In-situ measurement of greenhouse gas emissions from a coastal estuarine wetland using a novel continuous monitoring technology: Comparison of indigenous and exotic plant species

Besides water table depth, soil temperature is one of the main drivers of greenhouse gas (GHG) emissions in intact and managed peatlands. In this work, we evaluate the performance of remotely sensed land surface temperature (LST) as a proxy of greenhouse gas emissions in intact, drained and extracted peatlands. For this, we used chamber-measured carbon dioxide (CO2) and methane (CH4) data from seven peatlands in Estonia collected during vegetation season in 2017&#8211;2020. Additionally, we used temperature and water table depth data measured in situ. We studied relationships between CO2, CH4, in-situ parameters and remotely sensed LST from Landsat 7 and 8, and MODIS Terra. Results of our study suggest that LST has stronger relationships with surface and soil temperature as well as with ecosystem respiration (Reco) over drained and extracted sites than over intact ones. Over the extracted cites the correlation between Reco CO2 and LST is 0.7, and over the drained sites correlation is 0.5. In natural sites, we revealed a moderate positive relationship between LST and CO2 emitted in hollows (correlation is 0.6) while it is weak in hummocks (correlation is 0.3). Our study contributes to the better understanding of relationships between greenhouse gas emissions and their remotely sensed proxies over peatlands with different management status and enables better spatial assessment of GHG emissions in drainage affected northern temperate peatlands.

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Urban greenhouse gas emissions from the Berlin area: A case study using airborne CO2 and CH4 in situ observations in summer 2018

10.5194/egusphere-egu2020-3363 ◽

2020 ◽

Author(s):

Theresa Klausner ◽

Mariano Mertens ◽

Heidi Huntrieser ◽

Michal Galkowski ◽

Gerrit Kuhlmann ◽

...

Keyword(s):

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Urban Areas ◽

Ghg Emissions ◽

Capital City ◽

Detailed Knowledge ◽

Emission Flux ◽

Gas Emissions ◽

Mixing Ratios

Urban areas are recognised as a significant source of greenhouse gas emissions (GHG), such as carbon dioxide (CO2) and methane (CH4). The total amount of urban GHG emissions, especially for CH4, however, is not well quantified. Here we report on airborne in situ measurements using a Picarro G1301-m analyser aboard the DLR Cessna Grand Caravan to study GHG emissions downwind of the German capital city Berlin. In total, five aircraft-based mass balance experiments were conducted in July 2018 within the Urban Climate Under Change [UC]2 project. The detection and isolation of the Berlin plume was often challenging because of comparatively small GHG signals above variable atmospheric background concentrations. However, on July 20th enhancements of up to 4 ppm CO2 and 21 ppb CH4 were observed over a horizontal extent of roughly 45 to 65 km downwind of Berlin. These enhanced mixing ratios are clearly distinguishable from the background and can partly be assigned to city emissions. The estimated CO2 emission flux of 1.39 &#177; 0.75 t s-1 is in agreement with current inventories, while the CH4 emission flux of 5.20 &#177; 1.61 kg s-1 is almost two times larger than the highest reported value in the inventories. We localized the source area with HYSPLIT trajectory calculations and the high resolution numerical model MECO(n) (down to ~1 km), and investigated the contribution from sewage-treatment plants and waste deposition to CH4, which are treated differently by the emission inventories. Our work highlights the importance of a) strong CH4 sources in the surroundings of Berlin and b) a detailed knowledge of GHG inflow mixing ratios to suitably estimate emission rates.

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