| XU Xinwanghao,FU Guanghe,ZOU Xinqing,GE Chendong,ZHAO Yifei. 2017. Diurnal variations of carbon dioxide, methane, and nitrous oxide fluxes from invasive Spartina alterniflora dominated coastal wetland in northern Jiangsu Province. Acta Oceanologica Sinica, 36(4):105－113 |
| Diurnal variations of carbon dioxide, methane, and nitrous oxide fluxes from invasive Spartina alterniflora dominated coastal wetland in northern Jiangsu Province |
| 苏北滨海湿地互花米草潮滩CO2,CH4和N2O通量的日变化规律 |
| Received:December 19, 2015 Revised:May 01, 2016 |
| DOI：10.1007/s13131-017-1015-1 |
| Key words:methane nitrous oxide carbon dioxide diurnal variation S. alterniflora |
| 中文关键词: CH4 N2O CO2 日变化 互花米草 |
| 基金项目: |
| Author Name | Affiliation | E-mail | | XU Xinwanghao | Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China | | | FU Guanghe | Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China | fgh@nju.edu.cn | | ZOU Xinqing | Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China | | | GE Chendong | Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China | | | ZHAO Yifei | Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China | |
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| Abstract: |
| The invasions of the alien species such as Spartina alterniflora along the northern Jiangsu coastlines have posed a threat to biodiversity and the ecosystem function. Yet, limited attention has been given to their potential influence on greenhouse gas (GHG) emissions, including the diurnal variations of GHG fluxes that are fundamental in estimating the carbon and nitrogen budget. In this study, we examined the diurnal variation in fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from a S. alterniflora intertidal flat in June, October, and December of 2013 and April of 2014 representing the summer, autumn, winter, and spring seasons, respectively. We found that the average CH4 fluxes on the diurnal scale were positive during the growing season while negative otherwise. The tidal flat of S. alterniflora acted as a source of CH4 in summer (June) and a combination of source and sink in other seasons. We observed higher diurnal variations in the CO2 and N2O fluxes during the growing season (1 536.5 mg CO2 m-2 h-1 and 25.6 μg N2O m-2 h-1) compared with those measured in the non-growing season (379.1 mg CO2 m-2 h-1 and 16.5 μg N2O m-2 h-1). The mean fluxes of CH4 were higher at night than that in the daytime during all the seasons but October. The diurnal variation in the fluxes of CO2 in June and N2O in December fluctuated more than that in October and April. However, two peak curves in October and April were observed for the diurnal changes in CO2 and N2O fluxes (prominent peaks were found in the morning of October and in the afternoon of April, respectively). The highest diurnal variation in the N2O fluxes took place at 15:00 (86.4 μg N2O m-2 h-1) in June with an unimodal distribution. Water logging in October increased the emission of CO2 (especially at nighttime), yet decreased N2O and CH4 emissions to a different degree on the daily scale because of the restrained diffusion rates of the gases. The seasonal and diurnal variations of CH4 and CO2 fluxes did not correlate to the air and soil temperatures, whereas the seasonal and diurnal variation of the fluxes of N2O in June exhibited a significant correlation with air temperature. When N2O and CH4 fluxes were converted to CO2-e equivalents, the emissions of N2O had a remarkable potential to impact the global warming. The mean daily flux (MF) and total daily flux (TDF) were higher in the growing season, nevertheless, the MF and TDF of CO2 were higher in October and those of CH4 and N2O were higher in June. In spite of the difference in the optimal sampling times throughout the observation period, our results obtained have implications for sampling and scaling strategies in estimating the GHG fluxes in coastal saline wetlands. |
| 中文摘要: |
| 外来种互花米草的引入，对苏北滨海湿地生态系统的功能以及生物多样性造成一定的影响，尤其是温室气体的排放方面。然而，有关互花米草对滨海湿地温室气体排放的研究却相对缺乏，特别是小尺度范围内，比如温室气体排放的日变化规律方面。基于此，本研究选择2013年的6月，10月，12月以及2014年的4月，分别代表夏季、秋季、冬季和春季，在每个季节中选取一个整天，利用静态暗箱-气相色谱法对CO2，CH4和N2O通量的日变化进行观测以及分析。结果发现：（1）CH4平均通量在互花米草的生长季表现为排放，而在非生长季表现为吸收；在夏季，基本上表现为CH4的排放，而在其他季节，则既有排放，也有吸收。CO2和N2O平均通量则表现为生长季明显大于非生长季，其中生长季平均CO2通量是1536.5 mg CO2 m-2 h-1，非生长季则是379.1 mg CO2 m-2 h-1，而N2O分别是25.6和16.5 μg N2O m-2 h-1。（2）在日变化尺度范围内，除了10月份，在其他月份，日平均CH4通量均大于夜平均CH4通量；6月份CO2通量和10月份的N2O通量的日变化则主要呈现出一些波动趋势，而10月份和4月份的CO2和N2O通量则成双峰分布，在10月份，主峰出现在早上，而在4月份，主峰则出现在下午。6月份的N2O通量的日变化呈单峰分布，峰值出现在15：00（86.4 μg N2O m-2 h-1）。（3）10月份，互花米草潮滩由于降水原因出现一定程度的积水，积水增加了CO2的排放，却降低了N2O和CH4的排放。（4）昼夜平均以及总CO2通量在10月份大于其他月份，而CH4和N2O则在6月份最大。（5）温室气体通量存在着一定的日变化，所以选择最优化的采样时间对于大时间尺度内（季节和年际）碳排放结果的估算有重要的影响，本文的研究结果可以为滨海湿地温室气体通量的日变化取样的最优时间段的选取提供一定的建议。 |
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