Carbon Dioxide Emissions from the Littoral Zone of a Chinese Reservoir

Abstract

Abstract:The continuous increase in the number of reservoirs globally has raised important questions about the environmental impact of their greenhouse gases emissions. In particular, the littoral zone may be a hotspot for production of greenhouse gases. We investigated the spatiotemporal variation of CO 2 flux at the littoral zone of a Chinese reservoir along a wet-to-dry transect from permanently flooded land, seasonally flooded land to non-flooded dry land, using the static dark chamber technique. The mean total CO 2 emission was 346 mg m −2 h −1 and the rate varied significantly by water levels, months and time of day. The spatiotemporal variation of flux was highly correlated with biomass, temperature and water level. Flooding could play a positive role in carbon balance if water recession occurs at the time when carbon gains associated with plant growth overcomes the carbon loss of ecosystem. The overall carbon balance was analysed using cumulative greenhouse gases fluxes and biomass, bringing the data of the present study alongside previously published, simultaneously measured CH 4 and N 2 O fluxes. For the growing season, 12.8 g C m −2 was absorbed by the littoral zone. Taking CH 4 and N 2 O into the calculation showed that permanently flooded sites were a source of greenhouse gases, rather than a sink. Our study emphasises how water level fluctuation influenced CO 2 , CH 4 and N 2 O in different ways, which greatly affected the spatiotemporal variation and emission rate of greenhouse gases from the littoral zone.

An Environment Transitional Zone Buffers Peatlands Carbon Loss

“…Moreover, 10°C warming failed to stimulate ETzone CO 2 emission signi cantly, while signi cantly stimulated that in the upper aerobic surface and anaerobic deep soil in the conditions of pristine eld. In contrast with most other ndings labeling ETzone as a hotspot in the ecosystem 1,4,5,34 , the lowest CO 2 emission rate and least warming response of the ETzone at the subsurface of peatland in our study showed that it was inert and resistant to warming. Such phenomenon can be explained by the constitution and characteristics of the carbon at ETzone soil.…”

Ecological Responses of Lakes to Climate Change

“…In addition to warming, hydrologic changes associated with climate change might affect those C fluxes. Yang et al [30] quantified emissions of CO 2 from the littoral zone of a reservoir in Beijing, China, taking measurements with a dark chamber and gas chromatography techniques along a transect from a permanently flooded location to a seasonally flooded location and then to dry land. They also compared emissions from places with different vegetation types within each hydrographic band.…”

pCO2 Dynamics of Stratified Reservoir in Temperate Zone and CO2 Pulse Emissions During Turnover Events

“…To investigate the thermal stratification structure in the reservoir, a thermometer chain was installed at R4, and continuous water temperature monitoring was performed at given water depths. Water thermometers (HOBO Water Temp Pro, Onset Co., Bourne, MA, USA) were installed at depths of 0, 2,4,6,8,10,12,14,16,18,21,24,27,30, and 33 m, and water temperature was measured at 10 min intervals. As both meteorological and hydrological data were needed to analyze the characteristics of the hydrodynamic mixing in the reservoir, data were collected from the Korea Meteorological Administration (KMA).…”

“…However, most of the reported carbon emission from reservoirs have been estimated using limited field data [5,23], for which the methodological and analytical uncertainties are quite high [6,24]. In particular, because carbon emissions from reservoir surface water vary widely over time and space [19,25], data measured at a specific time and place cannot represent overall CO 2 fluxes, which are very temporally and spatially dynamic [26,27]. In deep lakes and reservoirs, mixing occurs between the upper and lower layers when thermal stratification is destroyed, and the accumulated supersaturated CO 2 is spread to the surface layer.…”