Evaluation of the use of photochemical indicators to assess ozone—NOx—VOC sensitivity in the Southwestern Iberian Peninsula     

Nuria Castell  Ariel F. Stein  Enrique Mantilla  Rosa Salvador  Millán Millán 《Journal of Atmospheric Chemistry》2009,63(1):73-91

Understanding the chemical links between ozone (O₃) and its two main precursors, nitrogen oxides (NOx) and volatile organic compounds (VOC), is important for designing effective photochemical smog reduction strategies. This chemical relationship will determine which precursor (NOx or VOC) emission reduction will be more effective for decreasing the ozone formation. Under certain conditions, ozone levels decrease as a result of a reduction in NOx emissions but do not respond significantly to changes in VOC emissions (NOx-sensitive condition), while under other conditions ozone concentrations decrease in response to reductions in VOCs and may even increase when NOx emissions are reduced (VOC-sensitive conditions). Indicator species can be used to assess the sensitivity of ozone to changes in the emissions of its precursors. These indicators are species or species ratios involved in ozone photochemistry which reflect the primary chemical process through which the ozone was formed. In this work we use the MM5-CAMx model system to explore the behaviour of various indicator species during two meteorological situations featuring different atmospheric conditions in a complex terrain area. The results show that indicators based on nitrogen compounds (i.e,. NOy and NOz) are suitable for defining the transition range from VOC- to NOx-sensitive chemistry, and that despite the uncertainties associated with the use of chemical indicators, the ratios O₃/NOy and O₃/NOz may provide a simple and useful way to summarize the response of ozone to changes in NOx and VOC emissions in Southwestern Spain.  相似文献   

Propagation of the Storegga tsunami into ice‐free lakes along the southern shores of the Barents Sea     

Anders Romundset  Stein Bondevik 《第四纪科学杂志》2011,26(5):457-462

Deposits in coastal lakes in northernmost Norway reveal that the Storegga tsunami propagated well into the Barents Sea ca. 8100–8200 years ago. A tsunami deposit – found in cores from five coastal lakes located near the North Cape in Finnmark – rests on an erosional unconformity and consists of graded sand layers and re‐deposited organic remains. Rip‐up clasts of lake mud, peat and soil suggest strong erosion of the lake floor and neighbouring land. Inundation reached at least 500 m inland and minimum vertical run‐up has been reconstructed to 3–4 m. In this part of the Arctic coastal lakes are usually covered by >1 m of solid lake ice in winter. The significant erosion and deposition of rip‐up clasts indicate that the lakes were ice free and that the ground was probably not frozen. We suggest that the Storegga slide and ensuing tsunami happened sometime in the summer season, between April and October. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Varve counting reveals high resolution radiocarbon reservoir age variations in palaeolake Lisan     

Sushma Prasad  J. F. W. Negendank  Mordechai Stein 《第四纪科学杂志》2009,24(7):690-696

The laminated lacustrine sediments deposited in the last glacial Lake Lisan represent annual deposits of primary aragonite and silty detritus that reflect the annual supply of bicarbonate‐bearing freshwater to the lake. A varve‐counting curve was constructed for the time interval of ca. 17.4–22 cal. ka BP based on aragonite U/Th, and atmospheric radiocarbon ages of organic debris recovered from the studied section. Radiocarbon in the primary (evaporitic) aragonite comprises both atmospheric and old carbon (reflecting the reservoir age). The aragonite reservoir ages were determined by comparing the aragonite radiocarbon dates to the varve counting curve, and are found to lie in the range 1900–600 a and display a continuous decline. This opens the possibility for high (annual) resolution monitoring of the reservoir age, similar in quality to tree ring counting, during the upper part of Marine Isotope Stage (MIS) 2. Our work also demonstrates that a ‘uniform’ reservoir age correction is inappropriate when determining the chronology of short‐term climate events in lacustrine environments. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Report of Investigation on — GROUND-WATER CONTAMINATION POTENTIAL AT 21 INDUSTRIAL WASTE-WATER IMPOUNDMENTS IN OHIO     

Russell B. Stein  John A. Noyes 《Ground water》1981,19(1):70-80

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The 1966 Kremasta reservoir earthquake sequence     

Seth Stein  Douglas A. Wiens  Kazuya Fujita 《Earth and Planetary Science Letters》1982,59(1):49-60

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Diagenetic effects on the distribution of uranium in live and Holocene corals from the Gulf of Aqaba     

Boaz Lazar  Rivka Enmar  Miriam Bar-Matthews  Mordechai Stein 《Geochimica et cosmochimica acta》2004,68(22):4583-4593

We investigated the effects of diagenetic alteration (dissolution, secondary aragonite precipitation and pore filling) on the distribution of U in live and Holocene coral skeletons. For this, we drilled into large Porites lutea coral-heads growing in the Nature Reserve Reef (NRR), northern Gulf of Aqaba, a site close to the Marine Biology Laboratory, Elat, Israel, and sampled the core material and porewater from the drill-hole. In addition, we sampled Holocene corals and beachrock aragonite cements from a pit opened in a reef buried under the laboratory grounds. We measured the concentration and isotopic composition of U in the coral skeletal aragonite, aragonite cements, coral porewater and open NRR and Gulf of Aqaba waters.Uranium concentration in secondary aragonite filling the skeletal pores is significantly higher than in primary biogenic aragonite (17.3 ± 0.6 compared to 11.9 ± 0.3 nmol · g⁻¹, respectively). This concentration difference reflects the closed system incorporation of uranyl tri-carbonate into biogenic aragonite with a U/Ca bulk distribution coefficient (K_D) of unity, versus the open system incorporation into secondary aragonite with K_D of 2.4. The implication of this result is that continuous precipitation of secondary aragonite over ∼1000 yr of reef submergence would reduce the coral porosity by 5% and can produce an apparent lowering of the calculated U/Ca - SST by ∼1°C and apparent age rejuvenation effect of 7%, with no measurable effect on the calculated initial U isotopic composition.All modern and some Holocene corals (with and without aragonite cement) from Elat yielded uniform δ²³⁴U = 144 ± 5, similar to the Gulf of Aqaba and modern ocean values. Elevated δ²³⁴U values of ∼180 were measured only in mid-Holocene corals (∼5000 yr) from the buried reef. The values can reflect the interaction of the coral skeleton with ²³⁴U-enriched ground-seawater that washes the adjacent granitic basement rocks.We conclude that pore filling by secondary aragonite during reef submergence can produce small but measurable effects on the U/Ca thermometry and the U-Th ages. This emphasizes the critical importance of using pristine corals where the original mineralogy and porosity are preserved in paleooceanographic tracing and dating.  相似文献   

Re–Os molybdenite dating of granite-related Sn–W–Mo mineralisation at Hnilec, Gemeric Superunit, Slovakia     

M. Kohút  H. Stein 《Mineralogy and Petrology》2005,85(3-4):117-129

Summary Re–Os molybdenite ages from the exocontact of the Hnilec granite-greisen body provide temporal constraints for tin, tungsten and molybdenite mineralisation in the Gemeric Superunit, Slovakia. Two molybdenite separates were taken from a representative sample of the Sn–W–Mo mineralisation at Hnilec and their Re–Os ages of 262.2 ± 0.9 and 263.8 ± 0.8 Ma (2-sigma) are in excellent agreement. The obtained Re–Os molybdenite ages are similar to recent but less precise electron microprobe monazite (276 ± 13 Ma) and U–Pb single zircon (250 ± 18 Ma) ages from the Hnilec granite intrusion, supporting a granite-related greisen origin for the Sn–W–Mo mineralisation. Our precise Re–Os molybdenite ages resolve the long time controversy over the timing of high-temperature mineralisation in the Gemeric Superunit. These Permian ages eliminate suggestions of an Alpine age. The sulphur isotope composition of the studied molybdenite is δ³⁴S_(CDT) = 1.71 ± 0.2‰ and is consistent with a magmatic sulphur source. Field observations indicate the lack of a broad contact aureole in the vicinity of the Hnilec granite body. Shallow level granite emplacement in schistose host rocks was accompanied by alteration and formation of tin-tungsten greisen in the upper part of the granite and exocontact molybdenite mineralisation, both commonly lacking in other granite bodies within the Gemeric Superunit.  相似文献   

The geology and Re–Os geochronology of the Palaeoproterozoic Vaikijaur Cu–Au–(Mo) porphyry-style deposit in the Jokkmokk granitoid, northern Sweden     

Christina Lundmark  Holly Stein  Pär Weihed 《Mineralium Deposita》2005,40(4):396-408

The Vaikijaur Cu–Au–(Mo) deposit is located in the ca. 1.88 Ga calc-alkaline Jokkmokk granitoid near the Archaean–Proterozoic palaeoboundary within the Fennoscandian shield of northern Sweden. The Skellefte VMS district lies immediately to the south and the northern Norrbotten Fe-oxide–Cu–Au deposits to the north. The Vaikijaur deposit occupies an area of 2×3 km within the Jokkmokk granitoid and includes stockwork quartz-sulphide veinlets and disseminated chalcopyrite, pyrite, gold, molybdenite, magnetite, and pyrrhotite. Porphyritic mafic dykes were emplaced along fractures in a ring dyke pattern. The Jokkmokk granitoid, dykes, and the mineralized area are foliated, indicating that mineralization predated the main regional deformation. The mineralized area is characterized by strong potassic alteration. Phyllic and propylitic alteration zones are also present. A pyrite-rich inner core is surrounded by a concentric zone with pyrite, chalcopyrite, and gold. Molybdenite is distributed irregularly throughout the chalcopyrite zone. Geophysical data indicate a strongly conductive central zone in the mineralized area bordered by conductive and high magnetic zones. Five high precision Re–Os age determinations for three molybdenite occurrences from outcrop and drill core samples constrain the age of porphyry-style Cu–Au–(Mo) mineralization to between 1889±10 and 1868±6 Ma. A younger molybdenite is associated with a much later metamorphic event at about 1750 Ma. These data suggest that primary porphyry-style mineralization was associated with calc-alkaline magmatism within the Archaean–Proterozoic boundary zone at ca. 1.89–1.87 Ga.  相似文献   

The 2004 Sumatra earthquake and Indian Ocean tsunami: What happened and why?     

Seth Stein  Emile A. Okal 《Visual Geosciences》2005,10(1):21-26

The December 26, 2004 Sumatra earthquake and the tsunami that followed killed over 300,000 people. In this paper, we analyze and discuss the geologic causes for this earthquake, the mechanisms that generated it, and follow up with a discussion on ways to prevent this type of disaster in the future.  相似文献   

Re-Os ages for Archean molybdenite and pyrite, Kuittila-Kivisuo, Finland and Proterozoic molybdenite, Kabeliai, Lithuania: testing the chronometer in a metamorphic and metasomatic setting   总被引：9，自引：0，他引：9  

H. J. Stein  K. Sundblad  R. J. Markey  J. W. Morgan  G. Motuza 《Mineralium Deposita》1998,33(4):329-345

Seven ¹⁸⁷Re-¹⁸⁷Os ages were determined for molybdenite and pyrite samples from two well-dated Precambrian intrusions in Fennoscandia to examine the sustainability of the Re-Os chronometer in a metamorphic and metasomatic setting. Using a new ¹⁸⁷Re decay constant (1.666 × 10⁻¹¹y⁻¹) with a much improved uncertainty (±0.31%), we determined replicate Re-Os ages for molybdenite and pyrite from the Kuittila and Kivisuo prospects in easternmost Finland and for molybdenite from the Kabeliai prospect in southernmost Lithuania. These two localities contain some of the oldest and youngest plutonic activity in Fennoscandia and are associated with newly discovered economic Au mineralization (Ilomantsi, Finland) and a Cu-Mo prospect (Kabeliai, Lithuania). Two Re-Os ages for vein-hosted Kabeliai molybdenite average 1486 ± 5 Ma, in excellent agreement with a 1505 ± 11 Ma U-Pb zircon age for the hosting Kabeliai granite pluton. The slightly younger age suggests the introduction of Cu-Mo mineralization by a later phase of the Kabeliai magmatic system. Mean Re-Os ages of 2778 ± 8 Ma and 2781 ± 8 Ma for Kuittila and Kivisuo molybdenites, respectively, are in reasonable agreement with a 2753 ± 5 Ma weighted mean U-Pb zircon age for hosting Kuittila tonalite. These Re-Os ages agree well with less precise ages of 2789 ± 290 Ma for a Rb-Sr whole-rock isochron and 2771 ± 75 Ma for the average of six Sm-Nd T_DM model ages for Kuittila tonalite. Three Re-Os analyses of a single pyrite mineral separate, from the same sample of Kuittila pluton that yielded a molybdenite separate, provide individual model ages of 2710 ± 27, 2777 ± 28, and 2830 ± 28 Ma (Re = 17.4, 12.1, and 8.4 ppb, respectively), with a mean value of 2770 ± 120 Ma in agreement with the Kuittila molybdenite age. The Re and ¹⁸⁷Os abundances in these three pyrite splits are highly correlated (r = 0.9994), and provide a ¹⁸⁷Re-¹⁸⁷Os isochron age of 2607 ± 47 Ma with an intercept of 21 ppt ¹⁸⁷Os (MSWD = 1.1). It appears that the Re-Os isotopic system in pyrite has been reset on the millimeter scale and that the 21 ppt ¹⁸⁷Os intercept reflects the in situ decay of ¹⁸⁷Re during the ∼160 to 170 m.y. interval from ∼2778 Ma (time of molybdenite ± pyrite deposition) to ∼2607 Ma (time of pyrite resetting). When the Re-Os data for molybdenites from the nearby Kivisuo prospect are plotted together with the Kuittila molybdenite and pyrite data, a well-constrained five-point isochron with an age of 2780 ± 8 Ma and a ¹⁸⁷Os intercept (−2.4 ± 3.8 ppt) of essentially zero results (MSWD = 1.5). We suggest that the pyrite isochron age records a regional metamorphic and/or hydrothermal event, possibly the time of Au mineralization. A proposed Re-Os age of ∼2607 Ma for Au mineralization is in good agreement with radiometric ages by other methods that address the timing of Archean Au mineralization in deposits worldwide (so-called “late Au model”). Molybdenite, in contrast, provides a robust Re-Os chronometer, retaining its original formation age of ∼2780 Ma, despite subsequent metamorphic disturbances in Archean and Proterozoic time. Received: 25 September 1996 / Accepted: 27 August 1997  相似文献