SCBG proposes a whole-system method for tracing wetland organic carbon sources

South China Botanical Garden, Chinese Academy of Sciences has filed a patent application titled “A whole-system method for tracing organic carbon sources in wetlands.” The method addresses the complex origins of organic carbon in saltmarshes and other wetland ecosystems, where conventional tracing approaches often provide only broad source separation. It establishes an integrated workflow from sediment sampling and biomarker measurement to quantitative source apportionment.

Coastal wetlands, especially saltmarshes, are shaped by the combined influence of terrestrial inputs, riverine transport, tides, and marine processes. Their sedimentary organic carbon includes both autochthonous carbon produced within the wetland and allochthonous carbon derived from adjacent terrestrial and marine systems. Existing approaches based on stable isotopes and N/C ratios are useful for broad discrimination among terrestrial, marine, and plant-derived carbon, but they provide limited resolution for identifying more detailed plant and microbial sources.

The proposed method integrates two classes of biomarkers: n-alkanes and amino sugars. N-alkanes help identify plant-derived organic matter from different source groups, while amino sugars indicate microbial necromass carbon. Based on these biomarkers and total organic carbon measurements, the method enables quantitative comparison of six biological carbon sources: herbaceous plants, woody plants, aquatic plants, algae, fungal necromass carbon, and bacterial necromass carbon.

In practice, n-alkane concentrations can be determined by gas chromatography-mass spectrometry, while amino sugars can be measured by high-performance liquid chromatography. The patent document demonstrates the workflow using sediment samples from the Yellow River Estuary and Yancheng saltmarshes, with stable isotope and endmember mixing model results used for validation. This provides a methodological basis for resolving complex multi-source carbon inputs in wetland sediments.

The method may support research on wetland carbon cycling, blue carbon accounting, the monitoring of algal carbon inputs, and the evaluation of wetland conservation and restoration outcomes. Beyond saltmarshes, it has potential applicability to mangroves, lakes, marshes, forests, grasslands, and other ecosystems where source-resolved organic carbon analysis is needed.

The patent application was filed by South China Botanical Garden, Chinese Academy of Sciences, with inventors including WANG Faming, ZHOU Jinge, GAN Shuchai, LU Zhe, QIN Guoming, ZHANG Jingfan, LI Yingwen, and LI Yongxing.

（Image by LIU WANG Faming）