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北极多年冻土退化或致工业遗址污染物排放风险增大 快报文章
地球科学快报，2023年第08期
作者:  刘文浩
Microsoft Word(16Kb)  |  收藏  |  浏览/下载：544/0  |  提交时间：2023/04/25
Arctic  Permafrost  contamination  
Hydrothermal (NN)-N-15-N-15 abundances constrain the origins of mantle nitrogen 期刊论文
NATURE, 2020, 580 (7803) : 367-+
作者:  Zhao, Steven;  Jang, Cholsoon;  Liu, Joyce;  Uehara, Kahealani;  Gilbert, Michael;  Izzo, Luke;  Zeng, Xianfeng;  Trefely, Sophie;  Fernandez, Sully;  Carrer, Alessandro;  Miller, Katelyn D.;  Schug, Zachary T.;  Snyder, Nathaniel W.;  Gade, Terence P.;  Titchenell, Paul M.;  Rabinowitz, Joshua D.;  Wellen, Kathryn E.
收藏  |  浏览/下载：14/0  |  提交时间：2020/05/13

Nitrogen is the main constituent of the Earth'  s atmosphere, but its provenance in the Earth'  s mantle remains uncertain. The relative contribution of primordial nitrogen inherited during the Earth'  s accretion versus that subducted from the Earth'  s surface is unclear(1-6). Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare (NN)-N-15-N-15 isotopologue of N-2 as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel (Germany) and Yellowstone (USA), we derive estimates of mantle delta N-15 (the fractional difference in N-15/N-14 from air), N-2/Ar-36 and N-2/He-3. Our results show that negative delta N-15 values observed in gases, previously regarded as indicating a mantle origin for nitrogen(7-10), in fact represent dominantly air-derived N-2 that experienced N-15/N-14 fractionation in hydrothermal systems. Using two-component mixing models to correct for this effect, the (NN)-N-15-N-15 data allow extrapolations that characterize mantle endmember delta N-15, N-2/Ar-36 and N-2/He-3 values. We show that the Eifel region has slightly increased delta N-15 and N-2/Ar-36 values relative to estimates for the convective mantle provided by mid-ocean-ridge basalts(11), consistent with subducted nitrogen being added to the mantle source. In contrast, we find that whereas the Yellowstone plume has delta N-15 values substantially greater than that of the convective mantle, resembling surface components(12-15), its N-2/Ar-36 and N-2/He-3 ratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component. We provide a test of the subduction hypothesis with a two-box model, describing the evolution of mantle and surface nitrogen through geological time. We show that the effect of subduction on the deep nitrogen cycle may be less important than has been suggested by previous investigations. We propose instead that high mid-ocean-ridge basalt and plume delta N-15 values may both be dominantly primordial features.


  
Wafer-scale single-crystal hexagonal boron nitride monolayers on Cu (111) 期刊论文
NATURE, 2020, 579 (7798) : 219-+
作者:  Luong, Duy X.;  Bets, Ksenia V.;  Algozeeb, Wala Ali;  Stanford, Michael G.;  Kittrell, Carter;  Chen, Weiyin;  Salvatierra, Rodrigo V.;  Ren, Muqing;  McHugh, Emily A.;  Advincula, Paul A.;  Wang, Zhe;  Bhatt, Mahesh;  Guo, Hua;  Mancevski, Vladimir;  Shahsavari, Rouzbeh
收藏  |  浏览/下载：80/0  |  提交时间：2020/07/03

Ultrathin two-dimensional (2D) semiconducting layered materials offer great potential for extending Moore'  s law of the number of transistors in an integrated circuit(1). One key challenge with 2D semiconductors is to avoid the formation of charge scattering and trap sites from adjacent dielectrics. An insulating van der Waals layer of hexagonal boron nitride (hBN) provides an excellent interface dielectric, efficiently reducing charge scattering(2,3). Recent studies have shown the growth of single-crystal hBN films on molten gold surfaces(4) or bulk copper foils(5). However, the use of molten gold is not favoured by industry, owing to its high cost, cross-contamination and potential issues of process control and scalability. Copper foils might be suitable for roll-to-roll processes, but are unlikely to be compatible with advanced microelectronic fabrication on wafers. Thus, a reliable way of growing single-crystal hBN films directly on wafers would contribute to the broad adoption of 2D layered materials in industry. Previous attempts to grow hBN monolayers on Cu (111) metals have failed to achieve mono-orientation, resulting in unwanted grain boundaries when the layers merge into films(6,7). Growing single-crystal hBN on such high-symmetry surface planes as Cu (111)(5,8) is widely believed to be impossible, even in theory. Nonetheless, here we report the successful epitaxial growth of single-crystal hBN monolayers on a Cu (111) thin film across a two-inch c-plane sapphire wafer. This surprising result is corroborated by our first-principles calculations, suggesting that the epitaxial growth is enhanced by lateral docking of hBN to Cu (111) steps, ensuring the mono-orientation of hBN monolayers. The obtained single-crystal hBN, incorporated as an interface layer between molybdenum disulfide and hafnium dioxide in a bottom-gate configuration, enhanced the electrical performance of transistors. This reliable approach to producing wafer-scale single-crystal hBN paves the way to future 2D electronics.


  
Impact of an historic underground gas well blowout on the current methane chemistry in a shallow groundwater system 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2018, 115 (2) : 296-301
作者:  Schout, Gilian;  Hartog, Niels;  Hassanizadeh, S. Majid;  Griffioen, Jasper
收藏  |  浏览/下载：7/0  |  提交时间：2019/11/27
groundwater contamination  well blowouts  methane  isotopic fingerprinting  anaerobic methane oxidation  
Corrective Action Decision Document/Closure Report for Corrective Action Unit 550: Smoky Contamination Area Nevada National Security Site, Nevada, Revision 0 科技报告
来源：US Department of Energy (DOE). 出版年： 2015
作者:  Matthews, Patrick K.
收藏  |  浏览/下载：0/0  |  提交时间：2019/04/05
CADD/CR  CAU 550  Smoky Site  Contamination Area  
Radiochemically-Supported Microbial Communities: A Potential Mechanism for Biocolloid Production of Importance to Actinide Transport 科技报告
来源：US Department of Energy (DOE). 出版年： 2014
作者:  Moser, Duane P;  Hamilton-Brehm, Scott D;  Fisher, Jenny C;  Bruckner, James C;  Kruger, Brittany;  Sackett, Joshua;  Russell, Charles E;  Onstott, Tullis C;  Czerwinski, Ken
收藏  |  浏览/下载：17/0  |  提交时间：2019/04/05
Due to the legacy of Cold War nuclear weapons testing  the Nevada National Security Site (NNSS  formerly known as the Nevada Test Site (NTS)) contains millions of Curies of radioactive contamination. Presented here is a summary of the results of the first comprehensive study of subsurface microbial communities of radioactive and nonradioactive aquifers at this site. To achieve the objectives of this project  cooperative actions between the Desert Research Institute (DRI)  the Nevada Field Office of the National Nuclear Security Administration (NNSA)  the Underground Test Area Activity (UGTA)  and contractors such as Navarro-Interra (NI)  were required. Ultimately  fluids from 17 boreholes and two water-filled tunnels were sampled (sometimes on multiple occasions and from multiple depths) from the NNSS  the adjacent Nevada Test and Training Range (NTTR)  and a reference hole in the Amargosa Valley near Death Valley. The sites sampled ranged from highly-radioactive nuclear device test cavities to uncontaminated perched and regional aquifers. Specific areas sampled included recharge  intermediate  and discharge zones of a 100  000-km2 internally-draining province  known as the Death Valley Regional Flow System (DVRFS)  which encompasses the entirety of the NNSS/NTTR and surrounding areas. Specific geological features sampled included: West Pahute and Ranier Mesas (recharge zone)  Yucca and Frenchman Flats (transitional zone)  and the Western edge of the Amargosa Valley near Death Valley (discharge zone). The original overarching question underlying the proposal supporting this work was stated as: Can radiochemically-produced substrates support indigenous microbial communities and subsequently stimulate biocolloid formation that can affect radionuclides in NNSS subsurface nuclear test/detonation sites? Radioactive and non-radioactive groundwater samples were thus characterized for physical parameters  aqueous geochemistry  and microbial communities using both DNA- and cultivation-based tools in an effort to understand the drivers of microbial community structure (including radioactivity) and microbial interactions with select radionuclides and other factors across the range of habitats surveyed.  
Assessing the Role of Iron Sulfides in the Long Term Sequestration of Uranium by Sulfate-Reducing Bacteria 科技报告
来源：US Department of Energy (DOE). 出版年： 2014
作者:  Hayes, Kim F.;  Bi, Yuqiang;  Carpenter, Julian;  Hyng, Sung Pil;  Rittmann, Bruce E.;  Zhou, Chen;  Vannela, Raveender;  Davis, James A.
收藏  |  浏览/下载：7/0  |  提交时间：2019/04/05
uranium groundwater contamination  sulfate reducing bacteria  Desulfovibrio vulgaris  mackinawite oxidation  uraninite oxidation  
Release of aged contaminants from weathered sediments: Effects of sorbate speciation on scaling of reactive transport 科技报告
来源：US Department of Energy (DOE). 出版年： 2012
作者:  Chorover, Jon;  Perdrial, Nico;  Mueller, Karl;  Strepka, Caleb;  O’Day, Peggy;  Rivera, Nelson;  Um, Wooyong;  Chang, Hyun-Shik;  Steefel, Carl;  Thompson, Aaron
收藏  |  浏览/下载：4/0  |  提交时间：2019/04/05
contamination  remediation  speciation  transport  
Final Project Report: "Exploratory Research: Mercury Stable Isotopes as Indicators of the Biogeochemical Cycling of Mercury" 科技报告
来源：US Department of Energy (DOE). 出版年： 2012
作者:  Johnson, Thomas M
收藏  |  浏览/下载：0/0  |  提交时间：2019/04/05
mercury  water  contamination  Y-12 plant  stable isotopes  biogeochmistry  
Using Downhole Probes to Locate and Characterize Buried Transuranic and Mixed Low Level Waste 科技报告
来源：US Department of Energy (DOE). 出版年： 2012
作者:  Steinman, Donald K;  Bramblett, Richard L;  Hertzog, Russel C
收藏  |  浏览/下载：1/0  |  提交时间：2019/04/05
pulsed neutron generators  borehole logging  probes  neutron activation  prompt fission  transuranic  mixed low level waste  chlorine  volatile organic compounds  subsurface disposal  contamination  Weapons Complex  capture gamma rays  inelastic gamma ray