Validation of MODIS Vegetation Continuous Fields for monitoring deforestation and forest degradation: two cases in Mexico     

Yan Gao  Adrian Ghilardi  Jaime Paneque-Galvez  Margaret Skutsch  Jean François Mas 《国际地球制图》2016,31(9):1019-1031

This study assesses whether MODIS Vegetation Continuous Fields percent tree cover (PTC) data can detect deforestation and forest degradation. To assess the usefulness of PTC for detecting deforestation, we used a data set consisting of eight forest and seven non-forest categories. To evaluate forest degradation, we used data from two temperate forest types in three conservation states: primary (dense), secondary (moderately degraded) and open (heavily degraded) forest. Our results show that PTC can differentiate temperate forest from non-forest categories (p = 0.05) and thus suggests PTC can adequately detect deforestation in temperate forests. In contrast, single-date PTC data does not appear to be adequate to detect forest degradation in temperate forests. As for tropical forest, PTC can partially discriminate between forest and non-forest categories.  相似文献   

A database for fatalities and damages due to the earthquakes in Turkey (1900–2014)     

Murat Bikçe 《Natural Hazards》2016,83(3):1359-1418

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Ontogenic variation and effect of collection procedure on leaf biomechanical properties of Mediterranean seagrass Posidonia oceanica (L.) Delile          下载免费PDF全文

Carmen B. de los Santos  Bárbara Vicencio‐Rammsy  Gilles Lepoint  François Remy  Tjeerd J. Bouma  Sylvie Gobert 《Marine Ecology》2016,37(4):750-759

Leaf mechanical traits are important to understand how aquatic plants fracture and deform when subjected to abiotic (currents or waves) or biotic (herbivory attack) mechanical forces. The likely occurrence of variation during leaf ontogeny in these traits may thus have implications for hydrodynamic performance and vulnerability to herbivory damage, and may be associated with changes in morphologic and chemical traits. Seagrasses, marine flowering plants, consist of shoot bundles holding several leaves with different developmental stages, in which outer older leaves protect inner younger leaves. In this study we examined the long‐lived seagrass Posidonia oceanica to determine ontogenic variation in mechanical traits across leaf position within a shoot, representing different developmental stages. Moreover, we investigated whether or not the collection procedure (classical uprooted shoot versus non‐destructive shoot method: cutting the shoot without a portion of rhizome) and time span after collection influence mechanical measurements. Neither collection procedure nor time elapsed within 48 h of collection affected measurements of leaf biomechanical traits when seagrass shoots were kept moist in dark cool conditions. Ontogenic variation in mechanical traits in P. oceanica leaves over intermediate and adult developmental stages was observed: leaves weakened and lost stiffness with aging, while mid‐aged leaves (the longest and thickest ones) were able to withstand higher breaking forces. In addition, younger leaves had higher nitrogen content and lower fiber content than older leaves. The observed patterns may explain fine‐scale within‐shoot ecological processes of leaves at different developmental stages, such as leaf shedding and herbivory consumption in P. oceanica.  相似文献   

Late Cretaceous–Cenozoic subduction–collision history of the Southern Neotethys: new evidence from the Çağlayancerit area,SE Turkey     

Ahmet Can Akıncı  Alastair H. F. Robertson  Ulvi Can Ünlügenç 《International Journal of Earth Sciences》2016,105(1):315-337

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The investigation of static and dynamic capillary by water absorption in porous building stones under normal and salty water conditions     

Mustafa Yavuz Çelik  Ahmet Uğur Kaçmaz 《Environmental Earth Sciences》2016,75(4):307

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Site characterization of the strong motion stations and evaluation of site effects in the Ankara region during the December 2007 and March 2008 moderate Bala earthquakes     

Mustafa Kerem Koçkar 《Environmental Earth Sciences》2016,75(15):1128

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An integration-based estimation approach for the determination of slug test parameters under various flow geometries     

A. Ufuk Şahin  Emin Çiftçi 《Arabian Journal of Geosciences》2016,9(14):639

A simple parameter estimation procedure, designated as integration-based estimation (IBE), was introduced to determine the hydraulic properties of an aquifer using slug test models subjected to certain flow geometries such as radial and spherical flows. The basic idea behind the proposed IBE approach is to link an integration value at pre-defined normalized head levels for field data with that of a theoretical type curve. The IBE method removes the need for the implementation of the classical graphical matching process which would be ineffective to acquire aquifer parameters for non-ideal aquifer conditions. As the second aspect of this study, a new decision tool was suggested to determine the suitable slug test model to be utilized for the site data since diagnosing the flow character properly is of crucial importance for following a convenient analysis procedure. The estimation performance and limitation of the proposed IBE method were tested for several slug test scenarios including radial and spherical flow models with a number of synthetically generated data sets as well as a field application. Results reveal that the IBE together with the identification methodology not only is able to retrieve aquifer parameters as reliable as the existing techniques in the literature but also diagnoses the flow character precisely as demonstrated in this study.  相似文献   

Soil wettability in ground engineering: fundamentals,methods, and applications     

S. D. N. Lourenço  Y. Saulick  S. Zheng  H. Kang  D. Liu  H. Lin  T. Yao 《Acta Geotechnica》2018,13(1):1-14

Wettability is a fundamental property controlling the extent of wetting in flat and granular solids. In natural soils, wettability affects a wide variety of processes including infiltration, preferential flow and surface runoff. In mineral processing, wettability is paramount in enhancing the efficiency of separation of minerals from gangue. The manipulation of surface wettability is equally crucial in many industrial applications. For instance, superhydrophobic surfaces are those on which water drops roll off easily and as such are used for self-cleaning applications. Therefore, while wettability is strongly cross-disciplinary, its evolution has been discipline-specific with a direct extrapolation or transfer of concepts, approaches, and methods to ground engineering unlikely to remain valid. This paper synthesizes relevant aspects from surface chemistry, materials science, mining engineering, and soil science, and discusses their implications within the context of new granular materials that resist wetting, for use in barriers or ground improvement and, in unsaturated soils, where the effects of wettability have been documented.  相似文献   

Geochemistry of Çoruh River Bed Sediments in NE Turkey: Implications in Weathering-Sedimentary Cycle,Provenance, and Metal Pollution     

Ç. Saydam Eker  E. Demirkol Kiliç 《Geochemistry International》2018,56(6):579-600

This study defines the source area, sub-aerial weathering, and sedimentary cycle level, as well as heavy metal content and origin, of the Çoruh River bed sediments. The studied sediments are geochemically classified as litharenite based on the ratio of the major element contents. Relative to the Upper Continental Crust (UCC), trace elements Rb, Sr, Ba, Th, U, Zr, Hf, Y, Nb, and Pb are generally depleted; Co, Ni, Cu, Sc, and V are generally enriched; and Au is depleted in some places and enriched in other places. The rare earth element (REE) distributions of the samples exhibit a trend similar to that of the upper continental crust (UCC); however, low to moderate depletion occurs in the bed sediments in UCC. The analyzed samples exhibit low Chemical Index of Alteration (CIA) values, Plagioclase Index of Alteration (PIA) values (<50), CIA/WIP (Weathering Index ratios <1), and substantially high Index of Compositional Variability values (ICV) (>1). Thus, the samples are not chemically mature and are mainly derived from non-altered sources and were exposed the simple cycling history. REEs are depleted in the river bed sediments, unlike the world river average silt, world river average clay, and suspended sediment in world rivers. Minor enrichment of Zn, Sn, and Sc contents, low-to-moderate enrichment of Cu content, very severe enrichment of as content, and extremely severe enrichment of Ni content of the analyzed samples are observed. Consequently, stream bed sediments are derived from intermediate sources close to mid-continental crust rather than felsic sources Low-to-moderate degrees of chemical weathering of these sediments indicate increased tectonic activity, increased erosion, and rapid sedimentation in semiarid to arid conditions in the source regions over time. Thus, the sediments are chemically immature. These sediments are exposed to lithogenic and anthropogenic contamination.  相似文献   

Petrogenesis of plio-quaternary intra-plate continental alkaline lavas from the İskenderun Gulf (Southern Turkey): Evidence for metasomatized lithospheric mantle     

Aykut Güçtekin 《Chemie der Erde / Geochemistry》2018,78(4):521-534

The Quaternary alkaline volcanic field of Southern Turkey is characterized by intra-continental plate-type magmatic products, exposed to the north of the ?skenderun Gulf along a NE-SW trending East Anatolian Fault, to the west of its intersection with the N–S trending Dead Sea Fault zone. The ?skenderun Gulf alkaline rocks are mostly silica-undersaturated with normative nepheline and olivine and are mostly classified as basanites and alkaline basalts with their low-silica contents ranging between 43 and 48?wt.% SiO₂. They display Ocean Island Basalt (OIB)–type trace element patterns characterized by enrichments in large-ion-lithophile elements (LILE) and light rare earth element (LREE), and have (La/Yb)_N?=?8.8–17.7 and (Hf/Sm)_N?=?0.9–1.6 similar to those of basaltic rocks found in intraplate suites. The basanitic rocks have limited variations Sr-Nd isotopic ratios (⁸⁷Sr/⁸⁶Sr?=?0.70307–0.70324, ¹⁴³Nd/¹⁴⁴Nd?=?0.512918–0.521947), whereas the alkali basalts display more evolved Sr-Nd isotopic ratios (⁸⁷Sr/⁸⁶Sr?=?0.70346-0.70365, ¹⁴³Nd/¹⁴⁴Nd?=?0.512887–0.521896). The ?skenderun Gulf alkaline rocks also display limited Pb isotopic variations with ²⁰⁶Pb/²⁰⁴Pb?=?18.75–19.09 ²⁰⁷Pb/²⁰⁴Pb?=?15.61–15.66 and²⁰⁸Pb/²⁰⁴Pb?=?38.65–39.02, indicating that they originated from an enriched lithospheric mantle source. Calculated fractionation vectors indicate that clinopyroxene and olivine are the main fractionating mineral phases. Similarly, based on Sr-Nd isotopic ratios, the assimilation and fractional crystallization (AFC) modeling shows that the alkali basalts were affected by AFC processes (r?=?0.2) and were slightly contaminated by the upper crustal material.The high TiO₂ contents, enrichments in Ba and Nb, and depletions in Rb can likely be explained by the existence of amphibole in the mantle source, which might, in turn, indicate that the source mantle has been affected by metasomatic processes. The modeling based on relative abundances of trace elements suggests involvement of amphibole-bearing peridotite as the source material. ?skenderun Gulf alkaline rocks can thus be interpreted as the products of variable extent of mixing between melts from both amphibole-bearing peridotite and dry peridotite.  相似文献