Model analysis of the measured concentration of organic gases in the Norwegian Arctic

A 2-D meridional model for the chemistry and transport in the troposphere is used to study the seasonal variation of the concentration of organic gases like C₂H₂, C₂H₆, C₃H₈, C₆H₆, C₇H₈. CHCl₃ and C₂Cl₄ at high latitudes. The anthropogenic sources for these species were estimated, and the temporal and latitudinal distribution of OH and O₃ was calculated using a complex photochemical reaction system. There is fair agreement between the calculated annual variation and the measured concentrations for C₂H₂, C₂H₆, C₃H₈, C₇H₈ and C₂Cl₄ at Spitsbergen during July 1982 and March/April 1983, with a distinct late winter maximum and summer minimum. For CHCl₃, the direct anthropogenic source is minor compared to indirect anthropogenic or natural sources. For benzene, emission in car exhaust is important, but other anthropogenic sources are required for the calculations to agree with the measurements. Measured C₂H₄ and C₃H₆ concentrations are much higher than the calculated ones based on anthropogenic emissions, and show opposite seasonal trends. This indicates biogenic sources for these compounds.A buildup of PAN (300 pptv) is calculated at high latitudes during winter. This makes it the dominant source for NO_x as the temperature increases in the spring. NO_x is found to be a limiting factor for O₃ production at high latitudes during spring.     

Ore metal redistribution by hydrocarbon–brine and hydrocarbon–halide melt phases, North Range footwall of the Sudbury Igneous Complex, Ontario, Canada

We report methane-dominant hydrocarbon (fluid) inclusions (CH₄±C₂H₆–C₂H₂, C₃H₈) coexisting with primary brine inclusions and secondary halide melt (solid NaCl) inclusions in Au–Pt-rich quartz-sulfide-epidote alteration veins associated with the footwall-style Cu–PGE (platinum-group element)–Au deposits at the Fraser Mine (North Range of the Sudbury Igneous Complex). Evidence for coentrapment of immiscible hydrocarbon–brine, and hydrocarbon–halide melt mixtures is demonstrated. A primary CH₄–brine assemblage was trapped during quartz growth at relatively low T (min. T _trapping∼145–315°C) and P (max. P _trapping∼500 bar), prior to the crystallization of sulfide minerals in the veins. Secondary inclusions contain solid halite and a mixture of CH₄, C₂H₆–C₂H₂ and C₃H₈ and were trapped at a minimum T of ∼710°C. The halite inclusions may represent halide melt that exsolved from crystallizing sulfide ores that texturally postdate (by replacement) early alteration quartz hosting the primary, lower T brine–CH₄ assemblage. Laser ablation ICP-MS analyses show that the brine, hydrocarbon and halide melt inclusions contain significant concentrations of Cu (0.1–1 wt% range), Au, Bi, Ag and Pt (all 0.1–10 ppm range). Cu:Pt and Cu:Au ratios in the inclusions are significantly (up to 4 log units) lower than in the host alteration veins and adjacent massive sulfide ore veins, suggesting either (1) early Cu loss from the volatiles by chalcopyrite precipitation or (2) enhanced Au and Pt solubilities relative to Cu at the temperatures of entrapment. Concentration ratios between coexisting brine and CH₄ inclusions are lower for Cu, Au, Bi and Ag than for other elements (Na, Ca, Fe, Mn, Zn, Pb) indicating that during interaction with the brine, the hydrocarbon phase was enriched in ore metals. The high concentrations of ore metals in hydrocarbon, brine and halide melt phases confirm that both aqueous and non-aqueous volatiles were carriers of precious metals in the Sudbury environment over a wide range of temperatures. Volatile evolution and magmatic sulfide differentiation were clearly part of a single, continuous process in the Sudbury footwall. The exsolution of H₂O-poor volatiles from fractionated sulfide liquid may have been a principal mechanism controlling the final distribution of PGE and Au in the footwall ore systems. The study reports the first measurements of precious metal concentrations in fluid inclusions from a magmatic Ni–Cu–PGE environment (the Sudbury district). Electronic Supplementary Material Supplementary material is available for this article at     

An autochthonous geological model for the eastern Andes of Ecuador

We describe a traverse across the Cordillera Real and sub-Andean Zone of Ecuador, poorly known areas with very little detailed mapping and very little age control. The spine of the Cordillera comprises deeply eroded Triassic and Jurassic plutons, the roots of a major arc, emplaced into probable Palaeozoic pelites and metamorphosed volcanic rocks. The W flank comprises a Jurassic (?) submarine basaltic–andesitic volcanic sequence, which grades up into mixed Jurassic/Cretaceous volcanic and sedimentary rocks of the Inter-Andean Valley. The sub-Andean Zone, on the E flank of the Cordillera, comprises a newly recognized Cretaceous basin of cleaved mudrocks, quartz arenites and limestones. East of the syndepositional Cosanga Fault, the Cretaceous basin thins into a condensed sequence that is indistinguishable from the rocks of the adjacent hydrocarbon-bearing Oriente Basin. The principal penetrative deformation of the Cordillera Real was probably latest Cretaceous/Palaeocene. It telescoped the magmatic belts, but shortening was largely partitioned into the pelites between plutons. The plutons suffered inhomogenous deformation; some portions completely escaped tectonism. The pelites conserve two foliations. The earliest comprises slaty cleavage formed under low- or sub-greenschist conditions. The later is a strong schistosity defined by new mica growth. It largely transposed and obliterated the first. Both foliations may have developed during a single progressive deformation. We find inappropriate recent terrane models for the Cordillera Real and sub-Andean Zone of Ecuador. Instead we find remarkable similarities from one side of the Cordillera to the other, including a common structural history. In place of sutures, we find mostly intrusive contacts between major plutons and pelites. Triassic to Cretaceous events occurred on the autochthonous western edge of the Archaean Guyana Shield. The latest Cretaceous–Paleocene deformation is interpreted as the progressive collision of an oceanic terrane(s) with the South American continent. Young fault movements have subsequently juxtaposed different structural levels through the Cordillera Real orogen.     

广西金牙金矿有机包裹体激光拉曼光谱研究

金牙金矿是桂西北微细粒浸染型金矿床具有代表意义的典型矿床。其赋矿层位为三叠系中统百蓬组的富有机碳的浊积岩系。通过对成矿过程中有机包裹体的激光拉曼分子微探针研究认为:(1)有机质在成矿过程中会发生热降解,其降解产物烃的量可衡量热的程度;(2)无机组分和CO2/CH4 参数可用于研究热液的地球化学环境。     

多环芳烃在赤潮微藻光合作用中所起作用的研究

采用实验生态学的方法,研究了3种多环芳烃-菲、芘和蒽对3种赤潮微藻-赤潮异弯藻、亚历山大藻和中肋骨条藻光合速率的影响。结果表明:较低浓度的菲、芘和蒽处理使3种赤潮微藻的光合速率有所提高,而较高浓度处理则降低了藻细胞的光合速率。3种多环芳烃-菲、芘和蒽胁迫对赤潮异弯藻光合速率的96h·EC50分别为0.089、0.110和0.124mg·L-1,对中肋骨条藻的96h半抑制剂量分别为0.103、0.127和0.138mg·L-1,对亚历山大藻的96h半抑制剂量分别为0.116、0.131和0.141mg·L-1,说明3种多环芳烃对赤潮微藻均表现出一定的毒性效应,其中菲的毒性作用最强。UV-B辐射(0.3J·m-2的辐射剂量)和多环芳烃的联合作用一方面增强了菲、芘和蒽对3种赤潮微藻光合效率的抑制作用,导致光合速率明显降低,另一方面在一定程度上改变了3种多环芳烃毒性作用的强弱,使芘的毒性作用变得最强。     

Reactions of PAH with Chlorine and Chlorine Dioxide in Coal Tar Lined Pipes

In presence of disinfectants, PAH are remobilized from the coal tar lining of water distribution mains. Reactions of the PAH with chlorine and chlorine dioxide can lead to chlorinated PAH that might show higher mutagenic effects than the parent PAH. The application of the solid-phase microextraction as a sampling preparation method in combination with a gas chromatographic mass spectrometric device is a reliable and useful method to achieve detection limits in the lower nanogramme-per-liter level for PAH and chlorinated PAH. Thus, the reactions of four PAH (anthracene, fluoranthene, fluorene, and phenanthrene) with chlorine and chlorine dioxide under conditions prevalent in drinking water distribution systems could be investigated. In batch experiments with demineralized and drinking water at pH 7, the concentrations of fluoranthene, fluorene, and phenanthrene remained constant, whereas anthracene reacted quantitatively with both disinfectants. In these reactions, no chlorinated products could be detected, only mono-hydroxyanthracene and anthraquinone were formed. A reaction mechanism for both reaction products is proposed. The results suggest that oxidation is the major pathway of the reaction of PAH with disinfectants in the systems under investigation.     

A new seismic attribute for ambiguity reduction in hydrocarbon prediction

Hydrocarbon prediction from seismic amplitude and amplitude‐versus‐offset is a daunting task. Amplitude interpretation is ambiguous due to the effects of lithology and pore fluid. In this paper, we propose a new attribute “J” based on a Gassmann–Biot fluid substitution to reduce ambiguity. Constrained by seismic and rock physics, the J attribute has good ability to detect hydrocarbons from seismic data. There are currently many attributes for hydrocarbon prediction. Among the existing attributes, far‐minus‐near times far and fluid factor are commonly used. In this paper, the effectiveness of these two existing attributes was compared with the new attribute. Numerical modelling was used to test the new attribute “J” and to compare “J” with the two existing attributes. The results showed that the J attribute can predict the existence of hydrocarbon in different porosity scenarios with less ambiguity than the other two attributes. Tests conducted with real seismic data demonstrated the effectiveness of the J attribute. The J attribute has performed well in scenarios in which the other two attributes gave inaccurate predictions. The proposed attribute “J” is fast and simple, and it could be used as a first step in hydrocarbon analysis for exploration.     

液液萃取-超高效液相色谱法测定水中16种多环芳烃

多环芳烃(PAHs)因其难降解性、潜在毒性及环境中存在的广泛性,近年来受到越来越多的关注。本文通过色谱条件及检测波长的优化,建立了液液萃取-紫外荧光检测器串联超高效液相色谱法同时测定地下水中16 种 PAHs的分析方法。选用Waters PAH C18色谱柱,以水和乙腈作为流动相,通过调整流动相比例,实现了在16.5 min 内完成16种目标化合物的基线分离与检测,效率比传统高效液相色谱分析提高了一倍。该方法在0.01-5.00 mg/L之间具有良好的线性关系 (R2＞0.9999),PAHs 各化合物的方法检出限在1.25-7.02 ng/L之间,测定结果相对标准偏差(n=6)为0.80%-7.98%,加标回收率在65.0%-104%。本方法分析效率高,适用于批量地下水中PAHs同时筛查分析。     

Abiogenic Fischer–Tropsch synthesis of hydrocarbons in alkaline igneous rocks; fluid inclusion, textural and isotopic evidence from the Lovozero complex, N.W. Russia

A detailed fluid inclusion study has been carried out on the hydrocarbon-bearing fluids found in the peralkaline complex, Lovozero. Petrographic, microthermometric, laser Raman and bulk gas data are presented and discussed in context with previously published data from Lovozero and similar hydrocarbon-bearing alkaline complexes in order to further understand the processes which have generated these hydrocarbons. CH₄-dominated inclusions have been identified in all Lovozero samples. They occur predominantly as secondary inclusions trapped along cleavage planes and healed fractures together with rare H₂O-dominant inclusions. They are consistently observed in close association with either arfvedsonite crystals, partially replaced by aegirine, aegirine crystals or areas of zeolitization. The majority of inclusions consist of a low-density fluid with CH₄ homogenisation temperatures between −25 and −120 °C. Those in near-surface hand specimens contain CH₄+H₂ (up to 40 mol%)±higher hydrocarbons. However, inclusions in borehole samples contain CH₄+higher hydrocarbons±H₂ indicating that, at depth, higher hydrocarbons are more likely to form. Estimated entrapment temperatures and pressures for these inclusions are 350 °C and 0.2–0.7 kbar. A population of high-density, liquid, CH₄-dominant inclusions have also been recorded, mainly in the borehole samples, homogenising between −78 and −99 °C. These consist of pure CH₄, trapped between 1.2 and 2.1 kbar and may represent an early CH₄-bearing fluid overprinted by the low-density population. The microthermometric and laser Raman data are in agreement with bulk gas data, which have recorded significant concentrations of H₂ and higher hydrocarbons up to C₆H₁₂ in these samples. These data, combined with published isotopic data for the gases CH₄, C₂H₆, H₂, He and Ar indicate that these hydrocarbons have an abiogenic, crustal origin and were generated during postmagmatic, low temperature, alteration reactions of the mineral assemblage. This would suggest that these data favour a model for formation of hydrocarbons through Fischer–Tropsch type reactions involving an early CO₂-rich fluid and H₂ derived from alteration reactions. This is in contrast to the late-magmatic model suggested for the formation of hydrocarbons in the similar peralkaline intrusion, Ilímaussaq, at temperatures between 400 and 500 °C.     

PCB exposure in sea otters and harlequin ducks in relation to history of contamination by the Exxon Valdez oil spill

Exposure to contaminants other than petroleum hydrocarbons could confound interpretation of Exxon Valdez oil spill effects on biota at Prince William Sound, Alaska. Hence, we investigated polychlorinated biphenyls (PCBs) in blood of sea otters and harlequin ducks sampled during 1998. PCB concentrations characterized by lower chlorinated congeners were highest in sea otters from the unoiled area, whereas concentrations were similar among harlequin ducks from the oiled and unoiled area. Blood enzymes often elevated by xenobiotics were not related to PCB concentrations in sea otters. Only sea otters from the unoiled area had estimated risk from PCBs, and PCB composition or concentrations did not correspond to reported lower measures of population performance in sea otters or harlequin ducks from the oiled area. PCBs probably did not influence limited sea otter or harlequin duck recovery in the oiled area a decade after the spill.