Aqueous natural organic matter (NOM) impacted by two contrasting human impacts was analyzed using by multiresponse fluorescence, decoupled with the resolution routine PARAFAC. The first site is Chalk River, Ontario, Canada, near a pit formerly used to dispose low-level wastes. The second site is the Grand River in Cambridge, south-central Ontario, which is impacted by urban activities and agriculture. Our analysis included raw water, plus fractions from ultrafiltration and solid-phase extraction (SPE). The fluorescence spectra of the NOM, resolved with PARAFAC, showed three common features: humic-like components, at excitation/emission wavelengths 325-350/450-475 nm, fulvic-like components at 325/380-420 nm and protein-like components, at 275/300 nm. Ultrafiltration revealed that most of the NOM comprised fine material below 5,000 Da cut-off (<4% of the total) in the urban-impacted sites and the clean site at Chalk River, but the colloidal fraction (larger than 5,000 Da) was substantially higher in the contaminated water, with ∼18-26% of the total. The protein-like components in the contaminated Chalk River water were affected by ultrafiltration, but less so in the clean Chalk River sample and the urban-impacted waters. SPE preferentially removed the protein-like component in the contaminated Chalk River water (typically 89-95% signal decrease), but had a limited effect on humic- and fulvic-like components elsewhere. In conclusion, multiresponse fluorescence provided new information on the NOM quality from two contrasting sites, aided by ultrafiltration and SPE. These results are consistent with the in situ production of NOM in the Chalk River contaminated site, and natural production at the other sites.

Hourly concentrations of non-methane hydrocarbons (NMHCs) recorded between June and August 2006, at two monitoring sites (Gijang and Jin) in Busan were analyzed to examine the characteristics and photochemical reactivity of NMHC sources. The two sites represent urban (Jin) and suburban (Gijang) Busan, which is a typical Korean city. Positive matrix factorization (PMF), applied to identify and apportion the sources of NMHCs, revealed nine sources for Gijang and ten sources for Jin. To explore the contribution of each NMHC source to ozone formation at the two sampling sites, the ozone formation potential was estimated for each source. The largest contributors to ozone formation were sources characterized by 1,2,3-trimethylbenzene (26.4%) at Gijang and by toluene, ethylbenzene, and xylenes (22.5%) at Jin, which were composed mostly of heavy hydrocarbons and aromatics. Secondary sources included two coating sources (20.9%, 12.2%) and vehicle exhaust (10.3%) at Gijang and a source represented by toluene (17.4%), vehicle exhaust (15.9%), and a coating-2 source (9.6%) at Jin. Conditional probability function (CPF) and potential source contribution function (PSCF) analysis methods were used to identify the directions of local sources and to locate potential source regions, respectively. The CPF and PSCF results agreed well for the majority of sources resolved by PMF and thus were very useful in identifying the major sources contributing to ozone formation at the two study sites.

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.

Wastewater land application is a cost-effective method to treat and dispose wastewater; however, it may cause soil salinization. Salt mass balance and the potential soil salinization caused by the wastewater land application were investigated in the crop root zone in a wastewater land application system at the City of Littlefield, TX, USA from October 7, 2005 to September 28, 2007 using a lysimeter system. This study showed that, after 2 years of wastewater land application, the ranges of soil salinity were still lower than the threshold (8,500 μS/cm) for Bermuda grass assuming a 10% yield reduction. The leached salt mass showed large spatial and temporal variation. The average values of electrical conductivity of the saturated paste extract of the soil samples increased from 1,433 μS/cm in June 2006 to 1,840 μS/cm in June 2007. The average values of the soil sodium adsorption ratio between June 2006 and June 2007 increased from 11 to 14 resulting in a potential risk of soil dispersion and decreasing the soil infiltration rate. Although the measured leaching fractions in nearly all sampling periods, except one, were higher than the leaching requirement, salt accumulations in the root zone were still found with only two exceptions. Since the time required for reaching equilibrium between cumulative salt mass input and cumulative salt mass output varies from 1 year to a few years, or even longer, the long-term investigation is recommended for the study of salt mass balance in the root zone of this wastewater land application system.

Methylibium petroleiphilum PM1, which is capable of degrading of methyl tert-butyl ether (MTBE), was immobilized in calcium alginate gel beads. Various applications were explored to increase the mechanical strength of these gel beads. The introduction of 0.3 mol/L calcium chloride into the crosslinking solution, 0.002 mol/L calcium chloride into the growth medium, and 0.2% polyethyleneimine (PEI) as chemical crosslinking agent increased the stability of the Ca-alginate gel beads under the operation conditions of the bioreactor. The degradation rates of MTBE by the immobilized cells in the bioreactor system operated in batch and continuous mode , respectively, were compared. A MTBE biodegradation rate of 5.79 mg/L·h was reached for over 400 h (50 batches), and the immobilized cells in the bioreactor removed >96% MTBE during 50 days of operation. Molecular analysis of the PM1 cells revealed that microbial growth occurred predominantly as microcolonies in the outer area of the beads during the first 20 days of operation. The results of this study show that a continuous-mode, fixed-bed bioreactor reactor coupled with PM1-immobilized cells is a promising technology for remediating MTBE-contaminated groundwater.

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.

Different substrates were evaluated to investigate their effect on nitrate removal and denitrifying bacterial community in soils obtained from wetland. Serial batch kinetic tests were conducted on soils obtained from wetland mixed with glucose and sawdust using KNO3 solution. Column tests were also conducted on soils obtained from wetland mixed with three different substrates (glucose, sawdust, and scoria coated with zero-valent iron) using KNO3 solution. For the batch tests, the nitrate removal efficiency for soil mixed with glucose was comparable to that for soil mixed with sawdust, but the nitrate removal rate for soil mixed with glucose (23.3 NO3 −-N mg/L-d) was approximately eight times higher than that for soil mixed with sawdust (2.8 NO3 −-N mg/L-d). For column tests among soil samples, nitrate removal efficiency was highest in soil mixed with glucose, which is an easily biodegradable carbon source. Removal efficiency increased with increasing incubation time for both soil samples with glucose and sawdust. A phylogenetic analysis based on nitrate reductase gene demonstrated that the different carbon sources affected both the diversity and compositions of the denitrifying bacterial in soil samples.

The presence of recent dichlorodiphenyltrichloroethane (DDT) inputs is established for Paranaguá Bay biota, i.e. bivalves, fish and one sponge. Values ranged from 6.9 to 156.2 ng ΣDDT/g dry weight. Three fish species analysed showed ΣDDT values from 36.8 to 92.1 ng/g dry weight. The highest contents (up to 156.2 ng ΣDDT/g dry weight) were found for mangrove oysters (Crassostrea rhizophorae) at locations affected by sewage discharge from Paranaguá City. Turtles as herbivores were not affected by this input with values of 0.7 and 2.2 ng ΣDDT/g dry weight. The areal distribution of samples suggests that usage of DDT is widespread around the bay. Fresh DDT input is degraded to DDE and DDD within approximately 5 months.

Riparian buffer strip guidelines are under scrutiny in the River Njoro Watershed in Kenya. This study investigated soil properties (bulk density, carbon, nitrogen, and phosphorus) in different land use types (small scale agriculture in recent settlements, mixed agriculture in established peri-urban settlements, large-scale commercial agriculture, and the gazetted forest reference condition) and their adjacent buffer strips. Bulk density, carbon, nitrogen, and phosphorus within 30-m riparian buffer strips adjacent to recent settlement land use areas were similar to those of the gazetted forest reference condition, but only bulk density of the buffer strips adjacent to peri-urban and commercial agriculture land use areas were similar to the gazetted forest reference condition. Phosphorus is a sensitive indicator of the impacts of human activity, as increased concentrations were observed with increasing scale of land use activity. For riparian buffers adjacent to recent settlements, soil phosphorus was significantly higher in buffers narrower than 30 m (5.01 mg P kg−1) than gazetted forest (3.40 mg P kg−1) but not significantly different for riparian buffers wider than 30 m (3.81 mg P kg−1) compared to gazetted forest. Based on the research, it is recommended that policies governing riparian buffer strips become (1) stricter, with the current “maximum” of 30 m considered a minimum; and (2) adaptive, with 30 m used in small-scale agricultural areas, and wider riparian buffer strips used in medium- and large-scale agricultural areas.

Pollution of water bodies with heavy metal ions is a major worldwide environmental problem. The objective of this study was to elucidate the mechanism in which metallic ions are adsorbed and reduced to metallic nanoparticles onto plant materials using microwave radiation. In this research, we have fabricated metallic silver and lead nanoparticles from their corresponding ions using the aquatic plants Azolla filiculoides and Pistia stratiotes (since identical results are obtained for both plants, the emphasis will be on the Azolla) under microwave radiation. Our data show that metallic silver and metallic lead nanoparticles were completely removed from the polluted solution and were embedded in the A. filiculoides surface after 5 min of microwave reaction. It was also found that, for both metals, reduction of the metallic ions was accomplished by the plant matrix without the need of an external reducing agent. Most of the particles had a spherical shape within the 10–50 nm size range. Mass balance data clearly indicate that most of the silver particles were found on the surface of the plant and not in the clean water. Pectin and α-glucuronic acid did not reduce the silver or lead ions under microwave radiation. We therefore hypothesize that perhaps the proteins or sugar alcohols in the plant matrix were serving as the reducing agents. We believe that this technique in which adsorption and reduction are combined using microwave radiation can be applied for removing and recycling metallic ions from contaminated water and industrial wastewater.