Muddying the waters: Impacts of a bogflow on carbon transport and water quality

Landslides of peat have been recorded throughout Britain and Ireland for centuries. Whilst these events are not uncommon, land degradation can amplify their magnitude and frequency and, crucially, their immediate impacts are rarely documented. A 20,000 m3 bogflow event that occurred on land undergoing development in the Irish border area in November 2020 was monitored at high frequency in the major receiving river system (384 km2). Samples collected every seven hours over a 28 day period at a site 37 km downstream were analysed for suspended sediment (SS), particulate organic carbon (POC) and dissolved organic carbon (DOC and UV-derived fractions), synchronous with hydrometeorological data and turbidity. There was no impact of the bogflow on DOC concentrations or loads. However, concentrations of SS and POC in the first samples after the bogflow were 825 mg/L and 346 mg C/L, respectively, and fish kill was estimated at 100 %. Analysis of detrended SS and POC loads suggested the main impacts of the bogflow on water quality lasted just eight days. Over this period, an additional 1318 t of SS and 608 t of POC were transported as far as the monitoring point, equating to 325 % more SS and 925 % more POC than would have been expected otherwise under the same river flow conditions. The carbon loss and water quality impacts were short lived, but nevertheless severe, and highlight the vulnerability of peatlands and the risks when these environments are inappropriately managed.