气候变化领域集成服务门户(CCPortal): Large and seasonally varying biospheric CO2 fluxes in the Los Angeles megacity revealed by atmospheric radiocarbon

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DOI	10.1073/pnas.2005253117
	Large and seasonally varying biospheric CO2 fluxes in the Los Angeles megacity revealed by atmospheric radiocarbon
	Miller J.B.; Lehman S.J.; Verhulst K.R.; Miller C.E.; Duren R.M.; Yadav V.; Newman S.; Sloop C.D.
发表日期	2020
ISSN	0027-8424
起始页码	26681
结束页码	26687
卷号	117 期号:43
英文摘要	Measurements of Δ14C and CO2 can cleanly separate biogenic and fossil contributions to CO2 enhancements above background. Our measurements of these tracers in air around Los Angeles in 2015 reveal high values of fossil CO2 and a significant and seasonally varying contribution of CO2 from the urban biosphere. The biogenic CO2 is composed of sources such as biofuel combustion and human metabolism and an urban biospheric component likely originating from urban vegetation, including turf and trees. The urban biospheric component is a source in winter and a sink in summer, with an estimated amplitude of 4.3 parts per million (ppm), equivalent to 33% of the observed annual mean fossil fuel contribution of 13 ppm. While the timing of the net carbon sink is out of phase with wintertime rainfall and the sink seasonality of Southern California Mediterranean ecosystems (which show maximum uptake in spring), it is in phase with the seasonal cycle of urban water usage, suggesting that irrigated urban vegetation drives the biospheric signal we observe. Although 2015 was very dry, the biospheric seasonality we observe is similar to the 2006–2015 mean derived from an independent Δ14C record in the Los Angeles area, indicating that 2015 biospheric exchange was not highly anomalous. The presence of a large and seasonally varying biospheric signal even in the relatively dry climate of Los Angeles implies that atmospheric estimates of fossil fuel–CO2 emissions in other, potentially wetter, urban areas will be biased in the absence of reliable methods to separate fossil and biogenic CO2 © 2020 National Academy of Sciences. All rights reserved.
英文关键词	Carbon dioxide; Radiocarbon; Urban
语种	英语
scopus关键词	carbon; carbon dioxide; fossil fuel; California; carbon cycle; environmental monitoring; exhaust gas; human; procedures; season; Carbon Cycle; Carbon Dioxide; Carbon Isotopes; Environmental Monitoring; Fossil Fuels; Humans; Los Angeles; Seasons; Vehicle Emissions
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/160754
作者单位	Miller, J.B., National Oceanic and Atmospheric Administration Global Monitoring Laboratory, Boulder, CO 80305, United States; Lehman, S.J., Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, United States; Verhulst, K.R., Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, United States; Miller, C.E., Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, United States; Duren, R.M., Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, United States; Yadav, V., Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, United States; Newman, S., Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States; Sloop, C.D., Earth Networks, Germantown, MD 20876, United States
推荐引用方式 GB/T 7714	Miller J.B.,Lehman S.J.,Verhulst K.R.,et al. Large and seasonally varying biospheric CO2 fluxes in the Los Angeles megacity revealed by atmospheric radiocarbon[J],2020,117(43).
APA	Miller J.B..,Lehman S.J..,Verhulst K.R..,Miller C.E..,Duren R.M..,...&Sloop C.D..(2020).Large and seasonally varying biospheric CO2 fluxes in the Los Angeles megacity revealed by atmospheric radiocarbon.Proceedings of the National Academy of Sciences of the United States of America,117(43).
MLA	Miller J.B.,et al."Large and seasonally varying biospheric CO2 fluxes in the Los Angeles megacity revealed by atmospheric radiocarbon".Proceedings of the National Academy of Sciences of the United States of America 117.43(2020).