Cyanide is found as free cyanide and metal–cyanide complexes in metal finishing rinse wastewaters. Experiments were performed to seek removal of cyanide in Ni(II)–cyanide and Ni(II)–cyanide–ethylenediaminetetraacetate (EDTA) solutions by the environmentally friendly oxidant, ferrate(VI) (FeO4 2−, Fe(VI)) as a function of pH (8.0–11.0). Incomplete removal of cyanide in Ni(II)–cyanide solutions (≤60%) was observed at the studied pH range. However, cyanide removal efficiency approached to 100% in Ni(II)–cyanide–EDTA solutions. Formation of Ni(II)–cyanide and Ni(II)–EDTA complexes and relative rates of the reactions of Fe(VI) with various species (water, cyanide, Ni(II)–cyanide, and EDTA) present in solutions were responsible for the variation in removal efficiencies in mixtures at various pH. The oxidation of cyanide by Fe(VI) produced cyanate. Tests using electroplating rinse wastewaters demonstrated that Fe(VI) was highly effective in removing cyanide.

The levels of radioactive contamination by artificial radiocesium (137Cs) were evaluated in sediments and the commonest species of water plants. Specimens were collected from a range of biotopes along the Pinios River and its tributaries, during the years 1998 and 2010. The 137Cs concentrations within the above period clearly indicate that this radionuclide still decrease in the River Pinios. A marked decrease is also observed in comparison to our previous results in 1993. 137Cs concentration activities in the sediment are higher than in the plant material. In general, roots showed greater 137Cs concentration than leaves, while stems showed the lowest concentration. Significant differences in 137Cs concentrations were found among different species growing under similar environmental conditions. 137Cs content in collected aquatic plants was in the descending order: Ceratophyllum demersum L. > Myriophyllum spicatum L. > Paspalum pasalodes Scribner > Cladophora glomerata L. > Cyperus longus L. > Potamogeton nodosus Poiret. A comparison of the studied stations indicated that the southwest side of Thessalia plain, where the first two initial sampling stations of the Pinios River and the tributaries Enipeas and Kalentzis are situated, was highly contaminated. Low 137Cs concentrations were observed in the Titarisios tributary, originated from the northeast part of Thessalia plain, behind Mt. Olympus and the last sampling stations of the Pinios River.

Fluid catalytic cracking unit is of great importance in petroleum refining industries as it treats heavy fractions from various process units to produce light ends (valuable products). FCC unit feedstock consists of heavy hydrocarbon with high sulfur contents, and the catalyst in use is zeolite impregnated with rare earth metals, i.e., lanthanum and cerium. Catalytic cracking reaction takes place at elevated temperature in fluidized bed reactor generating sulfur-contaminated coke on the catalyst with large quantity of attrited catalyst fines. In the regenerator, coke is completely burnt producing SO2, PM emissions. The impact of the FCC unit is assessed in the immediate neighborhood of the refinery. Year-long emission inventories for both SO2 and PM have been prepared for one of the major petroleum refining industry in Kuwait. The corresponding comprehensive meteorological data are obtained and preprocessed using Aermet (Aermod preprocessor). US EPA approved dispersion model, Aermod, is used to predict ground level concentrations of both pollutants in the selected study area. Model output is validated with measured values at discrete receptors, and an extensive parametric study has been conducted using three scenarios, stack diameter, stack height, and emission rate. It is noticed that stack diameter has no effect on ground level concentration, as stack exit velocity is a function of stack diameter. With the increase in stack height, the predicted concentrations decrease showing an inverse relation. The influence of the emission rate is linearly related to the computed ground level concentrations.

Nitrogen dioxide is an important gaseous air pollutant. It plays a major role in atmospheric chemistry, particularly in the formation of secondary air pollutants, and contributes to environmental acidification. A comprehensive assessment of NO2 levels in the atmosphere is required for developing effective strategies for control of air pollution and air quality improvement. Air pollution is a serious problem in all major cities of Pakistan and needs to be addressed to minimize detrimental effects on human health and urban vegetation. In this research, we focused on the monitoring of NO2 levels in the urban environment of Rawalpindi city. Because of the lack of expensive continuous sampling devices and to get a good spatial coverage of the NO2 concentrations in the study area, NO2 passive samplers were exposed at 42 different sites within the city limits of Rawalpindi from January to December, 2008. Samplers were exchanged every 10 days and the associated meteorological conditions like temperature, wind speed, rainfall and relative humidity were also monitored. The average NO2 concentration was found to be 27.46 ± 0.32 ppb. The highest values of NO2 were measured near to main roads and educational institutions due to intense flow of road vehicles. Moreover, the study showed that the values obtained for NO2 for all sampling points exceeded the annual limit value set by World Health Organization. So, this is very important to take different steps to control this before it becomes a serious hazard for people living in those areas.

The influence of a change from daily to weekly sampling of bulk precipitation on the obtained deposition values was studied with parallel sampling for 8 months at the station of Virolahti in 2004. Due to dry deposition, the deposition values of the whole period were found to be 5–70% higher from weekly sampling than from daily sampling, the biggest difference being for K+, Ca2+, Mg+ and Na+. The collection efficiencies of the summer sampler and the winter sampler compared to the standard rain gauge were studied from daily sampling in 1991–2003 and weekly sampling in 2004–2008. The performance was best in summer and in winter with rain samples (median value 85–88%), while the median value for daily snow samples was 72%. In winter, the total sum of precipitation collected in the daily sampler and the weekly sampler was 78% and 69%, respectively. The deficit in the weekly sampler in winter was concluded to be due to evaporation, while from the summer sampler no evaporation seemed to occur. Use of the precipitation amount measured by the standard rain gauge when calculating annual precipitation-weighted mean values gave higher mean concentrations than the use of the precipitation measured by the deposition sampler itself, the biggest difference of 8–11% being in the sea-salt ions Cl−, Mg+ and Na+. It was concluded that the concentration and deposition values measured by daily and weekly bulk sampling are incompatible, and should not be combined into the same time series.

This study evaluated the copper ion adsorption capacity of sugarcane bagasse in natura and chemically modified with citric acid and sodium hydroxide. Adsorption analyses in batch system were carried out in function of contact time with the adsorbent and adsorbate concentration. Flame atomic absorption spectrometry was used to determine the copper concentrations. Adsorption experimental data were fitted to Langmuir and Freundlich linear models, and the maximum adsorption capacity was estimated for copper ions in function of modifications. The chemical modifications were confirmed at 1,730 cm−1 peak in infrared spectra, referring to the carboxylate groups. The required time for the adsorption to reach equilibrium was 24 h and the kinetics follows the behavior described by the pseudo-second order equation. Besides, a significant improvement of the copper adsorption has been observed after the bagasse treatment, where the maximum adsorption capacity was 31.53 mg g−1 for copper using modified bagasse with nitric acid according to Langmuir isotherm linear model. The high uptake of copper ions from aqueous medium verified by chemically modified sugarcane bagasse makes this material an attractive alternative for effluent treatment and avoids environmental contamination.

Modeling reactive transport with chemical equilibrium reactions requires solution of coupled partial differential and algebraic equations. In this work, two formulations are developed to combine the method of lines (MOL) with the global implicit approach. The first formulation has a non-conservative form and leads to a nonlinear system of ordinary differential equations with a reduced number of unknowns. The second formulation presents better conservation properties but leads to a nonlinear system of differential algebraic equations with a large number of unknowns. In both formulations, the resulting systems are integrated in time using the DLSODIS time solver which adapts both the order of the time integration and the time step size to provide the necessary accuracy. Numerical experiments show that higher-order time integration is effective for solving the non-conservative formulation and point out the high benefit of the MOL for solving reactive transport problems.

Genetic variation and genetic structure of black spruce (Picea mariana L.) populations growing in wet land (lowlands) and dry lands (uplands) with different levels of metal contaminations were analyzed using ISSR. Polymorphic loci (P%) ranged from 65% to 90% with a mean of 75%. Nei’s gene diversity (h) varied from 0.264 to 0.359 with a mean of 0.310, and Shannon’s index (I) ranged from 0.381 to 0.524 with a mean of 0.449. The level of genetic variation was higher in populations from wet lands than those from dry lands. Variation within populations accounts for most of total genetic variation. The genetic distance among the black spruce (P. mariana) populations ranged from 0.171 to 0.351. The present study indicates that genetic variation and long-term exposure to metals (more than 30 years) are not associated. Cytological analysis of black spruce seeds from metal-contaminated and -uncontaminated areas showed normal mitotic behavior during prophase, metaphase, anaphase, and telophase.

Reducing conditions of submerged soils were simulated in laboratory experiments by keeping various soil samples from urban areas under an aqueous solution in sealed flasks for several lengths of time. A polluted soil from a different origin was also included for comparison. Metals dissolved at various times were determined, and availability and bio-accessibility of metals present in the solid phase were estimated. Although significant amounts of Fe and Mn were dissolved, other metals were released to the solution to a much lesser extent. This effect is attributed to the greater solubility of reduced forms of Fe and Mn, and the small amounts of other metals dissolved during water-logging were related with metals retained by, or occluded in, the reduced Fe or Mn compounds. The amounts of available and bio-accessible metals remaining in the solid phase were significantly increased by water-logging, particularly the latter form. Such increase of metal mobility is likely to favour metal leaching to the water table as well as the transfer of potentially toxic elements to humans during recreational activities.