ALBERT

Notes: The microbial load and nutritional composition of the Bunaea alcinoe larvae were investigated. The bacterial population of the skin and intestinal content were 8.16 × 106and 5.70 × 105 cfu/g while the fungal populations were 2.07 × 106and 1.32 × 106 cfu/g, respectively. Twenty bacterial isolates belonging to the genera Staphylococcus, Bacillus, Micrococcus and Acinetobacter were isolated. Staphylococcus aureus occurred on both the skin and intestinal content. The nutritional composition of the larvae revealed high protein (55%) followed by fat (25%). Total available carbohydrate, moisture and ash were 4, 8 and 8%, respectively. The public health implication of the presence of S. aureus is highlighted. B. alcinoe larva is a rich source of protein and can be recommended in the diet of communities where protein is scarce or expensive.

Notes: The inhibitory effect of alcohol extract of sumac (Rhus coriaria L.) was investigated at concentrations of 0.1, 0.5, 1.0, 2.5 and 5.0% (w/v) on the growth of 12 bacterial strains (6 Gram positives and 6 Gram negatives), mostly foodborne including pathogens. Minimal inhibitory concentration of the spice for each test organism was also studied by observing their growth on Nutrient Agar containing the spice extract at various incremental levels equivalent to 100–5000 mg/L of spice. Alcohol extract of sumac was found to be effective against all the test organisms, Gram positives being more sensitive than Gram negatives. Among the Gram positives, Bacillus species (B. cereus, B. megaterium, B. subtilis and B. thuringiensis) were found to be the most sensitive, surviving up to only 500 mg/L of the spice, followed by Staphylococcus aureus (1000 mg/L), whereas Listeria monocytogenes was found to be the most resistant, surviving up to 1500 mg/L. Of the Gram negative bacteria, Salmonella enteritidis and Escherichia coli type I were found to be more resistant, surviving up to 3000 mg/L of the spice, followed by E. coli O157:H7 (2500 mg/L), Hafnia alvei (2000 mg/L), Proteus vulgaris (1500 mg/L) and Citrobacter freundii (1000 mg/L). Significant differences (P 〈 0.01) were found among bacterial strains and between the extracts of unripened and ripened sumac samples, with ripened being more effective against all of the bacteria tested.

Notes: The objective of these experiments was to determine whether alternative molting diets would minimize Salmonella enterica serovar Entertitidis (S. Enteritidis) colonization in molting hens. Hens were randomly assigned to four treatment groups of 12 hens either full-fed (nonmolt, NM), molted by feed withdrawal (molt, M), a low calcium (LC containing 800 mg calcium), or LC diet supplemented with 110 mg zinc/ kg of diet (LC-ZN) in two trials. All hens were challenged orally with 10 5SE on day 4 of experiment. Hen body weight loss was significantly (P 〈 0.05) increased and ovarian weight was significantly (P 〈 0.05) decreased in hens fed the LC or LC-ZN diets compared to NM. Cecal lactic acid concentrations were significantly (P 〈 0.05) increased in hens fed alternative molting diets. Feed withdrawal molted hens exhibited significantly (P 〈 0.05) more S. Enteritidis positive and S. Enteritidis crop, cecal, and organ colonization than NM, LC and LC-ZN hens. Alternative molt diets retain sufficient fermentative activity to limit S. Enteritidis colonization and therefore may have potential to avoid the risk of increasing S. Enteritidis colonization associated with feed withdrawal.

Notes: Staphylococcal foodborne diseases resulting from consumption of food contaminated with staphylococcal enterotoxins (SEs) produced by certain strains of Staphylococcus aureus are the second most common foodborne illnesses in the world. Analytical methods are essential for routine monitoring purposes and safeguard public health. Different methods for SE detection have been proposed although their use in a complex matrix is often limited by the presence of substances that interfere with tests. In this article reverse passive latex agglutination (RPLA) and immunoblotting methods based on specific antibodies and currently available for SE detection have been compared. Culture filtrates from enterotoxin S. aureus strains isolated from cheese samples were identified by SET-RPLA. Then the culture filtrates identified as staphylococcal enterotoxin A and staphylococcal enterotoxin B by RPLA test were analyzed with immunoblotting. The results obtained suggest that either SET-RPLA or immunoblotting may be applied to culture filtrates for the detection of SEs with good correspondence of results. Although SET-RPLA represents a simple method for routine monitoring purposes, a positive result by a rapid method (RPLA) is only regarded as presumptive and must be confirmed by standard methods (Feng 1996), such as immunoblotting method.

Notes: Preference testing is commonly used in consumer sensory evaluation. Traditionally, it is done without replication, effectively leading to a single 0/1 (binary) measurement on each panelist. However, to understand the nature of the preference, replicated preference tests are a better approach, resulting in binomial counts of preferences on each panelist. Variability among panelists then leads to overdispersion of the counts when the binomial model is used and to an inflated Type I error rate for statistical tests of preference. Overdispersion can be adjusted by Pearson correction or by other models such as correlated binomial or beta-binomial. Several methods are suggested or reviewed in this study for analyzing replicated preference tests and their Type I error rates and power are compared. Simulation studies show that all methods have reasonable Type I error rates and similar power. Among them, the binomial model with Pearson adjustment is probably the safest way to analyze replicated preference tests, while a normal model in which the binomial distribution is not assumed is the easiest.

Notes: Activity patterns of the suprahyoid muscles were examined using a new analytical technique. The suprahyoid activities were recorded during swallowing of tasteless foods and foods with taste qualities (sweet, salty, sour, bitter and umami). The technique involved: (1) division of cumulative integrated suprahyoid activities from each swallow into 10 equal sections and (2) assignment of individually sectioned activities to a standardized timescale as TP (from T10To T100; relative time for P% of the cumulative electromyogram) to enable comparison of data from different trials. Three significant differences were found in T p between the following foods: tasteless and sour, tasteless and bitter, and sour and umami. However, the differences were not repeatedly confirmed. These results suggest that gustatory signals from food tastes affect differentially the activity patterns of the suprahyoid muscles during pharyngeal swallowing, although the effect is not permanent. This method may be used to measure taste impressions in infants and in certain disabled subjects.

Notes: The purpose of this article is to discuss the issues associated with selecting assessors for sensory panels. It develops the argument that although there are many variations in the detail of how assessors are selected, all panels can be considered as either (1) selecting respondents to measure ingredient concentrations via perceptions or (2) selecting respondents to represent the response that would be obtained from a wider consumer population. The validity of the data collected, i.e., the extent to which the data collected measures what was originally intended, depends on the detail of how assessors were selected as well as a number of other factors.

Notes: Subjects were simultaneously given subthreshold levels of taste and odor stimuli, delivered orally, for both a commonly paired and an uncommonly paired taste–odor combination. Results indicate cross-modal summation of subthreshold concentrations of both taste–odor pairs when the olfactory stimulus is delivered orally. Results of control studies suggest that the summation was indeed across modalities, and not due to the taste of the odor compound or the smell of the taste compounds. Furthermore, results indicate that regardless of taste–odor pair commonness, taste and smell can combine in a completely additive fashion (i.e., at threshold detectability when both stimuli are presented simultaneously at 50% threshold level) if the taste–odor pair is presented orally. In several instances, but not all, measured probabilities exceeded those predicted by probability summation, indicating that hyperadditive mixing often occurs, but there do seem to be individual differences. Cross-modal summation, regardless of taste–odor pair commonness, has broader implications for the development of foods, beverages and pharmaceuticals, especially in masking undesirable tastes and smells.

Notes: The objective of this study was to establish the aromatic descriptors that identify the aroma of young Mencía wines from different geographic areas of Ribeira Sacra Appellation of Origin Controlled in Galicia (NW Spain). Initially, 36 attributes were identified. A multivariate analysis was carried out to evaluate this possible differentiation between the Mencía wines according to production area. Principal component analysis of sensory data permitted the differentiation among geographic areas. The wines differed significantly for seven sensory attributes. The wines from Chantada and Ribeira do Miño were characterized by higher intensities of metallic and bread odors, while Amandi and Quiroga-Bibei by balsamic, apple and phenolic characters. The wines from Ribeira do Sil exhibited a toasting character and the lactic character was present in all wines except those from Ribeira do Sil.

Notes: Psychophysical thinking informs both concept development and product design. With products, the researcher systematically varies ingredients/processes and measures consumer reactions such as acceptance and sensory impressions. The product data generate a model showing how the formulations drive ratings. With concepts (and package designs), the researcher systematically varies the presence/absence of elements/pictures and measures consumer reactions such as acceptance or appropriateness. The concept data generate a model showing how the elements drive reactions. Concept and product research look for relations among variables, at once to understand and also to engineer consumer-acceptable products and messaging.

Notes: The effect of varietal differences and polishing of rice on quality parameters of “idli,” an Indian fermented product, were studied. In addition, the functional properties of decorticated (whole and split) black gram (Phaseolus mungo Roxb.), were also determined. Two varieties of raw rice, “Jaya” and “Minilong,” and one variety of parboiled rice “Ponni” with two degrees of polishing (high and low) were selected. Idlis were prepared following standard procedures. Variations were observed in water and fat absorption capacities of two black gram samples. Emulsification capacity ranged from 102 to 110 mL/100 g. Foam capacities at different pH range were similar, but foam stability differed as a function of time. The pH of the fermented batter was between 4.1 and 4.8. Rice with a lesser degree of polishing fermented better with higher batter volume and microbial count, lesser shear value and gave softer idlis. However, sensory analysis revealed that idlis prepared with low-polish rice scored significantly lower for appearance and color quality compared with products prepared with high-polish rice. Significant differences were observed in the quality of flavor of all products. It can be concluded that the quality characteristics of Idli were influenced by the variety of rice and the degree of polishing, but the two types of black gram used, whole and split, had no effect.

Notes: Rice is the staple food of many countries and its sensory quality is of great concern to the consumers. Its preservation through thermal processing in retort pouches for ready-to-eat purposes was carried out by different time–temperature schedules with and without oil to achieve a minimum Foof 3 min. The sensory analysis of the cooked rice carried out using quantitative descriptive analysis showed that a process schedule of 118C, 8 min was optimum to have the optimal sensory characteristics. The same rice samples were subjected to instrumental texture measurements by texture analyzer using a crosshead speed of 0.5 mm/s with 90% compression for hardness and stickiness parameters. The instrumental hardness showed high correlation with sensory hardness, chewiness and overall quality (r = 0.72; r = 0.73; r = 0.79) and a negative correlation with sensory stickiness (r = −0.75). Applying principal component analysis, thermally processed rice samples were further classified based on the sensory and instrumental texture attributes.

Notes: This article describes the approach of the spectrum descriptive analysis (SDA) method to evaluate sensory properties of skin care products. The terminology for various lotions and creams was developed using SDA. A total of 26 attributes on five phases was developed with definitions and scales. Through discriminative, descriptive and scaling testing, 10 panelists were selected, and panel training was conducted until the panel grand standard deviation of the evaluated data of calibration samples showed less than 1.0. After the extensive training on sensory perceptions and scaling, the panelists evaluated the 26 attributes on 12 aqua-cream products. In the principal component analysis result of aqua-cream data, the first principal component (PC) was mainly related to oiliness, viscosity, adhesiveness and thickness on one side of the scale and transparency, wetness, coolness and spreadability on the other, with 40% of variance. The stickiness and gloss contributed greatly to the second PC with 30% of variance. The total amount of variance that was explained at the two PCs was 78%. In the biplot loadings of products and attributes, creams of K and L were identified by their higher degrees of wetness, spreadability and moisturization. They had lower degrees of stickiness, gloss and oiliness.

Notes: To determine the taste components of Cheddar cheese, we fractionated one mild Cheddar cheese and one aged Cheddar cheese by water extraction, freeze-drying and gel filtration. Salty, sour and umami were the three predominant tastes present in the fractions. Neither trigeminal sensations nor astringency was perceived. We used response surface methodology to reconstruct a mild Cheddar cheese taste and an aged Cheddar cheese taste in water. Less salt and less acid were needed to simulate the taste of mild Cheddar cheese, compared with aged Cheddar cheese. Our optimized water solutions (containing sodium chloride, lactic acid and monosodium glutamate) were as similar to the real cheese samples as were the water extracts of the standard cheeses. However, neither our optimized solutions nor the water extracts matched the taste of the actual cheeses.

Notes: A convolution integral is developed to evaluate transient, drilling speed–dependent discharge rates into a tunnel gradually excavated in a homogeneous infinite aquifer. Comparison with the classical instantaneous-drilling evaluation commonly used in practice reveals drastically reduced early-time discharge rates, higher maximum rates, and similar long-term rates. Dimensionless-type curves are provided to help assess total discharge sensitivity to drilling time and predict safer maximum flow rates.

Notes: Conceptual geological models based on geophysical data can elucidate aquifer architecture and heterogeneity at meter and smaller scales, which can lead to better predictions of preferential flow pathways. The macrodispersion experiment (MADE) site, with 〉2000 measurements of hydraulic conductivity obtained and three tracer tests conducted, serves as an ideal natural laboratory for examining relationships between subsurface flow characteristics and geophysical attributes in fluvial aquifers. The spatial variation of hydraulic conductivity measurements indicates a large degree of site heterogeneity. To evaluate the usefulness of geophysical methods for better delineating fluvial aquifer heterogeneities and distribution of preferential flow paths, a surface grid of two-dimensional ground penetrating radar (GPR) and direct current (DC) resistivity data were collected. A geological model was developed from these data that delineate four stratigraphic units with distinct electrical and radar properties including (from top to bottom) (1) a meandering fluvial system (MFS); (2) a braided fluvial system (BFS); (3) fine-grained sands; and (4) a clay-rich interval. A paleochannel, inferred by other authors to affect flow, was mapped in the MFS with both DC resistivity and GPR data. The channel is 2 to 4 m deep and, based on resistivity values, is predominantly filled with clay and silt. Comparing previously collected hydraulic conductivity measurements and tracer-plume migration patterns to the geological model indicates that flow primarily occurs in the BFS and that the channel mapped in the MFS has no influence on plume migration patterns.

Notes: Discrete-fracture and dual-porosity models are infrequently used to simulate solute transport through fractured unconsolidated deposits, despite their more common application in fractured rock where distinct flow regimes are hypothesized. In this study, we apply four fracture transport models—the mobile-immobile model (MIM), parallel-plate discrete-fracture model (PDFM), and stochastic and deterministic discrete-fracture models (DFMs)—to demonstrate their utility for simulating solute transport through fractured till. Model results were compared to breakthrough curves (BTCs) for the conservative tracers potassium bromide (KBr), pentafluorobenzoic acid (PFBA), and 1,4-piperazinediethanesulfonic acid (PIPES) in a large-diameter column of fractured till. Input parameters were determined from independent field and laboratory methods. Predictions of Br BTCs were not significantly different among models; however, the stochastic and deterministic DFMs were more accurate than the MIM or PDFM when predicting PFBA and PIPES BTCs. DFMs may be more applicable than the MIM for tracers with small effective diffusion coefficients (De) or for short timescales due to differences in how these models simulate diffusion or incorporate heterogeneities by their fracture networks. At large scales of investigation, the more computationally efficient MIM and PDFM may be more practical to implement than the three-dimensional DFMs, or a combination of model approaches could be employed. Regardless of the modeling approach used, fractures should be incorporated routinely into solute transport models in glaciated terrain.

Notes: System dynamics is a computer-aided approach to evaluating the interrelationships of different components and activities within complex systems. Recently, system dynamics models have been developed in areas such as policy design, biological and medical modeling, energy and the environmental analysis, and in various other areas in the natural and social sciences. The Idaho National Engineering and Environmental Laboratory, a multipurpose national laboratory managed by the Department of Energy, has developed a system dynamics model in order to evaluate its utility for modeling large complex hydrological systems. We modeled the Bear River basin, a transboundary basin that includes portions of Idaho, Utah, and Wyoming. We found that system dynamics modeling is very useful for integrating surface water and ground water data and for simulating the interactions between these sources within a given basin. In addition, we also found that system dynamics modeling is useful for integrating complex hydrologic data with other information (e.g., policy, regulatory, and management criteria) to produce a decision support system. Such decision support systems can allow managers and stakeholders to better visualize the key hydrologic elements and management constraints in the basin, which enables them to better understand the system via the simulation of multiple “what-if” scenarios. Although system dynamics models can be developed to conduct traditional hydraulic/hydrologic surface water or ground water modeling, we believe that their strength lies in their ability to quickly evaluate trends and cause-effect relationships in large-scale hydrological systems, for integrating disparate data, for incorporating output from traditional hydraulic/hydrologic models, and for integration of interdisciplinary data, information, and criteria to support better management decisions.

Notes: This paper presents a general model of optimal water management for a transboundary aquifer under three different management approaches: cooperative, noncooperative, and myopic. Comparing the results from the approaches, we find the cooperative solution, where a single management plan is executed for all parts of the aquifer, results in the highest level of net social welfare, followed by the noncooperative and then the myopic. The trade-offs we find for the higher levels of welfare are lower use levels in the earlier periods. We present a short discussion of factors that can increase the inefficiencies of the models and suggest directions for future research.

Notes: The goal for any property rights system is to achieve equity, efficiency, and certainty. Trying to achieve these goals for ground water is difficult because a ground water right is not exclusive. To make matters more complicated, ground water is often under the jurisdiction of more than one political unit. The result is transboundary conflicts. Two critical elements must be included in any system of ground water rights. The system must define how the ground water can be used and define the relationships that each user and each use has with the other users and uses in the system. Unfortunately, these relationships are seldom completely defined and are made more complex by the transboundary scales at which they operate. As ground water moves horizontally across boundaries, different users or different jurisdictions have sequential control, creating conflicts between the first users and subsequent ones. Other problems occur because of vertical relationships, with more than one person or entity having control over ground water at the same time. This simultaneous exercise of authority can create conflicts between an individual who possesses a right to use ground water and a state or federal agency that regulates the same water. Transboundary conflicts occur at different scales and include conflicts between neighboring property owners as well as conflicts between countries. Scale, the property rights structure, and the nature of the relationship between users influence the way transboundary ground water conflicts are resolved.

Notes: In Europe, a long history of cooperation over transboundary rivers—most notably the Rhine and Danube rivers—exists. To help foster cooperation and communication vis-à-vis transboundary ground water, the United Nations Economic Commission for Europe (UNECE), as part of its ground water program, conducted a survey on transboundary aquifers in Europe. The survey produced 25 responses from 37 countries and identified 89 transboundary aquifers. Respondents reported on the degree of ground water use within their own boundaries, transboundary aspects (agreements, joint commissions, etc.) of ground water, and transboundary aquifers themselves. The inventory proved useful, but a number of problems were identified: different map scales and symbols, difficulty in identifying transboundary aquifers, inconsistent labeling of aquifers, and data discrepancies. The UNECE ground water program also drafted guidelines for monitoring and assessment of transboundary ground water. These guidelines are not legally binding but have been adopted by 25 countries, deal mainly with monitoring and assessment, and are being implemented through a number of pilot projects. Other organizations—the United Nations Scientific, Educational and Cultural Organization, the Food and Agriculture Organization, the International Association of Hydrogeologists, and the European Union—are all supporting the investigation of transboundary aquifers in an effort to facilitate data sharing and coordinated management of these valuable resources.

Notes: More than one-half of the world's population is dependent on ground water for everyday uses such as drinking, cooking, and hygiene. In fact, it is the most extracted natural resource in the world. As a result of growing populations and expanding economies, many aquifers today are being depleted while others are being contaminated. Notwithstanding the world's considerable reliance on this resource, ground water resources have long received only secondary attention as compared to surface water, especially among legislatures and policymakers. Today, while there are hundreds of treaties governing transboundary rivers and lakes, there is only one international agreement that directly addresses a transboundary aquifer. Given that many of the aquifers on which humanity so heavily relies cross international borders, there is a considerable gap in the sound management, allocation, and protection of such resources. In order to prevent future disputes over transboundary aquifers and to maximize the beneficial use of this resource, international law must be clarified as it applies to transboundary ground water resources. Moreover, it must be defined with a firm basis in sound scientific understanding. In this paper we offer six conceptual models is which ground water resources can have transboudary consequences. The models are intended to help in assessing the applicability and scientific soundness of existing and proposed rules governing transboundary ground water resources. In addition, we consider the development of international law as it applies to ground water resources and make recommendations based on the models and principles of hydrogeology. The objective is the development of clear, logical, and science-based norms of state conducts as they relate to aquifers that traverse political boundaries.

Notes: A tracer test in a carbonate aquifer is analyzed using the method of moments and two analytical advection-dispersion models (ADMs) as well as a numerical model. The numerical model is a coupled continuum-pipe flow and transport model that accounts for two different flow components in karstified carbonate aquifers, i.e., rapid and often turbulent conduit flow and Darcian flow in the fissured porous rock. All techniques employed provide reasonable fits to the tracer breakthrough curve (TBC) measured at a spring. The resulting parameter estimates are compared to investigate how each conceptual model of flow and transport processes that forms the basis of the analyses affects the interpretation of the tracer test. Numerical modeling results suggest that the method of moments and the analytical ADMs tend to overestimate the conduit volume because part of the water discharged at the spring is wrongly attributed to the conduit system if flow in the fissured porous rock is ignored. In addition, numerical modeling suggests that mixing of the two flow components accounts for part of the dispersion apparent in the measured TBC, while the remaining part can be attributed to Taylor dispersion. These processes, however, cannot reasonably explain the tail of the TBC. Instead, retention in immobile-fluid regions as included in a nonequilibrium ADM provides a possible explanation.

Notes: Previous studies have used flowmeters in environments that are within the expectations of their published ranges. Electromagnetic flowmeters have a published range from 0.1 to 79.0 m/min, and impeller flowmeters have a published range from 1.2 to 61.0 m/min. Velocity-log data collected in five long-screened production wells in the Pleasant Valley area of southern California showed that (1) electromagnetic flowmeter results were comparable within ±2% to results obtained using an impeller flowmeter for comparable depths; (2) the measured velocities from the electromagnetic flowmeter were up to 36% greater than the published maximum range; and (3) both data sets, collected without the use of centralizers or flow diverters, produced comparable and interpretable results. Although either method is acceptable for measuring wellbore velocities and the distribution of flow, the electromagnetic flowmeter enables collection of data over a now greater range of flows. In addition, changes in fluid temperature and fluid resistivity, collected as part of the electromagnetic flowmeter log, are useful in the identification of flow and hydrogeologic interpretation.

Notes: While the discussion of model uncertainty has centered on spatial heterogeneity, it is possible that ground water models have not enjoyed much success as predictive tools often because the sources that were eventually imposed in the field differed from those represented in the simulations. This is because deterministic prediction of future conditions is often inaccurate due to the random nature of contaminant sources, in terms of their timing, location, and magnitude. This paper presents a stochastic framework for accommodating random contaminant sources in conventional, deterministic advection-dispersion transport models. The contaminant sources are first classified into two types: those occurring continuously with a deterministic component and random variations and those occurring randomly at instantaneous discrete-time intervals. For the first type, the governing partial differential equation (PDE) is replaced by a stochastic PDE. The random variations are modeled by Gaussian noise or Brownian motion, and the solution is obtained by using Ito's integration technique. For the second type, Markovian analysis is used for discrete-time contamination events. Both approaches use a deterministic transport model to generate response functions at any observation location and time. The response functions are then integrated to yield probabilistic description of contaminant transport, from which key statistical properties such as mean, standard deviation, and confidence interval can be drawn.

Notes: A model of porosity development has been developed to investigate general relationships between simple fracture aperture growth laws and fracture porosity in evolved fracture arrays in aquifers. The growth of fracture apertures in two-dimensional orthogonal arrays with initially spatially uncorrelated lognormal aperture distributions has been studied, where aperture growth rate is proportional to an exponent of the flow rate through each fracture. The evolved arrays show geometrical phase changes as a function of the aperture growth rate exponent, e, and the standard deviation of the initial aperture distribution, σz. Low values of e and σz lead to bimodal aperture distributions, where apertures parallel to flow are preferentially enlarged. At moderate values of e and σz, there is a transition to a regime of more complex geometries consisting of networks of channel-like structures of preferentially enlarged apertures. At larger values of e, array-spanning channel-like paths of preferentially enlarged apertures develop, where the tortuosity of the channel-like paths is a linear function of σz. Following an initial growth phase, during which dynamically stable aperture configurations develop, arrays undergo simple amplification. The geometry of the evolved aperture fields is diverse and they can be highly complex; consequently, parameterization and prediction of their evolution in terms of the initial aperture distributions and growth rate laws is not trivial.

Notes: A field-scale demonstration project was conducted to evaluate the capability of eastern cottonwood trees (Populus deltoides) to attenuate trichloroethene (TCE) contamination of ground water. By the middle of the sixth growing season, trees planted where depth to water was 〈3 m delivered enough dissolved organic carbon to the underlying aquifer to lower dissolved oxygen concentrations, to create iron-reducing conditions along the plume centerline and sulfate-reducing or methanogenic conditions in localized areas, and to initiate in situ reductive dechlorination of TCE. Apparent biodegradation rate constants for TCE along the centerline of the plume beneath the phytoremediation system increased from 0.0002/d to 0.02/d during the first six growing seasons. The corresponding increase in natural attenuation capacity of the aquifer along the plume centerline, from 0.0004/m to 0.024/m, is associated with a potential decrease in plume-stabilization distance from 9680 to 160 m. Demonstration results provide insight into the amount of vegetation and time that may be needed to achieve cleanup objectives at the field scale.

Notes: The hydraulic conductivity (K) variation has important ramifications for ground water flow and the transport of contaminants in ground water. The delineation of the nature of that variation can be critical to complete characterization of a site and the planning of effective and efficient remedial measures. Site-specific features (such as high-conductivity zones) need to be quantified. Our alluvial field site in the Kansas River valley exhibits spatial variability, very high conductivities, and nonlinear behavior for slug tests in the sand and gravel aquifer. High-resolution, multilevel slug tests have been performed in a number of wells that are fully screened. A general nonlinear model based on the Navier-Stokes equation, nonlinear frictional loss, non-Darcian flow, acceleration effects, radius changes in the wellbore, and a Hvorslev model for the aquifer has been used to analyze the data, employing an automated processing system that runs within the Excel spreadsheet program. It is concluded that slug tests can provide the necessary data to identify the nature of both horizontal and vertical K variation in an aquifer and that improved delineation or higher resolution of K structure is possible with shorter test intervals. The gradation into zones of higher conductivity is sharper than seen previously, and the maximum conductivity observed is greater than previously measured. However, data from this project indicate that well development, the presence of fines, and the antecedent history of the well are important interrelated factors in regard to slug-test response and can prevent obtaining consistent results in some cases.

Notes: To improve understanding of property measurements in heterogeneous media, an energy-based weighting function concept is developed. In (assumed) homogeneous media, the instrument spatial weighting function (ISWF) depends only on the energy dissipation distribution set up by the measurement procedure and it reduces to simply inverse sample volume (uniform weighting) for 1-D parallel flow case (ideal permeameter). For 1-D transient flow in homogeneous media, such as with slug tests, the ISWF varies with position and time, with 95% of the total weighting contained within 115 well radii, even late in the test. In the heterogeneous case, the determination of the ISWF is connected to the problem of determining an equivalent hydraulic conductivity (K), where the criterion for equivalence is based on equal energy dissipation rate rather than equal volume discharge. The discharge-based equivalent K (KE) and the energy-based equivalent K in heterogeneous media (Keh) are not equal in general, with Keh typically above the nodal arithmetic mean K. The possibly more fundamental problem is that as one makes K measurements in heterogeneous media at different locations or on different cores of heterogeneous materials, the ISWF will be heterogeneity dependent, implying that the averaging process resulting in the equivalent K value also varies with position. If the testing procedure is transient, then the averaging process varies with time. This suggests a fundamental ambiguity in the interpretation of hydraulic conductivity measurements in heterogeneous media that may impact how we approach modeling and prediction in a practical sense (Molz 2003). Further research is suggested.

Notes: At a number of sites, a plume of methyl tert-butyl ether (MTBE) in ground water has dived below the screen of conventional monitoring wells and escaped detection. Techniques are needed to predict the vertical extent of MTBE in an aquifer. Two techniques that are emerging in the site characterization market are electrical conductivity logging and pneumatic slug testing performed in temporary push wells. These techniques were evaluated at a diving plume of MTBE in the aquifer that supplies water to the village of East Alton, Illinois. The plume stayed near the water table for the first 100 m from the potential sources and then dived below conventional monitoring over the next 100 m. At the location where the MTBE plume dived, the depth to water was 9.1 m below land surface. The first 10 m of material below the water table had an electrical conductivity near 100 mS/m, indicating silts and clays. An electrical conductivity near 25 mS/m, indicating sands or gravels, was encountered at a depth of 10.6 m below the water table, and the sands and gravel extended to a depth of at least 15.2 m below the water table. Pneumatic slug tests measured low hydraulic conductivity in the interval of silt and clay (0.34 and 0.012 m/d) and higher hydraulic conductivity in the interval with sands and gravels (12.5, 11.6, and 11.3 m/d). Ground water with the highest concentration of MTBE was produced just below the contact between the silt and clay and the sands and gravel.

Notes: Steam injected below the water table tends to move upward because of buoyancy. This limits the horizontal steam zone development, which determines the optimal spacing between injection wells. In this study, observations indicating steam override at a full-scale remediation of an unconfined aquifer are analyzed by numerical modeling using the code T2VOC. A simplified three-dimensional (3D) numerical model is set up, which qualitatively shows the same mechanisms as observed at the site. By means of the model, it is found that it will be possible to achieve a larger horizontal extent of the steam zone in a layered geology compared to the homogeneous case. In the homogeneous case, the steam injection rate increases dramatically when the injection pressure is increased, which is necessary to achieve a larger horizontal development. The development of the steam zone under unconfined conditions is found to be a complex function of the geologic layering, the water table at steady-state extraction, and the injection/extraction system. Because of this complexity, it will be difficult to predict steam behavior without site-specific 3D numerical modeling.

Notes: This work describes the integration of data acquisition (DAQ) hardware and software for the purpose of acquiring not only data but real-time transport model parameter estimates in the context of subsurface flow and transport problems. Integrated DAQ parameter estimation systems can be used to reduce data storage requirements, trigger event recognition and more detailed sampling actions, and otherwise enhance remote monitoring capabilities. The contaminant transport problem is posed here as the analogous heat transfer problem in a three-dimensional, intermediate-scale physical aquifer model. A constant source of warm water is fed into a sandy aquifer undergoing steady, unidirectional flow. The spatial distribution of temperature in the medium is monitored over time using 17 thermocouples embedded in the medium. These sensors log temperatures via conventional analog-to-digital conversion hardware driven by commercially available DAQ software (LabVIEW™). Parameter estimation routines programmed in MATLAB™-based M-files are embedded in the LabVIEW DAQ routine and access parameter estimation libraries, such as the descent method employed here, via the Internet. The integrated DAQ parameter estimation system is demonstrated for the estimation of (1) the thermal dispersion coefficients (analogous to mass dispersion coefficients), given a known heat source; and (2) the location of a heat source, given known thermal dispersion coefficients. In both cases, the parameter estimation procedure is executed repeatedly as the data are acquired. For the case of source location, the effect of the number of sensors on the parameter estimation procedure is also demonstrated. Reasonable parameter estimates are provided rapidly during both the transient and steady-state phases of the experiments, with accuracy increasing with time and with the number of observations employed.

Notes: Herbicide and herbicide degradate compounds were measured in tile drains, monitoring wells, domestic wells, and in the receiving stream at a farm in south-central Michigan, in which corn, soybeans, and livestock are the major products. Immunoassay screens of two herbicide groups (triazines and alachlor) in 2000 showed a decrease in the number of detections from June to September, after the well-known spring flush, of 48% to 26% for alachlor and 62% to 22% for the triazines. Gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry analyses of 2001 samples documented a fall flush as well, mobilizing relatively high levels of both parent and degradate compounds to the tile drain system. The compounds included both metolachlor and atrazine, which were applied on the farm earlier that year, as well as the degradates of alachlor, which had not been applied on the farm for several years. In four tile drain samples, metolachlor was detected at concentrations ranging from 18 to 25 μg/L, whereas atrazine ranged from nondetect to 2.25 μg/L. Contrary to previous studies, metolachlor concentrations were higher than metolachlor ethane sulfonic acid, by a factor of 3 to 7. The high soil permeability, high water table, and shallow screened intervals of monitoring wells directly below the point of application may explain the lesser degree of breakdown at the point of sampling. Although most detections were below maximum contaminant level or health advisory levels, the unknown effects of degradates and the aggregate levels of compounds measured in many samples may pose higher health risks than for individual compounds.

Notes: Monitoring data collected over a 6-year period show that a plume of chlorinated ethene–contaminated ground water has contracted significantly following treatment of the contaminant source area using in situ oxidation. Prior to treatment (1998), concentrations of perchloroethene (PCE) exceeded 4500 μg/L in a contaminant source area associated with a municipal landfill in Kings Bay, Georgia. The plume emanating from this source area was characterized by vinyl chloride (VC) concentrations exceeding 800 μg/L. In situ oxidation using Fenton's reagent lowered PCE concentrations in the source area below 100 μg/L, and PCE concentrations have not rebounded above this level since treatment. In the 6 years following treatment, VC concentrations in the plume have decreased significantly. These concentration declines can be attributed to the movement of Fenton's reagent–treated water downgradient through the system, the cessation of a previously installed pump-and-treat system, and the significant natural attenuation capacity of this anoxic aquifer. While in situ oxidation briefly decreased the abundance and activity of microorganisms in the source area, this activity rebounded in 〈6 months. Nevertheless, the shift from sulfate-reducing to Fe(III)-reducing conditions induced by Fenton's treatment may have decreased the efficiency of reductive dechlorination in the injection zone. The results of this study indicate that source-area removal actions, particularly when applied to ground water systems that have significant natural attenuation capacity, can be effective in decreasing the areal extent and contaminant concentrations of chlorinated ethene plumes.

Notes: Two small-diameter (≤0.5-inch/13-mm O.D.) bladder pumps were evaluated under the U.S. EPA Environmental Technology Verification Program to assess their ability to provide representative water quality samples for several volatile organic compounds (VOCs) and major element cations. Both a pneumatic bladder pump (PnBP) and a newly designed mechanical bladder pump (MBP) were evaluated. Since the MBP does not require compressed air to operate, the field logistics are simplified and cost of conducting low-flow sampling can be reduced. Replicate samples were collected from an above-ground standpipe spiked with selected VOCs and cations. Low-flow sampling protocol was followed during collection of replicate samples from six direct push (DP)–installed monitoring wells at Tyndall Air Force Base, Florida. Simple statistical methods are used to evaluate the sample quality provided by the pumps as compared to reference samples. F-tests are used to evaluate pump sample precision, and t-tests are applied to evaluate comparability of the pump sample results to the colocated reference or port sample results. Statistical analysis reveals that the samples collected with the pumps provide precision comparable to that observed in the reference samples. Significantly greater variability was observed between the pump and reference samples collected from the DP wells than was observed during the standpipe trials. The results and statistics from the trials at the standpipe indicate that both the PnBP and MBP provide water quality samples that are comparable to the reference samples, for the analytes investigated.

Notes: Survival of Listeria monocytogenes in chorizos (Mexican-style sausages) was modeled in relation to initial water activity (aw0) and storage conditions using the Weibull cumulative distribution function. Twenty survival curves were generated from chorizos formulated at aw0 = 0.85–0.97 then stored under four temperature (T) and air inflow velocity (F) conditions. The Weibull model parameters (α and β) were determined for every curve. Predicted survival curves agreed with experimental curves with R2 = 0.945–0.992. Regression models (R2 = 0.981–0.984) were developed to relate α and β to operating conditions. The times to one- and two-log reduction in count (t1D and t2D) were derived from the Weibull model in terms of α and β. A parametric study revealed that L. monocytogenes survival was most sensitive to aw0 between 0.90 and 0.95. The inactivation of L. monocytogenes could be maximized with higher T and lower aw0; however, F did not significantly influence survival.

Notes: Food safety experts have a key role in constructing food risk messages and thus their perceptions will influence how food risk issues are communicated to the public. This research examined the perceptions of food safety experts regarding public understanding of food risk issues and food risk messages on the island of Ireland. It also looked into expert views of the barriers to effective food risk communication and how to improve food risk messages. One hundred and forty-three experts, working in areas related to food safety, completed an online questionnaire. Questionnaire and statement design was guided by the results of four in-depth interviews with food safety experts. The findings indicate that most experts surveyed have little confidence in the public's understanding of food risk issues, their assessment of food risks, their ability to deal with scientific information and their food safety practices. Experts are of the view that the public under-assesses the risk associated with some microbiological hazards and over-assesses the risk associated with other hazards such as genetically modified organisms (GMOs) and bovine spongiform encephalopathy. The opinion of experts with regard to GMOs is not supported by previous consumer research. Experts noted that the level of education and age were important determinants for the level of understanding of food risk issues and messages. Experts were of the view that early intervention via school curricula was the best method to improve public understanding of food risk messages in the long term. Furthermore, experts are of the view that the media have the ability to improve awareness and knowledge about food risk issues but believe that the media tend to communicate information that is misleading. The majority of experts also believe that they should communicate uncertainty but are not confident that the public is able to cope with this uncertainty. Many of the experts also indicated a desire for training on how to interact with the media. The results may be used by those experts who are involved in the construction of food risk messages to improve the design and communication of food risk messages.

Notes: The aim of this research was to investigate the potential relationship, if any, between the acquisition/possession of antibiotic resistance genes in strains of Salmonella and its resistance to heat stress. Chicken pieces were inoculated with antibiotic sensitive (AS) strains of S. Enteritidis and S. Typhimurium, its laboratory-acquired antibiotic-resistant (AR) mutant strains (nalidixic acid and streptomycin), or a multiresistant strain of S. Typhimurium DT104. Half of these samples were heat-shocked (48C for 30 min) and all were heat-challenged at 55C for up to 30 min. Samples were then plated on xylose lysine desoxycholate (XLD) and tryptone soya agar (TSA) overpoured with XLD. Heat-shocked cultures of S. Typhimurium DT104 had significantly higher D-values (the time required for a 1 log reduction in the number of bacteria) than their non-heat-shocked counterparts (P 〈 0.05). No significant differences were observed between AR and their AS. However, the D-values for S. Typhimurium DT104 were significantly higher than the D-values for S. Typhimurium (AS) and S. Enteritidis (AS) (P 〈 0.05). This study concluded that laboratory-acquired antibiotic-resistant mutation did not affect heat resistance of the Salmonella strains studied and suggested a potential link between multiantibiotic resistance and heat resistance in S. Typhimurium DT104.

Notes: Pediococcus pentosaceous DT10, isolated from ready-to-eat fish products, produced a bacteriocin active against Gram-positive bacteria, many of which are associated with food spoilage and food-related health hazards. The bacteriocin, named pediocin DT10, was partially purified and was observed to kill sensitive Leuconostoc mesenteroides cells by acting on their cytoplasmic membrane. Exposure of cell suspensions of L. mesenteroides to pediocin DT10 produced cell-viability loss, as shown by the reduction in colony-forming units after treatment. The activity of pediocin DT10 against L. mesenteroides cells was bactericidal in nature, and also induced an important efflux of intracellular material. The transmission electron microscopy of ultrathin sections of L. mesenteroides cells confirmed the way pediocin DT10 causes lysis of the sensitive L. mesenteroides cells.

Notes: All Gram-negative bacteria tested were normally resistant to the bactericidal action of pediocin P of Pediococcus pentosaceous Pep1, which had been isolated from vacuum-packaged sausages. However, when they were subjected to sublethal stress (exposure to physical and chemical stresses such as freezing, heating and acid treatment) and were treated with pediocin P, gram-negative bacterial cells that were normally resistant to pediocin P developed sensitivity to it and pediocin P reduced the viability of bacterial cells surviving sublethal stresses, although the extent of reduction varied with strain and type of treatment. When the combined effect of ethylenediaminetetraacetic acid (EDTA), sublethal heat and pediocin P was studied by adding EDTA and pediocin P to cell suspensions right before heating them, there was a considerable reduction in the number of viable cells, even at the lowest concentration of pediocin P tested. The results of our preliminary studies showed that sublethal injury can make the gram-negative bacterial cells sensitive to pediocin P.

Notes: The ability of two strains of Salmonella to form biofilms on whole cantaloupe melons was investigated. Ten microliters of bacterial suspensions was spot-inoculated onto cantaloupe melon rinds in pre-marked areas, and the cantaloupe melons were held at either 10 or 20C. Biofilm formation was monitored using scanning electron microscopy on excised portions of the cantaloupe melon rind at 2, 24, 48, 72 and 144 h postinoculation. Micrographs indicated that biofilm formation occurred rapidly following introduction of cells (2 h at 20C) onto the cantaloupe melon rind. A fibrillar material was visible after just 2 h at 20C, and cells were embedded in extracellular polymeric material after 24 h at either temperature. These results indicate that a human pathogen is capable of forming a biofilm on plant tissue and that biofilm formation may be responsible for the increased recalcitrance of bacteria to aqueous sanitizers.

Notes: The differences in attachment and penetration ability of Campylobacter jejuni were determined by analyzing C. jejuni isolates obtained from chicken carcasses and from humans exhibiting symptoms of campylobacteriosis. INT 407 cells, a human cell line originating from the jejunal/ileal region, were used as the in vitro model, and attachment and penetration abilities were evaluated for each isolate. There were no significant differences between the attachment and penetration abilities of chicken isolates and human isolates (HUMN). In addition, a wide range of attachment and penetration abilities was found for the isolates, with many of the HUMN possessing low attachment and penetration abilities. These data indicate that C. jejuni attachment and penetration into the human ileal and jejunal regions may not be primary virulence factors and may only be important in causing more acute symptoms.

Notes: Storage experiments were conducted to follow the behavior of Listeria monocytogenes and Escherichia coli O157:H7, deliberately inoculated on fresh-cut cactus-pear fruits before packaging under modified and control atmosphere and stored at four different temperatures (4, 8, 12 and 20C). L. monocytogenes was able to proliferate during storage at different temperature both in control and modified atmosphere. By comparing the sanitary-risk values with those of shelf life, it is possible to conclude that the storage of cactus-pear samples at temperatures greater than 4C, both in control and in modified atmospheres, could lead to a significant health-time risk, and that this is strictly affected by temperature. E. coli O157:H7 was able to proliferate only in the sample stored at 4 and 8C in both package atmospheres. On the contrary, this species was completely suppressed at the higher temperatures. In our study, E. coli O157:H7 appeared to be much less suited for survival on the surface of the fruit than L. monocytogenes.

Notes: Antimicrobial resistance was determined for 73 isolates of Salmonella enteritidis isolated from foods involved in human foodborne outbreaks that occurred in the South of Brazil, from 1999 to 2000. The isolates were individually tested against 10 antimicrobial agents using a disc diffusion method. Most isolates were susceptible to all drugs tested. No S. enteritidis isolates were resistant to sulfamethoxazole/trimethoprim or chloramphenicol. The predominant resistance observed was to streptomycin (S) (37%), gentamicin (GEN) (13.7%) and nalidixic acid (NAL) (13.7%), while intermediate resistance was observed most often for tetracycline (53.4%), neomycin (NEO) (30.1%) and GEN (15.1%). Resistance was verified in 40 isolates (54%), which were grouped in 15 different patterns. Multiple resistance was presented in 17 (23%) of the isolates, and one isolate exhibited resistance to four drugs (NEO, kanamycin, S and NAL), demonstrating the involvement of multiresistant S. enteritidis strains with foodborne outbreaks.

Notes: Fresh, different meat types and offal were examined for the occurrence of Aeromonas species by the direct-plating and enrichment methods. The enrichment method (coefficient of variation = 15.1%) enhanced the recovery of Aeromonas species. The major Aeromonas species identified were A. sobria (67.3%) and A. hydrophila (21.2%). Other species occurred in minor proportions and were A. caviae, A. proteolytica and A. salmonicida. Out of the 52 isolates, 50 were motile species except two which were not motile and identified as the species A. proteolytica. Sixteen motile species occurred in cow, 18 in goat and 16 in lamb. The motile species and the two nonmotile species were hemolytic. They were all sensitive to chloramphenicol (30 mg) and resistant to ampicillin (10 mg). The nonmotile A. proteolytica were all resistant to tetracycline. Aeromonas caviae, A. salmonicida, A. hydrophila and A. sobria were killed after exposure to 50C (decimal reduction time, D10 = 30 s). Aeromonads are unlikely to pose a public health problem in Nigeria where meat undergoes prolonged cooking. Meat is a possible factor in the epidemiology of Aeromonas-associated gastroenteritis in man.

Notes: Campylobacter jejuni is a leading cause of human gastroenteritis. Using a tissue culture system, researchers have found that spiral forms of C. jejuni are more pathogenic than coccoid forms of the same strain. The objective of this research was to investigate genomic changes associated with the dimorphism in C. jejuni using pulsed-field gel electrophoresis (PFGE) and sequencing of flaA gene of C. jejuni isolated from chicken carcasses and human stool samples. C. jejuni isolates were cultured for 18 h (spiral form) and 72 h (coccoid form). PFGE profiles of both forms of C. jejuni showed 100% genetic similarity. For sequence analysis of the flaA gene of C. jejuni, its short-variable region (SVR) was analyzed. For the two forms of the same isolate, the nucleic-acid sequences of the SVR of flaA showed 95–100% similarity. It is concluded that morphological dimorphism of C. jejuni was not associated with genetic changes as measured by the mentioned tests.

Notes: The Aerobic Plate Counts (APCs) of some Philippine ready-to-eat (RTE) foods from take-away premises were established for the first time within the context of using the information for the development of Philippine microbial guidelines for RTE foods. The calculated APCs for most of the RTE foods analyzed in the study were ≤ 10 5 cfu/unit of food sample. Among the reasons cited to explain higher APC values were: use of raw ingredients for the final product, temperature abuse during vending, inadequate cooking and use of leftovers. It was recommended that the generally acceptable microbial guideline value for APC of RTE foods set at 〈 105 cfu/unit be adapted locally until more precise microbial criteria for this food type could be developed through an appropriate scientific process.

Notes: Isolates from fermented foods were screened for antimicrobial activity against gram-negative bacteria. The most active isolate was identified as a Lactobacillus curvatus by biochemical analysis and ribotyping, and the isolate was designated as OSY-HJC6. Lactobacillus curvatus OSY-HJC6 was further tested for intracellular and extracellular production of antimicrobial agents. A reduction of 〉 8 log10 cfu/mL was observed when cell suspensions of Salmonella enterica serovar Enteritidis and Escherichia coli O157:H7 were treated with equal volumes of Lb. curvatus culture supernatant. Gram-positive bacteria were not sensitive to the culture supernatant, but antimicrobial activity was detected when the cell extract was tested against several gram-positive and gram-negative bacteria. Culture supernatant and cell extract retained the antimicrobial activity after heating at 60–100C for 10 min but not after protease treatment. The cell extract of Lb. curvatus retarded the growth of E. coli p220 in broth medium and food extracts (i.e., bacteriostatic action) but showed bactericidal activity against the bacterium in phosphate buffer.

Notes: A study was undertaken to assess the prevalence of Clostridium perfringens in meat and to characterize the isolates obtained in the study for virulence factors. A total of 211 meat samples of different animals (70 each of buffalo and goat and 71 of poultry) were screened and the highest occurrence of C. perfringens was observed in goat (91.4%) followed by poultry (70.4%) and buffalo (65.7%). Among the 116 isolates (buffalo-32, goat-37 and poultry-45) of C. perfringens screened for the presence of enterotoxin gene by PCR, 9.3, 32.4 and 15.5% isolates of buffalo, goat and poultry, respectively, were found to possess enterotoxin gene. Screening of 15 enterotoxin gene possessing isolates for verocytotoxicity revealed that 12 isolates exhibited cytopathic effect while 3 isolates did not show any cytopathic effect in spite of the presence of enterotoxin gene. A total of 115 C. perfringens isolates were screened for other virulence markers, i.e., lecithinase and hemolysin. The results revealed that the majority of the isolates expressed these activities. Antibiogram studies of C. perfringens isolates using 16 antibiotics displayed multidrug resistance. The isolates showed resistance to streptomycin, ceftazidime, colistin sulfate, cephalothin, ampicillin and gentamicin. Whereas 100% sensitivity to ciprofloxacin, ofloxacin and nitrofurantoin was seen, moderate sensitivity was observed with tetracycline and sulfatriad.

Notes: The pork tonsils are an important carrier of Salmonella, which could be involved in the contamination of pork products during the slaughter process. This paper reports a 23S rRNA fluorescent in situ hybridization (FISH) method used as a rapid screening tool for Salmonella detection in tonsils of slaughtered pigs and its comparison with the conventional culture method. As a rapid screening method, the FISH technique would reduce the high volume of negative samples that are routinely analyzed, indicating presumptive positive samples in a real and practical time. The use of a Sal3 probe allowed the rapid (7 h) Salmonella detection in 16 (34%) of 47 naturally contaminated tonsils, without pre-enrichment. Salmonella was isolated by the culture method in six samples that were also FISH-positive samples, and FISH failed to identify only one of the culture-positive samples. The results indicate the potential of this technique as a rapid screening method for detecting Salmonella in tonsils from pork slaughtered for consumption.

Notes: The antioxidant and antibacterial potentials of essential oils and acetone extracts of black pepper, cumin, black cumin and mace were carried out by different techniques. The antioxidative capacity of the essential oils and acetone extracts were evaluated against mustard oil by measuring peroxide and thibarbituric acid values at fixed intervals. In addition, their antioxidant potential was evaluated by 2, 2′-diphenyl-1-picrylhydracyl radical and conjugated diene assays. Their reducing power was determined with standards, which proved the strong antioxidant capacity of essential oils and extracts. The antioxidant activity of essential oils and extracts exerted by all the antioxidant assays can be compared with synthetic antioxidants such as butylated hydroxyanisole and butylated hydroxytoluene. The antibacterial activity was studied by disk diffusion and poison food methods. Black cumin essential oil showed complete zone of inhibition (P 〈 0.05) against tested bacterial strains of Staphylococcus aureus, Bacillus cereus and Bacillus subtilis at 2 and 6 µL level by disk diffusion method. Black cumin and black pepper extracts showed complete reduction of colonies against tested bacterial strains of S. aureus, B. cereus and B. subtilisat 5 and 10 µL level by poison food method. Poison food method exhibited good results for the tested essential oils and extracts. Essential oils of black pepper, cumin, black cumin and mace may be used to stabilize mustard oil after screening.

Notes: The objective of this investigation was to model the influence of the initial microbial concentration on the Escherichia coli resistance to chlorine. A suspension test was used to evaluate the antibacterial efficacy of chlorine. Chlorine doses ranged from 0.6 to 0.9 mL /L, from 0.3 to 0.7 m L /L, from 0.15 to 0.3 mL/L and from 0.1 to 0.2 mL /L when the initial microbial concentration was 1.2 × 108, 6 × 107, 6 × 106and 6 × 105 CFU/mL, respectively. In order to describe the survival curves of E. coli, a mathematical model based on a biphasic inactivation was used. Initial microbial concentration had a significant influence on the kinetics of inactivation and on the resistance of E. coli to chlorine. In order to obtain a good repeatability and reproducibility of the bacterial suspension test, the initial concentration of bacterial suspensions should be evaluated and standardized.

Notes: The growth and survival of Bacillus cereus, a known pathogen commonly found in cereals, during lactic acid fermentation of boza, a traditional Turkish cereal beverage, was studied. In the boza base inoculated with both the starter culture and B. cereus, the acidity developed to pH 2.6 and 0.8% titratable acidity after 72 h; the growth of B. cereus was reduced from 3.9 log cfu/mL to 1 log cfu/mL within 72 h. The control boza base to which starter was not added had a pH of 3, titratable acidity of 0.8%. The B. cereus in this boza base to which no starter culture was added dropped to 1 log cfu/mL after 72 h. No strains of lactic acid bacteria were found to produce bacteriocins antagonistic to B. cereus. Low pH and acidity were found to be the major factors inhibiting growth of B. cereus in boza.

Notes: Many divalent salts (e.g., calcium, iron, zinc), have important nutritional value and are used to fortify food or as dietary supplements. Sensory characterization of some divalent salts in aqueous solutions by untrained judges has been reported in the psychophysical literature, but formal sensory evaluation by trained panels is lacking. To provide this information, a trained descriptive panel evaluated the sensory characteristics of 10 divalent salts including ferrous sulfate, chloride and gluconate; calcium chloride, lactate and glycerophosphate; zinc sulfate and chloride; and magnesium sulfate and chloride. Among the compounds tested, iron compounds were highest in metallic taste; zinc compounds had higher astringency and a glutamate-like sensation; and bitterness was pronounced for magnesium and calcium salts. Bitterness was affected by the anion in ferrous and calcium salts. Results from the trained panelists were largely consistent with the psychophysical literature using untrained judges, but provided a more comprehensive set of oral sensory attributes.

Notes: Jaw movements during the act of biting were measured for seven subjects trained in descriptive analysis using an electrognathograph. The effectiveness of instrumental imitative tests performed at predefined and individual crosshead speeds (matching velocities measured in vivo) to predict the perception of hardness in 14 gelatin gels was assessed. For all seven subjects, the perception of hardness was adequately described by imitative instrumental tests performed with dental replicas of individual subjects (0.88 〈 R 〈 0.97). For some of the subjects, tests performed at crosshead speeds matching biting speeds improved the instrumental prediction of hardness, suggesting that biting velocity is an important aspect of the perception of hardness in food.

Notes: Response surface methodology was used to profile and characterize formulations of chocolate peanut spread. A constrained mixture design for 36 different formulations with varying peanut (P), chocolate (C) and sugar (S) was used. A processing variable, roast (R), was included where peanuts were roasted to light, medium and dark levels. A descriptive panel (n = 10) identified and rated 24 attributes, using 150-mm unstructured line scales. Regression analysis was performed and models were reduced. Models having R2 〉 0.70 were selected for prediction. Contour maps were constructed to: (1) visualize the effects of mixture components and roasting level and (2) characterize optimum formulations at light, medium and dark, which were determined as (30–49% P, 23–40% C and 21–31% S); (29–65% P, 0.9–41% C and 17–36% S) and (27–56% P, 19–45% C and 18–35% S), respectively, adding up to 100% of the mixture. Analyses of optimum and nonoptimum formulations and significant differences were not found between predicted and observed values for most attributes.

Notes: The impact of serving temperature on trained panel perception of Cheddar cheese flavor attributes was determined. Seven cheeses were selected to represent a range of age and flavor profiles. A descriptive sensory panel received 75 h training on 15 terms for cheese flavor attributes and basic tastes from a previously identified sensory lexicon for Cheddar cheese. Three serving temperatures were selected (5, 12, 21C). Cheeses were subsequently evaluated in quadruplicate by the panel at each serving temperature. Cheeses were differentiated on their flavor and taste attributes (P 〈 0.0001). Perception of sour taste intensity increased with serving temperature (P 〈 0.05). Other flavors and basic tastes did not exhibit a temperature effect or temperature by cheese interaction (P 〉 0.05). Panelists noted that cheese was more difficult to evaluate at 21C compared with 12 or 5C. Cheddar cheese serving temperature should not pose an issue for comparing descriptive sensory results from multiple locations.

Notes: Mixture design and pilot-plant scale processing protocol were developed to obtain the best chocolate-flavored peanut–soy beverage formulation. Twenty-eight formulations were evaluated for nutritional (lysine content), physical (viscosity [η], visual stability index [VSI]) and nine sensory (consumer liking) attributes. Lysine contents (mg/g protein) (44.1–57.1) were close to the reference (51.0) and in the desirable range observed for other peanut-based beverages. Higher viscosity indicated lower consumer liking, but lower viscosity resulted in lower VSI. Formulation ♯8 having 43.9% peanut, 36.3% soy protein isolate (SPI) and 19.8% chocolate syrup had the highest consumer liking and the best balance of physical properties (η = 41.5 mPa·s; VSI = 0.99). As compared to commercial chocolate milk (6 = slightly like to 7 = moderately like), it was rated higher for appearance (7.0), color (6.8) and sweetness (6.4). Two SPI formulations (♯6 and ♯7) and a soy flour formulation (♯14) were rated highest for aroma (6.2), color (7.0) and flavor (6.0), respectively.

Notes: This study explored consumer liking and perception of pork patties with an added functional health ingredient: shiitake (Lentinus edodes P.) mushroom powder. In addition, patties with and without sodium tripolyphosphate were tested. Both native Korean and U.S. consumers evaluated the products. Pork patties made with both phosphate and mushroom powder were found to be acceptable by Korean consumers, but increases in mushroom powder in patties with phosphate decreased acceptability for U.S. consumers. However, addition of mushroom powder to patties without phosphate increased acceptability for U.S. consumers, perhaps because it tended to increase texture acceptance and juiciness. Thus, addition of mushroom powder as a functional ingredient in pork patties, while possible, would require different formula modifications to appeal to consumers of differing nationalities.

Notes: Previous site-specific studies designed to assess the impacts of unsewered subdivisions on ground water quality have relied on upgradient monitoring wells or very limited background data to characterize conditions prior to development. In this study, an extensive monitoring program was designed to document ground water conditions prior to construction of a rural subdivision in south-central Wisconsin. Previous agricultural land use has impacted ground water quality; concentrations of chloride, nitrate-nitrogen, and atrazine ranged from below the level of detection to 296 mg/L, 36 mg/L, and 0.8 μg/L, respectively, and were highly variable from well to well and through time. Seasonal variations in recharge, surface topography, aquifer heterogeneities, surficial loading patterns, and well casing depth explain observed variations in ground water chemistry. This variability would not have been detected if background conditions were determined from only a few monitoring wells or inferred from wells located upgradient of the subdivision site. This project demonstrates the importance of characterizing both ground water quality and chemical variability prior to land-use change to detect any changes once homes are constructed.

Notes: From the mid-1940s through the 1980s, large volumes of waste water were discharged at the Hanford Site in southeastern Washington State, causing a large-scale rise (〉20 m) in the water table. When waste water discharges ceased in 1988, ground water mounds began to dissipate. This caused a large number of wells to go dry and has made it difficult to monitor contaminant plume migration. To identify monitoring wells that will need replacement, a methodology has been developed using a first-order uncertainty analysis with UCODE, a nonlinear parameter estimation code. Using a three-dimensional, finite-element ground water flow code, key parameters were identified by calibrating to historical hydraulic head data. Results from the calibration period were then used to check model predictions by comparing monitoring wells’ wet/dry status with field data. This status was analyzed using a methodology that incorporated the 0.3 cumulative probability derived from the confidence and prediction intervals. For comparison, a nonphysically based trend model was also used as a predictor of wells’ wet/dry status. Although the numerical model outperformed the trend model, for both models, the central value of the intervals was a better predictor of a wet well status. The prediction interval, however, was more successful at identifying dry wells. Predictions made through the year 2048 indicated that 46% of the wells in the monitoring well network are likely to go dry in areas near the river and where the ground water mound is dissipating.

Notes: A method is proposed to estimate the uncertainty of the location of pathlines in two-dimensional, steady-state confined or unconfined flow in aquifers due to the uncertainty of the spatially variable unconditional hydraulic conductivity or transmissivity field. The method is based on concepts of the semianalytical first-order theory given in Stauffer et al. (2002, 2004), which allows estimates of the lateral second moment (variance) of the location of a moving particle. However, this method is reformulated in order to account for nonuniform recharge and nonuniform aquifer thickness. One prominent application is the uncertainty estimation of the catchment of a pumping well by considering the boundary pathlines starting at a stagnation point. In this method, the advective transport of particles is considered, based on the velocity field. In the case of a well catchment, backtracking is applied by using the reversed velocity field. Spatial variability of hydraulic conductivity or transmissivity is considered by taking into account an isotropic exponential covariance function of log-transformed values with parameters describing the variance and correlation length. The method allows postprocessing of results from ground water models with respect to uncertainty estimation. The code PPPath, which was developed for this purpose, provides a postprocessing of pathline computations under PMWIN, which is based on MODFLOW. In order to test the methodology, it was applied to results from Monte Carlo simulations for catchments of pumping wells. The results correspond well. Practical applications illustrate the use of the method in aquifers.

Notes: Extremely alkaline ground water has been found underneath many shuttered steel mills and slag dumps and has been an impediment to the cleanup and economic redevelopment of these sites because little is known about the geochemistry. A large number of these sites occur in the Lake Calumet region of Chicago, Illinois, where large-scale infilling of the wetlands with steel slag has created an aquifer with pH values as high as 12.8. To understand the geochemistry of the alkaline ground water system, we analyzed samples of ground water and the associated slag and weathering products from four sites. We also considered several potential remediation schemes to lower the pH and toxicity of the water. The principal cause of the alkaline conditions is the weathering of calcium silicates within the slag. The resulting ground water at most of the sites is dominated by Ca2+ and OH− in equilibrium with Ca(OH)2. Where the alkaline ground water discharges in springs, atmospheric CO2 dissolves into the water and thick layers of calcite form. Iron, manganese, and other metals in the metallic portion of the slag have corroded to form more stable low-temperature oxides and sulfides and have not accumulated in large concentrations in the ground water. Calcite precipitated at the springs is rich in a number of heavy metals, suggesting that metals can move through the system as particulate matter. Air sparging appears to be an effective remediation strategy for reducing the toxicity of discharging alkaline water.

Notes: Artificial neural networks (ANNs) were developed to accurately predict highly time-variable specific conductance values in an unconfined coastal aquifer. Conductance values in the fresh water lens aquifer change in response to vertical displacements of the brackish zone and fresh water–salt water interface, which are caused by variable pumping and climate conditions. Unlike physical-based models, which require hydrologic parameter inputs, such as horizontal and vertical hydraulic conductivities, porosity, and fluid densities, ANNs can “learn” system behavior from easily measurable variables. In this study, the ANN input predictor variables were initial conductance, total precipitation, mean daily temperature, and total pumping extraction. The ANNs were used to predict salinity (specific conductance) at a single monitoring well located near a high-capacity municipal-supply well over time periods ranging from 30 d to several years. Model accuracy was compared against both measured/interpolated values and predictions were made with linear regression, and in general, excellent prediction accuracy was achieved. For example, although the average percent change of conductance over 90-d periods was 39%, the absolute mean prediction error achieved with the ANN was only 1.1%. The ANNs were also used to conduct a sensitivity analysis that quantified the importance of each of the four predictor variables on final conductance values, providing valuable insights into the dynamics of the system. The results demonstrate that the ANN technology can serve as a powerful and accurate prediction and management tool, minimizing degradation of ground water quality to the extent possible by identifying appropriate pumping policies under variable and/or changing climate conditions.

Notes: A new distance-drawdown method for aquifers with anisotropy on the horizontal plane is presented. The method uses scalar transformation to convert to an equivalent, isotropic medium, thus permitting application of the Cooper-Jacob Method. The method is applicable to cases where at least one ellipse of equal drawdown can be delineated but can also be applied where no ellipse can be discerned from the data. In the latter case, a least-squares regression approach can be employed to estimate the orientation and magnitude of the anisotropy. The regression R2 value provides a quantitative assessment of the degree to which the drawdown data are indicative of a systematic areal anisotropy in the aquifer or whether the data simply reflect natural aquifer heterogeneity. In addition to confined aquifers, this methodology, like the Cooper-Jacob Method, is also applicable to unconfined aquifers either before the onset of delayed drainage or following the completion of delayed drainage provided that the u value meets the recommended criterion.

Notes: A new multilayer approach is presented for the modeling of ground water flow to radial collector wells. The approach allows for the inclusion of all aspects of the unique boundary condition along the lateral arms of a collector well, including skin effect and internal friction losses due to flow in the arms. The hydraulic conductivity may differ between horizontal layers within the aquifer, and vertical anisotropy can be taken into account. The approach is based on the multilayer analytic element method, such that regional flow and local three-dimensional detail may be simulated simultaneously and accurately within one regional model. Horizontal flow inside a layer is computed analytically, while vertical flow is approximated with a standard finite-difference scheme. Results obtained with the proposed approach compare well to results obtained with three-dimensional analytic element solutions for flow in unconfined aquifers. The presented approach may be applied to predict the yield of a collector well in a regional setting and to compute the origin and residence time, and thus the quality, of water pumped by the collector well. As an example, the addition of three lateral arms to a collector well that already has three laterals is investigated. The new arms are added at an elevation of 2 m above the existing laterals. The yield increase of the collector well is computed as a function of the lengths of the three new arms.

Notes: Israel and the Palestinian Authority share the southern Mediterranean coastal aquifer. Long-term overexploitation in the Gaza Strip has resulted in a decreasing water table, accompanied by the degradation of its water quality. Due to high levels of salinity and nitrate and boron pollution, most of the ground water is inadequate for both domestic and agricultural consumption. The rapid rate of population growth in the Gaza Strip and dependence upon ground water as a single water source present a serious challenge for future political stability and economic development. Here, we integrate the results of geochemical studies and numerical modeling to postulate different management scenarios for joint management between Israel and the Palestinian Authority. The chemical and isotopic data show that most of the salinity phenomena in the Gaza Strip are derived from the natural flow of saline ground water from Israel toward the Gaza Strip. As a result, the southern coastal aquifer does not resemble a classic “upstream-downstream” dispute because Israel's pumping of the saline ground water reduces the salinization rates of ground water in the Gaza Strip. Simulation of different pumping scenarios using a monolayer, hydrodynamic, two-dimensional model (MARTHE) confirms the hypothesis that increasing pumping along the Gaza Strip border combined with a moderate reduction of pumping within the Gaza Strip would improve ground water quality within the Gaza Strip. We find that pumping the saline ground water for a source of reverse-osmosis desalination and then supplying the desalinated water to the Gaza Strip should be an essential component of a future joint management strategy between Israel and the Palestinian Authority.

Notes: Recent legislation required regional grassroots water resources planning across the entire state of Texas. The Texas Water Development Board (TWDB), the state's primary water resource planning agency, divided the state into 16 planning regions. Each planning group developed plans to manage both ground water and surface water sources and to meet future demands of various combinations of domestic, agricultural, municipal, and industrial water consumers. This presentation describes the challenges in developing a ground water model for the Llano Estacado Regional Water Planning Group (LERWPG), whose region includes 21 counties in the Southern High Plains of Texas. While surface water is supplied to several cities in this region, the vast majority of the regional water use comes from the High Plains aquifer system, often locally referred to as the Ogallala Aquifer. Over 95% of the ground water demand is for irrigated agriculture. The LERWPG had to predict the impact of future TWDB-projected water demands, as provided by the TWDB, on the aquifer for the period 2000 to 2050. If detrimental impacts were noted, alternative management strategies must be proposed. While much effort was spent on evaluating the current status of the ground water reserves, an appropriate numerical model of the aquifer system was necessary to demonstrate future impacts of the predicted withdrawals as well as the effects of the alternative strategies. The modeling effort was completed in the summer of 2000. This presentation concentrates on the political, scientific, and nontechnical issues in this planning process that complicated the modeling effort. Uncertainties in data, most significantly in distribution and intensity of recharge and withdrawals, significantly impacted the calibration and predictive modeling efforts. Four predictive scenarios, including baseline projections, recurrence of the drought of record, precipitation enhancement, and reduced irrigation demand, were simulated to identify counties at risk of low final ground water storage volume or low levels of satisfied demand by 2050.

Notes: Ground water is a vital, but underappreciated, natural resource in the Great Lakes basin. It meets many human needs and contributes significantly to the hydrology of the Great Lakes and the health of ecosystems. This paper provides an overview of ground water in the Great Lakes and the institutional and legal setting that governs the use, protection, diversion, and removal of water from the basin and proposes a citizen-centered vision for management of ground water in the 21st century.

Notes: Intermontane basins in the Trans-Pecos region of westernmost Texas and northern Chihuahua, Mexico, are target areas for disposal of interstate municipal sludge and have been identified as possible disposal sites for low-level radioactive waste. Understanding ground water movement within and between these basins is needed to assess potential contaminant fate and movement. Four associated basin aquifers are evaluated and classified; the Red Light Draw Aquifer, the Northwest Eagle Flat Aquifer, the Southeast Eagle Flat Aquifer, and the El Cuervo Aquifer. Encompassed on all but one side by mountains and local divides, the Red Light Draw Aquifer has the Rio Grande as an outlet for both surface drainage and ground water discharge. The river juxtaposed against its southern edge, the basin is classified as a topographically open, through-flowing basin. The Northwest Eagle Flat Aquifer is classified as a topographically closed and drained basin because surface drainage is to the interior of the basin and ground water discharge occurs by interbasin ground water flow. Mountains and ground water divides encompass this basin aquifer on all sides; yet, depth to ground water in the interior of the basin is commonly 〉500 feet. Negligible ground water discharge within the basin indicates that ground water discharges from the basin by vertical flow and underflow to a surrounding basin or basins. The most likely mode of discharge is by vertical, cross-formational flow to underlying Permian rocks that are more porous and permeable and subsequent flow along regional flowpaths beneath local ground water divides. The Southeast Eagle Flat Aquifer is classified as a topographically open and drained basin because surface drainage and ground water discharge are to the adjacent Wildhorse Flat area. Opposite the Eagle Flat and Red Light Draw aquifers is the El Cuervo Aquifer of northern Chihuahua, Mexico. The El Cuervo Aquifer has interior drainage to Laguna El Cuervo, which is a phreatic playa that also serves as a focal point of ground water discharge. Our evidence suggests that El Cuervo Aquifer may lose a smaller portion of its discharge by interbasin ground water flow to Indian Hot Springs, near the Rio Grande. Thus, El Cuervo Aquifer is a topographically closed basin that is either partially drained if a component of its ground water discharge reaches Indian Hot Springs or undrained if all its natural ground water discharge is to Laguna El Cuervo.

Notes: Transboundary aquifers are as important a component of global water resource systems as are transboundary rivers; yet, their recognition in international water policy and legislation is very limited. Existing international conventions and agreements barely address aquifers and their resources. To rectify this deficiency, the International Association of Hydrogeologists and UNESCO's International Hydrological Programme have established the Internationally Shared (transboundary) Aquifer Resource Management (ISARM) Programme. This multiagency cooperative program has launched a number of global and regional initiatives. These are designed to delineate and analyze transboundary aquifer systems and to encourage riparian states to work cooperatively toward mutually beneficial and sustainable aquifer development. The agencies participating in ISARM include international and regional organizations (e.g., Organization of American States, United Nations Environment Programme, United Nations Economic Commission for Europe, Food and Agriculture Organization, and South African Development Community). Using outputs of case studies, the ISARM Programme is building scientific, legal, environmental, socioeconomic, and institutional guidelines and recommendations to aid sharing nations in the management of their transboundary aquifers. Since its start in 2000, the program has completed inventories of transboundary aquifers in the Americas and Africa, and several ISARM case studies have commenced.

Notes: The combination of flowmeter and depth-dependent water-quality data was used to evaluate the quantity and source of high-chloride water yielded from different depths to eight production wells in the Pleasant Valley area of southern California. The wells were screened from 117 to 437 m below land surface, and in most cases, flow from the aquifer into the wells was not uniformly distributed throughout the well screen. Wells having as little as 6 m of screen in the overlying upper aquifer system yielded as much as 50% of their water from the upper system during drought periods, while the deeper parts of the well screens yielded 15% or less of the total yield of the wells. Mixing of water within wells during pumping degraded higher-quality water with poorer-quality water from deeper depths, and in some cases with poorer-quality water from the overlying upper aquifer system. Changes in the mixture of water within a well, resulting from changes in the distribution of flow into the well, changed the quality of water from the surface discharge of wells over time. The combination of flowmeter and depth-dependent water quality data yielded information about sources of high-chloride water to wells that was not available on the basis of samples collected from nearby observation wells. Changing well design to eliminate small quantities of poor-quality water from deeper parts of the well may improve the quality of water from some wells without greatly reducing well yield.

Notes: This paper describes reactive transport simulations conducted to assess the impact of mineral fouling on the hydraulic behavior of continuous-wall permeable reactive barriers (PRBs) employing granular zero-valent iron (ZVI) in carbonate-rich alluvial aquifers. The reactive transport model included a geochemical algorithm for simulating corrosion and mineral precipitation reactions that have been observed in ZVI PRBs. Results of simulations show that porosity and hydraulic conductivity of the ZVI decrease over time and that flows are redistributed throughout the PRB in response to fouling of the pore space. Under typical conditions, only subtle changes occur within the first 10 years (i.e., duration of the current field experience record with PRBs), and the most significant changes do not occur until the PRB has operated for at least 30 years. However, changes can occur sooner (or later) if the rate at which mineral-forming ions are delivered to the PRB is higher (or lower) than that expected under typical conditions (i.e., due to higher/lower flow rate or inflowing ground water that has higher/lower ionic strength). When the PRB is more permeable than the aquifer, the median Darcy flux in the PRB does not change appreciably over time because the aquifer controls the rate of flow through the PRB. However, seepage velocities in the PRB increase, and residence times decrease, due to porosity reductions caused by accumulation of minerals in the pore space. When fouling becomes extensive, bypassing and reductions in flow rate in the PRB occur.

Notes: Heat was used as a natural tracer to characterize shallow ground water flow beneath a complex wetland system. Hydrogeologic data were combined with measured vertical temperature profiles to constrain a series of two-dimensional, transient simulations of ground water flow and heat transport using the model code SUTRA (Voss 1990). The measured seasonal temperature signal reached depths of 2.7 m beneath the pond. Hydraulic conductivity was varied in each of the layers in the model in a systematic manual calibration of the two-dimensional model to obtain the best fit to the measured temperature and hydraulic head. Results of a series of representative best-fit simulations represent a range in hydraulic conductivity values that had the best agreement between simulated and observed temperatures and that resulted in simulated pond seepage values within 1 order of magnitude of pond seepage estimated from the water budget. Resulting estimates of ground water discharge to an adjacent agricultural drainage ditch were used to estimate potential dissolved organic carbon (DOC) loads resulting from the restored wetland. Estimated DOC loads ranged from 45 to 1340 g C/(m2 year), which is higher than estimated DOC loads from surface water. In spite of the complexity in characterizing ground water flow in peat soils, using heat as a tracer provided a constrained estimate of subsurface flow from the pond to the agricultural drainage ditch.

Notes: A total of 176 wells in sand-and-gravel glacial aquifers in central Illinois were sampled for arsenic (As) and other chemical parameters. The results were combined with archived and published data from several hundred well samples to determine potential sources of As and the potential geochemical controls on its solubility and mobility. There was considerable spatial variability in the As concentrations. High concentrations were confined to areas smaller than 1 km in diameter. Arsenic and well depth were uncorrelated. Arsenic solubility appeared to be controlled by oxidation-reduction (redox) conditions, especially the presence of organic matter. Geochemical conditions in the aquifers are typically reducing, but only in the most reducing water does As accumulate in solution. In wells in which total organic carbon (TOC) was below 2 mg/L and sulfate (SO42−) was present, As concentrations were low or below the detection limit (0.5 μg/L). Arsenic concentrations 〉10 μg/L were almost always found in wells where TOC was 〉2 mg/L and SO42− was absent or at low concentrations, indicating post–SO42−reducing conditions. Iron (Fe) is common in the aquifer sediments, and Fe oxide reduction appears to be occurring throughout the aquifers. Arsenic is likely released from the solid phase as Fe oxide is reduced.

Notes: A nitrate-reactive porous media layer comprising wood particles with very high hydraulic conductivity (K∼ 1 cm/s) was used to successfully treat nitrate in a shallow sand-and-gravel aquifer in southern Ontario. Nitrate concentrations of 1.3 to 14 mg/L as N in the aquifer were attenuated to 〈0.5 mg/L as N in the reactive layer. Borehole dilution testing indicated that ground water velocities in the reactive layer, although variable, averaged five times higher than in the surrounding aquifer, suggesting that the layer was capturing ground water flow from deeper in the aquifer. The use of high-K reactive media opens up the possibility of installing permeable reactive barriers as horizontal layers in the shallow water table zone that do not necessarily have to penetrate the full depth of a contaminant plume to be effective. Model simulations show that the depth of capture of a high-K layer increases as the layer width in the direction of flow increases. Shallower emplacement could decrease barrier costs at some sites.

Notes: The Blue Ridge Province contains ubiquitous northeast-southwest–trending thrust faults or smaller thrust “slivers” that greatly impact the nature and character of ground water flow in this region. Detailed investigations at a field site in Floyd County, Virginia, indicate that high-permeability zones occur in the brittle crystalline rocks above these thrust faults. Surface and borehole geophysics, aquifer tests, and chlorofluorocarbon and geochemical data reveal that the shallow saprolite aquifer is separated from the deeper fault-zone aquifer by a low–fracture permeability bedrock confining unit, the hydraulic conductivity of which has been estimated to be six orders of magnitude less than the conductivity of the fault zones at the test site. Within the Blue Ridge Province, these fault zones can occur at depths of 300 m or more, can contain a significant amount of storage, and yield significant quantities of water to wells. Furthermore, it is expected that these faults may compartmentalize the deep aquifer system. Recharge to and discharge from the deep aquifer occurs by slow leakage through the confining unit or through localized breach zones that occur where quartz accumulated in high concentrations during metamorphism and later became extensively fractured during episodes of deformation. The results of this investigation stress the importance of thrust faults in this region and suggest that hydrogeologic models for the Blue Ridge Province include these ancient structural features. Faults in crystalline-rock environments may not only influence the hydrology, they may dominate the flow characteristics of a region.

Notes: Uncertainty of hydrogeologic conditions makes it important to consider alternative plausible models in an effort to evaluate the character of a ground water system, maintain parsimony, and make predictions with reasonable definition of their uncertainty. When multiple models are considered, data collection and analysis focus on evaluation of which model(s) is(are) most supported by the data. Generally, more than one model provides a similar acceptable fit to the observations; thus, inference should be made from multiple models. Kullback-Leibler (K-L) information provides a rigorous foundation for model inference that is simple to compute, is easy to interpret, selects parsimonious models, and provides a more realistic measure of precision than evaluation of any one model or evaluation based on other commonly referenced model selection criteria. These alternative criteria strive to identify the true (or quasi-true) model, assume it is represented by one of the models in the set, and given their preference for parsimony regardless of the available number of observations the selected model may be underfit. This is in sharp contrast to the K-L information approach, where models are considered to be approximations to reality, and it is expected that more details of the system will be revealed when more data are available. We provide a simple, computer-generated example to illustrate the procedure for multimodel inference based on K-L information and present arguments, based on statistical underpinnings that have been overlooked with time, that its theoretical basis renders it preferable to other approaches.

Notes: This paper presents a critical review of model-input parameters for transport of on-site wastewater treatment system (OWS) pollutants. Approximately 25% of the U.S. population relies on soil-based OWS for effective treatment and protection of public health and environmental quality. Mathematical models are useful tools for understanding and predicting the transport and fate of wastewater pollutants and for addressing water-budget issues related to wastewater reclamation from site to watershed scales. However, input parameters for models that simulate fate and transport of OWS pollutants are not readily obtained. The purpose of this analysis is to illustrate an objective, statistically supported method for choosing model-input parameters related to nitrogen (N) and phosphorus (P). Data were gathered from existing studies reported in the literature. Cumulative frequency distributions (CFDs) are provided for OWS effluent concentrations of N and P, nitrification and denitrification rates, and linear sorption isotherm constants for P. When CFDs are not presented, ranges and median values are provided. Median values for model-input parameters are as follows: total N concentration (44 mg/L), nitrate-N (0.2 mg/L), ammonium (60 mg/L), phosphate-P (9 mg/L), organic N (14 mg/L), zero-order nitrification rate (264 mg/L/d), first-order nitrification (2.9/d), first-order dentrification (0.025/d), maximum soil capacity for P uptake (237 mg/kg), linear sorption isotherm constant for P (15.1 L/kg), and OWS effluent flow rates (260 L/person/d).

Notes: Boreholes drilled through contaminated zones in fractured rock create the potential for vertical movement of contaminated ground water between fractures. The usual assumption is that purging eliminates cross contamination; however, the results of a field study conducted in a trichloroethylene (TCE) plume in fractured sandstone with a mean matrix porosity of 13% demonstrates that matrix-diffusion effects can be strong and persistent. A deep borehole was drilled to 110 m below ground surface (mbgs) near a shallow bedrock well containing high TCE concentrations. The borehole was cored continuously to collect closely spaced samples of rock for analysis of TCE concentrations. Geophysical logging and flowmetering were conducted in the open borehole, and a removable multilevel monitoring system was installed to provide hydraulic-head and ground water samples from discrete fracture zones. The borehole was later reamed to complete a well screened from 89 to 100 mbgs; persistent TCE concentrations at this depth ranged from 2100 to 33,000 μg/L. Rock-core analyses, combined with the other types of borehole information, show that nearly all of this deep contamination was due to the lingering effects of the downward flow of dissolved TCE from shallower depths during the few days of open-hole conditions that existed prior to installation of the multilevel system. This study demonstrates that transfer of contaminant mass to the matrix by diffusion can cause severe cross contamination effects in sedimentary rocks, but these effects generally are not identified from information normally obtained in fractured-rock investigations, resulting in potential misinterpretation of site conditions.