A large-mesh salmon trap: a way of mitigating seal impact on a coastal fishery   总被引：1，自引：2，他引：1  

Lunneryd  Sven Gunnar; Fjalling  Arne; Westerberg  Hakan 《ICES Journal of Marine Science》2003,60(6):1194-1199

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Identifying drivers for fishing pressure. A multidisciplinary study of trawl and sea snail fisheries in Samsun,Black Sea coast of Turkey     

Ståle Knudsen  Mustafa Zengin  Mahmut Hakan Koçak 《Ocean & Coastal Management》2010,53(5-6):252-269

This study aims to investigate and model driving forces that lead to increased fishing pressure and an altered state of the environment in the coastal areas near Samsun on the Turkish Black Sea coast. We have applied a modified DPSIR model to structure our investigation and analysis and have investigated the drivers that generate fishing pressure in the Samsun fisheries. The overall health of the ecosystem is declining, and there is a consistent trend of deterioration in the condition of the three major species targeted by the trawl fisheries. Although introduced invasive species have brought significant changes to the Black Sea, it is clear that the state of the environment is significantly and negatively affected by the pressure exerted by fisheries. Fishing pressure has to a certain extent been redirected to pelagic trawling as bottom trawling has become less profitable and a rise in catch capacity has levelled off. This reduction is, however, offset by an increase in illegal trawling and dredging by a very rapidly growing sector of multi-purpose small boats, resulting in a considerable increase in the overall accumulated engine power of fishing boats in Samsun during 2000–2005. Fisheries in Samsun, in particular sea snail fisheries, have constituted a frontier of sorts open to the poorer populations of Samsun during the last 20 years, and, thereby, constitute one of the major drivers for fishing pressure. We identify eight drivers of importance for the period 2000–2005. Although the authorities can impact all or most of those drivers, most of them are beyond the scope of conventional ‘fisheries management’.  相似文献   

Geochemical, mineralogical and isotopic signatures of the Semikan, West Kasrık “Turkish” phosphorites from the Derik–Mazıdağı–Mardin area, SE Anatolia     

M. Sefik Imamoglu  Yaacov Nathan  Hakan Çoban  David Soudry  Craig Glenn 《International Journal of Earth Sciences》2009,98(7):1679-1690

The geochemistry and mineralogy of a condensed section, ~6 m thick of the West Kasrik member (Coniacian–Santonian) near the uplifted northern flank of the Mardin–Derik anticline (south-eastern Turkey) was studied. The only deposit exploited in Turkey is found in this area. The sediment textures as well as the mineralogical and the geochemical results collectively suggest that these recycled phosphorites accumulated in areas of intensive very early diagenesis of the sediments in highly oxic bottom waters, and almost no detrital apport. The total concentration of redox-sensitive trace metals is very low (<600 μg/g); in addition the structural CO₂ and F/P₂O₅ are unusually high (~5 wt % and 0.14, respectively). REE distribution shows a clear “seawater” pattern with a strongly negative Ce-anomaly (0.20 ± 0.02) and heavy REE enrichment (Lu_N/La_N = 1.50 ± 0.12), however their total concentration is very low. The low REE contents, quite unexpected in recycled phosphorites, are explained by the scarcity of terrigenous components which leads to minimal incorporation of REEs from detrital clastic phases in the CFA fraction. Weathering previously suggested as responsible for the high P enrichment of the Mazidagi phosphorites is rather improbable in the samples we studied, in view of their high structural CO₂, high F/P₂O₅, high (La/Nd)_N and (La/Sm)_N ratios, and high Sr/P and Ca/P of separated CFA fractions that all negate post-depositional weathering. More likely, the high P enrichment of some rocks (P₂O₅ content reaches 34%) was produced by sedimentary and early diagenetic processes acting in oxygenated areas of starved sedimentation on and around tectonic highs.  相似文献   

Landslide susceptibility mapping for a part of tectonic Kelkit Valley (Eastern Black Sea region of Turkey)   总被引：19，自引：1，他引：18  

Hakan A. Nefeslioglu  Tamer Y. Duman  Serap Durmaz 《Geomorphology》2008,94(3-4):401

Considering damage to man-made structures by natural hazards in Turkey, landslides are the second most important hazard after earthquakes. For this reason, a large-scale study titled Turkish Landslide Inventory Project, has been carried out since 1998. During this project, some special, susceptibility, hazard and risk assessments have been performed. In this study, a landslide susceptibility map of a part of tectonic Kelkit Valley in the north of central Turkey was produced, employing binary logistic regression analyses. To achieve the most appropriate results some sensitivity analyses were also carried out. For this purpose, four different data sets were constructed considering conditioning factors used and sampling strategies applied for the training data sets in this study. As a consequence of the analyses, the most proper outcomes were obtained by using the data set in which continuous topographical parameters and lithological dummy variables were implemented together and 50% of training data set was taken from seed cells at random. Correct classification percentage and Root Mean Square Error (RMSE) values for the validation data for that case were estimated as 84.16% and 0.36, respectively. This prediction capability shows that the landslide susceptibility map produced in this research paper can be used for the planning of protective and mitigation measures in the region.  相似文献   

Removal of Fluoride from Aqueous Solution Using Aluminum Alginate Beads          下载免费PDF全文

Hakan Kaygusuz  Sesil Uzaşçı  F. Bedia Erim 《洁净——土壤、空气、水》2015,43(5):724-730

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Impact of Urbanization on Local Air Quality: Differences in Urban and Rural Areas of Balikesir,Turkey          下载免费PDF全文

Lokman Hakan Tecer  Sermin Tagil 《洁净——土壤、空气、水》2014,42(11):1489-1499

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A numerical study on response factors for steel wall–frame systems     

Hakan Arslan  Cem Topkaya 《地震工程与结构动力学》2010,39(14):1611-1630

A numerical investigation was undertaken to evaluate the response of dual structural systems that consisting of steel plate shear walls and moment‐resisting frames. The primary objective of the study was to investigate the influence of elastic base shear distribution between the wall and the frame on the global system response. A total of 10 walls and 30 wall–frame systems, ranging from 3 to 15 stories, were selected for numerical assessment. These systems represent cases in which the elastic base shear resisted by the frame has a share of 10, 25, or 50% of the total base shear resisted by the dual system. The numerical study consisted of 1600 time history analyses employing three‐dimensional finite elements. All 40 structures were separately analyzed for elastic and inelastic response by subjecting them to the selected suite of earthquake records. Interstory drifts, top story drift, base shears resisted by the wall, and the frame were collected during each analysis. Based on the analysis results, important response quantities, such as the strength reduction, the overstrength, and the displacement amplification factors, are evaluated herein. Results are presented in terms of displacement measures, such as the interstory drift ratio and the top story drift ratio. Analysis results revealed that the increase in the strength reduction factor with the amount of load share is insignificant. Furthermore, there is an inverse relationship between the ductility reduction and the overtsrength. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Ecological risk assessment using trace elements from surface sediments of Izmit Bay (Northeastern Marmara Sea) Turkey   总被引：16，自引：0，他引：16  

Pekey H  Karakaş D  Ayberk S  Tolun L  Bakoğlu M 《Marine pollution bulletin》2004,48(9-10):946-953

The aim of this study was to study ecological risk assessment of trace elements (As, Cd, Cr, Cu, Ni, Pb and Zn) in Izmit Bay surface sediments in the <63 microm fraction. Sediment samples were collected from 8 sites along the north coastline of the bay. Samples were subjected to a total digestion technique and analyzed for major (organic carbon) and minor (As, Cd, Cr, Cu, Ni, Pb and Zn) elements. Sediments heavily contaminated are evaluated by the Sediment Quality Guidelines (SQG) of US EPA. The degree of contamination (Cd) is estimated as very high at each site. Two sets of SQGs, effect range-low/effect range median values and TEL/probable effect level (PEL) values were used in our study. Sediments from the each site are judged toxic when two or more of the PEL values exceed EPA guidelines. Our results are in agreement with previously reported sediment toxicity test results.  相似文献   

Mineral phase compositions in silica-undersaturated ‘leucite’ lamproites from the Bucak area, Isparta, SW Turkey     

Hakan oban  Martin F.J. Flower 《Lithos》2006,89(3-4):275-299

Ultrapotassic rocks in the Bucak area of Isparta Angle, SW Turkey, show unusually low SiO₂ (46.8–49.2 wt.%) and high MgO (10.4–11.6 wt.%) contents, and lamproitic affinity (K/Na, > 2.5; Mg#, 73–75; Al₂O₃, 9.2–11 wt.%, CaO 7.4–10.6 wt.%, Cr, 525–675 ppm; Ni, 442–615 ppm). They are made up by phlogopite (30–40 vol.%), leucite (25–30 vol.%), olivine (5–20 vol.%), which rarely contain Cr-spinel, clinopyroxene (5–10 vol.%), sanidine (5 vol.%) and richterite, with accessory apatite, magnetite and ilmenite. One sample also include negligible sodalite in groundmass, which is unusual mineral in lamproites. Mineral phase variation and textures record discrete phases of pre-eruptive crystallization: (1) early appearance of (Cr-spinel-bearing) olivine, Ti poor phlogopite ± apatite at pressures of ca. 1.0–2.0 GPa, at or close to the lithospheric Mechanical Boundary Layer (MBL), and (2) later appearance of Ti rich phlogopite, clinopyroxene, richterite, leucite, sanidine, and other minor phases, at pressures of ca. 0.1–1.0 GPa, indicating discrete, pressure-specific fractionation events. The Bucak silica poor ‘leucite’ lamproites were probably generated by partial melting of phlogopite-bearing, refractory peridotite at pressures of ca. 1.5–2 GPa, higher than those proposed for SiO₂-saturated ‘phlogopite’ lamproites (ca. 1–1.5 GPa) from Afyon, to the North. The depth (total pressure) of melt segregation probably dominates over volatile partial pressures (e.g. of CO₂, F, H₂O) in determining the SiO₂-undersaturated character of Bucak magmas.  相似文献   

Impact of complexity on daily and multi-step forecasting of streamflow with chaotic,stochastic, and black-box models   总被引：1，自引：0，他引：1  

Hakan?TongalEmail author  Ronny?Berndtsson 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(3):661-682

Despite significant research advances achieved during the last decades, seemingly inconsistent forecasting results related to stochastic, chaotic, and black-box approaches have been reported. Herein, we attempt to address the entropy/complexity resulting from hydrological and climatological conditions. Accordingly, mutual information function, correlation dimension, averaged false nearest neighbor with E1 and E2 quantities, and complexity analysis that uses sample entropy coupled with iterative amplitude adjusted Fourier transform were employed as nonlinear deterministic identification tools. We investigated forecasting of daily streamflow for three climatologically different Swedish rivers, Helge, Ljusnan, and Kalix Rivers using self-exciting threshold autoregressive (SETAR), k-nearest neighbor (k-nn), and artificial neural networks (ANN). The results suggest that the streamflow in these rivers during the 1957–2012 period exhibited dynamics from low to high complexity. Specifically, (1) lower complexity lead to higher predictability at all lead-times and the models’ worst performances were obtained for the most complex streamflow (Ljusnan River), (2) ANN was the best model for 1-day ahead forecasting independent of complexity, (3) SETAR was the best model for 7-day ahead forecasting by means of performance indices, especially for less complexity, (4) the largest error propagation was obtained with the k-nn and ANN and thus these models should be carefully used beyond 2-day forecasting, and (5) higher number input variables except for the dominant variables made insignificant impact on forecasting performances for ANN and k-nn models.  相似文献