Assessment of carbon sequestration and hazardous chemical storage in reed habitats of the Danube Delta Biosphere Reserve’s fluvio-marine sector

The Danube Delta, a dynamic alluvial plain, serves as a substantial carbon sink due to its extensive stands of reeds, specifically Phragmites australis . This study quantifies carbon storage across five distinct reedbed types based on substrate characteristics, using biomass assessment, soil carbon analysis, and GIS-based spatial mapping. Results show that reeds on salinized organic soils (S-Pa) have the highest carbon storage capacity (8.595 t/ha C), while those on gleyic soils (S-F) have the lowest storage levels (0.463 t/ha C). Furthermore, an analysis of heavy metal contamination (Cr, Ni, Pb, Zn) over 5 years revealed concentrations below regulatory thresholds, with a declining trend. The analysis indicates that reeds have notable potential for pollutant sequestration, particularly in aquatic vegetation and soil. These findings highlight the crucial role of deltaic wetland ecosystems in carbon sequestration and contaminant retention, underscoring the need for sustainable management strategies.