کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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6432770 | 1635445 | 2014 | 8 صفحه PDF | دانلود رایگان |
Field and laboratory experiments were performed to examine dissolution rates of limestone in stream flow. Field experiments were conducted in three stream sites (A-C) with different lithological or hydrological settings around a limestone plateau in the Abukuma Mts., Japan. Sites A and B are allogenic streams, which flow from non-limestone sources into dolines, and site C has a karst spring source. Tablets made of limestone from the same plateau with a diameter of 3.5 cm and a thickness of 1 cm were placed in the streams for 3 years (2008-2011) where alkalinity, pH and major cation concentrations were measured periodically. The saturation indices of calcite (SIc) of stream water were â 2.8 ± 0.4 at site A, â 2.5 ± 0.4 at site B and â 0.5 ± 0.4 at site C. Annual weight loss ratios for tablets were extremely high at site A (0.11-0.14 mg cmâ 2 dâ 1), high at site B (0.05 mg cmâ 2 dâ 1), and low at site C (0.005 mg cmâ 2 dâ 1). The contrasting rates of weight loss are mainly explained by chemical conditions of stream water. In addition, laboratory experiments for dissolution of limestone tablets using a flow-through apparatus revealed that flow conditions around the limestone tablet is another important factor for dissolution in the stream environment. These results revealed that limestone dissolves at a rapid rate where water unsaturated to calcite continuously flows, such as in an allogenic stream.
Journal: Geomorphology - Volume 204, 1 January 2014, Pages 485-492