矢作川下流低地における完新世の堆積土砂量と蓄積炭素量の時系列的変動

概要

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We estimated time-series variation of stored sediment and carbon as mass during the Holocene for each layer of the Yahagi River Delta, central Japan. We created first raster surface models of ground surface, upper sand (US) top, US bottom, middle mud (MM) bottom and lower sand (LS) bottom using the elevation databases and ground surface models at 7000, 6000, 5000, 4000, 3000 and 2000 cal BP using the ^<14>C ages, then calculated the volume of each layer using ArcView 3D Analyst. The stored sediment of each layer in the study area of 153.9 km^2 was calculated to be 230 Tg for the top mud (TM), 1214 Tg for the US, 1126 Tg for the MM and 665 Tg for the LS using the volume and the bulk density, and the stored carbon was calculated to be 5.69 Tg, 1.46 Tg, 25.89 Tg, 5.12 Tg, respectively, using the mass of each layer and the carbon content. Total stored carbon in the study area was estimated at 38 Tg, which is equivalent to 0.005% of atmospheric carbon. This suggests that deltas on the globe have accumulated a massive amount of carbon during the evolution. Sediment and carbon were accumulated the most between 2000 and 1000 cal BE Most of the stored carbon before 3000 cal BP accumulated in MM, and after 2000 cal BP in TM.
2012-01-25