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Most of the currently available streamflow neural network models are either recurrent neural networks or feed-forward multi-layer perceptron (FF-MLP) requiring past flow values for lead time prediction. These models cannot be used for modelling ungauged watersheds because past flow values are not available in such cases. This study proposes a FF-MLP algorithm that relies only on low-cost, readily available meteorological data and careful time series manipulation prior to model building, and thus, is suitable for modelling streamflow in ungauged watersheds. The proposed approach was tested on four watersheds (5 to 130 km2) in the Canadian Boreal forest and was found to provide an efficient modelling alternative for daily streamflow predictions. To assess the possibility of successful model transferability from a gauged watershed to a hydrologically similar ungauged watershed, a new remotely sensed hydrologic similarity measure — SWMIR_SI — was proposed and was found to provide a successful indicator of basin similarity. The square of Pearson's correlation coefficient, r2, was evaluated to exceed 0.71 when SWMIR_SI was regressed to models' "goodness-of-fit" statistics reflecting the usefulness of the approach. [ABSTRACT FROM AUTHOR]

This study is an effort to incorporate low-cost time-variant remote sensing (RS) information in watershed-scale total phosphorus (TP) modelling. Four watershed subdivisions were delineated to assess the impact of watershed subdivision on the prediction accuracy of TP concentration in stream water. Four TP artificial neural network (ANN) models were designed to incorporate RS data into a semi-distributed approach. The remotely derived enhanced vegetation index and the normalized difference water index were successful in representing vegetation dynamics in the devised models. The models were applied to a 15.6 km2 watershed in the Canadian Boreal Plain. Eight measures of goodness-of-fit statistics were used for model evaluation. Although statistical model evaluation did favour the finest resolution in this case study, the differences in performance indicators among the four models were insignificant for any practical application. The encouraging results from this exercise demonstrate the applicability of the ANN semi-distributed modelling approach and the usefulness of RS data in simulating TP dynamics. Such models can potentially serve as valuable tools for watershed-scale forest management. [ABSTRACT FROM AUTHOR]

This investigation presents new and aggressive approaches to link the results of scientific endeavor to management of a portion of the Canadian boreal forest, within the framework of the detailed forest management plan (DFMP) process of a forestry company in the province of Alberta. The first component in the DFMP was landscape projection, whereby cumulative impacts of key natural and anthropogenic disturbance agents were modelled under current and altered climate conditions. The second component addressed two types of impact assessment. The Biodiversity Assessment Project (BAP) modelled ecosystem diversity at landscape and habitat levels, as well as developed habitat supply models, relative to changing vegetation composition, management practices, and stand age. Models were used during the development of a preferred forest management strategy to address undesirable ecological predictions. In the Forest Watershed and Riparian Disturbance (FORWARD) project, a variant of the soil and water assessment tool was developed to model the impacts of watershed disturbance on streamflow. In the third component of the DFMP, timber supply scenarios were devised based on maximizing annual allowable harvest in a sustained yield fashion, while incorporating elements of the BAP and FORWARD project as constraints in harvest sequence optimization. This initiative is an example of an industry-led effort to manage forests using a system that is regionally centered, science based, peer reviewed, and considers multiple activities and their cumulative environmental effects. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The quantum yields of the UV photolysis of free chlorine (OCl– and HOCl) at 254 nm were measured in a series of batch reactor experiments from pH 5 to 10 and at various concentrations. When the concentration of free chlorine is low (3.5 mg Cl/L) to moderate (70 mg Cl/L), the quantum yields of HOCl and OCl– are 1.0 ± 0.1 and 0.9 ± 0.1, respectively. When the concentration increases to higher levels (>70 mg Cl/L), the quantum yield of HOCl photolysis increases significantly, whereas the quantum yield of OCl– photolysis is essentially independent of concentration. In addition, based on the experimental results obtained in this research, a mathematic model was developed that can be used for the prediction of the quantum yield for the UV photolysis of free chlorine at 254 nm. The quantum yields predicted by this model agree very well with the measured data. Also, the dependence of free chlorine decomposition on the fluence (UV dose) and the effect of water quality on the quantum yield of free chlorine species were investigated in this research. [ABSTRACT FROM AUTHOR]

Ozonation of abietic and linoleic acids (resin and fatty acids; RFAs) was investigated at various pHs and low temperatures (0 to 10 °C) using a rapid-scan stopped-flow spectrophotometer. Degradation of abietic and linoleic acids could be enhanced by manipulating reaction conditions, including ozone dose, temperature, and pH. Improved degradation of RFAs at higher pHs suggests hydroxyl radical reaction is playing an important role during the ozonation. The apparent overall second order rate constants were determined based on the pseudo-first order rate constants for acids and for ozone. At pH 11 and 10 °C, they were calculated as 6.6 x 10³ M-1⋅s-1 and 1.0 x 104 M-1⋅s-1 for abietic and linoleic acids. respectively. The acute toxicity assessed by Microtox® bioassay increased after ozonation by 140% in the case of abietic acid, whereas it reduced to half in the case of linoleic acid. [ABSTRACT FROM AUTHOR]

Low-pressure water treatment membranes, microfiltration (MF) and ultrafiltration (UF) have enjoyed unprecedented growth during the past decade. These systems are particularly suited for cold region communities because of their operational simplicity, small footprint, and consistent performance despite the fluctuations in raw water characteristics. Effective operation of MF and UF membrane systems in cold regions, however, must account for the impact of low water temperatures on membrane operation. Of particular interest is the impact of cold water on direct membrane integrity monitoring tests. Most regulatory bodies require that regular integrity monitoring tests be performed for low-pressure membranes to ensure the integrity of the membrane systems. Currently, the most widely-used integrity monitoring test is the pressure decay test. Our studies, however, indicated that the pressure-based direct integrity monitoring tests are affected by variations in water temperature, especially in the range of 0 to 5 °C. The considerable drop in diffusive air flow rates and consequent decrease in pressure decay rate for an intact membrane as water temperatures approach 0 may mask the impact of a defect and should be accounted for. It is suggested that the criteria for membrane integrity tests in cold regions shift downward to account for the effect of temperature. This paper presents the results obtained from studies on the effect of water temperature on the pressure-based direct integrity monitoring tests. [ABSTRACT FROM AUTHOR]

Increased nutrient concentrations in fresh waters may lead to depressed dissolved oxygen concentrations, increased cyanobacterial biomass, and potentially high levels of cyanobacterial toxin production. Phosphorus loading, during snow melt and storm events, is the main source of nutrient enrichment to water bodies on the Canadian Boreal Plain. This study compared two approaches for modelling total phosphorus (TP) concentration: autoregressive moving average with exogenous input (ARMAX) and artificial neural network (ANN) models. Derived models were applied to a small forested watershed on the Canadian Boreal Plain. Results showed that ANN outperformed ARMAX based on four measures of goodness-of-fit statistics. This study confirmed that the ANN modelling approach is superior to ARMAX in modelling time-correlated gapped data, provided step-by-step guidelines for modelling time-correlated variables, and presented a feasible alternative for modelling diffuse pollutants in small forested watersheds. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In developed countries, clean and safe drinking water is taken for granted, and water treatment processes used to mass-produce drinking water have been hailed as one of the top five engineering achievements of the 20th century. However, in the last decade, several waterborne disease outbreaks have made us painfully aware of the personal, economical, societal, and public health costs associated with the impact of waterborne disease. There is evidence to suggest that the prevalence of waterborne disease may be dramatically underestimated in developed countries and that routine endemic exposure to waterborne pathogens may occur more frequently than originally perceived. A variety of demographical, societal, environmental, and physiological emergence factors likely play critical roles in enhancing the frequency of transmission of pathogens to hosts. This review focuses on the scope and impact of waterborne disease in developed countries and identifies issues surrounding the potential for rapid global emergence or re-emergence of waterborne disease. We examine relevant literature on Cryptosporidiumparvum and Escherichia coli O157 as model organisms of study that support these concepts. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Morphological changes of Giardia lamblia cysts after treatment with ozone, free chlorine, or combinations of oxidants were documented using transmission electron microscopy. Experiments were conducted using in vitro- derived G. lamblia cysts. Nucleic acid staining employing LIVE/DEAD BacLight™ was used for the evaluation of cyst viability. Cyst wall damage, plasmalemma breakage, lysis of peripheral vacuoles, and nuclear degradation were main features of cyst injury elicited by ozone or chlorine. Cell death pathways were found to be oxidant-specific. Morphological changes in G. lamblia cysts treated with both ozone and chlorine showed that the preconditioning of the cyst wall by exposure to the first oxidant allowed for easier penetration and increased damage induced by the second oxidant. Taken together, our results indicate that pretreatment of G. lamblia cysts with low doses of one oxidant significantly increases the susceptibility of the parasite to the sequentially applied second oxidant. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Presents information on a study which measured the bubble size, bubble rise velocity, bubble size distribution and gas-phase turbulence intensities in an impinging-jet bubble column using a two-dimensional laser particle dynamics analyzer. Measurement methods; Results and discussion; Conclusions.

Examines the microbial involvement of the induced floc formation. Isolates found capable of enhanced flocculation; Roles of the bacteria; Categories of species.

The article discusses various reports published within the issue regarding the application of ultraviolet light to air, water and wastewater treatment.

Discusses the use of ultraviolet (UV) light for the treatment of pathogens and degradation of pollutants. Barrier to the use of UV in drinking water treatment; Advantage of UV-driven oxidation technologies.

Introduces several articles about environmental hydraulics and hydrotechnical communities.

An introduction to papers on environmental engineering published within the issue and presented at the 12th International Conference on Cold Regions Engineering held in Edmonton, Alberta by the American Society of Civil Engineers (ASCE) and other organizations, is presented.

In the past few years, artificial neural networks (ANNs) have been used in describing and modelling wastewater treatment processes. Artificial neural network models can be identified without a detailed knowledge of the kinetics of the system to be modelled. Also, ANN models can potentially contain a great deal of information about the system itself, including the same type of information contained in conventional deterministic models. The fact that these models can be continuously updated with minimal resource requirements makes them very attractive for application in a real-time control scenario. In the current paper, applications of ANNs in the field of wastewater treatment performance prediction are reviewed. In addition, this paper presents a case study that reports some comprehensive modelling work to develop nonlinear neural network prediction models for the Gold Bar Wastewater Treatment Plant (GBWWTP), the largest sewage treatment facility in Edmonton, Alberta. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Deals with the mission of the periodical "Journal of Environmental Engineering and Science." Improvement of the quality of life for all living things; Importance of environmental issues; Information on manuscripts published in the January 2002 issue of the journal.