Carbon retention in wetlands under different anthropogenic pressures: effects of reed mowing and pollution in the Burgas lake Ramsar site

Wetlands are acknowledged as important resources for carbon storage, yet their capacity to facilitate longterm carbon storage is extremely susceptible to human influence. Here, we evaluate the impacts of various management regimes on carbon retention at the Burgas lake RAMSAR site, Bulgaria - a wetland of international importance that also supports rich biodiversity. We conducted field soil analyses and satellite observations to assess unmanaged, occasionally mown, regularly managed and polluted wetland areas. Soil samples collected in July 2025, revealed clear contrasts: the unmanaged site contained the highest carbon and nitrogen levels, while mown and polluted sites showed reduced carbon retention and altered nutrient balances. Electrical conductivity was significantly elevated in the polluted zone, reflecting anthropogenic pressure. Remote sensing indicators, derived from Sentinel-2 (NDVI, NDRE, MSAI2, NBR, NDWI), showed vegetation productivity, chlorophyll content, soil background effects, moisture and structural disturbance. High positive correlations were noted as a result for the soil carbon, as an index with the vegetation indices and negative correlations with pH and moisture proxies. These results reveal how management and disturbance determine the carbon dynamics in wetlands, and show the benefit of combination of soil and remote sensing methods. The findings are the basis to guide research and implement evidence-based solutions for restoring and managing wetlands, and promoting the carbon sequestration ability of wetlands, without jeopardizing ecological soundness.