The Influence of NaBr/NaCl Ratio on the Br--Catalysed Production of Halogenated Radicals     

Wolfgang Behnke  Manfred Elend  Ulrich Krüger  Cornelius Zetzsch 《Journal of Atmospheric Chemistry》1999,34(1):87-99

The activation of Br^- and Cl^- to atomic Br and Cl in sea-spray aerosol was investigated in smog-chamber experiments. In the presence of O₃, hydrocarbons and NaCl aerosol alone no activation was observed. By adding Br^- to the aerosol, the chain reaction: Br + O₃ BrO, BrO + HO₂ HOBr, HOBr HOBr(aq), HOBr(aq) + H⁺ + Br^- Br₂ (6), HOBr(aq) + H⁺ + Cl^- BrCl (7) was verified. The step from reaction (6) to (7) is accompanied by a decrease of the Br^-/Cl^- ratio from 1/600 to less than 1/2000. In the absence of sulphate, the chain is initiated by the reaction of OH(aq) with Br^-. The pH value decreases to less than 2 during the first minutes of the experiment and later on to almost 1 (in the absence of NO_x or SO₂). This is caused by the formation of oxalic acid from alkanes and toluene. In stopped flow experiments, the reduction of Br₂ by oxalic acid was observed to occur through a two-step mechanism: HC₂O₄ ^- + Br₂ Br^- + BrC₂O₄H (k₂₂, k_-22), BrC₂O₄H Br^- + H⁺ + 2 CO₂ (23) with the following rate constants and ratios of rate constants, k ± 2: k₂₂k_-23 / k_-22 = (2.9 ± 0.3) · 10^-4 s^-1, k_-22 / k_-23 = 7000 ± ₃₀₀₀ ¹³⁰⁰⁰ M^-1, k₂₂ = 2 ±_-1 ⁴ M^-1 s^-1, and k_-23 > 0.1 s^-1, k_-22 > 600 M^-1 s^-1. Oxalic acid may be responsible for the inhibition of the chain reaction observed at the end of the experiments.  相似文献   

Die Eisabschmelzzeiten für die Ostsee östlich der Linie Trelleborg-Arkona und für den Finnischen und Rigaischen Meerbusen sowie für die südlichen Randbezirke der Bottensee     

Dipl.-Met. Ingrid Kühnel 《Ocean Dynamics》1968,21(1):15-20

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Die Eisvorbereitungszeiten für die Ostsee östlich der Linie Trelleborg—Arkona und für den Finnischen und Rigaischen Meerbusen sowie für die südlichen Randbezirke der Bottensee     

Ingrid Kühnel 《Ocean Dynamics》1967,20(1):1-6

Zusammenfassung Das langjährige Eisbeobachtungsmaterial der Ostseeanliegerstaaten gestattet die Bestimmung der Eisvorbereitungszeit in Abhängigkeit von der Lufttemperatur nach dem Verfahren von F. Nusser [1950] in leicht abgewandelter Form (Tabellen 1–7 und Abbildungen 1–4 u. 6). Die Eisbildung setzt an der gegliederten Nordküste des Finnischen Meerbusens und entlang des Stockholmer Schärengebietes schon nach einer Woche ein, während an der wenig gegliederten estnischen Küste und der schwedischen Südküste mindestens 10 Tage mehr zur Eisbildung erforderlich sind. Die Eisvorbereitungszeiten nehmen seewärts zu und erreichen auf offener See Werte von mehr als 40 Tagen; nach 30 Tagen ist der zentrale Teil des Finnischen Meerbusens mit Eis bedeckt. Im gleichen Zeitraum beschränkt sich die Eisbildung in der nördlichen und mittleren Ostsee auf einen schmalen Küstenstreifen.

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The Eisvorbereitungszeiten (number of consecutive days with negative mean air temperatures prior to the first occurrence of ice) in the Baltic Sea east of the Trelleborg—Arkona line, in the Gulfs of Finland and Riga, and in the southern areas of the Gulf of Bothnia

Summary The ice observational material collected over long years by the states bordering the Baltic Sea permits to determine the Eisvorbereitungszeit in dependence on the air temperature after the method of F. Nusser [1950] slightly modified (Tables 1–7 and Figs. 1–4, 6). The generation of ice at the rugged north coast of the Gulf of Finland and along the Stockholm skerries starts after one week already, while at the less rugged Estonian coast and at the south coast of Sweden at least 10 days more are required for the formation of ice. The Eisvorbereitungszeiten increase in the direction of the sea and attain values of more than 40 days in the open sea; after 30 days the central part of the Gulf of Finland is covered with ice. In the same period of time the formation of ice in the northern and central Baltic is restricted to a narrow coastal strip.

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Temps de formation des glaces dans la mer Baltique à l'Est de la ligne Trelleborg—Arkona, dans les golfes de Finlande et de Riga ainsi que dans les zones riveraines sud de la partie sud du golfe de Botnie

Résumé Les observations des glaces effectuées au cours de nombreuses années par les états riverains de la mer Baltique permettent de déterminer le temps de formation des glaces en fonction de la température de l'air suivant la méthode de F. Nusser [1950] légèrement modifiée (Tableaus 1 à 7 et Fig. 1 à 4 et 6). Le long de la côte nord du golfe de Finlande, encombrée d'îlots, et le long de la zone des Skärs de Stockholm, la glace se forme déjà au bout d'une semaine; tandis que le long de la côte d'Estonie, peu encombrée, et de la côte sud de Suède, il faut au moins 10 jours de plus pour qu'il y ait formation de glace. Les temps de formation augmentent vers le large et dépassent 40 jours en pleine mer; la partie centrale du golfe de Finlande est couverte de glace au bout de 30 jours. Pour un même temps, la formation de glace dans la Baltique nord et centrale se limite à un étroit ruban côtier.

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Regulations concerning risk analysis and their application in environmental safety protection in Norway     

Ingrid   rstad 《Marine pollution bulletin》1994,29(6-12):330-333

The Norwegian Petroleum Directorate (NPD), together with the State Pollution Control Authorities, administers the regulations concerning the implementation and use of risk analyses in petroleum activities.

This paper presents the main requirements contained in the Norwegian regulations concerning risk analyses, and focuses on their interaction with the legislation concerning safety for people, the environment, assets and financial interests.

In this context the NPD emphasizes the authorities' expectations with regard to the use of risk analyses in the management of risks to the environment, especially when conducting petroleum activities in environmentally vulnerable areas on the Norwegian continental shelf.  相似文献   

Geochronology and Nd-Sr systematics of Lusatian granitoids: significance for the evolution of the Variscan orogen in east-central Europe     

A. Kröner  E. Hegner  J. Hammer  G. Haase  K. -H. Bielicki  M. Krauss  J. Eidam 《International Journal of Earth Sciences》1994,83(2):357-376

A variety of pre-Variscan granitoids and two Variscan monzogranites occurring in the central and western parts of the Lusatian Granodiorite Complex (LGC), Saxonia were dated by the single zircon evaporation method, complemented by whole rock Nd isotopic data and Rb-Sr whole rock and mineral ages. The virtually undeformed pre-Variscan granitoids constitute a genetically related, mostly peraluminous magmatic suite, ranging in composition from two-mica granodiorite, muscovitebearing biotite quartz diorite (tonalite) and granodiorite to biotite granodiorite and monozogranite. ²⁰⁷Pb/²⁰⁶Pb isotopic ratios derived from the evaporation of single zircons separated from 13 samples representing the above rock types display complex spectra which document significant involvement of late Archaean to late Proterozoic continental crust in the generation of the granitoid melts. Mean ²⁰⁷/Pb/²⁰⁶Pb ages for zircons considered to reflect the time of igneous emplacement range between 542 ± 9 and 587 ± 17 Ma, typical of the Cadomian event elsewhere in Europe, whereas zircon xenocrysts yielded ages between 706 ± 13 and 2932 ± Ma. Detrital zircons from greywackes intruded by the granitoids and found as xenoliths in them provided ages between 1136 ± 22 and 2 574 ± Ma. Rb-Sr whole rock data display good to reasonable linear arrays that, with one exception, correspond to the emplacement ages established for the zircons. Two post-tectonic Variscan monzogranites yielded identical ²⁰⁷/Pb/²⁰⁶Pb single zircon ages of 304 ± 14 Ma and record the end of Variscan granitoid activity in the LGC.The variations in Nd and Sr isotopic data of the Cadomian granitoids are consistent with an origin through the melting and mixing of Archean to early Proterozoic crust with variable proportions of mantle-derived, juvenile magmas. Such mixing may have occurred at the base of an active continental margin or in an intraplate setting through plume-related magmatic underplating. The LGC is interpreted here as a Cadomian (Pan-African) terrane distinct from adjacent Variscan and pre-Variscan domains, the origin of which remains obscure and which probably became involved in Palaeozoic terrane accretion late in the Variscan event.  相似文献   

Limnological response to the Laacher See eruption (LSE) in an annually laminated Allerød sediment sequence from the Nahe palaeolake,northern Germany     

Stefan Dreibrodt  Sascha Krüger  Jan Weber  Ingo Feeser 《Boreas: An International Journal of Quaternary Research》2021,50(1):167-183

This paper presents evidence for a limnological response to the Laacher See eruption (LSE) as detected in lake sediments from Nahe, northern Germany. The sediment section of the Allerød period dating to between 13 422 and 12 708 cal. a BP is preserved in annual laminations. Within this section, the LSE was identified as a cryptotephra layer (12 944±44 cal. a BP). Microfacies analysis, continuous high-resolution geochemical measurements and pollen analyses enabled a high-resolution reconstruction of environmental change. The older part of the Allerød (c. 13 422 to 12 943 cal. a BP) was characterized by relatively stable sedimentation conditions. Evidence for windier conditions dating to c. 13 160 to 13 080 cal. a BP probably reflects the Gerzensee oscillation. Pronounced changes of the lake sedimentation followed the LSE. Four unusually thick varves with increased amounts of allochthonous material indicate serious disturbance of the local environment immediately after the LSE, related to increased storminess and/or the occurrence of high intensity rainfall events. A pronounced reduction of biogenic silica accumulation for c. 60 years after the LSE could reflect a period of acidification. Indications of a simultaneous lake level increase until c. 60 years after the LSE are in line with the supposed reduced evapotranspiration associated with cooler conditions. About 120 years after the LSE, increased oxygen access at the lake bottom, allochthonous input and Cl fluxes point to an onset of increasingly stronger westerly winds, probably as a long-term response to the LSE. This supports the idea of a southward shift of the mid-latitude westerlies wind system within the interval between the LSE and the beginning of the Younger Dryas. The pace of the southwards shift of this wind system decreased from 10 km a⁻¹ in the initial phase (40–120 years after LSE) to 6 km a⁻¹ in the later phase (120–200 years after LSE).  相似文献   

Estimating Preferential Flow in Karstic Aquifers Using Statistical Mixed Models     

Angel A. Anaya  Ingrid Padilla  Raul Macchiavelli  Dorothy J. Vesper  John D. Meeker  Akram N. Alshawabkeh 《Ground water》2014,52(4):584-596

Karst aquifers are highly productive groundwater systems often associated with conduit flow. These systems can be highly vulnerable to contamination, resulting in a high potential for contaminant exposure to humans and ecosystems. This work develops statistical models to spatially characterize flow and transport patterns in karstified limestone and determines the effect of aquifer flow rates on these patterns. A laboratory‐scale Geo‐HydroBed model is used to simulate flow and transport processes in a karstic limestone unit. The model consists of stainless steel tanks containing a karstified limestone block collected from a karst aquifer formation in northern Puerto Rico. Experimental work involves making a series of flow and tracer injections, while monitoring hydraulic and tracer response spatially and temporally. Statistical mixed models (SMMs) are applied to hydraulic data to determine likely pathways of preferential flow in the limestone units. The models indicate a highly heterogeneous system with dominant, flow‐dependent preferential flow regions. Results indicate that regions of preferential flow tend to expand at higher groundwater flow rates, suggesting a greater volume of the system being flushed by flowing water at higher rates. Spatial and temporal distribution of tracer concentrations indicates the presence of conduit‐like and diffuse flow transport in the system, supporting the notion of both combined transport mechanisms in the limestone unit. The temporal response of tracer concentrations at different locations in the model coincide with, and confirms the preferential flow distribution generated with the SMMs used in the study.  相似文献   

Dependence of air pollution on meteorological conditions based on magnetic susceptibility measurements: a case study from Warsaw     

Beata Górka-Kostrubiec  El?bieta Król  Maria Jeleńska 《Studia Geophysica et Geodaetica》2012,56(3):861-877

This study reports systematic analysis of air pollution concentration by particulate matter (PM) in relation to annual changes of metrological conditions. The concentration of PM collected on filters was evaluated by magnetic properties. Long series of filters collected during 1977, 1980, 1981 and 1985 in Warsaw have been used for measurement. Such long time series allowed a better determination of correlation between seasonal susceptibility changes and meteorological conditions and to verify the repeatability of annual behavior. The magnetic susceptibility normalized by mass (??) has been used as a proxy of pollution. Monthly variations of ?? (??_m) demonstrated slow and small seasonal changes disturbed by quick, high peaks. The filters with high susceptibilities contain a mixture of magnetic single and multidomain grains which is characteristic for anthropogenic pollution, with the frequency-dependent susceptibility ??_fd being less than 4%. The low susceptibility samples are characterized by admixture of small amount of pseudo-single domain (PSD) and possible small amount of superparamagnetic (SP) grains. Detailed analysis of reduced mean monthly susceptibility ??_R revealed that temperature and absolute humidity correlate positively in cold period of year and negatively in warm months. The linear correlation coefficients range from 0.7 to 0.9 and from 0.3 to 0.4 for negative and positive linear correlation, respectively. The dispersion of pollutants in a city depends on the way of ventilation. The big cities like Warsaw are urban heat islands which act the most effective way for the warm period and for the cold time. The correlation of ??_R with absolute humidity is similar to that for temperature but for different reasons. The presence of big amount of water vapor particles in the atmosphere can favor the adhesion of smaller ferromagnetic grains to their surface which can accelerate the process of falling down of such agglomerates. Such a process can take place during wintertime. We do not observe clear correlation between ??_R and precipitation.  相似文献   

Environmental and social recovery asymmetries to large-scale disturbances in small island communities     

Aswani  Shankar  van Putten  Ingrid  Miñarro  Sara 《Natural Hazards》2017,86(1):241-262

Natural Hazards - People’s livelihoods in tropical small-island developing states are greatly dependent on marine ecosystem services. Yet services such as fisheries and coastal buffering are...  相似文献   

Palaeozoic evolution of the North Tianshan based on palaeomagnetic data – transition from Gondwana towards Pangaea     

U. Kirscher  V. Bachtadse  A. V. Mikolaichuk  A. Kröner  D. V. Alexeiev 《International Geology Review》2017,59(16):2003-2020

We present new palaeomagnetic data for Cambrian and Ordovician volcanic and sedimentary rocks from the Kyrgyz North Tianshan (NTS) and review available data from the southwestern Central Asian Orogenic Belt (CAOB) to elucidate the tectonic history and evolution of this region during the early Palaeozoic. We observed a coherent evolution of the NTS and the Kazakhstan continent (or Kazakhstania) with a constant northwards movement between the Cambrian and Devonian at ～5 cm/a. After the northwards movement ceased in the Devonian, the accreted terrane assemblage of Kazakhstania occupied a stable latitudinal position at ～30°N until the final amalgamation of Eurasia occurred in the late Carboniferous to early Permian. Amalgamation of the Tarim and Turan blocks caused a counterclockwise bending within the southwestern segment of the CAOB, which occurred in an inconsistent way by a brittle-like response of the upper crust with a large variety of rotational movement. We suggest an evolution of the Kyrgyz CAOB terranes by steady migration away from Gondwana and subsequent capture in a zone of global downwelling at ~30°N, where accretion and subsequent amalgamation of Eurasia occurred with the CAOB terranes in its centre.  相似文献