Figure 10.13 Thermokarst lake disturbance and recovery cycle in northeastern Siberian yedoma soils. Soil profile from northeastern Siberia, termed yedoma, with massive Pleistocene-aged ice wedges (upper). Thermokarst-lake expansion (thaw bulb shown in yellow; thaw boundary shown as a dotted line) accompanied by Pleistocene-aged methane (CH4) emissions and release of nitrogen and phosphorus (N+P) from yedoma into lakes, stimulating aquatic productivity and carbon dioxide (CO2) uptake, which offset Pleistocene-aged CO2 emissions from yedoma decay (upper middle). Partially drained lake with atmospheric CO2 uptake by plants forming thick Holocene-aged organic carbon deposits (brown) exceeding CH4 emissions from contemporary organic matter decay (lower middle). Refreezing of remaining Pleistocene and Holocene carbon in sediments following complete lake drainage (new ice wedges are shown as triangles), with peatland-type CH4 emissions and CO2 uptake (lower). The thicknesses of CH4 and CO2 arrows are scaled by relative magnitude on a carbon-mass basis. From Walter Anthony et al. (2014).