The adsorption and photocatalytic degradation of methyl orange (MO) aqueous solution under visible light illumination by polythiophene/titanium dioxide (PTh/TiO₂) composite particles were studied. The experimental observations from UV-vis spectrophotometer indicate that MO molecules were degraded in a different degree during the visible light-induced photocatalysis reaction. We propose a new degradation mechanism of MO during the photocatalytic reaction, based on blue shift of UV-vis absorption spectra of MO solution and other researches. The data from total organic carbon analyzer definitely prove that MO can be mineralized to CO₂ and H₂O, and some intermediate products are generated during the photocatalysis degradation of MO.

This study proposes a two-phase optimization model for regional air pollution control. To predict the pollutant concentrations at receptor zones, an interval Gaussian plume model is advanced to facilitate the generation of optimal pollution control policies. Results from the case study indicate satisfactory performance of the proposed model in handling uncertainties in parameters expressed as intervals and in stipulations associated with pollutant emission and ambient air quality. Compared with conventional models, it has advantages of generating compromised management strategies according to decision makers' preference. This would be useful when the guarantee of satisfying all constraints is inapplicable or too costly. The proposed model is capable of identifying key factors and/or input conditions that may intensely affect system outputs and thus facilitating decision makers in adjusting current system status to benefit future management. The results also reveal a significantly enhanced satisfactory level would be obtained compared with conventional “single-phase”-based optimization models.

Prairie grasslands are very species rich but have declined in their extent considerably due to land-use change and exploitation. Many remaining prairie fragments are situated within an agricultural matrix and can be subjected to high levels of atmospheric ammonia deposition from animal units. Three prairie fragments in Minnesota that were located in close proximity to feedlots were selected, and 500-m transects were studied at an increasing distance from the feedlot. Changes in soil pH, soil nitrate concentration, and soil ammonium concentration with increasing distance from the source were variable between the sites, possibly due to differences in the processing of nitrogen in the soil and the degree of nitrogen limitation. Species richness showed significant negative relationships with ammonia deposition and soil nitrate concentration, whereas aboveground biomass showed a positive relationship with ammonia deposition. Both the richness and biomass of nongraminoid species declined with increasing soil nitrate concentration, whereas graminoid biomass was positively related to ammonia deposition and was negatively associated to richness. Bromus inermis, a non-native perennial grass, was the main species that increased at high deposition. The results of this study have important implications for the conservation and restoration of prairie grasslands.

This study aimed to understand the seasonal and spatial variations of N₂O emissions from newly created littoral marshes in the drawdown area of the Three Gorges Reservoir (TGR), China. We measured N₂O emissions at 10-day intervals during the growing season (early July to late September) in 2008. N₂O emissions were measured with static chambers in four typical vegetation stands. The results showed great spatial variations of N₂O emissions among the four stands. The greatest N₂O emissions (0.052 ± 0.063 mg N₂O m⁻² h⁻¹) were from Scirpus triqueter stand, while the lowest N₂O emissions (0.020 ± 0.020 mg N₂O m⁻² h⁻¹) were from Typha angustifolia stand. To such spatial variations in N₂O emissions, standing water depths and soil water content may be important explaining factors. Besides spatial variations, we also found significant temporal variations of N₂O emissions in this area. The temporal variation of N₂O emissions in the growing season was not found significantly related to any measured factor in the study. However, based on principal component analysis, we consider it partly caused by thermal conditions and the marked temporal variation of the standing water depth in the growing season, which to some degree influenced the process of denitrification and N₂O emissions. These results about TGR enable us to make a more reasonable estimate of N₂O emissions from large dam reservoirs, particularly those with a large drawdown area in the growing season in an agricultural landscape.

Assessing air quality in street canyons is a crucial concern, as the highest pollution levels and threshold exceedances are usually experienced within this kind of urban streets. A brief overview based on experimental studies and modelling techniques undertaken in literature is presented, including characteristic features affecting wind flow and pollutant dispersion within street canyons. In this work, a numerical street canyon model intercomparison has been performed in a typical urban canyon in Florence, Italy. In particular, STREET, Canyon Plume Box Model (CPBM) and Operational Street Pollution Model (OSPM) have been applied to compute the street-level 1-h carbon monoxide (CO) concentrations. In addition, the CALINE4 model has been applied to test the site morphology. Input data cover a 1-year time period and include meteorological observations as well as measured traffic volumes and driving speeds. Hourly road emissions have been calculated using the COPERT methodology taking into account vehicle fleet, traffic flows and driving speed, as well as ambient temperature to account for cold overemissions. A preliminary experimental data analysis has been carried out in order to investigate the dependence of observed CO concentrations on meteorological and traffic parameters. Hourly CO concentrations observed over the full year have been used to compare the STREET, CPB and OSP models, resulting in a detailed statistical analysis carried out by wind sector as well as on a seasonal basis.

The contamination status of rivers and their floodplains with inorganic and organic pollutants in central Russia is poorly known. We investigated the concentrations of inorganic (As, Cd, Cu, Hg, Ni, Pb and Zn) and persistent organic pollutants (hexachlorocyclohexane, PCBs, cyclodienes, DDX and other pesticides) in floodplain soils of the Oka River catchment (Russia). The level of contamination was generally lower than in the Elbe River floodplain but in the same range as in other European river systems such as floodplains of the rivers Rhine, Dřevnice and Yachroma. Only soil samples from the periphery of the city of Ryazan (200 km southeast of Moscow) had a higher anthropogenic enrichment of Cd, Cu and Zn which was comparable to the contaminated Elbe River floodplains. These soils also had the largest concentrations of persistent organic pollutants among all samples from the Oka River catchment. Therefore, the need for large-scale remediation seems to be less urgent than in Central European river catchments and mainly restricted to some “hot spot” areas.

Mining wastes may pose risk nearby urban and agricultural areas. We investigated a lettuce crop land close to a former capped mine tailing in order to determinate the metal uptake by crops. Soil plot sampling design within the crop area and two transects along the tailing were performed. In addition, lettuces (root and leaves) were analyzed after transplant and harvest. The results showed a pH of around 7-8 for all the soil samples. Total metal concentrations were as follows: 190-510 mg kg⁻¹ Pb, 13-21 mg kg⁻¹ Cu, and 210-910 mg kg⁻¹ Zn. Diethylene triamine pentaacetic acid-extractable Pb was around 18% of the total Pb in some samples. Transects along the base and on the plateau of the tailing showed high metal concentrations of Pb (up to 5,800 mg kg⁻¹) and Zn (up to 4,500 mg kg⁻¹), indicating that capping layer had been eroded. Lettuce leaves showed Pb concentrations within standard for human health (<0.3 mg kg⁻¹ in fresh weight). For essential micronutrients such as Cu and Zn, leaves had optimal content (10-28 mg kg⁻¹ Cu, 60-85 mg kg⁻¹ Zn). A continued monitoring in metal uptake is needed in crop lands close to mining wastes in order to prevent risks in food safety. Capped tailings must be monitored and rehabilitation works performed from time to time.

This work describes the evolution of NO₂ and O₃ levels from January to December of 2007, covering the four seasonal periods in the urban air of Ciudad Real in the central-southern Spain. The measurements were carried out by means of passive samplers (Radiello® samplers). Eleven samples were collected weekly, placed at different monitoring site locations. The data indicate that the mean levels obtained during this period for O₃ and NO₂ were 38.5 ± 3.5 and 20.8 ± 3.8 μg/m³, respectively. These measurements were compared with other studies in Ciudad Real. Meteorological conditions (temperature, pressure, humidity relative, wind speed and direction) were also investigated.

A meso-scale pilot plant was set up to test the efficiency of a phytoremediation technique applied to slightly contaminated marine sediments dredged from the port of Livorno (central Italy). The technique applied involved the use of plants (a grass species, Paspalum vaginatum and a shrub species, Tamarix gallica) and earthworms (Eisenia foetida sp.) in order to recreate an active ecosystem in which plants, micro- and macroorganisms could interact with each other through the rhizosphere, for the adsorption, extraction and/or degradation of pollutants. This system enables plants to grow in a fine textured and salt medium highly unsuitable for plant species, and a physical, chemical and biological amelioration of the matrix was observed at the end of the experimentation (after 9 months). The sediment was bio-physically pre-conditioned by mixing it with calcareous material from excavating activities (5:1 v/v) and applying green compost. The presence of microorganisms in the rhizosphere and the earthworms produced a reduction by about 50% of the initial total petroleum hydrocarbon content. The use of a natural chelator with phyto-hormonal properties (humic substances) showed their capability of forming stable complexes, especially with Pb, and their contribution as an agronomic fertiliser. The combined effect of the P. vaginatum and T. gallica in the extraction of heavy metals from the sediment showed promisingly high percentages of metal effectively extracted in comparison with its available fraction (e.g. available Ni = 6.2%; Ni extracted = 15.7%). The technique proposed could be promising for an operational re-use of dredged marine sediments for agricultural purposes, a suitable final destination for the great majority of these contaminated materials from rivers and harbour docks.

Lake Vela (Littoral Centre of Portugal) is considered a natural habitat with community interest and consequently was included in the Natura 2000 Network. However, this freshwater ecosystem has been potentially exposed to diffuse pollution generated by agricultural and livestock activities, which seriously compromise its ecological balance. As part of the Ecological Risk Assessment (ERA) proposed for Lake Vela, this study aimed to evaluate the occurrence of pesticides in different compartments: surface water, groundwater, sediments, and fish tissues. Moreover, to assess potential concerning effects on ecosystem and human health, the measured concentrations of pesticides were compared with regulatory and toxicological benchmarks. The results confirmed the presence of high concentrations of pesticides, including organochloride pesticides banned decades ago, in surface water, groundwater, and sediment. The measured concentrations of pesticides, compared with toxicological benchmarks, indicated that harmful effects are likely for aquatic species due to the presence of alachlor, aldrin, and dieldrin. Additionally, the concentrations of pesticides detected in groundwater were also above the recommended safety levels for drinking water, which constitutes a concern for the local population's health. Results also showed an accumulation of alachlor in predator and benthic fish species which could represent a risk to human consumers and particularly to the regular fish predators (e.g., otters and birds). This study, as the first exposure characterization performed on the Lake Vela system, constitutes valuable and useful information for the ERA process. Although this preliminary assessment of risks should be continued and confirmed through a weight-of-evidence approach, it had already unraveled how concerning are the problems in this ecosystem and the urgency of implementing restoration measures to guaranty its sustainability. Furthermore, this study reinforces the importance of evaluating similar freshwater ecosystems that are also highly threatened by diffuse pollution.