DEGRADATION OF ARCHAEOLOGICAL WOOD UNDER FREEZING AND THAWING CONDITIONS-EFFECTS OF PERMAFROST AND CLIMATE CHANGE

摘要

The degradation of archaeological wood at freezing and thawing temperatures is studied at the site of Qajaa in West Greenland through a combination of environmental monitoring, measurement of oxygen consumption and microscopy of wood samples. Permanently frozen wood is still very well preserved after 2-4000 years, while wood samples that thaw every summer show attack by soft rot and an average density loss of 0.1 g cm~(-3) (corresponding to 25% of the dry mass) over the past 27 years. Future increases in temperature may increase the decay rate significantly (Q_(10) = 4.2 at 0-10°C) but the effects on site depend on local hydrology.