The objective of this study was to assess the removal of the endocrine disruptor 4-nonylphenol (NP) at a concentration of 1 mg L⁻¹ by ryegrass and radish during germination and growth. The decontamination process was evaluated in water only or in water containing two organic fractions, a soil humic acid (HA) and a river natural organic matter (NOM) at concentrations of 10 and 200 mg L⁻¹. The addition of these fractions aimed to simulate the organic content of real aqueous systems. At the end of germination and growth, residual NP was measured by chromatographic analysis. Also, NP phytotoxicity was evaluated during germination. In germination experiments, NP in water only was not toxic for ryegrass and radish which removed, respectively, 37 and 51 % of the initial NP added. In water added with HA or NOM at both doses, in general, NP did not influence or inhibited seed germination. Both doses of HA in water promoted the removal of NP by germinating seeds, whereas NOM exerted differentiated results in the two species as a function of the dose applied. After 2 days of growth, in all treatments both species almost completely removed NP and accumulated a very little fraction of product. This study demonstrated that both ryegrass and radish possess a relevant capacity to remove the endocrine disruptor NP from water also in the presence of different organic fractions, thus suggesting their use in the decontamination of real aquatic systems.

Utilization of industrial solid wastes for the treatment of wastewater from another industry could help environmental pollution abatement, in solving both solid waste disposal as well as liquid waste problems. Red mud (RM) is a waste product in the production of alumina and it poses serious pollution hazard. The present paper focuses on the possibility of utilization of RM as an adsorbent for removal of Remazol Brilliant Blue dye (RBB), a reactive dye from dye-contaminated water. Adsorption of RBB, from dye-contaminated water was studied by adsorption on powdered sulfuric acid-treated RM. The effect of initial dye concentration, contact time, initial pH, and adsorbent dosage were studied. Langmuir isotherm model has been found to represent the equilibrium data for RBB–RM adsorption system better than Freundlich model. The adsorption capacity of RM was found to be 27.8 mg dye/g of adsorbent at 40 °C. Thermodynamic analysis showed that adsorption of RBB on acid-treated RM is an endothermic reaction with ∆H ⁰ of 28.38 kJ/mol. The adsorption kinetics is represented by second-order kinetic model and the kinetic constant was estimated to be 0.0105 ± 0.005 g/mg min. Validity of intra-particle diffusion kinetic model suggested that among the mass transfer processes during the dye adsorption process, pore diffusion is the controlling step and not the film diffusion. The process can serve dual purposes of utilization of an industrial solid waste and the treatment of liquid waste.

The study focused on assessing the influence of rhamnolipids on the phytotoxicity of diesel oil-contaminated soil samples. Tests evaluating the seed germination and growth inhibition of four terrestrial plant species (alfalfa, sorghum, mustard and cuckooflower) were carried out at different rhamnolipid concentrations (ranging from 0 to 1.200 mg/kg of wet soil). The experiments were performed in soil samples with a different diesel oil content (ranging from 0 to 25 ml/kg of wet soil). It was observed that the sole presence of rhamnolipids may be phytotoxic at various levels, which is especially notable for sorghum (the germination index decreased to 41 %). The addition of rhamnolipids to diesel oil-contaminated soil samples contributed to a significant increase of their phytotoxicity. The most toxic effect was observed after a rhamnolipid-supplemented diesel oil biodegradation, carried out with the use of a hydrocarbon-degrading bacteria consortium. The supplemention of rhamnolipids (600 mg/kg of wet soil) resulted in a decrease of seed germination of all studied plant species and an inhibition of microbial activity, which was measured by the 2,3,5-triphenyltetrazolium chloride tests. These findings indicate that the presence of rhamnolipids may considerably increase the phytotoxicity of diesel oil. Therefore, their use at high concentrations, during in situ bioremediation processes, should be avoided in a terrestrial environment.

The objectives of this study were to characterize and map the spatial distribution of As, Cd, Cu, Pb, and Zn in topsoil at Rayong Province, a rapidly developing city, and to evaluate the associated health risks. A total of 130 soil samples were collected by a stratified random sampling technique. The soil samples were digested by HNO₃, HCl and H₂O₂, and heavy metals were determined by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Descriptive statistics and geostatistics were used to analyze the data, and the kriging method was used for data interpolation. The results show that the mean values of most heavy metals in the soil, except for As, were lower than Thailand's soil quality standard for habitat and agriculture purposes and the worldwide background level. Highly significant correlations were found for As/Cd, As/Cu, As/Pb, As/Zn, Cd/Cu, Cd/Pb, Cd/Zn, Cu/Pb, Cu/Zn, and Pb/Zn. In addition, most heavy metals showed significantly positive correlations with the reference element (Fe). Spherical, Gaussian and exponential models were selected for the semivariogram analysis of the heavy metals in the Rayong soil. As, Cd, Cu, and Pb were fitted with the spherical model, and Zn was fitted with the exponential model. The total hazard index (HIs) from the heavy metals in the Rayong soil found in both children and adults were in the order of As > Pb > Cu > Cd > Zn. The hazard index of As in the children was higher than 1. The major health risk areas are mainly located in the eastern part of the study area where the land is used for agriculture and in the southwestern areas where industrial activities take place.

Carbonic anhydrase (CA) has been immobilized on chitosan stabilized iron nanoparticles (CSIN) for the biomimetic carbonation reaction. CSIN was characterized using scanning electron microscope, energy dispersive X-ray, X-ray diffraction spectroscopy, and Fourier transform infrared analysis. The effect of various parameters such as pH, temperature and storage stability, on immobilized CA was investigated using a p-NPA assay. Kinetic parameters of immobilized and free CA (K ₘ and V ₘₐₓ values) were also evaluated. The K ₘ and V ₘₐₓ for immobilized CA was 1.727 mM and 1.189 μmol min⁻¹ ml⁻¹, respectively, whereas for free enzyme the K ₘ and V ₘₐₓ was 1.594 mM and 1.307 μmol min⁻¹ ml⁻¹, respectively. It was observed that the immobilized enzyme had longer storage stability and retained 50 % of its initial activity upto 30 days at room temperature. CA immobilized on CSIN has been used for hydration of CO₂, and the results were validated by using a gas chromatographic method. Proof of concept has been established for the biomimetic carbonation reaction. Immobilized CA show reasonably good CO₂ sequestration capacity of 21.55 mg of CaCO₃/mg of CA as compared to CO₂ sequestration capacity of 34.92 mg of CaCO₃/mg of CA for free CA respectively, under a limiting concentration of CO₂ (14.5 mg of CO₂/10 ml).

The effect of different humic fractions on polychlorinated biphenyl (PCB) contamination in soils was tested in the field by means of 53 soil samples from a high-altitude grassland plateau in the Italian Alps. Three humic fractions (humin, humic acids, and fulvic acids) were characterized in parallel by quantifying 12 PCB congeners to establish a direct relationship between PCB levels and humic fraction concentrations. Humin (the most hydrophobic fraction) appears to be the most closely correlated with the amount of PCBs in soil (R ²â€‰= 0.83), while fulvic acid shows the lowest correlation (R ²â€‰= 0.49). The idea of preferential sorption of hydrophobic compounds in the humin fraction is discussed, and the humin carbon content (f ₕᵤₘᵢₙC) is proposed as an improved parameter for evaluating the potential for POP accumulation in soils, replacing total organic carbon (f ₒc). Congener studies revealed that penta- and hexa-substituted-CBs show the optimal combination of physicochemical properties for equilibrating with the humin content in soil. Moreover, f ₕᵤₘᵢₙC/f ₒc is conceptually equivalent to the empirical coefficients used in predictive K ₛₐ equations. In our samples, the f ₕᵤₘᵢₙC/f ₒc was 0.55, a value in between the empirical coefficients proposed in the literature. In predictive equations, the use of f ₕᵤₘᵢₙC instead f ₒc avoids the necessity of using an empirical parameter for a ‘generic’ condition by introducing an experimental parameter (f ₕᵤₘᵢₙC) that takes into account local conditions (organic matter composition).

This paper analyses the influence of activated sludge technologies on the Particle Size Distribution (PSD) of urban wastewater treatment plants operating under real conditions. The activated sludge treatment systems selected for the analysis are the most widely used in wastewater treatment installations: (a) double step activated sludge, (b) medium load activated sludge, (c) prolonged aeration, and (d) membrane bioreactors The main quality parameters (suspended solids, turbidity, and COD) and PSD in the influent and effluent of each different activated sludge treatment were analyzed during 1 year. The PSD was fitted using the power law ([Formula: see text]) obtaining coefficients A and b to define the particle distribution. Mathematical correlations between this coefficients and the rest of parameters studied were found [Formula: see text]. The relation with the average particle size by mass was also found, ([Formula: see text]). Moreover, a relation between PSD and the particle elimination efficiency of the secondary treatment was study, ([Formula: see text]). Finally, the particulate matter nature was assessed by SEM-EDX. It can be concluded that membrane bioreactor is the technology that produces the best water quality effluent due to physic process of particle separation by ultrafiltration membrane technology.

Lead is a well-known pollutant with documented toxicity. Lead-containing weights used to balance motor vehicle wheels are regularly lost from vehicles and enter the environment. Lead weights deposited on roadways in the vicinity of Trenton, NJ were gathered and measured from February 2006 to January 2009. Measurements included loss of mass from specific weights exposed to traffic. Extrapolation of the results to the entire state suggests that approximately 12 tons per year of lead in the form of wheel weights are deposited on New Jersey roadways, and that approximately 40 kg of lead enters the environment in the form of small particles formed from the abrasion and grinding action of traffic on weights deposited on roadways. This quantity of small particles is much less than the approximately 60 tons per year of lead estimated by an earlier study to enter New Jersey in precipitation, some of which may result from the combustion of leaded aviation fuel. The quantity is also likely small compared with the fluxes of lead into the environment that still continue from leaded paint and with the residue of finely dispersed lead from historical uses of leaded gas in motor vehicles that remains in the environment. The quantity of lead released to the environment in the form of wheel weights appears likely to decline in the future because of legislation, voluntary phase-outs by manufacturers, and new trends in wheel technology

Elevated emissions of nitrogen oxides (NOx) in the Athabasca Oil Sands Region, Alberta and higher foliar nitrogen (N) concentrations in jack pine (Pinus banksiana) needles close to major emission sources has led to concerns that the surrounding boreal forest may become N-saturated. Despite these concerns, N deposition and impacts on upland forests in the region is poorly quantified. The objective of this study was to characterize N cycling in five plots representing the two dominant upland forest types (jack pine and trembling aspen, Populus tremuloides) close (<30 km) to the largest mining operations in the region, during a 2-year period. Despite the high level of NOx emissions, bulk throughfall and deposition measured at both study sites were surprisingly very low (<2 kg N ha−1 year−1). Internal N cycling was much greater in aspen stands; annual N input in litterfall was ten times greater, and net N mineralization rates were two to five times greater than in jack pine stands. Nitrogen use efficiency (NUE) was much greater in jack pine when calculated based on N litterfall indices, but not when N pools in biomass were considered. Despite differences in internal cycling among forest types, nitrate leaching from mineral soil in both forest types was negligible (<0.1 kg N ha−1 year−1) and patterns of 15N in roots, foliage, and mineral soil were typical of N-limited ecosystems, and both sites show no evidence of N saturation.