The hyperarid soils of the Atacama Desert, Chile, contain the largest known nitrate deposits in the world. They also represent one of the most hostile environments for microbial life anywhere in the terrestrial biosphere. Despite known for its extreme dryness, several heavy rainfall events causing localised flash flooding have struck Atacama Desert core regions during the last five years. It remains unclear, however, whether these soils can support microbial denitrification. To answer this, we sampled soils along a hyperaridity gradient in the Atacama Desert and conducted incubation experiments using a robotized continuous flow system under a He/O₂ atmosphere. The impacts of four successive extreme weather events on soil-borne N₂O and N₂ emissions were investigated, i) water addition, ii) NO₃⁻ addition, iii) labile carbon (C) addition, and iv) oxygen depletion. The ¹⁵N–N₂O site-preference (SP) approach was further used to examine the source of N₂O produced. Extremely low N₂O fluxes were detected shortly after water and NO₃⁻ addition, whereas pronounced N₂O and N₂ emissions were recorded after labile-C (glucose) amendment in all soils. Under anoxia, N₂ emissions increased drastically while N₂O emissions decreased concomitantly, indicating the potential for complete denitrification at all sites. Although increasing aridity significantly reduced soil bacterial richness, microbial potential for denitrification and associated gene abundance (i.e., napA, narG, nirS, nirK, cnorB, qnorB and nosZ) was not affected. The N₂O¹⁵N site preference values based on two end-member model suggested that fungal and bacterial denitrification co-contributed to N₂O production in less arid sites, whereas bacterial denitrification dominated with increasing aridity. We conclude that soil denitrification functionality is preserved even with lowered microbial richness in the extreme hyperarid Atacama Desert. Future changes in land-use or extreme climate events therefore have a potential to destabilize the immense reserves of nitrate and induce significant N₂O losses in the region.

智利阿塔卡马沙漠的高干旱土壤含有世界上已知最大的硝酸盐矿床。它们还代表了陆地生物圈中任何地方对微生物生命而言最不利的环境之一。尽管以极端干旱着称，但在过去五年中，几次暴雨事件导致局部山洪泛滥，袭击了阿塔卡马沙漠的核心地区。但是，这些土壤是否可以支持微生物反硝化还不清楚。为了回答这个问题，我们在阿塔卡马沙漠沿高干旱梯度对土壤取样，并在He / O ₂气氛下使用机器人连续流系统进行了孵育实验。连续四次极端天气事件对土壤中N ₂ O和N _2的影响排放进行了调查，i）水此外，II）NO ₃ ^-另外，ⅲ）有效碳（C）另外，和iv）氧气耗尽。的¹⁵ N-N ₂ ö网站偏好（SP）的方法，进一步用于检查n的源₂ O产生。极低Ñ _2个检测ö通量水后不久和NO ₃ ^-此外，虽然明显Ñ ₂ O和N _2吨的排放量后不稳定-C（葡萄糖）在所有土壤修正案记录。在缺氧条件下，N ₂排放急剧增加，而N ₂随之而来的是O排放量的减少，这表明在所有地点都有完全脱氮的潜力。尽管增加的干旱显着降低了土壤细菌的丰富度，但反硝化作用的微生物潜力和相关的基因丰度（即napA，narG，nirS，nirK，cnorB，qnorB和nosZ）并未受到影响。基于两个末端成员模型的N ₂ O ¹⁵ N位点偏好值表明，真菌和细菌的反硝化作用共同促成N ₂在较少干旱的地方生产O，而细菌的反硝化作用则以增加的干旱为主导。我们得出结论，即使极端极端干旱的阿塔卡马沙漠中微生物含量降低，土壤反硝化功能仍然得以保留。因此，土地利用或极端气候事件的未来变化可能破坏该地区大量硝酸盐的稳定，并导致该地区大量N ₂ O损失。