To shake or not to shake: Silicone tube approach for incubation studies on CH4 oxidation in submerged soils.
To shake or not to shake: Silicone tube approach for incubation studies on CH4 oxidation in submerged soils.
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DOI：
10.1016/j.scitotenv.2018.12.090
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
Lichao Fan;M. Shahbaz;T. Ge;Jinshui Wu;Y. Kuzyakov;M. Dorodnikov
中科院分区：
文献类型：
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作者：
Lichao Fan;M. Shahbaz;T. Ge;Jinshui Wu;Y. Kuzyakov;M. Dorodnikov
培养实验是测量不同生态系统和土地利用方式土壤中甲烷氧化潜力的最常用方法。然而，常用的顶空CH 4注入到微观世界和振荡的土壤泥浆在孵育过程中完全消除CH 4（土壤出生）和O2（空气出生）的梯度常见原位，也可能会引起各种错误和干扰。作为一种替代方案，我们建议CH 4输入到微观土壤通过位于泥浆内的硅胶管。我们假设（i）CH 4在泥浆中的扩散不足将通过硅胶管直接将CH 4输送到泥浆中来补偿，因此（ii）可以用土壤硅胶管CH 4注入来取代微观世界的振荡。在29天的淹水水稻土培养期间，最高的CH 4净氧化速率为1.6 μg C g− 1干土h−1，通过硅胶管将13 CH 4注入浆液中后第3 - 7天测量，无需振摇。该速率比顶空进样后未振摇的相应CH 4氧化快1.5-2.5倍（支持第一假设）。正如预期的那样，与顶空进样相比，无论进样方法如何，振摇加速CH 4氧化3.2-3.7倍（在第3-7天最强烈）。尽管如此，硅胶管注射不振摇和顶空注射振摇之间的速率相似。这支持了硅胶管替代常见振摇方法的假设潜力（第2种假设）。此外，振荡处理使CH 4中13 C掺入土壤有机质和微生物生物量的能力比直接注入和静态对照提高了1.8-2.7倍。这反映了由于摇动而对CH 4氧化的高估。我们的结论是，通过硅胶管直接土壤CH 4注入是有利的，因为气体浓度梯度保持在孵化实验，从而更真实地反映自然土壤条件。
Incubation experiments are the most common approach to measure methane (CH4) oxidation potential in soils from various ecosystems and land-use practices. However, the commonly used headspace CH4injection into microcosms and the shaking of the soil slurry during incubation fully removes CH4(soil-born) and O2(air-born) gradients common in situ, and may also induce various errors and disturbances. As an alternative, we propose CH4input into microcosm soils via a silicone tube located within the slurry. We hypothesized that (i) poor CH4diffusion in slurry will be compensated by direct CH4delivery into the slurry via a silicone tube and, consequently, (ii) shaking of microcosms can be substituted with the soil silicone tube CH4injection.During a 29-day submerged paddy soil incubation, the highest net CH4oxidation rate was 1.6 μg C g−1dry soil h−1, measured between the 3rd and 7th day after injecting13CH4into the slurry via a silicone tube without shaking. This rate was 1.5–2.5 times faster than the respective CH4oxidation after headspace injection without shaking (1st hypothesis supported). As expected, shaking accelerated CH4oxidation regardless of injection methods by 3.2–3.7 times (most intensively on days 3–7) compared to headspace injection without shaking. Nonetheless, the rates were similar between silicone tube injection without shaking and headspace injection with shaking. This supports the hypothesized potential of silicone tubes to substitute the common shaking method (2nd hypothesis). Furthermore, shaking increased the incorporation of13C from CH4into soil organic matter and microbial biomass by 1.8–2.7 times compared with CH4injection into tubes and the static control without tubes. This reflects an overestimation of CH4oxidation due to shaking. We conclude that direct soil CH4injection via silicone tubes is advantageous in incubation experiments because gas concentration gradients are maintained and thereby more realistically reflect natural soil conditions.