Concentrations of particulate emissions from a quarry located in hilly terrain were calculated by two common atmospheric dispersion models, AERMOD and CALPUFF. Evaluation of these models for emissions from quarries/open pit mines that are located in complex topography is missing from the literature. Due to severe uncertainties in the input parameters, numerous scenarios were simulated and model sensitivity was studied. Model results were compared among themselves, and to measured total suspended particulate (TSP). For a wide range of meteorological and topographical conditions studied, AERMOD predictions were in a better agreement with the measurements than those obtained by CALPUFF. The use of AERMOD's “Open pit” tool seems unnecessary when accurate digital topographic data are available. Onsite meteorological data are shown to be crucial for reliable dispersion calculations in complex terrain.

The limited transport of nanoscale zero-valent iron (nZVI) in porous media is a major obstacle to its widespread application for in situ groundwater remediation. Previous studies on nZVI transport have mainly been carried out in quartz porous media. The effect of carbonate minerals, which often predominate in aquifers, has not been evaluated to date. This study assessed the influence of the carbonate minerals in porous media on the transport of polyacrylic acid modified nZVI (PAA-nZVI). Increasing the proportion of carbonate sand in the porous media resulted in less transport of PAA-nZVI. Predicted travel distances were reduced to a few centimeters in pure carbonate sand compared to approximately 1.6 m in quartz sand. Transport modeling showed that the attachment efficiency and deposition rate coefficient increased linearly with increasing proportion of carbonate sand.

The aim of this study was to improve our understanding of metal bioavailability in soil by linking the biotic ligand approach with toxicokinetics modelling. We determined cadmium bioaccumulation kinetics in Folsomia candida (Collembola) as a function of soil pH. Animals were exposed for 21 days to LUFA 2.2 soil at 5 or 20 μg Cd g−1 dry soil followed by 21 days elimination in clean soil. Internal cadmium concentrations were modelled using a first-order one-compartment model, relating uptake rate constants (k1) to total soil, water or 0.01 M CaCl2 extractable and porewater concentrations. Based on total soil concentrations, k1 was independent of soil pH while it strongly increased with increasing pH based on porewater concentrations explaining the reduced competition of H+ ions making cadmium more bioavailable in pore water at high pH. This shows that the principles of biotic ligand modelling are applicable to predict cadmium accumulation kinetics in soil-living invertebrates.

Many lake ecosystems worldwide experience severe eutrophication and associated harmful blooms of cyanobacteria due to high loadings of phosphorus (P). While aluminum sulfate (alum) has been used for decades as chemical treatment of eutrophic waters, the ecological effects of alum on coupled metal and nutrient cycling are not well known. The objective of our study was to investigate the effects of an in-situ alum treatment on aluminum and nutrient (P, N, and S) cycling in a hypereutrophic lake ecosystem. Our results indicate that the addition of alum along with sodium aluminate (as a buffer) increased dissolved aluminum and sulfate in the surface and pore waters, and altered nitrogen cycling by increasing nitrous oxide (N2O) concentrations in the surface water. The increase of aluminum and sulfate may potentially feedback to alter benthic community dynamics. These results enhance our understanding of the unintended ecological consequences of alum treatments in hypereutrophic freshwater ecosystems.

The aggregation, transport and deposition kinetics (i.e. attachment and release) of TiO2 nanoparticles (nano-TiO2) were investigated as a function of ionic strength and the presence of anionic (sodium dodecylbenzene sulfonate, SDBS) and non-ionic (Triton X-100) surfactants in 100% critical micelle concentration (CMC). The electrolyte concentration of the suspensions dictated the kinetic stability of nano-TiO2 thus influencing the transport and retention of the nanoaggregates in the saturated porous medium. With increasing ionic strength, the interaction between approaching nano-TiO2 and nano-TiO2 already deposited onto collectors surfaces seemed to be more favorable than the interaction between approaching nano-TiO2 and bare collectors surfaces. The abrupt and gradual reduction in electrolyte concentration during the flushing cycles of the column experiments induced the release of previously deposited nano-TiO2 suggesting attachment of nano-TiO2 through secondary energy minimum.

This study analyzes changes in the total (intrinsic and acquired) resistance of autochthonous bacteria in a river which is a receiver of treated wastewater. In the analyzed samples, tetracycline contamination levels were low and characteristic of surface water bodies. An increase in the populations of tetracycline-resistant and fluoroquinolone-resistant microorganisms was noted in downstream river water samples in comparison with upstream river water samples, but the above trend was not observed in bacteria resistant to macrolides and β-lactams. The counts of doxycycline-resistant bacteria (DOXR) were significantly correlated with doxycycline levels. The minimum inhibitory concentrations (MICs) for doxycycline in DOXR isolates were higher in downstream river water than in upstream river water samples. The discharge of treated wastewater had no effect on the multi-drug resistance of oxytetracycline-resistant and doxycycline-resistant isolates. The results of the experiment indicate that the presence of doxycycline-resistant bacteria is a robust indicator of anthropogenic stress in river water.

The negative health effects of simulated acid mists and fluoranthene on juvenile Japanese red pine were investigated, and the methods of protection from these pollutants were examined. The needle gas exchange, chlorophyll fluorescence, chemical contents and visual damage to needles caused by acid mist applied alone or its conjunction with fluoranthene were investigated over 60 d and 20 d, respectively. Acid mist at pH 2 and 3 caused physiological and visual damage, which was enhanced by the addition of fluoranthene to the mist. However, fluoranthene and acid mist at pH 4 and 5 showed only minor effects. These findings indicate that acid mist may be more harmful to pine trees if it occurs in conjunction with polycyclic aromatic hydrocarbons. Moreover, suppression of the singular and additive effects of these compounds was achieved using mannitol, which may be widely applicable to suppression of reactive oxygen species-mediated plant damage.

Exposure to atrazine in small lotic systems can be episodic, with short-term pulses (peaks) followed by lower, decreasing concentrations. Algae and macrophytes recover rapidly from pulsed exposure to atrazine, but reported observations of population response to subsequent exposures are minimal and inconclusive. Consequently, the sensitivity of Pseudokirchneriella subcapitata to atrazine following a pulsed exposure was assessed. Exposure concentrations reflected amplifications of those observed in streams from highly vulnerable watersheds in regions of intense use. Initial pulsed atrazine exposure at 0, 150 or 300 μg/L for 24-h was followed by 72-h exposure to 0, 5, 10, 25, or 50 μg/L. Measured responses were cell density, growth rate, chlorophyll-a, and maximum quantum yield of photosystem II. Algal recovery was rapid and prior pulsed exposure to atrazine did not significantly affect subsequent sensitivity (EC10s, EC25s) for any endpoint, indicating no changes in tolerance at the population level for this species.

In this work, a recently developed urban-scale atmospheric dispersion model (DAUMOD-GRS) is applied to evaluate the ground-level ozone (O3) concentrations resulting from anthropogenic area sources of NOx and VOC in the Metropolitan Area of Buenos Aires (MABA). The statistical comparison of model results with observations (including new available data from seventeen sites) shows a good model performance. Estimated summer highest diurnal O3 1-h concentrations in the MABA vary between 15 ppb in the most urbanised area and 53 ppb in the suburbs. All values are below the air quality standard. Several runs are performed to evaluate the impact of possible future emission reductions on O3 concentrations. Under all hypothetical scenarios, the maximum diurnal O3 1-h concentration obtained for the area is slightly reduced (up to 4%). However, maximum diurnal O3 concentrations could increase at some less urbanised areas of MABA depending on the relative reductions of the emissions of NOx and VOC.