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.

The petroleum production has been raised sharply over the past decades, whereas the petroleum exploitation has also caused serious environmental contamination. A pot experiment has been conducted to monitor the dynamic response of antioxidant defense system and the growth reaction of Amorpha fruticosa seedlings to soil petroleum contamination. The results show that (1) in 5 g kg⁻¹ contaminated soil, A. fruticosa removes reactive oxygen species (ROS) by increasing the activities of antioxidant enzymes (glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT)), while in 10–15 g kg⁻¹ long-term contaminated soil, A. fruticosa removes ROS by the cooperation of antioxidant enzymes and antioxidants (SOD, CAT, ascorbate peroxidase (APX), GR, ascorbic acid (AsA), glutathione (GSH), and proline (Pro)). In long-term 20 g kg⁻¹ contaminated soil, the defense ability of APX and AsA decreases sharply, and A. fruticosa removes the ROS by the synergistic effect of antioxidant enzymes (SOD and CAT) and antioxidants (GSH and Pro). Only in 20 g kg⁻¹ long-term petroleum contamination caused significant (P < 0.05) increase in H₂O₂ content in seedlings. (2) SOD, CAT, GR, GSH, and Pro exhibit increases in long-term severely contaminated soil, and these enzymes and antioxidants are the most important defender of A. fruticosa to ROS accumulation caused by petroleum contamination. (3) The growth of A. fruticosa seedlings is less affected in 5 g kg⁻¹ petroleum-contaminated soil, while it significantly decreases in 10, 15, and 20 g kg⁻¹ petroleum-contaminated soils (P < 0.05). (4) Considering comprehensively the response of antioxidant defense system and the growth reaction of seedlings to petroleum contamination, A. fruticosa could be utilized for phytoremediation in ≤15 g kg⁻¹ contaminated soil.

This study evaluated the possibility of improving the macronutrient status of Cd-stressed white mustard ‘Rota’ using intensive S nutrition. Three S-SO₄ (2, 6, 9 mM S) and four CdCl₂ doses (0, 0.0002, 0.02, 0.04 mM Cd) in the Hoagland’s nutrient solution were conducted for 14 days. High S supply (6 or 9 mM) appears, to some extent, to affect positively the macronutrient status of Cd-stressed mustard. It increased roots and shoots contents of K and S, without significant changes in P content. Simultaneously, Mg content in shoots and roots remained stable, but Mg bioaccumulation was elevated. Shoot Ca content at the lowest and medium Cd dose decreased, whilst was unaffected at the highest Cd treatment. Intensive S nutrition of Cd-stressed mustard increased root N content and accumulation at the highest Cd concentration, but the N content dropped in above-ground parts. The bioaccumulation of remained macronutrients in general was substantially elevated together with enhanced Cd accumulation. Thus, the intensive S nutrition can enhance mustard tolerance to Cd stress by improvement macronutrients relations in plants, and S supplementation may be recommended for mustard cultivation on the Cd-contaminated areas.

The effects of soil micro-particles and micro-pores on the release of total petroleum hydrocarbons (TPH) were investigated using long-term weathered, TPH-contaminated soil samples. The TPH concentrations were analyzed using various extraction schemes (i.e., total extraction, weak extraction, solvent extraction with or without ultrasound). The particle size distribution (<2 mm, 0.063–2 mm, <0.063 mm), micro-pore volume (<0.38 mm), and TPH fraction (C8–14, C16–28, C30–40) of selected samples were also determined to better understand the factors controlling TPH release from contaminated soils. TPH concentrations varied greatly among different fractions of each soil sample, but were highest in the micro-fraction (<0.063 mm) of each sample. In weathered soil samples, TPH was not only weakly or strongly adsorbed on soil particles, but also trapped in soil micro-pores. Moreover, heavier fractions of TPH were released slowly and lesser extent from contaminated soils. Results showed that the solvent extraction method with and without ultrasound could be used to assess relative binding strength of TPH to contaminated soils. These findings imply that to achieve a remediation goal, some contaminated soils require only relatively mild extraction with solvent, but soils with TPH trapped in micro-pores require physical destruction along with chemical extraction.

The bulk deposition of both PAHs and metals is a significant, mounting issue for the urban ecological environment. However, studies generally performed on these pollutants have focused on the regions surrounding a pollution source; thus, it most likely overestimated pollutants in the cities. Therefore, 72 atmospheric bulk deposition samples were collected from six sites located along a transect from the suburbs to the city center in Shanghai over a 1-year period (February 1, 2012 to January 31, 2013). The seasonal variation, spatial distribution, and sources of multiple metals (Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, K, Na, and Mg) and 16 polycyclic aromatic hydrocarbon (PAH) compounds were determined. The results indicated that the annual average rate of dust deposition in Shanghai was 43,100 ± 54,800 mg/m²/year. There were significant or high enrichments of Cu, Zn, Cd, and Pb, and higher depositional fluxes were observed for Zn, Pb, and Cd in the Huangpu district and for Cu in the Minhang district. The deposition fluxes of the PAHs exhibited the following order: urban fringe zone > city center > rural zone (background site). However, unlike in northern Chinese cities, the high-molecular-weight PAHs accounted for most of the PAHs. Furthermore, there were higher depositional fluxes of PAHs in March, July, and October. Overall, the factors influencing urban air quality may include construction, fossil fuel combustion, the abrasion of tires and brake linings (directly related to traffic), the corrosion of galvanized protection barriers, and increasing population density.

The mass spectrometric analysis of the impact of sulfur dioxide and dust emission on carbon and oxygen stable isotopic compositions of glucose hydrolysed from α-cellulose samples extracted from Scots pine growing in the vicinity of “Huta Katowice” steelworks was the main aim of this study. The annual rings covered the time span from 1975 to 2012 AD. The relationships between climatic conditions, sulfur dioxide, and industrial dust emission and oxygen and carbon isotopic compositions were analyzed using correlation function methods. This study shows the first analysis of carbon and oxygen stable isotopes in glucose as the bio-indicators of CO₂, sulfur dioxide, and industrial dust emission. The anticoincidence trend of δ¹⁸O and δ¹³C and dust and sulfur dioxide confirms that the decreases of dust and sulfur dioxide industrial emission increase δ¹⁸O and δ¹³C values in glucose.