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Purpose <p>The migration and transformation of nitrogen are key processes for maintaining ecosystem balance. In high-water-table mining regions of eastern China, underground mining has induced large-scale subsidence water bodies, the soil of farmland turned into new aquatic sediments. This conversion between water and soil resource would significantly affect nitrogen cycling processes, the mechanisms of nitrogen removal in sediments is critical to reveal the nitrogen recycle in coal mining subsidence area.</p> Methods <p>We selected typical coal mining subsidence waters of eastern China as the research region, discussed the correlation between nitrogen removal rate and multiple factors such as sediment properties, functional genes, and microbial communities. The <sup>15</sup>N isotope tracing was used to analyze the nitrogen removal rate, while qPCR and <i>16&#xa0;S rRNA</i> were used to systematically analyze the seasonal changes of functional gene abundance and microbial community structure.</p> Results <p>(1) Denitrification was the primary pathway of nitrogen removal, with rates ranging from 1.46 to 8.17 nmol g⁻¹ h⁻¹, contributing 83–94% of the total nitrogen removal, and exhibiting a “high in summer, low in winter” seasonal trend. Anammox rate ranged from 0.243 to 0.676 nmol g⁻¹ h⁻¹. (2) The abundances of the <i>nirS</i> and <i>nosZ</i> genes were significantly correlated with denitrification rates (<i>p</i> &lt; 0.05), and the abundance of the <i>AMX</i> gene was significantly positively correlated with the anammox rate (<i>p</i> &lt; 0.001). (3) Dominant denitrifying bacterial genera were <i>Mesorhizobium</i>, <i>Rhizobium</i>, and <i>Bradyrhizobium</i>, while <i>Candidatus Brocadia</i> was the predominant anammox bacterium. (4) pH, NO₃⁻-N, and TOM were the key environmental factors influencing nitrogen removal rate, and the nitrogen removal process in the sediment was regulated by environmental factors and relied primarily on dominant functional gene groups rather than microbial diversity.</p> Conclusion <p>This study enhances the understanding of nitrogen cycling in mining-impacted aquatic systems and provides a theoretical basis for nitrogen pollution control and ecological restoration in mining regions.</p>

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Nitrogen removal rate and microbial influence mechanism of the sediment in coal mining subsidence water area

  • 期刊论文

  • 发表日期：

    2026年5月9日

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  • Sun Xueliang,
  • Wang Shun,
  • Fan Tingyu,
  • Yu Xiaokun,
  • Wang Xingming,
  • Lu Akang,
  • Zhang Xinghui,
  • Yang Changde

摘要

Purpose

The migration and transformation of nitrogen are key processes for maintaining ecosystem balance. In high-water-table mining regions of eastern China, underground mining has induced large-scale subsidence water bodies, the soil of farmland turned into new aquatic sediments. This conversion between water and soil resource would significantly affect nitrogen cycling processes, the mechanisms of nitrogen removal in sediments is critical to reveal the nitrogen recycle in coal mining subsidence area.

Methods

We selected typical coal mining subsidence waters of eastern China as the research region, discussed the correlation between nitrogen removal rate and multiple factors such as sediment properties, functional genes, and microbial communities. The 15N isotope tracing was used to analyze the nitrogen removal rate, while qPCR and 16 S rRNA were used to systematically analyze the seasonal changes of functional gene abundance and microbial community structure.

Results

(1) Denitrification was the primary pathway of nitrogen removal, with rates ranging from 1.46 to 8.17 nmol g⁻¹ h⁻¹, contributing 83–94% of the total nitrogen removal, and exhibiting a “high in summer, low in winter” seasonal trend. Anammox rate ranged from 0.243 to 0.676 nmol g⁻¹ h⁻¹. (2) The abundances of the nirS and nosZ genes were significantly correlated with denitrification rates (p < 0.05), and the abundance of the AMX gene was significantly positively correlated with the anammox rate (p < 0.001). (3) Dominant denitrifying bacterial genera were Mesorhizobium, Rhizobium, and Bradyrhizobium, while Candidatus Brocadia was the predominant anammox bacterium. (4) pH, NO₃⁻-N, and TOM were the key environmental factors influencing nitrogen removal rate, and the nitrogen removal process in the sediment was regulated by environmental factors and relied primarily on dominant functional gene groups rather than microbial diversity.

Conclusion

This study enhances the understanding of nitrogen cycling in mining-impacted aquatic systems and provides a theoretical basis for nitrogen pollution control and ecological restoration in mining regions.