The research presented here represents a segment of a cumulative impact assessment of resource development in northeastern British Columbia. It considers point and area source emissions of sulphur and nitrogen oxides (SO₂ and NO x , respectively), over a 2,156-km² area. With the exception of open burning, all emissions are from Upstream Oil and Gas (UOG) sector sources (SO₂, n = 103; NO x , n = 250; area, n = 25). AERMOD View™ was used to estimate the maximum potential concentration and deposition of these pollutants over 1-h, 3-h, 24-h, and annual averaging periods. Results are compared with various thresholds and limits from the policy and scientific literature to assess the potential cumulative effects of these pollutants. Of the thresholds employed, exceedances of the 1-h and 24-h NO x concentrations and the annual SO₂ concentration are predicted. There were no predicted exceedances of annual deposition thresholds (i.e., “Critical Loads”). Maximum predicted concentrations vary between compounds and are related to boundary layer stability, elevation, and distance from sources. Comparison with nearby monitoring data indicated that predicted concentrations were reasonable and that AERMOD provides a useful tool for approaching the potential cumulative impacts of air pollution from multiple sources. While the accuracy of Gaussian-based annual deposition estimates is questioned, model enhancements that could extend the application to more comprehensive assessments are suggested. Lastly, the implications of predicted threshold violations for forest ecosystems and local forest-dependent First Nations communities are discussed.

Ambient concentrations of photochemical oxidants (Ox) averaged throughout all ambient monitoring stations in Japan have increased slightly during the past two decades despite decreasing emissions of oxidant precursors such as NOx and hydrocarbons. In the Kanto area of Japan, which is heavily populated and industrialized, Ox concentrations are often high, especially in late spring and summer, and a photochemical smog warning is frequently issued. Although the north Kanto area is about 150 km from the southern metropolitan area, and, moreover, local emissions of precursors are limited because of its agricultural and forested character, high Ox concentration levels (>120 ppbv (1-h average)) are often observed there. We analyzed the relationship between the occurrence of high Ox concentrations in the north Kanto and meteorological conditions. By combining the regional wind pattern and the presence of the inversion layer in the atmospheric boundary layer, we identified five distinct meteorological patterns. High Ox concentrations in the north Kanto area were associated with a southerly extended sea breeze accompanied by a subsidence inversion layer. We inferred that the transport of Ox from the southern urban area by southerly winds and restricted dispersion below the inversion layer can lead to high Ox concentrations in the north Kanto area. This meteorological condition is associated with the presence of a high pressure system centered in the southeastern or eastern sector offshore of the Kanto area. Thus, Ox concentrations in the north Kanto area, where emissions of precursors are relatively low, can easily increase to very high levels under favorable meteorological conditions.

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.

Bacterial associations with plant roots are thought to contribute to the success of phytoremediation. We tested the effect of addition of a polycyclic aromatic hydrocarbon contaminated soil on the structure of the rhizosphere microbial communities of wheat (Triticum aestivum), lettuce (Lactuca sativa var. Tango), zucchini (Cucurbita pepo spp. pepo var. Black Beauty), and pumpkin (C. pepo spp. pepo var. Howden) 16S rDNA terminal restriction fragment length polymorphism (T-RFLP) profiles of rhizosphere microbial communities from different soil/plant combinations were compared with a pairwise Pearson correlation coefficient. Rhizosphere microbial communities of zucchini and pumpkin grown in the media amended with highest degree of contaminated soil clustered separately, whereas communities of these plants grown in unamended or amended with lower concentrations of contaminated soil, grouped in a second cluster. Lettuce communities grouped similarly to cucurbits communities, whereas wheat communities did not display an obvious clustering. The variability of 16S rDNA T-RFLP profiles among the different plant/soil treatments were mostly due to the difference in relative abundance rather than presence/absence of T-RFLP fragments. Our results suggest that in highly contaminated soils, the rhizosphere microbial community structure is governed more by the degree of contamination rather than the plant host type.

The research was carried out in the spruce forests of Barania Góra (Silesian Beskids, Poland) affected by pandemic dying of trees. Twenty-seven samples were collected from the O layer in two plots: 17 in a cut down forest infested with insect pests (bark beetle) and ten in a 120-year-old healthy forest. The analyses covered basic parameters (pHH2O, pHKCl, worg, Ctot, Ntot, CEC) and the concentrations of aluminium in the fractions leached with 0.1 M BaCl2 (Alexch), 0.5 M CuCl2 and 0.1 M Na4P2O7 (Albio) solutions. The total aluminium concentration in the soil was assayed digesting samples with hydrofluoric acid. The effect of pH and organic matter content on the amount of exchangeable (Alexch) and bioavailable (Alexch) aluminium in the soil was analysed. It has been found that the soils in both plots are strongly acidic and contain 550 to 1,700 mg kg−1 of exchangeable aluminium and 1,200 to 4,800 mg kg−1 of bioavailable aluminium. The lack of disease symptoms in the spruce trees in plot 2 can be explained by the higher content of organic matter in the soil. Unfortunately, one might expect that the high concentration of exchangeable aluminium will also cause the trees in the area to wither.

Recently, there has been increasing concern about perfluorinated compounds, especially perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) due to their biotic and abiotic persistence and chronic toxicity. To characterize the spatial distribution and seasonal variation of PFOS and PFOA in the aquatic and oceanic environment of Singapore, more than 100 water samples from reservoirs, rivers/canals, coastal waters, and treated effluents of wastewater treatment plants (WWTPs) were collected and analyzed in this study. Solid-phase extraction followed by high-performance liquid chromatography (HPLC) coupled with tandem MS (HPLC/MS/MS) was applied to quantitatively identify PFOS and PFOA. PFOS concentrations in surface waters, wastewaters and coastal waters were in the range of 2.2–87.3 ng/L, 5.8–532 ng/L, and 1.9–8.9 ng/L, respectively, while those of PFOA were 5.7–91.5 ng/L, 7.9–1,060 ng/L, 2.4–17.8 ng/L, respectively. Compared with surface waters and wastewaters, coastal waters had lower concentrations of PFOS and PFOA. Highest concentration of PFOA (532 ng/L) and PFOA (1,060 ng/L) were observed in treated effluents of two WWTPs. Our results suggest that coastal waters in the western area of Singapore are more heavily contaminated than those in the middle and eastern areas. The release of effluents from WWTPs is an important pathway by which perfluorinated compounds enter the oceanic environment. Between dry season and wet season, significant seasonal differences (p = 0.025) were observed in surface waters for PFOS only, while no discernable seasonal differences were found for both PFOS and PFOA in coastal waters and wastewaters.

Pharmacologically active substances used in the treatment of human and animal illnesses may usually enter the aquatic environment via effluents from sewage treatment plants, as they are not completely biodegraded or removed during waste water treatment. 17β-Estradiol genotoxicity was evaluated in Oreochromis niloticus (family Cichlidae) using micronucleus test, other nuclear abnormalities assessment, and the comet assay with erythrocytes. Fish were exposed to aqueous systems contaminated with 6 ng/L 17β-estradiol for three periods: 24 h, 48 h, and 10 days. The results showed that 17β-estradiol has genotoxic potential in different periods, since significant differences (P = 0.036) were observed in the micronucleus frequencies of the 10-day exposure groups in relation to the control group. Also, the same was observed when comparing the nuclear abnormality frequencies (P = 0.018) of the 24-h exposure group with the negative control group, and when using comet assay (P < 0.001) for 48-h evaluations. The tested concentration of the 17β-estradiol gave rise to mutagenic and genotoxic effects on the blood cells of O. niloticus, therefore the substance being considered a clastogenic chemical contaminant on both acute and chronic exposures. The assessment using a combination of micronucleus test, nuclear abnormalities, and comet assays proved to be suitable and useful in the genotoxicity testing of 17β-estradiol at nanograms per liter.

In this study, microalgae Scenedesmus quadricauda was entrapped in calcium alginate/polyvinyl alcohol composite hydrogel beads by phase-inversion techniques. The composite biosorbents were used for removal of Cu(II) and Cd(II) ions from single component and binary systems using cell-free composite beads as a control system. The effects of the experimental conditions (such as pH, initial metal ions concentrations, temperatures, contact time, and biosorbent concentrations) on Cu(II) and Cd(II) removal efficiencies were studied. The maximum metal ions on the bare and algal biomass immobilized in alginate beads were observed between pH 5.0 and 6.0. The biosorption of metal ions by the bare and composite beads increased as the initial concentration of the metal ions increased in the medium. The biosorption of Cu(II) and Cd(II) on the composite beads appears to be slightly temperature dependent. The maximum biosorptions of metal ions onto microalgae entrapped in composite beads were 0.970 ± 0.028 and 0.682 ± 0.017 mmol/g for Cu(II) and Cd(II) ions, respectively. The equilibrium experimental data for two metallic species fitted well by the Langmuir model. The values of ΔG° at all temperatures are negative, indicating the spontaneous nature of the biosorption process. When the metal ions competed (in the case of the biosorption from their mixture), the amounts of biosorption onto microalgae cells entrapped in beads were 0.857 ± 0.033 mmol/g for Cu(II) and 0.593 ± 0.024 mmol/g for Cd(II). Under noncompetitive and competitive conditions, the affinity order of ions for biosorbents was Cu(II) > Cd(II).

A new approach in soil remediation washing techniques is the use of L-cysteine based on the formation of organic complexes. In this study, the applicability of L-cysteine for the mobilisation of different mercury species from contaminated soils was evaluated. Soils were treated with L-cysteine solutions with S–Hg molar ratios of 1, 2, 10, 20, 100 and 200. In 24 h batch experiments, leachates with water could mobilise 1% of Hg. The addition of L-cysteine led to an increase of Hg mobilisation of 42% for soils with inorganically bound Hg. In column experiments, the maximum Hg removal rate was 75%. For soils with organically bound Hg or HgS, only 1–5% of Hg was mobilised. Thus, the extraction of Hg from soils with L-cysteine is highly dependent on the Hg-binding form. Hg speciation analyses of leachates indicate that Hg–L-cysteine complexes are labile complexes which can be easily transformed. Soil samples speciation analysis revealed that reduction to elemental mercury takes place at low S–Hg ratios (1 to 10), assumingly by microbial activity. At higher S–Hg ratios of 10 and 100, precipitation of stable Hg–S complexes could be observed. These species transformation processes are limitations for considering L-cysteine leaching as a remediation strategy.

It was recently reported that tetracycline could enhance the mobility of manure-derived Escherichia coli within saturated porous media (Walczak et al. (Water Research 45:1681–1690, 2011)). It was also shown, however, that E. coli from various sources could display marked variation in their mobility (Bolster et al. (Journal of Environmental Quality 35:1018–1025, 2009)). The focus of this research was to examine if the observed difference in the mobility of manure-derived tetracycline-resistant (tetR) and tetracycline-susceptible (tetS) E. coli strains was source-dependent. Specifically, E. coli were isolated from Lake Michigan, and the influence of tetracycline resistance on Lake Michigan-derived E. coli was investigated through column transport experiments. Additionally, a variety of cell morphology and surface properties were determined and related to the observed bacterial transport behavior. Our experimental results showed that, consistent with previous observations, the deposition rate coefficients of the tetR E. coli strain was ∼20–100% higher than those of the tetS E. coli strain. The zeta potential of the tetR E. coli cells was ∼25 mV more negative than the tetS E. coli cells. Because the surfaces of the E. coli cells and the quartz sands were negatively charged, the repulsive electrostatic double-layer interaction between the tetR E. coli cells and the quartz sands was stronger, and the mobility of the tetR E. coli cells in the sand packs was thus higher. The tetR E. coli cells were also more hydrophilic than the tetS E. coli cells. Results from migration to hydrocarbon phase (MATH) tests showed that about ∼35% more tetS E. coli cells partitioned to the hydrocarbon phase. As it was previously shown that cell hydrophobicity could enhance the attachment of bacterial cells to quartz sand, the difference in cell hydrophobicity could also have contributed to the observed higher mobility of the tetR E. coli cells. The size of the tetR and tetS E. coli cells were similar, suggesting that the observed difference in their mobility was not size-related. Characterization of cell surface properties also showed that tetR and tetS E. coli cells differed slightly in cell-bound lipopolysaccharide contents and had distinct outer membrane protein profiles. Such difference could alter cell surface properties which in turn led to changes in cell mobility.