Browsing by Author "Richardson, Curtis J"
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Item Open Access A Land Management Plan for the Galveston Bay Foundation's Texas City Property(2008-04-25T18:35:55Z) Ward, AmandaAs a land trust, the Galveston Bay Foundation holds conservation easements and also owns several thousand acres of coastal land in the four county region surrounding the Galveston Bay in Texas. The foundation accepted a conservation easement as well as full ownership of this 132.2 acre (53.5HA) wetland mitigation property in 2005. This management plan will serve to educate staff and board members on the history of this property and potential issues of interest for the management of this land. The property has a coastal prairie upland with 42.6 acres (17.24 HA) of created wetlands. The wetlands were created as required by a United States Army Corps of Engineers permit for a project that destroyed wetlands on another site. Over the past three years the site has become re-vegetated with an assortment of wetland plant species and the created wetlands maintain natural water conditions as planned. The property was placed under a conservation easement to ensure that it would be preserved in as natural a condition as possible forever; however, as the foundation owns the land and was the recipient of the conservation easement it appears that the easement may not be valid. Therefore, either a new easement should be signed with another land trust, or the land should be sold to a conservation buyer with the Galveston Bay Foundation holding the easement. Chinese Tallow (Sapium sebiferum), a prevalent invasive species in the region, will need to be managed and other invasive species invasions should be prevented. There are public use structures on the western tract of the property which imply that the public may visit the site which will require clear public use policies. Fencing may be considered on the eastern portion of the property to prevent trespassing and additional signage should be placed to advertise GBF’s ownership of the land.Item Open Access A Macroinvertebrate Survey of Sandy Creek in Durham County, NC: A Comparative Study of Post-Restoration and Pre-Restoration Surveys(2009-04-17T20:07:32Z) Still, JeanSandy Creek, located within the Cape Fear watershed within the Triassic Basin of North Carolina, is a first order stream within a tributary watershed that feeds into Jordan Lake reservoir. A biological assessment, following the NCDENR Benthic Standard Operating Procedure, was performed and all macroinvertebrates were identified at three sites over three months within the upper Sandy Creek watershed within Duke University Wetland Center’s Stream and Wetland Assessment Management Park (SWAMP). This was done three years post-restoration in 2008. Mud Creek, Sandy Creek’s reference stream, was also sampled in 2008. This bioassessment was performed as a follow up to the baseline macroinvertebrate survey completed pre-restoration in 2004/2005 and to determine the restoration’s effect on its macroinvertebrates and water quality. The biotic index values calculated from the pre-restoration and post-restoration macroinvertebrate tolerance and abundance levels indicated a decrease in biotic index value or an increase in water quality (6.7 pre-restoration to 6.4 post-restoration). The biotic index values calculated for the three post-restoration sites show a water quality improvement as the water flows through the restoration (6.58 input to 6.434 midpoint to 6.42output) which may indicate that the restoration is increasing stream function. The macroinvertebrate orders and feeding types that were collected provided additional information on the difference between pre- and post-restoration Sandy Creek.Item Open Access An Assessment of Sustainable Water Management at University Campuses(2011) McHugh, Amani NSustainable water management is needed to ensure quality supplies of our vital water resources in the face of growing human demand for water, high levels of pollution, and increasing spatial and temporal variability associated with climate change. An integrated approach to water management is recommended to address current water challenges, which are often interrelated with other environmental, economic and social issues. Universities and colleges have missions, resources, and contexts that could enable them to lead the process of developing and applying sustainable and integrated water resource management (IWRM). The opportunity to exemplify integrated water management has grown as institutions of higher education have made progress towards incorporating environmental sustainability into teaching, research, and campus operations. This dissertation examines the issue of campus water management at institutions of higher education through a review of campus sustainability literature, a survey of sustainability and facilities managers, and case studies of three campus water-related projects.
Findings from the review of campus sustainability literature and websites suggests water is less of a campus management priority than issues such as energy and climate change; furthermore, where water is addressed, the focus is on water conservation, while water quality management is overlooked. IWRM is not explicitly discussed in the campus sustainability literature reviewed, though principles relevant to IWRM are included in some campus sustainability declarations and programs. Results from the survey substantiate the findings from literature review that water management is less of an institutional priority than energy management and water quality management is often underemphasized in campus management. According to the survey respondents, campus water management at the institutions represented was on average just adequately managed and institutions were minimally prepared to deal with several types of future water problems. Facilities managers tended to rate their institution's water management as slightly more effective compared to sustainability coordinators. Many campuses relied on top-down, engineering based water management approaches, rather than integrated and interdisciplinary water management. Individual initiatives, municipal codes and policies, campus community sustainability awareness, and campus environmental projects served as drivers for more sustainable water management, while budget constrains were a common barrier. Logistic regression analysis of the survey data revealed that institutions featuring stream and wetland restoration projects had greater odds of being described as having a developed watershed plan and taking into consideration multidisciplinary approaches to water management.
Case studies showed that wetland creation and restoration projects can serve as effective teaching and research laboratories for institutions of higher education, but that none of the studied cases fully exemplified IWRM in their operation. Of the three cases studied, the Stream and Wetland Assessment Management Park project at Duke University most closely demonstrated a campus project designed and developed to address water problems in the campus watershed, while also offering an effective outdoor teaching and research laboratory for hundreds of students, professionals, and researchers. The Olentangy River Wetland Research Park case at Ohio State University exemplified the potential for wetland creation and restoration projects to serve as a facility for educating thousands of students and visitors, training dozens of water experts, and influencing wetland and water resource management beyond the campus. The Radford University Stormwater Treatment Wetland Project case illustrated the potential for institutions with limited space and resources to establish effective outdoor teaching laboratories using environmental features already present or in development on campus.
Findings from the review, survey and case studies all point toward the need and opportunity for institutions of higher education to make greater efforts at implementing and promoting sustainable and integrated water resource management. Literature review and survey findings reveal that water is frequently overlooked as environmental resource at universities and colleges, while other environmental issues such as energy, climate change and recycling are prioritized in sustainability plans and efforts. Universities and colleges have made progress addressing water conservation, while water quality and stormwater need further attention and an integrated approach for more effective management.
Item Open Access An ecological perspective on nanomaterial impacts in the environment.(J Environ Qual, 2010-11) Bernhardt, Emily S; Colman, Benjamin P; Hochella, Michael F; Cardinale, Bradley J; Nisbet, Roger M; Richardson, Curtis J; Yin, LiyanGrowing concerns over the potential for unintended, adverse consequences of engineered nanoparticles (ENPs) in the environment have generated new research initiatives focused on understanding the ecological effects of ENPs. Almost nothing is currently known about the fate and transport of ENPs in environmental waters, soils, and sediments or about the biological impacts of ENPs in natural environments, and the bulk of modern nanotoxicogical research is focused on highly controlled laboratory studies with single species in simple media. In this paper, we provide an ecological perspective on the current state of knowledge regarding the likely environmental impacts of nanomaterials and propose a strategy for making rapid progress in new research in ecological nanoscience.Item Open Access Assessing Nutrient Retention of Restored Wetlands in North Carolina(2019-04-25) Bognar, Sebastian; Chen, Siying; Lanier, SarahWetlands are among the most productive and dynamic ecosystems in the world; biogeochemical cycling and storage processes are crucial for nutrient retention in wetland systems. This study aims to test if restored wetlands improve downstream water quality by reducing nutrient concentrations, to determine which variables are important for nutrient retention, and to analyze the temporal trend of wetland nutrient retention. We gathered water quality data from three locations in North Carolina, for a total of 13 restored and constructed wetlands. We compared nitrogen and phosphorous concentrations in the inflow and outflow of each wetland and determined the significance of other categorical and continuous variables. The results of our study can help ascertain the most important variables for choosing potential wetland restoration sites, and lead to a better understanding of how nutrient removal changes over time.Item Open Access Comparison of streambed texture and hydraulic conductivity between degraded, natural reference, enhanced, and restored streams in the New Hope Creek watershed in Durham, North Carolina(2017-04-28) Crowell, Breanna; Fowler, Jerrett; Lenart, Jennifer; Smith, AustonCritical links exist between stream channel attributes and water quality function within stream restorations. During the process of stream restoration, much attention goes into recreating the profile of natural reference stream channels, but far less attention is given to factors that affect characteristics of the hyporheic zone in restored streambeds. The Priority 1 restoration process typically requires filling in the existing unstable stream channel and creating a new channel in the adjacent floodplain. The restoration of urban streams is often confined spatially and economically, so one alternative method includes stream enhancements that occur entirely with the stream channel. For this analysis, six streams – two natural, one degraded, one enhanced, and two restored -- near Durham, North Carolina were selected for textural and hydraulic conductivity analysis to identify the potential for hyporheic functions within these different systems. While direct measurement of hyporheic exchange is a complex process that is often not feasible stream restoration evaluation, there are several relatively simple indicators of potential hyporheic exchange including soil texture and field permeameter measurements. The study seeks to answer two questions: (1) Is there a difference in streambed sediment texture between degraded, natural reference, enhanced, and Priority 1 restored streams and within the vertical profile of a streambed? (2) How does streambed hydraulic conductivity relate to sediment texture in a stream system? This analysis relates three main findings in relation to streambed sediment texture and permeability. First, twenty-five percent of the measured variation in hydraulic conductivity of a streambed is explained by clay. Second, Priority 1 restorations do initially lose permeability and potentially hyporheic functionality, and this may take around ten years to be recovered in a new channel. Third, despite a higher cost per linear foot in Priority 1 restorations, the additional benefits provided by this method could outweigh this initial expense. Streambed sediment texture is not the only factor in explaining hyporheic functionality, but is a key component to whether the hyporheic zone can exist. Managers should consider the texture of a new channel when restorations are completed as it may relate to how functionality will be regained in the system.Item Open Access Connecting differential responses of native and invasive riparian plants to climate change and environmental alteration.(Ecol Appl, 2015-04) Flanagan, Neal E; Richardson, Curtis J; Ho, MengchiClimate change is predicted to impact river systems in the southeastern United States through alterations of temperature, patterns of precipitation and hydrology. Future climate scenarios for the southeastern United States predict (1) surface water temperatures will warm in concert with air temperature, (2) storm flows will increase and base flows will decrease, and (3) the annual pattern of synchronization between hydroperiod and water temperature will be altered. These alterations are expected to disturb floodplain plant communities, making them more vulnerable to establishment of invasive species. The primary objective of this study is to evaluate whether native and invasive riparian plant assemblages respond differently to alterations of climate and land use. To study the response of riparian wetlands to watershed and climate alterations, we utilized an existing natural experiment imbedded in gradients of temperature and hydrology-found among dammed and undammed rivers. We evaluated a suite of environmental variables related to water temperature, hydrology, watershed disturbance, and edaphic conditions to identify the strongest predictors of native and invasive species abundances. We found that native species abundance is strongly influenced by climate-driven variables such as temperature and hydrology, while invasive species abundance is more strongly influenced by site-specific factors such as land use and soil nutrient availability. The patterns of synchronization between plant phenology, annual hydrographs, and annual water temperature cycles may be key factors sustaining the viability of native riparian plant communities. Our results demonstrate the need to understand the interactions between climate, land use, and nutrient management in maintaining the species diversity of riparian plant communities. Future climate change is likely to result in diminished competitiveness of native plant species, while the competitiveness of invasive species will increase due to anthropogenic watershed disturbance and accelerated nutrient and sediment export.Item Open Access Conservation potential of barn owls (Tyto alba) in Pennsylvania(2010-04-30T20:12:23Z) Burtner, AliciaThough once prolific, the barn owl (Tyto alba) is now considered vulnerable in Pennsylvania and vulnerable-to-critically imperiled in all surrounding states. Barn owls are charismatic animals. They are wide-ranging generalists, so they are seldom the target of species-specific conservation efforts. Barn owls thrive in open habitats, so their North American extent expanded extensively in the early 1900 with the increased deforestation brought by intensified farming. Farming practices in the northern range of the Unites States subspecies (T. alba pratincola) are changing, and barn owl populations appear to be responding. Across Pennsylvania, open pastures are being replaced by smaller, row crop fields that have the decrease barn owl hunting habitat. With the exception of a several nesting box companies, few people are actively working towards conservation of barn owls. Statistically accurate descriptions of their specific habitat requirements are rare as a result of their wide range and general disinterest in studying the species. Radio-transmitted data from 16 barn owl fledglings released from Pittsburgh, Pennsylvania, was used to determine preferred habitat and climatic conditions. Owl dispersal paths spanned the eastern United States. Dispersal patterns consisted of bursts of rapid dispersal as well as heavy use of home ranges of 320 km2. The most heavily used point within each established home range used by a successful owl was compared to locations of mortalities using envelope, generalized linear, and classification and regression tree spatial models. The most heavily used habitat was low-lying, flat, and open with temperatures seldom dipping below freezing. The maps created by these models were compared using Pennsylvania as the focal region. The envelope model likely underestimated existing habitat due to its simplicity. Less than 5,000km2 of Pennsylvania was deemed habitat, an area that could support fewer than100 owls. The other models estimated that 50-60% of land cover both in Pennsylvania and across the eastern United States could be functional habitat. These estimates are likely more realistic for a generalist species like the barn owl. Given the breadth of the estimated habitat, populations should be more robust. It is more likely that a lack of nesting sites or a decline in prey numbers caused the present situation. Agricultural trends also favor increased pesticide use which would diminish prey populations as well as improved building conditions. This could remove potential nesting spots in the eaves of barns and silos. The acceptable temperature range does not extend into northern Pennsylvania, and nearing that range, survival necessitates increasingly sheltered nest sites, like buildings. A straightforward conservation approach would be placing artificial nesting boxes in areas of low pesticide use such as vineyards and organic farms.Item Open Access Determining Stream and Wetland Health in an Urban Restored Riparian Ecosystem in Durham NC through Benthic-macroinvertebrate Surveys(2014-04-24) Howington, JessieWater and aquatic habitat quality are frequently assessed by analyzing the structure of benthic macroinvertebrate communities in streams and other bodies of water. The Stream and Wetland Assessment Management Park (SWAMP) in Durham, NC, part of Sandy Creek, is a restored stream and wetland complex started in 2003. Restoration phases have been constructed to target both improvements in water quality and habitat. The two focal phases of restoration for this project were a re-sculpting of the geomorphology of the main stem of Sandy Creek and the creation of a braided or anabranched stream pattern. The anabranching stream pattern allows stream water to frequently come in contact with the soils in the floodplains for a prolonged period, promoting beneficial biogeochemical processes. This project tested both the change in water and habitat quality over time, as well as the difference in water and habitat quality between the restoration phases. Chemical and microbial laboratory analyses have shown that the water quality has improved since the restoration. Benthic macroinvertebrate data over an 8-year period demonstrate dissimilar results. The macroinvertebrate community analysis shows an overall decrease in both water and habitat quality since the restoration. There is also a significant difference in the macroinvertebrate communities found between restoration phases, specifically, the stream channel in the anabranching phase is shown to have lower water and habitat quality than that of the main stem. These findings are contrary to the expected results for a stream and wetland restoration project, but may be due to unusually high stream discharges in 2013 compared to earlier survey periods.Item Open Access Differential nutrient limitation of soil microbial biomass and metabolic quotients (qCO2): is there a biological stoichiometry of soil microbes?(PLoS One, 2013) Hartman, Wyatt H; Richardson, Curtis JBACKGROUND: Variation in microbial metabolism poses one of the greatest current uncertainties in models of global carbon cycling, and is particularly poorly understood in soils. Biological Stoichiometry theory describes biochemical mechanisms linking metabolic rates with variation in the elemental composition of cells and organisms, and has been widely observed in animals, plants, and plankton. However, this theory has not been widely tested in microbes, which are considered to have fixed ratios of major elements in soils. METHODOLOGY/ PRINCIPAL FINDINGS: To determine whether Biological Stoichiometry underlies patterns of soil microbial metabolism, we compiled published data on microbial biomass carbon (C), nitrogen (N), and phosphorus (P) pools in soils spanning the global range of climate, vegetation, and land use types. We compared element ratios in microbial biomass pools to the metabolic quotient qCO2 (respiration per unit biomass), where soil C mineralization was simultaneously measured in controlled incubations. Although microbial C, N, and P stoichiometry appeared to follow somewhat constrained allometric relationships at the global scale, we found significant variation in the C∶N∶P ratios of soil microbes across land use and habitat types, and size-dependent scaling of microbial C∶N and C∶P (but not N∶P) ratios. Microbial stoichiometry and metabolic quotients were also weakly correlated as suggested by Biological Stoichiometry theory. Importantly, we found that while soil microbial biomass appeared constrained by soil N availability, microbial metabolic rates (qCO2) were most strongly associated with inorganic P availability. CONCLUSIONS/ SIGNIFICANCE: Our findings appear consistent with the model of cellular metabolism described by Biological Stoichiometry theory, where biomass is limited by N needed to build proteins, but rates of protein synthesis are limited by the high P demands of ribosomes. Incorporation of these physiological processes may improve models of carbon cycling and understanding of the effects of nutrient availability on soil C turnover across terrestrial and wetland habitats.Item Open Access Drained coastal peatlands: A potential nitrogen source to marine ecosystems under prolonged drought and heavy storm events-A microcosm experiment.(Sci Total Environ, 2016-10-01) Wang, Hongjun; Richardson, Curtis J; Ho, Mengchi; Flanagan, NealOver the past several decades there has been a massive increase in coastal eutrophication, which is often caused by increased runoff input of nitrogen from landscape alterations. Peatlands, covering 3% of land area, have stored about 12-21% of global soil organic nitrogen (12-20Pg N) around rivers, lakes and coasts over millennia and are now often drained and farmed. Their huge nitrogen pools may be released by intensified climate driven hydrologic events-prolonged droughts followed by heavy storms-and later transported to marine ecosystems. In this study, we collected peat monoliths from drained, natural, and restored coastal peatlands in the Southeastern U.S., and conducted a microcosm experiment simulating coupled prolonged-drought and storm events to (1) test whether storms could trigger a pulse of nitrogen export from drought-stressed peatlands and (2) assess how differentially hydrologic managements through shifting plant communities affect nitrogen export by combining an experiment of nitrogen release from litter. During the drought phase, we observed a significant temporal variation in net nitrogen mineralization rate (NMR). NMR spiked in the third month and then decreased rapidly. This pattern indicates that drought duration significantly affects nitrogen mineralization in peat. NMR in the drained site reached up to 490±110kgha(-1)year(-1), about 5 times higher than in the restored site. After the 14-month drought phase, we simulated a heavy storm by bringing peat monoliths to saturation. In the discharge waters, concentrations of total dissolved nitrogen in the monoliths from the drained site (72.7±16.3mgL(-1)) was about ten times as high as from the restored site. Our results indicate that previously drained peatlands under prolonged drought are a potent source of nitrogen export. Moreover, drought-induced plant community shifts to herbaceous plants substantially raise nitrogen release with lasting effects by altering litter quality in peatlands.Item Open Access Ecological Assessment of the Flamingo Mangroves, Guanacaste, Costa Rica(2011-04-29) Fedak, Derek; Windstein, MarieMangroves are tropical and subtropical ecosystems found in intertidal zones that provide vital ecosystem services including sustenance of commercially important fishery species, improvement of coastal water quality through nutrient cycling and sediment interception, and protection of coastal communities from storm surge and erosion. However, land use conversion and water pollution are threatening these ecosystems and their associated services worldwide. This master’s project conducted an ecological assessment on a mangrove forest adjoining the property of the Flamingo Beach Resort and Spa in Playa Flamingo, located in the Guanacaste province of Costa Rica. The project analyzed vegetation health, water and soil quality, bird species richness, and identified threats to the forest. It also assessed several options for the resort’s development of ecotourism, such as community involvement, the construction of an educational boardwalk, and the creation of a vegetation buffer adjoining the mangroves. The results indicate that the Flamingo Mangroves are generally in a healthy state. Vegetation structure like canopy height, biomass, vegetation importance values, and species distribution compares well with previous ecological studies on mature tidal mangroves. The ecosystem supports 42 resident bird species and likely up to 30 migratory species. However, water quality is a major concern, which reported elevated levels of nitrogen and phosphorus through runoff and discharged wastewater in the northern section of the forest. Additionally, the western edge of the forest adjoining the beach road is frequently disturbed by automotive traffic and runoff, displaying reduced or stunted vegetation and sandy soil. This report contains several recommendations on how to preserve the mangroves by improving water quality, reducing physical and chemical disturbances, and engaging the community. The results of the project will be incorporated into our client‘s and Flamingo community‘s future management practices to conserve the Flamingo Mangroves and emphasize the value of this ecosystem.Item Open Access Ecological restoration of rich fens in Europe and North America: from trial and error to an evidence-based approach.(Biol Rev Camb Philos Soc, 2015-02) Lamers, Leon PM; Vile, Melanie A; Grootjans, Ab P; Acreman, Mike C; van Diggelen, Rudy; Evans, Martin G; Richardson, Curtis J; Rochefort, Line; Kooijman, Annemieke M; Roelofs, Jan GM; Smolders, Alfons JPFens represent a large array of ecosystem services, including the highest biodiversity found among wetlands, hydrological services, water purification and carbon sequestration. Land-use change and drainage has severely damaged or annihilated these services in many parts of North America and Europe; restoration plans are urgently needed at the landscape level. We review the major constraints on the restoration of rich fens and fen water bodies in agricultural areas in Europe and disturbed landscapes in North America: (i) habitat quality problems: drought, eutrophication, acidification, and toxicity, and (ii) recolonization problems: species pools, ecosystem fragmentation and connectivity, genetic variability, and invasive species; and here provide possible solutions. We discuss both positive and negative consequences of restoration measures, and their causes. The restoration of wetland ecosystem functioning and services has, for a long time, been based on a trial-and-error approach. By presenting research and practice on the restoration of rich fen ecosystems within agricultural areas, we demonstrate the importance of biogeochemical and ecological knowledge at different spatial scales for the management and restoration of biodiversity, water quality, carbon sequestration and other ecosystem services, especially in a changing climate. We define target processes that enable scientists, nature managers, water managers and policy makers to choose between different measures and to predict restoration prospects for different types of deteriorated fens and their starting conditions.Item Open Access Economic Viability of Blue Carbon Offsets in Coastal North Carolina & Louisiana(2013-04-26) Dong, Xiaoyun; Wang, Yifei; Moss, Leland; Kraft, NatalieCarbon offsets are becoming a necessary tool in carbon emission reduction. The offsets obtained through sequestration in coastal wetland vegetation and sediment is referred to as blue carbon. Our client, the Duke Carbon Offset Initiative (DCOI), is currently researching blue carbon to help meet Duke University’s goal of carbon neutrality by 2024. Through cost-benefit analyses and stakeholder collaboration a matrix was constructed to a) characterize the current state of blue carbon opportunities in North Carolina and Louisiana and b) guide DCOI’s development of a blue carbon decision. The unit cost of a blue carbon project in North Carolina is 170 times greater than the cost in Louisiana, mainly due to the lack of wetland restoration infrastructure in North Carolina. Environmental factors, such as land conversion and sea level rise, have a significant effect on the feasibility of the blue carbon projects. Although net wetland loss rate is low in North Carolina, the total converted wetland area is large. These areas are undesirable for blue carbon projects as they lack permanence. A risk analysis shows that in the Albemarle-Pamlico Peninsula, there are low elevation counties with a lower wetland replacement rate; these areas are more prudent choices for blue carbon project sites. In addition, an analysis of sea level rise impacts indicates that due to smaller critical tidal range, Louisiana has a higher carbon sequestration rate than North Carolina when sea level rises from 0.1-1 cm/year, not taking into account natural disturbances. Recommendations from this broad assessment of blue carbon include identifying potential sites for economical pilot studies and monitoring policy developments.Item Open Access Economic Viability of Blue Carbon Offsets in Coastal North Carolina & Louisiana(2013-04-26) Wang, Yifei; Dong, Xiaoyun; Kraft, Natalie; Moss, LelandCarbon offsets are becoming a necessary tool in carbon emission reduction. The offsets obtained through sequestration in coastal wetland vegetation and sediment is referred to as blue carbon. Our client, the Duke Carbon Offset Initiative (DCOI), is currently researching blue carbon to help meet Duke University’s goal of carbon neutrality by 2024. Through cost-‐benefit analyses and stakeholder collaboration a matrix was constructed to a) characterize the current state of blue carbon opportunities in North Carolina and Louisiana and b) guide DCOI’s development of a blue carbon decision. The unit cost of a blue carbon project in North Carolina is 170 times greater than the cost in Louisiana, mainly due to the lack of wetland restoration infrastructure in North Carolina. Environmental factors, such as land conversion and sea level rise, have a significant effect on the feasibility of the blue carbon projects. Although net wetland loss rate is low in North Carolina, the total converted wetland area is large. These areas are undesirable for blue carbon projects as they lack permanence. A risk analysis shows that in the Albemarle-‐Pamlico Peninsula, there are low elevation counties with a lower wetland replacement rate; these areas are more prudent choices for blue carbon project sites. In addition, an analysis of sea level rise impacts indicates that due to smaller critical tidal range, Louisiana has a higher carbon sequestration rate than North Carolina when sea level rises from 0.1-‐1 cm/year, not taking into account natural disturbances. Recommendations from this broad assessment of blue carbon include identifying potential sites for economical pilot studies and monitoring policy developments.Item Open Access Economic Viability of Blue Carbon Offsets in Coastal North Carolina & Louisiana(2013-04-26) Kraft, Natalie; Moss, Leland; Dong, Xiaoyun; Wang, YifeiCarbon offsets are becoming a necessary tool in carbon emission reduction. The offsets obtained through sequestration in coastal wetland vegetation and sediment is referred to as blue carbon. Our client, the Duke Carbon Offset Initiative (DCOI), is currently researching blue carbon to help meet Duke University’s goal of carbon neutrality by 2024. Through cost-benefit analyses and stakeholder collaboration a matrix was constructed to a) characterize the current state of blue carbon opportunities in North Carolina and Louisiana and b) guide DCOI’s development of a blue carbon decision. The unit cost of a blue carbon project in North Carolina is 170 times greater than the cost in Louisiana, mainly due to the lack of wetland restoration infrastructure in North Carolina. Environmental factors, such as land conversion and sea level rise, have a significant effect on the feasibility of the blue carbon projects. Although net wetland loss rate is low in North Carolina, the total converted wetland area is large. These areas are undesirable for blue carbon projects as they lack permanence. A risk analysis shows that in the Albemarle-Pamlico Peninsula, there are low elevation counties with a lower wetland replacement rate; these areas are more prudent choices for blue carbon project sites. In addition, an analysis of sea level rise impacts indicates that due to smaller critical tidal range, Louisiana has a higher carbon sequestration rate than North Carolina when sea level rises from 0.1-1 cm/year, not taking into account natural disturbances. Recommendations from this broad assessment of blue carbon include identifying potential sites for economical pilot studies and monitoring policy developments.Item Open Access Economic Viability of Blue Carbon Offsets in Coastal North Carolina & Louisiana(2013-04-26) Kraft, Natalie; Moss, Leland; Dong, Xiaoyun; Wang, YifeiCarbon offsets are becoming a necessary tool in carbon emission reduction. The offsets obtained through sequestration in coastal wetland vegetation and sediment is referred to as blue carbon. Our client, the Duke Carbon Offset Initiative (DCOI), is currently researching blue carbon to help meet Duke University’s goal of carbon neutrality by 2024. Through cost-benefit analyses and stakeholder collaboration a matrix was constructed to a) characterize the current state of blue carbon opportunities in North Carolina and Louisiana and b) guide DCOI’s development of a blue carbon decision. The unit cost of a blue carbon project in North Carolina is 170 times greater than the cost in Louisiana, mainly due to the lack of wetland restoration infrastructure in North Carolina. Environmental factors, such as land conversion and sea level rise, have a significant effect on the feasibility of the blue carbon projects. Although net wetland loss rate is low in North Carolina, the total converted wetland area is large. These areas are undesirable for blue carbon projects as they lack permanence. A risk analysis shows that in the Albemarle-Pamlico Peninsula, there are low elevation counties with a lower wetland replacement rate; these areas are more prudent choices for blue carbon project sites. In addition, an analysis of sea level rise impacts indicates that due to smaller critical tidal range, Louisiana has a higher carbon sequestration rate than North Carolina when sea level rises from 0.1-1 cm/year, not taking into account natural disturbances. Recommendations from this broad assessment of blue carbon include identifying potential sites for economical pilot studies and monitoring policy developments.Item Open Access Effects of Drawdown on Water Quality and Temperature in Duke University's Chiller Pond(2016-04-21) Giuliano, BrookeThe Duke Pond (or chiller pond) collects runoff from 20% of the Duke University campus and serves as a water source to the adjacent evaporative cooling plant. Due to frequent water withdrawals from the chiller plant, the water levels are expected to fluctuate anywhere from one to four feet daily (1.22 m). This project aims to (1) calculate a water budget for the pond, (2) determine the effects of fluctuating water levels on various water quality parameters, (3) assess whether the pond is compliant with state water quality standards, and (4) determine whether the stream temperature is significantly different at the inflow versus the outflow to the pond. An additional goal was to develop a GIS tool that estimates the annual sediment yield from the Duke pond’s watershed using the Universal Soil Loss Equation (USLE). After the pond stabilized I found that dissolved oxygen, pH, temperature, and specific conductance decrease with increasing water levels in the pond. The temperature is not significantly different at the outflow compared to the inflow stream. For the majority of the 8-month sampling period, dissolved oxygen and pH remain compliant with the state standards. Chlorophyll-a had one occurrence where it exceeded the standard. The USLE tool accurately delineates the watershed for the pond and calculates an annual sediment loss of 168.2 lb/ac/yr.Item Open Access Emerging contaminant or an old toxin in disguise? Silver nanoparticle impacts on ecosystems.(Environ Sci Technol, 2014-05-06) Colman, Benjamin P; Espinasse, Benjamin; Richardson, Curtis J; Matson, Cole W; Lowry, Gregory V; Hunt, Dana E; Wiesner, Mark R; Bernhardt, Emily SThe use of antimicrobial silver nanoparticles (AgNPs) in consumer-products is rising. Much of these AgNPs are expected to enter the wastewater stream, with up to 10% of that eventually released as effluent into aquatic ecosystems with unknown ecological consequences. We examined AgNP impacts on aquatic ecosystems by comparing the effects of two AgNP sizes (12 and 49 nm) to ionic silver (Ag(+); added as AgNO3), a historically problematic contaminant with known impacts. Using 19 wetland mesocosms, we added Ag to the 360 L aquatic compartment to reach 2.5 mg Ag L(-1). Silver treatments and two coating controls were done in triplicate, and compared to four replicate controls. All three silver treatments were toxic to aquatic plants, leading to a significant release of dissolved organic carbon and chloride following exposure. Simultaneously, dissolved methane concentrations increased forty-fold relative to controls in all three Ag treatments. Despite dramatic toxicity differences observed in lab studies for these three forms of Ag, our results show surprising convergence in the direction, magnitude, and duration of ecosystem-scale impacts for all Ag treatments. Our results suggest that all forms of Ag changed solute chemistry driving transformations of Ag which then altered Ag impacts.Item Open Access Evaluation of Pool Habitat Suitability of In-Stream Structures in Restored Streams of Western North Carolina(2007-08-31T19:47:10Z) Hammontree, AmyAbstract Evaluation of Pool Habitat Suitability of In-Stream Structures in Restored Streams of Western North Carolina by Amy Hammontree August 2007 One of the most critical aspects of stream restoration is the creation of suitable aquatic habitat. Much of this work is accomplished through the installation of both hard and soft in-stream structures. The structural stability of these practices has been well studied and monitored for decades. However, the evaluation of habitat potential of these structures has remained almost entirely qualitative and categorical. The objective of this study aimed to fill this void by quantitatively evaluating the habitat potential of a variety of common in-stream restoration structures and bend treatments in Western North Carolina through the measurement of common habitat features such as pool depth and length, distance to cover, and depth of cover (or undercut), with the ultimate goal of providing design recommendations for stream restoration projects listing habitat enhancement as a top priority. In analyzing the results of the study, high habitat quality was defined by large pool depths (for increased niche space and low flow velocities), small distances to cover, (for faster escape from predation), and large cover depth or undercut values, (for shelter, predation, and rearing). Collectively, soft structures provided the deepest pool depths, with shorter distances to cover and larger cover depth values than corresponding hard in-stream structures. Likewise, bend treatment groups containing soft in-stream structures also excelled in these areas. Bends containing hard structures produced much higher pool lengths, in many cases longer than the curvature of the bend itself. Design goals based on habitat enhancement of small streams should focus heavily on the installation of rootwad revetments and cover logs for creation of deeper pools with increased flow variation and increased cover depth. In addition, both these structures will also serve to promote the acquirement and continued recruitment of large and small woody debris into the streams. Where hardened structures are deemed necessary for structural or hydrologic purposes, they should be accompanied by soft in-stream structures to create combination bends to supplement habitat within these areas.
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