Reference and current Trophic Level Index of New Zealand lakes: benchmarks to inform lake management and assessment     

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   

Evidence of extensive carbonate mounds and sublacustrine channels in shallow waters of Lake Van,eastern Turkey,based on high-resolution chirp subbottom profiler and multibeam echosounder data     

Deniz Cukur  Sebastian Krastel  M. Namık Çağatay  Emre Damcı  Aysegül Feray Meydan  Seong-Pil Kim 《Geo-Marine Letters》2015,35(5):329-340

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Spatiotemporal meteorological drought assessment: a case study in south-east Australia     

Yildirim  Gokhan  Rahman  Ataur 《Natural Hazards》2022,111(1):305-332

Natural Hazards - An understanding on different aspects of droughts is crucial for effective water resources management. Australia has experienced notable droughts in recent years. The present...  相似文献   

Homogeneity and trend analysis of rainfall and droughts over Southeast Australia     

Yildirim  Gokhan  Rahman  Ataur 《Natural Hazards》2022,112(2):1657-1683

Natural Hazards - This study investigates rainfall and drought characteristics in southeastern Australia (New South Wales and Victoria) using data from 45 rainfall stations. Four homogeneity tests...  相似文献   

Surficial Stabilization of Wildfire-Burnt Hillslopes Using Xanthan Gum and Polyacrylamide     

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   

Electrocoagulation/Electroflotation Process for Removal of Organics and Microplastics in Laundry Wastewater     

Ceyhun Akarsu  Fatma Deniz 《洁净——土壤、空气、水》2021,49(1)

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   

Structural and Geomorphological Aspects of the Kat Landslides (Tokat—Turkey) and Susceptibility Mapping by Means of GIS     

Işik Yilmaz  Mustafa Yildirim 《Environmental Geology》2006,50(6):931-931

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Modelling Regional Climate Change Effects On Potential Natural Ecosystems in Sweden   总被引：9，自引：0，他引：9  

Deniz Koca  Benjamin Smith  Martin T. Sykes 《Climatic change》2006,78(2-4):381-406

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   

Age and petrogenesis of plagiogranite intrusions in the Ankara mélange, central Turkey     

Yildirim  Dilek  Peter  Thy 《Island Arc》2006,15(1):44-57

Abstract   The Ankara mélange within the Izmir–Ankara–Erzincan suture zone in north-central Turkey includes ophiolitic fragments that represent the remnants of an oceanic basement evolved between the Sakarya and Kirsehir continental blocks in the early Mesozoic. The serpentinized upper mantle peridotites and lower crustal rocks in these ophiolites are cross-cut by dolerite and plagiogranite dykes, which show mutually intrusive relations indicating their synchronous emplacement into the pre-existing oceanic lithosphere. Zircon dating (U–Pb) of a plagiogranite dyke has revealed a concordia age of ∼179 ± 15 Ma that is interpreted here as the crystallization age of this differentiated rock. A fourth fraction of the zircon separates from this rock has also shown an inherited component greater than 1.7 Ga, possibly derived from the Precambrian core of the Rhodope–Strandja Metamorphic Massif in the Balkan Peninsula. Models for plagiogranite formation were tested and it is concluded that a high extent (<70%) of anhydrous or water-undersaturated, early amphibole-free fractionation of a basaltic melt source may have readily produced the observed REE concentrations for the Ankara mélange plagiogranites. The trace element abundances and other geochemical features of the coeval dolerite dykes are similar to those of the plagiogranites, suggesting a common melt source. The Ta–Nb patterns shown by both the plagiogranite and dolerite dykes are typical of arc-related petrogenesis and can be explained by the addition of slab-derived components to a depleted mantle wedge. The Early Jurassic ophiolitic basement and the dyke intrusions were formed in a back-arc setting between the Paleo- and Neo-Tethyan domains in the eastern Mediterranean region. The Izmir–Ankara–Erzincan Sea developed in this back-arc environment and the related suture zone had a diachronous evolutionary history.  相似文献   

Air mass modification over Lake Michigan     

Wen-Yih Sun  Ahmet Yildirim 《Boundary-Layer Meteorology》1989,48(4):345-360

The modification of a relatively cold air mass over the warm water of Lake Michigan is studied by using a two-dimensional nonlinear mesoscale model. Considerable amounts of heat and water vapor are supplied from the water surface to the lower atmosphere by turbulent eddies. A convective mixed layer develops and grows toward the downwind region with stratocumulus clouds over the lake.The model simulates the warming and moistening of the mixed layer, the development of a boundary layer, the divergence and convergence of wind near the coastlines, and the turbulent fluxes.The model warming of the mixed layer across the lake was about 2.2 °K and the moistening of the mixed layer was about 0.8 g kg^–1, which are comparable to 2.7 °K and 0.8 g kg^–1 observed by Lenschow (1973). The convective boundary layer, which includes the cloud layer, subcloud layer, and superadiabatic layer near the water surface, is well simulated. The tilt of the inversion which coincides with the cloud top is also well reproduced. When a prescribed cooling rate is applied at the cloud top, stronger turbulence and a deeper cloud layer are generated. Without the cooling, the cloud is shallow and the shape of the cloud base is determined by surface conditions. The rise of the inversion is due to upward vertical motion, and deepening of the convective layer in the downwind region.  相似文献