How do redox and temperature fluctuations influence mineral protection of organic matter during permafrost thaw?

高纬度永久冻土泥炭地锁定了地球上大量的土壤碳。人们非常担心，随着永久冻土融化，这些二氧化碳和甲烷将被释放，进一步加剧全球范围内的气候危机(1)。因此，迫切需要了解在北极迅速变暖的过程中，哪些因素决定了这些地区的碳是否被储存或释放。先前的工作已经证明，碳可以部分地防止活性矿物(如结晶性差的Fe（III)（氧合）氧化物）的降解（3-5）。然而，这些矿物质在缺氧条件下对微生物溶解非常敏感(6)，这表明这种碳汇的稳定性将高度依赖于氧化还原条件和土壤中的微生物群落。由于永久冻土泥炭地是动态环境，其氧化还原条件在一定时间尺度上变化，因此尚不清楚这些活性矿物是否为长期的老碳提供了稳定的汇，或者观察到的铁-碳结合是否由动态条件下周期性捕获在氧化还原界面的“年轻”碳组成。该项目将确定永久冻土泥炭地氧化还原条件的时间变化如何影响铁（III）（氧合）氧化物矿物的稳定性，以及这反过来如何影响永久冻土融化期间有机物的流动性、生物有效性和周转。

High latitude permafrost peatlands lock up vast amounts of Earth's soil carbon. There is much concern that this will be released as CO2 and CH4 following permafrost thaw, further exacerbating the climate crisis on a global scale (1). There is therefore urgent need to understand the factors which dictate whether carbon is stored or released in these regions as the Arctic rapidly warms (2). Previous work has demonstrated that carbon can be, in part, protected from degradation by reactive minerals such as poorly crystalline Fe(III) (oxyhydr)oxides (3-5). However, these minerals are very sensitive to microbial dissolution under anoxic conditions (6), suggesting the stability of this carbon sink will be highly dependent on redox conditions and microbial communities in the soils. Since permafrost peatlands are dynamic environments with redox conditions varying on a range of timescales, it is not yet clear whether with these reactive minerals provide a stable sink for old carbon over for long periods, or if observed Fe-C associations consist of "young" carbon which is periodically trapped at redox interfaces under dynamic conditions. This project will identify how temporal variation in redox conditions in permafrost peatlands impacts the stability of Fe(III) (oxyhydr)oxide minerals and how this, in turn, influences the mobility, bioavailability and turnover of organic matter during permafrost thaw.