scholarly journals High net CO<sub>2</sub> and CH<sub>4</sub> release at a eutrophic shallow lake on a formerly drained fen

2016 ◽  
Vol 13 (10) ◽  
pp. 3051-3070 ◽  
Author(s):  
Daniela Franz ◽  
Franziska Koebsch ◽  
Eric Larmanou ◽  
Jürgen Augustin ◽  
Torsten Sachs
Keyword(s):  
Global Warming ◽  
Shallow Lake ◽  
Typha Latifolia ◽  
Open Water ◽  
Emergent Vegetation ◽  
Lake Ecosystem ◽  
Co2 Uptake ◽  
Mild Winter ◽  
Ch4 Emissions ◽  
Northeastern Germany

Abstract. Drained peatlands often act as carbon dioxide (CO2) hotspots. Raising the groundwater table is expected to reduce their CO2 contribution to the atmosphere and revitalise their function as carbon (C) sink in the long term. Without strict water management rewetting often results in partial flooding and the formation of spatially heterogeneous, nutrient-rich shallow lakes. Uncertainties remain as to when the intended effect of rewetting is achieved, as this specific ecosystem type has hardly been investigated in terms of greenhouse gas (GHG) exchange. In most cases of rewetting, methane (CH4) emissions increase under anoxic conditions due to a higher water table and in terms of global warming potential (GWP) outperform the shift towards CO2 uptake, at least in the short term.Based on eddy covariance measurements we studied the ecosystem–atmosphere exchange of CH4 and CO2 at a shallow lake situated on a former fen grassland in northeastern Germany. The lake evolved shortly after flooding, 9 years previous to our investigation period. The ecosystem consists of two main surface types: open water (inhabited by submerged and floating vegetation) and emergent vegetation (particularly including the eulittoral zone of the lake, dominated by Typha latifolia). To determine the individual contribution of the two main surface types to the net CO2 and CH4 exchange of the whole lake ecosystem, we combined footprint analysis with CH4 modelling and net ecosystem exchange partitioning.The CH4 and CO2 dynamics were strikingly different between open water and emergent vegetation. Net CH4 emissions from the open water area were around 4-fold higher than from emergent vegetation stands, accounting for 53 and 13 g CH4 m−2 a−1 respectively. In addition, both surface types were net CO2 sources with 158 and 750 g CO2 m−2 a−1 respectively. Unusual meteorological conditions in terms of a warm and dry summer and a mild winter might have facilitated high respiration rates. In sum, even after 9 years of rewetting the lake ecosystem exhibited a considerable C loss and global warming impact, the latter mainly driven by high CH4 emissions. We assume the eutrophic conditions in combination with permanent high inundation as major reasons for the unfavourable GHG balance.

scholarly journals High net CO<sub>2</sub> and CH<sub>4</sub> release at a eutrophic shallow lake on a formerly drained fen

2016 ◽  
Author(s):  
D. Franz ◽  
F. Koebsch ◽  
E. Larmanou ◽  
J. Augustin ◽  
T. Sachs
Keyword(s):  
Global Warming ◽  
Shallow Lake ◽  
Typha Latifolia ◽  
Open Water ◽  
Emergent Vegetation ◽  
Lake Ecosystem ◽  
Co2 Uptake ◽  
Mild Winter ◽  
Ch4 Emissions ◽  
Ne Germany

Abstract. Drained peatlands often act as carbon dioxide (CO2) hotspots. Raising the groundwater table is expected to reduce their CO2 contribution to the atmosphere and revitalize their function as carbon (C) sink in the long term. Without strict water management rewetting often results in partial flooding and the formation of spatially heterogeneous, nutrient-rich shallow lakes. Uncertainties remain as to when the intended effect of rewetting is achieved, as this specific ecosystem type has hardly been investigated in terms of greenhouse gas exchange (GHG) exchange. In most cases, methane (CH4) emissions increase under anoxic conditions due to a higher water table and in terms of global warming potential (GWP) outperform the shift towards CO2 uptake, at least in the short-term. Based on eddy covariance measurements we studied the ecosystem–atmosphere exchange of CH4 and CO2 (NEE) at a shallow lake situated on a former fen grassland in Northeast (NE) Germany. The lake evolved shortly after flooding, 9 years previous to our investigation period. The ecosystem consists of two main surface types: open water (inhabited by submerged and floating vegetation) and emergent vegetation (particularly including the eulittoral zone of the lake, dominated by Typha latifolia). To determine the individual contribution of the two main surface types to the net CO2 and CH4 exchange of the whole lake ecosystem, we combined footprint analysis with CH4 modelling and NEE partitioning. The CH4 and CO2 dynamics were strikingly different between open water and emergent vegetation. Net CH4 emissions from the open water area were around 4-fold higher than from emergent vegetation stands, accounting for 53 and 13 g CH4 m−2 a−1, respectively. In addition, both surface types were net CO2 sources with 158 and 750 g CO2 m−2 a−1, respectively. Unusual meteorological conditions in terms of a warm and dry summer and a mild winter might have facilitated high respiration rates. In sum, even after 9 years of rewetting the lake ecosystem exhibited a considerable C loss and global warming impact, the latter mainly driven by high CH4 emissions. We assume the eutrophic conditions in combination with permanent high inundation as major reasons for the unfavourable GHG balance.

scholarly journals Summer fluxes of methane and carbon dioxide from a pond and floating mat in a continental Canadian peatland

2016 ◽  
Author(s):  
M. Burger ◽  
S. Berger ◽  
I. Spangenberg ◽  
C. Blodau
Keyword(s):  
Carbon Dioxide ◽  
Hot Spot ◽  
Open Water ◽  
Small Scale ◽  
Co2 Uptake ◽  
Bubble Frequency ◽  
Closed Chamber ◽  
Ch4 Emissions ◽  
Carbon Dioxide Co2 ◽  
Floating Mat

Abstract. Ponds smaller than 10000 m2 likely account for about one third of the global lake perimeter. The release of methane (CH4) and carbon dioxide (CO2) from these ponds is often high and significant on the landscape scale. We measured CO2 and CH4 fluxes in a temperate peatland in southern Ontario, Canada, in summer 2014 along a transect from the open water of a small pond (847 m2) towards the surrounding floating mat (5993 m2) and in a peatland reference area. We used a high-frequency closed chamber technique and distinguished between diffusive and ebullitive CH4 fluxes. CH4 fluxes and CH4 bubble frequency increased from a median of 0.14 (0.00 to 0.43) mmol m−2 h−1 and 4 events m−2 h−1 on the open water to a median of 0.80 (0.20 to 14.97) mmol m−2 h−1 and 168 events m−2 h−1 on the floating mat. The mat was a summer hot spot of CH4 emissions. Fluxes were one order of magnitude higher than at an adjacent peatland site. During daytime the pond was a net source of CO2 equivalents to the atmosphere amounting to 0.13 (−0.02 to 1.06) g CO2 equivalents m−2 h−1, whereas the adjacent peatland site acted as a sink of −0.78 (−1.54 to 0.29) g CO2 equivalents m−2 h−1. The photosynthetic CO2 uptake on the floating mat did not counterbalance the high CH4 emissions, which turned the floating mat into a strong net source of 0.21 (−0.11 to 2.12) g CO2 equivalents m−2h−1. This study highlights the large small-scale variability of CH4 fluxes and CH4 bubble frequency at the peatland-pond interface and the importance of the often large ecotone areas surrounding small ponds as a source of greenhouse gases to the atmosphere.

scholarly journals Summer fluxes of methane and carbon dioxide from a pond and floating mat in a continental Canadian peatland

2016 ◽  
Vol 13 (12) ◽  
pp. 3777-3791 ◽  
Author(s):  
Magdalena Burger ◽  
Sina Berger ◽  
Ines Spangenberg ◽  
Christian Blodau
Keyword(s):  
Carbon Dioxide ◽  
Hot Spot ◽  
Open Water ◽  
Small Scale ◽  
Co2 Uptake ◽  
Bubble Frequency ◽  
Closed Chamber ◽  
Ch4 Emissions ◽  
Carbon Dioxide Co2 ◽  
Floating Mat

Abstract. Ponds smaller than 10 000 m2 likely account for about one-third of the global lake perimeter. The release of methane (CH4) and carbon dioxide (CO2) from these ponds is often high and significant on the landscape scale. We measured CO2 and CH4 fluxes in a temperate peatland in southern Ontario, Canada, in summer 2014 along a transect from the open water of a small pond (847 m2) towards the surrounding floating mat (5993 m2) and in a peatland reference area. We used a high-frequency closed chamber technique and distinguished between diffusive and ebullitive CH4 fluxes. CH4 fluxes and CH4 bubble frequency increased from a median of 0.14 (0.00 to 0.43) mmol m−2 h−1 and 4 events m−2 h−1 on the open water to a median of 0.80 (0.20 to 14.97) mmol m−2 h−1 and 168 events m−2 h−1 on the floating mat. The mat was a summer hot spot of CH4 emissions. Fluxes were 1 order of magnitude higher than at an adjacent peatland site. During daytime the pond was a net source of CO2 equivalents to the atmosphere amounting to 0.13 (−0.02 to 1.06) g CO2 equivalents m−2 h−1, whereas the adjacent peatland site acted as a sink of −0.78 (−1.54 to 0.29) g CO2 equivalents m−2 h−1. The photosynthetic CO2 uptake on the floating mat did not counterbalance the high CH4 emissions, which turned the floating mat into a strong net source of 0.21 (−0.11 to 2.12) g CO2 equivalents m−2 h−1. This study highlights the large small-scale variability of CH4 fluxes and CH4 bubble frequency at the peatland–pond interface and the importance of the often large ecotone areas surrounding small ponds as a source of greenhouse gases to the atmosphere.

Development of a water temperature-ecological model to stimulate global warming effects on lake ecosystem

1996 ◽  
Vol 34 (7-8) ◽  
pp. 237-244 ◽  
Author(s):  
Masaaki Hosomi ◽  
Tetsu Saigusa ◽  
Kenichi Yabunaka ◽  
Takuya Okubo ◽  
Akihiko Murakami
Keyword(s):  
Global Warming ◽  
Water Temperature ◽  
Thermal Stratification ◽  
Ecological Model ◽  
Nutrient Release ◽  
Eddy Diffusion ◽  
Nutrient Concentrations ◽  
Lake Ecosystem ◽  
Phytoplankton Species ◽  
Freezing And Thawing

This paper describes a newly developed combined water temperature-ecological (WT-ECO) model which is employed to simulate the effects of global warming on lake and reservoir ecosystems. The WT model includes (i) variations in the eddy diffusion coefficient based on the degree of thermal stratification and the velocity of wind, and (ii) a sub-model for simulating the freezing and thawing processes of surface water, water temperatures, and the mixing rates between two adjacent layers of water. The ECO model then uses these results to calculate the resultant effect on a lake's ecological dynamics, e.g., composition of phytoplankton species, their respective concentrations, and nutrient concentrations. When the model was benchmarked against Lake Yunoko, a dimictic lake, fairly good agreement was obtained over a 4-yr period; thereby indicating it is suitably calibrated. In addition, to assess the effects of global warming on a lake ecosystem, changes in Lake Yunoko's water temperature/quality were simulated in response to an increase in air temperature of 2 - 4°C. Results indicate that such an increase will (i) increase thermal stratification in summer, which increases the nutrient concentrations in bottom water due to nutrient release from bottom sediment, (ii) increase the concentration of phytoplankton at the beginning of the autumn circulation period, and (iii) change the composition of phytoplankton species.

scholarly journals Antecedent lake conditions shape resistance and resilience of a shallow lake ecosystem following extreme wind storms

2021 ◽  
Author(s):  
Michael W. Thayne ◽  
Benjamin M. Kraemer ◽  
Jorrit P. Mesman ◽  
Bastiaan W. Ibelings ◽  
Rita Adrian
Keyword(s):  
Shallow Lake ◽  
Lake Ecosystem ◽  
Extreme Wind ◽  
Wind Storms

Notable increases in nutrient concentrations in a shallow lake during seasonal ice growth

2016 ◽  
Vol 74 (12) ◽  
pp. 2773-2783 ◽  
Author(s):  
Yang Fang ◽  
Li Changyou ◽  
Matti Leppäranta ◽  
Shi Xiaonghong ◽  
Zhao Shengnan ◽  
...  
Keyword(s):  
Liquid Water ◽  
Shallow Lake ◽  
Water Environment ◽  
Open Water ◽  
Middle Layer ◽  
Nutrient Concentrations ◽  
Unfrozen Water ◽  
Total N ◽  
Water And Sediment ◽  
Increased Risk

Nutrients may be eliminated from ice when liquid water is freezing, resulting in enhanced concentrations in the unfrozen water. The nutrients diluted from the ice may contribute to accumulated concentrations in sediment during winter and an increased risk of algae blooms during the following spring and summer. The objective of this study was to evaluate the influence of ice cover on nitrogen (N) and phosphorus (P) concentrations in the water and sediment of a shallow lake, through an examination of Ulansuhai Lake, northern China, from the period of open water to ice season in 2011–2013. The N and P concentrations were between two and five times higher, and between two and eight times higher, than in unfrozen lakes, respectively. As the ice thickness grew, contents of total N and total P showed C-shaped profiles in the ice, and were lower in the middle layer and higher in the bottom and surface layers. Most of the nutrients were released from the ice to liquid water. The results confirm that ice can cause the nutrient concentrations in water and sediment during winter to increase dramatically, thereby significantly impacting on processes in the water environment of shallow lakes.

scholarly journals Application of the Conditional Nonlinear Optimal Perturbations Method in the Shallow Lake Ecological Degradation and Restoration

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Bo Wang ◽  
Qianqian Qi
Keyword(s):  
Shallow Lake ◽  
Sediment Resuspension ◽  
Finite Amplitude ◽  
Water Transparency ◽  
Lake Ecosystem ◽  
Lake Ecosystems ◽  
Ecological Degradation ◽  
Parameter Condition ◽  
Restoration Model ◽  
Simple Combination

In the shallow lake ecosystems, the recovery of the aquatic macrophytes and the increase in the water transparency have been the main contents of the ecological restoration. Using the shallow lake ecological degradation and restoration model, CNOP method is adopted to discuss the instability and sensitivity of the ecosystem to the finite-amplitude perturbations related to the initial condition and the parameter condition. Results show that the linearly stable clear (turbid) water states can be nonlinearly unstable with the finite-amplitude perturbations, which represent the nature factors and the human activities such as the excessive harvest of the macrophytes and the sediment resuspension caused by artificially dynamic actions on the ecosystems. The results also support the viewpoint of Scheffer et al., whose emphasis is that the facilitation interactions between the submerged macrophytes and the water transparency are the main trigger for an occasional shift from a turbid to a clear state. Also, by the comparison with CNOP-I, CNOP-P, CNOP, and (CNOP-I, CNOP-P), results demonstrate that CNOP, which is not a simple combination of CNOP-I and CNOP-P, could induce the shallow lake ecosystem larger departure from the same ground state rather than CNOP-I, CNOP-P, and (CNOP-I, CNOP-P).

scholarly journals KRETERIA DESAIN FOTOBIOREAKTOR SISTEM AIRLIFT REACTOR

2016 ◽  
Vol 11 (1) ◽  
pp. 27
Author(s):  
Arif Dwi Santoso ◽  
Abdil H.S ◽  
Diyono .
Keyword(s):  
Global Warming ◽  
Carbon Capture ◽  
Human Life ◽  
Co2 Reduction ◽  
Chemical Mechanism ◽  
Co2 Uptake ◽  
Environmental Technology ◽  
Negative Impacts ◽  
Air Lift ◽  
Selection Of

Global warming has become an increasingly important issue around the world today due to the rise of anthropogenic greenhouse gases emission, which gives several negative impacts on human life. There are some techniques have been studied and assessed i.e. physical mechanism by injected CO2 to the geological formations, chemical mechanism with artificial tree technology and biological mechanism by increasing the primary production through iron enrichment in high nutrient-low chlorophyll (HNLC) waters as well as mixing of water column below the sea surface. Those technologies, which are well known as Carbon Capture Storage ‘(CCS) technology, are expected to be applied to reduce the oncentration of anthropogenic CO2 in the atmosphere and to minimize the global warming. The Center of Environmental Technology, Agency for the Assessment and Application of Technology (BPPT) will carry out a research concerning CO2 reduction by a phytoplankton culture in a photobioreactor in three years. The main objective of this research is to assess the CO2 uptake capability of tropical phytoplankton. In this paper, we would showed the creteria and design to assembly a photobioreactor esspesially a air lift photobioreactor. To improve performance photobioreaktor, the materials included design criteria and the dynamics of fluids in fotobioreaktor have to considered propoerly. Other the hand, the selection of the most productive species and selection of appropriate media and economically also important to be done. Keywords: global warming, creteria and design, greenhouse gas, air lift photobioreactor

scholarly journals Simulated Variation Characteristics of Oceanic CO2 Uptake, Surface Temperature, and Acidification in Zhejiang Province, China

2021 ◽  
Vol 9 ◽  
Author(s):  
Kuo Wang ◽  
Han Zhang ◽  
Gao-Feng Fan ◽  
Zheng-Quan Li ◽  
Zhen-Yan Yu ◽  
...  
Keyword(s):  
Global Warming ◽  
Carbon Sequestration ◽  
Carbon Cycle ◽  
Surface Temperature ◽  
Ocean Acidification ◽  
Sea Surface ◽  
Co2 Uptake ◽  
Hydrogen Ion Concentration ◽  
Variation Characteristics ◽  
Oceanic Carbon

Since preindustrial times, atmospheric CO2 content increased continuously, leading to global warming through the greenhouse effect. Oceanic carbon sequestration mitigates global warming; on the other hand, oceanic CO2 uptake would reduce seawater pH, which is termed ocean acidification. We perform Earth system model simulations to assess oceanic CO2 uptake, surface temperature, and acidification for Zhejiang offshore, one of the most vulnerable areas to marine disasters. In the last 40 years, atmospheric CO2 concentration increased by 71 ppm, and sea surface temperature (SST) in Zhejiang offshore increased at a rate of 0.16°C/10a. Cumulative oceanic CO2 uptake in Zhejiang offshore is 0.3 Pg C, resulting in an increase of 20% in sea surface hydrogen ion concentration, and the acidification rate becomes faster in the last decade. During 2020–2040, under four RCP scenarios, SST in Zhejiang offshore increases by 0.3–0.5°C, whereas cumulative ocean carbon sequestration is 0.150–0.165 Pg C. Relative to RCP2.6, the decrease of surface pH in Zhejiang offshore is doubled under RCP8.5. Furthermore, simulated results show that the relationship between CO2 scenario and oceanic carbon cycle is nonlinear, which hints that deeper reduction of anthropogenic CO2 emission may be needed if we aim to mitigate ocean acidification in Zhejiang offshore under a higher CO2 concentration scenario. Our study quantifies the variation characteristics of oceanic climate and carbon cycle fields in Zhejiang offshore, and provides new insight into the responses of oceanic carbon cycle and the climate system to oceanic carbon sequestration.

scholarly journals Long-term response of oceanic carbon uptake to global warming via physical and biological pumps

2018 ◽  
Vol 15 (13) ◽  
pp. 4163-4180 ◽  
Author(s):  
Akitomo Yamamoto ◽  
Ayako Abe-Ouchi ◽  
Yasuhiro Yamanaka
Keyword(s):  
Global Warming ◽  
Ocean Circulation ◽  
General Circulation ◽  
Deep Ocean ◽  
Biogeochemical Model ◽  
Carbon Uptake ◽  
Co2 Uptake ◽  
Biological Pumps ◽  
Circulation Change ◽  
Oceanic Carbon

Abstract. Global warming is expected to significantly decrease oceanic carbon uptake and therefore increase atmospheric CO2 and global warming. The primary reasons given in previous studies for such changes in the oceanic carbon uptake are the solubility reduction due to seawater warming and changes in the ocean circulation and biological pump. However, the quantitative contributions of different processes to the overall reduction in ocean uptake are still unclear. In this study, we investigated multi-millennium responses of oceanic carbon uptake to global warming and quantified the contributions of the physical and biological pumps to these responses using an atmosphere–ocean general circulation model and a biogeochemical model. We found that global warming reduced oceanic CO2 uptake by 13 % (30 %) in the first 140 years (after 2000 model years), consistent with previous studies. Our sensitivity experiments showed that this reduction is primarily driven by changes in the organic matter cycle via ocean circulation change and solubility change due to seawater warming. These results differ from most previous studies, in which circulation changes and solubility change from seawater warming are the dominant processes. The weakening of biological production and carbon export induced by circulation change and lower nutrient supply, diminishes the vertical DIC gradient and substantially reduces the CO2 uptake. The weaker deep-ocean circulation decreases the downward transport of CO2 from the surface to the deep ocean, leading to a drop in CO2 uptake in high-latitude regions. Conversely, weaker equatorial upwelling reduces the upward transport of natural CO2 and therefore enhances the CO2 uptake in low-latitude regions. Because these effects cancel each other out, circulation change plays only a small direct role in the reduction of CO2 uptake due to global warming but a large indirect role through nutrient transport and biological processes.

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