On the detection of newly created CN radicals in comets     

Bertram Donn  Regina J. Cody 《Icarus》1978,34(2):436-440

Laboratory investigations of CN radical formation by photodissociation of parent molecules have suggested the possibility of observing emission lines in cometary spectra from newly formed CN radicals. These laboratory studies have shown that high initial internal excitation of CN is the rule with excitation of rotational levels N up to 70. In the collisionless environment of the cometary atmosphere this initial excitation would yield a corresponding distribution for the lowest vibrational level of the ground X²Σ⁺ state. Our calculations show that it is feasible with present observational techniques to detect photochemically excited lines with N ～ 30 in the 0-0 band of the violet system.  相似文献   

Can silicon monoxide grains be responsible for the interstellar 9.7 micrometer absorption band?     

J. Gürtler  Regina Schmidt  J. Dorschner  C. Friedemann 《Astrophysics and Space Science》1981,80(1):249-255

In this paper results of an experimental investigation of the spectra of submicrometersized silicon monoxide grains are presented. The grains manufactured from commercial SiO were prepared according to the Jena IR spectroscopy program for particulates of cosmic importance. The comparison of the laboratory spectra with those derived by means of Mie calculations using published refractive indices of bulk SiO revealed a fundamental discrepancy concerning the number and the positions of the bands. Therefore, the experimental SiO grains are suggested to change their internal structural state by the heating connected with the pressing of the KBr pellets, where the grains are embedded in. This sensitivity against heating by some hundred K rules out that SiO grains can be responsible for the 9.7 m circumstellar as well as interstellar spectral feature.  相似文献   

GHG mitigation of agricultural peatlands requires coherent policies   总被引：1，自引：0，他引：1  

Kristiina Regina  Arif Budiman  Mogens H. Greve  Arne Grønlund  Åsa Kasimir  Heikki Lehtonen 《Climate Policy》2016,16(4):522-541

As soon as peat soil is drained for agricultural production, the peat starts to degrade, which causes emissions to the atmosphere. In countries with large peatland areas, the GHG mitigation potential related to management of these soils is often estimated as the highest amongst the measures available in agriculture. Although the facts are well known, the policies leading to diminished emissions are often difficult to implement. We have analysed the reasons why the mitigation potential is not fully utilized and what could be done better in national implementation of climate policies. Four cases are used to illustrate the necessary steps to reach mitigation targets: determining the amount and properties of peat soils, estimating the potential, costs and feasibility of the mitigation measures, and selecting and implementing the best measures. A common feature for all of the cases was that national and international climate policies have increased the public interest in GHG emissions from peat soils and increased the pressure for mitigation. Basically the same factors restrict the implementation of mitigation measures in all countries with significant peat soil areas. The most important of these is lack of policy coherence, e.g. ignoring climate policies when planning land use or agricultural policies. We conclude that GHG mitigation is achieved only if other policies, especially national regulations and strategies, are in line with climate policies.

Policy relevance

Agricultural peat soils could be used to help reach GHG mitigation goals in many countries, but the full potential of mitigation of peat soils is not used. Although peatland cultivation inevitably leads to loss of the whole peat layer and high emissions, there are few incentives or regulation to effectively minimize these losses. This article discusses the possibilities to reduce GHG emissions from agricultural peat soils, with specific emphasis on the barriers of implementing mitigation measures nationally. The lessons learned from the selected cases emphasize the role of all policy makers and their cooperation in planning coherent policies for achieving the goals determined by climate policies.  相似文献   

Adsorption of thorium and protactinium onto different particle types: experimental findings     

Walter Geibert  Regina Usbeck 《Geochimica et cosmochimica acta》2004,68(7):1489-1501

Here we present the results of experiments investigating the adsorption of Protactinium and Thorium onto different particle types in natural seawater. Particle types studied were smectite as a representative of clay, biogenic opal from a cleaned diatom culture, manganese dioxide precipitate, and calcium carbonate. The particles were added to three different types of natural seawater (0.5 mg/L) which were first 0.2 μm-filtered, and the distribution of Pa and Th between dissolved and particulate phase (>0.2 μm) was monitored for 4 to 5 d at increasing time intervals. The tracers applied were the β-emitters ²³³Pa and ²³⁴Th. The measurement technique via β-counting for both nuclides in the same sample is reported here for the first time.The observed recoveries during the experiment range from 40 to 99 (±5) % for Th and from 51 to 105 (±6) % for Pa. The distribution coefficients (K_d) after establishment of an equilibrium cover a wide range for Th from 0.5 to 107 × 10⁶ ml/g, and from 0.03 to 166 × 10⁶ ml/g for Protactinium, depending on particle type and on the type of seawater used.Thorium revealed a specific affinity for all particle types investigated, with varying degree and adsorption kinetics. The results suggest that all particle types investigated may serve as Th carrier phases in the sediment. Pa was found to be less particle reactive than Th in most cases. Th/Pa fractionation factors (F_Th/Pa) were also obtained. Weakest fractionation was found on MnO₂ (F_Th/Pa=1), followed by the chemically cleaned biogenic opal (2.8) and smectite (5.4). The results for calcium carbonate were highly variable. Our experimental results imply that particle composition is indeed playing a role in the differing marine geochemistry of Th and Pa. We conclude that experiments with filtered natural seawater using particle concentrations on a natural level are a helpful approach when investigating the geochemical behaviour of strongly particle-reactive elements like Th and Pa in the marine environment.  相似文献   

Fiji: An encyclopaedic atlas     

Regina Scheyvens 《New Zealand geographer》2008,64(1):80-81

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Molecular and biochemical biomarkers responses in the mussel Mytilus edulis collected from Southern Brazil coast     

Rola RC  Monteiro Mda C  Reis SR  Sandrini JZ 《Marine pollution bulletin》2012,64(4):766-771

Marine ecosystems are typically subjected to a variety of stressors containing complex xenobiotics mixtures. This study aims to evaluate the responses of molecular and biochemical biomarkers in the mussel Mytilus edulis providing data for environmental monitoring programs development in Southern Brazil. Mussels were collected at a polluted site, near Patos Lagoon outfall, and at a control site. Gills, muscle and mantle samples were used for biomarker determinations. Mussels collected at the polluted site significantly increased superoxide dismutase (SOD) and glutathione S-transferase (GST) activities and decreased catalase (CAT) activity. Moreover, an increase in sod1, gstπ and hsp70 mRNA expression was observed. Overall, biochemical and molecular biomarkers responses were observed, but these responses varied depending on the analyzed tissue. These results indicate possible contaminants effects on organisms and the need for effective environmental monitoring programs in this ecosystem.  相似文献   

Development of a Matrix‐Matched Sphalerite Reference Material (MUL‐ZnS‐1) for Calibration of In Situ Trace Element Measurements by Laser Ablation‐Inductively Coupled Plasma‐Mass Spectrometry          下载免费PDF全文

Peter Onuk  Frank Melcher  Regina Mertz‐Kraus  Hans‐Eike Gäbler  Simon Goldmann 《Geostandards and Geoanalytical Research》2017,41(2):263-272

Sphalerite (ZnS) is an abundant ore mineral and an important carrier of elements such as Ge, Ga and In used in high‐technology applications. In situ measurements of trace elements in natural sphalerite samples using LA‐ICP‐MS are hampered by a lack of homogenous matrix‐matched sulfide reference materials available for calibration. The preparation of the MUL‐ZnS1 calibration material containing the trace elements V, Cr, Mn, Co, Ni, Cu, Ga, Ge, As, Se, Mo, Ag, Cd, In, Sn, Sb, Tl and Pb besides Zn, Fe and S is reported. Commercially available ZnS, FeS, CdS products were used as the major components, whereas the trace elements were added by doping with single‐element ICP‐MS standard solutions and natural mineral powders. The resulting powder mixture was pressed to pellets and sintered at 400 °C for 100 h using argon as an inert gas. To confirm the homogeneity of major and trace element distributions within the MUL‐ZnS1 calibration material, measurements were performed using EPMA, solution ICP‐MS, ICP‐OES and LA‐ICP‐MS. The results show that MUL‐ZnS‐1 is an appropriate material for calibrating trace element determination in sphalerite using LA‐ICP‐MS.  相似文献   

Reproductive seasonality of the fish fauna and limnoecology of semi-arid Brazilian reservoirs   总被引：1，自引：1，他引：0  

Sathyabama Chellappa  Regina M.X. Bueno  Thiago Chellappa  Naithirithi T. Chellappa  Vera Maria Fonseca Almeida e Val 《Limnologica》2009,39(4):325-329

The native fish fauna commonly found in the drainage basins of rivers and reservoirs of Latin America, including those of the semi-arid Northeastern Brazil, are representatives of the Neotropical region. This work reports on the reproductive ecology of five commercially important and consumable native fish species, in relation to rainfall and hydrological variables of the semi-arid reservoirs in Brazil. Pluviometric precipitation, temperature, pH, dissolved oxygen and electrical conductivity of the water were registered, and maturation of fish gonads was assessed on a monthly basis. This region is characterized with short spells of rain interspersed with long dry season and rainfall seems to be the main environmental factor which modulates the timing of the spawning period of fish. Construction of reservoirs without adequate facilities for fish migration has an adverse impact on the migratory fish species which are of commercial and ecological importance to semi-arid Northeastern Brazil.  相似文献   

Assessing drought in the drylands of northeast Brazil under regional warming exceeding 4 °C     

Marengo  Jose A.  Cunha  Ana Paula M. A.  Nobre  Carlos A.  Ribeiro Neto  Germano G.  Magalhaes  Antonio R.  Torres  Roger R.  Sampaio  Gilvan  Alexandre  Felipe  Alves  Lincoln M.  Cuartas  Luz A.  Deusdará  Karinne R. L.  Álvala  Regina C. S. 《Natural Hazards》2020,103(2):2589-2611

Natural Hazards - Historically, during periods of extreme drought, food security in the drylands of the semiarid region of Northeast Brazil (NEB) is under severe risk due to agricultural collapse....  相似文献   

H. VAN WOERDEN,R. J. ALLEN,W. B. BURTON (eds.): The Milky Way Galaxy. Proccedings of IAU Symposium No. 106. D. Reidel Publishing Company,Dordrecht, Boston. Lancester, 1985. 660 S. Preis: Dfl. 195.—. ISHN 90-277-1919-5     

Regina Schmidt 《Astronomische Nachrichten》1986,307(3):190-190

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