Spectroscopic Characterization of Fulvic Acid Fractions of a Contaminated Groundwater     

M. U. Kumke  C. Zwiener  G. Abbt-Braun  F. H. Frimmel 《洁净——土壤、空气、水》1999,27(6):409-415

Two fulvic acid (FA) samples taken from a former gas production facility in the Southwest of Germany were characterized using advanced fluorescence techniques. Steady-state fluorescence (fluorescence excitation, synchronous fluorescence) as well as time-resolved fluorescence were applied. Distinct differences between the sample B22 FA taken within the contamination plume and the sample B53 FA taken downstream were found. Comparison with a model compound for metabolites and humic substances revealed that due to the downstream passage the characteristics of the dissolved organic matter became more humic-like. The assignment of single classes of compounds in the sample B22 FA is discussed in terms of their synchronous fluorescence spectra and fluorescence decay time distribution.  相似文献   

Saalian to Weichselian stratigraphy and sedimentation along the Lågjæren – Høgjæren escarpment,southwest Norway     

Knut Stalsberg  Jon Y. Landvik  Eiliv Larsen  Hans Petter Sejrup 《第四纪科学杂志》1999,14(4):299-312

Quaternary sediments along a profile crossing the southern part of the Jæren escarpment, southwestern Norway, have been investigated with regard to their glacial history and sea-level variations. Deposits from at least three glaciations and two ice-free periods between Oxygen Isotope Stage 6 and the Late Weichselian have been identified. Subglacial till directly overlain by a glaciomarine regressional succession indicates a deglaciation, and amino acid ratios in Elphidium excavatum between 0.083 and 0.118 date this event to Oxygen Isotope Stage 6. Sea-level dropped from 130 to below 110 m a.s.l. Subsequently, a short-lived ice advance deposited a marginal moraine and a sandur locally on the escarpment. Stratigraphical position and luminescence dates around 148 ka BP suggest deposition during the final stage 6 deglaciation. A Late Weichselian till covers most of the surface of Jæren. In addition to a well documented westerly ice flow, glaciotectonic indications of ice flow towards the north have been found. Ice flow directions and a hiatus between Oxygen Isotope Stage 6 and the Weichselian indicate enhanced erosion along the escarpment and the influence of a Norwegian Channel ice-stream. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Combined Effects of Molecular Size and Electroendosmotic Flow on the Capillary Electrophoretic Behaviour of Humic Substances     

M. De Nobili  G. Bragato  A. Mori 《洁净——土壤、空气、水》1998,26(3):186-190

The electroendosmotic flow (EOF), generated by the migration of solvated ions near the charged capillary surface, is an important factor in determining the capillary electrophoretic behaviour of humic substances (HS). We investigated the electrophoretic mobilities of HS fractions of reduced molecular-weight polydispersity extracted from peat and from a spodosol either in the presence or after suppression of the EOF. When the EOF was not suppressed, HS migrated to the cathode in spite of their negative charge. Fractionation of HS according to molecular size was achieved in polyacrylamide-coated capillaries filled with 0.05 M tris-phosphate buffer. In uncoated capillaries filled with the same buffer, all fractions had very close mobilities. Addition of polyethylene glycol MW 4000 at concentrations above its entanglement threshold caused the migration times of larger molecules to increase more than those of smaller molecules. The separation was a linear function of molecular size up to 75000 g mol^–1 for peat HS and to 50000 g mol^–1 for HS extracted from the spodosol.  相似文献   

正六边形规则格网表达的DEM谷地线提取     

王璐  艾廷华 《测绘学报》2019,48(6):780-790

基于规则格网DEM谷地线提取受格网的几何形态、空间剖分和网格布局影响较大.传统的四边形格网D8 算法中,四边形网格的角邻域与边邻域存在的距离度量差异,影响了其计算结果对于地形变化的表达在两方向上的均衡性,从而影响了谷地线提取结果.六边形格网具有邻域一致、各向同性、紧凑、采样率高等优点,在空间场建模中越来越得到重用.本文旨在探求六边形格网结构在DEM谷地线提取中的性能特征,发现其与四边形格网比较的突出优势.基于六邻域处理单元,对六边形格网DEM谷地线提取过程中填洼、流向计算及平地区域流向判定作预处理,然后对流向线作拓扑连通组织,从而实现基于六边形DEM的谷地线提取.本文比较发现六边形方法在谷地线形状特征保持方面能力强,随着分辨率减小,六边形DEM所提取的谷地线与实测数据吻合程度高,弯曲特征继承性强.同时,在相同数据存储量条件下,六边形DEM数据精度更高,且其提取的谷地线网络的形状特征更为精细.  相似文献   

UAV for mapping shrubland vegetation: Does fusion of spectral and vertical information derived from a single sensor increase the classification accuracy?     

《International Journal of Applied Earth Observation and Geoinformation》2019

High quality data on plant species occurrence count among the essential data sources for ecological research and conservation purposes. Ecologically valuable small grain mosaics of heterogeneous shrub and herbaceous formations however pose a challenging environment for creating such species occurrence maps. Remote sensing can be useful for such purposes, it however faces several challenges, especially the need of ultra high spatial resolution (centimeters) data and distinguishing between plant species or genera. Unmanned aerial vehicles (UAVs) are capable of producing data with sufficient resolution; their use for identification of plant species is however still largely unexplored. A fusion of spectral data with LiDAR-derived vertical information can improve the classification accuracy, such a solution is however costly. A cheaper alternative of vertical data acquisition can be represented by the use of the structure-from-motion photogrammetry (SfM) utilizing the images taken for (multi/hyper)spectral analysis. We investigated the use of such a fusion of UAV-borne multispectral and SfM-derived vertical information acquired from a single sensor for classification of shrubland vegetation at species level and compared its accuracy with that derived from multispectral information only. Multispectral images were acquired using Tetracam Micro-MCA6 camera in the west of Czechia in a shrubland landscape protected within the NATURA 2000 network. Using (i) multispectral imagery only and (ii) multispectral-SfM fusion, we classified the vegetation into six classes representing four woody plant species and two meadow types. Our results prove that the multispectral-SfM fusion performs significantly better than multispectral only (88.2% overall accuracy, 85.2% mean producer’s accuracy and 85.7% mean user’s accuracy for fusion instead of 73.3%, 75.1% and 63.7%, respectively, for multispectral). We concluded that the fusion of multispectral and SfM information acquired from a single UAV sensor is a viable method for shrub species mapping.  相似文献   

大气和地下水中SF6测试技术   总被引：3，自引：0，他引：3  

张俊刚  李晶晶  周爱国  刘存富 《地球学报》2005,26(Z1):293-295

SF6是一种无色、无嗅、无毒、不易燃的惰性气体，具有良好的绝缘性、灭弧性和散热性。由于SF6具有化学惰性、大气圈和水圈中本底浓度低、检测灵敏度高等优点，它成为一种较为理想的大气、水文示踪剂。另外，在年轻地下水测年领域，SF6法已经逐渐有取代其他测年工具（3H法、CFCs法、3H/3He法）的趋势，特别适合研究1970年以后补给水的年龄。本文基于气相色谱仪和电子捕获检测器，设计了一套SF6提取制样分析系统，发展了SF6测试技术。  相似文献   

Effects of light intensity on Opsin4, Opsin5, and Pax6 expressions of the sea urchin Strongylocentrotus intermedius     

Mingfang Yang  Yushi Yu  Jingyun Ding  Jia Luo  Jiangnan Sun  Fangyuan Hu  Yaqing Chang  Chong Zhao 《Marine Ecology》2020,41(4):e12593

The detection of light intensity and subsequent phototaxis are essential for the fitness of sea urchins in intertidal and shallow subtidal waters, where light intensity varies in accordance with the depth and other hydrographic conditions. The molecular basis of photoresponse, however, remains largely unknown. We compared the expression of SiOpsin4, SiPax6, and SiOpsin5 among tube feet, coelomocytes, gonads, and gut of the sea urchin Strongylocentrotus intermedius. All three genes showed the significantly highest expression in tube feet. To test whether r-opsin genes (for example, Opsin4) and Pax6 in tube feet, rather than chaopsin genes (for example, Opsin5), are involved in the molecular responses to light intensity, we investigated the expression of Opsin4, Pax6, and Opsin5 among four light intensities. Both Opsin4 and Pax6 expressions were significantly higher in the sea urchins at 1,500 lx than at 100, 300, and 700 lx, indicating a co-upregulation of Opsin4 and Pax6 expressions in sea urchins exposed to the high light intensity (for example, 1,500 lx). However, there was no significant difference of SiOpsin5 expression among the four light intensity groups. Consistent with our hypothesis, there was no significant difference in either Opsin4 or Pax6 expression between the two light intensity environments (low light intensity environment: 50–100 lx; high light intensity environment: 330–1400 lx). This indicates that positive phototaxis and negative phototaxis probably regulate the expression of Opsin4 and Pax6 to a similar level when sea urchins are exposed to the high and low light intensities, respectively. The present study provides new insights into the molecular basis of light intensity detection and subsequent phototaxis of eyeless species.  相似文献   

6-DMAP诱导黄河口近江牡蛎(Crassostrea ariakensis)三倍体的研究     

李海昆  刘洋  李春华  王永旺  于瑞海 《海洋与湖沼》2020,51(5):1194-1202

用6-二甲基氨基嘌呤(6-DMAP)进行了黄河口近江牡蛎(Crassostreaariakensis)的三倍体诱导,以卵裂率、孵化率、诱导三倍体率和三倍体诱导组幼虫的生长率、存活率、三倍体率为指标,研究了诱导浓度、起始诱导时间、诱导持续时间三个因素对黄河口近江牡蛎三倍体的诱导效果。结果表明,三因素对近江牡蛎三倍体诱导效果的影响程度为起始诱导时间诱导持续时间诱导浓度。温度25℃,诱导浓度为300—450μmol/L,起始诱导时间为受精后14min,诱导持续时间为15min时,诱导三倍体率可达51.39%—71.67%,卵裂率、孵化率、幼虫壳高日平均生长率和幼虫平均存活率分别能达到65.16%—81.57%、61.25%—86.78%、8.76—9.88μm/d、69.16%—73.29%,眼点幼虫时期三倍体率达53.33%—62.16%。本研究为黄河口近江牡蛎的三倍体诱导提供了理论依据。  相似文献   

F油田长6超低渗油藏主要开发问题及技术对策     

刘军全 《海洋地质译丛》2010,(4):92-98

F油田长6油藏是鄂尔多斯盆地内较早开发并具规模的超低渗油藏。为了提高开发效果,解决开发中的问题和矛盾,通过矿场开发实践,较为系统地总结了长6油藏开发中所应用的8项技术,并对各项技术的应用效果进行了评价。通过这些技术的矿场应用,油藏的开发达到了较为理想的开发效果。  相似文献   

GF-6影像应用于林地与非林地识别的潜力分析     

刘代超  李晓松  李向晨  杨广斌  杨珺婷 《测绘通报》2020,(8):5

为研究我国首颗携带红边波段的高分六影像（GF-6）在林地与非林地上的识别贡献,本文选择复杂林地类型的安徽省黄山市作为研究区,采用特征优选（RFE）与随机森林（RF）相结合的方法开展了林地与非林地识别潜力研究。首先根据实地调查、Google Earth影像及林地"一张图"样本数据构建了样本库;然后基于DEM、多时相光谱特征、植被指数、红边指数等特征开展分类,并比较不同模型精度及不同变量的重要度。结果表明：GF-6红边信息对林地非林地识别较为重要,引入红边信息可将总体分类精度提升2%,其他新增波段及地形特征对林地与非林地识别贡献并不明显;多时相数据的运用相比单时相数据可整体提高林地类型的分类精度2.93%~4.1%,单时相分类结果6月最好,9月次之,12月最差;特征优选可以有效减少数据输入维数（46到15）,并取得最高分类精度,在不牺牲精度的同时保证了运算数据量的减少且明确了不同变量的贡献,具有较强的应用意义。  相似文献