Hexavalent chromium is a heavy metal used in a variety of industrial applications which is highly toxic to humans, animals, plants and microorganisms. Moreover, it is a well-established human carcinogen by the inhalation route of exposure and a possible human carcinogen by the oral route of exposure. Therefore, it should be removed from contaminated waters. Its reduction to trivalent chromium can be beneficial because a more mobile and more toxic chromium species is converted to a less mobile and less toxic form. During the last two decades, there has been important interest in using zero-valent iron (ZVI) as a Cr(VI)-reducing agent. A considerable volume of research has been carried out in order to investigate the mechanism and kinetics of Cr(VI) reduction with ZVI, as well as the influence of various parameters controlling the reduction efficiency. Therefore, the purpose of this review was to provide updated information regarding the developments and innovative approaches in the use of ZVI for the treatment of Cr(VI)-polluted waters.

Prediction of the sorption behavior of environmental pollutants is of utmost importance within the framework of risk assessments. In this work two approaches are presented with the aim to describe sorption of aromatic substances to geosorbents. First, analytical solutions of kinetic models were fitted to experimental data of batch sorption experiments with aniline and 1-naphthylamine onto animal manure-treated soil and the soil mineral montmorillonite. The models, accounting for equilibrium and nonequilibrium sorption coupled to transformation and/or irreversible sorption processes, could well reproduce the concentration course of the sorbates. Results suggest that the amounts transformed/degraded and irreversibly bound were higher for the soil than for the clay mineral. In the second part, quantum chemical calculations were performed on aniline and 1-naphthylamine interacting with acetic acid, acetamide, imidazole, and phenol as models of functional groups present in humic substances. Molecular modeling showed that formation of hydrogen bonds is the dominating binding mechanism in all modeled complexes, which are energetically very similar between aniline and 1-naphthylamine.

Mixed microbial culture was isolated from heavy metal-contaminated ground soils located inside iron, vinyl and cement factory area. Isolated mixed microbial culture was used for the heavy metal ions (Fe²⁺, Cu²⁺, Ni²⁺ and Zn²⁺) removal process in horizontal rotating tubular bioreactor (HRTB). In this research, the effect of bioreactor process parameters on the bioprocess dynamics in the HRTB was studied. Results of this research have shown that profiles of heavy metals concentration were gradually reduced along HRTB at all combinations of bioreactor process parameters [inflow rates (0.5-2.0 L h⁻¹) and rotation speed (5-30 min⁻¹)]. Hydrodynamic conditions and biomass sorption capacity have main impact on the metal ions removal efficiency that was varied in the range of 38.1% to 95.5%. Notable pH gradient (cca 0.7 pH unit) along the HRTB was only observed at the inflow rate of 2.0 L h⁻¹. On the basis of obtained results, it is clear that medium inflow rate (F) has higher impact on the heavy metal removal process than bioreactor rotation speed (n) due to the fact that increase of inflow rate was related to the reduction of equilibrium time for all examined metal ions. Furthermore, equilibrium times for all metal ions are significantly shorter than medium residence times at all examined combinations of bioreactor process parameters. The main impact on the biofilm sorption capacity has covalent index of metal ions and biofilm volumetric density. The sorption capacity of suspended microbial biomass is closely related to its concentration. Results of this research have also shown that the removal of heavy metals ion can be successfully conducted in an HRTB as a one-step process.

To simulate the atmospheric fate of air pollutants, it is first necessary to know the emission rates that describe the release of pollutants into ambient air. For benzo(a)pyrene emission data are currently only available as yearly bulk emissions while the simulation models typically require temporally resolved emissions (e.g. hourly). Because residential heating is by far the most important source for benzo(a)pyrene, we developed a method to temporally disaggregate these bulk emission data using the linear dependency of benzo(a)pyrene emission rates stemming from residential combustion on ambient temperature. The resulting time-dependent hourly emission rates have been used in a chemical transport model to simulate concentrations and deposition fluxes of benzo(a)pyrene in the year 2000. The same simulations were repeated with constant emission rates and emission rates that varied only seasonally. By comparing the modeling results of the three emission cases with monthly measurements of air concentrations, the characteristic and the benefit of our disaggregation approach is illustrated. The simulations with disaggregated emissions fitted best to the measurements. At the same time the spatial distribution as well as the yearly total deposition was notably different with each emission case even though the yearly total emissions were kept constant.

Technosols are anthropogenic soils that may be strongly impacted by heavy metal deposition, which have not yet been described in Antarctica. In this paper, we present a chemical study of what is supposedly the oldest manmade soil from Antarctic Peninsula, developed in the vicinity of Trinity House and Nordenskjold Hut at Hope Bay. Chemical and morphological soil attributes indicate that a former ornithogenic site (penguin rookery) was further subjected to human disturbance, following local exploration since 1903. We detected very high amounts of heavy metals such as Cd, Cu, Pb, and Zn. For the most impacted site, pseudototal concentrations of these elements reach 47, 2,082, 19,381, and 5,225 mg kg−1, respectively. Enrichment factors were calculated using Zr as reference element, and high values were found for these contaminated sites, qualifying some of them as extremely polluted. Also, both the mobilizable and mobile fraction of Cd and Pb indicate the need of intervention in the affected area. These findings are all consistent with the human impacts and strong contamination. Strong positive correlation between the pseudototal concentrations of Cd, Cu, Mn, Ni, Pb, and Zn indicates a similar source of pollution. These soils may represent the oldest Technosols in Antarctic Continent.

INTRODUCTION: In order to identify a potential surrogate of planktonic ciliate communities for marine bioassessments and evaluating biological conservations, the different taxonomic/numerical resolutions and taxa as surrogates were studied in Jiaozhou Bay, northern China during a 1-year cycle (June 2007–May 2008). MATERIALS AND METHODS: Samples were collected biweekly from a depth of 1 m at each of five sites. A range of physicochemical parameters were also measured in order to determine water quality. RESULTS: The genus- and family-level resolutions maintained sufficient information to evaluate the ecological patterns of the ciliate communities in response to environmental status. The non-loricate oligotrichous ciliate assemblages in both abundance and occurrence may be used as a surrogate of planktonic ciliate communities. Heavy data transformations were an optimal strategy for the species level of planktonic ciliates, while mild data transformations were for the higher. The ordination patterns based on species biomass, occurrence, and biomass/abundance ratio matrices were significantly consistent with that of species abundance data. CONCLUSION: The results suggest that the use of simplifications at both taxonomic and numerical resolutions are time-efficient and would allow improving sampling strategies of large spatial/temporal scale monitoring programs and biological conservation researches in the marine ecosystem with a relative paucity of scientists.

Introduction The application of response surface methodology is presented for optimizing the removal of U ions from aqueous solutions using Padina sp., a brown marine algal biomass. Methods Box-Wilson central composite design was employed to assess individual and interactive effects of the four main parameters (pH and initial uranium concentration in solutions, contact time and temperature) on uranium uptake. Results and discussion Response surface analysis showed that the data were adequately fitted to second-order polynomial model. Analysis of variance showed a high coefficient of determination value (R ² = 0.9746) and satisfactory second-order regression model was derived. Conclusion The optimum pH and initial uranium concentration in solutions, contact time and temperature were found to be 4.07, 778.48 mg/l, 74.31 min, and 37.47°C, respectively. Maximized uranium uptake was predicted and experimentally validated. The equilibrium data for biosorption of U onto the Padina sp. were well represented by the Langmuir isotherm, giving maximum monolayer adsorption capacity as high as 376.73 mg/g.

Introduction In this study, olive tree leaves, collected from 50 sampling sites throughout the Province of Aydın, Turkey, were used to estimate level of pollution by measuring Al, As, B, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, and Zn concentrations and calculating pollution factor (PF) values. Materials and methods After sample preparation, collected leaves were microwave digested, and extracts were analyzed by an inductively coupled plasma-mass spectrometer. Results and discussion The maximum PF values were ≥10 for a number of elements ranging from 11-13 (Al, As, Cr, Fe, Mn, Ni) to >100 for Cu, Li, and Na. Urban-rural and roadside-nonroadside concentration comparisons showed that some of the elements (As, Cu, and Pb) were at significantly higher levels on urban and/or roadside sampling sites. Summary and conclusion Correlations and factor analysis showed that there may be common sources for some elements, which included several soil types and anthropogenic activities. Based on the results of the statistical source apportionment, possible sources were narrowed down with help of the constructed elemental concentration maps. In conclusion, utilization of olive tree leaves for biomonitoring and assessment of environmental pollution was shown to be possible in the Mediterranean region where they are indigenous and cultivated.

Objective The purpose of the study was to investigate natural radionuclide uptake and allocation by trees. Materials and methods Samples from six Scots pines (P. sylvestris), six Norway spruces (Picea abies) and one sycamore maple (Acer pseudoplatanus) tree, growing on the Boršt uranium mill tailings waste pile in Slovenia were collected. ²³⁸U, ²³⁰Th, ²²⁶Ra and ²¹⁰Pb activity concentrations in wood, shoots and 1-year-old needles or leaves were determined. Particular radionuclides were separated from the samples by appropriate radiochemical procedures and their activity concentrations measured with an alpha spectrometry system. In addition, concentration ratios for different plant parts were calculated. Results and conclusions Results showed that for all radionuclides, the highest activity concentrations were found in foliage, followed by shoots and wood. The activity concentrations in trees were from 0.01 to 5.4 Bq kg⁻¹ for ²³⁸U, 0.03-11.3 Bq kg⁻¹ for ²³⁰Th, 2.7-2,728 Bq kg⁻¹ for ²²⁶Ra and 5.1-321 Bq kg⁻¹ for ²¹⁰Pb. All activity concentrations were calculated on dry weight basis. The calculated concentration ratios were from 1.05E-5 to 5.39E-3 for ²³⁸U, 7.65E-6-2.88E-3 for ²³⁰Th, 3.10E-4-3.16E-1 for ²²⁶Ra and 6.70E-4-4.22E-2 for ²¹⁰Pb.

Background, aim, and scope The aim of the present study was to evaluate the distribution of petroleum hydrocarbons in ten commercial fish species and water samples in three estuaries along Tamilnadu coast, Bay of Bengal, India. Materials and methods Fish and water samples collected from Tamilnadu coast, India, were extracted and analyzed for petroleum hydrocarbons by ultraviolet fluorescence (UVF) spectroscopy. Results The petroleum hydrocarbon concentration (PHC) in coastal waters and fish species varied between 2.28 and 14.02 μg/l and 0.52 and 2.05 μg/g, respectively. The highest PHC concentration was obtained in Uppanar estuarine waters (14.02 ± 0.83) and the lowest was observed in Vellar estuarine waters (2.28 ± 0.25). Discussion Among the ten fish species, Sardinella longiceps have high PHC concentration from all the locations. This study suggests that S. longiceps can be used as a good biological indicator for petroleum hydrocarbon pollution in water. Conclusions The concentration of petroleum hydrocarbons in coastal waters along Tamilnadu coast is markedly higher than that in the background, but there is no evidence for its increase in fish of this region. From a public health point, petroleum hydrocarbon residue levels in all fish samples analyzed in this study are considerably lower than the hazardous levels. Recommendations and perspectives At present, as Tamilnadu coastal area is in a rapid development stage of new harbour, chemical industries, power plants, oil exploration and other large-scale industries, further assessment of petroleum hydrocarbons and the various hydrodynamic conditions acting in the region are to be studied in detail and continuous pollution monitoring studies should be conducted for improving the aquatic environment. The results will also be useful for pollution monitoring program along the coastal region and also to check the levels of petroleum hydrocarbons.