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首页> 外文期刊>Soil Biology & Biochemistry >Biology and carbon lability of sub-surface nutrient patches in High Arctic polar deserts drives the probability and magnitude of nitrous oxide emissions
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Biology and carbon lability of sub-surface nutrient patches in High Arctic polar deserts drives the probability and magnitude of nitrous oxide emissions

机译：高北极北极沙漠中亚表面营养贴片的生物学和碳损伤驱动氧化亚氮排放的概率和大小

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摘要

High Arctic polar deserts cover 26% of the Arctic. Climate change is expected to increase cryoturbation in these polar deserts, including frost boils and diapirs. Diapirism-cryoturbic intrusion into the overlying horizon-creates subsurface nutrient patches with low biodegradability and is thought to regulate greenhouse gas emissions, including the potent nitrous oxide. Although nitrous oxide emissions have been observed in polar deserts at a rate comparable to vegetated tundra ecosystems, the underlying mechanism by which nitrous oxide is produced in these environments remains unclear. In this study, we investigated ammonia-oxidizing archaea, which were detected in a previous study, and used stable isotope techniques to characterize the pattern of nitrous oxide emissions from frost boils. Ammonia-oxidizing archaea would be tightly linked to nitrous oxide emissions under aerobic condition whereas low degradable diapiric nutrient would limit denitirification under wet conditions. We hypothesized that (1) diapirism (i.e. diapiric frost boil) would not primarily drive nitrous oxide emissions and therefore abundance of ammonia-oxidizing archaea would be linked to the increase in nitrous oxide emissions under dry conditions favouring nitrification, and (2) diapirism decreases nitrous oxide emissions relative to non-diapiric frost boil under wet conditions that favour denitrification because of the recalcitrant nature of diapiric organic carbon. We used soil samples collected from two High Arctic polar deserts (dolomite and granite) near Alexandra Fjord (78 degrees 51'N, 75 degrees 54'W), Ellesmere Island, Nunavut, Canada from July-august 2013. Ammonia-oxidizing archaea did not differ in abundance between diapiric and non-diapiric frost boils within the dolomitic desert; however, within the granitic desert amoA abundance was 22% higher in diapiric frost boils. In both deserts, the increased abundance of archaeal amoA genes was linked to increased nitrous oxide emissions under dry conditions. Under higher soil moisture conditions favouring denitrification, diapiric frost boils emit N2O with higher probability, but at a lower rate, than non-diapiric frost boils. For example, in the dolomitic desert, diaprism increased the probability of N2O emissions by 104% but decreased the LS mean value of the emission rate by 36%. Similarly, diapirism increased the emission probability by 26% but decreased the LS mean value by 68% within the granitic desert. Under wet conditions, site preference values suggested that fungal and bacterial denitrification were important nitrous oxide emission processes. Our study shows that diapirism is a key cryoturbation process for nitrous oxide emissions in polar deserts primarily through diapirism's alteration of emission probability and the magnitude of the emissions.
机译：高北极极性沙漠占地26％的北极。预计气候变化将增加这些极地沙漠中的冷冻干扰，包括霜冻和催乳乳头。倾泻声侵入覆盖地平线 - 产生具有低生物降解性的地下养分斑块，并被认为调节温室气体排放，包括氧化二氮。尽管在极地沙漠中观察到氧化亚氧化物排放，但是与植被的苔原生态系统相当的速率，但在这些环境中产生氧化二氮氧化物的潜在机制仍不清楚。在这项研究中，我们研究了在先前的研究中检测到的氨氧化archaea，并使用稳定的同位素技术来表征来自霜沸腾的氧化亚氮排放的图案。氨氧化古亚茶将与有氧条件下的氧化亚氮排放紧密相连，而低可降解的浸润营养物将限制在潮湿条件下的二核。我们假设（1）衰落（即酸性霜沸腾）不会推动氧化亚氮排放，因此氨氧化古亚亚氧化的丰富与硝化硝化的干燥条件下的氧化氮排放的增加有关，并且（2）滞质下降在湿润条件下，相对于非酸性霜的氧化氮排放沸腾，因为浸润有机碳的顽固性质是有利于反硝化的。我们在亚历山德拉峡湾（78度51'n，75度54'w）附近，从2013年8月至8月，加拿大南美州努纳岛，伊尔梅梅尔岛，南美州南武岛，采用土壤样本在白云岩沙漠内浸润和非仿生霜之间的丰富性没有差异;然而，在花岗岩中，酸性霜沸腾的花岗岩沙漠氨植物丰度高22％。在两个沙漠中，古氨基基因的增加的丰度与干燥条件下的氧化氮排放量增加。在较高的土壤水分条件下，有利于脱氮，酸性霜沸腾以较高的概率发出N2O，但比非酸性霜沸腾较低。例如，在白云岩沙漠中，依普动动物将N2O排放的概率提高了104％，但降低了降低发射率的平均值36％。同样，滞质增加了26％的发射概率，但在花岗岩沙漠中降低了LS平均值68％。在潮湿的条件下，现场偏好值表明真菌和细菌反硝化是重要的一氧化二氮排放过程。我们的研究表明，休垂体是极性沙漠中一致的氧化亚氮排放的关键呼吸过程，主要是通过诽谤者的排放概率和排放量的幅度。

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