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971.
The soil microbiome that plays important ecological roles in mountains and forests is influenced by anthropogenic and natural causes. Human activity, particularly harvesting or thinning, affects the soil microbiome in forests by altering environmental conditions, such as vegetation, microclimate, and soil physicochemical properties. The purpose of this study was to investigate the effects on forest thinning on the diversity and composition of the soil bacterial community. From next-generation sequencing results of the 16S rRNA gene, we examined differences in soil bacterial diversity and community composition before and after thinning at Mt. Janggunbong, South Korea. We identified 40 phyla, 103 classes, 192 orders, 412 families, 947 genera, and 3,145 species from the soil samples. Acidobacteria and Proteobacteria were the most dominant bacterial phyla in the forest soil of Mt. Janggunbong. Soil bacterial diversity measures (richness, Shannon diversity index, and evenness) at the phylum level increased after thinning, whereas species-level taxonomic richness decreased after thinning. Thinning provided new opportunities for bacterial species in Chloroflexi, Verrucomicrobia, Nitrospirae, and other nondominant bacterial taxa, especially for those not found in Mt. Janggunbong before thinning, to settle and adapt to the changing environment. Our results suggested that thinning affected the diversity and composition of soil bacterial communities in forests and mountains. 相似文献
972.
酪蛋白激酶1 (CK1)是一种重要的蛋白激酶家族,其在DNA损伤应答和修复、细胞增殖和凋亡、胚胎发育和稳态等重要的生物学过程中都具有复杂多样的调控作用。为了理解CK1基因家族在双壳贝类中的特征、进化及生物学功能,实验采用比较基因组学及生物信息学的方法对双壳贝类CK1基因家族进行了鉴定分析,通过虾夷扇贝高温应激实验,研究了CK1基因家族在高温应激时的表达规律。结果显示,在虾夷扇贝、栉孔扇贝、长牡蛎与侏儒蛤中均存在CK1α,CK1αlike,CK1δ,CK1γ3,并发现CK1ε,CK1γ1,CK1γ2在双壳贝类中发生了丢失。时空表达分析发现,双壳贝类CK1基因均在胚胎发育早期集中表达,并以多细胞/囊胚期为界呈现出母源/合子特异性表达模式。CK1为关键基因的基因共表达模块显著富集在错配修复、核苷酸剪切修复等相关通路上,暗示了CK1基因在双壳贝类胚胎发育过程中参与调控DNA损伤修复过程,从而维持早期胚胎发育时的基因组稳定性。双壳贝类CK1基因在成体中呈现组织特异的表达模式,主要在鳃和雄性性腺中具有相对较高的表达量。虾夷扇贝受到高温应激后,其鳃中PyCK1α, PyCK1αlike和PyCK1δ... 相似文献
973.
Solar filaments show the position of large-scale polarity-inversion lines and are used for the reconstruction of large-scale
solar magnetic field structure on the basis of Hα synoptic charts for the periods that magnetographic measurements are not
available. Sometimes crossing filaments are seen in Hα filtergrams. We analyze daily Hα filtergrams from the archive of Big
Bear Solar Observatory for the period of 1999 – 2003 to find crossing and interacting filaments. A number of examples are
presented and filament patterns are compared with photospheric magnetic field distributions. We have found that all crossing
filaments reveal quadrupolar magnetic configurations of the photospheric field and presume the presence of null points in
the corona. 相似文献
974.
Mapping the thickness of sediments in the Ljubljana Moor basin (Slovenia) using microtremors 总被引:2,自引:0,他引:2
The Ljubljana Moor basin is characterized by moderate bedrock topography and thicknesses of Quaternary lacustrine and fluvial
sediments ranging from 0 to 200 m. More than 65 boreholes which reached the bedrock were drilled in the area, but their distribution
in the basin is very uneven and some data from the boreholes uncertain. There are also no data on S-velocity distribution
within the basin, but seismic refraction measurements pointed out a rather uniform increase of P-velocity with depth, great
impedance contrast with the bedrock and relatively small lateral velocity variations. The microtremor horizontal-to-vertical
spectral ratio (HVSR) method was therefore applied as a complementary tool to seismic refraction survey to map the thickness
of sediments. First, microtremors were measured at the locations of boreholes which reached the bedrock and the resonance
frequencies determined. The inverse power relationship between the resonance frequency and the thickness of sediments was
then determined from 53 data pairs. The quality of the correlation is moderate due to possible heterogeneities in sediments
and possible 3D effects in some minor areas, but the obtained parameters correspond well to the values obtained in six other
European basins. Secondly, a 16 km-long discontinuous seismic refraction profile was measured across the whole basin, leaving
uncovered some larger segments where active seismic measurements were not possible. Microtremors were then measured at 64
locations along the same profile, using 250 m point spacing, without leaving any gaps. The frequency–thickness relationship
was used to invert resonance frequencies to depths. These were first validated using the results of the seismic refraction
survey, which showed good agreement, and finally used for interpolation in the segments of missing refraction data to obtain
a continuous depth profile of the bedrock. The study has shown that the microtremor method can be used as a complementary
tool for mapping the thickness of unconsolidated sediments also in areas characterized by moderate bedrock topography. As
the input data are always to some extent uncertain, it is important to have a sufficiently large number of borehole data to
establish a frequency–thickness relationship, as well as some additional independent geophysical information for its validation. 相似文献
975.
通过对南起中国内蒙古满都拉、向北经蒙古国、直抵北端俄罗斯贝加尔湖北卡楚加全长1320km长重力剖面的布格重力异常数据进行处理和解析, 依其构建了沿剖面的二维地壳密度结构模型, 并详细分析了沿剖面的地壳底界面(Moho界面)展布的深部构造特征, 及剖面辖域内的5个次级局部构造单元的重力异常场、地壳密度结构、界面起伏及断裂构造分布的特征.期望此研究结果能为该剖面跨越的中亚造山带东部地区的地壳结构、各次级构造单元的界域与关联方面的进一步研究提供相关的重力场依据.
相似文献976.
Correlation between molecular absorption spectral slope ratios and fluorescence humification indices in characterizing CDOM 总被引:2,自引:0,他引:2
Hao Chen Binghui Zheng Yonghui Song Yanwen Qin 《Aquatic Sciences - Research Across Boundaries》2011,73(1):103-112
Ultraviolet–visible absorption spectral slope ratios SR (slope in 275–295 nm divided by slope in 350–400 nm) and humification index (HIX, integrated fluorescence emission in 435–480 nm
divided by that in 435–480 and 300–345 nm) were compared when characterizing chromophoric dissolved organic matter (CDOM)
in three humic acids and 44 whole water samples. HIX increased with increasing pH for humic acids, while their SR showed much more complicated dependencies on pH. There was a negative correlation between SR and HIX. SR increased in the order terrestrial coal/peat < terrestrial soil/river < seawater, while HIX increased in the order seawater < terrestrial
soil/river < terrestrial coal/peat. The comparative study in this work indicates that terrestrially derived CDOM has higher
HIX and lower SR than marine CDOM. Investigators may potentially use these two indices to compare qualitatively the character of CDOM in different
sources (e.g., terrestrial vs. marine). 相似文献
977.
Mahmoud Hamlaoui K. Vanneste K. Baddari L. Louail B. Vleminckx A. Demdoum 《Arabian Journal of Geosciences》2017,10(11):238
This work involves updating the evaluation of seismic hazard in Northeast Algeria by a probabilistic approach. This reassessment attempts to resolve inconsistencies between seismic zoning in regional building codes and is further motivated by the need to refine the input data that are used to evaluate seismic hazard scenarios. We adopted a seismotectonic model that accounts for differences in interpretations of regional seismicity. We then performed a probabilistic assessment of regional seismic hazard in Northeast Algeria. Based on a homogeneous earthquake catalog and geological and seismotectonic data gathered in the first part of the study, a seismotectonic zoning map was created and seven risk areas were identified. For each area, peak ground acceleration hazard maps were produced. Details of the calculations are provided, including hazard curves at periods of 0.1, 0.2, 0.33, 0.5, 1.0, and 2.0 s and uniform hazard spectra at urban locations in the area, including Sétif, Constantine, Kherrata, Bejaia, and Jijel. 相似文献
978.
Tao Chen Christoph Clauser Gabriele Marquart Karen Willbrand Thomas Hiller 《Hydrogeology Journal》2018,26(6):1903-1916
Upscaling permeability of grid blocks is crucial for groundwater models. A novel upscaling method for three-dimensional fractured porous rocks is presented. The objective of the study was to compare this method with the commonly used Oda upscaling method and the volume averaging method. First, the multiple boundary method and its computational framework were defined for three-dimensional stochastic fracture networks. Then, the different upscaling methods were compared for a set of rotated fractures, for tortuous fractures, and for two discrete fracture networks. The results computed by the multiple boundary method are comparable with those of the other two methods and fit best the analytical solution for a set of rotated fractures. The errors in flow rate of the equivalent fracture model decrease when using the multiple boundary method. Furthermore, the errors of the equivalent fracture models increase from well-connected fracture networks to poorly connected ones. Finally, the diagonal components of the equivalent permeability tensors tend to follow a normal or log-normal distribution for the well-connected fracture network model with infinite fracture size. By contrast, they exhibit a power-law distribution for the poorly connected fracture network with multiple scale fractures. The study demonstrates the accuracy and the flexibility of the multiple boundary upscaling concept. This makes it attractive for being incorporated into any existing flow-based upscaling procedures, which helps in reducing the uncertainty of groundwater models. 相似文献
979.
Patrizia Köpfli Lorenz M. Grämiger Jeffrey R. Moore Christof Vockenhuber Susan Ivy-Ochs 《Swiss Journal of Geoscience》2018,111(1-2):205-219
Landslide deposits dam Lake Oeschinen (Oeschinensee), located above Kandersteg, Switzerland. However, past confusion differentiating deposits of multiple landslide events has confounded efforts to quantify the volume, age, and failure dynamics of the Oeschinensee rock avalanche. Here we combine field and remote mapping, topographic reconstruction, cosmogenic surface exposure dating, and numerical runout modeling to quantify salient parameters of the event. Differences in boulder lithology and deposit morphology reveal that the landslide body damming Oeschinensee consists of debris from both an older rock avalanche, possibly Kandertal, as well as the Oeschinensee rock avalanche. We distinguish a source volume for the Oeschinensee event of 37 Mm3, resulting in an estimated deposit volume of 46 Mm3, smaller than previous estimates that included portions of the Kandertal mass. Runout modeling revealed peak and average rock avalanche velocities of 65 and 45 m/s, respectively, and support a single-event failure scenario. 36Cl surface exposure dating of deposited boulders indicates a mean age for the rock avalanche of 2.3 ± 0.2 kyr. This age coincides with the timing of a paleo-seismic event identified from lacustrine sediments in Swiss lakes, suggesting an earthquake trigger. Our results help clarify the hazard and geomorphic effects of rare, large rock avalanches in alpine settings. 相似文献
980.
In situ Microphytobenthic community dynamics were combined with laboratory measurement of predominant species by fluorescence methods to estimate the areal primary production. Field investigation of community dynamics of microphytobenthos (MPB) was conducted from August 2006 to August 2007 in intertidal flats of the Nakdong River estuary, Korea. MPB Biomass varied between 0.47 and 16.58 μg cm?3 in the surface 1 cm sediment, with two dominant diatom species, Amphora coffeaeformis and Navicula sp., occupying average 77.2 ± 14.9% of total number of MPB cells. The biomass was higher in the slightly muddy sand sites than that in the sand site, and showed different pattern of seasonal variation. The profile of vertical distribution of biomass was an exponential decrease trend with depth in sediments. The biomass proportions in the uppermost 3 mm were 57.6% and 37.8% with and without the presence of biofilm, respectively. The two dominant species were cultured in laboratory, and their photosynthetic parameters, rETRmax (relative maximum electron transport rate), α (light utilization coefficient) and E k (light saturation parameter) were derived from rETR (relative ETR)-irradiance curves by Imaging- PAM (pulse amplitude modulated) fluorometry. The rETR-irradiance curves showed no significant difference of photosynthetic activities between the two species. The areal potential production ranged from 0.74 to 2.22 g C m?2 d?1. 相似文献