Two causes for runoff initiation on microbiotic crusts: Hydrophobicity and pore clogging
Two causes for runoff initiation on microbiotic crusts: Hydrophobicity and pore clogging
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DOI：
10.1097/00010694-199901000-00004
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发表时间：
1999-01-01
期刊：
影响因子：
--
通讯作者：
Vonshak, A
中科院分区：
文献类型：
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作者：
Kidron, GJ;Yaalon, DH;Vonshak, A
疏水性和孔隙堵塞被认为是两种机制，负责产生径流的微生物结皮覆盖沙丘砂，虽然天然微生物结皮在Hallamish沙丘领域（内盖夫沙漠，以色列）没有显示出任何疏水性，这是不与天然结皮的情况下，在实验室中进行长时间的连续潮湿。在实验室中生长的单藻结皮在干燥时也显示出高疏水性。然而，一旦表面被润湿，疏水性就消失了。径流单藻实验室生长的结壳时，得到（一）干结壳表现出疏水特性和（二）湿结壳不再表现出斥水性。虽然径流产生引起的疏水性是预期的，它建议径流启动时，结壳不表现出任何疏水性源于高吸水性和膨胀的胞外多糖蓝藻鞘引起孔堵塞。地壳的多层结构和细丝迁移到表面可能会加剧孔隙堵塞。实验及其解释得到了对已发表数据的重新解释的支持。
Hydrophobicity and pore clogging are suggested as two mechanisms responsible for generating runoff over microbiotic crusts overlying dune sand, Although natural microbiotic crusts in the Hallamish dune field (Negev Desert, Israel) did not show any hydrophobicity, that was not the case with natural crusts subjected to long periods of continuous wetness in the lab. Monoalgal crusts, grown in the lab, also showed high hydrophobicity when dry. The hydrophobicity vanished, however, once the surface was wetted. Runoff on monoalgal lab-grown crusts was obtained when (i) the dry crust exhibited hydrophobic properties and (ii) the wetted crust no longer showed water repellence. Although runoff generation caused by hydrophobicity is expected, it is suggested that runoff initiation when the crusts do not exhibit any hydrophobicity stems from the high water absorption and swelling of the exopolysaccharide cyanobacterial sheaths causing pore clogging. The multi-layered structure of the crust and filament migration to the surface may enhance pore clogging. The experiments and their interpretation are supported by reinterpretation of published data.