The current assessments of the carbon turnover in the Arctic tundra are subject to large uncertainties. One of the reasons is the general shortage of flux data from the vast and sparsely inhabited Arctic region. Addressing this issue, fluxes of carbon dioxide and methane have been determined on an active flood plain in the Siberian Lena River Delta during the growing seasons 2014 and 2015 by means of the eddy covariance method. For explaining the pronounced spatiotemporal variability in the carbon fluxes, a set of environmental parameters has been utilised. This data set may help to refine estimates of the pan-Arctic greenhouse gas budget and the reduction of its uncertainties.