginia Garrison, and Richard T. Barber. "African Dust and the Demise of Caribbean Coral Reefs." Geophysical Research Letters 27.19 (2000): 3029. Print.
  8. "Dust cycle: An emerging core theme in Earth system science " Web. Apr. 2016. Retrieved from http://dx.doi.org/10.1016/j.aeolia.2011.02.001.
  9. 9.0 9.1 Yaping Shao, Karl-Heinz Wyrwoll " Dust cycle: An emerging core theme in Earth system science ." Aeolian Research, Volume 2, Issue 4, 2011, 181–204. Retrieved from http://dx.doi.org/10.1016/j.aeolia.2011.02.001.
  10. 10.0 10.1 10.2 10.3 "When the Dust Settles." May 2001. Web. <http://earthobservatory.nasa.gov/Features/Dust/>
  11. Handwerk, Brian. "Tainted African Dust Clouds Harm U.S., Caribbean Reefs." National Geographic News. 14 July 2008. Web. 23 Feb. 2015. Retrieved from http://news.nationalgeographic.com/news/2008/07/080714-africa-clouds.html.
  12. "Air Pollution Impacts: Virgin Islands National Park." National Park Service. 15 Jan. 2015. Web. 23 Feb. 2015. Retrieved from http://www.nature.nps.gov/air/Permits/aris/viis/impacts.cfm
  13. “The Effects of African Dust on Coral Reefs and Human Health.” USGS. April 2014. Web. <http://coastal.er.usgs.gov/african_dust/index.html>
  14. "Basic Information" EPA. Environmental Protection Agency, Web. Apr. 2015. <http://www.epa.gov/pm/basic.html>.
  15. "Particulate Matter: Little things can cause big problems", Web. Apr. 2015 <http://www.hcdoes.org/airquality/monitoring/pm.htm#Where%20does%20particulate%20matter%20come%20from>.
  16. "Secret of Cloud Formation" Web. Apr. 2015. Retrieved from http://www.pbs.org/wgbh/nova/next/earth/cloud-formation-in-the-amazon/.
Cookies help us deliver our services. By using our services, you agree to our use of cookies.