生态环境学报 ›› 2022, Vol. 31 ›› Issue (5): 939-948.DOI: 10.16258/j.cnki.1674-5906.2022.05.009

• 研究论文 • 上一篇    下一篇

珠江口红树林土壤甲烷和二氧化碳通量特征及其影响因素研究

张涵1(), 唐常源1,2,3,4,*, 禤映雪2,3,4, 江涛1, 黄品怡1, 杨秋1, 曹英杰2,3,4   

  1. 1.中山大学地理科学与规划学院,广东 广州 510275
    2.中山大学环境科学与工程学院,广东 广州 510275
    3.中山大学/广东省环境污染控制与修复技术重点实验室,广东 广州 510006
    4.南方海洋科学与工程广东省实验室(珠海),广东 珠海 519080
  • 收稿日期:2022-02-10 出版日期:2022-05-18 发布日期:2022-07-12
  • 通讯作者: *
  • 作者简介:张涵(1997年生),女,硕士研究生、研究方向为土壤温室气体排放和碳同位素。E-mail: zhangh589@mail2.sysu.edu.cn
  • 基金资助:
    国家自然科学基金项目(41877470);国家自然科学基金项目(42077154)

The Regular Pattern and Influencing Factors of CO2 and CH4 Fluxes from Mangrove Soil

ZHANG Han1(), TANG Changyuan1,2,3,4,*, XUAN Yingxue2,3,4, JIANG Tao1, HUANG Pinyi1, YANG Qiu1, CAO Yingjie2,3,4   

  1. 1. School of Geography and Planning, Sun Yat-sen University, Guangzhou 510275, P. R. China
    2. School of Enviornmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, P. R. China
    3. Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology/Sun Yat-sen University, Guangzhou 510006, P. R. China
    4. Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519080, P. R. China
  • Received:2022-02-10 Online:2022-05-18 Published:2022-07-12

摘要:

红树林作为碳密度最高的森林生态系统之一,在碳生物地球化学循环过程中发挥着重要作用。该研究以广州市珠江河口红树林土壤为主要研究对象,于2020年8月—2021年7月运用静态箱法分别对红树林中的外滩(靠近海岸)、中滩(植被聚集)和内滩(靠近内陆)的土壤-大气界面的CO2和CH4通量进行观测,探讨红树林生态系统CO2和CH4排放通量的时空分布特征及其对环境因子(温度、含水量以及土壤理化性质)的响应。此外,基于稳定碳同位素(δ13C)特征和Keeling Plot方法综合评估红树林生态系统CO2和CH4通量的来源特征。结果表明,研究期间平均CH4通量为18.97 μmol∙m-2∙h-1,CO2通量均值为4.19 mmol∙m-2∙h-1。CO2和CH4的通量均具有显著的时空差异性,CO2通量最高值出现在3月,CH4在9月达到最高值。CO2通量排序为内滩>中滩>外滩,CH4通量则表现为中滩>外滩>内滩。土壤含水量、pH、EC、ORP和有机碳含量与CO2通量呈负相关关系,CH4通量与土壤含水量、pH和有机碳含量呈正相关关系。虽然研究区红树为C3植物,然而土壤呼吸产生的CO2的同位素特征在内滩为-16.05‰,中滩为-17.73‰,外滩为-29.77‰,内滩和中滩表现为C4植物特征,由此表明藻类成为土壤呼吸来源。内滩的有机质分解程度最高。研究区CH4的分馏系数在外滩、中滩和内滩均小于1.055,CH4产生方式以乙酸产甲烷为主。该研究系统探讨了红树林生态系统CO2和CH4通量、来源及其影响因素,对进一步了解红树林对碳循环及其气候变化的影响具有重要意义。

关键词: 土壤呼吸, 温室气体通量, 二氧化碳(CO2), 甲烷(CH4), 稳定碳同位素

Abstract:

Mangrove, one of the most carbon intensive forest ecosystems, plays an important role in the carbon biogeochemical cycle. The study area located in the Pearl River Estuary. Filed campaign was conducted each month from August 2020 to July 2021. The closed chamber method was used to determine the emission fluxes of CO2 and CH4 from the mangrove soil in the seaward (close to the ocean), middle (vegetation cover) and landward (close to the land) beaches to analyze the spatial and temporal distribution characteristics of CO2 and CH4 emission fluxes and their influencing factors. In addition, the source apportionment of CO2 and CH4 was evaluated based on the stable carbon isotope (δ13C) and Keeling Plot method. The results showed that the mean CH4 and CO2 fluxes during the study period were 18.97 μmol∙m-2∙h-1 and 4.19 mmol∙m-2∙h-1, respectively. Both CO2 and CH4 fluxes showed significant temporal and spatial variations. The maximum value of CO2 and CH4 fluxes was observed in March and September, respectively. The CO2 fluxes were ranked as landward>middle>seaward, and CH4 fluxes were ranked as middle>seaward>landward. Soil moisture, pH, EC, ORP and OC (soil organic carbon content) had negative effects on CO2 fluxes, while CH4 fluxes were positively correlated with soil moisture, pH, and OC. Although mangroves in the study area were C3 plants, the δ13C of CO2 produced by soil respiration was -16.05‰ in the landward, -17.73‰ in the middle, and -29.77‰ in the seaward forest. The landward and middle forests have characteristics of C4 plants, indicating that algae became the source of soil respiration. Fractionation factors of δ13C-CH4 in the seaward, middle and landward forests were less than 1.055, suggesting that acetate fermentation served as a key methanogenic pathway of CH4 emission. This study systematically discussed the fluxes, sources, and influencing factors of CO2 and CH4 in mangroves. It is of great significance to further understand the impact of mangroves on the carbon cycle and climate change.

Key words: soil respiration, greenhouse gases fluxes, carbon dioxide (CO2), methane (CH4), stable carbon dioxide

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