Given that Turkey has recently committed itself for the first time to reducing its CO₂ emissions in the interest of sustainable growth in not only Turkey but also the world as a whole, this paper examines the relationship between energy consumption, CO₂ emissions, and economic growth in Turkey for the period 1960–2014. In view of the different findings concerning causality and the character of the relationships between these variables revealed in our review of past studies (in most cases using quite different methods), this paper utilizes several different but related methodological approaches for identifying causal relationships. These include both the Toda and Yamamoto (1995) approach, the Fourier Toda-Yamamoto for Cumulative Frequency approach developed by Nazlioglu et al. (2016), vector error correction model (VECM) methodology, and the asymmetric Granger causality test proposed by Hatemi-J (Empir Econ 43:447–456, Hatemi-j 2012). Our results show that, when we apply the popular Toda-Yamamoto model, causality in these relationships is not confirmed even among any of the relevant variables in Turkey. Yet, when the Fourier Toda-Yamamoto tests for cumulative frequency are employed, we find unidirectional causality running from GDP per capita to emissions of CO₂ per capita. Moreover, when we utilize the VECM methodology, the results show that long-run causality exists from GDP per capita and energy to CO₂ emissions. When we apply the asymmetric causality tests, the results provide even stronger evidence for a unidirectional causal relationship from GDP per capita to CO₂ emissions. As a result, the latter sets of results, based on more realistic conditions, suggest very strongly that, if Turkey is to meet the objectives of its ambitious Climate Change Action Plan commitment to the United Nations to reduce its CO₂ per capita emissions relative to its past trends by up to 21% over the coming 2021–2030 decade, it is going to get very serious about the best way to do this as soon as possible.

Microplastics (MP) are transported from land-based sources from rivers to marine waters. However, there is currently little knowledge about MP fate from land sources to marine waters. Traffic is estimated to be one of the largest sources of MP; hence, stormwater is expected to be an important transportation route of MP to marine waters. The aim of this study was to investigate the effect of the size and density of tyre wear particles in road run-off on their fate in the Göta River in Sweden using hydrodynamic modelling. The model of the stretch of Göta River, Sweden’s largest river, passing through Gothenburg (Sweden’s second largest city) and out to the sea, was set up using MIKE 3 FM software. Literature data were used to define the MP characteristics: concentrations in stormwater, prevalent particle sizes, density of MP commonly occurring in road run-off and settling velocities. Results show that higher concentrations of MP are found on the south side of the river, compared with the north side, due to higher annual average daily traffic loads along the south side of the river. The mixing processes in the river and the MP concentrations were generally influenced by the vertical water density gradient caused by saline water from the Kattegat strait. While most MP with higher density and larger size settle in the river, smaller MP with density close to 1.0 g/cm³ do not settle in the river and therefore reach the Kattegat strait and the marine environments. Further research is needed to describe the fate and transport of microplastics in the stormwater system, including treatment facilities, i.e. biofouling, aggregation, degradation and/or further fragmentation and settling.

Manganese sulfate residue (MSR) is a by-product derived from the manganese sulfate production process. In this study, an iron hydroxide adsorbent was prepared from MSR using the hydrothermal conversion method. The adsorbent was characterized and used to remove copper(II) ions from aqueous solution. Batch experiments were performed to investigate the adsorption efficiency of copper ions at different contact times, initial concentrations, solution pH levels, and reaction temperatures. Adsorption equilibrium was observed in 3 h, and the best pH was under natural conditions (pH ∼ 5.5). Increasing the initial Cu²⁺ concentration and reaction temperature can increase the adsorption quantity. The adsorption capacity of iron hydroxide at an initial concentration of 50 mg L⁻¹ was 14.515 mg g⁻¹ Cu(II) under the conditions of a nature pH and room temperature. According to the adsorption data, the pseudo-second-order model can describe the adsorption kinetics of copper ions well, and the Freundlich model provides an excellent fit to the adsorption isotherm. XRD and FTIR were applied to characterize the raw materials and adsorbents to reveal the adsorption mechanism. The results suggest that the adsorbent converted from MSR is a promising material for the removal of Cu(II) in aqueous solutions.

The increasing number of applications of nanoparticles (NPs) in various fields has led to negative effects on the environment. In this study, the effects of CuO nanoparticles (CuO NPs) on Arabidopsis root tips were investigated. Significant growth inhibition on Arabidopsis roots was observed after treatment with both CuO NPs (10 mg/L) and the correspondingly released Cu²⁺ (0.80 mg/L). Scanning electron microscope images demonstrated that NPs primarily deposited on the surface of root tips and penetrated intercellular spaces after CuO NP exposure. Light and fluorescence microscope visualization revealed that the root tips were damaged severely after CuO NP exposure, with swelling of the hair zone, splitting of the cell wall junction, and disordered cell arrangement in the root tip. Semiquantitative analysis by Fourier transform infrared spectroscopy demonstrated that the cell wall xyloglucan and esterified pectin contents in the roots were decreased. Similar but weaker effects on the roots were detected after Cu²⁺ treatment. Additionally, some genes related to cell wall organization were downregulated by CuO NP stress, partially contributing to the cell wall component change. The results demonstrated that CuO NPs produced phytotoxicity to the cell wall through both physical damage and biochemical disruption, causing loosening of the tethers between cellulose microfibrils in the cell wall and the disruption of cell adhesion. The phytotoxicity of CuO NPs in the plant cell wall was mainly caused by NPs and was partially related to the released Cu²⁺. These findings are helpful to understand better the negative effects of CuO NPs on plant regarding the cell wall.

Phosphorus (P) is an essential biogenic element in aquatic ecosystem, and its speciation in sediment may influence the water quality. The composition of P in suspended particular matters (SPM) and sediments were analyzed. Metal ions bonding PO₄³⁻ and chelating organic P (OP) were explored by Visual MINTEQ simulation and infrared spectroscopy. Inorganic P (IP) mainly comprises orthophosphate and pyrophosphate in SPM. OP mainly includes α-glycerol phosphate, β-Gly, monophosphate, and mononucleotides from aquatic plants in SPM. Cyclotella, Nitzschia, Amphiprore, and terrestrial C₃ plants are the main source of aquatic plants in JH, while they are from Oscillatoria and Merismopedia in JL. These aquatic plants directly determine whether OP or IP is taken to surface sediments during the setting of SPM. The bonding between PO₄³⁻ and Ca is more preferential than Al and Fe, so the excess PO₄³⁻ makes Ca compounds bonding IP (Ca-IP) and Al/Fe/Mn (hydr) oxides associated IP (Al/Fe/Mn-IP) dominant, but limited PO₄³⁻ preferentially contributes more Ca-IP. Metal ions in saline water can firmly cheat with OP via P-OH and/or P=O groups to promote the burial of OP.

An iron(III)-polyvinyl chloride (PVC)-Schiff base adsorbent was prepared for removal of methyl orange (MO) as an anionic dye from the aqueous samples. PVC was reacted with ethylenediamine to prepare aminated PVC. Salicylaldehyde was then added to the aminated PVC to incorporate the Schiff base group into the polymer structure. This product was further reacted with iron (III) nitrate to form an iron complex as the modified PVC adsorbent (PVC-[Fe(EDA)(Sald)]). The prepared adsorbent was characterized by Fourier transform-infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area analysis, and thermogravimetric analysis (TGA). The special parameters influencing the adsorption process such as the solution pH, contact time, initial dye concentration, and the solution temperature were investigated. Removal percentage (%R) and adsorption capacity (qₜ) greater than 50% and 140 mg g⁻¹, respectively, were obtained under the following conditions: pH, 7;contact time, 150 min; dye concentration, 100 mg.L⁻¹; and solution temperature, 25 °C. The adsorption isotherm and kinetic data were well fitted by the Freundlich isotherm model and the pseudo-second-order kinetic model, respectively. The thermodynamic data revealed that the adsorption process was endothermic and spontaneous. The changes in entropy (ΔS°) and enthalpy (ΔH°) were calculated to be 0.110 kJ mol⁻¹ K⁻¹ and 31.011 kJ mol⁻¹, respectively. In this work, we developed for the first time the synthesis of an iron(III)-polyvinyl chloride (PVC)-Schiff base adsorbent that can be successfully used for removal of methyl orange from the aqueous sample. Furthermore, these findings showed that modified PVC was more efficient than neat PVC on MO removal for adsorption process.

This paper presents an analysis of contaminants generated from large-scale, laboratory-based, underground coal gasification (UCG) experiments using a high-rank coal from the South Wales Coalfield. The experiments were performed at atmospheric and elevated pressures (30 bar) by varying the oxidants’ composition. The experiments were designed to predict the amount of produced water and contaminants generated at each stage of the operating conditions. The mass balance of water supplied and produced in the experiments was accounted for. Chemical analyses of produced water, char and ash contents were performed to quantify the inorganic and organic chemical parameters. Most of the contaminant concentrations in the produced water from the 30-bar pressure experiment were lower than the concentrations generated from the atmospheric pressure experiment. The measured concentrations of the inorganic chemical species and the inorganic parameters of the coal seam water from the South Wales Coalfield were used in theoretical calculations to predict the dominant equilibrium species concentrations in a hypothetical scenario of effluent contaminated groundwater. The biodegradation of organic contaminants such as phenol, benzene and sorbed fractions of inorganic contaminants from the produced water on iron oxide in the ash residue was predicted using existing biotransformation kinetics and surface complexation models, respectively. The biodegradation of phenol and benzene would be a slow process even at optimum conditions and the iron oxide left in the cavity can act as a sorbent for a few inorganic species. The evidence from the present study suggests future work towards (i) developing an appropriate water treatment process during gas cleaning, (ii) operational procedure (pressure and proportions of oxidant) and (iii) developing UCG-specific experimental prediction of contaminant transportation and transformation kinetics. Graphical abstract

Chloramination of drinking water and wastewater can generate carcinogenic nitrosamines, among which, nitrosodipropylamine (NDPA) with large molecular weight and weak polarity has been commonly found. However, knowledge on the formation of NDPA remains highly limited. Laboratory tests were conducted to quantify NDPA formation during chloramination of nitrogenous precursors, including dipropylamine and methyldipropylamine, and pesticides such as trifluralin, oryzalin, and vernolat. Results showed that all precursors exhibited > 10.0% NDPA yields after 24 h. Oryzalin and trifluralin accomplished the highest (13.63%) and lowest (11.31%) yield, respectively. Maximal yields of all precursors were observed at pH 9.0 and temperature 288 K. Maximums of NDPA yield from oryzalin (18.27%) and vernolat (19.54%) were formed at Cl:N of 0.7:1.0, but maximal yields of dipropylamine (18.44%), methyldipropylamine (22.98%), and trifluralin (33.06%) were achieved at Cl:N of 1.2:1.0. Maximal NDPA yields of dipropylamine (37.14%), methyldipropylamine (32.84%), and vernolat (49.02%) were observed at [NH₂Cl]₀:[precursor]₀ = 500, but highest yields of trifluralin (30.24%) and oryzalin (25.53%) were accomplished at [NH₂Cl]₀:[precursor]₀ = 50. Bromide and organic contents in tap and raw water reduced NDPA due to competition for NH₂Cl. Chloramination of water impacted by amines and pesticides should be careful of NDPA formation.

This study evaluated Cr(VI) biosorption by a halotolerant gram-negative bacterium Halomonas sp. DK4 isolated from chrome electroplating sludge. The bacterium could withstand high concentrations of Cr(VI) exhibiting a minimal inhibitory concentration (MIC) of 250 mg/L. Plackett–Burman design confirmed glucose, KH₂PO₄, NaCl, inoculum size, and initial Cr(VI) concentration as significant variables influencing the Cr(VI) removal ability of the bacterium. The suspended culture of Halomonas sp. DK4 was able to remove 81% (100 mg/L) of Cr(VI) in optimized MSM medium from aqueous solutions within 48 h. The bacterium also removed 59% Cr(VI) in the presence of 15% NaCl concentration within 72 h. The main mechanism involved in Cr(VI) removal by Halomonas sp. DK4 was determined to be biosorption which was best explained using the Langmuir isotherm model, wherein the maximum adsorption of 150.7 mg/g was observed under equilibrium conditions. Kinetic studies reveal that chemisorption of Cr(VI) by Halomonas sp. DK4 was a rate-limiting process which followed pseudo-second-order kinetics (R² = 0.99). Bacterial biomass exhibited maximum adsorption of 70.3% Cr(VI) at an initial concentration of 100 mg/L under optimal conditions. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the presence of hydroxyl, carboxyl, amide, and phosphate groups on the bacterial surface which may be involved in Cr(VI) adsorption. Scanning electron microscopy coupled energy dispersive X-ray (SEM-EDX) analysis revealed morphological changes in the bacterial cell and accumulation of Cr(VI) on the cell surface. These results suggest the potential application of Halomonas sp. DK4 in the removal of Cr(VI) from saline chromium-containing industrial wastewaters.

Wastewater treatment plants (WWTPs), usually designed to remove organic pollutants and nutrients, are often poorly equipped to handle pathogens. The present study investigated the multiple barriers provided by WWTPs to understand their role in spreading pathogenic bacteria into the environment. Three types of WWTPs (hospital, domestic, and mixed) differing in the source of raw influent, operating parameters, and reactor configuration (biological and tertiary treatment processes) were compared for the presence of fecal indicators and pathogenic bacteria discharged in their treated effluents. The plate-count technique was used for bacterial enumeration on selective agar. The microbial quality of the treated effluent was observed to be strongly influenced by characteristics inherent to a WWTP rather than depending on the characteristics of the raw influent. Among the different configurations studied, membrane bioreactor (MBR) treatment followed by chlorine disinfection provided an effluent of the highest quality (100% bacterial removal rates) followed by moving bed bioreactor (MBBR) combined with UV disinfection. MBR treatment greatly increased the efficiency of chlorine disinfection. Higher total suspended solids (TSS) removal corresponded to higher bacterial removal rates. Tertiary treatment proved to be an important determinant of the microbial quality of the final effluent. A great heterogeneity was observed in the removal rates of different bacterial groups with different treatment processes. The highest removal was observed in the case of indicators and least in the case of emerging pathogens like Escherichia coliO157: H7 indicating a lack of correlation between traditional indicators and emerging pathogens and also the inefficiency of the current wastewater treatment technologies in dealing with emerging pathogens.