Soil organic carbon stabilization by iron in permafrost regions of the Qinghai‐Tibet Plateau

A close relationship exists between soil organic carbon (SOC) and reactive iron; however, little is known about the role of iron in SOC preservation in permafrost regions. We determined the amount of SOC associated with reactive iron phases (OC‐Fe) in the permafrost regions of the Qinghai‐Tibetan Plateau (QTP). The results showed that the percentage of OC‐Fe ranged between 0.9% and 59.5% in the upper 30 cm of soil and that the OC‐Fe represented 19.5 ± 12.3% of the total SOC pool. No clear vertical distribution pattern in OC‐Fe was present in the upper 1 m of soil. Throughout the year, the OC‐Fe accounted for relatively stable proportions of the total SOC pool. This study suggests that approximately 20% of SOC is a potential rusty OC pool in the permafrost regions of the QTP. Biogeochemical processes related to the reaction of iron may play important roles in soil carbon cycles in permafrost regions. Key Points Soil organic carbon associated with reactive iron phases (OC‐Fe) on the Qinghai‐Tibetan Plateau (QTP) was measured The proportions of OC‐Fe showed no clearly vertical or seasonal changes Approximately 20% of soil organic carbon is a potential rusty OC pool in the permafrost regions on the QTP