Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2025Scopus SJRQ3/r/munzur/1211
  Oxidative and Antioxidant Responses in Daphnia magna Following Exposure to Sub-Lethal Glyphosate Concentrations

  Sahilli, Yeliz Çakir; Korkmaz, Volkan

  Abstract: Glyphosate (GLY) is one of the most widely used herbicides in modern intensive agriculture to enhance crop production. However, the chemical additives in commercial formulations and the active ingredient itself can adversely affect biological and chemical processes in aquatic organisms. Therefore, the aim of this study was to evaluate the effects of sub-lethal concentrations of GLY (0, 0.23, 0.58, and 1.17 μg/L) on oxidative stress biomarkers—namely lipid peroxidation (measured as malondialdehyde, MDA), and antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and reduced glutathione, GSH)—in Daphnia magna after 24 and 96 h of exposure. The results showed that SOD activity increased in all treatment groups compared to the control at both time points while CAT activity decreased in all groups. GSH and TBARS (thiobarbituric acid reactive substances) levels were significantly elevated after 24 and 96 h in all exposed groups. Overall, D. magna was sensitive to sub-lethal concentrations of GLY, and changes in SOD and CAT activities, as well as GSH and TBARS levels, these biomarkers can serve as useful indicators for detecting glyphosate-induced oxidative stress and water pollution.

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  AtıfOpenAlex1

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• MakaleAçık Erişim2024/r/munzur/6304
  Effect of Synthetic Wastewater on Antioxidant Defence System in Dreissena polymorpha

  Serdar, Osman; Erguven, Gokhan Onder; Yildirim, Nuran Cikcikoglu; Korkmaz, Volkan; Erguven, Gozde

  The effects of the synthetic wastewater on antioxidant defence system in Dreissena polymorpha was evaluated. For this purpose, SOD, CAT, GPX activities and TBARS and GSH levels in tissues were determined by using commercial kits. The activities of SOD and CAT were in sythtetic group were determined lower than the control group in D. polymorpha during 24 and 96 h (p<0.05). After exposure of the cells of D. polymorpha samples to synthetic wastewater, depletion in GSH levels and subsequent increase in TBARS levels were observed, reflecting their unstable state. According to the data obtained from the study, It can be inferred that the biomarkers being domestic monitored are beneficial and effective in evaluating the biochemical mechanisms of wastewater as early warning indicators.

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• MakaleAçık Erişim2023Scopus SJRQ3/r/munzur/1622
  The biosorption of Co(II) by Homalothecium sericeum from aqueous solutions under batch conditions: response surface methodology optimization and Daphnia magna bioassay

  Tanyol, Mehtap; Korkmaz, Volkan; Yildirim, Numan; Erguven, Gokhan Onder; Ayhan, Nagihan Karaaslan; Alatas, Mevlut

  In the present work, Homalothecium sericeum biomass was used for removal of Co(II) from aqueous solution. The effects of process parameters (contact time, biosorbent amount, and initial Co(II) con-centration) on the response (Co(II) % removal) were investigated using a batch adsorption system optimized with response surface methodology/central composite design method. Under optimized conditions the maximum Co(II) removal efficiency achieved is 94.07% at an initial Co(II) concentration of 2.05 mg/L, a H. sericeum amount of 0.34 g/50 mL, and a process time of 36.09 min. In this study, the toxicity of the medium after biosorption carried out under optimized conditions was also tested with Daphnia magna bioassay. When mortality results with D. magna were evaluated, although a removal efficiency of 94.07% was obtained after biosorption, this was not sufficient to reduce mortality of D. magna.

  AtıfScopus1·WoS2

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• MakaleAçık Erişim2022Scopus SJRQ3/r/munzur/3048
  Decolorization of Remazol Brilliant Violet 5R and Brilliant Green dyes by Hypnum cupressiforme using response surface methodology-central composite design methodology: toxicity assessment studies by Daphnia magna

  Korkmaz, Volkan; Erguven, Gokhan Onder; Tanyol, Mehtap; Alatas, Mevlut; Yildirim, Numan

  This study is the first report that aims to optimize the removal of Remazol Brilliant Violet 5R (RBV 5R) and Brilliant Green (BG) from synthetic solutions using Hypnum cupressiforme samples from Abant Mountains of Bolu (Turkey) as biosorbent and to conduct toxicity evaluation studies of treated wastewater using Daphnia magna. Optimization was performed using central composite design under response surface methodology with the operational factors of dye concentration, H. cupressiforme dose, and process time. The optimal conditions for dye concentration, H. cupres-siforme dose, and process time obtained by the numerical analysis were 19.02 mg/L, 0.18 g/50 mL and 110.59 min for RBV 5R, while these values were 18.57 mg/L, 0.18 g/50 mL and 99.45 min for BG, respectively. At the optimum values, maximum RBV 5R and BG removal were achieved as 99.39% and 99.22%, respectively. The D. magna mortality rates showed that treatment with adsorption were sufficient to remove the complete toxicity of dyes especially for RBV 5R.

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  AtıfScopus2·WoS2·OpenAlex2

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• MakaleAçık Erişim2021/r/munzur/6642
  The Effect of Gadolinium and Lanthanum on the Mortality ofDaphnia magna

  Korkmaz, Volkan; Ergüven, Gökhan Önder; Yildirim, Numan; Cıkcıoğlu Yıldırım, Nuran

  Rare earth elements (REEs) have been recently identified as emergent contaminants because of their numerous and increasingapplications in technology. The impact of REEs on downstream ecosystems, notably aquatic organisms, is of particular concern, but has to date been largely overlooked. The purpose of this study were to generate toxicological information regarding thesepoorly studied Gadolinium and Lanthanum elements to determine the current risk associated with these elements. The results of this work indicate notable D. magna mortality in high concentration of La and Gd. The highest mortality rate was determined as100% at 100 mg/L concentration for both La and Gd at the end of the 24hour . At the end of the 48 hours, the highest mortalityrate for both La and Gd was observed at 100 mg/L concentration. No mortality was determined at 48 hours at a concentration of10 mg/l Gd. 100% mortality was observed for two elements at 50 and 100 mg/L concentrations at 72 hours. in the natural living water no death was seen in this time period. The findings from our study also indicate that Gd is more toxic than La. Due to thismortality effect of La and Gd to D. magna, it will be important for the ensuring continuity of the ecosystem to monitor especiallyaquatic environments and to treat them with appropriate treatment methods from contaminated environments.

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  AtıfOpenAlex2

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• MakaleAçık Erişim2021Scopus SJRQ1/r/munzur/2675
  The bioremediation of glyphosate in soil media by some newly isolated bacteria: The COD, TOC removal efficiency and mortality assessment for Daphnia magna

  Korkmaz, Volkan; Yildirim, Numan; Erguven, Gokhan Onder; Durmus, Barbaros; Nuhoglu, Yasar

  In this study, the bioremediation capacity of three isolates of Bacillus aryabhattai, Pseudomonas azotoformans and Sphingomonas pseudosanguinis and their consortia at glyphosate added soil medium investigated via the reduction of chemical oxygen demand (COD) and total organic carbon (TOC) parameters in filtrate waters obtained from a designed bioremediation setup. Additionally, mortality assays were performed on the filtrate waters with model organism Daphnia magna. According to the results of the experiments, at the end of the 11 days, the highest COD reduction rate seen in media with S. pseudosanguinis as 92.1% while TOC rate was 69.13% in consortia media. While the mortality rate was 10, 10 and 5% on B, P and S application groups at the end of the 72th respectively, these rates were 100% in control group at the end of the 48th. According to the results obtained from bioremediation and mortality assessment, these bacteria can reach the high bioremediation rate one by one and in consortia media.

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  AtıfScopus14·OpenAlex16

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• MakaleYalnız künye2020/r/munzur/3193
  A RESEARCH FOR BACTERIAL SELF-HEALING IN METAKAOLIN BASED GEOPOLYMER MORTARS

  Yilmazer Polat, Berivan; Uysal, Mucteba; Korkmaz, Volkan

  Cement production is a polluting process for nature. For this reason, new types of concrete which can be produced with recycled materials and without cement continue to be investigated. On the other hand; cracks in structural elements reduce the strength and durability of a building. Extending service life of buildings has eliminated the cost of rebuilding and thus, contributed to both the economy and the ecosystem. Due to this, research on crack healing in Portland cement concretes with various bacteria is continuing for some time. However, there are not enough studies in literature regarding the improvement of metakaolin-based geopolymer mortars produced without using cement by urolytic bacteria. The parameters of temperature, pH and void ratio of bacterial geopolymer mortar affect the viability of bacteria. For example, pH value of the medium required for the survival of bacteria is, generally around nine. During the production of geopolymer concrete, a sudden increase in high alkali environment occurs due to use of activators. This reduces the survival rate of bacteria added to the mixture during the production of geopolymer mortar. In this study, the most suitable environment for geopolymer mortar, and the conditions for the bacteria to survive until the end of the curing process for the mortar to be strengthened were investigated. Analyses on the effects of urolytic bacteria and geopolymer mortar healing process on mechanical strength of the mortar were conducted. Sporosarcina Pasteurii were used for the self healing process. Various mixtures of geopolymer mortars were cured under different environmental conditions to observe changes in their mechanical strength and water absorption capacity. As the result of the study, the most suitable mixture ratio and curing medium were identified. It was observed that the nutrient, ensuring the life cycle of the urolytic bacteria, had no negative effect on the mechanical strength of mortar and reduced capillary water absorption of the mortar. This study is a specific text in the literature that analyzes bacterial curing conditions and the effect of improving geopolymer mortar.

  AtıfScopus14

  İncele
• MakaleYalnız künye2018Scopus SJRQ1/r/munzur/3577
  Comparative evaluation of toxicological effects and recovery patterns in zebrafish (Danio rerio) after exposure to phosalone-based and cypermethrin-based pesticides

  Korkmaz, Volkan; Güngördü, Abbas; Ozmen, Murat

  This study evaluated the toxic effects and recovery patterns in zebrafish (Danio rerio) after exposure to phosalone-based (PBP) and cypermethrin-based (CBP) pesticides. Initially, the 96 h LC50 values of the pesticides were calculated as being 5.35 µg of active ingredient (AI) L−1 for CBP and 217 µg AI L−1 for PBP based on measured concentrations. Accordingly, experimental groups were exposed to three sublethal concentrations of pesticides for 96 h, separately, and then zebrafish were transferred to pesticide-free conditions for 10 and 20 days recovery periods. Biochemical markers were assessed including carboxylesterase (CaE), acetylcholinesterase (AChE), glutathione S-transferase (GST), lactate dehydrogenase, glutathione peroxidase, catalase, alanine and aspartate aminotransferase (ALT, AST) activities after the exposure and recovery periods. Also, the pesticide concentrations in test water were quantified by high-performance liquid chromatography (HPLC) analysis. Our results showed that AChE and CaE activities were significantly inhibited and GST was induced by both pesticides after 96 h exposure. For PBP exposure, the decreases for GST induction and CaE inhibition showed a partial recovery in pesticide-free conditions. However, the decreases in AChE activity for CBP exposure and insufficient increases in same enzyme activity for PBP exposure after 20 days in pesticide-free conditions indicated that the projected recovery period was not enough to the recovery of AChE activities and for the improvement of fish health.

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  AtıfScopus56·WoS50·OpenAlex59

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