The mass-area relationship within cryoconite holes and its implications for primary production
The mass-area relationship within cryoconite holes and its implications for primary production
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DOI：
10.3189/172756411795932038
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发表时间：
2010-01-01
影响因子：
2.9
通讯作者：
Bellas, C.
中科院分区：
文献类型：
--
作者：
Cook, J.;Hodson, A.;Bellas, C.
在冰川和冰盖表面的范围内，描述了冰屑洞中沉积物质量与洞面积之间的线性关系。发现的强关系表明，一些机制调节的沉积物层的厚度占据的“地板”的孔。我们发现，这个调节过程立即响应于新的碎片添加到孔中，并推断它是由横向热传导从碎片到孔壁。这会导致孔被熔化而变宽，然后发生内部碎片的重新分布，通常在单个冰屑颗粒层中产生0.04-0.20 g cm（-2）碎片。在孔加宽过程中碎片层的变薄也减少了自遮蔽，从而最大限度地增加了冰尘对太阳辐射的暴露。我们探讨了生物生产的孔扩大的影响。净光合作用（CO（2）固定）被证明是有利的薄碎片层，而净异养（CO（2）呼吸）发生时，碎片层超过2-4毫米。我们得出结论，cryoconite孔的碳平衡是敏感的碎片的厚度和碎片厚度的热力学平衡有助于生态系统在夏季最大限度地提高初级生产。
linear relationships between the mass of sediment present in a cryoconite hole and the hole area are described for a range of glacier and ice-sheet surfaces. The strong relationships found indicate that some mechanism regulates the thickness of the layer of sediment occupying the 'floor' of the hole. We find that this regulation process responds immediately to the addition of new debris to a hole and infer that it is caused by lateral thermal conduction from the debris to the hole wall. This causes hole widening by melt, and a redistribution of the debris within then takes place, usually resulting in 0.04-0.20 g cm(-2) of debris in a layer of single cryoconite grains. The thinning of the debris layer during hole widening also reduces self-shading and thus maximizes the exposure of cryoconite to solar radiation. We explore the implications of the hole widening for biological production. Net photosynthesis (CO(2) fixation) is shown to be favoured by thin debris layers, whilst net heterotrophy (CO(2) respiration) occurs when debris layers are in excess of 2-4 mm. We conclude that the carbon balance of cryoconite holes is sensitive to the thickness of the debris and that the thermodynamic equilibration of the debris thickness helps the ecosystem to maximize primary production during the summer.