The NC State Repository is a node in the research infrastructure that gathers and makes visible online intellectual outputs of the NC State University research and learning community. The Libraries works with university departments, units and individuals to curate, describe, and make accessible products of research and intellectual effort through a series of services, including:
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Estimating Alveolar Ventilation for Use in Physiological-based Exposure Models
The United States Environmental Protection Agency (EPA) utilizes the Air Pollutants Exposure (APEX) model to estimate exposure to criteria air pollutants such as carbon monoxide (CO), to inform the setting of air quality standards (e.g., US EPA, 2010). The data for estimating alveolar ventilation rates (𝑉 ̇𝐴) in this model used for modeling CO exposures and dose was last updated over 20 years ago and could benefit from additional information extracted from new studies as well as performing additional data analysis. Specifically, the existing constant value used in the equation to estimate 𝑉 ̇𝐴, 19.63, has been raised by public reviewers of the most recent CO human health risk and exposure assessment as potentially limited in its applicability, particularly at when simulated individuals are high breathing rates (US EPA, 2011). This new study was conducted to increase our knowledgebase of the physiological aspects of ventilation and to further develop an internal alveolar ventilation database that could be used to either support the existing quantitative linear relationship or, where possible, improve the algorithm. This evaluation also explored the relationship of how alveolar ventilation with might be affected by key demographic attributes such as body mass, age, and sex. Two approaches were explored to estimate 𝑉 ̇𝐴 and are linked to key respiratory variables already modeled by APEX. The first, used a direct relationship between 𝑉 ̇𝐴 and oxygen consumption rates (𝑉 ̇𝑂2). The second used the relationship of dead space to tidal volume (VD/VT) to 𝑉 ̇𝑂2 and expected to be used with total ventilation rate (𝑉 ̇𝐸) to indirectly estimate 𝑉 ̇𝐴. This study increased the amount of useful data within the internal database by over two-fold, albeit sample size limitations for important population groups remain an issue (e.g., adults > 35 years old). New data analyses using the updated database suggest a linear relationship between 𝑉 ̇𝐴 and 𝑉 ̇𝑂2 appears appropriate across all population groups and breathing rates, while differences in the VD/VT to 𝑉 ̇𝑂2 relationship across 3 population groups suggests adoption of this latter approach is less likely due to the sample size issues. It is hoped study results assist in the development of a newly refined algorithm to for estimating CO exposure and dose estimations, reduce uncertainties in exposure models that would use such an approach, and provide sound support to air quality regulations.
Expanding the Conservation Reserve Program to Promote Habitat Conservation at Hazardous Waste Cleanup Sites: A Feasibility Study
Remediation of former hazardous waste sites generates a new opportunity for lands contaminated with regulated hazardous waste. Many sites across the United States are remediated under the Resource Conservation and Recovery Act (RCRA) Corrective Action Program with a primary focus to eliminate human health and ecological risks associated with the improper handling, disposal, and/or treatment of hazardous waste and find a beneficial reuse for the site. The primary focus of this study examines the potential reuse of a remediated corrective action site through the United States Department of Agriculture’s Conservation Reserve Program (CRP). The study considered two outcomes, (1) converting a remediated corrective action site to pollinator habitat under the CRP framework would benefit both the site owner and surrounding ecosystem and (2) that the cost associated with pollinator habitat development would outweigh the financial incentives of the CRP lease. The study site is located in southern Missouri, with corrective action now in post-closure care; however, site use restrictions remain in place due to soil “hot spots” throughout the site. The site use restrictions have made resale of the site difficult for the current owner and limits redevelopment opportunities. This study examined converting selected acreage into a conservation resource under the framework established USDA CRP. CRP enrollment is currently limited to privately owned agricultural land, where landowners receive a payment incentive in the form of a lease payment to convert previously cropped land into non-cropped conservation land. Specifically, this study explored enrollment opportunity under the Continuous CRP for establishing pollinator and wildlife habitat. The feasibility of expanding the CRP to include corrective action sites is explored in the form of a financial analysis. The study found that the financial benefit to the current landowner is significant and there is potential to establish over 200-acres of new pollinator and wildlife habitat on a parcel of land that currently provides limited economic and environmental benefit.
Estuarine Shoreline Stabilization Methods in Coastal North Carolina: a Case Study Analysis of Coastal Resiliency
Coastal North Carolina estuaries provide countless environmental and economic benefits to the state of North Carolina. These valuable ecosystems along the coast are very diverse in nature and are home to thousands of different species that attract much of the state’s tourism industry and provide an important resource to local economies. With recent pressures on these estuaries from increasing development and boat traffic in coastal communities, combined with more frequent and intense storm systems driven by climate change, a focus on coastal resiliency is at the forefront in our state. The push towards long term coastal resiliency planning in North Carolina has been fostered through partnerships and programs implemented by non- profit foundations, local, state, and federal governments, and other organizations, with the goal of protecting and enhancing the countless benefits that these estuaries provide. To better analyze the current methods and practices being implemented in our coastal communities as a foundation in North Carolina’s coastal resiliency efforts, pre- and post-storm observations from existing projects are evaluated and discussed. Evaluating the effectiveness of current coastal resiliency practices in North Carolina can provide an important role in future planning efforts for our coastal communities to reduce negative impacts from future storms.