10.5061/DRYAD.9S4MW6MB6
Li, Xuefei
0000-0003-3160-8089
University of Helsinki
Wahlroos, Outi
University of Turku
Haapanala, Sami
Suvilumi
Pumpanen, Jukka
University of Eastern Finland
Vasander, Harri
University of Helsinki
Ojala1, Anna
University of Helsinki
Vesala, Timo
University of Helsinki
Mammarella, Ivan
University of Helsinki
Data from: Carbon dioxide and methane fluxes from different surface types
in a created urban wetland
Dryad
dataset
2019
carbon dioxide flux
EU Life+11 ENV/FI/911 Urban Oases project grant
Academy Professor projects
312571; 282842
ICOS-Finland
281255
2019-09-29T00:00:00Z
2019-09-29T00:00:00Z
en
https://doi.org/10.5194/bg-2019-279
18560310 bytes
2
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Many wetlands have been drained due to urbanization, agriculture, forestry
or other purposes, which has resulted in losing their ecosystem services.
To protect receiving waters and to achieve services such as flood control
and stormwater quality mitigation, new wetlands are created in urbanized
areas. However, our knowledge of greenhouse gas exchange in newly created
wetlands in urban areas is currently limited. In this paper we present
measurements carried out at a created urban wetland in boreal climate. We
conducted measurements of ecosystem CO2 flux (NEE) and CH4 flux (FCH4) at
the constructed stormwater wetland Gateway in Nummela, Vihti, Southern
Finland using eddy covariance (EC) technique. The measurements were
commenced the fourth year after construction and lasted for one full year
and two subsequent growing seasons. Besides ecosystem scale fluxes
measured by EC tower, the diffusive CO2 and CH4 fluxes from the open-water
area (Fw_CO2 and Fw_CH4, respectively) were modelled based on measurements
of CO2 and CH4 concentration in the water. Fluxes from vegetated area were
estimated by applying a simple mixing model using above-mentioned fluxes
and footprint-weighted fractional area. The half-hourly footprint-weighted
contribution of diffusive fluxes from open water ranged from 0 to 25.5 %
in year 2013. The annual NEE of the studied wetland was 8.0 g C-CO2 m-2
yr-1 with the 95 % confidence interval between -18.9 and 34.9 g C-CO2 m-2
yr-1 and FCH4 was 3.9 g C-CH4 m-2 yr-1 with the 95 % confidence interval
between 3.75 and 4.07 g C-CH4 m-2 yr-1. The ecosystem sequestered CO2
during summer months (June-August), while the rest of the year it was a
CO2 source. CH4 displayed strong seasonal dynamics, higher in summer and
lower in winter, with a sporadic emission episode in the end of May 2013.
Both CH4 and CO2 fluxes, especially those obtained from vegetated area,
exhibited strong diurnal cycle during summer with synchronized peaks
around noon. The annual Fw_CO2 was 297.5 g C-CO2 m-2 yr-1 and Fw_CH4 was
1.73 g C-CH4 m-2 yr-1. The peak diffusive CH4 flux was 137.6 nmol C-CH4
m-2 s-1, which was synchronized with the FCH4. Overall, during the
monitored time period, the established stormwater wetland had a climate
warming effect with 0.263 kg CO2-eq m-2 yr-1 of which 89 % was contributed
by CH4. The radiative forcing of the open-water exceeded the vegetation
area (1.194 kg CO2-eq m-2 yr-1 and 0.111 kg CO2-eq m-2 yr-1,
respectively), which implies that, when considering solely the climate
impact of a created wetland over a 100-year horizon, it would be more
beneficial to design and establish wetlands with large patches of emergent
vegetation, and to limit the areas of open-water to the minimum
necessitated by other desired ecosystem services.
The data was collected from an created urban wetland in Southern Finland
(60.3272°N, 24.3369°E) during 2013 and 2014. Greenhouse gas measurements
was obtained by eddy covariance (ED) technique from a 2.9 m ED tower. The
post-processing of the EC flux data has been done with EddyUH
post-processing software. We used an artificial neural network (ANN)
technique to gap-fill half-hourly flux data using meteorological
variables. Local weather conditions were recorded with a Vaisala WXT
weather transmitter (WXT520, Vaisala Oyj, Finland) at the inlet monitoring
station. Rainfall, wind speed and direction, temperature and relative
humidity were recorded continuously at 10-minute interval. Photosynthetic
photon flux density (PPFD) was measured with a PQS1 PAR quantum sensor
(Kipp & Zonen, the Netherland). Due to instrument failure we
obtained PPFD data only from 26 Jan to 7 April and from 22 July to 29 Dec
2013. The gaps were filled with PPFD data from another meteorological
station nearby (60°38' N, 23°58' E) in Lettosuo, Finland. The
concentration of dissolved carbon dioxide ([CO2]) and dissolved methane
([CH4]) were measured with Contros HydroC™ CO2 and HydroC™ CH4 sensors
(CONTROS Systems & Solutions GmbH, Germany). Dissolved CO2 and CH4
molecules diffuse from water column into the detection chamber through a
thin-film composite membrane where the concentration of CO2 and CH4 is
determined by means of IR absorption spectrometry and Tunable Diode Laser
Absorption Spectroscopy, respectively.
Greenhouse gas measurements data can be found in
"Nummela_QCfluxes.zip". Weather data can be found in
"NummelaMeteodata_all.txt". Measurements in the water including
dissolved gas concentration, water temperature, water table depth, etc.
can be found in "water measurements.zip"