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Your search keyword '"Spencer, R.G.M."' showing total 11 results
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11 results on '"Spencer, R.G.M."'

1. How humans alter dissolved organic matter composition in freshwater: relevance for the Earth’s biogeochemistry

Author

Xenopoulos, M.A., Barnes, R.T., Boodoo, K.S., Butman, D., Catalán, N., D’Amario, S.C., Fasching, Christina, Kothawala, D.N., Pisani, O., Solomon, C.T., Spencer, R.G.M., Williams, C.J., Wilson, H.F., Xenopoulos, M.A., Barnes, R.T., Boodoo, K.S., Butman, D., Catalán, N., D’Amario, S.C., Fasching, Christina, Kothawala, D.N., Pisani, O., Solomon, C.T., Spencer, R.G.M., Williams, C.J., and Wilson, H.F.

Abstract

Dissolved organic matter (DOM) is recognized for its importance in freshwater ecosystems, but historical reliance on DOM quantity rather than indicators of DOM composition has led to an incomplete understanding of DOM and an underestimation of its role and importance in biogeochemical processes. A single sample of DOM can be composed of tens of thousands of distinct molecules. Each of these unique DOM molecules has their own chemical properties and reactivity or role in the environment. Human activities can modify DOM composition and recent research has uncovered distinct DOM pools laced with human markers and footprints. Here we review how land use change, climate change, nutrient pollution, browning, wildfires, and dams can change DOM composition which in turn will affect internal processing of freshwater DOM. We then describe how human-modified DOM can affect biogeochemical processes. Drought, wildfires, cultivated land use, eutrophication, climate change driven permafrost thaw, and other human stressors can shift the composition of DOM in freshwater ecosystems increasing the relative contribution of microbial-like and aliphatic components. In contrast, increases in precipitation may shift DOM towards more relatively humic-rich, allochthonous forms of DOM. These shifts in DOM pools will likely have highly contrasting effects on carbon outgassing and burial, nutrient cycles, ecosystem metabolism, metal toxicity, and the treatments needed to produce clean drinking water. A deeper understanding of the links between the chemical properties of DOM and biogeochemical dynamics can help to address important future environmental issues, such as the transfer of organic contaminants through food webs, alterations to nitrogen cycling, impacts on drinking water quality, and biogeochemical effects of global climate change.

Published
2021

2. Interlaboratory comparison of humic substances compositional space as measured by Fourier transform ion cyclotron resonance mass spectrometry (IUPAC Technical Report)

Author

Zherebker, A., Kim, S., Schmitt-Kopplin, P., Spencer, R.G.M., Lechtenfeld, Oliver, Podgorski, D.C., Hertkorn, N., Harir, M., Nurfajin, N., Koch, B., Nikolaev, E.N., Shirshin, E.A., Berezin, S.A., Kats, D.S., Rukhovich, G.D., Perminova, I.V., Zherebker, A., Kim, S., Schmitt-Kopplin, P., Spencer, R.G.M., Lechtenfeld, Oliver, Podgorski, D.C., Hertkorn, N., Harir, M., Nurfajin, N., Koch, B., Nikolaev, E.N., Shirshin, E.A., Berezin, S.A., Kats, D.S., Rukhovich, G.D., and Perminova, I.V.

Abstract

Interlaboratory comparison on the determination of the molecular composition of humic substances (HS) was undertaken in the framework of IUPAC project 2016-015-2-600. The analysis was conducted using high resolution mass spectrometry, nominally, Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) with electrospray ionization. Six samples of HS from freshwater, soil, and leonardite were used for this study, including one sample of humic acids (HA) from coal (leonardite), two samples of soil HA (the sod-podzolic soil and chernozem), two samples of soil fulvic acids (FA) (the sod-podzolic soil and chernozem), and one sample of freshwater humic acids (the Suwannee River). The samples were analyzed on five different FTICR MS instruments using the routine conditions applied in each participating laboratory. The results were collected as mass lists, which were further assigned formulae for the determination of molecular composition. The similarity of the obtained data was evaluated using appropriate statistical metrics. The results have shown that direct comparison of discrete stoichiometries assigned to the mass lists obtained by the different laboratories yielded poor results with low values of the Jaccard similarity score – not exceeding 0.56 (not more than 56 % of the similar peaks). The least similarity was observed for the aromatics-rich HA samples from leonardite (coal) and the chernozem soil, which might be connected to difficulties in their ionization. The reliable similarity among the data obtained in this intercomparison study was achieved only by transforming a singular point (stoichiometry) in van Krevelen diagram into a sizeable pixel (a number of closely located stoichiometries), which can be calculated from the population density distribution. The conclusion was made that, so far, these are descriptors of occupation density distribution, which provide the metrics compliant with the data quality requirements, such as the reproducibility of

Published
2020

3. State of the climate in 2018

Author

Ades, M., Adler, R., Aldeco, L.S., Alejandra, G., Alfaro, E.J., Aliaga-Nestares, V., Allan, R.P., Allan, R., Alves, L.M., Amador, J.A., Andersen, J.K., Anderson, J., Arndt, D.S., Arosio, C., Arrigo, K., Azorin-Molina, C., Bardin, M.Y., Barichivich, J., Barreira, S., Baxter, S., Beck, H.E., Becker, A., Bell, G.D., Bellouin, N., Belmont, M., Benedetti, A., Benedict, I., Bernhard, G.H., Berrisford, P., Berry, D.I., Bettio, L., Bhatt, U.S., Biskaborn, B.K., Bissolli, P., Bjella, K.L., Bjerke, J.K., Blake, E.S., Blenkinsop, S., Blunden, J., Bock, O., Bosilovich, M.G., Boucher, O., Box, J.E., Boyer, T., Braathen, G., Bringas, F.G., Bromwich, D.H., Brown, A., Brown, R., Brown, T.J., Buehler, S.A., Cáceres, L., Calderón, B., Camargo, S.J., Campbell, J.D., Campos Diaz, D.A., Cappelen, J., Carrea, L., Carrier, S.B., Carter, B.R., Castro, A.Y., Cetinic, I., Chambers, D.P., Chen, L., Cheng, L., Cheng, V.Y.S., Christiansen, H.H., Christy, J.R., Chung, E.-S., Claus, F., Clem, K.R., Coelho, C.A.S., Coldewey-Egbers, M., Colwell, S., Cooper, O.R., Cosca, C., Covey, C., Coy, L., Dávila, C.P., Davis, S.M., de Eyto, E., de Jeu, R.A.M., De Laat, J., Decharme, B., Degasperi, C.L., Degenstein, D., Demircan, M., Derksen, C., Dhurmea, K.R., Di Girolamo, L., Diamond, H.J., Diaz, E., Diniz, F.A., Dlugokencky, E.J., Dohan, K., Dokulil, M.T., Dolman, A.J., Domingues, C.M., Domingues, R., Donat, M.G., Dorigo, W.A., Drozdov, D.S., Druckenmiller, M.L., Dunn, R.J.H., Durre, I., Dutton, G.S., Elkharrim, M., Elkins, J.W., Epstein, H.E., Espinoza, J.C., Famiglietti, J.S., Farrell, S.L., Fausto, R.S., Feely, R.A., Feng, Z., Fenimore, C., Fettweis, X., Fioletov, V.E., Flemming, J., Fogt, R.L., Forbes, B.C., Foster, M.J., Francis, S.D., Franz, B.A., Frey, R.A., Frith, S.M., Froidevaux, L., Ganter, C., Garforth, J., Gerland, S., Gilson, J., Gleason, K., Gobron, N., Goetz, S., Goldenberg, S.B., Goni, G., Gray, A., Groo, J.-U., Gruber, A., Gu, G., Guard, C.C.P., Gupta, S.K., Gutiérrez, D., Haas, Christian, Hagos, S., Hahn, S., Haimberger, L., Hall, B.D., Halpert, M.S., Hamlington, B.D., Hanna, E., Hanssen-Bauer, I., Harris, I., Hazeleger, W., He, Q., Heidinger, A.K., Heim, Jr., Hemming, D.L., Hendricks, Stefan, Hernández, R., Hersbach, H.E., Hidalgo, H.G., Ho, S.-P.B., Holmes, R.M., Hu, C., Huang, B., Hubbard, K., Hubert, D., Hurst, D.F., Ialongo, I., Ijampy, J.A., Inness, A., Isaac, V., Isaksen, K., Ishii, M., Jeffries, M.O., Jevrejeva, S., Jia, G., Jiménez, C., Jin, X., John, V., Johnsen, B., Johnson, G.C., Johnson, K.S., Johnson, B., Jones, P.D., Jumaux, G., Kabidi, K., Kaiser, J.W., Karaköylü, E.M., Karlsen, S.-R., Karnauskas, M., Kato, S., Kazemi, A.F., Kelble, C., Keller, L.M., Kennedy, J., Kholodov, A.L., Khoshkam, M., Kidd, R., Killick, R., Kim, H., Kim, S.-J., King, A.D., King, B.A., Kipling, Z., Klotzbach, P.J., Knaff, J.A., Korhonen, J., Korshunova, N.N., Kramarova, N.A., Kratz, D.P., Kruger, A., Kruk, M.C., Krumpen, Thomas, Labbé, L., Ladd, C., Lakatos, M., Lakkala, K., Lander, M.A., Landschützer, P., Landsea, C.W., Lareau, N.P., Lavado-Casimiro, W., Lazzara, M.A., Lee, T.C., Leuliette, E., L�heureux, M., Li, B., Li, T., Lieser, J.L., Lim, J.-Y., Lin, I.-I., Liu, H., Locarnini, R., Loeb, N.G., Long, C.S., López, L.A., Lorrey, A.M., Loyola, D., Lumpkin, R., Luo, J.-J., Luojus, K., Lyman, J.M., Malkova, G.V., Manney, G.L., Marchenko, S.S., Marengo, J.A., Marin, D., Marquardt Collow, A.B., Marra, J.J., Marszelewski, W., Martens, B., Martínez-Güingla, R., Massom, R.A., May, L., Mayer, M., Mazloff, M., McBride, C., McCabe, M., McClelland, J.W., McEvoy, D.J., McGree, S., McVicar, T.R., Mears, C.A., Meier, W., Meijers, A., Mekonnen, A., Mengistu Tsidu, G., Menzel, W.P., Merchant, C.J., Meredith, M.P., Merrifield, M.A., Miller, B., Miralles, D.G., Misevicius, N., Mitchum, G.T., Mochizuki, Y., Monselesan, D., Montzka, S.A., Mora, N., Morice, C., Mosquera-Vásquez, K., Mostafa, A.E., Mote, T., Mudryk, L., Mühle, J., Mullan, A.B., Müller, R., Myneni, R., Nash, E.R., Nauslar, N.J., Nerem, R.S., Newman, P.A., Nicolas, J.P., Nieto, J.J., Noetzli, J., Osborn, T.J., Osborne, E., Overland, J., Oyunjargal, L., Park, T., Pasch, R.J., Pascual Ramírez, R., Pastor Saavedra, M.A., Paterson, A.M., Pearce, P.R., Pelto, M.S., Perovich, D., Petropavlovskikh, I., Pezza, A.B., Phillips, C., Phillips, D., Phoenix, G., Pinty, B., Pitts, M., Po-Chedley, S., Polashenski, C., Preimesberger, W., Purkey, S.G., Quispe, N., Rajeevan, M., Rakotoarimalala, C.L., Ramos, A.M., Ramos, I., Randel, W., Raynolds, M.K., Reagan, J., Reid, P., Reimer, C., Rémy, S., Revadekar, J.V., Richardson, A.D., Richter-Menge, J., Ricker, Robert, Ripaldi, A., Robinson, D.A., Rodell, M., Rodriguez Camino, E., Romanovsky, V.E., Ronchail, J., Rosenlof, K.H., Rösner, B., Roth, C., Rozanov, A., Rusak, J.A., Rustemeier, E., Rutishäuser, T., Sallée, J.-B., Sánchez-Lugo, A., Santee, M.L., Sawaengphokhai, P., Sayouri, A., Scambos, T.A., Scanlon, T., Scardilli, A.S., Schenzinger, V., Schladow, S.G., Schmid, C., Schmid, M., Schoeneich, P., Schreck, III, Selkirk, H.B., Sensoy, S., Shi, L., Shiklomanov, A.I., Shiklomanov, N.I., Shimpo, A., Shuman, C.A., Siegel, D.A., Sima, F., Simmons, A.J., Smeets, C.J.P.P., Smith, A., Smith, S.L., Soden, B., Sofieva, V., Sparks, T.H., Spence, J., Spencer, R.G.M., Spillane, S., Srivastava, A.K., Stabeno, P.J., Stackhouse, Jr., Stammerjohn, S., Stanitski, D.M., Steinbrecht, W., Stella, J.L., Stengel, M., Stephenson, T.S., Strahan, S.E., Streeter, C., Streletskiy, D.A., Sun-Mack, S., Suslova, A., Sutton, A.J., Swart, S., Sweet, W., Takahashi, K.S., Tank, S.E., Taylor, M.A., Tedesco, M., Thackeray, S.J., Thompson, P.R., Timbal, B., Timmermans, M.-L., Tobin, S., Tømmervik, H., Tourpali, K., Trachte, K., Tretiakov, M., Trewin, B.C., Triñanes, J.A., Trotman, A.R., Tschudi, M., Tye, M.R., van As, D., van de Wal, R.S.W., van der A, R.J., van der Schalie, R., van der Schrier, G., van der Werf, G.R., van Heerwaarden, C., Van Meerbeeck, C.J., Verburg, P., Vieira, G., Vincent, L.A., Vömel, H., Vose, R.S., Walker, D.A., Walsh, J.E., Wang, B., Wang, H., Wang, L., Wang, M., Wang, R., Wang, S.-H., Wanninkhof, R., Watanabe, S., Weber, M., Webster, M., Weerts, A., Weller, R.A., Westberry, T.K., Weyhenmeyer, G.A., Widlansky, M.J., Wijffels, S.E., Wilber, A.C., Wild, J.D., Willett, K.M., Wong, T., Wood, E.F., Woolway, R.I., Xue, Y., Yin, X., Yu, L., Zambrano, E., Zeyaeyan, S., Zhang, H.-M., Zhang, P., Zhao, G., Zhao, L., Zhou, X., Zhu, Z., Ziemke, J.R., Ziese, M., Andersen, A., Griffin, J., Hammer, G., Love-Brotak, S.E., Misch, D.J., Riddle, D.B., Veasey, S.W., Ades, M., Adler, R., Aldeco, L.S., Alejandra, G., Alfaro, E.J., Aliaga-Nestares, V., Allan, R.P., Allan, R., Alves, L.M., Amador, J.A., Andersen, J.K., Anderson, J., Arndt, D.S., Arosio, C., Arrigo, K., Azorin-Molina, C., Bardin, M.Y., Barichivich, J., Barreira, S., Baxter, S., Beck, H.E., Becker, A., Bell, G.D., Bellouin, N., Belmont, M., Benedetti, A., Benedict, I., Bernhard, G.H., Berrisford, P., Berry, D.I., Bettio, L., Bhatt, U.S., Biskaborn, B.K., Bissolli, P., Bjella, K.L., Bjerke, J.K., Blake, E.S., Blenkinsop, S., Blunden, J., Bock, O., Bosilovich, M.G., Boucher, O., Box, J.E., Boyer, T., Braathen, G., Bringas, F.G., Bromwich, D.H., Brown, A., Brown, R., Brown, T.J., Buehler, S.A., Cáceres, L., Calderón, B., Camargo, S.J., Campbell, J.D., Campos Diaz, D.A., Cappelen, J., Carrea, L., Carrier, S.B., Carter, B.R., Castro, A.Y., Cetinic, I., Chambers, D.P., Chen, L., Cheng, L., Cheng, V.Y.S., Christiansen, H.H., Christy, J.R., Chung, E.-S., Claus, F., Clem, K.R., Coelho, C.A.S., Coldewey-Egbers, M., Colwell, S., Cooper, O.R., Cosca, C., Covey, C., Coy, L., Dávila, C.P., Davis, S.M., de Eyto, E., de Jeu, R.A.M., De Laat, J., Decharme, B., Degasperi, C.L., Degenstein, D., Demircan, M., Derksen, C., Dhurmea, K.R., Di Girolamo, L., Diamond, H.J., Diaz, E., Diniz, F.A., Dlugokencky, E.J., Dohan, K., Dokulil, M.T., Dolman, A.J., Domingues, C.M., Domingues, R., Donat, M.G., Dorigo, W.A., Drozdov, D.S., Druckenmiller, M.L., Dunn, R.J.H., Durre, I., Dutton, G.S., Elkharrim, M., Elkins, J.W., Epstein, H.E., Espinoza, J.C., Famiglietti, J.S., Farrell, S.L., Fausto, R.S., Feely, R.A., Feng, Z., Fenimore, C., Fettweis, X., Fioletov, V.E., Flemming, J., Fogt, R.L., Forbes, B.C., Foster, M.J., Francis, S.D., Franz, B.A., Frey, R.A., Frith, S.M., Froidevaux, L., Ganter, C., Garforth, J., Gerland, S., Gilson, J., Gleason, K., Gobron, N., Goetz, S., Goldenberg, S.B., Goni, G., Gray, A., Groo, J.-U., Gruber, A., Gu, G., Guard, C.C.P., Gupta, S.K., Gutiérrez, D., Haas, Christian, Hagos, S., Hahn, S., Haimberger, L., Hall, B.D., Halpert, M.S., Hamlington, B.D., Hanna, E., Hanssen-Bauer, I., Harris, I., Hazeleger, W., He, Q., Heidinger, A.K., Heim, Jr., Hemming, D.L., Hendricks, Stefan, Hernández, R., Hersbach, H.E., Hidalgo, H.G., Ho, S.-P.B., Holmes, R.M., Hu, C., Huang, B., Hubbard, K., Hubert, D., Hurst, D.F., Ialongo, I., Ijampy, J.A., Inness, A., Isaac, V., Isaksen, K., Ishii, M., Jeffries, M.O., Jevrejeva, S., Jia, G., Jiménez, C., Jin, X., John, V., Johnsen, B., Johnson, G.C., Johnson, K.S., Johnson, B., Jones, P.D., Jumaux, G., Kabidi, K., Kaiser, J.W., Karaköylü, E.M., Karlsen, S.-R., Karnauskas, M., Kato, S., Kazemi, A.F., Kelble, C., Keller, L.M., Kennedy, J., Kholodov, A.L., Khoshkam, M., Kidd, R., Killick, R., Kim, H., Kim, S.-J., King, A.D., King, B.A., Kipling, Z., Klotzbach, P.J., Knaff, J.A., Korhonen, J., Korshunova, N.N., Kramarova, N.A., Kratz, D.P., Kruger, A., Kruk, M.C., Krumpen, Thomas, Labbé, L., Ladd, C., Lakatos, M., Lakkala, K., Lander, M.A., Landschützer, P., Landsea, C.W., Lareau, N.P., Lavado-Casimiro, W., Lazzara, M.A., Lee, T.C., Leuliette, E., L�heureux, M., Li, B., Li, T., Lieser, J.L., Lim, J.-Y., Lin, I.-I., Liu, H., Locarnini, R., Loeb, N.G., Long, C.S., López, L.A., Lorrey, A.M., Loyola, D., Lumpkin, R., Luo, J.-J., Luojus, K., Lyman, J.M., Malkova, G.V., Manney, G.L., Marchenko, S.S., Marengo, J.A., Marin, D., Marquardt Collow, A.B., Marra, J.J., Marszelewski, W., Martens, B., Martínez-Güingla, R., Massom, R.A., May, L., Mayer, M., Mazloff, M., McBride, C., McCabe, M., McClelland, J.W., McEvoy, D.J., McGree, S., McVicar, T.R., Mears, C.A., Meier, W., Meijers, A., Mekonnen, A., Mengistu Tsidu, G., Menzel, W.P., Merchant, C.J., Meredith, M.P., Merrifield, M.A., Miller, B., Miralles, D.G., Misevicius, N., Mitchum, G.T., Mochizuki, Y., Monselesan, D., Montzka, S.A., Mora, N., Morice, C., Mosquera-Vásquez, K., Mostafa, A.E., Mote, T., Mudryk, L., Mühle, J., Mullan, A.B., Müller, R., Myneni, R., Nash, E.R., Nauslar, N.J., Nerem, R.S., Newman, P.A., Nicolas, J.P., Nieto, J.J., Noetzli, J., Osborn, T.J., Osborne, E., Overland, J., Oyunjargal, L., Park, T., Pasch, R.J., Pascual Ramírez, R., Pastor Saavedra, M.A., Paterson, A.M., Pearce, P.R., Pelto, M.S., Perovich, D., Petropavlovskikh, I., Pezza, A.B., Phillips, C., Phillips, D., Phoenix, G., Pinty, B., Pitts, M., Po-Chedley, S., Polashenski, C., Preimesberger, W., Purkey, S.G., Quispe, N., Rajeevan, M., Rakotoarimalala, C.L., Ramos, A.M., Ramos, I., Randel, W., Raynolds, M.K., Reagan, J., Reid, P., Reimer, C., Rémy, S., Revadekar, J.V., Richardson, A.D., Richter-Menge, J., Ricker, Robert, Ripaldi, A., Robinson, D.A., Rodell, M., Rodriguez Camino, E., Romanovsky, V.E., Ronchail, J., Rosenlof, K.H., Rösner, B., Roth, C., Rozanov, A., Rusak, J.A., Rustemeier, E., Rutishäuser, T., Sallée, J.-B., Sánchez-Lugo, A., Santee, M.L., Sawaengphokhai, P., Sayouri, A., Scambos, T.A., Scanlon, T., Scardilli, A.S., Schenzinger, V., Schladow, S.G., Schmid, C., Schmid, M., Schoeneich, P., Schreck, III, Selkirk, H.B., Sensoy, S., Shi, L., Shiklomanov, A.I., Shiklomanov, N.I., Shimpo, A., Shuman, C.A., Siegel, D.A., Sima, F., Simmons, A.J., Smeets, C.J.P.P., Smith, A., Smith, S.L., Soden, B., Sofieva, V., Sparks, T.H., Spence, J., Spencer, R.G.M., Spillane, S., Srivastava, A.K., Stabeno, P.J., Stackhouse, Jr., Stammerjohn, S., Stanitski, D.M., Steinbrecht, W., Stella, J.L., Stengel, M., Stephenson, T.S., Strahan, S.E., Streeter, C., Streletskiy, D.A., Sun-Mack, S., Suslova, A., Sutton, A.J., Swart, S., Sweet, W., Takahashi, K.S., Tank, S.E., Taylor, M.A., Tedesco, M., Thackeray, S.J., Thompson, P.R., Timbal, B., Timmermans, M.-L., Tobin, S., Tømmervik, H., Tourpali, K., Trachte, K., Tretiakov, M., Trewin, B.C., Triñanes, J.A., Trotman, A.R., Tschudi, M., Tye, M.R., van As, D., van de Wal, R.S.W., van der A, R.J., van der Schalie, R., van der Schrier, G., van der Werf, G.R., van Heerwaarden, C., Van Meerbeeck, C.J., Verburg, P., Vieira, G., Vincent, L.A., Vömel, H., Vose, R.S., Walker, D.A., Walsh, J.E., Wang, B., Wang, H., Wang, L., Wang, M., Wang, R., Wang, S.-H., Wanninkhof, R., Watanabe, S., Weber, M., Webster, M., Weerts, A., Weller, R.A., Westberry, T.K., Weyhenmeyer, G.A., Widlansky, M.J., Wijffels, S.E., Wilber, A.C., Wild, J.D., Willett, K.M., Wong, T., Wood, E.F., Woolway, R.I., Xue, Y., Yin, X., Yu, L., Zambrano, E., Zeyaeyan, S., Zhang, H.-M., Zhang, P., Zhao, G., Zhao, L., Zhou, X., Zhu, Z., Ziemke, J.R., Ziese, M., Andersen, A., Griffin, J., Hammer, G., Love-Brotak, S.E., Misch, D.J., Riddle, D.B., and Veasey, S.W.

Published
2019

6. Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment

Author

Abbott, B.W., Jones, J.B., Schuur, E.A.G., Chapin III, F.S., Bowden, W.B., Bret-Harte, M.S., Epstein, H.E., Flannigan, M.D., Harms, T.K., Hollingsworth, T.N., Mack, M.C., McGuire, A.D., Natali, S.M., Rocha, A.V., Tank, S.E., Turetsky, M.R., Vonk, J.E., Wickland, K.P., Aiken, G.R., Alexander, H.D., Amon, R.M.W., Benscoter, B.W., Bergeron, Y., Bishop, K., Blarquez, O., Bond-Lamberty, B., Breen, A.L., Buffam, I., Cai, Y., Carcaillet, C., Carey, S.K., Chen, J.M., Chen, H.Y.H., Christensen, T.R., Cooper, L.W., Cornelissen, J.H.C., de Groot, W.J., DeLuca, T.H., Dorrepaal, E., Fetcher, N., Finlay, J.C., Forbes, B.C., French, N.H.F., Gauthier, S., Girardin, M.P., Goetz, S.J., Goldammer, J.G., Gough, L., Grogan, P., Guo, L., Higuera, P.E., Hinzman, L., Hu, F.S., Hugelius, G., Jafarov, E.E., Jandt, R., Johnstone, J.F., Karlsson, J., Kasischke, E.S., Kattner, G., Kelly, R., Keuper, F., Kling, G.W., Kortelainen, P., Kouki, J., Kuhry, P., Laudon, H., Laurion, I., Macdonald, R.W., Mann, P.J., Martikainen, P.J., McClelland, J.W., Molau, U., Oberbauer, S.F., Olefeldt, D., Paré, D., Parisien, M., Payette, S., Peng, C., Pokrovsky, O.S., Rastetter, E.B., Raymond, P.A., Raynolds, M.K., Rein, G., Reynolds, J.F., Robards, M., Rogers, B.M., Schädel, C., Schaefer, K., Schmidt, I.K., Shvidenko, A., Sky, J., Spencer, R.G.M., Starr, G., Striegl, R.G., Teisserenc, R., Tranvik, L.J., Virtanen, T., Welker, J.M., Zimov, S., Abbott, B.W., Jones, J.B., Schuur, E.A.G., Chapin III, F.S., Bowden, W.B., Bret-Harte, M.S., Epstein, H.E., Flannigan, M.D., Harms, T.K., Hollingsworth, T.N., Mack, M.C., McGuire, A.D., Natali, S.M., Rocha, A.V., Tank, S.E., Turetsky, M.R., Vonk, J.E., Wickland, K.P., Aiken, G.R., Alexander, H.D., Amon, R.M.W., Benscoter, B.W., Bergeron, Y., Bishop, K., Blarquez, O., Bond-Lamberty, B., Breen, A.L., Buffam, I., Cai, Y., Carcaillet, C., Carey, S.K., Chen, J.M., Chen, H.Y.H., Christensen, T.R., Cooper, L.W., Cornelissen, J.H.C., de Groot, W.J., DeLuca, T.H., Dorrepaal, E., Fetcher, N., Finlay, J.C., Forbes, B.C., French, N.H.F., Gauthier, S., Girardin, M.P., Goetz, S.J., Goldammer, J.G., Gough, L., Grogan, P., Guo, L., Higuera, P.E., Hinzman, L., Hu, F.S., Hugelius, G., Jafarov, E.E., Jandt, R., Johnstone, J.F., Karlsson, J., Kasischke, E.S., Kattner, G., Kelly, R., Keuper, F., Kling, G.W., Kortelainen, P., Kouki, J., Kuhry, P., Laudon, H., Laurion, I., Macdonald, R.W., Mann, P.J., Martikainen, P.J., McClelland, J.W., Molau, U., Oberbauer, S.F., Olefeldt, D., Paré, D., Parisien, M., Payette, S., Peng, C., Pokrovsky, O.S., Rastetter, E.B., Raymond, P.A., Raynolds, M.K., Rein, G., Reynolds, J.F., Robards, M., Rogers, B.M., Schädel, C., Schaefer, K., Schmidt, I.K., Shvidenko, A., Sky, J., Spencer, R.G.M., Starr, G., Striegl, R.G., Teisserenc, R., Tranvik, L.J., Virtanen, T., Welker, J.M., and Zimov, S.

Abstract

As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%–85% of permafrost carbon release can still be avoided if human emissions are actively reduced.

Published
2016

7. Evidence for key enzymatic controls on metabolism of Arctic river organic matter

Author

Mann, P.J., Sobczak, W.V., LaRue, M.M., Bulygina, E., Davydova, A., Vonk, J.E., Schade, J., Davydov, S., Zimov, N., Holmes, R.M., Spencer, R.G.M., NWO-VENI: Ancient organic matter that matters: The fate of Siberian Yedoma deposits, and Organic geochemistry

Subjects
Arctic, organic matter decomposition, biogeochemistry, enzymes, aquatic, dissolved organic matter, global change, permafrost
Abstract

Permafrost thaw in the Arctic driven by climate change is mobilizing ancient terrigenous organic carbon (OC) into fluvial networks. Understanding the controls on metabolism of this OC is imperative for assessing its role with respect to climate feedbacks. In this study, we examined the effect of inorganic nutrient supply and dissolved organic matter (DOM) composition on aquatic extracellular enzyme activities (EEAs) in waters draining the Kolyma River Basin (Siberia), including permafrost-derived OC. Reducing the phenolic content of the DOM pool resulted in dramatic increases in hydrolase EEAs (e.g., phosphatase activity increased >28-fold) supporting the idea that high concentrations of polyphenolic compounds in DOM (e.g., plant structural tissues) inhibit enzyme synthesis or activity, limiting OC degradation. EEAs were significantly more responsive to inorganic nutrient additions only after phenolic inhibition was experimentally removed. In controlled mixtures of modern OC and thawed permafrost endmember OC sources, respiration rates per unit dissolved OC were 1.3–1.6 times higher in waters containing ancient carbon, suggesting that permafrost-derived OC was more available for microbial mineralization. In addition, waters containing ancient permafrost-derived OC supported elevated phosphatase and glucosidase activities. Based on these combined results, we propose that both composition and nutrient availability regulate DOM metabolism in Arctic aquatic ecosystems. Our empirical findings are incorporated into a mechanistic conceptual model highlighting two key enzymatic processes in the mineralization of riverine OM: (i) the role of phenol oxidase activity in reducing inhibitory phenolic compounds and (ii) the role of phosphatase in mobilizing organic P. Permafrost-derived DOM degradation was less constrained by this initial ‘phenolic-OM’ inhibition; thus, informing reports of high biological availability of ancient, permafrost-derived DOM with clear ramifications for its metabolism in fluvial networks and feedbacks to climate.

Published
2014

8. Evidence for key enzymatic controls on metabolism of Arctic river organic matter

Author

NWO-VENI: Ancient organic matter that matters: The fate of Siberian Yedoma deposits, Organic geochemistry, Mann, P.J., Sobczak, W.V., LaRue, M.M., Bulygina, E., Davydova, A., Vonk, J.E., Schade, J., Davydov, S., Zimov, N., Holmes, R.M., Spencer, R.G.M., NWO-VENI: Ancient organic matter that matters: The fate of Siberian Yedoma deposits, Organic geochemistry, Mann, P.J., Sobczak, W.V., LaRue, M.M., Bulygina, E., Davydova, A., Vonk, J.E., Schade, J., Davydov, S., Zimov, N., Holmes, R.M., and Spencer, R.G.M.

Published
2014

9. Evidence for anthropogenic 14C-enrichment in estuarine waters adjacent to the North Sea

Author

Ahad, J.M.E., Ganeshram, R.S., Spencer, R.G.M., Uher, G., Gulliver, P., and Bryant, C.

Subjects
GE
Abstract

[1] The isotopic composition (d13C and D14C) of high\ud molecular weight dissolved organic carbon (HMW DOC)\ud was studied in the Tyne and Tweed estuaries, NE England.\ud Despite significant removal of terrigenous HMW DOC in\ud the low salinity regions (S < 15), D14C remained modern\ud with little variation around 115%. This lack of apparent age\ud discrimination was attributed to either non-oxidative\ud removal or the absence of a significant proportion of old\ud refractory C in the HMW DOC pool. At S < 15, we\ud observed seaward increases in d13C and D14C. With no\ud documented local 14C inputs, we attributed non-bomb\ud related 14C-enrichment at S < 15 to a possible ‘lingering\ud effect’ of distal anthropogenic sources in near-coastal North\ud Sea HMW DOC. Given the global distribution of potential\ud sources, we propose that anthropogenic 14C should be\ud considered in assigning ages of DOC pools in near-coastal\ud waters and suggest its possible use as a tracer for DOC\ud transformations.

Published
2006

10. High biolability of ancient permafrost carbon upon thaw

Author

Vonk, J.E., Mann, P.J., Davydov, S., Davydova, A., Spencer, R.G.M., Schade, J., Sobczak, W.V., Zimov, S., Bulygina, E., Eglinton, T.I., Holmes, R.M., Vonk, J.E., Mann, P.J., Davydov, S., Davydova, A., Spencer, R.G.M., Schade, J., Sobczak, W.V., Zimov, S., Bulygina, E., Eglinton, T.I., and Holmes, R.M.

Published
2013

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