bluuebunny/crossref_metadata_2025_split huggingface dataset:
Value of Supplemental Air in Improving RBC Performance
Authors: Surampalli Rao Y. , Tekippe Rudy J. , Baumann E. Robert 
Published: March 2019

Abstract
Rotating biological contactors (RBCs) have been used extensively, but the process units had structural and operational problems. The main problems were related to low dissolved oxygen levels, resulting in thicker biomass growth in the initial stages. This paper discusses the observed value of supplemental aeration in improving RBC performance and in ensuring longer media and shaft life because of reduced mass of biofilm growth. Three full-scale upper-midwest RBC plants, having supplemental aeration in the first two stages, were studied to determine the value of supplemental air in improving RBC performance and in controlling Beggiatoa growth. These plants were operated over a fairly wide range of organic loading. The study results indicated that it was possible to achieve higher BOD5 removal rates when RBCs were provided with supplemental air. In addition, higher dissolved oxygen levels, resulting from the supplemental air, enhanced BOD5 removal and ammonia nitrification significantly. The resulting thinner biofilms also ensured longer life for the media and shaft. Supplemental aeration can be provided with nominal capital investment.
Sediment Records of Man’s Activities in the Kootenay Lake Drainage Basin
Authors: Macdonald R.W. , Carmack E.C. , Pharo C.H. 
Published: March 2019

Abstract
Four cores from Kootenay Lake have been dated using 2l0Pb. These cores have also been analyzed for total Pb concentration specifically to compare the sediment record with the known history of lead-zinc mining around the lake. Two sorts of impact on the lake are recorded in the sediments. First, there is obvious contamination by Pb in which concentrations within cores parallel the regional “boom-and-bust” mining history. Second, the sedimentation rate appears to have been affected by damming of the inflowing rivers and probably also by logging and the associated road construction in the watersheds. Spatial variability within the lake sediments is evident: sedimentation rate is highest towards the north and south ends of the lake where river inflow is greatest; contamination by Pb is highest in the middle of the lake close to the major mining activities.
Phosphorus Dynamics in Riverine Lakes
Authors: Kenney B.C. 
Published: March 2019

Abstract
Simple models based on conservation of mass capture the essential dynamics of total phosphorus in lakes. The concentration of total phosphorus in shallow riverine lakes on the Prairies was simulated as a forced response to the inflow concentration. The lake dynamics were characterized by three independent time scales based on water inflow, water outflow and sedimentation. Both inflow and outflow time scales were necessary to model lakes with non-stationary hydrographe and varying lake levels. Flood periods had a pronounced effect on lake phosphorus because high concentrations in the inflow occurred when the lake was dynamically able to respond. In the Fishing Lakes, the 1974 flood appears to have established the lake conditions for the next decade. Most other large peaks in the concentration of total phosphorus in the inflow occurred when the outflow time scale was large and the lakes were dynamically unable to respond. Net sedimentation of total phosphorus appeared to be zero in these lakes over the two decades for which data were available. Verification of the lack of net sedimentation in shallow lakes means that no model calibration is needed to apply these simple models to other shallow lakes. Presently, however, even the simplest models are restricted by the lack of appropriate data required for verification.
Studies of Bottom Ekman Layer Processes and Mid-Lake Upwelling in the Laurentian Great Lakes
Authors: Saylor James H. 
Published: March 2019

Abstract
Profiles of horizontal current velocity have been measured over long time intervals across bottom Ekman layers in Lake Michigan. Measurements at offshore locations in water depths greater than 100 m have disclosed current speeds exceeding 25 cm s"1 at 1 m above the lake floor during winter storms when the lake water is unstratified. Counterclockwise veering of the current velocity vector occurs as the bottom is approached, with the veering being most rapid close to the bottom. Measurements of currents during winter and spring have shown prevailing cyclonic circulation at all water depths. This is true of the other deep Great Lakes as well. Mass conservation calculations with the current meter data yield upwelling velocities on the order of 1 m day'1 in the center of the lake during winter. Water temperature data have been obtained from thermistor strings attached to meteorological buoys moored in the center of the lake by the National Data Buoy Center, Bay St. Louis, Mississippi. Simulations of the temperature data with four different one-dimensional mixed layer models were all premature in timing the onset of stratification. Additional simulations of the temperature data were made with a constant upwelling velocity imposed through late spring. Results of the new simulations were significantly improved over those neglecting upwelling. These results emphasize the importance of Ekman pumping in retarding the start of stratification in large lake basins.
Some Aspects of the Thermal Regime of Large Lakes: Lake Ladoga and Lake Onega
Authors: Naumenko M.A. 
Published: March 2019

Abstract
Physical limnological experiments relating to water temperature and currents were conducted in lakes Ladoga and Onega over the period 1985–90. Details of the lake thermal cycle, thermal bar formation, circulation, and heat flux characteristics in the region of the thermal front in these two large lake systems are described. In addition, consequences relating to chemical and biological distributions in the area of thermal front development and progression are discussed.
Anaerobic Detoxification of a Chemi-Thermomechanical Pulp Effluent by Two Acclimating Sludges
Authors: Patoine Alain , Côté Raynald , Paquet Marcel 
Published: March 2019

Abstract
Detoxification of a chemi-thermomechanical pulp effluent (CTMP) was examined by monitoring toxicity and resin acid concentration during treatment in batch reactors. Two treatments were carried out — one performed with an industrial granular sludge and the other with a municipal anaerobic digester sludge. The two sludges were acclimated to the CTMP effluent by successive 6-day suspended growth cycles on fresh effluent. In both cases, several growth cycles showed resin acid and toxicity increases, probably caused by resin acid desorption from bacterial cell walls to the aqueous phase. Detoxification of the effluent was achieved with both sludges during the last growth cycle. Since measurements were performed on filtered samples, the observed decreases of toxicity and resin acid concentration may be the result of bacterial degradation or of adsorption of toxic substances on particulate matter. Major increases of resin acid were associated with major toxicity increases within one given growth cycle.
Release of Arsenic from Model Wastewater Treatment Solids: A Mechanism Based on Surface Ligand Exchange
Authors: Paige C.R. , Snodgrass W.J. , Nicholson Ronald V. , Sharer J.M. 
Published: March 2019

Abstract
The loss of arsenic from model wastewater treatment solids has been studied by neutron activation analysis. The data show that the loss of arsenic from unstirred solids is controlled by a surface exchange reaction and also clearly demonstrate that arsenic is not retained in a solid solution. This is in contrast to metal ions which are retained in crystalline solids as solid solutions. The activation energy Eafor the exchange reaction is calculated to be 40 kJ/mol. Data were retrieved for the half-time of arsenic exchanging from these solids. The presence of arsenic, either in the solid or in the aqueous phase contacting the solid, altered the kinetics of transformation to and the crystalline nature of the final products. These data have implications for the disposal of wastes to landfill.
Possibilités et limites des bassins lagunaires dans l’épuration des eaux usées
Authors: Bontoux J. , Picot B. 
Published: March 2019

Résumé
Les techniques d’épuration des eaux usées par lagunage correspondent à des procédés très diversifiés dont la conception doit être parfaitement adaptée à chaque problème posé dans un contexte climatique particulier. Les possibilités des systèmes épurateurs sont grandement fonction de leur gestion qui doit particulièrement tenir compte des cycles saisonniers et parfois aussi des cycles nycthéméraux. Les limites sont étroitement dépendantes des mauvaises conditions de l’éclairement hivernal. L’exposé des résultats d’un programme expérimental sur le lagunage à haut rendement algal illustre la complexité du fonctionnement d’un système lagunaire même simplifié et montre les possibilités d’amélioration des performances offertes par une gestion séquentielle des rejets d’eau traitée hors des bassins.
Transformation of the Herbicide Diclofop-Methyl in a Large-Scale Physical Aquifer Model
Authors: Headley J.V. , Lawrence J.R. , Zanyk B.N. , Brooks Paul W. 
Published: March 2019

Abstract
Products arising from the transformation of diclofop-methyl were studied under isothermal steady-state conditions in a meso-scale aquifer model. In general, the transformation products observed for the model were similar to those previously reported for field experiments. Some significantly different products were observed for the model in which there were: (i) preferential formation of 4-(2,4-dichlorophenoxy)dehydrophenetole instead of the analogous 4-(2,4-dichlorophenoxy)phenetole and 4-(2,4-dichlorophenoxy)-phenol, and (ii) formation of chlorinated metabolites of benzoic acid. Although the latter chlorinated metabolites were formed by an unknown process, the mechanism appears to occur via interactions with ubiquitous contaminants present in the soil. Formation of the polar chlorinated metabolites was linked to the prevalence of phthalate esters in environmental samples. Based on increased polarity, the latter chlorinated metabolites were predicted to be more mobilized in the presence of water than the parent herbicide.
Toxicity of Sulfite and Cadmium to Anaerobic Granular Sludge
Authors: Shew C.F. , Kosaric N. 
Published: March 2019

Abstract
Toxicity of sulfite (Na2SO3) and cadmium (CdCl2) ions to anaerobic granular sludge was investigated in 1.2 litre bench-scale upflow anaerobic sludge blanket (UASB) reactors during process acclimation and shock load conditions. Minimal sulfite toxicity was observed under gradual and shock load conditions at sulfite concentrations of up to 1000 mg S/L if proper acclimation was allowed to occur. No long-term toxic effects were observed although the COD digestion rate was temporarily inhibited by shock load of sulfite. Scanning electron micrographs indicated that more sulfate-reducing bacteria were present in the granules developed in the reactors with sulfite supplement although rod-shaped Methanosaeta-like bacteria were still dominant. High bacterial growth rate was observed in the reactors which were supplied with the feed containing sulfite. The COD digestion rate was inhibited at a cadmium loading rate of 2.4 g Cd per day under both acclimation and shock load conditions. Acclimation did not seem to improve the bacteria to tolerate the toxicity of cadmium. The concentration of free cadmium was very low in the reactors under normal conditions, but increased rapidly when the COD digestion in the reactors ceased. The bacteria could not be reactivated after inhibited by cadmium. When reactors were operated at low specific COD loading rates, more inorganic precipitates were formed inside the granules which consequently settled faster.
Heavy Metal Pollution in Sediments and Waters of the Penang River, Malaysia
Authors: Seng Chye-Eng , Lim Poh-Eng , Chong Poh-Kim , Wong Lee-Mai 
Published: March 2019

Abstract
The concentrations of zinc, copper, lead and nickel in the Penang River and its tributaries were determined to assess the extent of heavy metal pollution, and to evaluate which compartment provides a better indicator for heavy metal pollution. The results indicate that the concentrations of total and non-residual heavy metals in sediments increase significantly towards the estuary of the river. This trend is, however, not obvious for heavy metals in the river water. The data indicate that assessment of heavy metal pollution in rivers could be made by using the data of heavy metal levels in river sediments. It is suggested that non-residual heavy metal levels in sediments give the best indication of anthropogenic input of heavy metals to river systems.
Photocatalytic Discolouration of Solutions of Reactive Dyes in the Presence of H2O2
Authors: Nansheng Deng , Shizhong Tian , Mei Xia 
Published: March 2019

Abstract
Tests for the photocatalytic degradation of solutions of three reactive dyes, Red M-5B, Procion Blue MX-R and Procion Black H-N, in the presence of H2O2 were carried out. When the solutions of the three reactive dyes were irradiated by UV or solar light, the colour of the solutions disappeared gradually. A statistical analysis of the test results indicated a linear relation between the concentration of dyes and the time of irradiation. The discolouration reaction of the solutions was of the first order. Rate equations for the discolouration reactions of dye solutions were developed.
The dark reactions or the dye solutions containing H2O2 were very slow, illustrating that the photochemical reaction played a very important role. It was demonstrated that UV light and solar light (300 to 380 nm) photolyzes the HO and that the resulting OH radical reacts with the dye molecules and destroys the chromophore.
A Nested-Grid Hydrodynamic/Pollutant Transport Model for Nearshore Areas in Hamilton Harbour
Authors: Tsanis Ioannis K. , Wu Jian 
Published: March 2019

Abstract
A nested-grid depth-averaged circulation model was developed and applied to three nearshore areas in Hamilton Harbour: the western basin, LaSalle Park waterfront and the northeastern shoreline. The grid sizes used were 100 m for the whole harbour, and 25 m for the three nearshore areas. General features of current circulation and horizontal mixing times under various wind directions and speeds were obtained for the whole harbour using the coarse-grid model. The fine-grid model (water elevations and current information on the open boundaries were obtained from the whole harbour model) then provided current patterns which were used to drive the pollutant transport model. Simulation results reveal that the current in the fine-grid model is close to the current from the coarse-grid model, while more detailed current structures are explored. The water elevations from the fine-grid model agree well with the elevations from the coarse-grid one. The impact of artificial islands was examined by studying changes in current patterns, pollutant peaks, exposure and flushing time in different locations of concern. The design proposed provides: (i) minimum change in the existing current patterns; (ii) avoidance of pollutant hot spots; and (iii) minimum changes in the flushing time of pollutants.
Chemistry of Snowmelt from an Urban Lysimeter
Authors: Westerström Göran 
Published: March 2019

Abstract
A 200-m2 lysimeter, representing an urban paved plot, was installed in Lulea, Sweden, instrumented and monitored during the 1986 snowmelt season. Hourly and daily flow-proportional composite samples of snowmelt were collected and analyzed for pH, Cl−, NO3− and SO42− ions. The fractionation of these parameters in snowmelt was observed, indicating low pH values and high concentrations of the ions studied in the early phases of snowmelt relative to the parent snow cover. The corresponding concentration factors ranged from 5 to 8. Fluxes of hydrogen ions in snowmelt showed high values during the early phases of snowmelt, commonly described as an early (first) pollutant flush. For this type of pollutant transport response, the pollution load could be effectively controlled by storing and/or treating the initial heavily polluted part of total snowmelt and allowing the rest to bypass the control facility. By storing and/or treating the first quarter of the total meltwater volume, almost two thirds of the total hydrogen ion load could be controlled.
Sorption of Cadmium and Nickel in Activated Sludge
Authors: Kodukula Prasad S. , Patterson James W. , Surampalli Rao Y. 
Published: March 2019

Abstract
Distribution of cadmium and nickel between operationally defined soluble and solid phases of activated sludge was investigated. The metal sorption process was characterized by describing it quantitatively as a function of time, pH and suspended solids concentration. Reversibility of the sorption process was studied by comparing metal adsorption and desorption edges. The effect of desorption kinetics on hysteresis of nickel was investigated. Equilibrium adsorption isotherms were developed for cadmium and nickel in activated sludge at different pH levels, and sorption capacity of solids and conditional stability constants for metals-sludge reactions were determined using the Langmuir adsorption model.
Prediction of Pesticide Leaching on a Watershed Basis: Methodology and Application
Authors: Reynolds W.D. , de Jong R. , van Wesenbeeck I.J. , Clemente R.S. 
Published: March 2019

Abstract
Methodology consisting of a numerical solute transport model (LEACHM), combined with geostatistical analysis (kriging) and a geographic information system (GIS), was developed to predict and characterize low-level, nonpoint source pesticide contamination of groundwater on a watershed basis. A preliminary test and evaluation of the methodology was conducted by applying it to the prediction of atrazine contamination of groundwater in the Grand River watershed in Southern Ontario. Atrazine loading to the groundwater was predicted to be highly variable spatially (CV = 164%), but low-level (0 to 2.5 mg atrazine/m2/year) and less than 2% of the surface application (150 mg atrazine/2/year). The predicted concentration of atrazine in the groundwater never exceeded the Canadian drinking water guideline of 60 ppb, but exceeded the 3 ppb U.S. EPA standard in about 27% of the watershed area. These predictions were in general agreement with recent groundwater survey results, which found that nonpoint source atrazine contamination of groundwater in the watershed was highly variable spatially and generally low-level, but occasionally exceeding the U.S. EPA standard. Although these preliminary results are encouraging, more development and testing of the methodology is required.
Investigation and Remediation of Groundwater Contamination at a Pesticide Facility — a Case Study
Authors: Carter R.S. , Stiebel W.H. , Nalasco P.J. , Pardieck D.L. 
Published: March 2019

Abstract
Soil and groundwater beneath a 22-year old agrichemical formulating and warehousing facility in Cambridge, Ontario, have been impacted with pesticides in addition to volatile organic and nitrosoamine compounds associated with their formulation. Thirty-three compounds, including 15 pesticides released to the soil from an underground process wastewater system, concrete-lined pits, storage areas and infrequent spills, are present in the water table at a depth of 10 m in overburden sediments. Groundwater flow in the overburden is complex and dissolved compound migration is influenced by spatially variable vertical hydraulic gradients induced from the underlying dolostone aquifer which is pumped by municipal supply wells located at distances ranging from 600 m to 1500 m from the site. One pesticide, metolachlor(2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-l-melhylethyl) acetamide), has been measured consistently above Ontario drinking water objectives in the overburden and at a depth of 30 to 39 m below ground surface in the bedrock aquifer adjacent to the site. A groundwater pump and treat system is operating and is controlling further off-site migration of dissolved compounds in the overburden, and treating the captured groundwater with granular activated carbon.
Mesocosms for Subsurface Research
Authors: Lawrence J.R. , Hendry M.J. 
Published: March 2019

Abstract
This article provides an overview of mesocosm research applied to investigations of subsurface processes. The nature of mesocosms and the mesocosm concept are defined and discussed as are the advantages and disadvantages of these systems. In general, a mesocosm meets the requirements of being of sufficient size to contain all the components of interest while permitting “natural” behaviour. It is implicit in the use of mesocosms that they act as a surrogate for the real ecosystem. However, the precise size of a mesocosm is difficult to define without a specific context. Details are provided on the construction, filling and instrumentation of subsurface mesocosms. This article also provides recent examples of applications of mesocosms to studies of biogeochemistry, waste disposal and fate and transport of a herbicide. In addition, a comparison of physical, chemical and microbial data from a mesocosm (diameter 2.44 m × 4.6 m) with a 3-m thick vadose zone and water table and its associated field site is made. Mesocosms provide the advantages of controlled environment, near steady-state conditions, and environmentally acceptable testing of the fate and effects of toxics. However, considerable research is required to optimize their size, instrumentation and expand their application to in situ conditions as well as the laboratory.
Seasonal Loadings of Atrazine and Metolachlor to a Southeastern Ontario River from Surface Runoff and Groundwater Discharge
Authors: Fischer J.D. , Apedaile B.E. , Vanclief L.K. 
Published: March 2019

Abstract
The Payne River in the South Nation River basin in eastern Ontario was continuously sampled for atrazine and metolachlor from April to October during 1991 and 1992, using a modified Quality Environment Ltd. automatic liquid sampler. The objectives of the study were to determine weekly flow proportional concentrations and loadings to the river, and to assess loadings during dry weather periods for evidence of contributions from groundwater discharge. In 1992, samples were also analyzed for desethylatrazine, the predominant residue of atrazine. The site southeast of Ottawa represented a watershed area of 182 km2. The maximum concentration of atrazine were recorded for the weeks ending May 29, 1991 (0.83 µg/L), and July 30, 1992 (1.20 µg/L. These values were approximately half the Canadian Water Quality Guideline for the Protection of Freshwater Aquatic Life (2 µg/L). Maximum concentrations of metolachlor were also recorded for these dates. Values were 0.43 µg/L and 0.26 µg/L, respectively, well below the Canadian Water Quality Guideline of 8 µg/L for the Protection of Freshwater Aquatic Life. Discharge data were used to calculate weekly loadings from the watershed, and seasonal loadings were compared with the results of a pesticide usage survey. Atrazine loadings to the Payne River as a percentage of atrazine applied during both cropping seasons were the same (0.13%) despite different discharge patterns. Metolachlor loadings were similar for both years and less than the value for atrazine. In 1991, 0.01% of the metolachlor applied to the study area reached the river during that cropping season. The corresponding value for 1992 was 0.03%. Atrazine loadings associated with carry-over from the previous cropping season were an important factor during the study period. Observed atrazine loading before application in a given year exceeded the loading for the entire cropping season of that year. The compounds were also present in river water under dry weather conditions, suggesting that in addition to surface runoff, groundwater is also a significant source of pesticides to the Payne River.