Environmental Science & Technology

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Pueraria lobata Willd. (Ohwi) kudxa: Limitations to Sexual Reproduction
(1983) Abramovitz, Janet Naomi; Teramura, Alan H.; Botany; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
The success of kudzu, Pueraria lobata Willd. (Ohwi), as a weedy invader in the southeastern United States is a result of its rapid growth rate, high leaf area index and ability to reproduce vegetatively. Populations at three sites near College Park, Maryland varied in their growth and reproduction, leaf area index, specific leaf weight, vine elongation rates, raceme density and seed production and dispersal. Soil characteristics, air temperature, humidity and photosynthetically active radiation (PAR) were measured at each site. The site which had the greatest vegetative productivity received significantly higher levels of PAR. Virtually no flowers or seeds were produced at the other two sites. At the site which produced a large number of flowers, successful sexual reproduction was limited by insufficient pollinator service during some periods of the season and low germination and seedling survivorship. Measurements of specific leaf weight, leaf area index, biomass, raceme production and seed set suggest that kudzu is a sun adapted plant. Even though it is capable of establishing itself in habitats of low or moderate irradiance, a greater ability for sexual reproduction was apparent in sun populations versus no sexual reproduction was apparent in sun populations versus no sexual reproductive success in populations occurring in shaded habitats. While its primary mode of reproduction is vegetative, successful sexual reproduction may occur despite several limiting factors.
Preliminary Stock Assessment of The Chesapeake Bay Blue Crab Population
(1989) Knotts, Karen Sue; Rothschild, Brian J.; Environmental Science & Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
A preliminary stock assessment using data from a commercial fishery survey was completed. The maximum average attainable size (Linf) was found to be 174.25 mm (6.9 in) for males, and 171.7 mm (6.8 in) for females. The von Bertalanffy growth coefficient (K) was determined to be 0.83 for males and 0.57 for females. Yield-per-recruit analysis indicated that a significant amount of yield-per-recruit is lost if males are fished before reaching approximately 145 mm (5.7 inches). Results for females show that the size at first capture should be approximately 124 mm (5 inches), after which the yield-per-recruit gained by waiting is minimal. The nature of the recruitment-stock relationship could not be characterized in this study; however, results indicate that a relationship does exist. A comparison of early and late season catch curves indicated surplus production of biomass in the 1987 pot fishery. The potential use of change in sex ratios estimators for stock assessment is discussed.
Soils with Spodic Characteristics on the Eastern Shore of Maryland
(1990) Condron, Margaret Anne; Rabenhorst, Martin C.; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
A seasonally fluctuating water table may be an important factor in the formation of spodic horizons in sandy, quartzose sediments on the Lower Eastern Shore of Maryland. This study was conducted to examine spodic horizon formation and expression along two topohydrosequences. After a reconnaissance study, two research sites were chosen in the Pocomoke State Forest in Worcester County, Maryland. The soils were classified according to Soil Taxonomy as siliceous, mesic, Typic Quartzipsamments, Aquic Haplorthods, and Aerie and Typic Haplaquods. The spodic horizons were thickest (26-204cm) in the wettest positions. Total organic carbon, pyrophosphateextractable carbon, and extractable aluminum were greatest in the spodic horizons, and there was little extractable iron in the Haplaquods. There was less structural aluminum and potassium in the surface horizons than in the lower horizons. This suggests that feldspar weathering in the surface horizons provides a source of aluminum for the spodic horizon formation. Quantitative estimates of pedogenesis showed net gains of extractable aluminum, total (organic) carbon, and pyrophosphate carbon in the lower landscape positions. The seasonally fluctuating water table appears to influence the movement of soluble organic aluminum complexes through the soil downslope, as well as within the pedon from the surface to subjacent horizons.
Soils Developed in Freshwater Marl Sediments in The Hagerstown (Great) Limestone Valley
(1993) Shaw, Joey N.; Rabenhorst, Martin C.; Agronomy; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)
Certain calcareous soils occupying alluvial landscape positions in the Hagerstown (Great) limestone valley of western Maryland have developed from highly calcareous ( 60-100g/100g) marl sediments of Holocene age which range in depth from .5m to over 8m. These marlderived soils have a high pH ( 7. 5-8. 5) , low bulk density, and high porosity (0.5 to 0.6). The carbonate in the marl was developed from inorganic and biogenic processes. The marl was formed in now extinct ponds which had inundated alluvial landscape positions during parts of the Holocene period. Certain algae capable of accumulating carbonate internally and externally developed the majority of the marl. Pedogenic processes have transformed the marl sediments into highly calcareous Mollisols. The presence of buried surface horizons and coarse (> fine sand) carbonate forms render classification of these soils problematic. The coarse carbonate forms were mainly biogenic deposits, but these carbonates have been altered sufficiently by coating with pedogenic carbonate to identify calcic horizons. The drainage class is difficult to interpret as a result of the gleyed appearance of the marl sediments (chroma <3) and the high pH of these soils which inhibits Fe oxide reduction. Most of the marl-derived soils (70%) are better drained than the previous classification indicates. These soils have been mapped in the Great Valley in units named for the warners series (fine-silty, carbonatic, mesic Fluvaquentic Haplaquolls) and the Massenet ta series (fine-loamy, carbonatic, mesic, Fluvaquentic Hapludolls). However, proper classification may place these soils in the Typic Calciudolls subgroup. Some soils originally mapped in the very poorly drained Dunning units are very poorly drained marl-derived soils.
Emergy Basis of Forest Systems
(1999) Tilley, David
A major question in natural resource management is how to integrate economic-use activities with the supporting ecosystems to maximize performance of the ecological-economic system. In this dissertation, the natural wealth of forested systems of three different sizes was evaluated with emergy: two watersheds of the Southern Appalachians, Macon County (N.C.), and North Carolina. Emergy is the total amount of energy of one form that was required directly and indirectly to make another form of energy. Values are reported as emdollars (Em$) which represent the economic activity resulting from resource use. Benefits provided by forested watersheds were quantified based on emergy required to develop and maintain each service or product. Total wealth contributed by the multiple-use Wine Spring Creek (WSC) watershed was 4300 Em$/ha/y, and was divided among scientific research (3450 Em$/ha/y), water yield (2060 Em$/ha/y), recreation (1880 Em$/ha), and timber (1440 Em$/ha/y). In the 1990's, timber accounted for 3% of world emergy use, 1% in the United States, 9% in North Carolina, 14% in Macon County, and 8% in the WSC watershed. Forest ecosystems captured 53% of environmental emergy in North Carolina, 81% in Macon County, and 100% in the WSC watershed. The importance of forest ecosystems to the U.S. economy were evaluated based on emergy flows of the U.S. forest products industry and international trade of forest products in North America. In 1993, the U.S. had an annual trade surplus in forest products worth 63 billion Em$. Simple models were developed to explore the temporal and spatial dynamics of emergy and transformity in forested watersheds. Transformity is the ratio of emergy to energy; it measures position in the energy hierarchy of energy forms. Temporally, transformity and emergy lagged energy levels in reaching steady-state. Spatially, emergy from mountain uplands converged to the stream network, making water and its carved basin locations of high empower density. A model, MULTIBEN, evaluated forest empower of multiple benefits given various combinations of economic investment in recreation and timbering. Maximum empower was found at an intermediate level of economic investment, suggesting that an optimum intensity of forest development exists.
CHROMIUM OXIDATION AND REDUCTION BY HYDROGEN PEROXIDE IN DIVERSE SOILS AND SIMPLE AQUEOUS SYSTEMS
(1999) Rock, Melanie Louise; Helz, George R.; James, Bruce R.; Chemistry; Environmental Science & Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
Hydrogen peroxide is being tested for in situ remediation of buried contaminants - either as a direct chemical oxidant in Fenton-type reactions or as a source of oxidizing equivalents in bioremediation. How it affects a common co-contaminant, Cr, is explored here in four chemically diverse high-Cr soils. Soils contaminated with high levels of soluble Cr(VI) from ore processing and soils containing high levels of recently reduced Cr(III) from electroplating waste showed marked increases in chromate after single applications of J-25 mM peroxide. Cr(VI) in the leachates exceeded the drinking water standard (2μM) by 1-3 orders of magnitude. Soluble Cr(III), in the form of dissolved organic complexes, contributed to the likelihood of Cr(III) oxidation. Anaerobic soil conditions at a tannery site prevented oxidation of Cr(III). Naturally occurring Cr in serpentine soil also resisted oxidation. Ambient soluble Cr(VI) in a contaminated aquifer disappeared from peroxide leachates below pH 5, then reappeared as peroxide levels declined. In solutions prepared under environmentally relevant conditions, aged 280 μM Cr(III) treated with 100 μM H2O2 showed increases in Cr(VI) over weeks with maximum oxidation rates achieved in solutions prepared with 2:1 and 4:1 OH^-:Cr. Although Cr(III) speciation differs in fresh and aged aqueous systems, a similar mechanism involving the pre-equilibrium step: Cr(OH)/ + OH- .,. Cr(OH)/ may account for Cr(III) oxidation in both systems. Under alkaline conditions, H2O2 enhanced the oxidative dissolution of Crn(OH)3n^0. The formation of peroxochromium compounds in the presence of H2O2 and Cr(VI) may account for the disappearance and reappearance of Cr(VI) in H2O2 treated soils; as does the possible formation and subsequent reoxidation of Crm\(OH)3n-2^2+ oligomers. Mobilization of hazardous Cr(VI) must be considered in plans to use H2O2 for remediation of chemically complex wastes. Once Cr(III) is oxidized to Cr(VI) by H2O2 it may persist long after applied H2O2 treatments have disappeared. Further, hexavalent Cr will behave as a catalyst toward H20 2 in soils, enhancing its oxidative capacity while helping to dissipate high levels of applied H2O2.
Eutrophication, Hypoxia and Trophic Transfer Efficiency in Chesapeake Bay
(2002) Hagy, James Dixon III; Boynton, Walter R.; Environmental Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
Coastal eutrophication is a global problem that has contributed to loss of estuarine habitats and potentially decreased fisheries production. Hypoxia is often observed in eutrophic estuaries where it can be an important cause of habitat loss. This study utilized a suite of empirical analyses to examine key linkages relating coastal eutrophication to hypoxia, trophic structure, and trophic transfer efficiency in Chesapeake Bay (CB), USA. A salt- and water-balance model, or "box" model, was developed to quantify large-scale physical transport for CB, an input to many subsequent analyses. Historical ( 1950-1999) dissolved oxygen (DO) data for CB showed that moderate hypoxia (DO<2.0 mg1^-1) increased ~3-fold, modulated by spring river flow. Severe hypoxia (DO<0.7 mg1^1) occurred only in high flow years during 1950-1967, but was present annually since 1968. Analysis using tree-structured regression showed that hypoxia was the most important factor determining patterns of macrobenthic biomass in Chesapeake Bay. Carbon budgets showed that, where habitat quality was poor, macrobenthic biomass was much less than could be supported by the organic carbon supply. In these cases, even dramatic reductions in carbon supply would not be expected to limit benthic production and by extension, trophic transfers to upper trophic levels via the benthos. The effect of eutrophication and hypoxia on trophic structure and trophic transfer efficiency were examined by estimating trophic flow networks for three regions of CB during summer. In addition, a series of "rules" were described and used to infer the trophic flow network for a "restored" middle CB from historical data, comparative ecological relationships and mass balance constraints. Excessive carbon now through bacteria was the most pronounced symptom of eutrophication in the modern mid Bay. The microbial food web transferred organic matter to trophic levels comparable to large piscivorous predators, maintaining average trophic transfer efficiency, even as the fraction of primary production transferred to top predators decreased. In the restored Bay, increased macrobenthic production shifted metabolic activity away from the microbial food web, increasing the potential trophic transfer to fish by 7-fold, even as total primary production decreased to 63% of the current average.
A COMPARATIVE HYDROLOGIC ANALYSIS OF SURFACE MINED AND FORESTED WATERSHEDS IN WESTERN MARYLAND
(2002) Negley, Timothy Lee; Eshleman, Keith N.; Environmental Science & Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
This thesis presents the results of a hydrologic analysis conducted as part of a larger, multi-faceted, collaborative effort to study ecosystem function of a watershed subjected to surface mining and reclamation in the Appalachian Region of the United States. The primary goal of this study was to determine whether a small watershed subjected to surface mine reclamation practices (MAT 1) displayed a stormflow response to rain events that was different from those displayed by a young second-growth forested watershed (NEFl). A secondary goal was to investigate whether intensive surface mining in the Georges Creek basin has altered stormflow response at a larger river basin scale when compared to a similar, but predominantly forested basin (Savage River). At the small watersheds, MATl produced greater a) runoff coefficients (2.5x); b) total runoff (3x); and c) peak runoff rates (2x) compared to NEFl. Total rainfall explained 63% of the variation in total runoff at MAT I compared to only 21 % of the variation in total runoff at NEF I. Regardless of a recent 13% increase in surface mine reclamation in the Georges Creek basin, little difference in stormflow response was observed for 15 storms analyzed across the two larger basins. Georges Creek on average responded 3 hr more quickly than Savage River, However the hydrological response characteristics of the two basins were similar. In addition, hydrological response characteristics for Georges Creek and Savage River remained relatively stable over time. Further research is needed to address inabilities to scale responses observed at the small watersheds.
Relating Spore Population of Acid Producing Thermophilic Organisms and Artificially Inoculated Bacillus stearothermophilus to Processing Variables During Extrusion of a Standardized Feed Formulation
(2003-12-04) Okelo, Phares Odiewuor; Wheaton, Fredrick W; Carr, Lewis E; Joseph, Sam W; Douglass, Larry W; Biological Resources Engineering
Salmonella and other pathogenic organisms that infect poultry and other livestock can originate from feed or the environment. Technologies to control Salmonella infection in poultry are important measures taken to reduce turkey and poultry production losses. A study was designed to determine extrusion conditions that optimized microbial inactivation in feed using the Extru-tech E325 single-screw extruder. Bacillus stearothermophilus was selected as the indicator organism after no viable cells of Salmonella typhimurium were detected when 28.5 % moisture content mash feed (wet basis) was extruded at 83 C extruder barrel exit temperature with a 7 second feed retention time in the extruder barrel. Spores of B. stearothermophilus inoculated into a standardized feed formulation consisting of 60% corn meal, 30 % soybean meal,and 10% animal protein blend, by mass, respectively, was used to investigate the effect of 3 extrusion variables on microbial inactivation. The 3 variables were extruder barrel exit temperature (T), mash feed moisture content (Mc), and mean retention time of feed in the extruder barrel (Rt). A rotatable central composite statistical design was used with 3 factors and five levels. The quadratic response surface model fit to acid producing, thermophilic organisms and artificially inoculated Bacillus stearothermophilus spore inactivation data was used to predict extrusion conditions that maximized inactivation. The response surface indicated a stationary point within the design region that was a saddle at T = 81 C, Mc = 27.6 % wet basis (wb) and Rt = 8 s resulting in 0.170 log cycles of acid producing, thermophilic organisms and B. stearothermophilus spore inactivation. An estimated ridge of maximum inactivation showed a maximum of 1.03 log cycles at T = 110 C, Mc = 24.5 % wb and Rt = 11 s. Because the least severe extrusion conditions (T = 83 C, Mc = 28.5 % wb and Rt = 7 s) completely inactivated S. typhimurium in the standardized feed, it was speculated that all S. typhimurium cells would be inactivated at any set of extruder conditions within the central composite design region.
DETECTION OF PHYSICAL HAZARDS IN BONELESS POULTRY PRODUCT USING COMBINED X-RAY AND LASER RANGE IMAGING TECHNOLOGIES
(2003-12-05) Chen, Xin; Tao, Yang; Biological Resources Engineering
Detection of bone fragments and other physical contaminations in deboned poultry meat has become increasingly important to ensure food quality and safety. Traditional X-ray imaging detection technologies have significant difficulties detecting contaminations because of the meat tissue thickness variation. In order to address the thickness variation problem, in this study, a novel vision system with combined X-ray and laser 3D imaging technology has been developed for accurate physical contamination detection. The X-ray part of the combined system captures high resolution X-ray images in real-time, and the laser 3D part provides an accurate thickness profile for each piece of meat. In the combined system, the 3D thickness information is used to cancel the thickness variation in the X-ray image, thus the process of physical contamination detection is significantly simplified. The combined vision system is capable of detecting calcified bones (rib bones and pulley bones) at a 95% detection rate, and partially calcified bones (fan bones) at a 90% detection rate. In order to handle the inspection tasks in real-time, a multithread architecture is used in this vision system. Various threads work simultaneously in the system, synchronized with each other, taking full advantage of system resources. It is shown that real-time capability is achieved due to the multithread framework. The result of this study has the potential to promote food safety and quality by providing advanced and automated detection techniques to the poultry and food industries.
LASER RANGE IMAGING FOR ON-LINE MAPPING OF 3D IMAGES TO PSEUDO-X-RAY IMAGES FOR POULTRY BONE FRAGMENT DETECTION
(2003-12-16) Jing, Hansong; Tao, Yang; Biological Resources Engineering
A laser ranging image system was developed for on-line high-resolution 3D shape recovery of poultry fillets. The range imaging system in conjunction with X-ray imaging was used to provide synergistic imaging detection of bone fragments in poultry fillets. In this research, two 5 mW diode lasers coupled with two CCD cameras were used to produce 3D information based on structured lights and triangulation. A laser scattering phenomenon on meat tissues was studied when calculating the object thickness. To obtain the accurate 3D information, the cameras were calibrated to correct for camera distortions. For pixel registrations of the X-ray and laser 3D images, the range imaging system was calibrated, and noises and signal variations in the X-ray and laser 3D images were analyzed. Furthermore, the relationship between the X-ray absorption and 3D thickness of fillets was obtained, and a mapping function based on this relationship was applied to convert the fillet 3D images into the pseudo-X-ray images. For the on-line system implementation, the imaging hardware and software engineering issues, including the data flow optimization and the operating system task scheduling, were also studied. Based on the experimental on-line test, the range imaging system developed was able to scan poultry fillets at a speed of 0.2 m/sec at a resolution of 0.8(X) x 0.7(Y) x 0.7(Z) mm3. The results of this study have shown great potential for non-invasive detection of hazardous materials in boneless poultry meat with uneven thickness.
AN INFRARED AND LASER RANGE IMAGING SYSTEM FOR NON-INVASIVE ESTIMATION OF INTERNAL COOKING TEMPERATURE IN POULTRY FILLETS
(2003-12-16) Ma, Ling; Tao, Yang; Lo , Y. Martin; Johnson, Arthur T; Wheaton, Fredrick W; Biological Resources Engineering
Foodborne diseases caused by undercooked poultry products are noteworthy problems that have motivated research into the assessment of the endpoint temperature in meat. In this research, a novel infrared and laser range imaging system was proposed to estimate the internal cooking temperature of chicken breasts. It consisted of three subsystems: an IR imaging system, a laser range system, and an artificial neural network modeling system. Our experiments showed that geometric variables played an important role in the endpoint temperature estimation. The accuracy achieved by our system was 1.54° C for mean absolute error, 2% for mean absolute percent error, and 3.08(° C)2 for mean square error. The combined IR and laser range imaging system showed the potential for real-time, non-contact and non-invasive estimation of the internal cooking temperature in meat for enhanced food quality and safety.
Evaluation of Acetate Thresholds Under Various Terminal Electron-Accepting Conditions: Application to Bioremediation Monitoring
(2004-01-27) Su, Xiaomin; Becker, Jennifer G; Montas, Hubert J; Seagren, Eric A; Biological Resources Engineering
A major challenge associated with intrinsic bioremediation is demonstrating its success. The consumption of electron acceptors during bioremediation of hydrocarbons and other contaminants can result in shifts in the predominant terminal electron-accepting processes (TEAPs), which may be useful for monitoring. Because traditional assessment tools have disadvantages, an accurate indicator of TEAPs is still needed. Acetate thresholds were evaluated to test the hypothesis that characteristic ranges of acetate thresholds may exist for different TEAPs and be useful as a bioremediation monitoring tool. Acetate thresholds established by pure microbial batch cultures using different TEAPs were measured experimentally. Furthermore, the factors controlling acetate thresholds were investigated using a microbial respiration model. Acetate thresholds increased in the order: Fe(III)
Quantification of the Effectiveness of Agricultural Riparian Buffers to Protect Stream Health in Maryland's Coastal Plain and Piedmont Regions
(2004-03-09) Barker, Linda Suzann; Felton, Gary K; Biological Resources Engineering
This research quantified the effectiveness of agricultural riparian buffers to protect stream health in Maryland's Coastal Plain and Piedmont physiographic regions. Easily-obtainable data were used to develop scientific guidance for buffer management strategies. Three data sets were used: the 1998 University of Maryland Agricultural Buffer Survey, the 1996 Smithsonian Environmental Research Center Water Quality Survey, and the 1995-1997 Maryland Biological Stream Survey. Collectively, these data were used to represent baseflow water quality and landscape conditions in agricultural catchments. A set of landscape characteristics describing the agricultural riparian landscape was developed, from which a classification system for agricultural riparian landscapes was developed. The Agricultural Riparian Classification System can identify a subset of sites for targeted research. Additionally, the distribution of agricultural riparian buffers was characterized. Although over 70% of sites were buffered, because the statewide average buffer width was approximately 49 meters, almost 50% of buffers could not be detected by remotely sensed data with a resolution of 30 meters. Models were developed to predict measures of stream health at a site. Buffers acted differently on instream nitrate concentration, fish IBI (FIBI), benthic IBI (BIBI), and instream physical habitat (PHI). All models indicated that nitrate source terms overshadowed any on-site buffer effects and that Confined Animal Feeding Operations and pastures acted as point sources, overwhelming non-point-source effects. Therefore, livestock best managements practices are critical for the reduction of nitrate to streams. Fish IBI, benthic IBI and physical habitat index (PHI) in the Piedmont region were unaffected by buffer presence, but benthic IBI and PHI in the Coastal Plain were affected by buffer presence, type and width. Regression tree modeling was able to delineate a range of minimum effective buffer width between 22-38 meters. All measures of stream health in Piedmont systems were controlled by hydrology and geomorphology. Therefore, insofar as buffers can mediate hydrologic effects on flow conditions in a stream, they may indirectly affect FIBI, and BIBI and PHI in Piedmont systems. Use of fish IBI to measure success of buffer installation or restoration would give false results.
ELECTROPHORETIC REMOVAL OF FINE PARTICULATES FROM AQUCULTURE EFFLUENT
(2004-04-26) Hanna, Kalim; Wheaton, Fredrick; Biological Resources Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
As larger waste particles breakdown into smaller pieces under the mechanical stress of a recirculating system, it becomes increasingly more difficult to remove these particles through standard methods. This current work explores the possibility of using an impressed electric field as a means of water clarification. In this study aquaculture effluent is passed through an imposed electric field, where the fluid column is divided into two fluid streams: one closest to the positive electrode, and the other closest to the negative electrode. The water quality of each fluid stream is analyzed to determine if any difference results due to its exposure to the electric field. While this study did show that there was a statistically significant difference in certain water quality parameters between the two fluid streams, it was clear that the process was not efficient enough to be considered a viable and effective means of water clarification.
NON-INVASIVE IMAGING TECHNIQUES AS A QUANTITATIVE ANALYSIS OF SKIN DAMAGE DUE TO IONIZING RADIATION
(2004-05-06) Vogel, Abby Jeanne; Tao, Yang; Biological Resources Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
This study tested the ability of two non-invasive techniques, thermography and near-infrared multi-spectral imaging, to quantitatively assess the response of mouse skin to a single dose of X-ray irradiation. Thermal images from an 8-12 micron thermal camera were recorded after a cold stimulation to see the thermal recovery of the skin. The irradiated areas showed a significantly faster thermal recovery than the non-irradiated areas two weeks after radiation (p < 0.05). The NIR multi-spectral imager obtained images at six specially selected wavelengths between 700 and 1000 nm. Two-layer model-based diffuse reflectance spectroscopy monitored changes in blood oxygen saturation and blood volume. Blood oxygen fractions were significantly lower after radiation (p < 0.05). Blood volume changed in six of seven irradiated mice one week after radiation. The non-invasive imaging techniques were successful in quantitatively analyzing the response of the skin to a single dose of irradiation.
Investigation into the system dynamics of a wetland soil technoecoysystem using redox potential as a metabolic indicator and feedback control parameter
(2004-05-12) Blersch, David Michael; Kangas, Patrick C.; Biological Resources Engineering
The engineering of technoecosystems (technological-ecological hybrids) was investigated, focusing specifically on novel behavior exhibited by an ecosystem when given control over its own energy sources via artificial feedback control circuits. A technoecosystem was constructed based upon wetland soil microcosms using redox potential as an indicator of system metabolism and as the controlled parameter. Two types of experiments were performed to elucidate system dynamics. Results of the carbon addition experiments exhibited an increase in the rate of decline of redox potential over time as a result of the feedback control system, indicating increased metabolism in the microcosms. Results of the carbon/nitrate selection experiments showed oscillatory redox potential over time, trending towards regulation of redox potential within a set range. Simple computational models of ecological limiting factors are developed to explain the results. A classification system for technoecosystems is proposed, and implications into technoecosystem intelligence and energetic autonomy are discussed.
MODEL OF EXERCISE PERFORMANCE WHILE WEARING A RESPIRATORY PROTECTIVE MASK
(2004-06-29) Chiou, Yinghsiang; Johnson, Arthur T; Biological Resources Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
This model emphasized respiratory responses and incorporated mathematical descriptions of experimental results obtained from exercising humans. Prediction equations for tidal volume, anaerobic threshold, minute volume, respiratory work, and performance time were included, as well as dynamic changes in each. This model can help to design future respirators, aid workers wearing respirators, and regulate occupational health and safety. In general, the current model can predict performance time when subjects exercise both with and without masks. The current model was fitted for 30% and 80% VO2max of experimental data from the Human Performance Laboratory (University of Maryland, College Park). The results showed predicted values were reasonable and closer to the experimental data. Results of physiological values and performance times showed that the model structure was valid and that the model was capable of making rational predictions of the average effects of respirator wear on the pulmonary system during physical activity.
Modeling and monitoring pathogen transport through vegetated filter strips
(2004-08-05) Roodsari, Gholamreza Moosapour; Shirmohammadi, Adel; Biological Resources Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Contamination of natural waters by microorganisms directly affects public health. Field application of manure can potentially result in surface and groundwater contamination. The objective of this study was to observe and quantify the effects of vegetated filter strips (VFS) on surface and subsurface transport of fecal oviform (FC) surrogates for bacterial pathogens released from a surface - applied bovine/swine manure. The study included a field-based lysimeter equipped with multi-sensor moisture probes to monitor real-time water content through the soil profile, and with other proper instrumentation to monitor and quantify the spatial and temporal release rates of pathogenic bacteria. Another component of this study involved development and testing of a computer model to predict the surface and subsurface transport of FC. Results showed that bare plots offered no resistance to surface flow, thus FC were detected in runoff at 600 cm from the ridge of the lysimeter within 10 minutes of the rainfall initiation. Results from vegetated plots showed that vegetation substantially attenuated surface flow of water as compared to bare plots. Unlike the bare soil, the results showed that the vegetated soil surface created a much less uniform transport pattern for FC. Vegetation changed transport patterns and levels of FC concentrations much more significantly than soil texture did. Results showed that E.coli and Salmonella cholerasuis behaved similarly and resulted in similar transport patterns in both bare plots. Results also showed that both organisms demonstrated a two-stage exponential release rate with a fast release rate in the first 10 minutes of the rainfall simulation. A one-dimensional convective-dispersive equation using the continuity equation and the Manning's equation were used in MODCHOI model (a modified version of KORMIL2) to predict the surface transport of FC. To simulate the vertical movement of FC, a one-dimensional kinematic wave model was developed and used. Green and Ampt, Philip, and Schmid infiltration models were also applied to the vertical water flow movement. The models simulated the spatial and the temporal distribution of FC in runoff assuming an exponential release of FC from the manure. Simulation results satisfactorily modeled both flow and FC.
DESIGN FOR A STAND-ALONE, UNIVERSAL SERIAL BUS (USB) -ENABLED AIRFLOW PERTURBATION DEVICE
(2004-08-12) Silverman, Nischom K; Johnson, Arthur T; Biological Resources Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The stand-alone, USB-enabled Airflow Perturbation Device (APD) provides an average respiratory resistance (RR) measurement without connection to a computer and offers expanded functionality when connected to a computer. In both home and medical clinic settings, RR can provide a measure of impairment in obstructive respiratory disorders and the effectiveness of respiratory therapies. The APD measures RR during passive breathing by sensing the ratio of pressure increase to flow reduction during brief, partial airflow interruptions. Prior work has shown the APD to produce repeatable, sensitive RR measurements in humans and animals. The device of prior investigations incorporated a computer and data acquisition card. The research presented here demonstrates that the APD can provide accurate measurements in a stand-alone format and provide expanded function with a USB host computer.