Carbon burial rates increased with pond age Areal and annual C burial rates were calculated for four to six sediment cores extracted per pond in June 2019 using total OC (TOC), dry weight, and piston corer dimensions. Mean TOC content in whole cores of ponds ranged from 1.7 to 26.5{6d6906d986cb38e604952ede6d65f3d49470e23f1a526661621333fa74363c48} (Table 1 and Supplementary Fig. 1). The areal OC stock ranged from 306 ± 8.2 g OC m−2 in Pond 14 (14-year-old pond) to 7380 ± 56.1 g OC m−2 in Pond 34 (34-year-old pond), increasing linearly with increasing pond age (R2 = 0.99, p < 0.001, Fig. 1a and Table 1). Scaling this OC stock by pond age (assuming constant burial rates over time) yields estimated annual burial rates ranging from 21.8 ± 7.5 g OC m−2 y−1 in Pond 14 to 217 ± 50.2 g OC m−2 y−1…