Volcanic eruptions will have major effects on the spheres of planet earth, this page will focus particularly on the atmosphere, biosphere and pedosphere's interaction with volcanic eruptions. The relationship shared between these spheres influence how they react to changes in the geosphere individually and coherently.
Figure 4.0: Illustration of the Atmosphere over the earth (A2ua.com. N.p., 2016. Web. 13 Oct. 2016.)
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Atmosphere
The atmosphere is composed of gases, Nitrogen 78.08%, Oxygen 20.95%, Argon 0.93%, which are constant gases and Water vapour 0-4%, Carbon dioxide 0.037% and other gases 0.003% which are variable (Arbogast, 2014). Constant gases remain the same proportion in the atmosphere as they make up 99.96% of the atmospheres composition. Variable gases change in proportion as they depend on environmental conditions and are less than 1% of the atmospheres current composition (Arbogast, 2014). The atmosphere has a four layered structure with most of its mass in the lower 30km from the earth’s surface. The layers are characterized by temperature, pressure and chemical composition the layers and their distances from the earth’s surface are: the troposphere (8km at the poles and 16km at the equator), stratosphere (50km), mesosphere (80km) and thermosphere (480km) (Arbogast, 2014).
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The most influential, global, internal natural climate change processes are volcanic eruptions as there plumes can dramatically change the composition of the atmosphere. The atmosphere influences the climate and weather patterns that work based on the atmospheres composition and volcanic activity has the ability to make significant changes in the composition of the atmosphere if the eruption is large enough (Arbogast, 2014). Gases ejected into the atmosphere from volcanic eruptions are “water vapor (H2O), carbon dioxide (CO2), sulfur dioxide (SO2), hydrogen chloride (HCl), hydrogen sulfide (H2S), hydrogen fluoride (HF), carbon monoxide (CO), nitrogen (N2), hydrogen (H2), helium (He), methane (CH4), radon (Rn), and heavy metals such lead and mercury”(Heggie, 2013). These ejected chemicals can undergo multiple reactions with atmospheric chemicals, some of which (sulphur aerosols) can cause lower surface temperatures and depletion of ozone (Heggie, 2013). Ramifications of sulphur dioxides can also cause acid rain and in junction with carbon dioxide they can have an effect on the anthrosphere, biosphere and pedosphere (Heggie, 2013). Carbon dioxide is denser than air and is also odorless which makes it a silent killer, it can also accumulate in soils where they can make significant changes to the carbon cycle (Heggie, 2013).
Figure 4.1: Picture of a biome visualizing the values of the biosphere (Y10-environmental-management-sg.wikispaces.com. N.p., 2016. Web. 13 Oct. 2016.)
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Biosphere
The biosphere contains all aspects of life which include humans (anthropshere) because they all share certain features such as cell structure, energy use, reproduction and all a subject of evolution (Bradbury, 1998). However with these similarities comes great diversity throughout the world with dynamic biomes and eco systems forever influencing survival for each organism. The biosphere has a close relationship with the geosphere, hydrosphere and atmosphere as they are responsible for the key elements of life, SPONCH, (Sulphur, Phosphorus, Oxygen, Nitrogen, Carbon and Hydrogen) as well as many of the essential micro nutrient elements (Bradbury, 1998).
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The effects on the biosphere are similar to those on the anthropshere in terms of health and vulnerability to disastrous flows of lava or debris. The most influential impact volcanoes can have on the biosphere is the destruction off habitats, biomes and ecosystems. This is somewhat an indirect effect that volcanic eruptions have on the biosphere, sulphuric acid rain can have an impact on vegetation and small organisms such as primary producers that will evidently have an impact along the food web to the apex predators.
Figure 4.2 : Soil cross section showing Pedospheres position amongst earth system spheres (Soilplantgarden.com. N.p., 2016. Web. 13 Oct. 2016.)
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PedosphereThe surface of the earth, the most outer layer of the lithosphere is called the pedosphere which is composed of soils as a product of processes from the geosphere, atmosphere and biosphere. Fine grained sediments of inorganic minerals are subject from weathering processes that add to soil nutrients, and fine organic material from dead plant and animal life providing a carbon source (Marshak, 2015). Both of these components provide essential elements that support the growth of plants and micro-organisms which have primary link through the food web for the survival of animals at higher trophic levels (Marshak, 2015). The pedosphere plays an essential role in the carbon cycle where rocks reacts with carbon dioxide in the atmosphere through chemical weathering and the carbon dioxide is then consolidated into the minerals where it is then (over time) transported to the ocean (Marshak, 2015).
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Volcanic gas is the number one contributor of carbon dioxide emissions into the atmosphere where it travels through the near surface atmosphere and acts as a greenhouse gas or as an element of chemical weathering, ocean acidification and photosynthesis (Marshak, 2015). The pedosphere “soils can serve as a sink or a source for the greenhouse gas CO2, and changes in soil organic carbon content can therefore have a tremendous effect on the global carbon budget”(Jansen et al., 2011). Volcanic ash has a reasonable amount of aluminium (Al) and iron (Fe) and when deposited on the pedosphere, these minerals play a role in the stabilization of soil organic matter (SOM) (Jansen et al., 2011). Volcanic ash soils having large amounts of SOM allows them to have a greater contribution to carbon storage or release which plays a role in the pedospheres global carbon cycle contribution (Jansen et al., 2011).