CASE STUDY ON GREENHOUSE GAS (GHG) FLUXES FROM FLOODED FORMER PEAT EXTRACTION FIELDS IN CENTRAL PART OF LATVIA

Abstract

Flooded Land is defined as water bodies where human activities have caused changes in the amount of surface area covered by water, typically through water level regulation. Former peat extraction fields are a type of flooded lands which are often mentioned as significant source of greenhouse gas (GHG) emissions. In Latvia, the area of flooded lands in former peat extraction fields is 5.3 kha. The aim of the study is to evaluate GHG emissions from flooded former peat extraction fields to define that the flooded lands are the key source of GHG emissions and approve that further studies are necessary to elaborate country specific emission factors. The study is implemented in three areas in central part of the country, where peat extraction was stopped 25-35 years ago. Measures continued for 12 months, in 9 subplots, each was represented by 3 measurement points. Water and air temperature, as well as water level was measured during the study. According to the study results, flooded areas are a significant source of CO2 emissions (967±107 kg CO2-C ha-1 yr-1); however, the most significant agent of GHG emissions in flooded areas is methane (CH4 ) – 435±98 kg CH4-C kg ha-1 yr-1. Flooded areas are not significant source of nitrous oxide (N2 O) emissions. The net emissions from flooded areas are 18.1±3.7 tons CO2 eq ha-1 yr-1. According to the study results, flooded lands are a significant (one of the largest) source of emissions, and further studies are necessary to improve GHG modelling solutions and activity data.