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71.
<正>In the original article, the name of the fourth author is incorrect. The correct one is Kyoung Ho Kang, in which "Kang" is the family name. The publishing companies apologize to the author. 相似文献
72.
73.
A variety of soft‐sediment deformation structures formed during or shortly after deposition occurs in the Cretaceous Seongpori and Dadaepo Formations of the southeastern Gyeongsang Basin exposed along coastal areas of southeastern Korean Peninsula for 0.5–2 km. These are mostly present in a fluvial plain facies, with interbedded lacustrine deposits. In this study, the features of different kinds of soft‐sediment deformation structures have been interpreted on the basis of sedimentology of structure‐bearing deposits, comparison with normal sedimentary structures, timing and mechanism of deformation, and triggering mechanisms. The soft‐sediment deformation structures can be classified into four morphological groups: (i) load structures (load casts, ball‐and‐pillow structures); (ii) soft‐sediment intrusive structures (dish‐and‐pillars, clastic dykes, sills); (iii) ductile disturbed structures (convolute folds, slump structures); and (iv) brittle deformation structures (syndepositional faulting, dislocated breccia). The most probable triggering mechanisms resulting in these structures were seismic shocks. These interpretations are based on the following field observations: (i) location of the study area within tectonically active fault zone reactivated several times during the Cretaceous; (ii) deformation structures confined to single stratigraphic levels; (iii) lateral continuity and occurrences of various soft‐sediment deformation structures in the deformed level over large areas; (iv) absence of depositional slope to indicate gravity sliding or slumping; and (v) similarity to the structures produced experimentally. The soft‐sediment deformation structures in the study areas are thus interpreted to have been generated by seismic shocks with an estimated magnitude of M > 5, representing an intermittent record of the active tectonic and sedimentary processes during the development and evolution of two formations from the late Early Cretaceous to the Late Cretaceous. 相似文献
74.
Xiaodong Zhang Ho Jin Kim Clinton Streeter David A. Claypool Ramesh Sivanpillai Santhosh Seelan 《国际地球制图》2013,28(7):537-551
Precision agriculture often relies on high-resolution imagery to delineate the variability within a field. Airborne Environmental Research Observational Camera (AEROCam) was designed to meet the needs of agriculture producers, ranchers, and researchers, who require high-resolution imagery in a near real-time environment for rapid decision support. AEROCam was developed and operated through a unique collaboration between several departments at the University of North Dakota, including the Upper Midwest Aerospace Consortium (UMAC), the School of Engineering and Mines, and flight operations at the John D. Odegard School of Aerospace Sciences. AEROCam consists of a Redlake MS4100 area-scan multi-spectral digital camera that features a 1920 × 1080 CCD array (7.4-μm detector) with 8-bit quantization. When operated at ~2 km above ground level, multispectral images with four bands in the visible and near infrared have a ground sample distance of 1 m with a horizontal extent of just over 1.6 km. Depending on the applications, flying at different altitudes can adjust the spatial resolution from 0.25 to 2 m. Rigorous spectral and radiometric calibrations allow AEROCam to be used in a variety of applications, qualitative and quantitative. Equipped with an inertial measurement unit (IMU) system, the images acquired can be geo-referenced automatically and delivered to end users near real time through our Digital Northern Great Plains system (DNGP). The images are also available to zone mapping application for precision farming (ZoneMAP), an online decision support tool for creating management zones from remote sensing imagery and data from other sources. Operational since 2004, AEROCam has flown over 250 sorties and delivered over 150,000 images to the users in the Northern Great Plains region, resulting in numerous applications in precision agriculture and resource management. 相似文献
75.
Juan M. Jiménez Kazimierz Więski Laurie B. Marczak Chuan-Kai Ho Steven C. Pennings 《Estuaries and Coasts》2012,35(2):475-485
Top–down and bottom–up effects interact to structure communities, especially in salt marshes, which contain strong gradients
in bottom–up drivers such as salinity and nutrients. How omnivorous consumers respond to variation in prey availability and
plant quality is poorly understood. We used a mesocosm experiment to examine how salinity, nutrients, an omnivore (the katydid
Orchelimum fidicinium) and an herbivore (the planthopper Prokelisia spp.) interacted to structure a simplified salt marsh food web based on the marsh grass Spartina alterniflora. Bottom–up effects were strong, with both salinity and nutrients decreasing leaf C/N and increasing Prokelisia abundance. Top–down effects on plants were also strong, with both the herbivore and the omnivore affecting S. alterniflora traits and growth, especially when nutrients or salt were added. In contrast, top–down control by Orchelimum of Prokelisia was independent of bottom–up conditions. Orchelimum grew best on a diet containing both Spartina and Prokelisia, and in contrast to a sympatric omnivorous crab, did not shift to an animal-based diet when prey were present, suggesting
that it is constrained to consume a mixed diet. These results suggest that the trophic effects of omnivores depend on omnivore
behavior, dietary constraints, and ability to suppress lower trophic levels, and that omnivorous katydids may play a previously
unrecognized role in salt marsh food webs. 相似文献
76.
Sequential extraction and leaching characteristics of heavy metals in abandoned tungsten mine tailings sediments 总被引:1,自引:0,他引:1
Pyeong-Koo Lee Min-Ju Kang Ho Young Jo Sang-Hoon Choi 《Environmental Earth Sciences》2012,66(7):1909-1923
The chemical speciation of potentially toxic elements (As, Cd, Cu, Pb, and Zn) in the contaminated soils and sulfides-rich tailings sediments of an abandoned tungsten mine in Korea was evaluated by conducting modified BCR sequential extraction tests. Kinetic and static batch leaching tests were also conducted to evaluate the potential release of As and other heavy metals by acidic rain water and the leaching behaviors of these heavy metals. The major sources of the elements were As-, Zn- and Pb-bearing sulfides, Pb carbonates (i.e., cerussite), and Pb sulfates (i.e., anglesite). The biggest pollutant fraction in these soil and tailing samples consists of metals bound to the oxidizable host phase, which can be released into the environment if conditions become oxidative, and/or to residual fractions. No significant difference in total element concentrations was observed between the tailings sediments and contaminated soils. For both sample types, almost no changes occurred in the mobility of As and the other heavy metals at 7 days, but the mobility increased afterwards until the end of the tests at 30 days, regardless of the initial pH. However, the mobility was approximately 5–10 times higher at initial pH 1.0 than at initial pHs of 3.0 and 5.0. The leached amounts of all the heavy metal contents were higher from tailings sediments than from contaminated soils at pH > 3.0, but were lower at pH < 3.0 except for As. Results of this study suggest that further dissolution of heavy metals from soil and tailing samples may occur during extended rainfall, resulting in a serious threat to surface and groundwater in the mine area. 相似文献
77.
Su-Jong Jeong Chang-Hoi Ho Tae-Won Park Jinwon Kim Samuel Levis 《Climate Dynamics》2011,37(3-4):821-833
This study examines the potential impact of vegetation feedback on the changes in the diurnal temperature range (DTR) due to the doubling of atmospheric CO2 concentrations during summer over the Northern Hemisphere using a global climate model equipped with a dynamic vegetation model. Results show that CO2 doubling induces significant increases in the daily mean temperature and decreases in DTR regardless of the presence of the vegetation feedback effect. In the presence of vegetation feedback, increase in vegetation productivity related to warm and humid climate lead to (1) an increase in vegetation greenness in the mid-latitude and (2) a greening and the expansion of grasslands and boreal forests into the tundra region in the high latitudes. The greening via vegetation feedback induces contrasting effects on the temperature fields between the mid- and high-latitude regions. In the mid-latitudes, the greening further limits the increase in T max more than T min, resulting in further decreases in DTR because the greening amplifies evapotranspiration and thus cools daytime temperature. The greening in high-latitudes, however, it reinforces the warming by increasing T max more than T min to result in a further increase in DTR from the values obtained without vegetation feedback. This effect on T max and DTR in the high latitude is mainly attributed to the reduction in surface albedo and the subsequent increase in the absorbed insolation. Present study indicates that vegetation feedback can alter the response of the temperature field to increases in CO2 mainly by affecting the T max and that its effect varies with the regional climate characteristics as a function of latitudes. 相似文献
78.
Marine waters from seven sites around Hong Kong with varying levels of sewage pollution were analyzed for Hepatitis A virus (HAV) by PCR cloning and DNA sequencing of the highly variable VP1/2A junction of the HAV genome. Phylogenetic analysis of 10 PCR clones from each of the HAV-positive marine sites indicated that human HAV genotype IB is the most widely distributed type in Hong Kong waters. A sensitive and quantitative TaqMan-based PCR method targeting the 5′-noncoding region (5′-NCR) of HAV was used to quantify HAV particles in marine water samples along with the total Escherichiacoli counts being enumerated on TBX medium for comparison. Our results showed that no correlation of any significance between HAV and E. coli counts was observed which underscores the inadequacy in using E. coli as a sanitary standard to predict the levels of HAV in marine waters. 相似文献
79.
Air–water gas exchange is an important process in aquatic systems, including tidal rivers and estuaries. While there are now
reliable and routine methods for determining gas exchange over a range of temporal and spatial scales in the ocean and these
measurements have resulted in widely used wind speed parameterizations to calculate air–sea gas exchange, the same has not
been true for coastal inland waterways. Some studies have suggested that this difference is methodological, while others point
to the existence of additional drivers for gas exchange besides wind in rivers and estuaries. Here, we present gas transfer
velocities measured in the tidal Hudson River with a method widely used in oceanic studies, the 3He/SF6 dual tracer technique. Airside and waterside forcings were determined with an anemometer and an acoustic Doppler current
profiler, respectively. The results confirm that wind is the dominant driver of gas exchange in the tidal Hudson River, with
negligible contribution from bottom-generated turbulence. Furthermore, a parameterization between wind speed and gas exchange
developed for the ocean is able to predict gas exchange in this environment with high accuracy. It is hoped that by transferring
methodology used in oceanic studies to rivers and estuaries, robust data can be obtained that will eventually allow development
of widely applicable relationships between easily measured environmental variables and gas exchange in tidal inland waters. 相似文献
80.
Min Kyung Lee Yong Il Lee Hyoun Soo Lim Jae Il Lee Jeong Heon Choi Ho Il Yoon 《Journal of Paleolimnology》2011,45(2):127-135
Both radiocarbon and optically stimulated luminescence (OSL) dating methods were applied to test their suitability for establishing
a chronology of arid-zone lacustrine sediments using a 5.88-m-long core drilled from Lake Ulaan, southern Mongolia. Although
the radiocarbon and OSL ages agree in some samples, the radiocarbon ages are older than the corresponding OSL ages at the
550-cm depth horizon (late Pleistocene) and in the 100–300-cm interval (early to late Holocene). In the early to late Holocene,
radiocarbon ages are consistently older than OSL ages by 4,100–5,800 years, and in the late Pleistocene by 2,700–3,000 years.
Grain-size analysis of early to late Holocene sediments and one late Pleistocene sediment sample (550-cm depth) indicates
that eolian processes were the dominant sediment-transport mechanism. Also, two late Pleistocene sediments samples (from 400-
to 500-cm depths) are interpreted to have been deposited by both eolian and glaciofluvial processes. Accordingly, the radiocarbon
ages that were older than the corresponding OSL ages during the Holocene seem to have been a consequence of the influx of
14C-deficient carbon delivered from adjacent soils and Paleozoic carbonate rocks by the westerly winds, a process that is also
active today. In addition to the input of old reworked carbon by eolian processes, the late Pleistocene sediments were also
influenced by old carbon delivered by deglacial meltwater. The results of this study suggest that when eolian sediment transport
is suspected, especially in lakes of arid environments, the OSL dating method is superior to the radiocarbon dating method,
as it eliminates a common ‘old-carbon’ error problem. 相似文献