Essay on Harris: Volcano and Large Volcanic Eruptions

Submitted By jah247
Words: 1543
Pages: 7

The Earth system consists of the geosphere, atmosphere, hydrosphere and biosphere, and can be regarded as a large-scale example of Le Chatelier's Principle where systemic perturbations are mitigated through complex feedbacks to eventually establish an amended equilibrium. The geosphere impacts the other spheres as it regulates uniformitarianism through volcanism, while also providing the physical interface between the lithosphere and organic subaerial constituents of the earth system in the form of regolith; thereby facilitating biotic subsistence and terrestrial feedback. Considering spatiotemporal impacts of volcanism are inherently interconnected concerning volcanism, a temporal scale will be implemented to define such feedbacks between parameters of the earth system, as the Gaia Hypothesis postulates.

It is evident that short-term impacts (<1 year) deriving from major eruptions are interrelated and therefore impact the Earth systems’ spheres in a variety of complex ways. For instance, ejecta that fails to penetrate the stratosphere exacerbates tropospheric meteorological activity in the succeeding weeks as tephra acts as a nuclei for water vapour, which is subsequently precipitated out (10). This rain encompasses particulate sulphide matter that impacts the biosphere (via regolith) by acidifying soil pH levels, that in turn kills enzymes and insects while intensifying leaching of essential nutrients (Mg, Ca) through clay degradation (12). Phreatic hydromagmatic eruptions also have the capacity to produce toxic fog (vog) that acidifies the immediate environment (11). Ejected ash particles create respiratory complications for animals and may impede photosynthesis and stomatal exchange in flora. Additionally, tephra can inhibit the infiltration capacity of soil leading to biological stress (9).

Vulnerable vegetation unable to survive initial impacts undermine the hydrosphere as water storage is reduced, while canopy interception and evapotranspiration is eliminated. Moreover, pyroclastic incendiaries can destroy flora, which reduces habitat and the capacity of terrestrial carbon sequestration. Subsequently, vegetation removal leads to excessive sediment flux through increased rill, gully and sheetwash erosion, further altering the local hydrogeomorphology. Furthermore, large geospheric flow events (lahars, pyroclastic flows, lava flows etc.) have the ability to remove watershed divides and obstruct alluvial systems, consequently providing the catalyst for debris flows and channel avulsion (8). Likewise, volcanogenic tsunamis can be instigated when submarine eruptions, flows, or volcanic bombs impact large water bodies initiating biodiversity reduction through habitat destruction, salinization and the introduction of invasive species (14). In the oceans, iron-rich deposits create chlorophyll anomalies, the proxy for phytoplankton abundance, which generate prodigious blooms; thus enhancing biological production, while offsetting atmospheric carbon saturation (9). Soils are also enriched by aeolian-dispersed nutrients over short time frames.

Sustained degassing of fine sulphate matter has proven to have temporally minute, yet spatially vast effects upon the Earths’ latent heat flux through limiting the solar energy budget, which intrinsically weakens endothermic evaporation. A sea surface temperature reduction equates to lower evaporation, therefore catchment influx is disrupted, and alluvial velocity is reduced creating dynamic consequences for the geosphere, hydrosphere and biosphere respectively. Sediment aggradation may result from waning flows, which forces the mass balance between sediment deposition and entrained clasts into disequilibrium. Secondly, lowering the groundwater table through reduced precipitation depletes aquifers, placing stress on the hydrosphere and biosphere collectively. Moreover, the inability of waning flows to dilute nutrients and provide habitat for riparian and aquatic fauna is acutely…