In this study, we attempt to prospect potential bacterial isolates from mangrove sediments of Mangalavanam, Kerala, India, with positive carbonic anhydrase (CA) activity to sequester carbon dioxide by calcium precipitation process. Fifteen bacterial colonies (M1–M15) isolated were screened for their carbonic anhydrase enzyme production potential based on p-nitro phenol acetate assay. Based on the secondary screening, M3 and M8 were identified as the most potential for carbonic anhydrase production. The specific activity of the partially purified CA enzyme from M3 and M8 were 44 U mg⁻¹ and 76 U mg⁻¹ respectively. The enzyme activity increased by 1.6-fold upon precipitation by acetone (80%). The potential isolate which higher CA production, M8 was identified as Bacillus altitudinis based on 16S rDNA sequencing. Soil microcosm was established to study carbonic anhydrase production and CO₂ sequestration ability of B. altitudinis M8 strain. B. altitudinis M8 strain could reduce CO₂ by 75 ± 0.12% in microcosm composed of sterilized soil with bacteria (SSB) and by 97 ± 0.34% in microcosm with sterile soil with enzyme (SSE). Hence, the application of enzyme was found to be more effective in removing CO₂ when compared to bacterial inoculum. To further understand the bio-mineralization ability of this microbial isolate, calcium precipitation assay was conducted. There was a reduction of 42.22 ± 0.23% of free calcium in the medium through calcite precipitation. The carbonic anhydrase-mediated calcium precipitation by B. altitudinis M8 strain could be effectively employed in the process of carbon dioxide sequestration.

Methane (CH₄) and nitrous oxide (N₂O) are two important greenhouse gases (GHG) and contribute largely to global warming and climate change. The impact of physiological characteristics of rice genotypes on global warming potential (GWP) and greenhouse gas intensity (GHGI) is not well documented. A 2-year field experiment was conducted with eight summer rice varieties: Dinanath, Joymoti, Kanaklata, Swarnabh, IR 64, Tapaswami (modern varieties), Number 9, and Jagilee Boro (indigenous varieties) for two successive seasons (December–June, 2015–2016 and December–June, 2016–2017) to estimate their GWP and GHGI. The GWP of the rice varieties ranged from 841.52 to 1288.67 kg CO₂-equiv. ha⁻¹ and GHGI from 0.184 to 0.854 kg CO₂-equiv. kg⁻¹ grain yield. Significant differences (p < 0.05) in seasonal GHG emission, GWP, GHGI, CEE (carbon equivalent emission), photosynthetic efficiency, stomatal conductance, transpiration rate, and grain productivity among the rice varieties were observed during the investigation. A good correlation of GWP (p < 0.01) was recorded with rate of stomatal conductance and transpiration rate of the varieties. The present study reveals a strong relationship between plant biomass (p < 0.01) with GWP and CEE of the rice varieties. The variety IR 64 and Number 9 are identified as the most suitable variety with lowest GWP (909.85 and 876.68 kg CO₂-equiv. ha⁻¹ respectively) and GHGI (0.192 and 0.227 kg CO₂-equiv. kg⁻¹ grain yield respectively) accompanied by higher grain productivity (4839 and 3867 kg ha⁻¹ respectively). Observations from the study suggest that agricultural productivity and GHG mitigation can be simultaneously achieved by proper selection of rice genotypes.

Ammonia is one of the most common aquatic pollutants. To analyze the effect of ammonia exposure on the glutathione redox system, we investigated the levels of hydrogen peroxide (H₂O₂) and glutathione, and transcription and activities of glutathione-related enzymes in liver and gills of FFRC strain common carp (Cyprinus carpio L.) exposed to 0, 10, 20, and 30 mg/L of ammonia. The results showed that H₂O₂ content reached a maximum level at 48 h of exposure in the liver of fish. In gills, H₂O₂ increased rapidly at 6 h and reached to maximum levels at 24 h of exposure, indicating that gills experienced oxidative stress earlier than the liver of fish exposed to ammonia. Reduced glutathione (GSH) content and reduced glutathione/oxidized glutathione (GSH/GSSG) ratio increased significantly within 24 h of exposure. Meanwhile, the transcription and activities of glutathione S-transferase (GST) and glutathione reductase (GR) increased significantly in the liver, and glutathione peroxidase (GSH-Px) and GST increased in the gills of fish exposed to ammonia. Malondialdehyde (MDA) content kept at a low level after exposure to low concentration of ammonia, but increased significantly after exposure to 30 mg/L ammonia for 48 h along with a decrease in GSH content and GSH/GSSG ratio. These data showed that the glutathione redox system played an important role in protection against ammonia-induced oxidative stress in the liver and gills of FFRC strain common carp, though the defense capacity was not able to completely prevent oxidative damage occurring after exposure to higher concentration of ammonia. This research systematically studied the response of the glutathione redox system to ammonia stress and would provide novel information for a better understanding of the adaptive mechanisms of fish to environmental stress.

Since decades, surface water bodies have been exposed to pesticides from agriculture. In many places, retention systems are regarded as an important mitigation strategy to lower pesticide pollution. Hence, the processes governing the transport of pesticides in and through a retention system have to be understood to achieve sufficient pesticide attenuation. In this study, the temporal dynamics of metazachlor and its transformation products metazachlor-oxalic acid (OA) and –sulphonic acid (ESA) were observed in an agricultural retention pond and hydrologic tracers helped to understand system-inherent processes. Pesticide measurements were carried out for 80 days after their application during transient flow conditions. During a short-term (3 days) experiment, the tracers bromide, uranine and sulphorhodamine B were used to determine hydraulic conditions, residence times and sorption potential. A long-term experiment with sodium naphthionate (2 months) and isotopes (12 months) provided information about inputs via interflow and surface-groundwater interactions. During transient conditions, high concentration pulses of up to 35 μg L⁻¹ metazachlor, 14.7 μg L⁻¹ OA and 22.5 μg L⁻¹ ESA were quantified that enduringly raised solute concentrations in the pond. Mean residence time in the system accounted for approximately 4 h showing first tracer breakthrough after 5 min and last tracer concentrations 72 h after injection. While input via interflow was confirmed, no evidence for surface-groundwater interaction was found. Different tracers illustrated potentials for sorption and photolytic degradation inside the system. This study shows that high-resolution sampling is essential to obtain robust results about retention efficiency and that hydrological tracers may be used to determine the governing processes.

This study aims to investigate the long-run and causal effects of energy consumption, economic growth, urbanization, and trade openness on CO₂ emissions in Turkey using newly developed econometric techniques. To our best knowledge, there has been no study examining the relationship between CO₂ emissions, energy consumption, trade openness, urbanization, and economic growth in Turkey. Therefore, this study proposes to fill this gap in the literature. In this study, we use time series data covering the years between 1960 and 2015. To capture long-run effects, we used ARDL, FMOLS, and DOLS estimators, while wavelet coherence technique is used to explore causal effects among the variables. Our results reveal that (i) there is a long-run equilibrium relationship between CO₂ emissions and energy consumption, economic growth, urbanization, and trade openness; (ii) in the long-run, CO₂ emission in Turkey is significantly triggered by energy consumption, economic growth, and urbanization; and (iii) the results of the wavelet coherence–based causality test provide supportive evidence to the long-run estimations of this study.

Sorption of oil-related products (including mainly the propellants) is the very basic process that counteracts spreading these types of pollution into environment. Plenty of synthetic substances (including the monoaromatic hydrocarbons) are both from the surface and underground waters. The aim of this study was to present the research’s results on the possibilities of using the broadleaf cattail (Typha latifolia L.) seeds as a sorbent of monoaromatic hydrocarbons from an aqueous solution. In order to increase sorptive capacity, the seeds biomass was submitted for the process of mercerizing in diversified time and temperature in water and the NaOH solution. The removal of benzene, toluene, ethylbenzene, o-xylene, m-xylene and cumene was carried out by means of the “batch method”. All the conducted experiments have shown a high sorption level of the analysed pollutions from an aqueous solution. The best sorptive qualities appeared in the seeds drenched in 80 °C water for 4 h (W) 97 g/kg, what was 9.06% more absorbed hydrocarbons in comparison to the control sample (C) and 26.8% more than the smallest seeds drenched in NaOH for 240 min. in the temperature of 80 °C (N). The process of the seeds mercerizing that was conducted with the use of hot water appeared to be most effective, but seeds without mercerisation (C) is actually the material which absorbs the least amounts of energy for preparation and had quite good sorption capacity too.

The utilization of construction and demolition waste materials for the radionuclide immobilization by sorption processes was investigated. Given that the liquid radioactive waste usually has a complex composition and that effects of competition may significantly influence the efficiency of the treatment, the Simplex Centroid experimental design was used to explore ions sorption from multi-component solutions. For the purpose of this study, the common components of construction and demolition waste, such as pathway concrete and different bricks samples, were used along with the multi-component Sr²⁺, Co²⁺, and Ni²⁺ ions solutions. The equations for the prediction of metal ions sorption capacities were derived. The coefficients that correspond to the linear and interaction terms were obtained using a special cubic model. Likewise, by analysis of variance, statistically significant terms of the obtained polynomial were defined. The investigation has shown that the most effective sorption was onto the pathway concrete for all three cations, while the highest sorption capacity was found for Co²⁺ ions. Also, it has been determined that concerning Sr²⁺ ion removal there was a competition with coexisting Co²⁺ and Ni²⁺ ions, reducing its sorption capacity, while sorption of Co²⁺ and Ni²⁺ occurred more independently on other cations in multi-component solutions. Based on the obtained results, the applied experimental design can be efficiently used for the description of competitive sorption process and could be a powerful tool for the prediction of cation immobilization in liquid radioactive waste treatment.

Widely consumed benzodiazepine drugs are emerging contaminants, some of them being endocrine disruptors. Although many of these drugs remain in wastewater even after conventional treatment, innovative treatability studies are still sparse. The aim of this study was to investigate the efficiency of heterogeneous photocatalysis using synthesized composites based on TiO₂ and activated carbon (TiO₂/AC) as catalysts under sunlight-simulated irradiation. Different ratios and calcination temperatures were tested for the synthesis, and the composite with the best photocatalytic efficiency (based on methylene blue dye removal from water solution) was the one formed by 10% AC calcined at 400 °C (TiO₂/AC10%). This composite was applied in heterogeneous photocatalysis to remove bromazepam, clonazepam, and diazepam at environmentally relevant concentrations (100 μg/L). Such treatment approach has not been reported in the literature to date. Independent variables such as catalyst concentration, pH, and sunlight-simulated irradiation were studied using design of experiments (DoE) to find conditions that provide maximum removal efficiency. TiO₂/AC10% powder was characterized by SEM, XRD, BET, and diffuse reflectance. Under feasible optimized conditions, the efficiency of TiO₂/AC10% to remove benzodiazepine drugs from water was > 97.5%, which is much higher than the removal obtained with commercial catalyst and all controls.

Three-dimensional fluorescence spectrometer was adopted for the content analysis of different types of organics in coking wastewater before biochemical treatment and through biochemical treatment, and the model of parallel factors was employed to analyze fluorescence components and contents. It was found that tryptophan-like components were the most easily degraded by biology, while humic-like components were the least easily degraded. Meanwhile, it had been seen that the change trends over time of total fluorescence densities of proteinoid fluorescence, and degradable organic fluorescence were highly consistent with that of parameter values of COD, NH₃-N in this wastewater after analyzing the trends of the two indexes. It was proved that the three-dimensional fluorescence spectrum method was appropriate for the accurate degradation analysis of wastewater components.

The aim of this work was to study the adsorption kinetic, isotherm, and thermodynamic of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide in raw and boiling-treated sterile bracts of Araucaria angustifolia as novel alternative natural adsorbents. The sterile bracts were characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. The adsorption and removal of 2,4-D from aqueous solutions were conducted at different contact times, bract granulometries, solution pH, bract masses, initial 2,4-D concentrations, and temperatures. The adsorption kinetic, mechanism, and thermodynamic were evaluated using pseudo-first- and pseudo-second-order kinetic models, non-linear Langmuir, Freundlich, Redlich-Peterson and Sips isotherm models, and Gibbs free energy, enthalpy, and entropy. The maximum removal efficiency of 2,4-D was found with 720 min of contact, 5.0 g of bract containing 31 micron particle sizes, pH = 2.0, and room temperature. The best kinetic and isotherm fits were found with the non-linear pseudo-second-order kinetic model and non-linear Freundlich isotherm model, respectively. Therefore, the adsorption mechanism in the bract structure takes place with multi-layer formation and multi-site interactions due to chemisorption reactions. The adsorption process is thermodynamically favorable, spontaneous, and exothermic. Overall, sterile bract of Araucaria angustifolia could be useful as alternative natural adsorbent for the treatment of water and wastewater contaminated with 2,4-D, mitigating the environmental pollution caused by agricultural crops. Graphical Abstract