Thermal doming-extension metallogenic system of Jiaodong type gold depositsSCIEI北大核心CSCD

胶东型金矿具有独特的成矿特征和成因机制,不同于国际已知金矿类型。为了深化认识控制矿床形成、变化和保存的地质要素及成矿过程,本文综合分析了胶东半岛晚中生代岩浆作用、构造活动和成矿特征及其构造背景,提出该区深部岩浆活动与地壳快速隆升及浅部变质核杂岩、张性断层、断陷盆地等伸展构造,共同控制了以Au为主的矿床成矿系列及成矿演化过程,谓之热隆-伸展成矿系统。阐明了晚中生代岩浆演化过程中的元素变化规律,发现了金矿化蚀变带中的低Ba、Sr含量异常及早白垩世胶东地壳中金丰度的显著变化,揭示了壳幔物质混合和伟德山型花岗岩岩浆活动对金成矿的贡献。认为这一成矿系统形成于古太平洋板块俯冲后撤的后俯冲伸展环境,由于软流圈上涌导致岩石圈地幔性质由富集向亏损转化,从而引起岩浆岩地球化学特征变化,地球化学元素重新调整,幔源含金流体与由重熔下地壳析出的壳源含金流体混合形成富金流体库,并产生贫金花岗岩。大规模岩浆活动为成矿元素的活化、迁移提供了热动力条件,上地壳伸展产生的断裂构造则为成矿元素聚集提供了良好空间。热隆-伸展成矿系统是中国东部晚中生代重要的成矿系统。     

Transformation of ammonium nitrogen and response characteristics of nitrifying functional genes in tannery sludge contaminated soil

High concentrations of ammonium nitrogen released from tannery sludge during storage in open air may cause nitrogen pollution to soil and groundwater. To study the transformation mechanism of NH₄⁺-N by nitrifying functional bacteria in tannery sludge contaminated soils, a series of contaminated soil culture experiments were conducted in this study. The contents of ammonium nitrogen (as NH₄⁺-N), nitrite nitrogen (as NO₂^?-N) and nitrate nitrogen (as NO₃^?-N) were analyzed during the culture period under different conditions of pollution load, soil particle and redox environment. Sigmodial equation was used to interpret the change of NO₃^?-N with time in contaminated soils. The abundance variations of nitrifying functional genes (amoA and nxrA) were also detected using the real-time quantitative fluorescence PCR method. The results show that the nitrification of NH₄⁺-N was aggravated in the contaminated silt soil and fine sand under the condition of lower pollution load, finer particle size and more oxidizing environment. The sigmodial equation well fitted the dynamic accumulation curve of the NO₃^?-N content in the tannery sludge contaminated soils. The Cr(III) content increased with increasing pollution load, which inhibited the reproduction and activity of nitrifying bacteria in the soils, especially in coarse-grained soil. The accumulation of NO₂^?-N contents became more obvious with the increase of pollution load in the fine sand, and only 41.5% of the NH₄⁺-N was transformed to NO₃^?-N. The redox environment was the main factor affecting nitrification process in the soil. Compared to the aerobic soil environment, the transformation of NH₄⁺-N was significantly inhibited under anaerobic incubation condition, and the NO₃^?-N contents decreased by 37.2%, 61.9% and 91.9% under low, medium and high pollution loads, respectively. Nitrification was stronger in the silt soil since its copy number of amoA and nxrA genes was two times larger than that of fine sand. Moreover, the copy numbers of amoA and nxrA genes in the silt soil under the aerobic environment were 2.7 times and 2.2 times larger than those in the anaerobic environment. The abundance changes of the amoA and nxrA functional genes have a positive correlation with the nitrification intensity in the tannery sludge-contaminated soil.     

The Paleoceanography during the Time with High δ13C of Phanerozoic marine carbonates

Carbon isotopic composition of marine carbonates is a record for various important geological events in the process of earth development and evolution. The carbonates of Carboniferous, Permian and Triassic, as the transition from Paleozoic to Mesozoic-Cenozoic have very high ¹³C value. Taking this as the main point, and combined with the oxygen, strontium isotopic composition in carbonates, distribution of carbonate basin area through geologic time, the correlation of carbon isotopic composition of marine carbonates to sea level change, organic carbon burial flux, exchange of CO₂ content in atmosphere and ocean, and long cycle evolution of the earth ecosystems were approached. The results are shown as follows: ①The interval of ¹³C >3‰ during Phanerozoic was concentrated in Carboniferous, Permian and the beginning of Triassic, but the beginning of Triassic was characterized by higher frequency and larger fluctuations in ¹³C value during a short time, whereas the Carboniferous-Permian presented a continuously stable high ¹³C value, indicating a larger amount of organic carbon accumulation in this time interval. Relatively high ¹⁸O values during this time was also observed, showing a long time of glaciations and cold climate, which suggest a connection among rapid organic carbon burial, cold climate, as well as pCO₂ and pO₂ states of atmosphere. ②The over consumption of atmosphere CO₂ by green plants during the time with high ¹³C of seawater forced CO₂ being transferred from ocean to atmosphere for the balance, but the decrease in the seawater amount and water column pressure caused by the global cooling could weaken dissolution capacity of CO₂ in seawater and carbon storage of marine carbonates, and also reduce the carbonate sedimentary rate and decrease the carbonate basin area globally from Devonian to Carboniferous and Permian. During the middle-late Permian carbonate was widely replaced by siliceous sediments even though in shallow carbonate platform, which resulted in the decrease of marine invertebrates, suggesting the Permian chert event should be global. ③The Phanerozoic ⁸⁷Sr/⁸⁶Sr trend of seawater showed a sharp fall in Permian and drop to a minimum at the end of the Permian, indicting input of strontium from the submarine hydrothermal systems (mantle flux). Such process should accompany with a supplement of CO₂ from deep earth to atmosphere and ocean system, but the process associated with widespread volcanism and rises of earth’s surface temperature pricked up the mass extinction during the time of end Permian. ④Cold climate and increase of continental icecap volume, the amalgamation of northern Africa and Laurentia continentals were the main reasons responsible for the sea level drop, but the water consumption result from the significantly increased accumulation of organic carbon should also be one of the reasons for the sea level drop on the order of tens of meters. ⑤The mass extinction at the end Permian was an inevitable event in the process of earth system adjustment. It was difficult for marine invertebrates to survive because of the continuously rapid burial of organic carbon, and of the decrease of sea water amount and its dissolution ability to CO₂. At last, at the end of Paleozoic, the supplement of CO₂ to atmosphere and ocean by widely magma activities resulted in a high temperature of earth surface and intensified mass extinction.     

Prediction of soil properties using imaging spectroscopy: Considering fractional vegetation cover to improve accuracy

Spectroscopic techniques have become attractive to assess soil properties because they are fast, require little labor and may reduce the amount of laboratory waste produced when compared to conventional methods. Imaging spectroscopy (IS) can have further advantages compared to laboratory or field proximal spectroscopic approaches such as providing spatially continuous information with a high density. However, the accuracy of IS derived predictions decreases when the spectral mixture of soil with other targets occurs. This paper evaluates the use of spectral data obtained by an airborne hyperspectral sensor (ProSpecTIR-VS – Aisa dual sensor) for prediction of physical and chemical properties of Brazilian highly weathered soils (i.e., Oxisols). A methodology to assess the soil spectral mixture is adapted and a progressive spectral dataset selection procedure, based on bare soil fractional cover, is proposed and tested. Satisfactory performances are obtained specially for the quantification of clay, sand and CEC using airborne sensor data (R² of 0.77, 0.79 and 0.54; RPD of 2.14, 2.22 and 1.50, respectively), after spectral data selection is performed; although results obtained for laboratory data are more accurate (R² of 0.92, 0.85 and 0.75; RPD of 3.52, 2.62 and 2.04, for clay, sand and CEC, respectively). Most importantly, predictions based on airborne-derived spectra for which the bare soil fractional cover is not taken into account show considerable lower accuracy, for example for clay, sand and CEC (RPD of 1.52, 1.64 and 1.16, respectively). Therefore, hyperspectral remotely sensed data can be used to predict topsoil properties of highly weathered soils, although spectral mixture of bare soil with vegetation must be considered in order to achieve an improved prediction accuracy.     

Non-destructive estimation of foliar chlorophyll and carotenoid contents: Focus on informative spectral bands

Leaf pigment content provides valuable insight into the productivity, physiological and phenological status of vegetation. Measurement of spectral reflectance offers a fast, nondestructive method for pigment estimation. A number of methods were used previously for estimation of leaf pigment content, however, spectral bands employed varied widely among the models and data used. Our objective was to find informative spectral bands in three types of models, vegetation indices (VI), neural network (NN) and partial least squares (PLS) regression, for estimating leaf chlorophyll (Chl) and carotenoids (Car) contents of three unrelated tree species and to assess the accuracy of the models using a minimal number of bands. The bands selected by PLS, NN and VIs were in close agreement and did not depend on the data used. The results of the uninformative variable elimination PLS approach, where the reliability parameter was used as an indicator of the information contained in the spectral bands, confirmed the bands selected by the VIs, NN, and PLS models. All three types of models were able to accurately estimate Chl content with coefficient of variation below 12% for all three species with VI showing the best performance. NN and PLS using reflectance in four spectral bands were able to estimate accurately Car content with coefficient of variation below 14%. The quantitative framework presented here offers a new way of estimating foliar pigment content not requiring model re-parameterization for different species. The approach was tested using the spectral bands of the future Sentinel-2 satellite and the results of these simulations showed that accurate pigment estimation from satellite would be possible.     

基于CALIPSO卫星资料的京津冀地区MODIS卷云云顶高度订正

卷云在大气辐射中扮演着重要角色,对天气系统和气候变化产生重要影响。相比传统地基观测手段,卫星遥感更容易探测到高层卷云的信息,本文利用CALIOP主动遥感仪器可获取较为准确的薄卷云特性的特点,针对MODIS被动遥感探测器反演的薄卷云云顶高度的偏差开展订正研究。研究选取2013～2017年京津冀地区MODIS云产品,结合CALIPSO卫星的卷云云顶高度数据,基于交叉验证的方法得到线性拟合方案,对MODIS卷云云顶高度进行订正。订正后的MODIS与CALIPSO卷云云顶高度差值的分布区间由?3～2 km变为?2.0～2.5 km,峰值由?0.8 km左右变为0.2 km左右。订正效果随云顶高度和云光学厚度的不同有所变化,其中较低层卷云和光学薄卷云的订正效果更明显。     

Doppler Images of ζ Andromedae

Doppler images are presented for the RS CVn-type binary ζ And. Our upgraded Doppler imaging code TempMap_ε takes into account the distorted geometry of the primary giant component. On the maps several low latitude spots are restored with a temperature contrast of about 1000 K. Some weak polar features are also found. Cross-correlation of the consecutive Doppler-maps suggests solar-like differential surface rotation.     

卫星数字图象处理与制图分析——以京津及邻区1:25万影象图的处理分析为例

利用计算机进行图象处理和彩色制印,编制了京津及邻区1:25万影象图。采用经数字处理的图象和制图分析等编改工艺,取得了高质量低成本的效果。     

UBV光电测光系统的转换方程和精度比较

根据对鬼星团中Ｊｏｈｎｓｏｎ测光标准星的观测，我们研究了北京天文台６０ｃｍ望远镜直流光电光度计ＵＢＶ测光系统的转换方程．应用该方程推算了对三颗变星观测得到的ＵＢＶ星等，讨论了所得光变曲线的精度，并与较差方法所得结果进行了比较     

Imaging Borrelly

The nucleus, coma, and dust jets of short-period Comet 19P/Borrelly were imaged from the Deep Space 1 spacecraft during its close flyby in September 2001. A prominent jet dominated the near-nucleus coma and emanated roughly normal to the long axis of nucleus from a broad central cavity. We show it to have remained fixed in position for more than 34 hr, much longer than the 26-hr rotation period. This confirms earlier suggestions that it is co-aligned with the rotation axis. From a combination of fitting the nucleus light curve from approach images and the nucleus' orientation from stereo images at encounter, we conclude that the sense of rotation is right-handed around the main jet vector. The inferred rotation pole is approximately perpendicular to the long axis of the nucleus, consistent with a simple rotational state. Lacking an existing IAU comet-specific convention but applying a convention provisionally adopted for asteroids, we label this the north pole. This places the sub-solar latitude at ∼60° N at the time of the perihelion with the north pole in constant sunlight and thus receiving maximum average insolation.