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|標題:||The functionality evaluation of aeolian dust prevention using macromolecule material|
|摘要:||The prevention of aeolian dust is an important environment issue and one kind of soil and water conservation problem. How to rapidly construct the wet cover which could stabilize the soil structure on the fine particle and dry river bed is a key point technique for aeolian dust precaution. With literature review, the Polyvinyl Alcohol which is broad application, no toxin, easy hydrolysis and low effect for soil pH value was selected as experiment material. The results showed a positive relation between concentration of PVA solution and stability of aggregation. In the initial stage, the soil particle can aggregate by the bond energy of hydrogen. After water evapotranspiration, the bond of soil aggregation can construct with PVA molecule and soil cation and provide stronger erodibility. Besides, when the concentration of PVA is higher than 4%, the soil surface is subject to become crust after evapotranspiration and the infiltration potential is low which causes the surface runoff increase. As a result of crust break, the sediment below the curst is vulnerable to erosion and aeolain dust occurrence under the strong wind. However, when the concentration of PVA is lower than 3%, the infiltration potential can increase because of the van der Waals' force between PVA molecules. The water can infiltrate to 20 cm soil depth, root system depth, and the PVA provides the great ability of synthetic soil conditioners. The experiments of germination rate with different PVA concentration and 0.5% xanthan gum addition were compered. The results show that the great germination rate is PVA concentration lower 1% and xanthan gum addition is no significant for germination rate.|
河川揚塵防治乃近年受到重視之環境議題，更是水土保持問題之一環。如何於細顆粒之乾 燥河床，快速形成水分不易散失之濕潤層，使土砂成為穩定之團粒，將是抑制河川揚塵極為關 鍵之技術。本研究經文獻回顧，採用途廣、無毒害、易水解、對土壤 pH 值影響極微之高分子 材料聚乙烯醇(P.V.A.)做為試驗材料。結果顯示，PVA 水溶液濃度與土砂團粒穩定度成正相關， 初期土砂藉由水分子氫鍵鍵能形成團粒化，水分蒸散後，團粒轉換為 PVA 分子與土壤中陽離 子鍵結，可提供更強抗風蝕能力。此外，當 PVA 濃度高於 4%時，水分蒸散後土表易產生結殼， 入滲勢能極低，地表逕流增加，硬殼破裂後，下層土砂仍易受風力吹襲產生揚塵。惟當 PVA 濃度降至 0.3%時，透過分子間凡德瓦爾力作用入滲勢能反而增加，可使水份可滲透至 20 公分 之土壤深度，即一般根系生長深度，充分發揮最佳土壤改良(synthetic soil conditioners)功能。種 籽發芽率對於不同 PVA 濃度與添加 0.5％之三仙膠進行對照試驗，結果發現，PVA 濃度低於 1% 時，有最佳發芽率，三仙膠添加與否對種籽發芽無明顯差異。
|Appears in Collections:||第49卷 第01期|
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