生态环境学报 ›› 2023, Vol. 32 ›› Issue (4): 733-743.DOI: 10.16258/j.cnki.1674-5906.2023.04.011

• 研究论文 • 上一篇    下一篇

长江口水体化能自养固碳过程的潮周期变化特征及影响因素

王馨雨1(), 高灯州1, 刘博林1, 王斌1, 郑艳玲2,3, 李小飞1, 侯立军1,*()   

  1. 1.华东师范大学/河口海岸学国家重点实验室，上海 200241
    2.华东师范大学/地理信息科学教育部重点实验室，上海 200241
    3.华东师范大学地理科学学院，上海 200241
  • 收稿日期:2023-01-14 出版日期:2023-04-18 发布日期:2023-07-12
  • 通讯作者: *侯立军（1975年生），男，教授，研究方向为河口海岸生源要素循环。E-mail: ljhou@sklec.ecnu.edu.cn
  • 作者简介:王馨雨（1997年生），女，硕士研究生，研究方向为河口海岸生源要素循环。E-mail: w_wwxy@163.com
  • 基金资助:
    国家自然科学基金项目(42030411);国家自然科学基金项目(41725002);国家自然科学基金项目(41971105);国家自然科学基金项目(41671463);国家自然科学基金项目(41730646)

The Tidal-cycle Variation and Influencing Factors of Dark Carbon Fixation Process in the Yangtze Estuary

WANG Xinyu1(), GAO Dengzhou1, LIU Bolin1, WANG Bin1, ZHENG Yanling2,3, LI Xiaofei1, HOU Lijun1,*()   

  1. 1. State Key Laboratory of Estuarine and Coastal Research/East China Normal University, Shanghai 200241, P. R. China
    2. Key Laboratory of Geographic Information Science (Ministry of Education)/East China Normal University, Shanghai 200241, China
    3. School of Geographic Sciences, East China Normal University, Shanghai 200241, China
  • Received:2023-01-14 Online:2023-04-18 Published:2023-07-12

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摘要：

河口水体中硝化微生物的化能自养固碳（DCF）对碳氮循环过程有着重要影响，但目前关于河口水体氨氧化微生物对DCF过程的贡献鲜见报道。以长江口为研究区，利用14C和15N同位素示踪技术，分别测定了大潮和小潮期间水体DCF和硝化速率，并通过实时荧光定量PCR技术量化了相关功能基因丰度。结果表明，长江口水体大小潮期间，DCF和硝化速率分别介于170.72－1007.35 nmol?L?1?d?1和1.45－70.75 nmol?L?1?h?1，呈现大潮速率相对较高，小潮速率低的变化特征，且底层水体DCF和硝化速率显著高于表层水体。水体中铵盐和可溶性无机碳浓度是影响DCF和硝化速率的关键环境因子。定量PCR结果表明，大潮和小潮时cbbL基因丰度分别为0.40×108－3.40×108 copies?L?1和0.49×108－2.27×108 copies?L?1，均高于cbbM基因丰度（大潮：0.67×108－9.84×106 copies?L?1，小潮：0.75×108－5.73×106 copies?L?1）。小潮时水体accA基因丰度（0.16×108－2.65×108 copies?L?1）高于大潮时（0.20×108－3.92×108 copies?L?1），并且底层均高于表层。在整个潮周期中，自养固碳功能基因丰度总体呈现涨潮时增加，落潮时降低的变化趋势。氨氧化古菌（AOA）和氨氧化细菌（AOB）是DCF过程的主要贡献者，AOA amoA和AOB amoA丰度在大潮和小潮之间存在显著差异，大潮时AOA amoA基因丰度（0.22×107－3.59×107 copies?L?1）明显高于AOB amoA基因丰度（0.26×107－1.61×107 copies?L?1），而小潮时AOB amoA丰度占据优势，为0.92×106－1.32×106 copies?L?1，表明潮汐过程可通过改变水体化能自养微生物群落组成来影响DCF。该研究深化了长江口潮周期水体DCF和硝化过程速率变化特征的认识，揭示了河口水体硝化微生物驱动的DCF过程的重要性，以期为全球变化背景下河口生态系统碳汇功能评估提供一定的科学参考。

关键词: 化能自养微生物, 长江口, 硝化速率, 固碳速率, 丰度

Abstract:

Dark carbon fixation (DCF) driven by nitrifying microorganisms has an important influence on carbon and nitrogen cycling in estuarine waters, but the contribution of ammonia-oxidizing microorganisms to the DCF process in estuarine waters remains unclear. In this study, DCF and nitrification rates in the water column during spring and neap tides were measured using 14C and 15N isotope tracing techniques, respectively, and related functional gene abundance was quantified by real-time quantitative PCR. The results showed that DCF and nitrification rates in the Yangtze Estuary were in the range of 170.72-1007.35 nmol?L?1?d?1 and 1.45-70.75 nmol?L?1?h?1 during spring and neap tides, respectively, suggesting that these two process rates were higher at spring tides. DCF and nitrification rates in the bottom water were significantly higher than those in the surface water. Ammonium and dissolved inorganic carbon concentrations in the water column were the key environmental factors affecting DCF and nitrification rates. Quantitative PCR results showed that the abundance of cbbL copies was in the range of 0.40×108-3.40×108 copies?L?1 in spring tides and 0.49×108-2.27×108 copies?L?1 in neap tides, which were higher than cbbM copies (spring tides: 0.67×106-9.84×106 copies?L?1, neap tides: 0.75×106-5.73×106 copies?L?1). The abundance of accA genes in neap tides (0.16×108-2.65×108 copies?L-1) was higher than that in spring tides (0.20×108-3.92×108 copies?L?1), and it was also greater in the bottom water than in the surface water. In the whole tidal cycle, the abundance of autotrophic carbon sequestration genes increased at high tide and decreased at low tide. Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were the main contributors to the DCF process, and AOA amoA and AOB amoA gene abundance varied significantly between spring and neap tides, with AOA amoA gene abundance (0.22×107-3.59×107 copies?L?1) being higher than AOB amoA gene abundance (0.26×107?1.61×107 copies?L?1) at spring tides and AOB amoA gene abundance (0.92×106-1.32×106 copies?L?1) dominating at neap tides. These results suggest that tidal processes can affect DCF by altering the composition of chemoautotrophic microbial community in the water column. Overall, this study deepens the understanding of the variation characteristics of the DCF and nitrification rates in the Yangtze Estuary, reveals the importance of the DCF process driven by nitrifying microorganisms in estuarine waters and has important significance for assessing the carbon sink function of estuarine ecosystems.

Key words: chemoautotrophic microorganism, nitrification rate, dark carbon rate, abundance, environmental factors

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