Organic carbon pathways from the Cuvette Centrale peatlands to the Congo River network

The storage of organic carbon on land and its transfer to the ocean via rivers plays a critical role in the global carbon cycle. As the second-largest river system on Earth, the Congo Basin is a key region for carbon storage and export, with extensive wetlands and tropical forests contributing to a significant aboveground organic carbon reservoir. Recent discoveries have identified the Cuvette Centrale, a low-gradient depression in the center of the Congo Basin, as the world’s largest tropical peat complex, storing approximately 29 petagrams of carbon belowground. Despite its importance, key processes governing the export of carbon from these peatlands to the Congo River network remain poorly understood. Previous studies have shown that despite its low sediment load, the Congo River has a high dissolved organic carbon (DOC) and particulate organic carbon (POC) export—around 2 Tg POC and 12.5 Tg DOC annually. Aged organic matter observed in offshore marine sediment cores suggests, peatlands may significantly contribute to carbon export, but direct evidence remains incomplete. Here, we present a data set comprising surface peat and soil, as well as water, suspended sediment, and river bank samples. These were collected from the surface and small water bodies (pools) in the peatlands, tributaries within and outside the Cuvette Centrale, and the Congo River mainstem. We measured stable carbon and hydrogen isotopes of plant waxes and bulk organic carbon and nitrogen concentrations and stable isotopes, as well as radiocarbon content on a subset of samples. Based on these data, we aim to investigate the significance and the pathways of carbon export from these peatlands and their respective contributions to riverine DOC and POC, alongside other sources such as standing vegetation and in-situ aquatic production. This study provides new insights into the role of the Cuvette Centrale peatlands in the Congo Basin’s carbon dynamics.