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Mud in rivers transported as flocculated and suspended bed material 期刊论文
NATURE GEOSCIENCE, 2020
作者:  Lamb, Michael P.;  de Leeuw, Jan;  Fischer, Woodward W.;  Moodie, Andrew J.;  Venditti, Jeremy G.;  Nittrouer, Jeffrey A.;  Haught, Daniel;  Parker, Gary
收藏  |  浏览/下载:11/0  |  提交时间:2020/07/09
A remnant planetary core in the hot-Neptune desert 期刊论文
NATURE, 2020, 583 (7814) : 39-+
作者:  David J. Armstrong;  Thé;  o A. Lopez;  Vardan Adibekyan;  Richard A. Booth;  Edward M. Bryant;  Karen A. Collins;  Magali Deleuil;  Alexandre Emsenhuber;  Chelsea X. Huang;  George W. King;  Jorge Lillo-Box;  Jack J. Lissauer;  Elisabeth Matthews;  Olivier Mousis;  Louise D. Nielsen;  Hugh Osborn;  Jon Otegi;  Nuno C. Santos;  ;  rgio G. Sousa;  Keivan G. Stassun;  Dimitri Veras;  Carl Ziegler;  Jack S. Acton;  Jose M. Almenara;  David R. Anderson;  David Barrado;  Susana C. C. Barros;  Daniel Bayliss;  Claudia Belardi;  Francois Bouchy;  ;  sar Briceñ;  o;  Matteo Brogi;  David J. A. Brown;  Matthew R. Burleigh;  Sarah L. Casewell;  Alexander Chaushev;  David R. Ciardi;  Kevin I. Collins;  Knicole D. Coló;  n;  Benjamin F. Cooke;  Ian J. M. Crossfield;  Rodrigo F. Dí;  az;  Elisa Delgado Mena;  Olivier D. S. Demangeon;  Caroline Dorn;  Xavier Dumusque;  Philipp Eigmü;  ller;  Michael Fausnaugh;  Pedro Figueira;  Tianjun Gan;  Siddharth Gandhi;  Samuel Gill;  Erica J. Gonzales;  Michael R. Goad;  Maximilian N. Gü;  nther;  Ravit Helled;  Saeed Hojjatpanah;  Steve B. Howell;  James Jackman;  James S. Jenkins;  Jon M. Jenkins;  Eric L. N. Jensen;  Grant M. Kennedy;  David W. Latham;  Nicholas Law;  Monika Lendl;  Michael Lozovsky;  Andrew W. Mann;  Maximiliano Moyano;  James McCormac;  Farzana Meru;  Christoph Mordasini;  Ares Osborn;  Don Pollacco;  Didier Queloz;  Liam Raynard;  George R. Ricker;  Pamela Rowden;  Alexandre Santerne;  Joshua E. Schlieder;  Sara Seager;  Lizhou Sha;  Thiam-Guan Tan;  Rosanna H. Tilbrook;  Eric Ting;  Sté;  phane Udry;  Roland Vanderspek;  Christopher A. Watson;  Richard G. West;  Paul A. Wilson;  Joshua N. Winn;  Peter Wheatley;  Jesus Noel Villasenor;  Jose I. Vines;  Zhuchang Zhan
收藏  |  浏览/下载:17/0  |  提交时间:2020/07/06

The interiors of giant planets remain poorly understood. Even for the planets in the Solar System, difficulties in observation lead to large uncertainties in the properties of planetary cores. Exoplanets that have undergone rare evolutionary processes provide a route to understanding planetary interiors. Planets found in and near the typically barren hot-Neptune '  desert'  (1,2)(a region in mass-radius space that contains few planets) have proved to be particularly valuable in this regard. These planets include HD149026b(3), which is thought to have an unusually massive core, and recent discoveries such as LTT9779b(4)and NGTS-4b(5), on which photoevaporation has removed a substantial part of their outer atmospheres. Here we report observations of the planet TOI-849b, which has a radius smaller than Neptune'  s but an anomalously large mass of39.1-2.6+2.7Earth masses and a density of5.2-0.8+0.7grams per cubic centimetre, similar to Earth'  s. Interior-structure models suggest that any gaseous envelope of pure hydrogen and helium consists of no more than3.9-0.9+0.8 per cent of the total planetary mass. The planet could have been a gas giant before undergoing extreme mass loss via thermal self-disruption or giant planet collisions, or it could have avoided substantial gas accretion, perhaps through gap opening or late formation(6). Although photoevaporation rates cannot account for the mass loss required to reduce a Jupiter-like gas giant, they can remove a small (a few Earth masses) hydrogen and helium envelope on timescales of several billion years, implying that any remaining atmosphere on TOI-849b is likely to be enriched by water or other volatiles from the planetary interior. We conclude that TOI-849b is the remnant core of a giant planet.


Observations of TOI-849b reveal a radius smaller than Neptune'  s but a large mass of about 40 Earth masses, indicating that the planet is the remnant core of a gas giant.


  
Distinct formation history for deep-mantle domains reflected in geochemical differences 期刊论文
NATURE GEOSCIENCE, 2020, 13 (7) : 511-+
作者:  Doucet, Luc S.;  Li, Zheng-Xiang;  Gamal El Dien, Hamed;  Pourteau, Amaury;  Murphy, J. Brendan;  Collins, William J.;  Mattielli, Nadine;  Olierook, Hugo K. H.;  Spencer, Christopher J.;  Mitchell, Ross N.
收藏  |  浏览/下载:6/0  |  提交时间:2020/07/06
Weak magnetic field changes over the Pacific due to high conductance in lowermost mantle 期刊论文
NATURE GEOSCIENCE, 2020, 13 (7) : 516-+
作者:  Dumberry, Mathieu;  More, Colin
收藏  |  浏览/下载:1/0  |  提交时间:2020/07/06
A seawater throttle on H-2 production in Precambrian serpentinizing systems 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (26) : 14756-14763
作者:  Tutolo, Benjamin M.;  Seyfried, William E., Jr.;  Tosca, Nicholas J.
收藏  |  浏览/下载:9/0  |  提交时间:2020/06/22
serpentinization  Precambrian  atmosphere redox state  origins of life  
Greater flood risks in response to slowdown of tropical cyclones over the coast of China 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (26) : 14751-14755
作者:  Lai, Yangchen;  Li, Jianfeng;  Gu, Xihui;  Chen, Yongqin David;  Kong, Dongdong;  Gan, Thian Yew;  Liu, Maofeng;  Li, Qingquan;  Wu, Guofeng
收藏  |  浏览/下载:16/0  |  提交时间:2020/06/22
tropical cyclones  translation speed  local rainfall totals  flood risks  
Human influence has intensified extreme precipitation in North America 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (24) : 13308-13313
作者:  Kirchmeier-Young, Megan C.;  Zhang, Xuebin
收藏  |  浏览/下载:6/0  |  提交时间:2020/06/09
extreme precipitation  attribution  regional climate change  
Patterns and trends of Northern Hemisphere snow mass from 1980 to 2018 期刊论文
NATURE, 2020, 581 (7808) : 294-+
作者:  Ibrahim, Nizar;  Maganuco, Simone;  Dal Sasso, Cristiano;  Fabbri, Matteo;  Auditore, Marco;  Bindellini, Gabriele;  Martill, David M.;  Zouhri, Samir;  Mattarelli, Diego A.;  Unwin, David M.;  Wiemann, Jasmina;  Bonadonna, Davide;  Amane, Ayoub;  Jakubczak, Juliana;  Joger, Ulrich;  Lauder, George V.;  Pierce, Stephanie E.
收藏  |  浏览/下载:18/0  |  提交时间:2020/05/25

Warming surface temperatures have driven a substantial reduction in the extent and duration of Northern Hemisphere snow cover(1-3). These changes in snow cover affect Earth'  s climate system via the surface energy budget, and influence freshwater resources across a large proportion of the Northern Hemisphere(4-6). In contrast to snow extent, reliable quantitative knowledge on seasonal snow mass and its trend is lacking(7-9). Here we use the new GlobSnow 3.0 dataset to show that the 1980-2018 annual maximum snow mass in the Northern Hemisphere was, on average, 3,062 +/- 35 billion tonnes (gigatonnes). Our quantification is for March (the month that most closely corresponds to peak snow mass), covers non-alpine regions above 40 degrees N and, crucially, includes a bias correction based on in-field snow observations. We compare our GlobSnow 3.0 estimates with three independent estimates of snow mass, each with and without the bias correction. Across the four datasets, the bias correction decreased the range from 2,433-3,380 gigatonnes (mean 2,867) to 2,846-3,062 gigatonnes (mean 2,938)-a reduction in uncertainty from 33% to 7.4%. On the basis of our bias-corrected GlobSnow 3.0 estimates, we find different continental trends over the 39-year satellite record. For example, snow mass decreased by 46 gigatonnes per decade across North America but had a negligible trend across Eurasia  both continents exhibit high regional variability. Our results enable a better estimation of the role of seasonal snow mass in Earth'  s energy, water and carbon budgets.


Applying a bias correction to a state-of-the-art dataset covering non-alpine regions of the Northern Hemisphere and to three other datasets yields a more constrained quantification of snow mass in March from 1980 to 2018.


  
Evidence for sodium-rich alkaline water in the Tagish Lake parent body and implications for amino acid synthesis and racemization 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (21) : 11217-11219
作者:  White, Lee F.;  Tait, Kimberly T.;  Langelier, Brian;  Lymer, Elizabeth A.;  Cernok, Ana;  Kizovski, Tanya V.;  Ma, Chi;  Tschauner, Oliver;  Nicklin, Richard I.
收藏  |  浏览/下载:6/0  |  提交时间:2020/05/13
Tagish Lake  framboidal magnetite  atom probe tomography  amino acid  
Millennial-scale hydroclimate control of tropical soil carbon storage 期刊论文
NATURE, 2020, 581 (7806) : 63-+
作者:  Lam, Tommy Tsan-Yuk;  Jia, Na;  Zhang, Ya-Wei;  Shum, Marcus Ho-Hin;  Jiang, Jia-Fu;  Zhu, Hua-Chen;  Tong, Yi-Gang;  Shi, Yong-Xia;  Ni, Xue-Bing;  Liao, Yun-Shi;  Li, Wen-Juan;  Jiang, Bao-Gui;  Wei, Wei;  Yuan, Ting-Ting;  Zheng, Kui;  Cui, Xiao-Ming;  Li, Jie;  Pei, Guang-Qian
收藏  |  浏览/下载:25/0  |  提交时间:2020/05/13

Over the past 18,000 years, the residence time and amount of soil carbon stored in the Ganges-Brahmaputra basin have been controlled by the intensity of Indian Summer Monsoon rainfall, with greater carbon destabilization during wetter, warmer conditions.


The storage of organic carbon in the terrestrial biosphere directly affects atmospheric concentrations of carbon dioxide over a wide range of timescales. Within the terrestrial biosphere, the magnitude of carbon storage can vary in response to environmental perturbations such as changing temperature or hydroclimate(1), potentially generating feedback on the atmospheric inventory of carbon dioxide. Although temperature controls the storage of soil organic carbon at mid and high latitudes(2,3), hydroclimate may be the dominant driver of soil carbon persistence in the tropics(4,5)  however, the sensitivity of tropical soil carbon turnover to large-scale hydroclimate variability remains poorly understood. Here we show that changes in Indian Summer Monsoon rainfall have controlled the residence time of soil carbon in the Ganges-Brahmaputra basin over the past 18,000 years. Comparison of radiocarbon ages of bulk organic carbon and terrestrial higher-plant biomarkers with co-located palaeohydrological records(6) reveals a negative relationship between monsoon rainfall and soil organic carbon stocks on a millennial timescale. Across the deglaciation period, a depletion of basin-wide soil carbon stocks was triggered by increasing rainfall and associated enhanced soil respiration rates. Our results suggest that future hydroclimate changes in tropical regions are likely to accelerate soil carbon destabilization, further increasing atmospheric carbon dioxide concentrations.