| Abstract from DBPedia | The pedosphere (from Greek πέδον pedon "ground" or "earth" and σφαῖρα sphaira "sphere") is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. The pedosphere is the skin of the Earth and only develops when there is a dynamic interaction between the atmosphere (air in and above the soil), biosphere (living organisms), lithosphere (unconsolidated regolith and consolidated bedrock) and the hydrosphere (water in, on and below the soil). The pedosphere is the foundation of terrestrial life on Earth. The pedosphere acts as the mediator of chemical and biogeochemical flux into and out of these respective systems and is made up of gaseous, mineralic, fluid and biologic components. The pedosphere lies within the Critical Zone, a broader interface that includes vegetation, pedosphere, groundwater aquifer systems, regolith and finally ends at some depth in the bedrock where the biosphere and hydrosphere cease to make significant changes to the chemistry at depth. As part of the larger global system, any particular environment in which soil forms is influenced solely by its geographic position on the globe as climatic, geologic, biologic and anthropogenic changes occur with changes in longitude and latitude. The pedosphere lies below the vegetative cover of the biosphere and above the hydrosphere and lithosphere. The soil forming process (pedogenesis) can begin without the aid of biology but is significantly quickened in the presence of biologic reactions, where it forms a soil carbon sponge. Soil formation begins with the chemical and/or physical breakdown of minerals to form the initial material that overlies the bedrock substrate. Biology quickens this by secreting acidic compounds that help break rock apart. Particular biologic pioneers are lichen, mosses and seed bearing plants, but many other inorganic reactions take place that diversify the chemical makeup of the early soil layer. Once weathering and decomposition products accumulate, a coherent soil body allows the migration of fluids both vertically and laterally through the soil profile, causing ion exchange between solid, fluid and gaseous phases. As time progresses, the bulk geochemistry of the soil layer will deviate away from the initial composition of the bedrock and will evolve to a chemistry that reflects the type of reactions that take place in the soil.土壌圏（どじょうけん、英語: pedosphere）とは、地球の土壌から成る部分を指す。英語のpedosphereは古代ギリシア語で「土」や「地球」を意味するπέδον（pedon）と「圏」を意味するσφαῖρα（sphaira）に由来している。土壌圏は岩石圏、水圏、大気圏、生物圏と接触し、これらの圏と動的相互作用を及ぼす。また、土壌圏は地上の生命の基盤となっている。 土壌圏では接触するそれぞれの圏と地球の化学的・生物地球化学的な流動の媒介作用が行われており、土壌圏は鉱物、気体、液体、生物から構成されている。土壌圏は地上の植生や、帯水層、レゴリス、基盤岩とを構成し、様々な化学変化が起こる。 また地球全体のシステムとして、任意のすべての土壌の作る環境は気候的要因や地理的要因、生物的要因、人為的要因によって変化する。 土壌圏は生物圏の植生の下と水圏やリソスフェアの上に存在する。土壌生成は生態系が存在せずとも起こり得るが、生物学的化学反応により土壌生成の速度は大幅に上がる。土壌生成は化学的または物理学的な鉱物の破壊が始まり、そして岩盤上を覆う物質を作ることにより起こる。地衣類やコケ類、種子植物などの生物由来の酸は岩石の分解を早める。しかし、多くの無機反応によっても多くの物質が作られ、それらの物質が若い地層を作る。風化作用とによる生成物が堆積すると、連続した地層の間では土壌断面を介して流体が広がり、固相・液相・気相間でのイオン交換を起こす。時間の経過とともに、地層の組成は土壌中で起こる化学変化に伴って変化する。 (Source: http://dbpedia.org/resource/Pedosphere) |
