Ecosystems face new carbon challenge from dissolved organic matter shifts

by Riko Seibo
Tokyo, Japan (SPX) Nov 20, 2025

Global temperature increase is affecting dissolved organic matter, or DOM, found throughout the world's rivers and soils. Recent research led by Kunming University of Science and Technology with collaborators from several countries shows DOM is both a buffer and an accelerator for climate change.

DOM, consisting of molecules released from decaying plants, microorganisms, and plastics, changes in structure as temperatures rise and rainfall patterns shift. These changes directly affect how DOM behaves in the environment.

Lead author Jing Zhao explained, "Our work highlights how global warming can push DOM to act as a carbon source, fueling greenhouse gas emissions, or as a carbon sink, capturing carbon for long periods." These processes are influenced by drought, flooding, wildfires, and permafrost thaw.

Researchers found global warming increases DOM's aromaticity and carboxyl content. Depending on conditions, this produces molecules that either store carbon or release it to the atmosphere. DOM further controls the movement of heavy metals, organic chemicals, and microplastics, sometimes enhancing pollutant binding, in other instances increasing pollutant mobility and risk to ecosystems.

The biological impact of DOM shifts with quantity and structure. While DOM can supply nutrients and offer protection to organisms, excess or chemically altered DOM can heighten reactive oxygen species production or disrupt nutrient intake. Its effect is not always beneficial.

DOM also has feedback effects on climate: increased CO2 and methane emissions from thawing permafrost amplify warming, while long-term carbon storage in peatland DOM works to counter it.

Researchers observed DOM's role extends to regulating pollutants such as mercury, pharmaceuticals, and microplastics. Aromatic DOM formed under drought and warming conditions improves pollutant binding but sometimes carries toxins instead of protecting against them.

Interactions between DOM, pollutants, and organisms increase with climate change. DOM may protect aquatic life from some stressors or, conversely, promote pollutant uptake and oxidative stress. Authors warn against assuming DOM changes are beneficial for ecosystems.

The study advises expanded monitoring of DOM quality, chemical ratios, and redox potential in the environment. Long-term observational networks should be established to track DOM dynamics and support climate mitigation efforts.

Co-author Baoshan Xing said, "Dissolved organic matter is at the intersection of climate, water chemistry, and ecology. Understanding DOM's shifting impact is essential for protecting ecosystems and human well-being in a warming and increasingly complex world."

The authors emphasize interdisciplinary collaboration to advance analytical methods for DOM and better quantify its environmental roles. This work can guide policy choices in climate adaptation, pollution control, and biodiversity protection.

Research Report:The double-edged environmental effect of dissolved organic matter in global climate change