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  • 學位論文

表土內氨氧化古菌與細菌的豐富度對於不同溫度下之硝化作用的影響

The Influences of Ammonia Oxidizing Archaeal and Bacterial Abundances on Nitrification Responses to Temperature in Topsoil

指導教授 : 林裕彬

摘要


在全球氮循環中,土壤硝化作用對溫度的反應具有重要意義,然而不同豐富度之氨氮化族群及硝化抑制劑在此過程中所扮演的角色,至今尚未有研究進行探討。本研究採實驗室規模進行,首先經由20種不同的有機或無機肥沃土壤,調查其中氨氧化古細菌(Ammonia oxidizing archaea, AOA)與氨氧化細菌(Ammonia oxidizing bacteria, AOB)之相對豐富度,對於土壤潛在硝化的溫度反應之影響,其次,從不同的土地覆蓋類型蒐集共16種土壤樣本,並藉助馬可夫鏈蒙地卡羅(Markov Chain Monte Carlo)模擬,以SQRT及MMRT模式評估兩種溫度梯度下所測量的土壤潛在硝化之溫度敏感度參數。研究結果顯示,土壤硝化作用對溫度的反應會受到氨氮化族群的相對豐富度與模式參數預估的敏感度所影響,以不同族群豐富度來說,氨氧化古細菌對氨氧化細菌比例高的土壤,亦會有較高的最適溫度,而兩者比例相近的土壤,其硝化作用的溫度差距不大,此情況表示在定溫下所測量的土壤潛在硝化作用,並無法說明氨氧化族群在之中的實際貢獻;以參數敏感度來說,其中兩個熱力參數特別顯著,為中至高之敏感度,且不論何種溫度範圍皆可在模式中單獨識別,此外,控制最小溫度的參數(Tmin)及潛在硝化曲率(〖〖ΔC〗_ 〗_P^‡)分別在SQRT及MMRT模式下僅有微小之敏感度,建議在土壤硝化作用之溫度敏感度模式選擇上應更加謹慎。 硝化抑制劑實驗根據農地或非農地土壤,其資料顯示兩者的硝化抑制劑之抑制效果皆會隨著潛在硝化而減少,且對於最低潛在硝化速率的土壤,需達到抑制效果約50%之硝化抑制劑數量明顯降低,特別是DMPP。然而,硝化抑制劑在溫度梯度下明顯使潛在硝化降低,推測其潛在硝化速率在不同溫度之差異不太可能受到硝化抑制劑之應用所影響。 本研究架構在於提升闡述土壤硝化作用在不同溫度及氨氮化族群豐富度下之準確度,而敏感度分析有助於準確解釋其代表土壤硝化溫度敏感度之既有熱力參數,並提供未來溫度敏感度研究之參考方法。

關鍵字

古細菌 抑制劑 有机 溫度

並列摘要


Soil nitrification responses to temperature have significant implications for the global nitrogen cycle. However, no studies have addressed the role of different relative abundance of ammonia oxidizers and nitrification inhibitors on the temperature response of soil nitrification. Here, laboratory-scale experiments were conducted to firstly investigate the effect of the different relative abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) on the temperature response of soil nitrification potential (NP), imposed on twenty different organic and inorganic fertilized soils. Furthermore, sixteen soil samples were collected from the different land cover types, and NP response was measured across two different temperature gradients to estimate the sensitivity of SQRT and MMRT model-based estimated parameters with the help of Markov Chain Monte Carlo simulation. Our results showed that nitrification response to temperature was influenced by both relative abundances of ammonia oxidizers and sensitivity of models' estimated parameters. Among the different relative abundance of ammonia oxidizers, the soil with high AOA to AOB ratios showed high optimum temperature but narrow temperature ranges for nitrification compared to the soil where AOA to AOB ratio was within the same order of magnitude. These results suggest that measuring soil NP at a fixed temperature does not represent the actual contribution of ammonia oxidizers for nitrification. Regarding parameter sensitivity, we found that two thermodynamic parameters stand out as moderately to highly sensitive and are uniquely identifiable in each model (the parameters a and maximum temperature for SQRT, and the parameters change in enthalpy and change in entropy for MMRT model), regardless of the temperature range. However, parameters that control the minimum temperature and curvature of the NP response curve (Tmin and 〖〖ΔC〗_ 〗_P^‡) were found to have little to no sensitivity to SQRT and MMRT model output, respectively, suggesting a careful selection of complementary models while describing the temperature sensitivity of soil nitrification. Nitrification inhibition experiment showed that the inhibitory effect (IE) of both nitrification inhibitors (NIs) dicyandiamide (DCD) and 3, 4-dimethylpyrazole phosphate (DMPP) decreased with NP. Additionally, the amount of NI required to achieve an IE of approximately 50% was significantly reduced for soils that exhibited the lowest NP rates, especially for DMPP. However, both NIs significantly reduce the NP across the temperature gradient, suggesting that the difference in temperature is less likely to influence the effectiveness of NIs. These results could help to accurately simulate the temperature response of nitrification in a variety of soils. Moreover, this study’s framework provides meaningful ranges for the model’s sensitivity in the simulation of thermodynamically explained soil nitrification kinetics, which may enhance the accurate interpretation of soil biochemical processes and improve fertilized soil management.

並列關鍵字

Archaea Bacteria Inhibitors Nitrogen Organic Temperature

參考文獻


References
1. Ahn, J.-H., Song, J., Kim, B.-Y., Kim, M.-S., Joa, J.-H., Weon, H.-Y., 2012. Characterization of the bacterial and archaeal communities in rice field soils subjected to long-term fertilization practices. J. Microbiol. 50, 754–765.
2. Akiyama, H., Yan, X., Yagi, K., 2010. Evaluation of effectiveness of enhanced‐efficiency fertilizers as mitigation options for N2O and NO emissions from agricultural soils: meta‐analysis. Glob. Chang. Biol. 16, 1837–1846.
3. Alazzy, A.A., Lü, H., Zhu, Y., 2015. Assessing the uncertainty of the Xinanjiang rainfall-runoff model: effect of the likelihood function choice on the GLUE method. J. Hydrol. Eng. 20, 4015016.
4. Alster, C.J., Baas, P., Wallenstein, M.D., Johnson, N.G., von Fischer, J.C., 2016a. Temperature Sensitivity as a Microbial Trait Using Parameters from Macromolecular Rate Theory. Front. Microbiol. 7.

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