Enceladus' water vapor plume

The Cassini spacecraft flew close to Saturn's small moon Enceladus three times in 2005. Cassini's UltraViolet Imaging Spectrograph observed stellar occultations on two flybys and confirmed the existence, composition, and regionally confined nature of a water vapor plume in the south polar region of Enceladus. This plume provides an adequate amount of water to resupply losses from Saturn's E ring and to be the dominant source of the neutral OH and atomic oxygen that fill the Saturnian system.     

Diviner Lunar Radiometer observations of the LCROSS impact

The Lunar Reconnaissance Orbiter (LRO) Diviner instrument detected a thermal emission signature 90 seconds after the Lunar Crater Observation and Sensing Satellite (LCROSS) Centaur impact and on two subsequent orbits. The impact heated a region of 30 to 200 square meters to at least 950 kelvin, providing a sustained heat source for the sublimation of up to ~300 kilograms of water ice during the 4 minutes of LCROSS post-impact observations. Diviner visible observations constrain the mass of the sunlit ejecta column to be ~10(-6) to 10(-5) kilograms per square meter, which is consistent with LCROSS estimates used to derive the relative abundance of the ice within the regolith.     

Spitzer spectral observations of the deep impact ejecta

Spitzer Space Telescope imaging spectrometer observations of comet 9P/Tempel 1 during the Deep Impact encounter returned detailed, highly structured, 5- to 35-micrometer spectra of the ejecta. Emission signatures due to amorphous and crystalline silicates, amorphous carbon, carbonates, phyllosilicates, polycyclic aromatic hydrocarbons, water gas and ice, and sulfides were found. Good agreement is seen between the ejecta spectra and the material emitted from comet C/1995 O1 (Hale-Bopp) and the circumstellar material around the young stellar object HD100546. The atomic abundance of the observed material is consistent with solar and C1 chondritic abundances, and the dust-to-gas ratio was determined to be greater than or equal to 1.3. The presence of the observed mix of materials requires efficient methods of annealing amorphous silicates and mixing of high- and low-temperature phases over large distances in the early protosolar nebula.     

十字花科根肿病菌在水中存活能力检测分析

为了研究根肿菌休眠孢子的萌发及侵染环境温度之间的互作关系,利用荧光定量PCR法,对16～25℃区间各实验处理水体中根肿病休眠孢子浓度进行检测,分析不同温度条件对水体中根肿菌的影响,同时通过检测水体中的化学需氧量、溶氧量、电导率判断水体中根肿菌的存活能力。结果表明,16～25℃区间内随着温度的提高根肿菌孢子下降速率变缓,在25℃时最为缓慢,在30 d达1.88×10~6 CFU/mL,并在60 d后相对稳定。水体中化学需氧量、溶氧量、电导率的检测结果表明,在28 d水中根肿菌的活动十分剧烈,35 d时化学需氧量、溶氧量、电导率值分别高达86.2、5.95 mg/L、10~3μS/cm,且与其他温度存在显著差异。说明根肿菌的存活能力在25℃相对于其他温度更强。     

Fine particles in the soufriere eruption plume

The size distributions of fine particles measured at tropospheric altitudes in the periphery of the eruption plume formed during the 17 April 1979 eruption of Soufriere Volcano and in the low-level effluents on 15 May 1979 were found to be bimodal, having peak concentrations at geometric mean diameters of 1.1 and 0.23 micrometers. Scanning electron microscopy and energy-dispersive x-ray analysis of the samples revealed an abundance of aluminum and silicon and traces of sodium, magnesium, chlorine, potassium, calcium, and iron in the large-particle mode. The submicrometer-sized particles were covered with liquid containing sulfur, assumed to be in the form of liquid sulfuric acid.     

碱渣在广东酸性土壤上的农用化开发前景

着重阐述碱渣对环境的影响,综合分析碱渣的国内外应用概况,结合南方土壤尤其是广东酸性土壤的特点以及近年碱渣在广东主要作物上的初步施用效果,提出碱渣的农用化综合开发途径和乐观的市场前景。     

A late Triassic impact ejecta layer in southwestern Britain

Despite the 160 or so known terrestrial impact craters of Phanerozoic age, equivalent ejecta deposits within distal sedimentary successions are rare. We report a Triassic deposit in southwestern Britain that contains spherules and shocked quartz, characteristic of an impact ejecta layer. Inter- and intragranular potassium feldspar from the deposit yields an argon-argon age of 214 +/- 2.5 million years old. This is within the age range of several known Triassic impact craters, the two closest of which, both in age and location, are Manicouagan in northeastern Canada and Rochechouart in central France. The ejecta deposit provides an important sedimentary record of an extraterrestrial impact in the Mesozoic that will help to decipher the number and effect of impact events, the source and dynamics of the event that left this distinctive sedimentary marker, and the relation of this ejecta layer to the timing of extinctions in the fossil record.     

Detection of the water reservoir in a forming planetary system

Icy bodies may have delivered the oceans to the early Earth, yet little is known about water in the ice-dominated regions of extrasolar planet-forming disks. The Heterodyne Instrument for the Far-Infrared on board the Herschel Space Observatory has detected emission lines from both spin isomers of cold water vapor from the disk around the young star TW Hydrae. This water vapor likely originates from ice-coated solids near the disk surface, hinting at a water ice reservoir equivalent to several thousand Earth oceans in mass. The water's ortho-to-para ratio falls well below that of solar system comets, suggesting that comets contain heterogeneous ice mixtures collected across the entire solar nebula during the early stages of planetary birth.     

Nitrogen oxide reactions in the urban plume of Boston

The rate of removal or conversion of nitrogen oxides has been determined from airborne measurements in the urban plume of Boston. The average pseudo-first-order rate constant for removal was 0.18 per hour, with a range of 0.14 to 0.24 per hour under daylight conditions for four study days. The removal process is dominated by chemical conversion to nitric acid and organic nitrates. The removal rate suggests an atmospheric lifetime for nitrogen oxides of about 5 to 6 hours in urban air.     

Impact ejecta layer from the mid-Devonian: possible connection to global mass extinctions

We have found evidence for a bolide impacting Earth in the mid-Devonian ( approximately 380 million years ago), including high concentrations of shocked quartz, Ni, Cr, As, V, and Co anomalies; a large negative carbon isotope shift (-9 per mil); and microspherules and microcrysts at Jebel Mech Irdane in the Anti Atlas desert near Rissani, Morocco. This impact is important because it is coincident with a major global extinction event (Kacák/otomari event), suggesting a possible cause-and-effect relation between the impact and the extinction. The result may represent the extinction of as many as 40% of all living marine animal genera.     

Mantle plume helium in submarine basalts from the galapagos platform

Helium-3/helium-4 ratios in submarine basalt glasses from the Galapagos Archipelago range up to 23 times the atmospheric ratio in the west and southwest. These results indicate the presence of a relatively undegassed mantle plume at the Galápagos hot spot and place Galápagos alongside Hawaii, Iceland, and Samoa as the only localities known to have such high helium-3/helium-4 ratios. Lower ratios across the rest of the Galápagos Archipelago reflect systematic variations in the degree of dilution of the plume by entrainment of depleted material from the asthenosphere. These spatial variations reveal the dynamics of the underlying mantle plume and its interaction with the nearby Galápagos Spreading Center.     

基于高光谱的油茶籽含水量检测方法

为了快速精准检测油茶籽含水量,解决传统烘干检测法费时费力等问题,提出一种基于高光谱技术的油茶籽含水量无损检测方法。以油茶籽为研究对象,测定油茶籽含水量,建立光谱模型,对油茶籽光谱分别进行Savitzky-Golay(S-G)卷积平滑、一阶微分、二阶微分和多元散射校正(MSC)预处理,通过逐步回归提取有效敏感波长,并采用偏最小二乘回归(PLSR)、BP神经网络和径向基(RBF)神经网络方法分别建立预测模型,对模型进行外部验证,选出最优预测模型。研究表明:相关系数较高的光谱敏感波段为410~450、600~620、780~880、940~971 nm。基于MSC预处理光谱建立的PLSR模型,在校正集上的相关系数为0.953 4、均方根误差为0.22%,在验证集上的相关系数为0.939 9、均方根误差为0.27%,优于BP神经网络模型和RBF神经网络模型。结果说明,采用高光谱技术检测油茶籽含水量是可行的,研究内容可为油茶籽含水量的在线无损检测提供有效依据。     

Trajectories of the mount st. Helens eruption plume

The plume of the major eruption of Mount St. Helens on 18 May 1980 penetrated 10 to 11 kilometers into the stratosphere, attaining heights of 22 to 23 kilometers. Wind shears rapidly converted the plume from an expanding vertical cone to a thin, slightly inclined lamina. The lamina was extruded zonally in the stratosphere as the lower part moved eastward at jet stream velocities, while the upper part slowly moved westward in the region of nonsteady transition from the westerlies to the summer stratospheric easterlies. Trajectories computed to position the NASA U-2 aircraft for sampling in the plume are described. Plume volume after 8 hours of strong volcanic emission is estimated at 2 x 10(6) cubic kilometers. Only about 1 percent of this volume is attributed to the volcano; the rest was entrained from the environment.     

Gaseous constituents in the plume from eruptions of mount st. Helens

Measurements in the stratosphere of gaseous constituents in the plume of Mount St. Helens were obtained during five flights of the NASA U-2 aircraft between 19 May and 17 June 1980. Mixing ratios from gas chromatographic measurements on samples acquired about 24 hours after the initial eruption show considerable enhancement over nonvolcanic concentrations for sulfur dioxide (more than 1000 times), methyl chloride (about 10 times), and carbon disulfide (more than 3 times). The mixing ratio of carbonyl sulfide was comparable to nonvolcanic mixing ratios although 3 days later it was enhanced two to three times. Ion chromatography measurements on water-soluble constituents are also reported. Very large concentrations of chloride, nitrate, and sulfate ions were measured, implying large mixing ratios for the water-soluble gaseous constituents from which the anions are derived. Measurements of radon-222 present in the plume are also reported.     

Discovery of gaseous S2 in Io's Pele plume

Spectroscopy of Io's Pele plume against Jupiter by the Hubble Space Telescope in October 1999 revealed absorption due to S2 gas, with a column density of 1.0 +/- 0.2 x 10(16) per square centimeter, and probably also SO(2) gas with a column density of 7 +/- 3 x 10(16) per square centimeter. This SO2/S2 ratio (3 to 12) is expected from equilibration with silicate magmas near the quartz-fayalite-magnetite or wüstite-magnetite buffers. Condensed S3 and S4, probable coloring agents in Pele's red plume deposits, may form by polymerization of the S2, which is unstable to ultraviolet photolysis. Diffuse red deposits near other Io volcanoes suggest that venting and polymerization of S2 gas is a widespread feature of Io volcanism.     

基于国际公约要求的压载水生物检测技术

《国际船舶压载水和沉积物控制与管理公约》D-2排放标准对排放压载水中10~50μm生物、大于等于50μm生物、大肠埃希氏菌、肠道球菌和霍乱弧菌的活体数量提出了具体的要求。目前各国已重视并针对压载水处理做了大量研究,但如何对压载水中活体生物开展有效检测,尤其是快速检测尚存在问题。介绍了目前国际上使用的几种主要检测方法,如显微镜观察法、流式细胞技术、微流控芯片技术、分子生物学技术、MPN法、平板法等,以及几种方法的原理、使用特点和在压载水快速检测中的限制性。基于快速、准确、样品消耗量小、自动程度高的特点,流式细胞术法是目前最适合发展用于港口压载水生物快速检测的方法。公约未对排放压载水中孢囊的数量有详细规定,相应的研究也很少,但孢囊对压载水排放地生态系统潜在破坏性更大,因此建议加强对孢囊方面的研究。     

部分新疆杏品种水不溶性固形物含量的测定

水不溶性固形物含量是杏干制备的一项重要指标。以14个华北杏为对照,研究了33个新疆杏品种的水不溶性固形物含量。结果表明,两大品种群的杏水不溶性固形物含量在总体上差异不明显,水不溶性固形物含量在品种间有明显差异。在新疆杏中,赛来克佳娜丽、卡巴克胡安娜、托户地库都、卡巴克西米西的水不溶性固形物含量均高于是2.5%,是比较理想的制干品种。不同成熟期的杏水不溶性固形物含量存在显著差异,研究表明从中熟品种群中选择高水不溶性固形物含量的品种最为有效。另外,采摘期也明显影响水不溶性固形物含量,制备杏干宜在八成熟时采摘。     

Aerosols from the soufriere eruption plume of 17 april 1979

Aerosol samples collected from the 17 April 1979 eruption plume of Soufriere, St. Vincent, at altitudes between 1.8 and 5.5 kilometers were physically and chemically very similar to the ash that fell on the island. Higher altitude samples (7.3 and 9.5 kilometers) had a much lower ash content but comparable concentrations of sulfate, which were above the background concentration found at these altitudes.     

基于激光诱导击穿光谱的地下水中Fe和Mn的检测

采用激光诱导击穿光谱(LIBS)技术并结合在锌基板上液固转换的样品处理方法,对标准水溶液样品中Fe、Mn进行检测,并根据标准曲线法建立Fe、Mn的定量模型;再利用所建立的LIBS定量模型,对洞庭湖区地下水实际水样中Fe、Mn含量进行检测,并与电感耦合等离子体质谱法(ICP–MS)的检测结果进行比较。结果表明：得到Fe、Mn的LIBS定标曲线的决定系数均大于0.98,相对标准偏差均为4.3%,留一交叉验证均方根误差分别为0.024、0.007 mg/L,Fe、Mn的检出限分别为0.028、0.008 mg/L;采用LIBS对洞庭湖地下水实际水样中Fe、Mn含量检测的结果与ICP–MS的检测结果基本一致,平均相对误差小于10%。     

The acraman impact structure: source of ejecta in late precambrian shales, South australia

A major probable impact structure occurs in middle Proterozoic dacitic volcanics in the Gawler Ranges, central South Australia. The structure has an inner depressed area about 30 kilometers in diameter that contains the Lake Acraman salina, an intermediate depression or ring about 90 kilometers in diameter, and a possible outer ring approximately 160 kilometers in diameter. Outcrops of dacite in Lake Acraman are intensely shattered and contain shatter cones and multiple sets of shock lamellac in quartz grains. The Acraman structure is the largest probable impact structure known in Australia and is the likely source of dacitic ejecta found in late Precambrian marine shales some 300 kilometers to the east.