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单词 peat
释义
peat

Biology
  • A mass of dark-brown or black fibrous plant debris produced by the partial decay of vegetation, such as mosses of the genus Sphagnum, in acidic wet places (see hydrosere). It may accumulate in depressions. When subjected to burial and hence pressure and heat, it may be converted to coal. Peat is often extracted and used to improve soil and as a fuel. However, peat is a globally significant store of carbon, and peatlands are important for retaining water and as wildlife habitats. Hence, there is concern about the impact of extracting peat for horticulture and other uses.


Geology and Earth Sciences
  • An organic soil or deposit; in Britain, a soil with an organic soil horizon at least 40 cm thick. Peat formation occurs when decomposition is slow owing to anaerobic conditions associated with waterlogging. Decomposition of cellulose and hemicellulose is particularly slow for Sphagnum plants, which are characteristic of such sites, and hence among the principal peat-forming plants. Fen and bog peats differ considerably. In fen peats the presence of calcium in the groundwater neutralizes acidity, often leading to the disappearance of plant structure, giving a black, structureless peat. Bog peats, formed in much more acidic waters, vary according to the main plants involved. Species identification of constituents (including animals as well as plants) remains possible after long periods. Recent bog-moss (Sphagnum) peat is light in colour, with the structure of the mosses perfectly preserved.


Geography
  • A mass of dark brown or black, partly decomposed plant material, formed in waterlogged ground, where temperatures are low enough to slow down the decomposition of plant residues. It is characteristically found in cold climates, and as a relict feature in temperate zones. See Turetsky et al. (2007) Glob. Change Biol. 13 on climate change and peatland. Peat may be used as fuel, and is widely used by gardeners; so much so that peat bogs are now under threat. See M. Evans and J. Warburton (2007).


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