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• 1. [Article] Organic Particulate Matter Formation at Varying Relative Humidity Using Surrogate Secondary and Primary Organic Compounds with Activity Corrections in the Condensed Phase Obtained Using a Method Based on the Wilson Equation

  Secondary organic aerosol (SOA) formation in the atmosphere is currently often modeled using a multiple lumped "two-product" (N · 2p) approach. The N · 2p approach neglects: 1) variation of activity coefficient ...

  Citation × Citation Citation Abstract Copy Title: Organic Particulate Matter Formation at Varying Relative Humidity Using Surrogate Secondary and Primary Organic Compounds with Activity Corrections in the Condensed Phase Obtained Using a Method Based on the Wilson Equation Author: Pankow, James F., Chang, E. I. Year: 2010 Secondary organic aerosol (SOA) formation in the atmosphere is currently often modeled using a multiple lumped "two-product" (N · 2p) approach. The N · 2p approach neglects: 1) variation of activity coefficient (i) values and mean molecular weight MW in the particulate matter (PM) phase; 2) water uptake into the PM; and 3) the possibility of phase separation in the PM. This study considers these effects by adopting an (N ·2p)pMW, approach (is a phase index). Specific chemical structures are assigned to 25 lumped SOA compounds and to 15 representative primary organic aerosol (POA) compounds to allow calculation of i and MW values. The SOA structure assignments are based on chamber-derived 2p gas/particle partition coefficient values coupled with known effects of structure on vapor pressure pL,io (atm). To facilitate adoption of the (N · 2p)pMW, approach in large-scale models, this study also develops CP-Wilson.1 (Chang-Pankow-Wilson.1), a group-contribution ζi-prediction method that is more computationally economical than the UNIFAC model of Fredenslund et al. (1975). Group parameter values required by CP-Wilson.1 are obtained by fitting i values to predictions from UNIFAC. The (N · 2p)pMW,approach is applied (using CP-Wilson.1) to several real α-pinene/O3 chamber cases for high reacted hydrocarbon levels (HC400 to 1000 g m-3) when relative humidity (RH)50%. Good agreement between the chamber and predicted results is obtained using both the (N ·2p)pMW, and N ·2p approaches, indicating relatively small water effects under these conditions. However, for a hypothetical α-pinene/O3 case at HC=30 g m-3 and RH=50%, the (N·2p)pMW, approach predicts that water uptake will lead to an organic PM level that is more double that predicted by the N · 2p approach. Adoption of the (N · 2p)pMW, approach using reasonable lumped structures for SOA and POA compounds is recommended for ambient PM modeling. Title: Organic Particulate Matter Formation at Varying Relative Humidity Using Surrogate Secondary and Primary Organic Compounds with Activity Corrections in the Condensed Phase Obtained Using a Method Based on the Wilson Equation Author: Pankow, James F., Chang, E. I. Year: 2010 Secondary organic aerosol (SOA) formation in the atmosphere is currently often modeled using a multiple lumped "two-product" (N · 2p) approach. The N · 2p approach neglects: 1) variation of activity coefficient (i) values and mean molecular weight MW in the particulate matter (PM) phase; 2) water uptake into the PM; and 3) the possibility of phase separation in the PM. This study considers these effects by adopting an (N ·2p)pMW, approach (is a phase index). Specific chemical structures are assigned to 25 lumped SOA compounds and to 15 representative primary organic aerosol (POA) compounds to allow calculation of i and MW values. The SOA structure assignments are based on chamber-derived 2p gas/particle partition coefficient values coupled with known effects of structure on vapor pressure pL,io (atm). To facilitate adoption of the (N · 2p)pMW, approach in large-scale models, this study also develops CP-Wilson.1 (Chang-Pankow-Wilson.1), a group-contribution ζi-prediction method that is more computationally economical than the UNIFAC model of Fredenslund et al. (1975). Group parameter values required by CP-Wilson.1 are obtained by fitting i values to predictions from UNIFAC. The (N · 2p)pMW,approach is applied (using CP-Wilson.1) to several real α-pinene/O3 chamber cases for high reacted hydrocarbon levels (HC400 to 1000 g m-3) when relative humidity (RH)50%. Good agreement between the chamber and predicted results is obtained using both the (N ·2p)pMW, and N ·2p approaches, indicating relatively small water effects under these conditions. However, for a hypothetical α-pinene/O3 case at HC=30 g m-3 and RH=50%, the (N·2p)pMW, approach predicts that water uptake will lead to an organic PM level that is more double that predicted by the N · 2p approach. Adoption of the (N · 2p)pMW, approach using reasonable lumped structures for SOA and POA compounds is recommended for ambient PM modeling. Close

• 2. [Article] Exploring High-Resolution Data Obtained from ASC/3 Controller of Intersection SE Division St & SE 122nd Ave, Portland, Oregon.

  High-resolution data obtained from ASC/3 controllers can be used to create a variety of performance measures, helping engineers and professionals in monitoring intersection performance, identifying issues, ...

  Citation × Citation Citation Abstract Copy Title: Exploring High-Resolution Data Obtained from ASC/3 Controller of Intersection SE Division St & SE 122nd Ave, Portland, Oregon. Author: Al-Abbas, Naowar Year: 2018 High-resolution data obtained from ASC/3 controllers can be used to create a variety of performance measures, helping engineers and professionals in monitoring intersection performance, identifying issues, and making proper improvements. These measures concern the intersection quality of the progression, capacity, and non-vehicular operations (e.g. pedestrian crossings). In this report, we explored high-resolution data obtained from the intersection of SE Division Street and 122nd Avenue. This intersection had some safety concerns as it is considered one of most dangerous intersections in Portland, Oregon. Thus, the first variable we examined from the data was pedestrian wait time when a cross request is made until pass indication is shown. It was found around 60% of pedestrians who crossed in an east-west direction experienced a delay of 30 seconds or more. Although there was more pedestrian demand from the south to west direction, 70% of these pedestrians received a 30 second delay or longer. Delay values determined from controller data in this report only refer to pedestrians who made a request/call to cross at a particular direction in each cycle. Additionally, an alternate means of calculating actual pedestrian delay was also addressed. The other part of the analysis regarded vehicle operations and signal indications. Green time, cycle length, green-to-cycle ratio, and vehicle count per each cycle were all explored. Furthermore, the quality of the progression of coordinated phases of the through vehicular movement on SE division was quantitatively examined using the proportion of vehicles that had arrived during green indication and Arrival Type (AT), and visually, using the Purdue Coordination Diagram (PCD). The results showed that quality of progression was in good standard. Finally, errors found in the data and the accuracy of the results were also addressed. Title: Exploring High-Resolution Data Obtained from ASC/3 Controller of Intersection SE Division St & SE 122nd Ave, Portland, Oregon. Author: Al-Abbas, Naowar Year: 2018 High-resolution data obtained from ASC/3 controllers can be used to create a variety of performance measures, helping engineers and professionals in monitoring intersection performance, identifying issues, and making proper improvements. These measures concern the intersection quality of the progression, capacity, and non-vehicular operations (e.g. pedestrian crossings). In this report, we explored high-resolution data obtained from the intersection of SE Division Street and 122nd Avenue. This intersection had some safety concerns as it is considered one of most dangerous intersections in Portland, Oregon. Thus, the first variable we examined from the data was pedestrian wait time when a cross request is made until pass indication is shown. It was found around 60% of pedestrians who crossed in an east-west direction experienced a delay of 30 seconds or more. Although there was more pedestrian demand from the south to west direction, 70% of these pedestrians received a 30 second delay or longer. Delay values determined from controller data in this report only refer to pedestrians who made a request/call to cross at a particular direction in each cycle. Additionally, an alternate means of calculating actual pedestrian delay was also addressed. The other part of the analysis regarded vehicle operations and signal indications. Green time, cycle length, green-to-cycle ratio, and vehicle count per each cycle were all explored. Furthermore, the quality of the progression of coordinated phases of the through vehicular movement on SE division was quantitatively examined using the proportion of vehicles that had arrived during green indication and Arrival Type (AT), and visually, using the Purdue Coordination Diagram (PCD). The results showed that quality of progression was in good standard. Finally, errors found in the data and the accuracy of the results were also addressed. Close

• 3. [Article] Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network

  The highway transportation network of the United States relies on the health and integrity of major infrastructure elements such as bridges. Frequently traveled parts of Oregon are within the seismically ...

  Citation × Citation Citation Abstract Copy Title: Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network Author: Dusicka, Peter, Roberts, Jeffery Year: 2011 The highway transportation network of the United States relies on the health and integrity of major infrastructure elements such as bridges. Frequently traveled parts of Oregon are within the seismically active Pacific Northwest and many of the bridges were designed and built to lateral demands that were assumed to be less than the current expectation, a deficiency caused by our growing awareness of seismic hazard and our enhanced understanding of the non-linear response of bridges. This vulnerability to damage from earthquakes can result in not only immediate damage, but also in potentially lingering economic impact caused by the disruption to traffic and freight mobility. Using analytical methods, fragility curves were constructed assuming lognormal capacity and demand distributions. Probability of failure was determined for the four damage state conditions of slight, moderate, extensive, and complete levels of damage. These statistical values were compared to the median and dispersion values proposed by other researchers, in addition to those calculated using guidelines from the HAZUS Technical Manual. Older multiple-span Oregon bridges were found to be significantly more fragile than the HAZUS models. As a result of this modeling and analysis effort, the relative fragility of the modeled typical 3-span and 5-span bridges was determined and quantified. Possible causes of the relatively high fragilities were also considered. Title: Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network Author: Dusicka, Peter, Roberts, Jeffery Year: 2011 The highway transportation network of the United States relies on the health and integrity of major infrastructure elements such as bridges. Frequently traveled parts of Oregon are within the seismically active Pacific Northwest and many of the bridges were designed and built to lateral demands that were assumed to be less than the current expectation, a deficiency caused by our growing awareness of seismic hazard and our enhanced understanding of the non-linear response of bridges. This vulnerability to damage from earthquakes can result in not only immediate damage, but also in potentially lingering economic impact caused by the disruption to traffic and freight mobility. Using analytical methods, fragility curves were constructed assuming lognormal capacity and demand distributions. Probability of failure was determined for the four damage state conditions of slight, moderate, extensive, and complete levels of damage. These statistical values were compared to the median and dispersion values proposed by other researchers, in addition to those calculated using guidelines from the HAZUS Technical Manual. Older multiple-span Oregon bridges were found to be significantly more fragile than the HAZUS models. As a result of this modeling and analysis effort, the relative fragility of the modeled typical 3-span and 5-span bridges was determined and quantified. Possible causes of the relatively high fragilities were also considered. Close

• 4. [Article] Economic and Technological Analysis of the Key Factors Affecting the Competitiveness of Electric Commercial Vehicles

  Electric commercial vehicles’ (ECVs) energy costs are almost four times less expensive than conventional diesel trucks, on a per-mile basis, at current USA market values. However, ECVs are approximately ...

  Citation × Citation Citation Abstract Copy Title: Economic and Technological Analysis of the Key Factors Affecting the Competitiveness of Electric Commercial Vehicles Author: Feng, Wei, Figliozzi, Miguel A. Year: 2013 Electric commercial vehicles’ (ECVs) energy costs are almost four times less expensive than conventional diesel trucks, on a per-mile basis, at current USA market values. However, ECVs are approximately three times more expensive in terms of vehicle purchase costs. In addition, electric vehicles are simpler and cheaper to maintain there are more uncertainties associated to the life and long-term costs of the ECV batteries. Furthermore, there are limitations in terms of miles driven per day without recharging. These economic and technological tradeoffs motivate this research. Utilizing a fleet replacement optimization framework, a wide range of scenarios, and current USA market data this research finds the key economic and technological breakeven values where ECVs become competitive against conventional diesel counterparts. The results clearly indicate that only in scenarios with high utilization (over 16,000 miles per year per truck) the electric vehicles are competitive, this is especially valid if a battery replacement is not required before the electric commercial vehicle is replaced. The breakeven analysis results show that a 9–27% ECV price reduction can greatly increase their competitiveness when vehicles are driven over 12,000 miles per year. Title: Economic and Technological Analysis of the Key Factors Affecting the Competitiveness of Electric Commercial Vehicles Author: Feng, Wei, Figliozzi, Miguel A. Year: 2013 Electric commercial vehicles’ (ECVs) energy costs are almost four times less expensive than conventional diesel trucks, on a per-mile basis, at current USA market values. However, ECVs are approximately three times more expensive in terms of vehicle purchase costs. In addition, electric vehicles are simpler and cheaper to maintain there are more uncertainties associated to the life and long-term costs of the ECV batteries. Furthermore, there are limitations in terms of miles driven per day without recharging. These economic and technological tradeoffs motivate this research. Utilizing a fleet replacement optimization framework, a wide range of scenarios, and current USA market data this research finds the key economic and technological breakeven values where ECVs become competitive against conventional diesel counterparts. The results clearly indicate that only in scenarios with high utilization (over 16,000 miles per year per truck) the electric vehicles are competitive, this is especially valid if a battery replacement is not required before the electric commercial vehicle is replaced. The breakeven analysis results show that a 9–27% ECV price reduction can greatly increase their competitiveness when vehicles are driven over 12,000 miles per year. Close

• 5. [Article] A finite difference soil-structure interaction study of a section of the Bonneville Navigation Lock buttress diaphragm wall utilizing pressuremeter test results

  The P-y curve, used in current practice as an efficient Iine-load vs. soi displacement model for input into the finite difference method of laterally loaded pile analysis, is extended in this study for ...

  Citation × Citation Citation Abstract Copy Title: A finite difference soil-structure interaction study of a section of the Bonneville Navigation Lock buttress diaphragm wall utilizing pressuremeter test results Author: McCormack, Thomas C. Year: 1987 The P-y curve, used in current practice as an efficient Iine-load vs. soi displacement model for input into the finite difference method of laterally loaded pile analysis, is extended in this study for use with cohesionless soils in diaphragm wall analysis on the Personal Computer with the BMCOL7 program. An analogous W-y curve is proposed, an elastic-plastic model with line-load limits developed from classical earth-pressure theories. A new formula for predicting a horizontal walI modulus for cohesionless soiIs from the pressuremeter modulus is developed for use in predicting the displacements on the W-y curves. The resulting modulus values are shown to yield reasonable displacements values. A new procedure for modeling preloaded tie-back anchors and staged excavation for diaphragm walIs was developed, utiIizing multiple computer runs, updated the W-y curves, and superposition of deflections. These new developments were applied to a parametric study of a deflection-critical section of the new Bonnevilie Nav-Lock Buttress Diaphragm Wall, for which extensive high-quality pressuremeter test results were available. Deflection curves of the wall are presented, showing the effect of variations in anchor preload, walI cracking, anchor slip, at-rest pressure, and soiI modulus. The results indicate that preloading will reduce wall deflections by at least 4-fold, but that wall cracking can potentially double deflections. Safety factors against passive soil failure were determined to be about 5 at anchor preload, and more than 40 after fulI excavation. Title: A finite difference soil-structure interaction study of a section of the Bonneville Navigation Lock buttress diaphragm wall utilizing pressuremeter test results Author: McCormack, Thomas C. Year: 1987 The P-y curve, used in current practice as an efficient Iine-load vs. soi displacement model for input into the finite difference method of laterally loaded pile analysis, is extended in this study for use with cohesionless soils in diaphragm wall analysis on the Personal Computer with the BMCOL7 program. An analogous W-y curve is proposed, an elastic-plastic model with line-load limits developed from classical earth-pressure theories. A new formula for predicting a horizontal walI modulus for cohesionless soiIs from the pressuremeter modulus is developed for use in predicting the displacements on the W-y curves. The resulting modulus values are shown to yield reasonable displacements values. A new procedure for modeling preloaded tie-back anchors and staged excavation for diaphragm walIs was developed, utiIizing multiple computer runs, updated the W-y curves, and superposition of deflections. These new developments were applied to a parametric study of a deflection-critical section of the new Bonnevilie Nav-Lock Buttress Diaphragm Wall, for which extensive high-quality pressuremeter test results were available. Deflection curves of the wall are presented, showing the effect of variations in anchor preload, walI cracking, anchor slip, at-rest pressure, and soiI modulus. The results indicate that preloading will reduce wall deflections by at least 4-fold, but that wall cracking can potentially double deflections. Safety factors against passive soil failure were determined to be about 5 at anchor preload, and more than 40 after fulI excavation. Close

• 6. [Article] Understanding the Safety Effects of Roadway Illumination Reductions

  In 2001, Oregon’s governor responded to a perceived future energy shortage in the Pacific Northwest by directing all state agencies to reduce power consumption by 10 percent. After review of power saving ...

  Citation × Citation Citation Abstract Copy Title: Understanding the Safety Effects of Roadway Illumination Reductions Author: Monsere, Christopher M., Yin, Thareth, Wolfe, Michael Year: 2007 In 2001, Oregon’s governor responded to a perceived future energy shortage in the Pacific Northwest by directing all state agencies to reduce power consumption by 10 percent. After review of power saving opportunities, the Oregon Department of Transportation (ODOT) elected to include selective illumination reductions on Oregon interstate highways as part of their energy saving strategy. The illumination reductions occurred at interchanges and along lineal highway sections between October 2001 and April 2002. A total of 47 interchanges and 6.03 miles of interstate highways were modified. Changes in illumination were broadly classified as either full (including high-mast) to partial designs, partial plus to partial designs, or lineal reductions. In this study, no before or after field measurements were taken of actual luminance values, lighting coverage, or other design specific values. This research evaluated the changes in safety performance using crash, geometry, weather and volume data from years 1996 to 2005 using observational before-after evaluations using the : 1) the simple before-after and 2) empirical-bayes approach. The empirical-bayes approach found a 3.47 percent increase (4.65 standard deviation) in total night crashes where full interchange lighting was reduced to partial lighting. Fatal and injury night crashes, however, were found to decrease by 11.38%. For interchanges where illumination was reduced from partial plus to partial, a 35.24 percent decrease in total night crashes was found. A 29 percent increase in total night crashes (18.21 standard deviation) on sections where the lineal lighting was modified was found. Weighing all evidence, the research concludes that a decrease in safety performance occurred on the lineal freeway sections and at full to partial design locations. An observed decrease in safety performance was not found at the partial plus to partial lighting design modifications. Title: Understanding the Safety Effects of Roadway Illumination Reductions Author: Monsere, Christopher M., Yin, Thareth, Wolfe, Michael Year: 2007 In 2001, Oregon’s governor responded to a perceived future energy shortage in the Pacific Northwest by directing all state agencies to reduce power consumption by 10 percent. After review of power saving opportunities, the Oregon Department of Transportation (ODOT) elected to include selective illumination reductions on Oregon interstate highways as part of their energy saving strategy. The illumination reductions occurred at interchanges and along lineal highway sections between October 2001 and April 2002. A total of 47 interchanges and 6.03 miles of interstate highways were modified. Changes in illumination were broadly classified as either full (including high-mast) to partial designs, partial plus to partial designs, or lineal reductions. In this study, no before or after field measurements were taken of actual luminance values, lighting coverage, or other design specific values. This research evaluated the changes in safety performance using crash, geometry, weather and volume data from years 1996 to 2005 using observational before-after evaluations using the : 1) the simple before-after and 2) empirical-bayes approach. The empirical-bayes approach found a 3.47 percent increase (4.65 standard deviation) in total night crashes where full interchange lighting was reduced to partial lighting. Fatal and injury night crashes, however, were found to decrease by 11.38%. For interchanges where illumination was reduced from partial plus to partial, a 35.24 percent decrease in total night crashes was found. A 29 percent increase in total night crashes (18.21 standard deviation) on sections where the lineal lighting was modified was found. Weighing all evidence, the research concludes that a decrease in safety performance occurred on the lineal freeway sections and at full to partial design locations. An observed decrease in safety performance was not found at the partial plus to partial lighting design modifications. Close

• 7. [Article] Analysis of the Impacts of Transit Signal Priority on Bus Bunching and Performance

  Efficient and reliable public transit systems provide opportunities to reduce congestion, emissions in urban areas and provide access and mobility to residents. Headway, or the time difference between ...

  Citation × Citation Citation Abstract Copy Title: Analysis of the Impacts of Transit Signal Priority on Bus Bunching and Performance Author: Albright, Eric, Figliozzi, Miguel Andres Year: 2012 Efficient and reliable public transit systems provide opportunities to reduce congestion, emissions in urban areas and provide access and mobility to residents. Headway, or the time difference between departing or arriving vehicles, is a useful measure to gauge bus transit performance; because short headways can lead to bus bunching incidents that quickly degrade transit level of service. While Transit Signal Priority (TSP) has been shown to decrease travel time and delay experienced by buses, little work has shown how TSP may affect bus bunching. This research attempts to understand the characteristics of bus trips, especially TSP, that prevent or promote short headways, or bus bunching. A study of two transit routes in SE Portland is presented. High values of negative serial correlation were observed among consecutive headway observations. A regression model is used to analyze factors (boardings, alightings, stops, lift usage, Transit Signal Priority and direction of travel) that may influence bus headways. Priority requests are shown to have a significant effect on headways. Title: Analysis of the Impacts of Transit Signal Priority on Bus Bunching and Performance Author: Albright, Eric, Figliozzi, Miguel Andres Year: 2012 Efficient and reliable public transit systems provide opportunities to reduce congestion, emissions in urban areas and provide access and mobility to residents. Headway, or the time difference between departing or arriving vehicles, is a useful measure to gauge bus transit performance; because short headways can lead to bus bunching incidents that quickly degrade transit level of service. While Transit Signal Priority (TSP) has been shown to decrease travel time and delay experienced by buses, little work has shown how TSP may affect bus bunching. This research attempts to understand the characteristics of bus trips, especially TSP, that prevent or promote short headways, or bus bunching. A study of two transit routes in SE Portland is presented. High values of negative serial correlation were observed among consecutive headway observations. A regression model is used to analyze factors (boardings, alightings, stops, lift usage, Transit Signal Priority and direction of travel) that may influence bus headways. Priority requests are shown to have a significant effect on headways. Close

• 8. [Article] Trace Metals in Stormwater: Alternative Best Management Practices

  Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate ...

  Citation × Citation Citation Abstract Copy Title: Trace Metals in Stormwater: Alternative Best Management Practices Author: Mora, Jennifer Ibeth Year: 2017 Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate the heavy metal (Cu and Zn) removal efficiency of perlite and EarthliteTM to improve in-situ filtration systems for stormwater catchment basins. Stormwater samples from two field sites in Portland, OR, chosen to represent a high-use commercial site and high-traffic urban road, were characterized to inform experimental design and compare to values found in literature. The Linear, Freundlich, and Langmuir isotherm models were used to describe equilibrium data and determine partitioning coefficients for single metal batch studies. Both the Freundlich and Langmuir models fit most single metal batch systems, while Cu-Perlite, Zn-Perlite, and Zn-EarthliteTM, were best fit by the Langmuir model, R2 = 0.9594; 0.9538; 0.9811, respectively. Competitive adsorption behaviors for Cu and Zn were evaluated using a synthetic stormwater recipe where relative concentrations of Cu and Zn were maintained to be consistent with representative stormwater samples. Perlite showed a decrease in the sorption capacity of Cu and Zn in the presence of competing ions in solution. EarthliteTM showed no difference in the affinity for copper uptake between competitive and non-competitive batch experiments. EarthliteTM affinity for Zn decreased by two orders of magnitude in the competitive batch system. The results from this study will be applied to estimate filter lifetime for traditional and advanced stormwater filter systems. These results will inform experimental design in dynamic flow-through experiments using various filter media thereby improving filter design and implementation of stormwater best management practices. Title: Trace Metals in Stormwater: Alternative Best Management Practices Author: Mora, Jennifer Ibeth Year: 2017 Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate the heavy metal (Cu and Zn) removal efficiency of perlite and EarthliteTM to improve in-situ filtration systems for stormwater catchment basins. Stormwater samples from two field sites in Portland, OR, chosen to represent a high-use commercial site and high-traffic urban road, were characterized to inform experimental design and compare to values found in literature. The Linear, Freundlich, and Langmuir isotherm models were used to describe equilibrium data and determine partitioning coefficients for single metal batch studies. Both the Freundlich and Langmuir models fit most single metal batch systems, while Cu-Perlite, Zn-Perlite, and Zn-EarthliteTM, were best fit by the Langmuir model, R2 = 0.9594; 0.9538; 0.9811, respectively. Competitive adsorption behaviors for Cu and Zn were evaluated using a synthetic stormwater recipe where relative concentrations of Cu and Zn were maintained to be consistent with representative stormwater samples. Perlite showed a decrease in the sorption capacity of Cu and Zn in the presence of competing ions in solution. EarthliteTM showed no difference in the affinity for copper uptake between competitive and non-competitive batch experiments. EarthliteTM affinity for Zn decreased by two orders of magnitude in the competitive batch system. The results from this study will be applied to estimate filter lifetime for traditional and advanced stormwater filter systems. These results will inform experimental design in dynamic flow-through experiments using various filter media thereby improving filter design and implementation of stormwater best management practices. Close

• 9. [Article] Molecular View Modeling of Atmospheric Organic Particulate Matter: Incorporating Molecular Structure and Co-Condensation of Water

  Most urban and regional models used to predict levels of organic particulate matter (OPM) are based on fundamental equations for gas/particle partitioning, but make the highly simplifying, anonymized-view ...

  Citation × Citation Citation Abstract Copy Title: Molecular View Modeling of Atmospheric Organic Particulate Matter: Incorporating Molecular Structure and Co-Condensation of Water Author: Pankow, James F., Marks, Marguerite Colasurdo, Barsanti, Kelley C., Mahmud, Abdullah, Asher, William E., Li, Jingyi, Ying, Qi, Jathar, Shantanu H., Kleeman, Michael J. Year: 2015 Most urban and regional models used to predict levels of organic particulate matter (OPM) are based on fundamental equations for gas/particle partitioning, but make the highly simplifying, anonymized-view (AV) assumptions that OPM levels are not affected by either: a) the molecular. characteristics of the condensing organic compounds (other than simple volatility); or b) co-condensation of water as driven by non-zero relative humidity (RH) values. The simplifying assumptions have allowed parameterized chamber results for formation of secondary organic aerosol (SOA) (e.g., “two-product” (2p) coefficients) to be incorporated in chemical transport models. However, a return towards a less simplistic (and more computationally demanding) molecular view (MV) is needed that acknowledges that atmospheric OPM is a mixture of organic compounds with differing polarities, water, and in some cases dissolved salts. The higher computational cost of MV modeling results from a need for iterative calculations of the composition-dependent gas/particle partition coefficient values. MV modeling of OPM that considered water uptake (but not dissolved salts) was carried out for the southeast United States for the period August 29 through September 7, 2006. Three model variants were used at three universities: CMAQ-RH-2p (at PSU), UCD/CIT-RH-2p (at UCD), and CMAQ-RH-MCM (at TAMU). With the first two, MV structural characteristics (carbon number and numbers of functional groups) were assigned to each of the 2p products used in CMAQv.4.7.1 such that resulting predicted Kp,i values matched those in CMAQv.4.7.1. When water uptake was allowed, most runs assumed that uptake occurred only into the SOA portion, and imposed immiscibility of SOA with primary organic aerosol (POA). (POA is often viewed as rather non-polar, while SOA is commonly viewed as moderately-to-rather polar. Some runs with UCD/CIT-RH-2p were used to investigate the effects of POA/SOA miscibility.) CMAQ-RH-MCM used MCM to generate oxidation products, and assumed miscibility of SOA and POA. In a ∼500 km wide band from Louisiana through to at least North Carolina, CMAQ-RH-2p and UCD/CIT-RH-2p predicted that water uptake can increase SOA levels by as much as 50 to 100% (from a range of ∼1 to 2 μg m-3 to a range of ∼1 to 4 μg m-3). CMAQ-RH-MCM predicted much lower effects of water uptake on SOA levels (<10% increase). The results from CMAQ-RH-2p and UCD/CIT-RH-2p are considered more reflective of reality. In the Alabama/Georgia hotspot, both CMAQ-RH-2p and UCD/CIT-RH-2p predicted aerosol water levels that are up to nearly half the predicted SOA levels, namely ∼0.5 to 2 μg m-3. Such water levels in SOA will affect particle optical properties, viscosity, gas/particle partitioning times, and rates of hydrolysis and water elimination reactions. Title: Molecular View Modeling of Atmospheric Organic Particulate Matter: Incorporating Molecular Structure and Co-Condensation of Water Author: Pankow, James F., Marks, Marguerite Colasurdo, Barsanti, Kelley C., Mahmud, Abdullah, Asher, William E., Li, Jingyi, Ying, Qi, Jathar, Shantanu H., Kleeman, Michael J. Year: 2015 Most urban and regional models used to predict levels of organic particulate matter (OPM) are based on fundamental equations for gas/particle partitioning, but make the highly simplifying, anonymized-view (AV) assumptions that OPM levels are not affected by either: a) the molecular. characteristics of the condensing organic compounds (other than simple volatility); or b) co-condensation of water as driven by non-zero relative humidity (RH) values. The simplifying assumptions have allowed parameterized chamber results for formation of secondary organic aerosol (SOA) (e.g., “two-product” (2p) coefficients) to be incorporated in chemical transport models. However, a return towards a less simplistic (and more computationally demanding) molecular view (MV) is needed that acknowledges that atmospheric OPM is a mixture of organic compounds with differing polarities, water, and in some cases dissolved salts. The higher computational cost of MV modeling results from a need for iterative calculations of the composition-dependent gas/particle partition coefficient values. MV modeling of OPM that considered water uptake (but not dissolved salts) was carried out for the southeast United States for the period August 29 through September 7, 2006. Three model variants were used at three universities: CMAQ-RH-2p (at PSU), UCD/CIT-RH-2p (at UCD), and CMAQ-RH-MCM (at TAMU). With the first two, MV structural characteristics (carbon number and numbers of functional groups) were assigned to each of the 2p products used in CMAQv.4.7.1 such that resulting predicted Kp,i values matched those in CMAQv.4.7.1. When water uptake was allowed, most runs assumed that uptake occurred only into the SOA portion, and imposed immiscibility of SOA with primary organic aerosol (POA). (POA is often viewed as rather non-polar, while SOA is commonly viewed as moderately-to-rather polar. Some runs with UCD/CIT-RH-2p were used to investigate the effects of POA/SOA miscibility.) CMAQ-RH-MCM used MCM to generate oxidation products, and assumed miscibility of SOA and POA. In a ∼500 km wide band from Louisiana through to at least North Carolina, CMAQ-RH-2p and UCD/CIT-RH-2p predicted that water uptake can increase SOA levels by as much as 50 to 100% (from a range of ∼1 to 2 μg m-3 to a range of ∼1 to 4 μg m-3). CMAQ-RH-MCM predicted much lower effects of water uptake on SOA levels (<10% increase). The results from CMAQ-RH-2p and UCD/CIT-RH-2p are considered more reflective of reality. In the Alabama/Georgia hotspot, both CMAQ-RH-2p and UCD/CIT-RH-2p predicted aerosol water levels that are up to nearly half the predicted SOA levels, namely ∼0.5 to 2 μg m-3. Such water levels in SOA will affect particle optical properties, viscosity, gas/particle partitioning times, and rates of hydrolysis and water elimination reactions. Close

• 10. [Article] Particle Trapping in Stratified Estuaries - Definition of a Parameter Space

  Estuarine turbidity maxima (ETM) retain suspended particulate matter (SPM) through advection, settling, aggregation and non-linearities in bed processes. This contribution defines for the first time a ...

  Citation × Citation Citation Abstract Copy Title: Particle Trapping in Stratified Estuaries - Definition of a Parameter Space Author: Jay, David A., Orton, Philip M., Chisholm, Thomas A., Wilson, Douglas J., Fain, Annika M., McGinity, John Year: 2003 Estuarine turbidity maxima (ETM) retain suspended particulate matter (SPM) through advection, settling, aggregation and non-linearities in bed processes. This contribution defines for the first time a parameter space descriptive of ETM water-column particle trapping processes through a scaling analysis of the local and integral SPM balances. In the absence of long-term deposition, there are five primary parameters for the large particles or aggregates that are typically trapped. Rouse number P, the ratio of settling velocity WS of the SPM relative to the shear velocity U*, describes the material trapped in the ETM in terms of the local vertical balance between vertical mixing and aggregate settling. Advection number A= P ΔU/UT scales the landward transport of SPM by tidal and mean flow processes in terms of flood-ebb velocity difference (ΔU) and maximum tidal current (UT). Supply number SR = P UR/UT defines SPM supply and removal (UR is river flow). Changes in the estuarine inventory of SPM are described in terms of a Trapping Efficiency E, a ratio of peak ETM concentration to fluvial or marine supply concentration. The effects of aggregation in the integral dynamic balance are quantified by a Floc number F that describes the tendency of aggregates to form through shear-driven collisions. This study uses observations from two strongly advective systems (the Columbia and Fraser Rivers) plus literature values from 13 other estuaries to illustrate the applicability of the above scaling. The primary question investigated is the relationship of trapping efficiency E and Floc number F to other parameters, especially river flow (expressed in terms of supply number SR). The strongest SPM trapping (high E) occurs in mid-ETM, where A ~0. The extreme high flows observed in the Fraser River estuary show how ETM trapping becomes ineffective as the estuary length contracts to one tidal excursion or less (limit of high SR). Use of data from all 15 estuaries shows that there is a strong trend toward more efficient trapping for low SR. E and F are positively correlated, so that aggregation becomes more prominent in systems with weak to moderate river flow. Examination of tidal monthly and seasonal particle properties at four closely-spaced moorings in the Columbia emphasize the importance of strong ETM gradients – particle properties are diverse even when the hydrodynamic regime is apparently similar. Finally, scaling variables and data are combined to express ETM properties in terms of U*, UR and UT.. Title: Particle Trapping in Stratified Estuaries - Definition of a Parameter Space Author: Jay, David A., Orton, Philip M., Chisholm, Thomas A., Wilson, Douglas J., Fain, Annika M., McGinity, John Year: 2003 Estuarine turbidity maxima (ETM) retain suspended particulate matter (SPM) through advection, settling, aggregation and non-linearities in bed processes. This contribution defines for the first time a parameter space descriptive of ETM water-column particle trapping processes through a scaling analysis of the local and integral SPM balances. In the absence of long-term deposition, there are five primary parameters for the large particles or aggregates that are typically trapped. Rouse number P, the ratio of settling velocity WS of the SPM relative to the shear velocity U*, describes the material trapped in the ETM in terms of the local vertical balance between vertical mixing and aggregate settling. Advection number A= P ΔU/UT scales the landward transport of SPM by tidal and mean flow processes in terms of flood-ebb velocity difference (ΔU) and maximum tidal current (UT). Supply number SR = P UR/UT defines SPM supply and removal (UR is river flow). Changes in the estuarine inventory of SPM are described in terms of a Trapping Efficiency E, a ratio of peak ETM concentration to fluvial or marine supply concentration. The effects of aggregation in the integral dynamic balance are quantified by a Floc number F that describes the tendency of aggregates to form through shear-driven collisions. This study uses observations from two strongly advective systems (the Columbia and Fraser Rivers) plus literature values from 13 other estuaries to illustrate the applicability of the above scaling. The primary question investigated is the relationship of trapping efficiency E and Floc number F to other parameters, especially river flow (expressed in terms of supply number SR). The strongest SPM trapping (high E) occurs in mid-ETM, where A ~0. The extreme high flows observed in the Fraser River estuary show how ETM trapping becomes ineffective as the estuary length contracts to one tidal excursion or less (limit of high SR). Use of data from all 15 estuaries shows that there is a strong trend toward more efficient trapping for low SR. E and F are positively correlated, so that aggregation becomes more prominent in systems with weak to moderate river flow. Examination of tidal monthly and seasonal particle properties at four closely-spaced moorings in the Columbia emphasize the importance of strong ETM gradients – particle properties are diverse even when the hydrodynamic regime is apparently similar. Finally, scaling variables and data are combined to express ETM properties in terms of U*, UR and UT.. Close