High rates of carbon burial linked to autochthonous production in artificial ponds

Ponds are globally abundant and important to the global carbon cycle. Although ponds have large greenhouse gas emissions, they also sequester carbon in their sediments. Here, we studied organic carbon (OC) burial rates in 22 temperate experimental ponds with negligible watersheds, where carbon sequestration derives solely from autochthonous primary production. The ponds were built identically in 1964 and have since experienced different management strategies, allowing us to test how management actions influence burial rates. On average, the ponds accumulated 67.1 g OC m⁻² yr⁻¹ (range 38.3–113.6 g OC m⁻² yr⁻¹)—about double the global average burial rate for lakes and similar to global averages for wetlands. Carbon burial rates were higher in ponds with macrophytes, fish, and higher N : P loads. We contend that the global carbon sink for inland waters may be substantially underestimated due to the undervaluation of OC burial in natural and artificial ponds.