Amorphous silica pools in permafrost soils of the Central Canadian Arctic and the potential impact of climate change
Amorphous silica pools in permafrost soils of the Central Canadian Arctic and the potential impact of climate change
复制标题
加拿大中部北极永久冻土中的无定形硅库以及气候变化的潜在影响
作者：
Hanna Alfredsson;G. Hugelius;W. Clymans;J. Stadmark;P. Kuhry;D. Conley
我们调查的分布，存储和景观分区土壤无定形二氧化硅（ASi）在加拿大中部地区为主的苔原和泥炭地提供了第一个估计的量存储在北极永久冻土生态系统的ASi。我们假设，类似于土壤有机质，北极土壤储存大量的ASi，这可能会受到预计的气候变化和相关的永久冻土制度的变化。不同土地覆被类型的平均土壤ASi储量（表层1米）在9，600至83，500千克SiO2 ha−1之间。地衣冻原ASi含量最低，而其他土地覆盖类型之间ASi储量无显着差异。明显的差异，观察到分配到顶部有机与矿物层的土壤ASi存储。沼泽泥炭地、沼泽泥炭地和湿润灌木苔原在顶部有机层中储存了7090 - 45,400 kg SiO2 ha−1，而地衣苔原、湿润灌木苔原和干燥灌木苔原的相应储存量仅为1500-1760 kg SiO2 ha−1。硅藻和植硅体是泥炭地和灌丛冻原系统表层有机层ASi储量的重要组成部分，而在灌丛冻原类矿物层ASi储量中，硅藻和植硅体似乎是一个可以忽略的组成部分。ASi浓度随深度下降，在土壤剖面的沼泽泥炭地和所有灌木苔原类，表明循环ASi，而沼泽泥炭地似乎作为汇保留存储ASi千年的时间尺度。我们的研究结果提供了一个概念框架，以评估气候变化对北极陆地硅循环的潜在影响。我们认为，储存在泥炭地的ASi对气候变化特别敏感，因为与灌木苔原系统相比，ASi池的更大部分储存在常年冻土中。气候变暖和冻土融化的一个可能的结果可能是以前冻结的ASi的流动，改变土壤储存的生物来源的ASi和增加的硅通量到北冰洋。
We investigated the distribution, storage and landscape partitioning of soil amorphous silica (ASi) in a central Canadian region dominated by tundra and peatlands to provide a first estimate of the amount of ASi stored in Arctic permafrost ecosystems. We hypothesize that, similar to soil organic matter, Arctic soils store large amounts of ASi which may be affected by projected climate changes and associated changes in permafrost regimes. Average soil ASi storage (top 1 m) ranged between 9600 and 83,500 kg SiO2 ha−1 among different land-cover types. Lichen tundra contained the lowest amounts of ASi while no significant differences were found in ASi storage among other land-cover types. Clear differences were observed between ASi storage allocated into the top organic versus the mineral horizon of soils. Bog peatlands, fen peatlands and wet shrub tundra stored between 7090 and 45,400 kg SiO2 ha−1 in the top organic horizon, while the corresponding storage in lichen tundra, moist shrub- and dry shrub tundra only amounted to 1500–1760 kg SiO2 ha−1. Diatoms and phytoliths are important components of ASi storage in the top organic horizon of peatlands and shrub tundra systems, while it appears to be a negligible component of ASi storage in the mineral horizon of shrub tundra classes. ASi concentrations decrease with depth in the soil profile for fen peatlands and all shrub tundra classes, suggesting recycling of ASi, whereas bog peatlands appeared to act as sinks retaining stored ASi on millennial time scales. Our results provide a conceptual framework to assess the potential effects of climate change impacts on terrestrial Si cycling in the Arctic. We believe that ASi stored in peatlands are particularly sensitive to climate change, because a larger fraction of the ASi pool is stored in perennially frozen ground compared to shrub tundra systems. A likely outcome of climate warming and permafrost thaw could be mobilization of previously frozen ASi, altered soil storage of biogenically derived ASi and an increased Si flux to the Arctic Ocean.