This paper attempts to investigate the emissions embodied in Australia’s economic growth and disaggregate primary energy sources used for electricity production. Using time series data over the period of 1990–2012, the ARDL bounds test approach to cointegration technique is applied to test the long-run association among the underlying variables. The regression results validate the long-run equilibrium relationship among all vectors and confirm that CO₂ emissions, economic growth, and disaggregate primary energy consumption impact each other in the long-run path. Afterwards, the long- and short-run analyses are conducted using error correction model. The results show that economic growth, coal, oil, gas, and hydro energy sources have positive and statistically significant impact on CO₂ emissions both in long and short run, with an exception of renewables which has negative impact only in the long run. The results conclude that Australia faces wide gap between emission abatement policies and targets. The country still relies on emission intensive fossil fuels (i.e., coal and oil) to meet the indigenous electricity demand.

Due to their metal removal ability, bacterial biosorbents can be effectively used for the treatment of wastewaters containing heavy metals. Searching for bacterial biosorbents for hazardous heavy metals like cadmium is a pivotal for remediation efforts. The gene cadA, that mediates resistance to cadmium over an ATP-dependent efflux mechanism, provides a good target for the selection of potential cadmium biosorbents. For this reason, in this study, a 36-mer-oligonucleotide DNA probe based on the entire 3.5-kb BglII-XbaI fragment of cadA operon from staphylococcal plasmid pI258 was prepared by using Vector NTI Express software. Under the hybridization conditions of 46 °C, 50 % formamide, and 0.028 M NaCl, the designed cadA probe appeared to be highly specific to the cadA-positive Staphylococcus warneri and Delftia acidovorans isolates tested. The results indicated that the newly designed cadA-targeted DNA probe has potential as a specific, sensitive, and quantitative tool in selecting and in situ screening of potential cadmium biosorbents.

Thallium is a non-essential, toxic element that concerns mining areas and their acid drainage effluents. Minerals containing thallium can be eroded, and Tl can be leached into soil, thus being spread into the environment and adsorbed by plants and living organisms, entering the food chain, and inducing serious toxicity problems. In this study, the Tl cycle was observed and analyzed on basil, mint, and strawberry cultivated in a greenhouse and irrigated with Tl-contaminated water. The Tl content in both bulk and rhizosphere soils as well as thallium present in different plant organs were analyzed during the experiment, with the aim of revealing both physiological symptoms and metabolic disorders linked to the Tl toxicity. The mechanism of plants to exclude, uptake, translocate, and tolerate Tl varied among the different species, and both the bioconcentration factor (BCF) and the translocation index (TI) were calculated to highlight a different response to Tl toxicity of strawberry, mint, and basil. Basil is the less tolerant species, while mint and strawberry showed different self-defense mechanism against Tl adsorption and translocation.

As major endocrine disruptors, natural estrogens such as 17β-estradiol (E2) have been found with adverse effects on animals and humans. How to control E2 pollution as well as that of other estrogens in the environment is a worldwide concern. A novel E2-degrading bacterium (strain JX-2) was isolated from the activated sludge of a sewage treatment plant and was identified as Rhodococcus sp. Strain JX-2 grew well and metabolized up to 94 % of the substrate E2 added (30 mg L⁻¹) within 7 days at 30 °C. The optimal environmental conditions for E2 degradation by JX-2 were pH 7.0 and 30 °C. Strain JX-2 was immobilized in sodium alginate. The optimal conditions for strain JX-2 immobilization were 4 % sodium alginate, 1:1 bacteria/sodium alginate ratio, 5 % CaCl₂⋅2H₂O, and 6 h crosslinking time. The degradation performance of immobilized strain JX-2 was apparently superior to that of the free strain, particularly under pH <6.0 or >8.0 either below 20 or above 35 °C. Immobilized strain JX-2 removed E2 in natural sewage and cow dung with removal efficiency of more than 64 and 81 %, respectively. This is the first report of utilizing immobilized bacteria to remove estrogens in sewage and livestock manure. The results suggest that strain JX-2 could be used to remove E2 from the environment efficiently.

Iron (Fe) nutrition status and activity of Fe-dependent enzymes is suggested to be affected by air pollution. This study was aimed to investigate changes in leaf Fe, zinc (Zn), chlorophyll (a, b), and carotenoid concentration and activity of catalase (CAT) and peroxidase (POX) in the leaves of maple (Acer negundo L.) with distance from two major sources of air pollution, i.e., Oil Refinery of Shiraz (ORS) operations and urban traffic of Imam Hossein square (AS) in Shiraz, Iran. By increasing the distance from the ORS, Fe, Zn, and chlorophyll concentration in the maple leaves increased. These changes were associated with lower intensity of chlorosis symptoms on the leaves of maple trees with distance from the ORS. Leaf activity of CAT increased with increasing distance from the ORS. Changes in concentration of carotenoids and activity of POX did not follow a distinct trend with distance from both pollution sources. No regular pattern was observed for changes in the measured parameters with distance from the urban traffic of Imam Hossein square (AS), as another major source of air pollution in the studied region. This was due to irregular changes in the concentrations of air pollutants across the sampling pathway. According to the results, significant impairment in Fe nutritional status is expected for plants exposed to the air pollution, although further studies are needed to clarify the physiological reasons of Fe chlorosis under air pollution stress.

Sorption and desorption of heavy metals (Cd, Cu, Pb, and Zn) was evaluated in biochars derived from sugarcane bagasse (SB), eucalyptus forest residues (CE), castor meal (CM), green coconut pericarp (PC), and water hyacinth (WH) as candidate materials for the treatment of contaminated waters and soils. Solid–liquid distribution coefficients depended strongly on the initial metal concentration, with K d,ₘₐₓ values mostly within the range 10³–10⁴ L kg⁻¹. For all biochars, up to 95 % removal of all the target metals from water was achieved. The WH biochar showed the highest K d,ₘₐₓ values for all the metals, especially Cd and Zn, followed by CE (for Cd and Pb) and PC (for Cd, Pb, and Zn). Sorption data were fitted satisfactorily with Freundlich and linear models (in the latter case, for the low concentration range). The sorption appeared to be controlled by cationic exchange, together with specific surface complexation at low metal concentrations. The low desorption yields, generally less than 5 %, confirmed that the sorption process was largely irreversible and that the biochars could potentially be used in decontamination applications.

In this paper, a method using liquid-liquid microextraction in a dynamic system combined with spectrophotometry was developed for preconcentration and determination of lead in samples of shrimp and oyster. In the procedure, a system is proposed in which the organic drop is maintained at the bottom of a glass tube, with the passage of a stream of aqueous solution, avoiding the use of a microsyringe. The method is based on the transfer of metal species present in the aqueous phase in the form of complexes with the ligand 2-(5-bromo-2-pyridylazo)-5-dimethylaminophenol (5-Br-PADAP) to the organic phase trichloroethylene. Experimental conditions, such as sample flow rate, concentration of the complexing reagent, extraction solvent, time of extraction, and pH, were optimized. Under optimized conditions, the limit of detection and quantification obtained were 0.48 and 1.60 μg L⁻¹, respectively. The accuracy was evaluated by the determination of lead in the certified reference material BCR-414, Plankton. The procedure was applied to the determination of lead in samples of shellfish, with recoveries ranging from 92 to 103 %. The method enabled a fast, accurate, and simple alternative for the determination of lead in seafood samples.

A groundwater flow and mass transport model simulated the remediation capability of non-pumped wells with filter media placed in backfilled trenches in homogeneous and heterogeneous aquifers. For each of five homogeneous and heterogeneous aquifer settings, the model identified a base configuration of wells for a backfill hydraulic conductivity equal to the mean of the aquifer (1.5 m/d). Base configurations comprised the least number of wells necessary to contain and remove a contaminant plume. For each setting, the model also simulated base configurations with backfill hydraulic conductivity one and two orders of magnitude lower and one and two orders of magnitude higher than the mean of the aquifer. In general, backfill with a hydraulic conductivity equal to the mean of the aquifer, or slightly higher, outperformed other scenarios.

Sorption equilibria of copper(II) ions onto palygorskite and sepiolite clay minerals were studied as a function of temperature. The experimental data were fitted to the Langmuir, Freundlich, Temkin, and R-D models to obtain the isothermal constants. van’t Hoff, Gibbs, Clausius–Clapeyron, and modified Arrhenius equations were also employed to evaluate the thermodynamic parameters involved in Cu sorption. The results showed that fibrous clay minerals exhibit enhanced Cu(II) sorption capacities at higher temperatures. Enthalpy changes (ΔH°) were found to be positive, confirming that the process of Cu(II) sorption on both palygorskite and sepiolite was endothermic. Positive values were also obtained for the entropy changes (ΔS°), which suggests increased randomness at the solid-solution interface during the sorption of Cu(II) ions on both fibrous clay minerals investigated. The free energy changes (ΔG°) were negative for all the different temperatures and initial Cu(II) concentrations tested, indicating that sorption on the minerals is spontaneous and favorable. It was, therefore, concluded that sorption of Cu(II) ions on fibrous clay minerals is entropically driven. The values of isosteric heat of sorption (∆H ₓ) decreased with increasing sorption density, which shows that the clay surface is heterogeneous in terms of the active sites available for Cu(II) retention. The values of activation energy (E ₐ) and sticking probability (S *) generally lied within the ranges associated with physisorption for palygorskite and chemisorptions for sepiolite. In conclusion, the thermodynamic parameters investigated revealed the higher tendency and capacity of sepiolite, compared to palygorskite, for the feasible, spontaneous, and endothermic retention of Cu(II). However, the intensity of Cu(II) interactions with the fibrous clay minerals was found to depend to a large extent on the temperature and the initial Cu loading of the systems.

Acid mine drainage (AMD) is a persisting environmental problem and a grievous nuisance in the mining sector. In this study, iron (Fe(II)) removal was tested in AMD samples collected from the Enugu Okpara abandoned coal mine (Nigeria), having iron concentrations of ∼1300 mg/l. Digestion, toxicity characteristic leaching procedure (TCLP), and batch adsorption tests using coal bottom ash (BA), bentonite clay (BC), and coal fly ash (FA) were performed. Apart from elucidating the effects of adsorbent dose and initial Fe(II) concentrations on the maximum adsorption capacity (q ₑ) of the adsorbents, the experimental data were also fitted to well-known adsorption isotherms and kinetic models. The results from batch tests showed that the optimum adsorbent dosages for BA, BC, and FA were found to be 3, 4, and 4 g per 100 ml, respectively. Among the different adsorption isotherm models tested, the Temkin model fitted the experimental data well for Fe(II) removal. Results from kinetic analysis showed that the Fe(II) removal efficiency increased with an increase in the contact time and then remained almost constant after 30 min for the three tested adsorbents.