This study compared the tolerance limits of selected bacterial (Bacillus licheniformis, Brevibacillus lactosporus and Pseudomonas putida) and protozoan (Aspidisca, Trachelophyllum and Peranema) species to V5+ in wastewater systems. The isolates were exposed to various concentrations of V5+ (from 10 to 240 ppm), and their tolerance limits to this heavy metal were assessed at different temperatures (25, 30, 35 and 40°C) and pHs (4, 6, 7, 8 and 10) for 5 days. Chemical oxygen demand (COD), dissolved oxygen (DO) and die-off rate of the isolates were measured using standard methods. The results indicated that test isolates were tolerant to V5+, with a gradual decrease in their colony/cell counts when V5+ concentration gradually increased. Bacterial species were found to be more significantly tolerant (MIC: 110–230 ppm V5+) to V5+ than protozoan species which showed an earlier total inhibition/die-off rate (100%) at 60–100 ppm V5+ (MIC) (p < 0.001). P. putida was the most tolerant bacterial species (MIC: 230 ppm V5+) and Aspidisca sp. the most sensitive protozoan species (MIC: 60 ppm V5+). An increase in COD and DO removal was observed throughout the experimental period. The highest COD increase (up to 237.11%) and DO removal (almost 100%) were observed in mixed liquor inoculated with P. putida after exposure to 10 ppm V5+. Changes in pH and temperature affected the tolerance limits of all isolates. This study suggests the use of these tolerant bacterial and protozoan species in the bioremediation of V5+ from domestic and industrial wastewater under the control of pH and temperature.

The utilization and disposal of alkaline waste materials such as slag and coal fly ash as cement aggregates and raw materials in cement manufacturing can pose environmental and health hazards because these waste materials usually contain elevated concentration of toxic elements. This study examined the possibility of controlling the pore water chemistry of these waste materials in order to induce the secondary mineral formation of Mg-bearing minerals as major sorbing solids for oxyanions during the utilization and disposal of alkaline wastes. The formation of Mg-bearing minerals was examined at ambient temperature and alkaline pH conditions in the Mg–Si–Al system. The interaction of Mg-bearing minerals with oxyanions using arsenate as an analog was examined during and after mineral formation. The results revealed that the generated Mg-bearing mineral phases were smectite and brucite in Mg–Si system and hydrotalcite and serpentine in Mg–Si–Al system. Moreover, hydrotalcite, serpentine, brucite, and smectite phases formed under low Si ratio showed high sorption capacity for arsenate, but only high Al content hydrotalcite and serpentine showed substantial irreversible fraction of sorbed arsenate. Hence, the generation of these kinds of hydrotalcite and serpentine phases as scavengers for oxyanions must be considered during the utilization and disposal of alkaline wastes.

In epidemiological studies, ultrafine particle (UFP) data from a single monitoring site are generally used as a measure of population exposure potentially resulting in exposure misclassification. From August 2009 to October 2010, 1-week campaigns were conducted during each season. The temporal and spatial variations of UFP number size distributions were investigated at 12 monitoring sites distributed across a 9 × 9 km urban area in Rochester, New York using a Fast Mobility Particle SizerTM spectrometer. The overall average number concentrations of 5.6- to 560-nm particles in summer, winter, spring, and fall were 9,025, 10,939, 4,955, and 14,485 cm−3, respectively. Coefficients of divergence and correlation coefficients were calculated between site pairs to assess the spatial heterogeneity in the particle number size distributions. Moderate spatial divergence and uniform temporal variation were found for the chosen sites. Elevated UFP number concentrations were observed near highways, off-road diesel engines, and residential wood combustion sources, indicating significant contributions to the UFP exposure of people living adjacent to these sources. Our results suggest that one stationary monitoring site may not represent the actual human UFP exposure over a whole urban area.

This study examined the impact of oxidative stress indicated by thiobarbituric acid reactive substances (TBARS) and protein carbonyl (PC), induced by intensive exercise and cadmium chloride (CdCl₂) on ethoxyresorufin-O-deethylase (EROD) activity in juvenile carp (Cyprinus carpio). In the first experiment, fish were divided into three groups: (1) control, (2) carp exposed to intensive exercise, and (3) carp that was not exercised but previously, as well as carp in group 2, received single dose of 3-methylcholantrene (3-MC). The third and sixth day fish were sacrificed and the measurements were conducted. In the second experiment, fish were divided into (1) control, (2) carp in water containing CdCl₂, and (3) carp in dechlorinated tap water (2 and 3 received single dose of 3-MC on the seventh day after exposure to CdCl₂). The carp were killed 6 days later and livers were excised for biochemical analyses. In the first experiment, on the sixth day after treatment with 3-MC, results show statistically significant increase in EROD activity in non-exercised carp, while that increase in carp exposed to intensive exercise was significantly lower. Three days after exposure to 3-MC, statistically significant increase in TBARS was observed in both exercised and non-exercised carp. Six days after exposure to 3-MC, PC levels were significantly higher in exercised carp. Pretreatment with CdCl₂, in the second experiment, caused oxidative stress and reduction of EROD activity. Results show linkage between expression of EROD activity and oxidative stress biomarkers and possible influence of oxidative stress on the cell membrane structures and consequently on EROD activity.

Faecal contamination of drinking water extracted from alluvial aquifers can lead to severe problems. River water infiltration can be a hazard for extraction wells located nearby, especially during high discharge events. The high dimensionality of river–groundwater interaction and the many factors affecting bacterial survival and transport in groundwater make a simple assessment of actual water quality difficult. The identification of proxy indicators for river water infiltration and bacterial contamination is an important step in managing groundwater resources and hazard assessment. The time resolution of microbial monitoring studies is often too low to establish this relationship. A proxy-based approach in such highly dynamic systems requires in-depth knowledge of the relationship between the variable of interest, e.g. river water infiltration, and its proxy indicator. In this study, continuously recorded physico-chemical parameters (temperature, electrical conductivity, turbidity, spectral absorption coefficient, particle density) were compared to the counts for faecal indicator bacteria, Escherichia coli and Enterococcus sp. obtained from intermittent sampling. Sampling for faecal indicator bacteria was conducted on two temporal scales: (a) routine bi-weekly monitoring over a month and (b) intense (bi-hourly) event-based sampling over 3 days triggered by a high discharge event. Both sampling set-ups showed that the highest bacterial concentrations occurred in the river. E. coli and Enterococcus sp. concentrations decreased with time and length of flow path in the aquifer. The event-based sampling was able to demonstrate differences in bacterial removal between clusters of observation wells linked to aquifer composition. Although no individual proxy indicator for bacterial contamination could be established, it was shown that a combined approach based on time-series of physico-chemical parameters could be used to assess river water infiltration as a hazard for drinking water quality management.

Conventional clay capping for post-closure management of landfill commonly cracks and deteriorates over time. As a consequence, water ingress into waste increases as a function of time, potentially causing a range of environmental issues. An alternative approach is known as phytocapping, which utilizes select plant species to control cap stability and moisture percolation. In this study, growth of Arundo donax L. (giant reed), Brassica juncea (L.) Czern. (Indian mustard), and Helianthus annuus L. (sunflower) on a landfill site was studied with different biosolid amendment rates (0, 25, and 50 Mg ha−1). Cultivation of the landfill cap and amendment with biosolids significantly improved the characteristics of the soil. Growth of each plant species increased due to biosolid addition. Giant reed produced the largest biomass in the 50 Mg ha−1 biosolid amendment rate (38 Mg ha−1 dry weight). The high pH and clay content of landfill cap soil, and the low metal concentrations of the biosolid resulted in low heavy metal (copper, zinc, cadmium, and lead) accumulation in leaves of most treatments. The improvement in growth and limited uptake of metal contaminants to plant shoots indicated that biosolid application to landfill clay caps improves the application of phytocapping of old landfill sites.

We present in this paper a new strategy based on the use of polynomial chaos expansion (PCE) for both global sensitivity analysis and parameter optimization. To limit the number of evaluations of the direct model, we develop a simple and efficient procedure to construct a sparse PCE where only coefficients that have a significant contribution to the variance of the model are retained. Parameter estimation is performed using an adaptive procedure where the intervals of variation of the parameters are progressively reduced using information from sensitivity analysis calculated using the sparse PCE. The strategy is shown to be effective for the parameter estimation of two reactive transport problems: a synthetic reactive transport problem involving the Freundlich sorption isotherm and a field experiment of Valocchi et al. (Water Resources Research 17:1517–1527, 1981) involving nonlinear ion exchange reactions.

2-Methylisoborneol (2-MIB) and trans-1,10-dimethyl-trans-9-decalol (geosmin) are two commonly observed taste and odor compounds present in drinking water sources. The effects of pH on the analysis of the two chemicals are investigated using a gas chromatograph and mass spectrometric detector (GC/MSD) coupled with three pre-concentration methods, namely solid-phase micro-extraction (SPME), purge-and-trap concentration (PTC), and liquid–liquid extraction (LLE). At neutral and alkaline pH conditions, the concentrations detected for both compounds remain constant. However, a substantial reduction of concentration for both chemicals is observed when the water solution pH is less than 5. Under acidic conditions (pH ≅ 2.5), the 2-MIB concentrations detected by GC/MSD coupled with SPME, PTC, and LLE are 87%, 16%, and 37% lower than those measured at pH 6–7, respectively. For geosmin, a decrease in concentration is only observed when using GC/MSD-SPME, presumably due to the higher extraction temperature compared to the other two techniques. The pH-dependent behavior was attributed to dehydration of the tertiary alcohols of 2-MIB and geosmin under acidic conditions. The dehydration for 2-MIB and geosmin is reversible, and the analysis can be mitigated by adjusting the water solution pH back to a neutral condition.

Among the many anthropogenic abiotic stresses, manganese (Mn) toxicity has been recognized for its impact on aquatic ecosystems as well as on the biological components of these ecosystems, including aquatic plants. The objective of this study was to determine the Mn accumulation ability of aquatic macrophytes (Azolla caroliniana, Salvinia minima and Spirodela polyrhiza) and evaluate the morphophysiological responses of the species that gather the highest amount of Mn when exposed to a supra-optimal supply of manganese. The experiments were conducted in the laboratory, and the effects of Mn were evaluated based on plant growth; the concentration of total chlorophyll, carotenoids, and anthocyanins; the enzymatic activity of catalase and peroxidase; and leaf anatomy. All of the studied species accumulated Mn in their tissues. Moreover, it was observed that this accumulation was dependent on the concentration of the metal in solution. S. polyrhiza showed higher concentrations of Mn in its tissues (17.062 mg g−1 dry weight (DW)), followed by S. minima (4.283 mg g−1 DW) and A. caroliniana (1.341 mg g−1 DW). Despite the Mn accumulation in all species, S. polyrhiza was the only one selected for further analyses because of its greater ability to accumulate Mn. The high Mn concentration found in tissues of S. polyrhiza suggests that this species has the potential to sequester and accumulate this metal. However, a sensitive response in the plants exposed to higher Mn concentrations (0.4 mM) was observed. The phytotoxicity effects of this accumulation were responsible for a decrease in the plant growth, a reduction in the pigment content (total chlorophyll, carotenoids, and anthocyanins), a low activity of catalase, and the disarrangement of the leaf aerenchyma.

The relative transport and attenuation of bacteria, bacteriophages, and bromide was determined in a 5 m long × 0.3 m diameter column of saturated, heterogeneous gravel. The average pore velocity (V), longitudinal dispersivity (α x ), and total removal rate (λ) were derived from the breakthrough curves at 1, 3, and 5 m, at a flow rate of 24.8 L h−1. The experiments largely confirmed the differences in transport and attenuation patterns among bacteria, phages, and bromide, and between colloid-associated and “free” microorganisms, previously observed in a study using homogeneous pea gravel. Cultured Escherichia coli J6-2 cells were transported faster than phage MS2 and bromide, consistent with velocity enhancement of the larger particles. The evidence for velocity enhancement of phage MS2 compared with bromide was less conclusive, with some evidence of retardation of the phage as a result of adsorption–desorption processes in the finer media. On average, phage in sewage and adsorbed to kaolin particles were transported faster than free phage, suggesting that most sewage phage are adsorbed to colloids. However, average velocities of cultured and sewage E. coli differed far less, suggesting that most E. coli in sewage exist as individual (non colloid-associated) cells. There was no conclusive evidence that the wider pore size range in the heterogeneous mixture compared with pea gravel increased velocity enhancement effects. Removal rates of free phage were far higher than in the pea gravel, and were attributed to adsorption in the finer materials. Equivalent increases in removal of cultured and sewage E. coli and colloid-associated phage were attributed to straining in finer materials and settling in quiescent zones. Inactivation (μ) rates (determined in the pea gravel study) indicated little contribution to removal of either free or attached microorganisms. The results showed the importance of association with colloids in determining the relative transport of bacteria and viruses in alluvial gravels.