On the origin of carbon dioxide released from rewetted soils.
On the origin of carbon dioxide released from rewetted soils.
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DOI：
10.1016/j.soilbio.2016.06.032
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发表时间：
2016-10
影响因子：
9.7
通讯作者：
Ritz, K.
中科院分区：
文献类型：
--
作者：
Fraser, F. C.;Corstanje, R.;Deeks, L. K.;Harris, J. A.;Pawlett, M.;Todman, L. C.;Whitmore, A. P.;Ritz, K.
当干燥的土壤被再润湿时，总会释放出二氧化碳脉冲，虽然这种现象已经被研究了几十年，但这种二氧化碳的确切来源仍然不清楚。我们假设它可能是化学来源（即通过非生物途径）、生物化学来源（通过游离酶）或生物来源（通过完整细胞）。为了阐明这些途径的相对贡献，对干燥土壤进行了灭菌（双重高压灭菌）或用针对不同模式的抑制剂溶液（15% 三氯乙酸或 1% 硝酸银）进行处理。干燥：再润湿 (DRW) 循环后，土壤中二氧化碳的释放速度非常快，在 6 分钟内达到最大释放速率，96 小时内总流出量的 41% 在前 24 小时内释放。灭菌后二氧化碳流出完全停止，表明再润湿时二氧化碳释放没有非生物（碳酸盐溶解）贡献，并且有明确的证据表明冲水具有有机或生化基础。在抑制剂存在下的再水化表明，在再润湿后的前 24 小时内，生物化学（膜外）和有机体（膜内）来源的贡献大致相等。这表明一些流量来自微生物呼吸，而其余的则是酶活性的结果，可能是通过死细胞碎片中的残余呼吸途径。干燥后再润湿的土壤表现出极快的 CO2 通量，峰值流出发生在不到 6 分钟内。这种二氧化碳通量可以通过高压灭菌来阻止，这表明其来源本质上是生化或有机起源的。强有力的证据表明，细胞外氧化途径促成了这种二氧化碳通量。
When dry soils are rewetted a pulse of CO2 is invariably released, and whilst this phenomenon has been studied for decades, the precise origins of this CO2 remain obscure. We postulate that it could be of chemical (i.e. via abiotic pathways), biochemical (via free enzymes) or biological (via intact cells) origin. To elucidate the relative contributions of the pathways, dry soils were either sterilised (double autoclaving) or treated with solutions of inhibitors (15% trichloroacetic acid or 1% silver nitrate) targeting the different modes. The rapidity of CO2 release from the soils after the drying:rewetting (DRW) cycle was remarkable, with maximal rates of evolution within 6 min, and 41% of the total efflux over 96 h released within the first 24 h. The complete cessation of CO2 eflux following sterilisation showed there was no abiotic (dissolution of carbonates) contribution to the CO2 release on rewetting, and clear evidence for an organismal or biochemical basis to the flush. Rehydration in the presence of inhibitors indicated that there were approximately equal contributions from biochemical (outside membranes) and organismal (inside membranes) sources within the first 24 h after rewetting. This suggests that some of the flux was derived from microbial respiration, whilst the remainder was a consequence of enzyme activity, possibly through remnant respiratory pathways in the debris of dead cells. Soils rewetted after drying exhibit an extremely rapid flux of CO2, peak efflux occurs in less than 6 min. Such CO2 fluxes were prevented by autoclaving, suggesting an intrinsically biochemical or organismal origin to the source. Strong evidence for an extracellular oxidative pathway contributing to such CO2 fluxes was found.
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