Plant toxicity and chemical removal tests were conducted to investigate the remediation ability of grasses with respect to volatile organic contaminants (VOCs) in contaminated soil and air. Eastern gamagrass (Tripsacum dactyloides) and annual ryegrass (Lolium rigidum) were exposed to artificially contaminated soil or air containing a mixture of 1,1,1-trichloroethane (TCA), trichloroethylene (TCE), and tetrachloroethylene (PCE) under controlled laboratory conditions. The results showed that the grasses are more severely affected in hydroponics than potted soil contaminated with a mixture of these contaminants. It was observed from the results that more contaminants were detected in the shoot and root of plants grown in a closed system with contaminated air than in an open system with contaminated soil. It is suggested from the results that grasses can be used for purification of VOCs from contaminated air especially in a closed system, but the purification effects are likely to be low. The results also suggested that the concentration level of VOCs in shoot, root, and soil could be used as contamination indicator at contaminated sites.

The selective recovery of Cd from simulated spent nickel–cadmium battery solutions was achieved using a Cd working electrode in a laboratory cell with a three-electrode arrangement in hydrochloric, nitric, and sulfuric acids. The latter was selected for further study of the recovery step. Nitrate media were found to be unsuitable for Cd recovery since nitrates are reduced at the required deposition potentials. Cd(II) deposition on Cd electrodes is favored in sulfate or chloride media since it occurs at a potential some 200 mV less negative than that of Ni(II). A good percent Cd recovery (>90%) with high selectivity (approximately 0% Ni) and a reasonably high current efficiency (>80%) can be achieved under appropriate conditions. The irreversible nature of Ni(II) reduction provides the necessary framework to achieve such a selective separation.

An intensive survey of mercury speciation was performed at a site on the Upper St. Lawrence River near Cornwall, Ontario, Canada with a history mercury contamination in sediments. Surface sediments were collected every 1.50 h. Total mercury (Hgtotal), methylmercury (MeHg), organic carbon, inorganic and organic sulphur were determined in the solid fraction. Dissolved Hgtotal, MeHg and dissolved organic carbon (DOC) were measured in pore waters. Concentrations of Hgtotal in the upper layers (first 5 cm) were high, ranging from 1.42 to 25.8 nmol g-¹ in solids and from 125 to 449 pM in pore waters. MeHg levels were also high, ranging from 4.34 to 34.1 pmol g-¹ in solids and from 40 to 96 pM in pore waters. This amounts to up to 1.4% of Hgtotal present as MeHg in solids and 64% in pore waters. A daily pattern for Hgtotal was observed in the solid fraction. The MeHg distribution in solids and pore waters was not correlated with Hgtotal or DOC, suggesting that the concentrations of MeHg are probably more influenced by the relative rates of methylation/demethylation reactions in the sediment-water interface. Acid volatile sulphide levels and DOC were inversely correlated with organic sulphur (Sorg) levels suggesting that both parameters are involved in the rapid production of Sorg. A positive correlation was also observed between Hgtotal and Sorg in solids (R = 0.87, p < 0.01) illustrating the importance of organic sulphur in the retention and distribution of Hg in the solid fraction of the sediments. The results suggest that variations of Hgtotal concentrations in Upper St. Lawrence River surface sediments were strongly influenced by the formation/deposition/retention of organic sulphur compounds in the sediment-water interface.

Nitrates in concentrated brines can be electrochemically reduced in the cathodic chamber of a split-cell electrochemical reactor with formation of ammonium (and small amounts of nitrite). Fortunately, ammonium may be electrochemically oxidized to nitrogen gas in the anodic reaction chamber if a coupled sequential process is used. The presence of chloride in the brine waste is an important consideration in oxidative electrochemical processes, however, because it cycles through oxidized and reduced states at the electrode surfaces and in the bulk solution. Electrochemical oxidation converts chloride ions to “active chlorine” species with additional oxidizing capability (chlorine, hypochlorous acid and hypochlorite - essentially bleach), as well as to chlorates, depending on the reaction conditions. The production of these active species improves treatment performance in the ammonium oxidation phase since oxidation is no longer limited to the electrode surface. However, the process must be engineered to minimize loss of process efficiency due to parasitic side reactions (chloramines and chlorate). In this study, two-stage batch electrolysis was conducted using a three-electrode (copper anode, platinum-coated titanium cathode, silver/silver chloride reference) electrochemical cell, with the anodic and cathodic chambers separated by a Nafion 117 membrane. Treatment of nitrate and ammonium was tested with and without the presence of chloride in the waste. No significant difference was observed in cathodic nitrate reduction with chloride present or absent. However, the presence of chloride in the solution favored overall soluble nitrogen elimination upon oxidation. Increasing applied current increased production of undesirable byproducts (especially chlorate).

The type and amount of indoor air pollutants affects the comfort and quality of indoor environments. Therefore, indoor air quality is an important issue with different social, economic, and health aspects because people in developing countries spend most of their time indoors being exposed to different kinds of indoor pollutants. The indoor air quality can be assessed empirically by measuring the pollutant concentrations or can be predicted by means of mathematical models. An indoor aerosol model describes the dynamic behavior of indoor air pollutants. The basic concept of indoor air models is the mass-balance-conservation where several factors that govern the indoor particle concentrations can be described. These factors may include direct emissions from indoor sources, outdoor aerosol particles penetrating indoors as a result of the ventilation and filtration processes, deposition onto indoor surfaces, and removal from indoor air by means of ventilation. Here we present principles of indoor aerosol models and we also give examples of different kind of models.

Soil translocation for recultivation of soil removed from construction sites and for the preparation of refilled lysimeters inevitably involves disturbance of soil structure, and, if intermediate storage is included, also drying and rewetting of the soil. We report on an experiment with model forest ecosystems, where uncontaminated forest subsoils were covered with non-contaminated or freshly heavy metal (mainly Zn and Cu) contaminated topsoil in large lysimeters. Monitoring of the chemical composition of the drainage water revealed two distinct soil conditioning phases. During an initial phase of about a year strongly elevated nitrate and sulfate concentrations occurred that were attributed to a mineralisation flush caused by the increased accessability of mineralisable nitrogen and sulfur in destroyed aggregates. These effects were significantly larger in lysimeters with calcareous subsoil than in those with acidic subsoil. The second phase was characterised by a gradual decrease in dissolved organic carbon and sulfate concentrations, in particular in the acidic subsoil. This decrease may be attributed to the depletion of pools made accessible during aggregate destruction or the formation of new aggregates. These chemical changes had only little effects on the concentrations of copper and zinc in the drainage water. Based on our results, it can be concluded that large refilled lysimeters can be used for many purposes without risk of compromised results, if a conditioning phase of about 1 year with sufficiently moist soil conditions is respected. Nevertheless, gradual changes in soil chemical characteristics still occur after this initial phase. Implications for the recultivation of sites using relocated soils are discussed.

In a risk assessment study the environmental fate of the herbicide glyphosate was studied with the specific background of the presence of genetically modified (GM) plants. Aim was to simulate the environmental behaviour of glyphosate in sandy field soil lysimeters after multiple herbicide applications and under the presence of GM soybean and to test and enhance model reliability in the simulation of the herbicide fate including biodegradation in the soil and herbicide translocation in GM plants. The modelling of the herbicide behaviour in the present study was based on the pesticide transport model LEACHP and the model PLANTX to simulate the pesticide uptake by plants. Both models were implemented in the modular modelling system EXPERT-N. Glyphosate transport measurements and the mathematical modelling results indicate that due to the high sorption of glyphosate to the soil matrix and the high microbial capacities for glyphosate degradation in the lysimeter soil, leaching risk can be considered to be low. We confirmed that the introduction of more adequate conceptual descriptions of microbial response to pesticide and nutrient additions can contribute to a reduction in the uncertainty of pesticide degradation modelling. Moreover, the consideration of uncertainty in sorption, dispersivity and degradation parameters revealed a considerable variability in model output. The observed accumulation of glyphosate in roots and nodules was reproduced by the simulation results. Under the restriction that the prevailing model assumptions are valid, the simulation results indicate that glyphosate may accumulate also in beans of trangenic soybean.

Human exposure to volatile organic compounds (VOCs) and residential indoor and outdoor VOC levels had hitherto not been investigated in Turkey. This study details investigations of indoor, outdoor, and personal exposure to VOCs conducted simultaneously in 15 homes, 10 offices and 3 schools in Kocaeli during the summer of 2006 and the winter of 2006–2007. All VOC concentrations were collected by passive sampling over a 24-h period and analyzed using thermal desorption (TD) and a gas chromatography/flame ionization detector (GC/FID). Fifteen target VOCs were investigated and included benzene, toluene, m/p-xylene, o-xylene, ethylbenzene, styrene, cyclohexane, 1,2,4-trimethylbenzene, n-heptane, n-hexane, n-decane, n-nonane, n-octane and n-undecane. Toluene levels were the highest in terms of indoor, outdoor, and personal exposure, followed by m/p-xylene, o-xylene, ethylbenzene, styrene, benzene and n-hexane. In general, personal exposure concentrations appeared to be slightly higher than indoor air concentrations. Both personal exposure and indoor concentrations were generally markedly higher than those observed outdoors. Indoor target compound concentrations were generally more strongly correlated with outdoor concentrations in the summer than in winter. Indoor/outdoor ratios of target compounds were generally greater than unity, and ranged from 0.42 to 3.03 and 0.93 to 6.12 in the summer and winter, respectively. Factor analysis, correlation analyses, indoor/outdoor ratios, microenvironment characteristics, responses to questionnaires and time activity information suggested that industry, and smoking represent the main emission sources of the VOCs investigated. Compared with the findings of earlier studies, the level of target analytes in indoor air were higher for several target VOCs, indicating a possible trend toward increased inhalation exposure to these chemicals in residential environments.

Nitrated Polycyclic Aromatic Hydrocarbons (NPAH) were determined in the suspended particulates collected in São Paulo (Brazil) and three other cities lying in the São Paulo State, (namely, Araraquara, Piracicaba and Paulínia), during August 2002 and July 2003. São Paulo samples represented a big difference between two groups of days, one of which characterized by heavy injection of pollutants released by industrial and agricultural activities. Most NPAH congeners identified in the atmosphere were among those usually associated to diesel exhaust, with the three important exceptions of 2-nitrofluoranthene, 2- and 4-nitropyrene. Daytime reactions seemed to promote decomposition of primary fluoranthene and pyrene. Trends of NPAH at all sites seemed to be associated to regional transport of polluted air through air masses passing over sugar cane plantations of São Paulo State.

Prescribed or natural drawdowns occur frequently in reservoirs but their effects on fish populations have been barely studied. As a consequence of a severe drought and the need to optimize water quality, a partial drawdown was prescribed in autumn 2005 to a eutrophic reservoir that provides water supply to a large metropolitan area (Barcelona, Spain). In order to avoid a potential massive fish kill given the reduced oxygen availability and high fish abundance, preventive purse seine fisheries were performed to reduce the fish stock. The fisheries had little effect on the fish assemblage because final population size structure and species composition did not change significantly. The species composition of the purse seine catches varied significantly during the drawdown with higher proportion of bleak (Alburnus alburnus) in pelagic water during the days of worst water quality, confirming that bleak is more tolerant than roach (Rutilus rutilus) to poor water quality and a potential good indicator of water pollution. The weight-length relationship (i.e. condition) of roach and bleak also varied significantly during the drawdown following the same tendency in both species, losing and recovering their weight (4.99% in roach and 5.96% in bleak) in only 16 days. The close relationship found between water quality and fish condition demonstrates that fish condition can be a good metric of the well being of fish, even for extreme short-term changes.