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COST OF SOLID WASTE MANAGEMENT: A CASE OF BOLU
(Yildiz Technical Univ, 2011) Kose, Esra Tinmaz; Karakaya, Nusret; Aslan, R. Guler
Numerous studies concerning municipal solid waste management have been conducted in the literature, and there is a considerable accumulation of knowledge and experience about municipal solid waste management in Turkey. On the contrary, there are a few studies carried out about the cost of municipal solid waste management in Turkey. In this study, the cost of municipal solid waste management was investigated in the case of Bolu, and results were presented in the paper. The stream of municipal solid waste in the province of Bolu is periodically collected and distributed to the waste recycling center. Once papers, metals, and plastics that can be recycled are sorted out in the waste sorting center, the remaining solid waste is stored at the sanitary landfill. The cost of municipal solid waste management practice in Bolu is determined as 33,51 TL/ton waste and 56% of which value is used for worker.
Delving deeper: metabolic processes in the metalimnion of stratified lakes
(Wiley, 2017) Giling, Darren P.; Staehr, Peter Anton; Grossart, Hans Peter; Andersen, Mikkel Rene; Boehrer, Bertram; Evrendilek, Fatih; Karakaya, Nusret
Many lakes exhibit seasonal stratification, during which they develop strong thermal and chemical gradients. An expansion of depth-integrated monitoring programs has provided insight into the importance of organic carbon processing that occurs below the upper mixed layer. However, the chemical and physical drivers of metabolism and metabolic coupling remain unresolved, especially in the metalimnion. In this depth zone, sharp gradients in key resources such as light and temperature co-occur with dynamic physical conditions that influence metabolic processes directly and simultaneously hamper the accurate tracing of biological activity. We evaluated the drivers of metalimnetic metabolism and its associated uncertainty across 10 stratified lakes in Europe and North America. We hypothesized that the metalimnion would contribute highly to whole-lake functioning in clear oligotrophic lakes, and that metabolic rates would be highly variable in unstable polymictic lakes. Depth-integrated rates of gross primary production (GPP) and ecosystem respiration (ER) were modelled from diel dissolved oxygen curves using a Bayesian approach. Metabolic estimates were more uncertain below the epilimnion, but uncertainty was not consistently related to lake morphology or mixing regime. Metalimnetic rates exhibited high day-to-day variability in all trophic states, with the metalimnetic contribution to daily whole-lake GPP and ER ranging from 0% to 87% and < 1% to 92%, respectively. Nonetheless, the metalimnion of low-nutrient lakes contributed strongly to whole-lake metabolism on average, driven by a collinear combination of highlight, low surface-water phosphorous concentration and high metalimnetic volume. Consequently, a single-sensor approach does not necessarily reflect whole-ecosystem carbon dynamics in stratified lakes.
Determining lake metabolism using diel oxygen technique: a case study of Lake Abant
(Parlar Scientific Publications (P S P), 2017) Turan, Gonca Sılahan; Karakaya, Nusret
Recently, diel oxygen technique has been intensively used to estimate gross primary production (GPP), net ecosystem production (NEP), and ecosystem respiration (R) from lakes, rivers, and lagoons. This study (1) estimated GPP, NEP, and R of Lake Abant using diel oxygen technique at three locations over the period of 2012 to 2014; and (2) built empirical models to predict temporal changes in GPP, NEP, and R. To estimate the lake metabolism components, dissolved oxygen concentration (DO, mg L-1), saturated dissolved oxygen value (O-2sat, %), and water temperature (T-w, degrees C) were continuously measured using in situ water quality monitoring probes, while solar radiation (SR, W m(-2)) and wind speed (WS, m s(-1)) were monitored using a meteorological station set up by the lake. Lake Abant was found to be of a net heterotrophic character (GPP/R < 1 and NEP < 0) for 2012, 2013 and 2014. Also, temporal GPP and R dynamics were modelled and validated on a monthly basis.
Does different versus equal daytime and night-time respiration matter for quantification of lake metabolism using diel dissolved oxygen cycles?
(Cambridge Univ Press, 2011) Karakaya, Nusret
Diel dissolved oxygen (DO) measurements can be used to estimate water metabolism of aquatic systems, in particular, lakes, lagoons and streams in terms of gross primary production (GPP), ecosystem respiration (R(eco)) and net ecosystem production (NEP). One of the main assumptions in the calculation of lake metabolism is that R(eco) is the same for daytime (R(daytime)) and nighttime (R(darkhr)). This study aimed at testing the equal R(daytime) and R(darkhr) assumption to estimate GPP, R(eco) and NEP in a littoral zone of a temperate shallow lake (Lake Yenicaga) in northwestern Turkey with and without the assumption. Based on the equal R(darkhr) and R(daytime) assumption, values calculated for GPP and R(daytime) were different than those based on the different R(darkhr) and R(daytime) assumption (P<0.001). GPP was lower by 7.5% in July, 49.6% in September and 14.9% in October, while R(eco) was lower by 5.9% in July and 55.8% in September. GPP was higher by 8.9% in August and 55% in November, while R(eco) was higher by 7.8% in August and 23.9% in November.
A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins
(Nature Publishing Group, 2018) Mantzouki, Evanthia; Campbell, James; van Loon, Emiel; Visser, Petra; Konstantinou, Iosif; Karakaya, Nusret
Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.
Evaluating the impact of climate change on groundwater resources in a small Mediterranean watershed
(Elsevier, 2014) Ertürk, Ali; Ekdal, Alpaslan; Gürel, Melike; Karakaya, Nusret; Güzel, Ciğdem
Western Mediterranean Region of Turkey is subject to considerable impacts of climate change that may adversely affect the water resources. Decrease in annual precipitation and winter precipitation as well as increase in temperatures are observed since 1960s. In this study, the impact of climate change on groundwater resources in part of Koycegiz-Dalyan Watershed was evaluated. Evaluation was done by quantifying the impacts of climate change on the water budget components. Hydrological modeling was conducted with SWAT model which was calibrated and validated successfully. Climate change and land use scenarios were used to calculate the present and future climate change impacts on water budgets. According to the simulation results, almost all water budget components have decreased. SWAT was able to allocate less irrigation water because of the decrease of overall water due to the climate change. This resulted in an increase of water stressed days and temperature stressed days whereas crop yields have decreased according to the simulation results. The results indicated that lack of water is expected to be a problem in the future. In this manner, investigations on switching to more efficient irrigation methods and to crops with less water consumption are recommended as adaptation measures to climate change impacts. (C) 2014 Elsevier B.V. All rights reserved.
Gerçek Zamanlı Otomatik Göl İzleme Sistemi ile Göl Metabolizması ve Fitoplankton Biyokütlesinin Uç Olaylar ve Çevresel Değişkenlere Göre Değişiminin Araştırılması
(2018) Beklioğlu, Meryem; Karakaya, Nusret; Evrendilek, Fatih
Ocak 2015 - Ocak 2018 dönemini kapsayan üç yıllık 4 is paketinden (IP) olusan TUBITAK projesinin 1. IP si olan Eymir Gölü?nde yüksek frekanslı otomatik izleme istasyonun (YFOII) kurulması 2015 Haziran ayı itibari ile gerçeklestirilmistir. IP2 kapsamında planlanan çevrimiçi veri transferi ise ODTÜ, Limnoloji Laboratuvarında tahsis edilen bilgisayara uygun yazılımlar aracılıgı ile aktarılmıstır. IP3, YFOII?den alınan verilerin kontrolü ve takibi, manuel su kalite örneklemesi, YFOII verileri ile metabolizma hesabı, bu verilerin birincil üretim ve uç olaylarla iliskilendirilmesini kapsamaktadır. IP3 paketinden elde edilen sonuçlar ile Eymir Gölü?nün ötrofik bir göl olmasına ragmen yılın çogu zamanı heterotrofik (Net Ekosistem Üretimi (NEP) 0'dan küçük) özellikte oldugu yani atmosfere karbon salınımı yaptıgı tespit edilmistir. Fitoplankton asırı artıslarına ise genellikle Agustos ve Eylül aylarında su girisinin olmadıgı göl suyunun durgun, hava sıcaklıgının yüksek oldugu dönemlerde rastlanılmıstır. Bu dönemlerde göl metabolizmasının ototrofik (NEP 0'dan büyük) oldugu yani ekosistemin karbon tuttugu tespit edilmistir. Bu durumun uzun yıllarca yürütülen restorasyon amaçlı evsel atıksu uzaklastırılması ve biyomanipulasyonun olumlu etkisi oldugu düsünülmektedir. Bunların yanı sıra Eymir Gölü ani meteorolojik ve çevresel degisimlerden hızlıca etkilenmektedir. Özellikle rüzgar göldeki sıcaklık tabakalasmasını degistirmekte ve epilimnion tabakasında metabolizmanın salınımlar göstermesine sebep olmaktadır. Ancak bu degiskenlerin eski degerlerine dönmesi ile sistem kendini kısa sürede toparlayabilmektedir. Ayrıca yine projenin 4. IP si kapsamında, ortaokul ögrencilerinin bilimsel süreçle tanısması, doga ve göl ekolojisi bilincinin ve duyarlılıgının gelismesini amaçlayan ?Eymir Gölü Elçileri? egitim paketi gelistirilmesi hedeflenmistir. Proje kapsamında gelistirilen egitim programı ODTÜ Ankara Gelistirme Vakfı Ortaokulu ve Gölbası Cemil Yıldırım Ortaokulundan 5. ve 7. sınıf ögrencilerine uygulanmıstır. Ayrıca proje çıktıları www.lem.bio.metu.edu.tr adresinden güncel olarak paylasılmıstır. Toplanan verilerin ilgili kurumlarla paylasılması içinde site içerisinde sifre ile girilen bir sekme açılmıstır. Yine bilgiyi yayma kapsamında 9 Mart 2018 tarihinde ilgili birimlerin davet edildigi mini-çalıstay düzenlenmistir.
Global CO2 emissions from dry inland waters share common drivers across ecosystems
(Nature Research, 2020) Keller, P. S.; Catalan, N.; von Schiller, D.; Grossart, H-P; Koschorreck, M.; Obrador, B.; Frassl, M. A.; Karakaya, Nusret
Many inland waters exhibit complete or partial desiccation, or have vanished due to global change, exposing sediments to the atmosphere. Yet, data on carbon dioxide (CO2) emissions from these sediments are too scarce to upscale emissions for global estimates or to understand their fundamental drivers. Here, we present the results of a global survey covering 196 dry inland waters across diverse ecosystem types and climate zones. We show that their CO2 emissions share fundamental drivers and constitute a substantial fraction of the carbon cycled by inland waters. CO2 emissions were consistent across ecosystem types and climate zones, with local characteristics explaining much of the variability. Accounting for such emissions increases global estimates of carbon emissions from inland waters by 6% (0.12 Pg C y(-1)). Our results indicate that emissions from dry inland waters represent a significant and likely increasing component of the inland waters carbon cycle.
Göl metabolizmasının diel oksijen tekniği ile belirlenmesi: Abant gölü örneği
(2014) Karakaya, Nusret; Evrendilek, Fatih; Güngör, Kerem; Güngör, Deniz; Turan, Gonca Sılahan
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Groundwater dependent ecosystems. Part I: Hydroecological status and trends
(Elsevier Sci Ltd, 2011) Klove, Bjorn; Ala-aho, Pertti; Bertrand, Guillaume; Boukalova, Zuzana; Ertürk, Ali; Karakaya, Nusret
Groundwater dependent ecosystems (GDEs) include valuable ecosystems such as springs, wetlands, rivers, lakes and lagoons. The protection of these systems and services they provide is highlighted by international agreements, i.e. Ramsar convention on wetlands, and regional legislation, i.e. the European Water Framework Directive. Groundwater provides water, nutrients and a relatively stable temperature. However, the role of groundwater in surface ecosystems is not fully understood. The ecosystem can depend on groundwater directly or indirectly, and the reliance can be continuous, seasonal or occasional. This has implications for the vulnerability of ecosystems, as some may be easily affected by external pressure. Conceptual models and quantitative assessments of how groundwater interacts with the environment are needed. GDEs are also threatened by different land use activities and climate change. Hence, we need to understand how GDEs are affected by changes in groundwater quantity and quality, as severe groundwater changes have been observed in many regions. This study examines key aspects of GDEs (hydrogeology, geochemistry and biodiversity) in order to improve conceptual understanding of the role of groundwater in such ecosystems. The status and baseline of different types of GDEs are discussed, with particular emphasis on past evidence of environmental change and potential thresholds and threats in GDEs in various parts of Europe with different land use, climate and geology. (C) 2011 Elsevier Ltd. All rights reserved.
Groundwater dependent ecosystems. Part II. Ecosystem services and management in Europe under risk of climate change and land use intensification
(Elsevier Sci Ltd, 2011) Klove, Bjorn; Allan, Andrew; Bertrand, Guillaume; Druzynska, Elzbieta; Ertürk, Ali; Karakaya, Nusret
Groundwater in sufficient amounts and of suitable quality is essential for potable water supplies, crop irrigation and healthy habitats for plant and animal biocenoses. The groundwater resource is currently under severe pressure from land use and pollution and there is evidence of dramatic changes in aquifer resources in Europe and elsewhere, despite numerous policy measures on sustainable use and protection of groundwater. Little is known about how such changes affect groundwater dependent ecosystems (GDEs), which include various aquatic and terrestrial ecosystems above ground and inside the aquifer. Future management must take this uncertainty into account. This paper focuses on multiple aspects of groundwater science, policy and sustainable management. Examples of current management methods and practices are presented for selected aquifers in Europe and an assessment is made of the effectiveness of existing policies such as the European Water Framework Directive and the Habitat Directive in practice and of how groundwaters and GDEs are managed in various conditions. The paper highlights a number of issues that should be considered in an integrated and holistic approach to future management of groundwater and its dependent ecosystems. (C) 2011 Elsevier Ltd. All rights reserved.
Historical spatiotemporal analysis of land-use/land-cover changes and carbon budget in a temperate peatland (Turkey) using remotely sensed data
(Elsevier Sci Ltd, 2011) Evrendilek, Fatih; Berberoğlu, Süha; Karakaya, Nusret; Çilek, Ahmet; Aslan, Güler; Güngör, Kerem
Rate and amount of carbon (C) storage in peatlands play a vital role in global biogeochemical cycles despite their globally small spatial extent. Carbon dioxide (CO(2)) emissions from drained peatlands is a function of drainage intensity and extent of peatlands, peat thickness, land use and land cover (LULC) type to which peatlands are converted, and management practices. Historical LULC change-detection of Yenicaga peatlands and wet flats yielded an estimated conservative decrease in C pool from 2.43 +/- 0.15 million metric tons (Mt) in 1944 to 0.65 +/- 0.04 Mt in 2009 due mostly to drainage by agricultural and afforestation activities. Drainage-induced C emission rate was estimated to range from 12.5 to 32.5 t C ha(-1) yr(-1). Our extrapolation of the C emission rate to the entire peatland area of 240 km(2) in Turkey resulted in CO(2) emissions of 0.30-0.78 Mt in 2009, equivalent to 0.01%-0.02% of the global LULC-related CO(2) emissions of 3230 Mt in 2009. (C) 2011 Elsevier Ltd. All rights reserved.
Implementation of DRASTIC method on a coastal lagoon watershed for planning purposes
(Taylor and Francis - Balkema, 2014) Ekdal, Alpaslan; Gürel, Melike; Ertürk, Ali Esra Bölükbaşı; Karakaya, Nusret; Gönenç, I. Ethem
Municipal wastewaters in Finland are treated with processes that efficiently remove phosphorus and organic matter. Traditionally, nitrogen removal has been considered less important because of the inconsiderable role of nitrogen in primary production especially in the inland waters. Cold temperature of wastewaters also impedes nitrogen removal and makes enhanced nitrogen removal challenging and expensive in Finland. Bothnian Bay, the northern part of the Baltic Sea is known to be phosphorus limited, whereas southern parts of the Baltic Sea are more nitrogen limited. In coastal waters nutrient limitation varies.
Integrating ATR-FTIR and data-driven models to predict total soil carbon and nitrogen towards sustainable watershed management
(Dr Jyoti Garg, 2013) Aslan-Sungur, Güler; Evrendilek, Fatih; Karakaya, Nusret; Güngör, Kerem; Kılıç, Sinan
The use of Attenuated Total Reflectance (ATR) is an alternative method in determining carbon (C), nitrogen (N) and other elemental contents of organic and inorganic soils for which diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy has been mostly utilized. In this study, the combined use of ATR-Fourier transform infrared (FTIR) spectroscopy and partial least square regression (PLSR) or artificial neural network (ANN) models in estimating total soil C and N have been explored which provide direct, rapid, economical and multiple in situ measurements. Total soil C and N data obtained from 153 soil samples across agricultural lands and analyzed using CNH elemental analyzer were used to build PLSR and ANN models as a function of ATR-FTIR spectrum ranges based on a training dataset with leave-one-out cross validation (LCV) and independent validation (IV) dataset that randomly constitute 67% and 33% of the entire dataset respectively. Wavenumber ranges of 650-2365 cm(-1) and 773-1726 cm(-1) in ATR-FTIR data were selected as predictors for PLSR and ANN models of soil C respectively. PLSR model of soil C led to r(2) = 0.86 for training and r(2) = 0.68 for validation, with PLSR model of soil N as a result of wavenumber range of 1300-1400 cm(-1) leading to r(2) = 0.81 for training and r(2) < 0.1 for validation. Multilayer perceptron model appeared to be the best-performing ANN for the emulations of both total soil C and N and outperformed PLSR model of total soil N.
Interaction effects of the main drivers of global climate change on spatiotemporal dynamics of high altitude ecosystem behaviors: process-based modeling
(Springer, 2020) Yıldız, Kadir; Karakaya, Nusret; Kılıç, Şeref; Evrendilek, Fatih
Soil organic carbon and nitrogen (SOC-N) dynamics are indicative of the human-induced disturbances of the terrestrial ecosystems the quantification of which provides insights into interactions among drivers, pressures, states, impacts, and responses in a changing environment. In this study, a process-based model was developed to simulate the eight monthly outputs of net primary productivity (NPP), SOC-N pools, soil C:N ratio, soil respiration, total N emission, and sediment C-N transport effluxes for cropland, grassland, and forest on a hectare basis. The interaction effect of the climate change drivers of aridity, CO(2)fertilization, land-use and land-cover change, and best management practices was simulated on high altitude ecosystems from 2018 to 2070. The best management practices were developed into a spatiotemporally composite index based on SOC-N stock saturation, 4/1000 initiative, and RUCLE-C factor. Our model predictions differed from the remotely sensed data in the range of - 64% (underestimation) for the cropland NPP to 142% (overestimation) for the grassland SOC pool as well as from the global mean values in the range of - 97% for the sediment C and N effluxes to 60% for the total N emission from the grassland. The interaction exerted the greatest negative impact on the monthly sediment N efflux, total N emission, and soil respiration from forest by - 90.5, - 82.7, and - 80.3% and the greatest positive impact on the monthly sediment C effluxes from cropland, grassland, and forest by 139.3, 137.1, and 133.3%, respectively, relative to the currently prevailing conditions.
Juxtaposing the spatiotemporal drivers of sediment CO2, CH4, and N2O effluxes along ecoregional, wet-dry, and diurnal gradients
(Turkish National Committee For Air Pollution And Control (TUNCAP), 2021) Arı, Pelin Ertürk; Karakaya, Nusret; Evrendilek, Fatih
Globally, lakes are facing greater drying rates than before the industrial revolution due to global climate change, water withdrawals, and land use and land cover changes. Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes of the lakeshore sediments still remain poorly represented and understood, with important implications for the global carbon (C) and nitrogen (N) budget closures. This study quantifies spatiotemporal dynamics and (non-)linear drivers of CO2, CH4, and N2O effluxes from sediments of 20 lakes along wet-dry lakeshore, diurnal, and ecoregional gradients in the western part of Turkey. Mean daily CO2, CH4, and N2O effluxes were estimated at 98.64 ± 386.47, 1.42 ± 1.71, and 0.12 ± 0.24 from wet sediments and at 393.60 ± 386.94, 0.82 ± 1.58, and 0.24 ± 0.22 from dry sediments, with an overall mean of 242.28 ± 404.1, 1.09 ± 1.53, and 0.18 ± 0.23 mmol m−2 d−1, respectively. The variability in the GHG effluxes was most sensitive to the interaction between latitude and wet-dry location. Out of 14 significant environmental drivers, the most important ones that minimized and maximized CO2, CH4, and N2O effluxes were PO4–P content, three-summer month standardized precipitation index, and redox potential, respectively, based on a random forest-based optimization.
Juxtaposing the spatiotemporal drivers of sediment CO2, CH4, and N2O effluxes along ecoregional, wet-dry, and diurnal gradients
(Elsevier B.V., 2021) Ertürk Arı, Pelin; Karakaya, Nusret; Evrendilek, Fatih
Globally, lakes are facing greater drying rates than before the industrial revolution due to global climate change, water withdrawals, and land use and land cover changes. Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes of the lakeshore sediments still remain poorly represented and understood, with important implications for the global carbon (C) and nitrogen (N) budget closures. This study quantifies spatiotemporal dynamics and (non-)linear drivers of CO2, CH4, and N2O effluxes from sediments of 20 lakes along wet-dry lakeshore, diurnal, and ecoregional gradients in the western part of Turkey. Mean daily CO2, CH4, and N2O effluxes were estimated at 98.64 ± 386.47, 1.42 ± 1.71, and 0.12 ± 0.24 from wet sediments and at 393.60 ± 386.94, 0.82 ± 1.58, and 0.24 ± 0.22 from dry sediments, with an overall mean of 242.28 ± 404.1, 1.09 ± 1.53, and 0.18 ± 0.23 mmol m?2 d?1, respectively. The variability in the GHG effluxes was most sensitive to the interaction between latitude and wet-dry location. Out of 14 significant environmental drivers, the most important ones that minimized and maximized CO2, CH4, and N2O effluxes were PO4–P content, three-summer month standardized precipitation index, and redox potential, respectively, based on a random forest-based optimization. © 2021 Turkish National Committee for Air Pollution Research and Control
Large interannual variability in net ecosystem carbon dioxide exchange of a disturbed temperate peatland
(Elsevier, 2016) Aslan-Sungur, Güler; Lee, Xuhui; Evrendilek, Fatih; Karakaya, Nusret
Peatland ecosystems play an important role in the global carbon (C) cycle as significant C sinks. However, human-induced disturbances can turn these sinks into sources of atmospheric CO2. Long-term measurements are needed to understand seasonal and interannual variability of net ecosystem CO2 exchange (NEE) and effects of hydrological conditions and their disturbances on C fluxes. Continuous eddy-covariance measurements of NEE were conducted between August 2010 and April 2014 at Yenicaga temperate peatland (Turkey), which was drained for agricultural usage and for peat mining until 2009. Annual NEE during the three full years of measurement indicated that the peatland acted as a CO2 source with large interannual variability, at rates of 246, 244 and 663 g Cm-2 yr(-1) for 2011, 2012, and 2013 respectively, except for June 2011, and May to July 2012. The emission strengths were comparable to those found for severely disturbed tropical peatlands. The peak CO2 emissions occurred in the dry summer of 2013 when water table level (WTL) was below a threshold value of -60 cm and soil water content (SCW) below a threshold value of 70% by volume. Water availability index was found to have a stronger explanatory power for variations in monthly ecosystem respiration (ER) than the traditional water status indicators (SCW and WTL). Air temperature, evapotranspiration and vapor pressure deficient were the most significant variables strongly correlated with NEE and its component fluxes of gross primary production and ER. (C) 2016 Elsevier B.V. All rights reserved.
Model-based assessment of groundwater vulnerability for the Dalyan Region of southwestern Mediterranean Turkey
(Springer Heidelberg, 2017) Ertürk, Ali; Ekdal, Alpaslan; Gürel, Melike; Karakaya, Nusret; Cüceloğlu, Gökhan
The Dalyan Region that drains into a complex lagoon system is located on the Mediterranean Sea coast of southwest Turkey. There are no large streams in the area, indicating that a considerable amount of freshwater draining into the lagoon is expected to be based on groundwater inflows and that groundwater quality is an important issue for the lagoon ecosystem. Since the lagoon and its watershed are within an environmental special protection area, planning preventive and mitigative measures toward water quantity and quality, including groundwater, is crucial. Since an important step in such a study is the generation of vulnerability map of groundwater pollution, this study aims at the generation of an intrinsic groundwater vulnerability map and its assessment for the first time in the study area based on the DRASTIC method. Since the DRASTIC method requires recharge rates for the calculation of groundwater pollution potential index, these were obtained from a previous modeling study conducted in the same area, where SWAT model was used. The intrinsic vulnerability maps generated were overlaid with current land-use maps to evaluate actual groundwater pollution risk. Our analyses showed that 46% of the study area is under the high risk of groundwater pollution, where 62% of the vulnerable high-risk area is agricultural land.
Modeling and validating long-term dynamics of diel dissolved oxygen with particular reference to pH in a temperate shallow lake (Turkey)
(Wiley-Blackwell, 2011) Karakaya, Nusret; Evrendilek, Fatih; Güngör, Kerem
Long-term monitoring of changes in dissolved oxygen (DO) and pH is of great importance to quantifying aquatic ecosystem metabolism, particularly for lakes under the changing global environment. During 173 days, diel DO cycles were measured in situ along with the main driving variables of pH, wind speed (WS), and net solar radiation (Rn) in a temperate shallow lake. Best-fit multiple non-linear regression (MNLR) models of diel DO time series were built and validated on a monthly basis, with R(2) values ranging from 42.4% in September to 95.4% in November for validation. The strong relationship between diel DO and pH (r = 0.6) appeared to be related to the patterns of ecosystem productivity and respiration, and sensitivity of decomposing bacteria to changes in pH. pH-driven lake metabolism appears to have significant implications for diel and seasonal lake metabolism in a changing global environment.

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