College of Natural Resources and Environment (CNRE)
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Browsing College of Natural Resources and Environment (CNRE) by Department "Civil and Environmental Engineering"
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- Effects of Large Wood on Floodplain Connectivity in a Headwater Mid-Atlantic StreamKeys, Tyler A.; Governer, Heather; Jones, C. Nathan; Hession, W. Cully; Hester, Erich T.; Scott, Durelle T. (2018-05-08)Large wood (LW) plays an essential role in aquatic ecosystem health and function. Traditionally, LW has been removed from streams to minimize localized flooding and increase conveyance efficiency. More recently, LW is often added to streams as a component of stream and river restoration activities. While much research has focused on the role of LW in habitat provisioning, geomorphic stability, and hydraulics at low to medium flows, we know little about the role of LW during storm events. To address this question, we investigated the role of LW on floodplain connectivity along a headwater stream in the Mid-Atlantic region of the United States. Specifically, we conducted two artificial floods, one with and one without LW, and then utilized field measurements in conjunction with hydrodynamic modeling to quantify floodplain connectivity during the experimental floods and to characterize potential management variables for optimized restoration activities. Experimental observations show that the addition of LW increased maximum floodplain inundation extent by 34%, increased floodplain inundation depth by 33%, and decreased maximum thalweg velocity by 10%. Model results demonstrated that different placement of LW along the reach has the potential to increase floodplain flow by up to 40%, with highest flooding potential at cross sections with high longitudinal velocity and shallow depth. Additionally, model simulations show that the effects of LW on floodplain discharge decrease as storm recurrence interval increases, with no measurable impact at a recurrence interval of more than 25 years.
- Environmental health disparities in the Central Appalachian region of the United StatesKrometis, Leigh-Anne H.; Gohlke, Julia M.; Kolivras, Korine N.; Satterwhite, Emily M.; Marmagas, Susan West; Marr, Linsey C. (De Gruyter, 2017-09-26)Health disparities that cannot be fully explained by socio-behavioral factors persist in the Central Appalachian region of the United States. A review of available studies of environmental impacts on Appalachian health and analysis of recent public data indicates that while disparities exist, most studies of local environmental quality focus on the preservation of nonhuman biodiversity rather than on effects on human health. The limited public health studies available focus primarily on the impacts of coal mining and do not measure personal exposure, constraining the ability to identify causal relationships between environmental conditions and public health. Future efforts must engage community members in examining all potential sources of environmental health disparities to identify effective potential interventions.
- Occupational Safety and Health Concerns in Logging: A Cross-Sectional Assessment in VirginiaKim, Sunwook; Nussbaum, Maury A.; Schoenfisch, Ashley L.; Barrett, Scott M.; Bolding, M. Chad; Dickerson, Deborah E. (MDPI, 2017-11-15)Increased logging mechanization has helped improve logging safety and health, yet related safety risks and concerns are not well understood. A cross-sectional study was completed among Virginia loggers. Participants n = 122) completed a self-administered questionnaire focusing on aspects of safety and health related to logging equipment. Respondents were at a high risk of workplace injuries, with reported career and 12-month injury prevalences of 51% and 14%, respectively. Further, nearly all (98%) respondents reported experiencing musculoskeletal symptoms. Over half (57.4%) of respondents reported symptoms related to diesel exhaust exposure in their career. Few (15.6%), however, perceived their jobs to be dangerous. Based on the opinions and suggestions of respondents, three priority areas were identified for interventions: struck-by/against hazards, situational awareness (SA) during logging operations, and visibility hazards. To address these hazards, and to have a broader and more substantial positive impact on safety and health, we discuss the need for proactive approaches such as incorporating proximity technologies in a logging machine or personal equipment, and enhancing logging machine design to enhance safety, ergonomics, and SA.
- Predicting Solute Transport Through Green Stormwater Infrastructure With Unsteady Transit Time Distribution TheoryParker, E. A.; Grant, Stanley B.; Cao, Y.; Rippy, Megan A.; McGuire, Kevin J.; Holden, P. A.; Feraud, M.; Avasarala, S.; Liu, H.; Hung, W. C.; Rugh, M.; Jay, J.; Peng, J.; Shao, S.; Li, D. (2021-02)In this study, we explore the use of unsteady transit time distribution (TTD) theory to model solute transport in biofilters, a popular form of nature-based or "green" storm water infrastructure (GSI). TTD theory has the potential to address many unresolved challenges associated with predicting pollutant fate and transport through these systems, including unsteadiness in the water balance (time-varying inflows, outflows, and storage), unsteadiness in pollutant loading, time-dependent reactions, and scale-up to GSI networks and urban catchments. From a solution to the unsteady age conservation equation under uniform sampling, we derive an explicit expression for solute breakthrough during and after one or more storm events. The solution is calibrated and validated with breakthrough data from 17 simulated storms at a field-scale biofilter test facility in Southern California, using bromide as a conservative tracer. TTD theory closely reproduces bromide breakthrough concentrations, provided that lateral exchange with the surrounding soil is accounted for. At any given time, according to theory, more than half of the water in storage is from the most recent storm, while the rest is a mixture of penultimate and earlier storms. Thus, key management endpoints, such as the pollutant treatment credit attributable to GSI, are likely to depend on the evolving age distribution of water stored and released by these systems.
- Preparation and evaluation of nanocellulose-gold nanoparticle nanocomposites for SERS applicationsWei, Haoran; Rodriguez, Katia; Renneckar, Scott; Leng, Weinan; Vikesland, Peter J. (The Royal Society of Chemistry, 2015-06-09)Nanocellulose is of research interest due to its extraordinary optical, thermal, and mechanical properties. The incorporation of guest nanoparticles into nanocellulose substrates enables production of novel nanocomposites with a broad range of applications. In this study, gold nanoparticle/bacterial cellulose (AuNP/BC) nanocomposites were prepared and evaluated for their applicability as surface-enhanced Raman scattering (SERS) substrates. The nanocomposites were prepared by citrate mediated in situ reduction of Au3+ in the presence of a BC hydrogel at 303 K. Both the size and morphology of the AuNPs were functions of the HAuCl4 and citrate concentrations. At high HAuCl4 concentrations, Au nanoplates form within the nanocomposites and are responsible for high SERS enhancements. At lower HAuCl4 concentrations, uniform nanospheres form and the SERS enhancement is dependent on the nanosphere size. The time-resolved increase in the SERS signal was probed as a function of drying time with SERS ‘hot-spots’ primarily forming in the final minutes of nanocomposite drying. The application of the AuNP/BC nanocomposites for detection of the SERS active dyes MGITC and R6G as well as the environmental contaminant atrazine is illustrated as is its use under low and high pH conditions. The results indicate the broad applicability of this nanocomposite for analyte detection.