Variations in sediment organic carbon among different types of small natural ponds along Druridge Bay, Northumberland, UK

Small natural ponds from Druridge Bay, Northumberland (UK), were sampled to investigate the variations in sediment organic carbon (OC) content among pond types. Sediment OC was highest in uncompacted sediments from permanent ponds with extensive natural vegetation (means ranged between 7.68 and 12.86% OC) but lower in compacted sediments (mean 3.72% OC) or from ponds in arable or pasture fields (mean 3.44% OC) and from adjacent soil controls (means of 3.13–3.38% OC). The extent of 4 distinct pond types (permanent naturally vegetated, arable field, grass pasture field, and dune slack) varied across years. This study highlights ecological variations among pond types that can result in large variations in sediment OC content and, combined with annual variations to the extent of ponds, poses significant implications for upscaling carbon burial rates based solely on combined surface area.