Dr. Benjamin Wolf

Research interests

Impact of agricultural production on Nitrogen and greenhouse gas budgets
Identification, characterization and source partitioning of N-cycle processes using stable isotope techniques
N₂O isotopomers
Process validation of biogeochemical models based on stable isotope measurements
Development and assessment of mitigation strategies using biogeochemical models

Projects involved

IBAN (Integrative Betrachtung von Stickstoff-Umsatzprozessen zur Optimierung der Stickstoffeffizienz)
Trace-N₂O: N₂O from the Swiss midlands: regional sources and hot spots
SUSALPS - Sustainable USe of ALPine and pre-alpine grassland Soils in a changing climate

Lectures

at Faculty of Forest and Environmental Sciences, Albert-Ludwigs University, Freiburg, Germany

Mikroorganismen in Biotechnologie und Umwelteinsatz (Bachelor)
Stoffkreisläufe in Ökosystemen (Bachelor / Master)

Email: benjamin.wolf@kit.edu
Telephone: +49 8821183 288

Publications List

2024

Gachibu Wangari, E.; Mwanake, R. M.; Houska, T.; Kraus, D.; Kikowatz, H.-M.; Wolf, B.; Gettel, G. M.; Breuer, L.; Ambus, P.; Kiese, R.; Butterbach-Bahl, K.
Spatial-temporal patterns of foliar and bulk soil

N isotopic signatures across a heterogeneous landscape: Linkages to soil N status, nitrate leaching, and N

O fluxes
2024. Soil Biology and Biochemistry, 199, 109609. doi:10.1016/j.soilbio.2024.109609

Subramaniam, L.; Engelsberger, F.; Wolf, B.; Brüggemann, N.; Philippot, L.; Dannenmann, M.; Butterbach-Bahl, K.
An innovative soil mesocosm system for studying the effect of soil moisture and background NO on soil surface C and N trace gas fluxes
2024. Biology and Fertility of Soils. doi:10.1007/s00374-024-01862-5

dos Reis Martins, M.; Ammann, C.; Boos, C.; Calanca, P.; Kiese, R.; Wolf, B.; Keel, S. G.
Reducing N fertilization in the framework of the European Farm to Fork strategy under global change: Impacts on yields, N₂O emissions and N leaching of temperate grasslands in the Alpine region
2024. Agricultural Systems, 219, Art.-Nr.: 104036. doi:10.1016/j.agsy.2024.104036

Dix, B. A.; Hauschild, M. E.; Niether, W.; Wolf, B.; Gattinger, A.
Regulating soil microclimate and greenhouse gas emissions with rye mulch in cabbage cultivation
2024. Agriculture, Ecosystems & Environment, 367, Art.-Nr.: 108951. doi:10.1016/j.agee.2024.108951

Yankelzon, I.; Schilling, L.; Butterbach-Bahl, K.; Gasche, R.; Han, J.; Hartl, L.; Kepp, J.; Matson, A.; Ostler, U.; Scheer, C.; Schneider, K.; Tenspolde, A.; Well, R.; Wolf, B.; Wrage-Moennig, N.; Dannenmann, M.
Lysimeter-based full fertilizer 15N balances corroborate direct dinitrogen emission measurements using the 15N gas flow method
2024. Biology and Fertility of Soils. doi:10.1007/s00374-024-01801-4

Garcia-Franco, N.; Wiesmeier, M.; Buness, V.; Berauer, B. J.; Schuchardt, M. A.; Jentsch, A.; Schlingmann, M.; Andrade-Linares, D.; Wolf, B.; Kiese, R.; Dannenmann, M.; Kögel-Knabner, I.
Rapid loss of organic carbon and soil structure in mountainous grassland topsoils induced by simulated climate change
2024. Geoderma, 442, Art.-Nr.: 116807. doi:10.1016/j.geoderma.2024.116807

Khan, F.; Franco-Luesma, S.; Dannenmann, M. U.; Gasche, R.; Gattinger, A.; Hartmann, F.; Tobisch, B.; Kiese, R.; Wolf, B.
Integrated rather than organic farming history facilitates soil nitrogen turnover and N

O reduction in a green rye – silage maize cropping sequence
2024. Biology and Fertility of Soils. doi:10.1007/s00374-024-01865-2

2023

Binacchi, F.; Niether, W.; Brock, C.; Knebl, L.; Brændholt, A.; Wolf, B.; Gattinger, A.
Demystifying the agronomic and environmental N performance of grain legumes across contrasting soil textures of central Germany
2023. Agriculture, Ecosystems and Environment, 356, Art.Nr.: 108645. doi:10.1016/j.agee.2023.108645

Wang, Y.; Yao, Z.; Wang, Y.; Yan, G.; Janz, B.; Wang, X.; Zhan, Y.; Wang, R.; Zheng, X.; Zhou, M.; Zhu, B.; Kiese, R.; Wolf, B.; Butterbach-Bahl, K.
Characteristics of annual NH

emissions from a conventional vegetable field under various nitrogen management strategies
2023. Journal of Environmental Management, 342, Artkl.Nr.: 118276. doi:10.1016/j.jenvman.2023.118276

2022

Schreiber, M.; Bazaios, E.; Ströbel, B.; Wolf, B.; Ostler, U.; Gasche, R.; Schlingmann, M.; Kiese, R.; Dannenmann, M.
Impacts of slurry acidification and injection on fertilizer nitrogen fates in grassland
2022. Nutrient Cycling in Agroecosystems, 125 (2), 171–186. doi:10.1007/s10705-022-10239-9

Barthel, M.; Bauters, M.; Baumgartner, S.; Drake, T. W.; Bey, N. M.; Bush, G.; Boeckx, P.; Botefa, C. I.; Dériaz, N.; Ekamba, G. L.; Gallarotti, N.; Mbayu, F. M.; Mugula, J. K.; Makelele, I. A.; Mbongo, C. E.; Mohn, J.; Mandea, J. Z.; Mpambi, D. M.; Ntaboba, L. C.; Rukeza, M. B.; Spencer, R. G. M.; Summerauer, L.; Vanlauwe, B.; Van Oost, K.; Wolf, B.; Six, J.
Low N

O and variable CH

fluxes from tropical forest soils of the Congo Basin
2022. Nature Communications, 13 (1), Art.-Nr.: 330. doi:10.1038/s41467-022-27978-6

Wolz, K.; Leitner, S.; Merbold, L.; Wolf, B.; Mauder, M.
Enteric methane emission estimates for Kenyan cattle in a nighttime enclosure using a backward Lagrangian Stochastic dispersion technique
2022. Theoretical and Applied Climatology, 147, 1091–1103. doi:10.1007/s00704-021-03868-7

2021

Zhu, Y.; Merbold, L.; Leitner, S.; Wolf, B.; Pelster, D.; Goopy, J.; Butterbach-Bahl, K.
Interactive effects of dung deposited onto urine patches on greenhouse gas fluxes from tropical pastures in Kenya
2021. The science of the total environment, 761, Art.-Nr.: 143184. doi:10.1016/j.scitotenv.2020.143184

Merbold, L.; Decock, C.; Eugster, W.; Fuchs, K.; Wolf, B.; Buchmann, N.; Hörtnagl, L.
Are there memory effects on greenhouse gas emissions (CO

, N

O and CH

) following grassland restoration?
2021. Biogeosciences, 18 (4), 1481–1498. doi:10.5194/bg-18-1481-2021

Malique, F.; Wangari, E.; Andrade-Linares, D. R.; Schloter, M.; Wolf, B.; Dannenmann, M.; Schulz, S.; Butterbach-Bahl, K.
Effects of slurry acidification on soil N

O fluxes and denitrification
2021. Journal of Plant Nutrition and Soil Science, 184 (6), 696–708. doi:10.1002/jpln.202100095

2020

Schlingmann, M.; Tobler, U.; Berauer, B.; Garcia-Franco, N.; Wilfahrt, P.; Wiesmeier, M.; Jentsch, A.; Wolf, B.; Kiese, R.; Dannenmann, M.
Intensive slurry management and climate change promote nitrogen mining from organic matter-rich montane grassland soils
2020. Plant and soil, 456, 81–98. doi:10.1007/s11104-020-04697-9

Clough, T. J.; Cardenas, L. M.; Friedl, J.; Wolf, B.
Nitrous oxide emissions from ruminant urine: science and mitigation for intensively managed perennial pastures
2020. Current opinion in environmental sustainability, 47, 21–27. doi:10.1016/j.cosust.2020.07.001

Ibraim, E.; Denk, T.; Wolf, B.; Barthel, M.; Gasche, R.; Wanek, W.; Zhang, S.; Kiese, R.; Butterbach-Bahl, K.; Eggleston, S.; Emmenegger, L.; Six, J.; Mohn, J.
Denitrification Is the Main Nitrous Oxide Source Process in Grassland Soils According to Quasi-Continuous Isotopocule Analysis and Biogeochemical Modeling
2020. Global biogeochemical cycles, 34 (6). doi:10.1029/2019GB006505

Harris, S. J.; Liisberg, J.; Xia, L.; Wei, J.; Zeyer, K.; Yu, L.; Barthel, M.; Wolf, B.; Kelly, B. F. J.; Cendón, D. I.; Blunier, T.; Six, J.; Mohn, J.
N

O isotopocule measurements using laser spectroscopy: analyzer characterization and intercomparison
2020. Atmospheric measurement techniques, 13 (5), 2797–2831. doi:10.5194/amt-13-2797-2020

Wu, X.; Chen, Z.; Kiese, R.; Fu, J.; Gschwendter, S.; Schloter, M.; Liu, C.; Butterbach-Bahl, K.; Wolf, B.; Dannenmann, M.
Dinitrogen (N

) pulse emissions during freeze-thaw cycles from montane grassland soil
2020. Biology and fertility of soils, 56, 959–972. doi:10.1007/s00374-020-01476-7

Kunz, M.; Lavric, J. V.; Gasche, R.; Gerbig, C.; Grant, R. H.; Koch, F.-T.; Schumacher, M.; Wolf, B.; Zeeman, M.
Surface flux estimates derived from UAS-based mole fraction measurements by means of a nocturnal boundary layer budget approach
2020. Atmospheric measurement techniques, 13 (4), 1671–1692. doi:10.5194/amt-13-1671-2020

2019

Chen, W.; Zheng, X.; Wolf, B.; Yao, Z.; Liu, C.; Butterbach-Bahl, K.; Brüggemann, N.
Long-term grazing effects on soil-atmosphere exchanges of CO2, CH4 and N2O at different grasslands in Inner Mongolia: A soil core study
2019. Ecological indicators, 105, 316–328. doi:10.1016/j.ecolind.2017.09.035

Xia, L.; Li, X.; Ma, Q.; Lam, S. K.; Wolf, B.; Kiese, R.; Butterbach-Bahl, K.; Chen, D.; Li, Z.; Yan, X.
Simultaneous quantification of N2, NH3 and N2O emissions from a flooded paddy field under different N fertilization regimes
2019. Global change biology. doi:10.1111/gcb.14958

Ibraim, E.; Wolf, B.; Harris, E.; Gasche, R.; Wei, J.; Yu, L.; Kiese, R.; Eggleston, S.; Butterbach-Bahl, K.; Zeeman, M.; Tuzson, B.; Emmenegger, L.; Six, J.; Henne, S.; Mohn, J.
Attribution of N₂O sources in a grassland soil with laser spectroscopy based isotopocule analysis
2019. Biogeosciences, 16 (16), 3247–3266. doi:10.5194/bg-16-3247-2019

Denk, T. R. A.; Kraus, D.; Kiese, R.; Butterbach-Bahl, K.; Wolf, B.
Constraining N cycling in the ecosystem model LandscapeDNDC with the stable isotope model SIMONE
2019. Ecology, 100 (5), Art. Nr.: e02675. doi:10.1002/ecy.2675

2018

Xia, L.; Lam, S. K.; Wolf, B.; Kiese, R.; Chen, D.; Butterbach-Bahl, K.
Trade-offs between soil carbon sequestration and reactive nitrogen losses under straw return in global agroecosystems
2018. Global change biology, 24 (12), 5919–5932. doi:10.1111/gcb.14466

Harris, E.; Ladreiter-Knauss, T.; Butterbach-Bahl, K.; Wolf, B.; Bahn, M.
Land-use and abandonment alters methane and nitrous oxide fluxes in mountain grasslands
2018. The science of the total environment, 628-629, 997–1008. doi:10.1016/j.scitotenv.2018.02.119

Kiese, R.; Fersch, B.; Baessler, C.; Brosy, C.; Butterbach-Bahl, K.; Chwala, C.; Dannenmann, M.; Fu, J.; Gasche, R.; Grote, R.; Jahn, C.; Klatt, J.; Kunstmann, H.; Mauder, M.; Rödiger, T.; Smiatek, G.; Soltani, M.; Steinbrecher, R.; Völksch, I.; Werhahn, J.; Wolf, B.; Zeeman, M.; Schmid, H. P.
The TERENO pre-alpine observatory: Integrating meteorological, hydrological, and biogeochemical measurements and modeling
2018. Vadose zone journal, 17 (1), Art. Nr.: 180060. doi:10.2136/vzj2018.03.0060

2017

Wolf, B.; Chwala, C.; Fersch, B.; Garvelmann, J.; Junkermann, W.; Zeeman, M. J.; Angerer, A.; Adler, B.; Beck, C.; Brosy, C.; Brugger, P.; Emeis, S.; Dannenmann, M.; De Roo, F.; Diaz-Pines, E.; Haas, E.; agen, M.; Hajnsek, I.; Jacobeit, J.; Jagdhuber, T.; Kalthoff, N.; Kiese, R.; Kunstmann, H.; Kosak, O.; Krieg, R.; Malchow, C.; Mauder, M.; Merz, R.; Notarnicola, C.; Philipp, A.; Reif, W.; Reineke, S.; Rödiger, S.; Ruehr, N.; Schäfer, K.; Schrön, M.; Senatore, A.; Shupe, H.; Völksch, I.; Wanninger, C.; Zacharias, S.; Schmid, H. P.
The ScaleX campaign: scale-crossing land-surface and boundary layer processes in the TERENO-preAlpine observatory
2017. Bulletin of the American Meteorological Society, 98 (6), 1217–1234. doi:10.1175/BAMS-D-15-00277.1

Chen, W.; Zheng, X.; Wolf, B.; Yao, Z.; Liu, C.; Butterbach-Bahl, K.
The Potential of Soil Carbon Dioxide, Methane and Nitrous Oxide Exchanges of Differently Grazed Semiarid Steppes : Based on Soil Core Experiment
2017. Fresenius environmental bulletin, 26 (4), 2571–2581

Butterbach-Bahl, K.; Wolf, B.
Greenhouse gases: Warming from freezing soils
2017. Nature geoscience, 10 (4), 248–249. doi:10.1038/ngeo2915

Brosy, C.; Krampf, K.; Zeeman, M.; Wolf, B.; Junkermann, W.; Schäfer, K.; Emeis, S.; Kunstmann, H.
Simultaneous multicopter-based air sampling and sensing of meteorological variables
2017. Atmospheric measurement techniques, 10 (8), 2773–2784. doi:10.5194/amt-10-2773-2017

Golston, L. M.; Tao, L.; Brosy, C.; Schäfer, K.; Wolf, B.; McSpiritt, J.; Buchholz, B.; Caulton, D. R.; Pan, D.; Zondlo, M. A.; Yoel, D.; Kunstmann, H.; McGregor, M.
Lightweight mid-infrared methane sensor for unmanned aerial systems
2017. Applied physics / B, 123 (6), 170. doi:10.1007/s00340-017-6735-6

Denk, T. R. A.; Mohn, J.; Decock, C.; Lewicka-Szczebak, D.; Harris, E.; Butterbach-Bahl, K.; Kiese, R.; Wolf, B.
The nitrogen cycle: A review of isotope effects and isotope modeling approaches
2017. Soil biology & biochemistry, 105, 121–137. doi:10.1016/j.soilbio.2016.11.015

Díaz-Pinés, E.; Molina-Herrera, S.; Dannenmann, M.; Braun, J.; Haas, E.; Willibald, G.; Arias-Navarro, C.; Grote, R.; Wolf, B.; Saiz, G.; Aust, C.; Schnitzler, J.-P.; Butterbach-Bahl, K.
Nitrate leaching and soil nitrous oxide emissions diminish with time in a hybrid poplar short-rotation coppice in southern Germany
2017. Global change biology / Bioenergy, 9 (3), 613–626. doi:10.1111/gcbb.12367

2016

Wen, Y.; Chen, Z.; Dannenmann, M.; Carminati, A.; Willibald, G.; Kiese, R.; Wolf, B.; Veldkamp, E.; Butterbach-Bahl, K.; Corre, M. D.
Disentangling gross N₂O production and consumption in soil
2016. Scientific reports, 6, Art. Nr. 36517. doi:10.1038/srep36517

2015

Wolf, B.; Merbold, L.; Decock, C.; Tuzson, B.; Harris, E.; Six, J.; Emmenegger, L.; Mohn, J.
First on-line isotopic characterization of N₂O above intensively managed grassland
2015. Biogeosciences, 12 (8), 2517–2531. doi:10.5194/bg-12-2517-2015

Harris, E.; Joss, A.; Emmenegger, L.; Kipf, M.; Wolf, B.; Mohn, J.; Wunderlin, P.
Isotopic evidence for nitrous oxide production pathways in a partial nitritation-anammox reactor
2015. Water research, 83, 258–270. doi:10.1016/j.watres.2015.06.040

Barton, L.; Wolf, B.; Rowlings, D.; Scheer, C.; Kiese, R.; Grace, P.; Stefanova, K.; Butterbach-Bahl, K.
Sampling frequency affects estimates of annual nitrous oxide fluxes
2015. Scientific reports, 5, 15912. doi:10.1038/srep15912

2014

Mohn, J.; Wolf, B.; Toyoda, S.; Lin, C. T.; Liang, M. C.; Brüggemann, N.; Wissel, H.; Steiker, A. E.; Dyckmans, J.; Szwec, L.; Ostrom, N. E.; Casciotti, K. L.; Forbes, M.; Giesemann, A.; Well, R.; Doucett, R. R.; Yarnes, C. T.; Ridley, A. R.; Kaiser, J.; Yoshida, N.
Interlaboratory assessment of nitrous oxide isotopomer analysis by isotope ratio mass spectrometry and laser spectrometry: current status and perspectives
2014. Rapid communications in mass spectrometry, 28, 1995–2007. doi:10.1002/rcm.6982

2013

Pihlatie, M. K.; Christiansen, J. R.; Aaltonen, H.; Korhonen, J. F. J.; Nordbo, A.; Rasilo, T.; Benanti, G.; Giebels, M.; Helmy, M.; Sheehy, J.; Jones, S.; Juszczak, R.; Klefoth, R.; Lobo-do-Vale, R.; Rosa, A. P.; Schreiber, P.; Serça, D.; Vicca, S.; Wolf, B.; Pumpanen, J.
Comparison of static chambers to measure CH₄ emissions from soils
2013. Agricultural and forest meteorology, 171-172, 124–136. doi:10.1016/j.agrformet.2012.11.008

Chen, W.; Wolf, B.; Zheng, X.; Yao, Z.; Butterbach-Bahl, K.; Brüggemann, N.; Han, S.; Liu, C.; Han, X.
Carbon dioxide emission from temperate semiarid steppe during the non-growing season
2013. Atmospheric Environment, 64, 141–149. doi:10.1016/j.atmosenv.2012.10.004

Chen, W.; Zheng, X.; Chen, Q.; Wolf, B.; Butterbach-Bahl, K.; Brüggemann, N.; Lin, S.
Effects of increasing precipitation and nitrogen deposition on CH₄ and N₂O fluxes and ecosystem respiration in a degraded steppe in Inner Mongolia, China
2013. Geoderma, 192, 335–340. doi:10.1016/j.geoderma.2012.08.018

Luo, G. J.; Kiese, R.; Wolf, B.; Butterbach-Bahl, K.
Effects of soil temperature and moisture on methane uptakes and nitrous oxide emissions across three different ecosystem types
2013. Biogeosciences discussions, 10 (1), 927–965. doi:10.5194/bgd-10-927-2013

Luo, G. J.; Kiese, R.; Wolf, B.; Butterbach-Bahl, K.
Effects of soil temperature and moisture on methane uptake and nitrous oxide emissions across three different ecosystem types
2013. Biogeosciences, 10, 3205–3219. doi:10.5194/bg-10-3205-2013

2012

Schönbach, P.; Wolf, B.; Dickhöfer, U.; Wiesmeier, M.; Chen, W.; Wan, H.; Gierus, M.; Butterbach-Bahl, K.; Kögel-Knabner, I.; Susenbeth, A.; Zheng, X.; Taube, F.
Grazing effects on the greenhouse gas balance of a temperate steppe ecosystem
2012. Nutrient Cycling in Agroecosystems, 93, 357–371. doi:10.1007/s10705-012-9521-1

Wu, H.; Dannenmann, M.; Wolf, B.; Han, X. G.; Zheng, X.; Butterbach-Bahl, K.
Seasonality of soil microbial nitrogen turnover in continental steppe soils of Inner Mongolia
2012. Ecosphere, Artcle 34, 3. doi:10.1890/ES11-00188.1

Luo, G. J.; Brüggemann, N.; Wolf, B.; Gasche, R.; Grote, R.; Butterbach-Bahl, K.
Decadal variability of soil CO₂, NO, N₂O, and CH₄ fluxes at the Höglwald Forest, Germany
2012. Biogeosciences, 9, 1741–1763. doi:10.5194/bg-9-1741-2012

Wolf, B.; Kiese, R.; Chen, W.; Grote, R.; Zheng, X.; Butterbach-Bahl, K.
Modeling N₂O emissions from steppe in Inner Mongolia, China, with consideration of spring thaw and grazing intensity
2012. Plant and Soil, 350, 297–310. doi:10.1007/s11104-011-0908-6

2011

Chen, W.; Wolf, B.; Brüggemann, N.; Butterbach-Bahl, K.; Zheng, X.
Annual emissions of greenhouse gases from sheepfolds in Inner Mongolia
2011. Plant and Soil, 340, 291–301. doi:10.1007/s11104-010-0367-5

Chen, W.; Wolf, B.; Zheng, X.; Yao, Z.; Butterbach-Bahl, K.; Brüggemann, N.; Liu, C.; Han, S.; Han, X.
Annual methane uptake by temperate semiarid steppes as regulated by stocking rates, aboveground plant biomass and topsoil air permeability
2011. Global Change Biology, 17, 2803–2816. doi:10.1111/j.1365-2486.2011.02444.x

2010

Yao, Z.; Wu, X.; Wolf, B.; Dannenmann, M.; Butterbach-Bahl, K.; Brüggemann, N.; Chen, W.; Zheng, X.
Soil-atmosphere exchange potential of NO and N₂O in different land use types of Inner Mongolia as affected by soil temperature, soil moisture, freeze-thaw, and drying-wetting events
2010. Journal of geophysical research, 115, D17116. doi:10.1029/2009JD013528

Yao, Z.; Wolf, B.; Chen, W.; Butterbach-Bahl, K.; Brüggemann, N.; Wiesmeier, M.; Dannenmann, M.; Blank, B.; Zheng, X.
Spatial variability of N₂O, CH₄ and CO₂ fluxes within the Xilin River catchment of Inner Mongolia, China: a soil core study
2010. Plant and Soil, 331, 341–359. doi:10.1007/s11104-009-0257-x

Wu, X.; Yao, Z.; Brüggemann, N.; Shen, Z. Y.; Wolf, B.; Dannenmann, M.; Zheng, X.; Butterbach-Bahl, K.
Effects of soil moisture and temperature on CO₂ and CH₄ soil-atmosphere exchange of various land use/cover types in a semi-arid grassland in Inner Mongolia, China
2010. Soil Biology and Biochemistry, 42, 773–787. doi:10.1016/j.soilbio.2010.01.013

Chen, W.; Wolf, B.; Yao, Z.; Brüggemann, N.; Butterbach-Bahl, K.; Liu, C.; Han, S.; Han, X.; Zheng, X.
Annual methane uptake by typical semiarid steppe in Inner Mongolia
2010. Journal of geophysical research, 115, D15108. doi:10.1029/2009JD013783

Wu, X.; Brüggemann, N.; Gasche, R.; Shen, Z.; Wolf, B.; Butterbach-Bahl, K.
Environmental controls over soil-atmosphere exchange of N₂O, NO, and CO₂ in a temperate Norway spruce forest
2010. Global biogeochemical cycles, 24 (2), GB2012. doi:10.1029/2009GB003616

Wolf, B.; Zheng, X.; Brüggemann, N.; Chen, W.; Dannenmann, M.; Han, X.; Sutton, M. A.; Wu, H.; Yao, Z.; Butterbach-Bahl, K.
Grazing-induced reduction of natural nitrous oxide release from continental steppe
2010. Nature <London>, 464 (7290), 881–84. doi:10.1038/nature08931