Laboratory experiments were carried out to study the uptake kinetics of selected metals and metalloids in the aquatic moss Fontinalis antipyretica. For this purpose, moss specimens from a clean site were exposed to concentrations of As, Hg, Sb, and Se ranging from 0.1 to 10,000 μg l−1, for incubation times of between 1 and 22 days, and the tissue concentrations of the metals in the moss specimens were then measured. Uptake kinetics followed different patterns in relation to exposure time, although the most common was Michaelis–Menten kinetics. On the contrary, the contamination factors followed very similar patterns in relation to the exposure concentrations in all cases, with a good fit to logarithmic equations. The bioconcentration factors tended to decrease as exposure concentration increased. The bioconcentration factors for Hg were extremely high, even at the lowest concentration in water and for the shortest incubation time, which implies that F. antipyretica has a high capacity to magnify Hg levels in water, which is an important characteristic in a good biomonitor. According to the time to reach equilibrium, the minimum exposure time recommended for use in active biomonitoring by means of transplants is very variable, although high levels of the elements, except Sb, were found in the moss tissues within a few days. We do not recommend the use of this moss species to biomonitor low concentrations of Sb in water. The differences in maximum contamination factors and lowest bioconcentration factors suggest that As and Se were the most toxic of the elements under study.

Nitrate contamination of groundwater represents a threat to human health. Many researchers have studied zerovalent iron as a mean to remediate nitrate contamination. However, the application of such method is limited by ammonium production. This work investigates the use of microscale iron particles in association with zeolitite, a natural material containing zeolite, to remove nitrate and ammonium from groundwater. The association of the two materials is shown to lower the nitrate concentration in both deionized water and groundwater under the limit suggested by the European Union and to significantly reduce the ammonium concentration. The method is potentially applicable in water filtration.

Nitrogenous air pollutants including nitrogen dioxide (NO₂), nitric acid (HNO₃), nitrate (NO ₃ ⁻ ), ammonia (NH₃), ammonium (NH ₄ ⁺ ), and nitrous acid (HONO) were characterized at an urban forested (UF) site in Hiroshima and at a suburban forested (SF) site in Fukuoka, western Japan, using an annular denuder system for 1 year from May 2006 to May 2007 to compare the concentrations and chemical species of atmospheric nitrogenous pollutants between UF and SF sites. The proximity of the urban area was reflected in higher NO₂ concentrations at the UF site than at the SF site. NO₂ was more oxidized at the SF site because it is farther from an urban area than the UF site, which was reflected in higher concentrations of HNO₃ at the SF site than the UF site. HNO₃ and acidic sulfate is neutralized by NH₃, existing as ammonium nitrate (NH₄NO₃) and ammonium sulfate [(NH₄)₂SO₄] at the UF site. At the SF site, acidic sulfate is neutralized by NH₃, existing as (NH₄)₂SO₄, but NH₄NO₃, had scarcely formed at the SF site. A much higher HONO concentration was observed at the UF site than at the SF site, especially in winter and spring at night, which could be explained by higher NO₂ concentrations at the UF site because of its proximity to an urban area and stagnant meteorological conditions. Atmospheric HONO determination was critical in evaluating the possibility of damage to trees in UF areas.

Arsenic occurs in the earth's crust in various chemical forms as a result of both natural and anthropogenic sources. Soil chemical extractions may help understand As availability, as well as the possibility of As entry into the food chain. Phytoextraction has been proposed as a technology for remediation of As-contaminated soils. The study was carried out to assess the bioavailability of As by extractants and to compare the performance of castor bean and sunflower for As removal from soils. Two soils were contaminated with Na2HAsO4.7H2O adding 35 and 150 mg As dm−3 soil. Arsenic availability was assessed using the following extractants: tri-distilled water, ammonium sulfate, ammonium phosphate, ammonium oxalate + oxalic acid, organic acids mixture, Mehlich-1, and United States Environmental Protection Agency 3051. The roots and shoots of 35-day-old plants were collected and dry matter yield as well as As concentration were determined. The accumulation of As in shoot was also calculated in order to evaluate the plants potential for As phytoextraction. The extractants tested were efficient to assess the concentration of available As in soil. Addition of As to the soils did not cause severe toxicity in plants, although the dose 150 mg As dm−3 soil decreased shoot and root yield in both species. Castor bean was less sensitive to As than sunflower, but none of the species had hyperaccumulation characteristics. These species can be used for revegetation of areas contaminated with As up to safe limit of 150 mg As dm−3 soil, as proposed by CONAMA for industrial areas in Brazil.

Anionic surfactants, the earliest and the most common surfactants in detergent and cosmetic product formulations contribute significantly to the pollution profile of the ecosystem. Linear alkylbenzene sulfonates (LAS), a major chemical constituent of detergents, forms an imperative group of anionic surfactants. Bioremediation of LAS by conventional processes such as activated sludge is ineffective due to the low kinetics of degradation by unsuitable organisms and foam production. Hence this study was focused on isolating and characterizing indigenous LAS-degrading bacteria from soil. Twenty different LAS-degrading bacteria were isolated from detergent-contaminated soil by enrichment culture technique and degradation efficiency was assessed by Methylene Blue Active Substances (MBAS) assay and by reverse-phase high-performance liquid chromatography (HPLC) analysis. The most efficient LAS-degrading isolates, L9 (81.33 ± 0.7) and L12 (81.81 ± 0.8), were selected and identified as Pseudomonas nitroreducens (MTCC 10463) and Pseudomonas aeruginosa (MTCC 10462). The 16S rDNA sequences of the isolates were deposited in NCBI GenBank under the accession numbers HQ 271083 (L9) and HQ 271084 (L12). The isolates were capable of degrading 0.05 g/l LAS at 25 °C and pH 7.0–7.5. Presence of a solid support caused biofilm formation which in turn enhanced LAS degradation. The isolates tend to display diauxic growth with alternate carbon source such as dextrose. These isolates also have the capability to degrade other xenobiotics like hydrocarbons and pesticides. Since xenobiotic pollutants in nature occur as a mixture of compounds rather than single pollutants, the potential of these two indigenous LAS-degrading isolates to degrade multiple xenobiotics gains relevance.

The effect of plant growth-promoting bacteria inoculation on Helianthus annuus growth and copper (Cu) uptake was investigated. For this, the strains CC22, CC24, CC30, and CC33 previously isolated from heavy metal- and hydrocarbon-polluted soil were selected for study. These strains were characterized on the basis of their 16S rDNA sequences and identified as Pseudomonas putida CC22, Enterobacter sakazakii CC24, Acinetobacter sp. CC30, and Acinetobacter sp. CC33. Strains were able to synthesize indole, solubilize phosphorus, and produce siderophores in vitro, which are proper characteristics of plant growth-promoting (PGP) bacteria. Bacteria were also able to bioaccumulate Cu(II), and most of them could use aromatic hydrocarbons as a sole carbon source. Furthermore, Acinetobacter sp. CC33 exhibited the greatest extent of Cu(II) accumulation, and CC30 the widest range for degrading hydrocarbons. Acinetobacter sp. CC30 was selected for pot experiments on the basis of its plant growth-promoting properties. Inoculation with CC30 significantly increased the plant biomass (dry weight and length of root and shoot) and improved the photosynthetic pigment content in non- and Cu-contaminated soil (p < 0.05). Additionally, plant Cu uptake was improved by CC30 inoculation showing a significantly enhanced root Cu content (p < 0.05). Our findings evidenced that the strain CC30 protected the plant against the deleterious effect of Cu contamination and improved the Cu extraction by plant, hence concluding that its inoculation represents an alternative to improve phytoremediation process of heavy metals, particularly Cu, in contaminated environments.

The paper presents results of a long-term investigations of tritium activity concentrations in precipitation and radiocesium activity concentrations in ground level air in Belgrade, Serbia. Samples were collected at three locations in Belgrade (Meteorological Station of Belgrade MS at Zeleno Brdo (ZB), Meteorological Station MS Usek (USEK), and Vinča Institute of Nuclear Sciences (VINS)). Presented data cover the period 1985–1997. Significantly higher tritium levels were measured in samples in VINS compared with off-site location, while the impact of research reactor for 137Cs was not detected. It was found that the value of the symmetrical index n is higher for VINS in case of tritium, compared to other locations, which is in accordance with the fact that the highest average monthly concentrations of tritium were obtained in the samples from the cited place. Although the highest value of index n in case of 137Cs was also obtained for VINS, average monthly concentrations of 137Cs in ground level air for this location were the lowest. The 137Cs concentration in the ground level air is described by a kinetic equation of the first order and provides a good description of the time changes in these concentrations.

Natural clinoptilolite was modified with hexadecyltrimethylammonium chloride, a cationic surfactant, and then melt-mixed with polypropylene hollow fibres to produce polymer composites with adsorptive properties. The performance of the fabricated composites was evaluated by optimizing experimental parameters such as surfactant loading, contact time, pH and initial concentration for the adsorptive removal of 2,4,6-trichlorophenol (TCP) and ortho-nitrophenol (o-NP). Based on the fourier transmission infrared spectra and scanning electron microscopy micrographs of as-received and surfactant-modified clinoptilolite, the modification of natural clinoptilolite was attained. The composites showed enhanced adsorption capability for TCP over o-NP with removal efficiencies of 84% and 46%. Loading the clinoptilolite with surfactant concentrations beyond 8 mM reduced the adsorption capacity. The removal of TCP and o-NP was found to depend critically on the pH of the solution, and the optimum ranges were 4–6 and 2–6 for compounds, respectively. The adsorption dynamics were determined with first- and second-order kinetics models, and the adsorption system for TCP and o-NP followed the first-order kinetics. Adsorption isotherm analysis revealed that the adsorption equilibrium data obeyed/fit the Freundlich isotherm.

Hydrophobic organic compounds are common in the environment, especially in water bodies like rivers and lakes. Generally, due to their physico-chemical characteristics, mainly to hydrophobicity, these compounds are adsorbed by suspended material or other compartments which provide compatibility. Thus, compounds such as polycyclic aromatic hydrocarbons (PAHs) are rapidly adsorbed onto suspended material or even naturally occurring biofilms in water bodies. Biofilms can be defined as complex structures with cells and aggregates of cells. The extracellular polymers present empty spaces that can be filled by water. The biofilm is a sessile microbial community with several kinds of organisms such as bacteria, protozoa, fungi, algae, and extracellular polymeric substances, which may be found on almost any surface exposed to water. Here, biofilms were used to monitor the presence of PAHs in the Barigui River in Curitiba, Brazil. For the measurements and collection of representative microcoenoses, a biofilm sampling device was designed consisting of six glass plates installed in an open polyvinyl chloride pipe of 30 cm diameter and 60 cm length. The sampling device was exposed in the Barigui River for 2 weeks campaigns. The formed biofilm was treated and chemical analysis was performed for PAHs determination. The results showed that biofilms can trap most of the PAHs, especially those with high K ₒw values (octanol–water partition coefficient). Four campaigns were conducted. The total PAHs concentration ranged from 11,204.34 ± 560.12 to 45,846.90 ± 2,290.45 ng/g. According to the isomers ratio, the main source of PAHs in the first and second campaign was of pyrolytic origin, in other words, the PAHs were by-products from burning of light-refined oil products (gasoline and diesel oil). Meanwhile, the other campaigns revealed that the main source is of petrogenic origin. However, the possibility of both sources is not discarded considering the scenario studied and the records of sediments samples. Most of the investigations carried out focused on the loading of river sediments and suspended solids, but the biofilms might detect the amount that could be taken up by benthic organisms, for instance.

A laboratory study was conducted to assess the feasibility of remediating diesel-contaminated soils using sodium persulfate (SPS) oxidation under an alkaline pH. Lime (CaO) and sodium hydroxide (NaOH) were used as the alkaline sources, and various factors, including temperature, reaction time and concentration level, were investigated. Moreover, the combined usage of hydrogen peroxide (HP) and SPS in the presence or absence of NaOH was also studied. It was found that lime hydration resulted in rapid increases in pH (>12) and temperature (75 °C maximum) at a CaO/H₂O mass ratio of 3/20. In the NaOH or CaO/SPS system, the maximum diesel degradation achieved was approximately 30 %. It was observed that using a larger amount of alkaline increased SPS decomposition and had almost no effect on diesel degradation. Limited solubilization of contaminants may have inhibited the effectiveness of alkaline-activated persulfate oxidation during the aqueous phase and hence resulted in incomplete diesel degradation. The highest rate of diesel degradation (i.e., 56 % in 7 days) was achieved using the dual oxidation system, in which a HP/SPS molar ratio of 3.3/0.5 was used. An aggressive oxidation process, coupled with HP, may enhance desorption of diesel from soils and allow oxidation to occur during the aqueous phase.