Volatile organic compounds (VOCs) are emitted by plants and microorganisms and have significant impacts on atmospheric chemistry. Soil systems are sources of VOCs driven by abiotic and biotic factors. We investigated the emissions of VOCs by soils and their plant cover from three contrasted biotopes: meadow, heathland and oak forest, during 24-hours in summer. We hypothesized that the spatial and temporal dynamics of VOC fluxes are reflected in soil properties, soil microbial communities, vegetation covers, and litter composition that differed in the three biotopesVOC fluxes were measured after direct on-field sampling at four sampling times (two at night and two at day) using a proton transfer reaction mass spectrometer, and results were linked to some climatic, edaphic and biotic parameters simultaneously monitored in each biotope. While differences in the composition of the soil bacterial communities, in the richness of the plant cover and in some soil physicochemical properties between the three biotopes were observed, the total VOC fluxes from the soil to the atmosphere did not present spatial patterns. However, differences in the mass composition of the VOC spectra were detected; for example, the soil from the forest that was covered with oak leaf litter had specific bacterial communities and emitted distinct VOC spectra than the two other biotopes. The total VOC fluxes responded to rainfall and were significantly driven by soil temperature. While we observed changes in the structure of soil bacterial communities between day and night in all biotopes using fingerprinting analysis, a diurnal dynamic of VOC fluxes was only observed in the forest biotope where the soil was protected from rainfall due to the canopy. This soil presented higher fluxes in day time up to 10.8 µg VOCs h-1 m-2 and lower fluxes in night time down to 3.8 µg VOCs h-1 m-2. Overall, the present study supplies data regarding VOC emissions by soils which are scare compared to plant sources. The results highlighted the complex interconnections existing between abiotic and biotic parameters that could directly or indirectly drive VOC emissions by soil systems.

中文翻译：

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不同生境中土壤系统VOC排放的短期时间动态

挥发性有机化合物 (VOC) 由植物和微生物排放，对大气化学有重大影响。土壤系统是由非生物和生物因素驱动的 VOC 来源。我们在夏季 24 小时内调查了土壤及其植物覆盖物从三个对比生境：草甸、荒地和橡树林中排放的 VOC。我们假设 VOC 通量的时空动态反映在土壤性质、土壤微生物群落、植被覆盖和凋落物组成中，这三种生物群落的 VOC 通量是在四个采样时间（两个在晚上和白天两个）使用质子转移反应质谱仪，结果与在每个生物群落中同时监测的一些气候、土壤和生物参数相关联。虽然观察到土壤细菌群落的组成、植物覆盖的丰富度和三种生物群落之间的一些土壤理化特性的差异，但从土壤到大气的总 VOC 通量没有呈现空间模式。然而，检测到 VOC 光谱的质量组成存在差异；例如，覆盖着橡树叶落叶的森林土壤具有特定的细菌群落，并且发出的 VOC 光谱与其他两种生物群落不同。总 VOC 通量对降雨有反应，并受土壤温度的显着驱动。虽然我们使用指纹分析观察了所有生物群落中土壤细菌群落结构在白天和黑夜之间的变化，仅在森林生物群落中观察到 VOC 通量的昼夜动态，其中土壤因树冠而免受降雨影响。这种土壤在白天的通量较高，最高可达 10.8 µg VOCs h-1 m-2，而在夜间的通量较低，可达 3.8 µg VOCs h-1 m-2。总体而言，本研究提供了有关土壤 VOC 排放的数据，与植物来源相比，这些数据令人恐惧。结果强调了非生物参数和生物参数之间存在的复杂相互关联，这些参数可以直接或间接驱动土壤系统的 VOC 排放。