Systematization of Karst Processes in Japan

为了弄清日本7个观测站(旭川、浅间、七步、秋吉台、四国小名原、琉球和南北道)1993-1997年间岩溶过程的区域性和年际波动，测定了石灰岩片岩的溶解失重率。这项研究在1995、1996和1997年得到了助学金的支持。研究结果如下：(1)在本州岛，日本南部地区的解决率较高。但南方是个例外，因为夏季存在干旱期。(2)在每个测站，土壤层A_3和B_2层的溶解速率比地面以上空气中的1.5m高2-3倍。(3)在观测的5年中，最高的溶蚀速率出现在1993年的湿润年，最小的溶蚀速率出现在1994年的干热年，几乎所有观测点都出现了这种现象。(4)大气中5年的(石灰岩溶蚀速率)与(水分盈馀，WS-水分亏缺，WD)的相关系数最高。(5)土壤A_3层和B_2层石灰岩溶解速率与年降水量的相关系数为5年来最高。经过3-4天的20毫米降雨量，土壤中的CO_2含量表现出极高的值。以上(1)~(6)项说明了日本岩溶作用的系统化。

Weight loss of limestone tablets by solution has been measured in order to clarify the regionality and year to year fluctuation of the karst processes at 7 observation stations (Asahikawa, abukuma, Chichibu, Akiyoshidai, Sikoku-onogahara, Ryugado and Minamidaito) in Japan during 1993-1997. This study was supported by Grant-in-aid in 1995,1996, and 1997. The results obtained are as follows :(1) In Honshu, solution rates are higher in the southern parts of Japan. However, Minamidaito is an exception, because of existence of dry period during summer.(2) In each station, the solution rates in A_3 and B_2 horizon of soil layrs are 2-3 times higher than 1.5m in the air above the ground. This means that the "covered karst processes" are 2-3 times higher than the "bare karst processes".(3) During the 5 years measured, the highest solution rates were occurred in 1993, a wet year and on the contrary, the smallest solution rates were occurred in 1994, a dry and hot year, which appeared at the almost all observation points.(4) Correlation coefficient between (solution rate of limestone) and (water surplus, WS-water deficit, WD) for the 5 years is the highest in the air, 1.5m above the ground.(5) Correlation coefficient between (solution rate of limestone in A_3 horizon and B_2 horizon of soils) and (annual precipitation) is the highest for the 5 years measured.(6) In the soils, high CO_2 contents have been observed during the warmer period of the years. After 3-4 days of 20mm rainfall, CO_2 contents in the soils show extremely high value. It is considered that these water contents and high CO_2 values resulted in karstification strongly.In conclusion, the systematization of karst processes in Japan has been made clear as written in (1)-(6) above.