Measurements of CO,HCN, and C2H6 Total Columns in Smoke Plumes Transported from the 2010 Russian Boreal Forest Fires to the Canadian High Arctic     

C. Viatte  K. Strong  C. Paton-Walsh  J. Mendonca  N. T. O'Neill  J. R. Drummond 《大气与海洋》2013,51(5):522-531

In August 2010, simultaneous enhancements of aerosol optical depth and total columns of carbon monoxide (CO), hydrogen cyanide (HCN), and ethane (C₂H₆) were observed at the Polar Environment Atmospheric Research Laboratory (PEARL, 80.05°N, ?86.42°W, 0.61 km above sea level, Eureka, Nunavut, Canada). Moderate Resolution Imaging Spectroradiometer (MODIS) hot spots, Ozone Monitoring Instrument (OMI) aerosol index maps, and Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) back-trajectories were used to attribute these enhancements to an intense boreal fire event occurring in Russia. A ground-based Fourier Transform InfraRed (FTIR) spectrometer at PEARL provided vertically integrated measurements of trace gases transported in smoke plumes. We derived HCN and C₂H₆ equivalent emission ratios with respect to CO of 0.0054?±?0.0022 and 0.0108?±?0.0036, respectively, and converted them into equivalent emission factors of 0.66?±?0.27 g kg^?1 and 1.47?±?0.50 g kg^?1 (in grams of gas per kilogram of dry biomass burnt, with one-sigma uncertainties). These emission factors add new observations to the relatively sparse datasets available and can be used to improve the simulation of biomass burning fire emissions in chemical transport models. These emission factors for the boreal forest are in agreement with the mean values recently reported in a compilation study.  相似文献   

Structural controls on groundwater flow in a fractured bedrock aquifer underlying an agricultural region of northwestern New Brunswick,Canada     

Aaron DesRoches  Serban Danielescu  Karl Butler 《Hydrogeology Journal》2014,22(5):1067-1086

A hydrogeological study was conducted in northwestern New Brunswick, Canada, to improve the predictability of fracture-dominated groundwater flow within folded bedrock composed of fine-grained turbidites. Borehole televiewer logging and outcrop mapping, integrated with hydraulic packer tests revealed enhanced hydraulic conductivity associated with northeasterly striking bedding-plane fractures formed during folding and flexural slip. These fractures impart azimuthal anisotropy to the aquifer because of moderately dipping fold limbs. High-angle fractures form a well-developed non-stratabound network, comprising two open fracture sets striking NNE parallel to the current direction of principal stress, and WNW parallel to the direction of principal stress that dominated during the Acadian orogeny. The subset of fractures showing significant oxidation, deemed most important to the groundwater flow system, is dominated by bedding-plane and high-angle fractures striking near-parallel to the maximum principal stress direction, resulting in extensional opening and enhanced hydraulic conductivities. An equivalent porous media model, incorporating anisotropy and varying hydraulic conductivity with depth, indicates that horizontal flow dominates the aquifer with relatively minor exchange between different model layers. These findings have implications for understanding flow directions in the Black Brook Watershed and elsewhere in the Matapédia Basin where fractures formed under similar stress conditions.  相似文献   

Detection and discrimination of sulfate minerals using reflectance spectroscopy   总被引：1，自引：0，他引：1  

Edward A. Cloutis  Frank C. Hawthorne  Katherine Krenn  Dionne Marcino  Johnathon Strong  Diana L. Blaney  Faith Vilas 《Icarus》2006,184(1):121-157

A suite of sulfate minerals were characterized spectrally, compositionally, and structurally in order to develop spectral reflectance-compositional-structural relations for this group of minerals. Sulfates exhibit diverse spectral properties, and absorption-band assignments have been developed for the 0.3-26 μm range. Sulfate absorption features can be related to the presence of transition elements, OH, H₂O, and SO₄ groups. The number, wavelength position, and intensity of these bands are a function of both composition and structure. Cation substitutions can affect the wavelength positions of all major absorption bands. Hydroxo-bridged Fe³⁺ results in absorption bands in the 0.43, 0.5, and 0.9 μm regions, while the presence of Fe²⁺ results in absorption features in the 0.9-1.2 μm interval. Fundamental SO bending and stretching vibration absorption bands occur in the 8-10, 13-18, and 19-24 μm regions (1000-1250, 550-770, and 420-530 cm⁻¹). The most intense combinations and overtones of these fundamentals are found in the 4-5 μm (2000-2500 cm⁻¹) region. Absorption features seen in the 1.7-1.85 μm interval are attributable to HOH/OH bending and translation/rotation combinations, while bands in the 2.1-2.7 μm regions can be attributed to H₂O- and OH-combinations as well as overtones of SO bending fundamentals. OH- and H₂O-bearing sulfate spectra are fundamentally different from each other at wavelengths below ∼6 μm. Changes in H₂O/OH content can shift SO band positions due to change in bond lengths and structural rearrangement. Differences in absorption band wavelength positions enable discrimination of all the sulfate minerals used in this study in a number of wavelength intervals. Of the major absorption band regions, the 4-5 μm region seems best for identifying and discriminating sulfates in the presence of other major rock-forming minerals.  相似文献   

Shocked monazite chronometry: integrating microstructural and in situ isotopic age data for determining precise impact ages   总被引：1，自引：0，他引：1  

Timmons?M.?EricksonEmail authorView author&#;s OrcID profile  Nicholas?E.?Timms  Christopher?L.?Kirkland  Eric?Tohver  Aaron?J.?Cavosie  Mark?A.?Pearce  Steven?M.?Reddy 《Contributions to Mineralogy and Petrology》2017,172(2-3):11

Monazite is a robust geochronometer and occurs in a wide range of rock types. Monazite also records shock deformation from meteorite impact but the effects of impact-related microstructures on the U–Th–Pb systematics remain poorly constrained. We have, therefore, analyzed shock-deformed monazite grains from the central uplift of the Vredefort impact structure, South Africa, and impact melt from the Araguainha impact structure, Brazil, using electron backscatter diffraction, electron microprobe elemental mapping, and secondary ion mass spectrometry (SIMS). Crystallographic orientation mapping of monazite grains from both impact structures reveals a similar combination of crystal-plastic deformation features, including shock twins, planar deformation bands and neoblasts. Shock twins were documented in up to four different orientations within individual monazite grains, occurring as compound and/or type one twins in (001), (100), \(\left( 10\bar{1} \right)\), \(~\{110\}\), \(\left\{ 212 \right\},\) and type two (irrational) twin planes with rational shear directions in \([0\bar{1}\bar{1}]\) and \([\bar{1}\bar{1}0]\). SIMS U–Th–Pb analyses of the plastically deformed parent domains reveal discordant age arrays, where discordance scales with increasing plastic strain. The correlation between discordance and strain is likely a result of the formation of fast diffusion pathways during the shock event. Neoblasts in granular monazite domains are strain-free, having grown during the impact events via consumption of strained parent grains. Neoblastic monazite from the Inlandsee leucogranofels at Vredefort records a ²⁰⁷Pb/²⁰⁶Pb age of 2010?±?15 Ma (2σ, n?=?9), consistent with previous impact age estimates of 2020 Ma. Neoblastic monazite from Araguainha impact melt yield a Concordia age of 259?±?5 Ma (2σ, n?=?7), which is consistent with previous impact age estimates of 255?±?3 Ma. Our results demonstrate that targeting discrete microstructural domains in shocked monazite, as identified through orientation mapping, for in situ U–Th–Pb analysis can date impact-related deformation. Monazite is, therefore, one of the few high-temperature geochronometers that can be used for accurate and precise dating of meteorite impacts.  相似文献