A comparison of non-hydrolytic methods for extracting amino acids and proteins from coastal marine sediments     

Brook L. Nunn  Richard G. Keil 《Marine Chemistry》2006

Advances in analytical techniques now allow for the potential analysis of intact peptides and proteins isolated from marine sediments. However, there is no established technique for the extraction of macromolecular materials from marine sediments. Six different methods for extracting the amino acid component from coastal marine sediments were compared to the standard hot acid hydrolysis technique for their percent recovery and amino acid composition. The standard hot acid hydrolysis on dried, whole sediments released the greatest concentration of total amino acids (PS-THAA; 3.52 mg gdwt^− 1 ± 10% (SMD)), yet this only accounted for 22% of the total nitrogen in Puget Sound sediments (Washington, USA). Repeated hydrolysis of the same samples did not improve the recovery of nitrogen by more than an additional 10%. Base extraction (0.5 N NaOH) was the second best method for recovering amino acid nitrogen, releasing 60% of the Puget Sound total hydrolyzable amino acids (PS-THAA) (corresponding to 13% of the total sedimentary nitrogen), and has the advantage that it does not rely on peptide hydrolysis to free the nitrogenous component from the sediment matrix. The amino acid distribution of the 0.5 N NaOH extract was not significantly different than the initial THAA. Other non-hydrolyzing methods released lower yields of amino acids (Triton X-100 ≥ hot water > 50 mM NH₄HCO₃ > HF), but might prove to be of use to investigators interested in specific fractions of sedimentary organic nitrogen because these four methods had distinctly different amino acid compositions (enrichments in basic amino acids and depletions in acidic amino acids). Treatments with HF both before and after traditional hydrolysis and/or extractions with base did not release any more of the sedimentary nitrogen. Our results are consistent with the hypothesis that a large fraction of the sedimentary nitrogen (TN) is protected within an organic matrix.  相似文献   

The Alaska Wrangell Arc: ~30 Ma of subduction‐related magmatism along a still active arc‐transform junction     

Matthew E. Brueseke  Jeffrey A. Benowitz  Jeffrey M. Trop  Kailyn N. Davis  Samuel E. Berkelhammer  Paul W. Layer  Bethany K. Morter 《地学学报》2019,31(1):59-66

The Oligocene to Present Wrangell Volcanic Belt (WVB) extends for ~500 km across south‐central Alaska (USA) into Canada at a volcanic arc‐transform junction. Previously, geochemistry documented mantle wedge and slab‐edge melting in <12 Ma WVB volcanic rocks; new geochemistry shows that the same processes characterized ~18–30 Ma WVB magmatism in Alaska. New ⁴⁰Ar/³⁹Ar ages demonstrate that WVB magmatism in Alaska initiated at ~30 Ma due to flat‐slab subduction of the Yakutat microplate and that the dextral Totschunda fault was active at this time. Our results, together with prior studies, show that Alaskan WVB magmatism occurred chiefly due to subduction and should be considered a volcanic arc (e.g. the Wrangell Arc). The WVB provides a long‐term geological record of subduction, strike‐slip and magmatism. Slab‐edge upwelling, flat‐slab defocused fluid‐flux and faults acting as magma conduits are likely responsible for the exceptionally large volcanoes and high eruption rates of the Wrangell Arc.  相似文献   

Adding our leaves: A community-wide perspective on research directions in ecohydrology     

Christina L. Tague  Shirley A. Papuga  Cynthia Gerlein-Safdi  Salli Dymond  Ryan R. Morrison  Elizabeth W. Boyer  Diego Riveros-Iregui  Elizabeth Agee  Bhavna Arora  Yannis G. Dialynas  Amy Hansen  Stefan Krause  Sylvain Kuppel  Steven P Loheide II  Stanislaus J. Schymanski  Samuel C Zipper 《水文研究》2020,34(7):1665-1673

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Direct and semi-direct aerosol radiative effect on the Mediterranean climate variability using a coupled regional climate system model     

Pierre Nabat  Samuel Somot  Marc Mallet  Florence Sevault  Marc Chiacchio  Martin Wild 《Climate Dynamics》2015,44(3-4):1127-1155

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Modeling the exceptional south Foehn event (Garmij) over the Alborz Mountains during the extreme forest fire of December 2005     

Abbas Mofidi  Iman Soltanzadeh  Yadollah Yousefi  Azar Zarrin  Mohsen Soltani  Jafar Masoompour Samakosh  Ghasem Azizi  Samuel T. K. Miller 《Natural Hazards》2015,75(3):2489-2518

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Overcoming barriers to climate change information management in small island developing states: lessons from pacific SIDS     

Samuel Mackay  Rebecca Brown  Makelesi Gonelevu  Netatua Pelesikoti  Talei Kocovanua  Rebecca Iaken 《Climate Policy》2019,19(1):125-138

We live in a rapidly advancing digital information age where the ability to discover, access and utilize high-quality information in a reliable and timely manner is often assumed to be the norm. However, this is not always the experience of researchers, practitioners and decision makers responding to the challenges of a rapidly changing climate, despite the billions now being made available for investment in climate change adaptation initiatives throughout the world and particularly in developing countries. In recognition of the importance of information in adaptation planning, Article 7.7 of the Paris Agreement sets out clear guidance for parties to develop, share, manage and deliver climate change knowledge, information and data as a means to strengthening cooperation and action on adaptation. This article provides some key lessons and insights on climate change information and knowledge management (IKM) in small island developing States (SIDS) from the perspective of Pacific SIDS. A situation analysis of current climate change IKM practices in Fiji, Tonga and Vanuatu was conducted and key barriers to effective climate change IKM identified. The outcome of this article is a range of pragmatic policy considerations for overcoming common barriers to climate change IKM in the Pacific, which may be of value to SIDS more widely.

Key policy insights

• The partnership approach of co-investigating climate change IKM barriers in collaboration with Pacific SIDS generated considerable trust, a shared purpose and therefore rich IKM lessons and insights.

• Turning climate change IKM aspirations into practice is significantly more complicated than expected, and requires a long-term commitment from both national governments and development partners.

• Pacific SIDS need to establish national guiding climate change IKM Frameworks that leverage rather than duplicate growing national investments in whole-of-government IKM.

• Reframing climate change IKM in the Pacific towards demand and user needs will be critical to ensuring widespread ownership and participation in IKM solutions that lead to greater adaptation and resilience outcomes.

• It is also critical that IKM activities in SIDS support the development of national capacity to scope, develop, deploy and maintain decision support systems.

• Federated IKM systems are ideal for encouraging greater IKM collaboration.

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Climate variability and rural livelihood sustainability: evidence from communities along the Black Volta River in Ghana     

Yiridomoh  Gordon Yenglier  Sullo  Cyril  Bonye  Samuel Ziem 《GeoJournal》2021,86(4):1527-1543

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Dramatic decrease of pelagic carbonate production by nannoplankton across the Early Toarcian anoxic event (T-OAE)     

Emanuela Mattioli  Bernard Pittet  Laurent Petitpierre  Samuel Mailliot 《Global and Planetary Change》2009,65(3-4):134-145

In this account we present estimates of nannofossil fluxes in four sections and one borehole all belonging to the Early Jurassic western Tethys. This study aims to map the distribution of pelagic carbonate production across the Early Toarcian anoxic event (T-OAE), and to understand which environmental parameters did control such production. Our results indicate important changes in carbonate production by nannoplankton occurring within the western Tethys and its variations through time. Nannofossil fluxes (specimens per m² per year) are extremely low during the T-OAE in all the studied settings. Higher fluxes are encountered in the westernmost part of the Tethys Ocean before the T-OAE, whilst pelagic carbonate production shifted towards the northern margin of the Tethys after the recovery from anoxic conditions. The dramatic decrease in nannoplankton production during the T-OAE has been interpreted in previous works as a biocalcification crisis related to high pCO₂ in the atmosphere/hydrosphere system. Although a high pCO₂ may have lowered the carbonate saturation state of Early Jurassic oceans and finally hampered biocalcification, we speculate that the most important effects of CO₂ increase were indirect, and affected pelagic producers via changes on climate and sea-level. Namely, it seems that precipitation/evaporation budgets and continental runoff that controlled nutrient levels and salinity in surface oceanic waters were important factors for pelagic biocalcifiers.  相似文献   

Probability distributions for carbon emissions and atmospheric response     

Clifford E. Singer  T. S. Gopi Rethinaraj  Samuel Addy  David Durham  Murat Isik  Madhu Khanna  Brandon Kuehl  Jianding Luo  Wilma Quimio  Kothavari Rajendran  Donna Ramirez  Ji Qiang  Jürgen Scheffran  T. Nedjla Tiouririne  Junli Zhang 《Climatic change》2008,88(3-4):309-342

Probability distributions for carbon burning, atmospheric CO₂, and global average temperature are produced by time series calibration of models of utility optimization and carbon and heat balance using log-linear production functions. Population growth is used to calibrate a logistically evolving index of development that influences production efficiency. Energy production efficiency also includes a coefficient that decreases linearly with decreasing carbon intensity of energy production. This carbon intensity is a piecewise linear function of fossil carbon depletion. That function is calibrated against historical data and extrapolated by sampling a set of hypotheses about the impact on the carbon intensity of energy production of depleting fluid fossil fuel resources and increasing cumulative carbon emissions. Atmospheric carbon balance is determined by a first order differential equation with carbon use rates and cumulative carbon use as drivers. Atmospheric CO₂ is a driver in a similar heat balance. Periodic corrections are included where required to make residuals between data and model results indistinguishable from independently and identically distributed normal distributions according to statistical tests on finite Fourier power spectrum amplitudes and nearest neighbor correlations. Asymptotic approach to a sustainable non-fossil energy production is followed for a global disaggregation into a tropical/developing and temperate/more-developed region. The increase in the uncertainty of global average temperature increases nearly quadratically with the increase in the temperature from the present through the next two centuries.  相似文献   

Characterization of manganese oxide precipitates from Appalachian coal mine drainage treatment systems     

Hui Tan  Gengxin Zhang  Peter J. Heaney  Samuel M. Webb  William D. Burgos 《Applied Geochemistry》2010

The removal of Mn(II) from coal mine drainage (CMD) by chemical addition/active treatment can significantly increase treatment costs. Passive treatment for Mn removal involves promotion of biological oxidative precipitation of manganese oxides (MnO_x). Manganese(II) removal was studied in three passive treatment systems in western Pennsylvania that differed based on their influent Mn(II) concentrations (20–150 mg/L), system construction (±inoculation with patented Mn(II)-oxidizing bacteria), and bed materials (limestone vs. sandstone). Manganese(II) removal occurred at pH values as low as 5.0 and temperatures as low as 2 °C, but was enhanced at circumneutral pH and warmer temperatures. Trace metals such as Zn, Ni and Co were removed effectively, in most cases preferentially, into the MnO_x precipitates. Based on synchrotron radiation X-ray diffraction and Mn K-edge extended X-ray absorption fine structure spectroscopy, the predominant Mn oxides at all sites were poorly crystalline hexagonal birnessite, triclinic birnessite and todorokite. The surface morphology of the MnO_x precipitates from all sites was coarse and “sponge-like” composed of nm-sized lathes and thin sheets. Based on scanning electron microscopy (SEM), MnO_x precipitates were found in close proximity to both prokaryotic and eukaryotic organisms. The greatest removal efficiency of Mn(II) occurred at the one site with a higher pH in the bed and a higher influent total organic C (TOC) concentration (provided by an upstream wetland). Biological oxidation of Mn(II) driven by heterotrophic activity was most likely the predominant Mn removal mechanism in these systems. Influent water chemistry and Mn(II) oxidation kinetics affected the relative distribution of MnO_x mineral assemblages in CMD treatment systems.  相似文献