DOI: 10.5061/dryad.9s4mw6mb6
title: Data from: Carbon dioxide and methane fluxes from different surface types in a created urban wetland

description: 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.
description: 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 ([CO<sub>2</sub>])
 and dissolved methane ([CH<sub>4</sub>]) were measured with
 Contros HydroC™ CO<sub>2 </sub>and HydroC™
 CH<sub>4</sub> sensors (CONTROS Systems & Solutions
 GmbH, Germany). Dissolved CO<sub>2 </sub>and
 CH<sub>4</sub> molecules diffuse from water column into the
 detection chamber through a thin-film composite membrane where the
 concentration of CO<sub>2</sub> and CH<sub>4</sub>
 is determined by means of IR absorption spectrometry and Tunable Diode
 Laser Absorption Spectroscopy, respectively.
description: 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"