Methane Emissions from Pantanal, South America, during the Low Water Season: Toward More Comprehensive Sampling

Bastviken, David; Santoro, Ana Lúcia; Marotta, Humberto; Pinho, Luana; Calheiros, Débora Fernandes; Crill, Patrick; Enrich‐Prast, Alex

doi:10.1021/es1005048

Cited by 213 publications

(222 citation statements)

References 26 publications

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“…Monitoring and characterization of CH 4 and CO 2 fluxes in representative reservoirs of different power densities, locations and time since construction are critically needed to better quantify the total GHG emissions from the hydroelectric reservoirs in China. Although various sampling and analysis techniques have been used, measurement of GHG emissions from reservoirs -which can cover several hundreds of square kilometres and have depths exceeding 100 m -is a complicated process 30,31 . The limited number of sampling spots may not be able to represent the overall emissions from the reservoirs with complex hydrodynamics 23,30 .…”

Section: Discussionmentioning

confidence: 99%

“…Although various sampling and analysis techniques have been used, measurement of GHG emissions from reservoirs -which can cover several hundreds of square kilometres and have depths exceeding 100 m -is a complicated process 30,31 . The limited number of sampling spots may not be able to represent the overall emissions from the reservoirs with complex hydrodynamics 23,30 . Furthermore, the rate of biomass decomposition, and thus the production rates of GHGs, are influenced by geographical location, temperature, water depth, the amount and type of vegetation flooded and reservoir age [6][7][8][9]16,23 .…”

Section: Discussionmentioning

confidence: 99%

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The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China

Cheng

2013

Nature Clim Change

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NATURE CLIMATE CHANGE | VOL 3 | AUGUST 2013 | www.nature.com/natureclimatechange C hina overtook the United States and became the world's largest electricity producer and consumer in 2011. The total electricity generation reached 4,722 TW h in 2011, with thermal power and hydropower contributing to 82.5% and 14.0% of the generated electricity, respectively 1 . Meanwhile, over 90% of the thermal electricity is generated by highly polluting coal-fired generation, which had a high grid emission factor of 804 g CO 2 equivalent (CO 2 e) per kW h in 2010 2 . Coal-fired plants are not only the largest stationary source emitters of greenhouse gases (GHGs) in China, but they also bring serious air pollution problems with releases of SO 2 , NO x and fine particles. Hydropower, with more than 200 GW of total installed capacity, accounts for approximately 6% of the total energy supply and over 80% of all electricity generated from renewable sources in China. Joining the global efforts to combat climate change, China is committed to increase the share of non-fossil fuels in its total energy mix to 15% by 2020. Accordingly, the production capacity of hydropower should increase by, on average, 10 to 15 GW yr −1 to help achieve this goal. Cascades of dams are currently being built, planned or proposed on the major river valleys in southwest China, where over two-thirds of the country's hydroelectric resources are located (Fig. 1). With physical water scarcity, and spatially and temporarily uneven distribution of water resources 3 , reservoir development is also a key component of China's recent heavy investment in water infrastructures to adapt to climate change, droughts and floods, and to improve food security 4 .Although hydropower is widely claimed to be a 'clean' energy source, critics have long warned of the environmental impact of large hydroelectric projects. In particular, research over the past two decades has revealed that the decay of organic matter (OM) in reservoirs could release significant amounts of CO 2 and CH 4 , and the emissions from tropical reservoirs characterized by high levels of OM and shallow depths are much higher compared with those in boreal and temperate regions [5][6][7][8][9][10][11][12][13] . Methane is 25 times more effective at trapping heat in the atmosphere than CO 2 over a 100-year period, and is responsible for over 20% of the change in the radiative forcing of the climate system 14 . It has been estimated that large dams release approximately 104 Tg CH 4 annually, or 20% of the total emissions from natural and anthropogenic sources 15 , although current estimations on GHG emissions from global hydroelectric reservoirs bear large uncertainties 13,16 .Carbon dioxide, methane and nitrous oxide are the major GHGs that can be produced in reservoirs, but nitrous oxide emissions are The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China Yuanan Hu, Hefa Cheng* Already the largest generator of hydroelectricity, China is accelerating dam construction to increase ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China

Cheng

2013

Nature Clim Change

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“…The sum of FCO 2 and FCH 4 from the 'Cuvette Centrale' would correspond to 0.48 ± 0.08 PgCO 2 e yr −1 (based on the scaling of a subset of fluxes from the rivers, streams and navigation channels draining the 'Cuvette Centrale' and computed with the k recommended for flooded areas 2 ). The above FCH 4 estimate for the 'Cuvette Centrale' does not include the ebullition of CH 4 ; using a reported ebullition:diffusion ratio of 0.73 for tropical wetlands 18 would bring the total FCO 2 and FCH 4 from SSA rivers and wetlands to range between 0.85 ± 0.10 (Auf) and 0.95 ± 0.11 (Ray) PgCO 2 e yr −1 . These fluxes are significant beyond the African continental scale, considering that the global net CO 2 sink is at present estimated at 1.5 and 2.0 PgC yr −1 for the oceans and the terrestrial biosphere, respectively 7 .…”

Section: Regional and Global Significance Of Ghg Fluxesmentioning

confidence: 99%

“…We propose that our emission estimates of CO 2 and CH 4 from SSA rivers may be conservative for two reasons. First, the FCH 4 values correspond only to diffusive emissions and do not account for CH 4 ebullition, which can be highly significant in tropical aquatic environments [17][18][19] . Based on floating chamber flux measurements in the Congo and Zambezi rivers (n = 68), we found CH 4 ebullition rates to be on average 0.25 times the diffusive CH 4 flux ( Supplementary Fig.…”

Section: Regional and Global Significance Of Ghg Fluxesmentioning

confidence: 99%

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Globally significant greenhouse-gas emissions from African inland waters

et al. 2015

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Carbon dioxide emissions to the atmosphere from inland waters-streams, rivers, lakes and reservoirs-are nearly equivalent to ocean and land sinks globally. Inland waters can be an important source of methane and nitrous oxide emissions as well, but emissions are poorly quantified, especially in Africa. Here we report dissolved carbon dioxide, methane and nitrous oxide concentrations from 12 rivers in sub-Saharan Africa, including seasonally resolved sampling at 39 sites, acquired between 2006 and 2014. Fluxes were calculated from published gas transfer velocities, and upscaled to the area of all sub-Saharan African rivers using available spatial data sets. Carbon dioxide-equivalent emissions from river channels alone were about 0.4 Pg carbon per year, equivalent to two-thirds of the overall net carbon land sink previously reported for Africa. Including emissions from wetlands of the Congo river increases the total carbon dioxide-equivalent greenhouse-gas emissions to about 0.9 Pg carbon per year, equivalent to about one quarter of the global ocean and terrestrial combined carbon sink. Riverine carbon dioxide and methane emissions increase with wetland extent and upland biomass. We therefore suggest that future changes in wetland and upland cover could strongly a ect greenhouse-gas emissions from African inland waters.C limate predictions necessitate a full and robust account of natural and anthropogenic greenhouse-gas (GHG) fluxes, especially for CO 2 (refs 1-3), CH 4 (ref. 4) and N 2 O (ref. 5), which together accounted for 94% of the anthropogenic global radiative forcing by well-mixed GHGs in 2011 relative to 1750 (ref. 6). Inland waters (streams, rivers, lakes and reservoirs) are increasingly recognized as important sources of GHGs to the atmosphere, with global CO 2 and CH 4 emissions estimated at 2.1 PgC yr −1 (ref.3) and 0.7 PgC yr −1 (CO 2 -equivalents; CO 2 e) (ref. 4) (1 Pg = 10 15 g), respectively. Considering that the oceanic and land carbon (C) sinks correspond to ∼1.5 and ∼2.0 PgC yr −1 (ref. 7), respectively, the GHG flux from inland waters is significant in the global C budget.In a recent global compilation of inland CO 2 data 3 , <20 data points (out of 6,708, that is, <0.3%) represented African inland waters (with the exception of South Africa, which has been densely sampled), even though they account for ∼12% of both global freshwater discharge 8 and riverine surface area 3 , and include some of the largest rivers and lakes in the world. Equally for the global CH 4 database, there is a strong under-representation of tropical inland waters, whereby a recent synthesis 4 resorted to extrapolating CH 4 fluxes from temperate rivers.The prevailing large uncertainty involved in GHG flux estimates for inland waters, essentially due to the paucity of available data, is coupled to a poor understanding of underlying processes, both of which preclude gauging of future fluxes in response to human pressures. In particular, there is a need to further understand the link between inland water GHG fluxes and ...

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Spatial heterogeneity and lake morphology affect diffusive greenhouse gas emission estimates of lakes

Schilder

Bastviken

Hardenbroek

et al. 2013

Geophysical Research Letters

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143

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[1] Most estimates of diffusive flux (F) of methane (CH 4 ) and carbon dioxide (CO 2 ) from lakes are based on single-point flux chamber measurements or on piston velocity (k) modeled from wind speed and single-point measurements of surface water gas concentrations (C aq ). We analyzed spatial variability of F of CH 4 and CO 2 , as well as C aq and k in 22 European lakes during late summer. F and k were higher in the lake centers, leading to considerable bias when extrapolating single-point chamber measurements to whole-lake estimates. The ratio of our empirical k estimates to wind speed-modeled k was related to lake size and shape, suggesting a lake morphology effect on the relationship between wind speed and k. This indicates that the error inherent to established wind speed models can be reduced by determining k and C aq at multiple sites on lakes to calibrate wind speed-modeled k to the local system. Citation: Schilder, J., D. Bastviken, M. van Hardenbroek, P. Kankaala, P. Rinta, T. Stötter, and O. Heiri (2013), Spatial heterogeneity and lake morphology affect diffusive greenhouse gas emission estimates of lakes, Geophys. Res. Lett., 40,[5752][5753][5754][5755][5756]

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Methane Emissions from Pantanal, South America, during the Low Water Season: Toward More Comprehensive Sampling

Cited by 213 publications

References 26 publications

The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China

The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China

Globally significant greenhouse-gas emissions from African inland waters

Spatial heterogeneity and lake morphology affect diffusive greenhouse gas emission estimates of lakes

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