Reviews and syntheses: Contribution of sulfate to methane oxidation in upland soils: a mini-review

Abstract. Methane (CH₄) is a potent greenhouse gas, its global warming potential is 25 times higher than carbon dioxide (CO₂), and various environmental factors influence CH₄ oxidation in soil. Sulfate (SO₄^2-) ion is the main component of atmospheric deposition and has been increasing in recent years, it promotes CH₄ production and anaerobic CH₄ oxidation, however, the impact of SO₄^2- on CH₄ oxidation remains inconclusive. Due to the limited research on the effects of SO₄^2- on CH₄ oxidation, we synthesize current research on the effects of SO₄^2- on CH₄ oxidation, examining both its direct impact and its influence on the dynamics of soil substances, and the potential indirect effects of SO₄^2- on CH₄ oxidation. Through a literature review, we identified that SO₄^2- facilitates CH₄ oxidation within a range of 3–42 %, moreover, it has been found that various physicochemical properties and processes in the soil are influenced by the addition of SO₄^2-, which in turn affects CH₄ oxidation. This review enhances our understanding of the role of SO₄^2- in promoting CH₄ oxidation and lays the foundation for future studies aimed at validating these findings by quantifying CH₄ flux and oxidation rates, as well as elucidating the underlying microbial processes via experimental research. This review deepens the comprehension of atmospheric CH₄ flux and the global CH₄ cycle, particularly in the context of potential global environmental changes.