排序方式： 共有73条查询结果，搜索用时 31 毫秒
21.
Jonathan M. Abell Paul van Dam-Bates Deniz Özkundakci David P. Hamilton 《新西兰海洋与淡水研究杂志》2020,54(4):636-657
ABSTRACT Knowledge of trophic status is fundamental to understanding the condition and function of lake ecosystems. We developed regression models to predict chlorophyll a concentrations (chl a) in New Zealand lakes for reference and current states, based on an existing dataset of total nitrogen (TN) and total phosphorus (TP) concentrations for 1031 lakes. Models were then developed to predict Secchi depth based on chl a and a sediment resuspension term applicable to shallow lakes. Estimates of all four Trophic Level Index (TLI) variables (chl a, TN, TP and Secchi depth) were analysed to estimate reference and current state TLI for the nationally representative sample of 1031 lakes. There was a trend of eutrophication between reference and current states, with systematic differences among lake geomorphic types. Mean chl a increased 3.5-fold (2.42?mg?m?3 vs. 8.32?mg?m?3) and mean Secchi depth decreased (indicating lower clarity) by approximately one-third (9.62?m vs. 6.48?m) between reference and current states. On average, TLI increased by 0.67, with the TLI increase >1 in approximately one-third (31%) of lakes. This study informs the status of lake ecosystems in NZ and provides benchmarks to guide management and assessment. 相似文献
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Akin Idil Deniz Garnica Sophia S. Robichaud Peter R. Brown Robert E. 《Geotechnical and Geological Engineering》2022,40(3):1187-1200
Geotechnical and Geological Engineering - Post-wildfire erosion and the slope instability issues associated with it are a global problem that can negatively affect transportation corridors, the... 相似文献
24.
In the present research, laundry wastewater treatment is studied using the electrocoagulation/electroflotation process. For the optimization of treatment conditions such as electrode type (Al–Al, Al–Fe, Fe–Fe, and Fe–Al), initial pH (5–9), current (0.54–2.16 A), and application time (15–60 min), response surface methodology is used. Removal efficiencies of chemical oxygen demand (COD), color, anionic surfactant, microplastic, and phosphate are studied. It is determined that the most effective removal is obtained with 2.16 A current, pH 9, and 60 min reaction time using Fe–Al electrode. Here, 91%, 94%, 100%, and 98% removal efficiencies are achieved for COD, surfactant, color, and microplastic, respectively. The operating cost of the combined process is calculated as $1.32 m?3 for the optimum removal parameters. The adsorption kinetics study shows that the removal follows second‐order kinetics. The laboratory‐scale test results indicate that the electrocoagulation/electroflotation process is feasible for the treatment of laundry wastewater. 相似文献
25.
This study aims to demonstrate the potential of a process-based regional ecosystem model, LPJ-GUESS, driven by climate scenarios generated by a regional climate model system (RCM) to generate predictions useful for assessing effects of climatic and CO2 change on the key ecosystem services of carbon uptake and storage. Scenarios compatible with the A2 and B2 greenhouse gas emission scenarios of the Special Report on Emission Scenarios (SRES) and with boundary conditions from two general circulation models (GCMs) – HadAM3H and ECHAM4/OPYC3 – were used in simulations to explore changes in tree species distributions, vegetation structure, productivity and ecosystem carbon stocks for the late 21st Century, thus accommodating a proportion of the GCM-based and emissions-based uncertainty in future climate development. The simulations represented in this study were of the potential natural vegetation ignoring direct anthropogenic effects. Results suggest that shifts in climatic zones may lead to changes in species distribution and community composition among seven major tree species of natural Swedish forests. All four climate scenarios were associated with an extension of the boreal forest treeline with respect to altitude and latitude. In the boreal and boreo-nemoral zones, the dominance of Norway spruce and to a lesser extent Scots pine was reduced in favour of deciduous broadleaved tree species. The model also predicted substantial increases in vegetation net primary productivity (NPP), especially in central Sweden. Expansion of forest cover and increased local biomass enhanced the net carbon sink over central and northern Sweden, despite increased carbon release through decomposition processes in the soil. In southern Sweden, reduced growing season soil moisture levels counterbalanced the positive effects of a longer growing season and increased carbon supply on NPP, with the result that many areas were converted from a sink to a source of carbon by the late 21st century. The economy-oriented A2 emission scenario would lead to higher NPP and stronger carbon sinks according to the simulations than the environment-oriented B2 scenario. 相似文献
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H. S. B. Duzgun M. S. Yucemen H. S. Kalaycioglu K. Celik S. Kemec K. Ertugay A. Deniz 《Natural Hazards》2011,59(2):917-947
In this paper, an integrated urban earthquake vulnerability assessment framework, which considers vulnerability of urban environment
in a holistic manner and performs the vulnerability assessment for the neighborhood scale, is proposed. The main motivation
behind this approach is the inability to implement existing vulnerability assessment methodologies for countries like Turkey,
where the required data are usually missing or inadequate for the decision-makers in prioritization their limited resources
for risk reduction in the administrative units from which they are responsible for. The methodology integrates socio-economical,
structural, coastal, ground condition, vulnerabilities (fragilities), as well as accessibility to critical services. The proposed
methodology is implemented for Eskisehir, which is one of the metropolitans of Turkey. In the implementation of the proposed
framework, geographic information system (GIS) is used. While the overall vulnerabilities obtained for neighborhoods are mapped
in GIS, the overall vulnerabilities obtained for buildings are visualized in 3D city model. The main reason behind using different
mapping and visualization tools for vulnerabilities is to provide better ways for communicating with decision-makers. The
implementation of the proposed vulnerability assessment methodology indicates that an urban area may have different vulnerability
patterns in terms of structural, socio-economical, and accessibility to critical services. When such patterns are investigated,
effective vulnerability reduction policies can be designed by the decision-makers. The proposed methodology well serves for
this purpose. 相似文献
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This paper attempts to present and discuss the geomorphological and spatial analyses of Hygassos in the middle Mediterranean (a demos in ancient Bozburun Peninsula) through the application of GIS and photogrammetry, where necessary. The contextual data is composed of the settlement features and humanly constructed terrace relics. In search of the spatial and social territoria, the research questions greatly lean on the present geographical attributes and, the results of a recent survey concerning the ruins situated along a narrow valley in modern Selimiye-K?z?lköy and the Acropolis rising beside. The physical scope encompasses the khora of the Acropolis whose spatial coverage applies to ca. 27.26 km2. As the results show, the socio-economic transformation of Hygassos, under the observance of a major stronghold (Kaletepe), must have been quite dependent on the interplay of the topographical and natural factors, as well as the likely shifts from or to the Acropolis over time. However, ambiguities remain for the resilient western half territory (near immediate Losta Bay) which perhaps encroaches on the frontiers of neighbouring Tymnos. Unfavourable but cultivable areas were preferably used for household construction and terracing whereas the land exposed to maximum erosion was refrained for settling purposes. 相似文献
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Deniz Karaca Tina Schleicher Christian Hensen Peter Linke Klaus Wallmann 《International Journal of Earth Sciences》2014,103(7):1817-1829
Seafloor methane emission from the Quepos Slide on the submarine segment of the Costa Rica fore-arc margin was estimated by extrapolating flux measurements from individual seeps to the total area covered by bacterial mats. This approach is based on the combination of detailed mapping to determine the abundance of seeps and the application of a numerical model to estimate the amount of benthic methane fluxes. Model results suggest that the majority of the studied seeps transport rather limited amount of methane (on average: ~177 μmol cm?2 a?1) into the water column due to moderate upward advection, allowing for intense anaerobic oxidation of methane (AOM; on average: 53 % of the methane flux is consumed). Depth-integrated AOM rates (56–1,538 μmol CH4 cm?2 a?1) are comparable with values reported from other active seep sites. The overall amount of dissolved methane released into the water column from the entire area covered by bacterial mats on the Quepos Slide is estimated to be about 0.28 × 106 mol a?1. This conservative estimate which relies on rather accurate determinations of seafloor methane fluxes emphasizes the potential importance of submarine slides as sites of natural methane seepage; however, at present the global extent of methane seepage from submarine slides is largely unknown. 相似文献
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Yavuz Veli Lupo Anthony R. Fox Neil I. Deniz Ali 《Theoretical and Applied Climatology》2022,149(1-2):501-510
Theoretical and Applied Climatology - The short waves (less than 6000 km) embedded within the long waves and the resulting short-wave troughs have an effect on the sea-effect snow (SES).... 相似文献
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This work seeks to understand the variability of warm and cool events during summer in Turkey. Daily maximum air temperature data from 97 weather stations were analyzed to determine percentile threshold values (99th, 95th, 90th, 1st, 5th, and 10th) at each station. Trends in the percentile values were determined using the Mann–Kendall trend test. The analysis demonstrates an increase in frequency of warm, hot, and extremely hot days, whereas cool, cold, and extremely cold days show a decreasing trend. Increasing trends are statistically significant at the 0.05 and 0.01 levels for 13 and 46% of the stations, respectively. Significant decreasing trends have been detected at 0.05 and 0.01 levels for 19 and 15% of 97 stations, respectively. Analysis of the observations shows that the number of warm and hot event started to increase in the 1970s. Warm events are comparatively more numerous than cold events in western and southern parts of the country. 相似文献