The multi-annual carbon budget of a peat-covered catchment

Abstract

This study estimates the complete carbon budget of an 11.4 km 2 peat-covered catchment in Northern England. The budget considers both fluvial and gaseous carbon fluxes and includes estimates of particulate organic carbon (POC); dissolved organic carbon (DOC); excess dissolved CO 2; release of methane (CH 4); net ecosystem respiration of CO 2; and uptake of CO 2 by primary productivity. All components except CH 4 were measured directly in the catchment and annual carbon budgets were calculated for the catchment between 1993 and 2005 using both extrapolation and interpolation methods. The study shows that: Over the 13 year study period the total carbon balance varied between a net sink of − 20 to − 91 Mg C/km 2/yr. The biggest component of this budget is the uptake of carbon by primary productivity (− 178 Mg C/km 2/yr) and in most years the second largest component is the loss of DOC from the peat profile (+ 39 Mg C/km 2/yr). Direct exchanges of C with the atmosphere average − 89 Mg C/km 2/yr in the catchment. Extrapolating the general findings of the carbon budget across all UK peatlands results in an approximate carbon balance of − 1.2 Tg C/yr (± 0.4 Pg C/yr) which is larger than previously reported values. Carbon budgets should always be reported with a clear statement of the techniques used and errors involved as this is significant when comparing results across studies.