The first detection of propane on Saturn

We report the first detection of propane, C₃H₈, in Saturn's stratosphere. Observations taken on September 8, 2002 UT at NASA's IRTF using TEXES, show multiple emission lines due to the 748 cm⁻¹ν₂₁ band of C₃H₈. Using a line-by-line radiative transfer code, we are able to fit the data by scaling the propane vertical mixing ratio profile from the photochemical model of Moses et al. [2000. Icarus 143, 244-298]. Multiplicative factors of 0.7 and 0.65 are required to fit the −20° and −80° planetocentric latitude spectra. The resultant profiles are characterized by a 5 mbar mixing ratio of 2.7±0.8×¹⁰⁻⁸ at −20° and at −80° latitude. These results suggest that the time scale for meridional circulation lies between the net photochemical lifetimes of C₂H₂ and C₃H₈, ≈30-600 years.     

东洞庭湿地植被格局变化及其影响因素

东洞庭湖(也称东洞庭)湿地植被格局的变化特征及其影响因素的分析是该地区湿地植被保护与恢复策略制定的基础。基于美国陆地资源卫星Landsat TM/ETM+数据,应用决策树分类法分别提取东洞庭湖1999年、2002年、2006年三个时期湿地景观信息,通过转移矩阵法和质心迁移法对植被的时空演变分析。结果表明:(1)1993～2002年东洞庭湖芦苇、林地、苔草滩地面积均有所增加,芦苇增长速度最快,年均增长面积为28.93km²;2002～2006年林地面积迅速增加,年均增长面积为29.655km²,苔草面积有所减少,芦苇面积保持基本稳定;(2)东洞庭湖湿地植被质心呈现从林地—芦苇—苔草逐层靠近湖心的分布特点,1993～2006年三种植被类型的质心均不断向湖心迁移,其中以林地与芦苇的变迁更为显著。     

Characterization of particulate matter in the Apulia Region (South of Italy): features and critical episodes

The chemical composition of PM₁₀ and PM_2.5 samples collected during two seasonal monitoring campaigns at residential, urban and industrial Apulia Region- sites was investigated. Ionic fraction, carbonaceous compounds and Polycyclic Aromatic Hydrocarbons were determined for all samples. High correlations among PM data collected in the investigated sites suggested the regional character of particulate matter. It was also confirmed by five days back trajectories analysis. Moreover, no significant seasonal trend in PM mass concentration was observed in the investigated sites. These results, relevant for the area under investigations, were not observed in the North of Italy and Europe and allow to conclude that PM₁₀ and PM_2.5 cannot be considered ‘good’ indicators for the evaluation of local anthropic contributions to air quality. On the contrary, the high levels of Polycyclic Aromatic Hydrocarbons found in Taranto sampling sites suggested that PAHs can be a better indicator for this purpose. This result is also relevant in order to weigh the importance of industrial area and to suggest right policy control to decision makers.     

Geochemistry and geochronology of HP mélanges from Tinos and Andros,cycladic blueschist belt,Greece

U–Pb zircon geochronology, Sr–Nd isotope and bulk-rock geochemistry have been applied to meta-igneous and meta-sedimentary rocks from high-pressure metamorphic mélanges exposed on the Cycladic islands of Tinos, Syros and Andros. Ion microprobe (SHRIMP) U–Pb zircon dating of 7 samples representing meta-igneous blocks (Tinos), a blackwall zone (Tinos) and chlorite–talc schists from block-matrix contacts (Syros and Tinos) yielded Cretaceous ages of c. 80 Ma. Many of the criteria commonly used to distinguish between magmatic or metamorphic zircon genesis (internal structure, Th/U ratio, REE characteristics, Ti-in zircon thermometry, enclosed mineral phases) do not provide unambiguous constraints for the mode of formation. However, a magmatic origin for Cretaceous zircon of meta-gabbros and eclogites is considered likely. Supporting evidence for a previously suggested metamorphic origin for c. 80 Ma zircon in eclogite has not been found. Zircon of the same age occurring in chlorite–talc schists is presumably related to non-magmatic processes. Well-defined Cretaceous age groups clustering at c. 79 Ma also occur in the detrital zircon populations of 2 quartz mica schists representing the mélange matrix on Tinos, and suggest a much later time for sediment accumulation than previously assumed. The importance of c. 57 Ma zircon ages remains unclear, but may record either HP metamorphic processes or a post-57 Ma depositional age. The youngest age group in a third quartz mica schist from Tinos, collected outside the main mélange occurrences, clusters at c. 226–238 Ma. In all clastic metasediments from Tinos, most data points plot along the concordia between c. 300 and 900 Ma; single data points indicate concordant ages of c. 2.5 Ga, 2.3 Ga and 1 Ga, respectively. The youngest ²⁰⁶Pb/²³⁸U age group that has been recognized in a felsic paragneiss from Andros indicates an age of 163.1 ± 3.9 Ma, and mostly represents overgrowths around zircon with ages in the range from ～ 272 to ～ 289 Ma. Single data points of other inherited cores provided ²⁰⁶Pb/²³⁸U ages of c. 630 and c. 930 Ma. Meta-gabbros from Tinos show a large compositional variability and were found at 4 locations, each with distinct compositional characteristics, suggesting different crystallization histories, different sources and/or significant post-magmatic disturbance. The geochemistry of mélange blocks and the identical U–Pb zircon ages suggest that the block-matrix associations on Tinos and Syros can be grouped together. On a broader regional scale, there seem to be similarities between some meta-igneous rocks from Tinos and Evvia. Field relationships indicate that the mélanges occurring in southern Andros and northern Tinos can be correlated, but supporting geochemical and/or geochronological evidence for this interpretation could not be established. Previously published Jurassic ages for mafic and felsic mélange blocks from Andros suggest a genetic relationship to the ophiolite occurrences exposed in the larger Balkan region. A similar regional correlation is also considered likely for the Cretaceous meta-gabbros from Tinos and Syros, but cannot be documented with certainty.     

Development of Kinetic Inductance Detectors for Cosmic Microwave Background experiments

We describe the design, optimization, electrical and optical tests of Microwave Kinetic Inductance Detectors (MKIDs) for the mm-wave range. Our detectors are based on a novel resonator design, and are suitable for ground-based astronomical observations in the 143 GHz atmospheric window. The measured optical Noise Equivalent Power (NEP) at 0.3 K is $\sim 10^{-16}~\text{W}/\sqrt{\rm Hz}$ under a 300 K background load. This is equivalent or better than the performance of the best current bolometric detectors for the 140 GHz atmospheric window, limited by atmospheric noise in the best available sites. We also describe which improvements can be introduced to reduce the NEP of our detector, for lower background applications (narrow band or space-based).     

Modelling soil heat flux

A mathematical model to calculate soil heat flux in three steps is presented. In the first, an hourly air temperature based on the average daily temperature, using Fourier series coefficients is estimated. The estimated hourly air temperature constitutes an input variable for the second step of the model. In the second step, heat transfer principles, using the thermal properties of the soil in order to obtain a soil temperature profile in a 1-m-depth soil stratum, is applied. Finally, the results of the second stage are used to numerically calculate hourly heat flux in the soil. Correlation coefficients between observed and calculated hourly temperature values over the three summer months were 0.98, 0.97 and 0.96. Correlation coefficient for the entire study period between observed and estimated soil heat-flux values was 0.92 with a mean square error of 19.8 W m^–2.     

Biostratigraphy and paleoenvironmental characterization of the Middle Ordovician from the Sierras Subandinas (NW Argentina) based on organic-walled microfossils and sequence stratigraphy

Middle Ordovician acritarchs, including enigmatic, spore-like microfossils, are recorded from the Labrado and Capillas formations, of the Sierras Subandinas (Capillas River Section, Sierra de Zapla), northwestern Argentina. The Sierras Subandinas represent the outermost exposures of the Central Andean Basin that display an alternation of shallow-marine deltaic systems and estuarine environments, where relative sea-level fluctuations are frequent. The scarcity of fossils in the section, due to the marginal marine settings and frequent subaerial exposures, hinders the biostratigraphic constraining of these sedimentary successions. Based on the palynological assemblages, a probably Dapingian age is interpreted for the upper Lagunilla Member of the Labrado Formation, whereas the lower part of the Capillas Formation is assigned to the Darriwilian. Acritarchs from the lower part of the Capillas Formation indicate clear affinities with the “peri-Gondwana province”. However the lack of Frankea, a marker taxa for the Middle Ordovician, could be related either to the intermediate paleolatitudinal position of the Central Andean Basin or to local paleoenvironmental conditions. The facies analysis and the distribution of palynomorph assemblages throughout the studied section, suggest that organic-walled microfossils are influenced by local paleoenvironmental conditions. A probable non-marine origin is proposed for the spore-like microfossils co-occurring within the acritarch assemblages.