Dimension does matter: carbon-based substances with different dimensions exhibit opposite effects on soil CO2 and CH4production.

Currently, carbon-based substances are widely used in agriculture and industry, leading to obvious accumulation in ecosystems. Natural ecosystems, especially water-logged areas, are important sources of greenhouse gases. However, it is not clear whether the dimensions of carbon-based substances can affect their emission. Herein, the effects of three kinds of carbon-based substances (including carbon nanotubes, graphene, and graphite powder) with dimensions from one to three on the CO₂ and CH₄ production potential were tested from a saltmarsh wetland soil. Carbon nanotubes inhibited CH₄ production, and graphene showed slight inhibition. In contrast, graphite powder could promote methanogenesis, and the maximum CH₄ concentration was 53.02 mmol g⁻¹ L⁻¹. With a decrease, the maximum CH₄ concentration with carbon nanotubes was only 38.09 mmol g⁻¹ L⁻¹. Interestingly, the effect of carbon-based substances on CO₂ production was opposite to that on CH₄. Carbon nanotubes showed the greatest promotion effect on CO₂ production. In addition, by comparing the effects of carbon-based substances on global warming equivalent, graphite powder showed a promotion effect compared with the control, while carbon nanotubes decreased it. This study provides basic data for understanding the effects of carbon-based substances with diverse dimensions on greenhouse gas dynamics in saltmarsh wetland soil. [ABSTRACT FROM AUTHOR]