Flux of organic carbon burial and carbon emission from a large reservoir: implications for the cleanliness assessment of hydropower
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摘要
Accurately quantifying the budget of carbon sources and sinks in hydropower reservoirs is important for evaluating the cleanliness of hydroelectricity. However, current research on carbon emissions from reservoirs has rarely taken into account the organic carbon(OC) buried in sediment. Only greenhouse gas emissions from the water-air interface at reservoirs have been examined, which would result in an overestimation of the greenhouse effect of reservoirs. In November 2017, this study investigated the distribution of sediment in the Hongfeng Reservoir(HFR) in southwest China, a typical large hydropower reservoir, by using an underwater seismology monitoring system. We estimated the flux of OC into sediment using the results of a sediment survey and a dataset compiled from references. Our results show that, the HFR retained 200,715 t of OC in the sediment since its impounding after dam construction to the sampling year of 2017, when the average burial flux was 3,521 t-C aà1(106 g C aà1) and the modern burial flux was 5,449 t-C aà1. After excluding the exogenous OC, the modern valid carbon sink of the sediment was 4,632 t per year. Under the current state of the reservoir, taking the modern valid carbon sink value, the carbon emissions from the reservoir's surface, and the discharge water from the dam into consideration, the net carbon sink of the HFR is found to be 1,098.9 t-C aà1. If the hydroelectricity generated by the reservoir is converted to a carbon sink, then the total net carbon sink becomes 12,972.9 t-C aà1.This work argues that both reservoir sediment and hydroelectricity are important carbon sinks and both should be included in assessments of the greenhouse effects of reservoirs.
Accurately quantifying the budget of carbon sources and sinks in hydropower reservoirs is important for evaluating the cleanliness of hydroelectricity. However, current research on carbon emissions from reservoirs has rarely taken into account the organic carbon(OC) buried in sediment. Only greenhouse gas emissions from the water-air interface at reservoirs have been examined, which would result in an overestimation of the greenhouse effect of reservoirs. In November 2017, this study investigated the distribution of sediment in the Hongfeng Reservoir(HFR) in southwest China, a typical large hydropower reservoir, by using an underwater seismology monitoring system. We estimated the flux of OC into sediment using the results of a sediment survey and a dataset compiled from references. Our results show that, the HFR retained 200,715 t of OC in the sediment since its impounding after dam construction to the sampling year of 2017, when the average burial flux was 3,521 t-C aà1(106 g C aà1) and the modern burial flux was 5,449 t-C aà1. After excluding the exogenous OC, the modern valid carbon sink of the sediment was 4,632 t per year. Under the current state of the reservoir, taking the modern valid carbon sink value, the carbon emissions from the reservoir's surface, and the discharge water from the dam into consideration, the net carbon sink of the HFR is found to be 1,098.9 t-C aà1. If the hydroelectricity generated by the reservoir is converted to a carbon sink, then the total net carbon sink becomes 12,972.9 t-C aà1.This work argues that both reservoir sediment and hydroelectricity are important carbon sinks and both should be included in assessments of the greenhouse effects of reservoirs.
Accurately quantifying the budget of carbon sources and sinks in hydropower reservoirs is important for evaluating the cleanliness of hydroelectricity. However, current research on carbon emissions from reservoirs has rarely taken into account the organic carbon(OC) buried in sediment. Only greenhouse gas emissions from the water-air interface at reservoirs have been examined, which would result in an overestimation of the greenhouse effect of reservoirs. In November 2017, this study investigated the distribution of sediment in the Hongfeng Reservoir(HFR) in southwest China, a typical large hydropower reservoir, by using an underwater seismology monitoring system. We estimated the flux of OC into sediment using the results of a sediment survey and a dataset compiled from references. Our results show that, the HFR retained 200,715 t of OC in the sediment since its impounding after dam construction to the sampling year of 2017, when the average burial flux was 3,521 t-C aà1(106 g C aà1) and the modern burial flux was 5,449 t-C aà1. After excluding the exogenous OC, the modern valid carbon sink of the sediment was 4,632 t per year. Under the current state of the reservoir, taking the modern valid carbon sink value, the carbon emissions from the reservoir's surface, and the discharge water from the dam into consideration, the net carbon sink of the HFR is found to be 1,098.9 t-C aà1. If the hydroelectricity generated by the reservoir is converted to a carbon sink, then the total net carbon sink becomes 12,972.9 t-C aà1.This work argues that both reservoir sediment and hydroelectricity are important carbon sinks and both should be included in assessments of the greenhouse effects of reservoirs.
引文
[1]Barros N, Cole JJ, Tranvik LJ, et al. Carbon emission from hydroelectric reservoirs linked to reservoir age and latitude. Nat Geosci 2011;4:593–6.
[2]Giles J. Methane quashes green credentials of hydropower. Nature2006;444:524–5.
[3]McCully P. Tropical hydropower is a signi?cant source of greenhouse gas emissions. A response to the International Hydropower. International Rivers Network; 2004.
[4]St Louis VL, Kelly CA, Duchemin E, et al. Reservoir surfaces as sources of greenhouse gases to the atmosphere:a global estimate. Bioscience2000;50:766–75.
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[6]IHA. Hydro’s contribution, factsheet. London:International Hydropower Association7; 2010.
[7]Soumis N, Duchemin E, Canuel R, et al. Greenhouse gas emissions from reservoirs of the western United sSates. Glob Biogeochem Cycles 2004;18:GB3022.
[8]UNESCO/IHA. The UNESCO/IHA measurement speci?cation guidance for evaluating the GHG status of man-made freshwater reservoirs. Edition 1–June 2009.
[9]Raymond PA, Hartmann J, Lauerwald R, et al. Global carbon dioxide emissions from inland waters. Nature 2013;503:355–9.
[10]Dean WE, Gorham E. Magnitude and signi?cance of carbon burial in lakes,reservoirs, and peatlands. Geology 1998;26:535–8.
[11]Mendonca R, Kosten S, Sobek S, et al. Carbon sequestration in a large hydroelectric reservoir:an integrative seismic approach. Ecosystems2014;17:430–41.
[12]Jiang YB, Ji HB. Isotopic indicators of source and fate of particulate organic carbon in a karstic watershed on the Yunnan-Guizhou Plateau. Appl Geochem2013;36:153–67.
[13]Li J, Zhang L, Wu H, et al. Analysis of water quality evolution mechanism in the Maotiaohe watershed. Res Sci 2011;33:1481–8(In Chinese).
[14]Deng H, Xia P, Chen W, et al. Distribution characteristics of nutrient concentration in water–level?uctuating zone and sediment of Hongfeng Reservoir basin. J Wuhan Inst Tech 2014;36:27–33(in Chinese).
[15]Wang JF, Chen JG, Ding SM, et al. Effects of seasonal hypoxia on the release of phosphorus from sediments in deep-water ecosystem:a case study in Hongfeng Reservoir, southwest China. Environ Pollut 2016;219:858–65.
[16]Ye F, Zhang M, Liu H, et al. Analysis of organic enrichment in the sediment of red maple lake reservoir. Water Resources Protection 2010;26:8–12(In Chinese).
[17]Xu LB, Wu FC, Wan GJ, et al. Relationship between Pb-210(ex)activity and sedimentary organic carbon in sediments of 3 Chinese lakes. Environ Pollut2011;159:3462–7.
[18]Wang SL, Yeager KM, Wan GJ, et al. Carbon export and HCO3àfate in carbonate catchments:a case study in the karst plateau of southwestern China. Appl Geochem 2012;27:64–72.
[19]Lv M, Wang H, Cai Y, et al. Magnetic properties of core HF1-2 from lake Hongfeng in Guizhou Province and its implications for soil erosion. J Lake Sci2008;20:298–305(In Chinese).
[20]Wei ZQ, Liu CQ, Liang XB, et al. Degradation of organic matter in the sediments of Hongfeng Reservoir. Chin Sci Bull 2005;50:2377–80.
[21]Xiao HY, Liu CQ. Situation of sewage input re?ected by nitrogen isotopic composition in a sediment core of Hongfeng Lake. Chin Sci Bull2006;51:971–6.
[22]Wang Y. Biogeochemical processes of nutrients(P, N and C)at the sedimentwater interface in two reservoirs:Hongfeng hu and Baihua hu, Guizhou, China Doctor Dissertation. Guiyang:Institute of Geochemistry, Chinese Academy of Sciences; 2002.
[23]Wang F. The geochemical behavior of trace metals near water-sediments interface in seasonally anoxic lakes Doctor Dissertation. Beijing:University of Chinese Academy of Sciences; 2003.
[24]Zhang R, Wang L. Vertical distributions of phosphorus forms and bioavailable phosphorus in the sediments of houwu from Hongfeng Lake and calculation of environmental dredging depth. Earth Environ 2012;40:554–60(In Chinese).
[25]Wang FS, Wang B, Liu CQ, et al. Carbon dioxide emission from surface water in cascade reservoirs-river system on the Maotiao River, southwest of China.Atmos Environ 2011;45:3827–34.
[26]Yang Y. Impact on the production and emission of CH4and N2O of river by hydropower developmentàcase study on cascade reservoirs on the Maotiao River Master Thesis. Guiyang:Guizhou University; 2009.
[27]Yu SW, Wei YM, Guo HX, et al. Carbon emission coef?cient measurement of the coal-to-power energy chain in China. Appl Energ 2014;114:290–300.
[28]Encyclopedia of rivers and lakes in China:section of Changjiang River Basin.2010. China Water Power Press. Beijing
[29]Water Resources Department of Guizhou Province, China. Water Resources Bulletin 2011.
[30]Zhu YR, Zhang RY, Wu FC, et al. Phosphorus fractions and bioavailability in relation to particle size characteristics in sediments from Lake Hongfeng,southwest China. Environ Earth Sci 2013;68:1041–52.
[31]Qiu H, Su Y, Chen X, et al. Characteristics of the distributions of soil organic carbon and main components in a typical catchment in the karst plateau. J Agro-Environ Sci 2012;31:1956–64(In Chinese).
[32]Wang FS, Cao M, Wang BL, et al. Seasonal variation of CO2diffusion?ux from a large subtropical reservoir in east China. Atmos Environ 2015;103:129–37.
[33]Abril G, Guérin F, Richard S, et al. Carbon dioxide and methane emissions and the carbon budget of a 10-year old tropical reservoir(Petit Saut, French Guiana). Glob Biogeochem Cycles 2005;19:GB4007.
[34]Zhang W. The environmental characteristics and eutrophication of Hongfeng Lake and Baihu Lake. Guiyang:Guizhou Science and Technological Press; 1999.
[35]Liu ZH, Dreybrodt W. Signi?cance of the carbon sink produced by H2Ocarbonate-CO2-aquatic phototroph interaction on land. Sci Bull2015;60:182–91.
[36]Chen Y, Zhang S, Huang D, et al. The development of China’s yangtze river economic belt:How to make it in a green way? Sci Bull 2017;62:648–51.
[37]Cole JJ, Caraco NF. Carbon in catchments:connecting terrestrial carbon losses with aquatic metabolism. Mar Freshwater Res 2001;52:101–10.
[38]Lu WQ, Wang SL, Yeager KM, et al. Importance of considered organic versus inorganic source of carbon to lakes for calculating net effect on landscape C budgets. J Geophys Res-Biogeo 2018;123:1302–17.
[39]Wang JF, Chen JG, Dallimore C, et al. Spatial distribution, fractions, and potential release of sediment phosphorus in the Hongfeng Reservoir,southwest China. Lake Reserv Manage 2015;31:214–24.
[40]Tao FX. Air-water CO2?ux in an algae bloom year for lake Fongfeng, southwest China:implications for the carbon cycle of global inland waters. Acta Geochim2017;36:658–66.
[41]Shi WQ, Chen QW, Yi QT, et al. Carbon emission from cascade reservoirs:spatial heterogeneity and mechanisms. Environ Sci Technol2017;51:12175–81.
[42]Donis D, Flury S, St?ckli A, et al. Full-scale evaluation of methane production under oxic conditions in a mesotrophic lake. Nat Commun 2017;8:1661.
[43]Bastviken D, Tranvik LJ, Downing JA, et al. Freshwater methane emissions offset the continental carbon sink. Science 2011;331:50.
[44]Abril G, Richard S. Gue′rin Fdr. In situ measurements of dissolved gases CO2and CH4in a wide range of concentrations in a tropical reservoir using an equilibrator. Sci Total Environ 2006;354:246–51.
[45]Fearnside PM. Greenhouse gas emissions from a hydroelectric reservoir(Brazil’s Tucurui dam)and the energy policy implications. Water Air Soil Poll 2002;133:69–96.
[46]Fearnside PM. Greenhouse gas emissions from hydroelectric dams:controversies provide a springboard for rethinking a supposedly ‘‘clean”energy source–an editorial comment. Clim Change 2004;66:1–8.
[47]Guerin F, Abril G, Richard S, et al. Methane and carbon dioxide emissions from tropical reservoirs:signi?cance of downstream rivers. Geophys Res Lett2006;33:L21407.
[48]Teodoru CR, Bastien J, Bonneville MC, et al. The net carbon footprint of a newly created boreal hydroelectric reservoir. Glob Biogeochem Cycles 2012;26:GB2016.
[49]Mendonca R, Kosten S, Sobek S, et al. Hydroelectric carbon sequestration. Nat Geosci 2012;5:838–40.
[50]Mendonca R, Muller RA, Clow D, et al. Organic carbon burial in global lakes and reservoirs. Nat Commun 2017;8:1694.
[2]Giles J. Methane quashes green credentials of hydropower. Nature2006;444:524–5.
[3]McCully P. Tropical hydropower is a signi?cant source of greenhouse gas emissions. A response to the International Hydropower. International Rivers Network; 2004.
[4]St Louis VL, Kelly CA, Duchemin E, et al. Reservoir surfaces as sources of greenhouse gases to the atmosphere:a global estimate. Bioscience2000;50:766–75.
[5]Steinhurst W. Hydropower greenhouse gas emissions. State of the research.Synapse Energy Economics Inc Report 2012.
[6]IHA. Hydro’s contribution, factsheet. London:International Hydropower Association7; 2010.
[7]Soumis N, Duchemin E, Canuel R, et al. Greenhouse gas emissions from reservoirs of the western United sSates. Glob Biogeochem Cycles 2004;18:GB3022.
[8]UNESCO/IHA. The UNESCO/IHA measurement speci?cation guidance for evaluating the GHG status of man-made freshwater reservoirs. Edition 1–June 2009.
[9]Raymond PA, Hartmann J, Lauerwald R, et al. Global carbon dioxide emissions from inland waters. Nature 2013;503:355–9.
[10]Dean WE, Gorham E. Magnitude and signi?cance of carbon burial in lakes,reservoirs, and peatlands. Geology 1998;26:535–8.
[11]Mendonca R, Kosten S, Sobek S, et al. Carbon sequestration in a large hydroelectric reservoir:an integrative seismic approach. Ecosystems2014;17:430–41.
[12]Jiang YB, Ji HB. Isotopic indicators of source and fate of particulate organic carbon in a karstic watershed on the Yunnan-Guizhou Plateau. Appl Geochem2013;36:153–67.
[13]Li J, Zhang L, Wu H, et al. Analysis of water quality evolution mechanism in the Maotiaohe watershed. Res Sci 2011;33:1481–8(In Chinese).
[14]Deng H, Xia P, Chen W, et al. Distribution characteristics of nutrient concentration in water–level?uctuating zone and sediment of Hongfeng Reservoir basin. J Wuhan Inst Tech 2014;36:27–33(in Chinese).
[15]Wang JF, Chen JG, Ding SM, et al. Effects of seasonal hypoxia on the release of phosphorus from sediments in deep-water ecosystem:a case study in Hongfeng Reservoir, southwest China. Environ Pollut 2016;219:858–65.
[16]Ye F, Zhang M, Liu H, et al. Analysis of organic enrichment in the sediment of red maple lake reservoir. Water Resources Protection 2010;26:8–12(In Chinese).
[17]Xu LB, Wu FC, Wan GJ, et al. Relationship between Pb-210(ex)activity and sedimentary organic carbon in sediments of 3 Chinese lakes. Environ Pollut2011;159:3462–7.
[18]Wang SL, Yeager KM, Wan GJ, et al. Carbon export and HCO3àfate in carbonate catchments:a case study in the karst plateau of southwestern China. Appl Geochem 2012;27:64–72.
[19]Lv M, Wang H, Cai Y, et al. Magnetic properties of core HF1-2 from lake Hongfeng in Guizhou Province and its implications for soil erosion. J Lake Sci2008;20:298–305(In Chinese).
[20]Wei ZQ, Liu CQ, Liang XB, et al. Degradation of organic matter in the sediments of Hongfeng Reservoir. Chin Sci Bull 2005;50:2377–80.
[21]Xiao HY, Liu CQ. Situation of sewage input re?ected by nitrogen isotopic composition in a sediment core of Hongfeng Lake. Chin Sci Bull2006;51:971–6.
[22]Wang Y. Biogeochemical processes of nutrients(P, N and C)at the sedimentwater interface in two reservoirs:Hongfeng hu and Baihua hu, Guizhou, China Doctor Dissertation. Guiyang:Institute of Geochemistry, Chinese Academy of Sciences; 2002.
[23]Wang F. The geochemical behavior of trace metals near water-sediments interface in seasonally anoxic lakes Doctor Dissertation. Beijing:University of Chinese Academy of Sciences; 2003.
[24]Zhang R, Wang L. Vertical distributions of phosphorus forms and bioavailable phosphorus in the sediments of houwu from Hongfeng Lake and calculation of environmental dredging depth. Earth Environ 2012;40:554–60(In Chinese).
[25]Wang FS, Wang B, Liu CQ, et al. Carbon dioxide emission from surface water in cascade reservoirs-river system on the Maotiao River, southwest of China.Atmos Environ 2011;45:3827–34.
[26]Yang Y. Impact on the production and emission of CH4and N2O of river by hydropower developmentàcase study on cascade reservoirs on the Maotiao River Master Thesis. Guiyang:Guizhou University; 2009.
[27]Yu SW, Wei YM, Guo HX, et al. Carbon emission coef?cient measurement of the coal-to-power energy chain in China. Appl Energ 2014;114:290–300.
[28]Encyclopedia of rivers and lakes in China:section of Changjiang River Basin.2010. China Water Power Press. Beijing
[29]Water Resources Department of Guizhou Province, China. Water Resources Bulletin 2011.
[30]Zhu YR, Zhang RY, Wu FC, et al. Phosphorus fractions and bioavailability in relation to particle size characteristics in sediments from Lake Hongfeng,southwest China. Environ Earth Sci 2013;68:1041–52.
[31]Qiu H, Su Y, Chen X, et al. Characteristics of the distributions of soil organic carbon and main components in a typical catchment in the karst plateau. J Agro-Environ Sci 2012;31:1956–64(In Chinese).
[32]Wang FS, Cao M, Wang BL, et al. Seasonal variation of CO2diffusion?ux from a large subtropical reservoir in east China. Atmos Environ 2015;103:129–37.
[33]Abril G, Guérin F, Richard S, et al. Carbon dioxide and methane emissions and the carbon budget of a 10-year old tropical reservoir(Petit Saut, French Guiana). Glob Biogeochem Cycles 2005;19:GB4007.
[34]Zhang W. The environmental characteristics and eutrophication of Hongfeng Lake and Baihu Lake. Guiyang:Guizhou Science and Technological Press; 1999.
[35]Liu ZH, Dreybrodt W. Signi?cance of the carbon sink produced by H2Ocarbonate-CO2-aquatic phototroph interaction on land. Sci Bull2015;60:182–91.
[36]Chen Y, Zhang S, Huang D, et al. The development of China’s yangtze river economic belt:How to make it in a green way? Sci Bull 2017;62:648–51.
[37]Cole JJ, Caraco NF. Carbon in catchments:connecting terrestrial carbon losses with aquatic metabolism. Mar Freshwater Res 2001;52:101–10.
[38]Lu WQ, Wang SL, Yeager KM, et al. Importance of considered organic versus inorganic source of carbon to lakes for calculating net effect on landscape C budgets. J Geophys Res-Biogeo 2018;123:1302–17.
[39]Wang JF, Chen JG, Dallimore C, et al. Spatial distribution, fractions, and potential release of sediment phosphorus in the Hongfeng Reservoir,southwest China. Lake Reserv Manage 2015;31:214–24.
[40]Tao FX. Air-water CO2?ux in an algae bloom year for lake Fongfeng, southwest China:implications for the carbon cycle of global inland waters. Acta Geochim2017;36:658–66.
[41]Shi WQ, Chen QW, Yi QT, et al. Carbon emission from cascade reservoirs:spatial heterogeneity and mechanisms. Environ Sci Technol2017;51:12175–81.
[42]Donis D, Flury S, St?ckli A, et al. Full-scale evaluation of methane production under oxic conditions in a mesotrophic lake. Nat Commun 2017;8:1661.
[43]Bastviken D, Tranvik LJ, Downing JA, et al. Freshwater methane emissions offset the continental carbon sink. Science 2011;331:50.
[44]Abril G, Richard S. Gue′rin Fdr. In situ measurements of dissolved gases CO2and CH4in a wide range of concentrations in a tropical reservoir using an equilibrator. Sci Total Environ 2006;354:246–51.
[45]Fearnside PM. Greenhouse gas emissions from a hydroelectric reservoir(Brazil’s Tucurui dam)and the energy policy implications. Water Air Soil Poll 2002;133:69–96.
[46]Fearnside PM. Greenhouse gas emissions from hydroelectric dams:controversies provide a springboard for rethinking a supposedly ‘‘clean”energy source–an editorial comment. Clim Change 2004;66:1–8.
[47]Guerin F, Abril G, Richard S, et al. Methane and carbon dioxide emissions from tropical reservoirs:signi?cance of downstream rivers. Geophys Res Lett2006;33:L21407.
[48]Teodoru CR, Bastien J, Bonneville MC, et al. The net carbon footprint of a newly created boreal hydroelectric reservoir. Glob Biogeochem Cycles 2012;26:GB2016.
[49]Mendonca R, Kosten S, Sobek S, et al. Hydroelectric carbon sequestration. Nat Geosci 2012;5:838–40.
[50]Mendonca R, Muller RA, Clow D, et al. Organic carbon burial in global lakes and reservoirs. Nat Commun 2017;8:1694.