Department of Earth and Environmental Science
Undergraduate Research Abstracts
The Effect of Urbanization on Channel Morphology and Sediment Transport Patterns: Wissahickon Valley Watershed, Pennsylvania
The impact of urban sprawl in northwest Philadelphia PA has important implications for the natural systems and processes of the Wissahickon Valley Watershed. The Valley occupies the southern part of Fairmount Park, the oldest urban park in the United States, and has been a popular destination for decades. Recently, organizations within the Fairmount Park Partnership have acknowledged that Total Impervious Area (TIA) of the watershed now exceeds 30%, the consequence of urbanization and specific land-use changes. This condition has drastically compromised the health of the Watershed.
I studied the relationship between sediment-transport events and channel morphology within the Wissahickon Valley Watershed to learn more about current and future flooding risks. I hope to improve understanding of the effects of urbanization, current land-use policy, and current contractor plans on the geomorphologic and hydrologic patterns within the Watershed.
From June 2010 to March 2011, I mapped the longitudinal profile, channel geometry, and sediment grain-size distribution of the Cresheim Creek sub-Watershed. The results of my field work, coupled with 2010 precipitation data, show that a high TIA (24%) and relatively low soil permeability within the sub-Watershed have resulted in both sediment transport and flooding events that exceed what would normally be expected for a gravel-bedded stream in the Piedmont Province. In 2010, conservative results show that median grain size particles were transported 20 times, and bankfull height was exceeded six times. This information may help inform specific mitigation strategies to protect the Cresheim, and ultimately the Wissahickon Watershed, from the consequences of increase in TIA.
Modeling the Potential for Urban Agriculture in Philadelphia via Multispectral Analysis in GIS
In the context of growing concerns about the dependence of the international food system on fossil fuel and its vulnerability to soil degradation, climate change, and other diverse issues, a number of initiatives have arisen to develop and implement sustainable agricultural practices. Many of those seeking to reform the food system look to urban agriculture as a means to create localized, sustainable agricultural production, while simultaneously providing a locus for community building, encouraging better nutrition, and promoting the rebirth of depressed urban areas. The actual impact and feasibility of such a system, however, is not well understood, and many critics of urban agriculture regard its implementation as unrealistic and impractical.
Evidence from around the world suggests that, given the right economic conditions, urban agriculture can greatly increase food security of urban populations. Although the economic conditions that are conducive to urban agriculture, such as high food prices and low land values, do not exist in most developed nations, the continued growth of the world’s population, compounded by other issues such as rising energy costs, soil degradation, decline in fresh-water resources, and climate change represent a fundamental threat to long-term food security. Proponents of urban agriculture argue that, although they are not at risk of starvation, poor urban populations in the U.S. already suffer from food insecurity; nutrient-dense foods are expensive, while calorie-dense foods are cheap, economic conditions that have greatly increased the burden of obesity, heart disease, diabetes, and other diet-related diseases. Urban agriculture provides a means to combat these urban “food deserts,” while providing other services, such as re-tooling vacant land and increasing community involvement and solidarity, which have measurable impacts on urban life, such as reducing crime rates.
Considering high rates of urban unemployment and low land values in many decaying industrial centers in the US, there is a strong case to be made for the expansion of urban agriculture even without a true food crisis. In this project I used multispectral, high-resolution images to quantify Philadelphia’s capacity for urban agriculture to help city planners, entrepreneurs, community leaders, and citizens understand how urban agriculture can contribute to creating a sustainable food system in a major North American city. I classified multispectral images with a maximum-likelihood-algorithm in ArcGIS to generate baseline data on vegetative cover in Philadelphia. These data, in addition to mapping on the ground, were used to model land suitable for conversion to agriculture in Philadelphia. The results of my modeling showed that there is enough available land in Philadelphia to create an urban agriculture system that would make an appreciable contribution to the city’s food supply, but that implementation of such a system would have to address a number of major hurdles, including soil contamination and investment costs.
The Effect of Grazing on Benthic Aquatic Communities in Northern Mongolia
The herding of yaks, cows, sheep, and goats is the main source of income for many Mongolians, and has been for almost of all of Mongolia’s history. Recently, herding practices have changed, and there is less seasonal pasture rotation than in the past. Year-round grazing increases the impact of grazing on chosen pasture areas; that impact is not yet fully understood. Grazing in the riparian zones along rivers in northern Mongolia impacts benthic communities in those rivers. These impacts include siltation, erosion, increased nutrient loading, and changes in riparian vegetation.
To assess the effects of grazing on the aquatic ecology of the rivers, I sampled the benthic communities in two streams in Northern Mongolia. These streams were chosen because they represent two extremes of grazing. Turag Valley is subject to grazing by almost twice as many animals as the other river valley, Dalbay. I sampled benthic invertebrates using a Surber with a 500mm net in three habitats at three locations on each stream. The samples were sorted to family and then compared based on family richness and a diversity index, which compares the number of families and the number of individuals. I then compared the richness and diversity of the valleys, individual sites, and habitat types. My analysis shows no statistically significant difference between any of these communities, as the sample size is very small. However, the species richness is higher at all sites on Dalbay except at the midstream point, suggesting that the benthic aquatic communities on the less impacted stream are more robust. This suggestion is not statistically substantiated by the diversity index, so I cannot use this analysis to evaluate the impact of grazing on the benthic communities.
The Contamination of Lake Atitlan: Implications and Possible Solutions
Lake Atitlan, a beautiful endorheic lake in the highlands of southwestern Guatemala, is in severe danger, due to water contamination. The lake margin is home to over 200,000 people, 92% of whom who are indigenous Mayans who were persecuted during the Guatemalan civil war. Human communities surrounding the lake depend on it for their livelihood. The lake receives trash, sewage waters of all forms (aguas negras), and nutrient runoff from agriculture. There are almost no wastewater-treatment facilities around the lake; most homes depend on seepage pits for their sewage management.
Inputs of fecal coliform (E. coli) and other bacteria have rendered the lake water undrinkable. Recently, due to the influx of nutrients, there have been multiple cyanobacteria blooms as well. The lake water has been linked to several gastrointestinal illnesses. People are advised not to ingest it untreated. Poor families boil or chlorinate the water, while richer families buy bottles of water for their cooking and drinking needs.
I used journal entries from the Penn Guatemala Health Initiative database to determine how the contaminated lake affects people’s lives, and to learn their views regarding water in general. The nation of Guatemala has made the remediation of this endangered lake one of its top priorities, and has begun to dedicate money and resources to address the problem. Several NGOs are also working on in the problem of water quality in Lake Atitlan. The great volume of the lake makes chemical or mechanical solutions not feasible. One possible option is the construction of smaller, wastewater-treatment systems that utilize artificial wetlands. Public education in strategies of sustainable farming may help to minimize nutrient runoff, and proper disposal of raw sewage is necessary. Collaboration and communication is needed at all levels of this society to define a solution to this problem.
Protection of Public Water Resources in Beverly, MA
Over the last fifty years there have been many changes in the population density and settlement patterns of people in the United States. The ways in which human communities have developed have adversely affected the land and water quality. The increase in development and population in many areas has increased impervious surfaces and put a strain on outdated wastewater-treatment plants. During heavy rainfall this problem is exacerbated due to the added liquid these plants must process, resulting in thousands of gallons of sewage overflow. This overflow, coupled with stormwater runoff from the impervious surfaces, flows directly into streams, rivers, lakes, and the ocean. This untreated water contains many harmful bacteria, which pollute waterways, causing detrimental effects to both the ecosystem and humans. Every year public-health authorities close beaches to public use because of high bacterial counts. As development in these costal regions continues to grow, it is likely that the level of bacteria in the water will continue to rise.
Beverly, Massachusetts, is a case study for the effects of urbanization on marine water quality. In my study of this community I found no correlation between bacterial count in ocean water and urbanization, probably because improvements in sewage infrastructure and an overall increase in environmental awareness have compensated for increased population density and stormwater runoff. Communities will more effectively protect public waterways if study of land use and growing urbanization patterns leads to better stormwater management and diversion of future development to more strategic locations.
Response of Mongolian Plant Communities to Experimental Micro-Environments
Global climate change is now widely recognized as a process that will affect many of the ecosystems that support us. Some of the most extreme temperature variations that will result from climate change are predicted to occur in Mongolia, placing ecosystems there at high risk. The vulnerability of this area makes it particularly important to study the responses of its vegetation to environmental changes. Functional traits have become an important factor in the study of ecosystems, as there is increasing acceptance of the idea that they strongly affect ecosystem processes and therefore ecosystem services. The analysis of plant functional traits has become a useful tool for predicting vegetation responses to changing climate and, by proxy, the stability of the ecosystems they inhabit and the services they provide.
To study these questions we set up open-topped warming chambers (OTC) and control plots on the upper slope and lower slope of a valley in northern Mongolia. The OTC’s are plastic-sided chambers that are passively heated to increase the temperature within them by between 1.2 and 2 degrees Celsius. We also added additional water to half of the control and OTC plots on the upper slope. We assessed the relative abundance of each species in the community, and then we used those data to weight the importance of those species’ traits. From this we calculated a community weighted mean value for each plot, which we then compared between treatments. We expected to find shifts in trait values in response to the environmental changes we created. However, we found that on the community level, slope was the only significant factor. When we tested values from the upper slope exclusively, there was some effect of watering on trait values. We did not observe a significant effect from the open-topped warming chambers, indicating that, at least on the time scale of our experiment, the Mongolian steppe is resistant to the climate changes we administered.
Holocene Sea-Level Reconstruction from the Thames Estuary, United Kingdom
Sarah N. Fackler
The rate of global mean sea level rise that prevailed between 1993 and 2003 (~3.1 mm per year) is nearly two times that which was observed from 1961 to 2003 (~1.8 mm per year) (IPCC, 2007). Continuation of this trend will likely bring meters of eustatic (global sea level) change, major alterations to coastlines, and the inundation of low-lying areas (IPCC, 2007). Relative sea-level (RSL) change is the confluence of eustatic ocean-level variations, Glacial-Interglacial cycling, and isostatic adjustments (Edwards, 2007). Therefore, precise RSL reconstructions are critically needed to evaluate the models of Glacial Isostatic Adjustment (GIA) that are currently used to filter tide-gauge and satellite records (to resolve the climate warming component of sea-level rise), and to decipher rapid climate events (such as the 8.2 ka cooling event).
My study has begun to build such a sea-level database from the Thames Estuary, United Kingdom, at a higher paleoenvironmental resolution and analytical precision than previously achieved, by use of a transfer function. I constructed a detailed lithostratigraphy, using the Troels Smith method, for eight boreholes that penetrated a series of peat layers, drilled along the River Thames. I analyzed foraminiferal assemblages from two of these cores (Swanscome I and Tillbury), selected for their numerous basal peats (peat layers least susceptible to sediment compaction), and for their radiocarbon dates extending into the early Holocene. Characterized by an agglutinated assemblage in the vegetated marsh and a high diversity calcareous assemblage in the mudflats and sandflats and intertidal zone, the vertical zonation of foraminifera species, driven by tolerance to subaerial exposure, has previously been well defined within British salt-marshes (Horton and Edwards, 2006). As a result, I was able to relate the fossil counterparts from the Thames Estuary to these modern assemblages through a series of regressions, thereby reconstructing former paleo-marsh surface elevations. When I combined these new sea-level data with the lithostratigraphy and chronostratigraphy, I added seven freshwater limiting points and three index points from the early to mid-Holocene to the existing RLS reconstruction at defined error terms of ±0.1-0.3 m vertical resolution and annual to centennial age resolution.
I also used this new database to validate the RSL reconstruction method using d13C and C/N measurements, which enable marine sources to be distinguished from terrestrial sources, when combined with lithostratigraphy and chronostratigraphy as well. Both of the RSL reconstruction methods I used have the potential to link geophysical estimates with short-term instrumentation records, while furnishing precise and thorough records of relative sea-level change from intertidal environments on a global scale.
Using Stable Carbon Isotopes to Reconstruct Late-Holocene Sea-Level Change in Georgia, USA
Global sea-level rise is one of many threats resulting from current and future climate change; however, with most of the world’s population, including over half of Americans, living on or close to coasts, sea-level rise potentially has the most devastating and immediate consequences for humans. In order to mitigate and adapt to the future effects of rising sea levels, it is imperative to create a comprehensive model that can accurately predict future sea levels. While eustatic (ocean expansion due to melting ice sheets and warming surface temperatures) sea-level-rise measurements are important indicators of ocean-response capabilities, it is patterns in relative sea-level rise (the addition of isostatic compensation, or elevation changes) that will allow us to project rates of coastal erosion and degradation and predict which areas will be most affected.
Previous studies have mapped subsidence rates and consequently rates of relative sea-level rise along the East Coast of the United States from Maine to South Carolina. These studies have also demonstrated a spatial trend in the rate of 20th-century sea-level rise. Currently, there are no sea-level indices from Georgia or Florida to validate this trend for the entire East Coast.
My research project seeks to create sea-level index points for the coast of Georgia, using geologic data and δ13C analysis to compare these rates of relative sea-level rise to those previously determined. My research in Georgia will shed light on whether or not there is latitudinal variation in rates of relative sea-level rise, which could indicate thermal expansion of the ocean or reflect a response to mass losses from the Greenland ice sheet.
The Impact of Urban Greening on Tax Assessments in New Kensington, Philadelphia
Jason Landau Goodman
Many American cities continue to experience economic struggles from population loss and urban decentralization as a result of de-industrialization of the mid-19th century. As more residents and businesses moved away from urban areas, cities experienced a proliferation of vacant lots. To remedy this problem, urban greening programs have been developed as part of a social, economic, and environmental movement in cities across the United States to address urban decline, population sprawl, and the necessity for greenspace in cities.
In Philadelphia, the New Kensington section of North Philadelphia has become a prime example of how urban greening projects have positively impacted the local economy. After de-industrialization, this section of the city developed an extreme concentration of vacant lots, which led to extensive urban greening programs, sponsored by the New Kensington Community Development Corporation (NKCDC), to beautify the neighborhood. Recent studies have shown that urban greening directly increases property values.
My study addresses the extent to which tax assessments of properties adjacent to greened vacant lots have been affected in New Kensington diachronically. My data on the first major urban greening projects in New Kensington in 1997 show that greened vacant lots have had a direct and positive impact on tax assessments between 1990 and 2010. Using Geographic Information System (GIS) software, property data from NKCDC and PHS, and tax assessment data from the City of Philadelphia’s Office of Property Assessment, I show that properties adjacent to greened vacant lots in New Kensington in 1997 experienced an average increase from their 1990 tax assessment in 2010. My geospatial analysis, using buffer tools in GIS, supported the proximate principal with tax assessments across New Kensington. My study demonstrates that property owners have paid more taxes in geospatial relation to greened vacant lots over time in New Kensington.
Penn Park: Ecological Design in Response to Landscape Change and Policy Goals
Penn Park adapts the site of the “postal lands” for new uses through a design driven by historical land degradation and environmental-policy goals, and informed by ecological theory. To understand these drivers, I have: 1) traced the historical development and degradation of the lower west bank of the Schuylkill River using archival maps; 2) outlined national, regional, and local policy responses that seek to remediate land degradation and mitigate water issues; 3) reviewed the guiding concepts of art and ecology in landscape design theory; 4) presented a case study of Penn Park, describing its design features and evaluating how well the design of Penn Park responds to land-use history and policy; and 5) concluded with a reflection on sustainability as an organizing device for history, theory, policy, and design.
THE ASTRICLYPEIDAE: PHYLOGENETICS OF INDO-PACIFIC, SUPER-FLAT, HOLEY SAND DOLLARS
The Clypeasteroida is a group of about 250 extant species of sea urchins that includes the sand dollars (Scutellina). Among the scutelline sand dollars is a clade known as the Astriclypeidae, a group characterized by large, flat urchins that have holes, known as lunules, passing completely through the body. The type genus of the clade, Astriclypeus, has 5 lunules. However, two other genera in the group have two lunules: the fossil genus, Amphiope, and Echinodiscus, an extant genus found throughout the Indo-Pacific. These can be relatively large, very flat inhabitants of sandy beaches from South Africa north to the Red Sea, the northern Indian Ocean, and eastward to western Australia, Indonesia, Malaysia, the Philippines, and Japan. Despite their conspicuousness and relative abundance, they remain a poorly understood part of the macrobenthos. The genus currently houses four species (E. truncatus, E. tenuissimus, E. auritus, and E. bisperforatus). However, preliminary work with oral plate patterns and pedicellariae suggested that there are additional, cryptic taxa, providing impetus for a full revision of the genus using as many of the known specimens as possible. The original descriptions of E. auritus and E. bisperforatus (Leske, 1778) are both likely to encompass multiple species. In order to determine whether the currently recognized species should be further divided, we examined plate architecture, morphometrics, and pedicellariae. The morphological differences among the proposed species were consistent with their distribution patterns, which lent support to our decision as to which terminal taxa should be used to construct a phylogeny. Our analysis, based on the combination of morphological and biogeographic information, and relying on forms such as Astriclypeus as outgroups, allowed construction of a phylogenetic tree that included a total of nine terminal taxa within the genus Echinodiscus.
Effects of Available Nutrients on the Bioremediation of Louisiana Crude Oil from the BP Horizon Oil Spill
Kristina G. Koutsarova
I investigated the effects of available nutrients on the biodegradation of Louisiana crude oil by strains of Pseudomonas putida, Pseudomonas fluorescens, and Bacillus subtilis, using a solid-substrate fermentation (SSF) process for growing bacteria.
In the first part of the study I conducted bacterial plating experiments to determine the nutrient conditions under which a bacterial count higher than 3.00 x 109 CFU/g could be achieved for each strain grown on wheat bran as a substrate. I set the minimum requirements of 3.00 x 109 CFU/g to achieve a level of strain growth that would achieve the necessary biodegradation effect. My results indicated that all of the strains grew better with nutrient supplementation.
To test the effect of nutrient supplementation on the rate of biodegradation, I performed a series of shake-flask experiments on flasks containing both Louisiana crude oil and the bacteria grown under the conditions determined by the plating experiments.
My results indicated that the addition of nutrients in the beginning of the experiments and over time increases the rate of bioremediation. The presence of fertilizer increased the percentage of biodegradation for P. fluorescens type 1 from 51.34 % to 79.33%. Experiments with P. putida type 1 showed that the addition of fertilizer needs to be controlled: samples with fertilizer added every other day instead of every day increased the total hydrocarbon breakdown from 82.91% to 92.90%. I found that the amount of nutrients needed to optimize the rate of bioremediation should not be more than 10%. A 87.03% hydrocarbon degradation was achieved with 10% of fertilizer at a C:N:P ratio of 100:12:5, while the increase of fertilizer to 50% decreased the percentage of breakdown to 80.76%.
Reconstructing Relative Sea Level for Sea Breeze, New Jersey
Global climate change is an impending threat; its largest socio-economic impacts will likely be due to sea level rise. New Jersey, with its high annual revenues from tourism at its beaches, and its many multi-million-dollar properties located on the shoreline, is an area of concern for scientists and laymen alike. Sea-level reconstructions represent the best tool we have to predict future changes, as they aid modelers and scientists in understanding how sea level changes and at what rate.
My research has focused on identifying species of foraminifera in a sediment core from Sea Breeze, N.J. These microfossils, along with grain size and organic content of associate sediments, are indicative of specific ranges within the tidal zones, and allow us to deduce relative sea level for specific depths below modern sea level. These determinations, combined with radiocarbon dates of organic material, provide a series of sea-level index points. This allows me to compare my research to records constructed from other sites, creating a more complete record of recent changes in sea level for the Atlantic coast.
Atypical Growth Patterns in Proterozoic Carbonate Stromatolites: Analogs for Microbial Life on Mars?
The Proterozoic carbonate stromatolites of the Pahrump Group from the Crystal Spring formation of the Mojave Desert exhibit atypical growth patterns. These columnar stromatolites show repeated vertical growth sequences, each characterized by a layer of prolific growth followed by evidence of a geologic event represented by a dark layer with no stromatolites. Above the event layer is a recovery layer of normal sedimentary deposits with wavy laminae. The cycle repeats, with another layer of columnar stromatolite growth. To determine the cause of stromatolite dormancy or extinction, I collected representative random samples from each layer and analyzed them using Raman spectroscopy; thermo-gravimetric analysis (TGA); x-ray diffraction (XRD); x-ray fluorescence (XRF); scanning electron microscopy – electron dispersive spectroscopy (SEM-EDS); high-performance liquid chromatography (HPLC); and I analyzed the samples optically in thin section. I studied differences in the sections with stromatolites and without stromatolites with the objective of determining the change that occurred at the event layers. XRF and XRD results indicated high concentrations of feldspar-containing material and higher metal content at the event layers. The feldspar-containing material was probably originally volcanic ash that buried the stromatolites directly, or was carried by wind or water from surrounding areas. Higher levels of Ba, Zr, and Zn at the event layers further suggest a volcanic or hydrothermal origin of the event-layer material. These data help to provide a measure of stromatolitic sensitivity and can aid in understanding how stromatolite growth and morphology is affected by the surrounding environment. To my knowledge, sub-millimeter scale chemistry and structural analysis of these stromatolites has not been undertaken. My work, coupled with other stromatolite research, can advance the use of stromatolites as biosignatures in the search for microbial life on Mars.
The Effect of Potential Vorticity on Delta Channel Morphodynamics: Examining Elongating versus Bifurcating Behavior
Deltaic systems are constantly changing as channels avulse and evolve and new land is built around the delta. As much of the world's population lives on coastlines and deltas, it is important to understand the evolution of deltaic systems, as it affects the people inhabiting them. The Mississippi Delta, specifically, is currently losing more wetlands each year to sea level rise and subsidence, and it is important to find a way to attempt to build new land on the delta.
The dynamics of deltaic systems and their channels, however, are still not completely understood. It has been shown that delta-channel evolution is governed by both horizontal and vertical velocity profiles at the channel outlet, where a turbulent, narrow jet will form an elongate channel while a more diffuse, spreading jet will deposit mouth bars and create bifurcating channels that will build land.
My project shows that potential vorticity (PV), as developed by Falcini and Jerolmack (2010), is the key parameter that governs channel evolution and affects the depositional pattern of a river as it meets the ocean. A numerical analysis of data from previous experiments by Rowland et al. (2010) demonstrates that an elongated channel is created by a system with high PV. Furthermore, by varying the PV – a product of channel flow vorticity and suspended-sediment concentration gradient – in the laboratory, I developed both elongate channels and channel-mouth bar deposition to represent the different sedimentation patterns of a delta. My results provide experimental confirmation that flows with a high PV generate elongate channels, and that flows with a low PV form mouth-bar deposits and generate bifurcating channels.
Federal Policies for Promoting Large-Scale Offshore Wind Energy in the United States
Jessica Harvis Renny
Offshore wind is a domestic energy source that is poised to deliver renewable electricity to the New England and Mid-Atlantic regions and diversify the energy portfolio of the United States. Currently, however, no offshore wind farms exist in the US.
Major challenges exist for the US offshore-wind industry. First, offshore wind is extremely expensive to develop, and the cost of energy from offshore wind is significantly higher than conventional electricity prices. Second, the US permitting process in federal waters has been slow and uncertain, with up to twenty federal agencies involved and a nine-year time-frame for any offshore wind project to be awarded a lease. It is widely recognized that overcoming these two hurdles requires significant government action. In this thesis I have compiled data on US offshore-wind policy from academic, government, industry, consulting, and non-profit reports, and I introduce new information from seven interviews that I conducted with offshore-wind experts. I evaluate what the federal government has done, and what additional government action must be taken, to promote large-scale offshore wind-energy development in the US.
Offshore-wind policy has been constantly evolving, and several new government initiatives and policies have recently been adopted at the federal level. The best example is a new Department of the Interior initiative that proactively identifies areas that are well suited for offshore-wind development; this initiative may also shorten the permitting timeline to only five years. In addition, this year the Department of Energy identified research and development (R&D) needs that can drastically reduce the cost of offshore wind in the next twenty years. The nation’s first Ocean Policy and expanded renewable-energy tax credits have also been important signals to the industry in the past two years.
My analysis shows that the US is moving toward initial offshore wind-energy development, but ongoing government action will be necessary for fully harnessing this renewable energy resource. Large-scale offshore-wind development in the future will require greater interagency coordination in the federal permitting process, sustained federal funding for offshore-wind R&D, tax-credit extensions, and support for new infrastructure, including an offshore transmission backbone. These steps can reduce the risk that offshore-wind developers currently face, shorten the timeline for offshore-wind deployment, and make the cost of offshore-wind energy competitive with conventional energy sources.
Colony Collapse Disorder (CCD) in Honeybee Colonies in the USA
About one mouthful in three in our diet in the USA directly or indirectly benefits from honeybee pollination; honeybee pollination is responsible for $15 billion in added crop value. Since 2006, the USA has lost nearly one third of all honeybee colonies due to an unclear phenomenon termed “colony collapse disorder” (CCD). Some scientists argue that CCD is caused by a single factor, while others state that it is the combination of different factors that causes bee colonies to collapse. These factors include pesticide exposure, invasive parasitic mites, new immune-targeting diseases, and stresses from beekeeping practices. While the causes of CCD are still being studied, it is clear that commercial beekeepers in the USA must change their beekeeping procedures. Furthermore, reports suggest that the organic beekeeping movement has suffered almost no beehive losses caused by CCD.
The Combined Impact of Rising Temperature and Grazing Density on Plant Communities in Northern Mongolia
It is now widely acknowledged that biodiversity and other plant properties in terrestrial ecosystems will be affected by land-use changes and climate change in the next century. Available evidence suggests that climate change and grazing could affect plant phenology and flower production, although this complex reaction is difficult to predict. Even less is understood about the interaction between grazing and temperature on plant properties.
Available climate models predict that Northern Mongolia will experience accelerated warming in the next century. During the summer of 2010 I undertook a study in Northern Mongolia to determine the individual and combined effects of warming and grazing density on the phenology and flower production of indigenous plant species. I divided experimental blocks into plots a) protected from and b) not protected from grazing; each of these plots contained both an open-top-chamber sub-plot and a control sub-plot. I counted the number of flowers of every species in each plot once a week. I analyzed common species to determine whether warming, grazing, and a combination of the two factors influenced the total number of flowers vs. presence of the species, as well as the median date of flowering. My results demonstrated that warming significantly decreased the number of flowers in five of the 17 species tested, and that grazing significantly decreased the number of flowers in two of the 17 species tested. Only Artemisia commutate and Sibbaldiante adpressa appeared to be significantly affected by the additive processes of treatment and grazing. The only species that exhibited a significant change in median flower date was Koeleria macrantha, which experienced an earlier median flower date in grazed areas. These results show that reproductive ecology can be affected by climate and land-use change; however, due to the complexities of a terrestrial community, this response cannot be generalized to all species or biomes, as some species may be more affected by these factors than others.
From Human Exercise to Renewable Energy
With fossil-fuel resources dwindling and prices of energy rising, the need for more sustainable/renewable energy sources is pressing. Renewable energy sources are constant. Humans get metabolic energy from the food they consume; they convert some of that energy into work. Renewable energy can be harvested from this process.
Human production of kinetic energy can be channeled into mechanical energy, which can be converted to electric energy. This can be achieved by exercising. Humans doing work, exercising, on a bike or other machine, have turned their kinetic energy into mechanical energy. An electric generator converts this mechanical energy into electricity. Exercise machines need an electric controller to regulate this flow of electricity. A human exercising cannot always produce a constant level of output, as the intensity of effort can rise and fall instantaneously. The electric controller prevents damage from a surge in the current that may result from an increase in pedaling rate. The controller will quickly recalculate to the new input and increase the electrical output after resetting at zero. This electricity can be utilized for charging a battery (thus storing energy), or the electricity can be used immediately. The amount of electricity produced is directly related to the duration of the exercise, and the resistance level of the machine. Multiple machines, for a longer duration, with a high resistance will result in larger levels of renewable electric energy. The average human can produce a constant output of 150 watts for the duration of a workout. This can be doubled briefly during a peak effort.
Electric Vehicles as an Integrated System of Networked Energy Storage
Will Van Eaton
Electric vehicles (EVs) are on track to replace the vehicles driven by internal-combustion engines. EVs have many clear advantages, including zero direct emissions, which make them a desirable alternative. Other, less clear advantages include providing a source of energy storage during off-peak hours. This is suitable for alternative and renewable sources of energy that do not operate on a cycle that revolves around the 9:00 to 5:00 work day, such as wind power and geothermal power. Another advantage, further developed in my thesis, is the concept of load shifting and peak shaving.
A collection of EVs that operate as a form of networked energy storage is able to level out demand of electricity by charging at night and/or during off-peak hours, and then discharging energy back into the power grid during peak hours. Reducing peak demand can also mitigate the need for “peaker plants,” which are frequently the most expensive, and sometimes the most polluting, types of power plants to operate.
When this vehicle-to-grid (V2G) system is applied to the local University of Pennsylvania campus, the previously listed advantages exist in addition to the potential for cost and energy reductions for the University. Assuming that, in 2020, EVs with technical specifications similar to those of the Tesla S signature edition are more standard, then the average EV battery pack could have a capacity of 85 kWh and a range of 300 miles.
By charging the EVs when electricity prices are lowest, and discharging them when the prices are highest, the EV owner and the University could take advantage of the energy arbitrage and reduce overall costs. The University, depending on the amount of time an individual vehicle is parked, could save between $140.00 and $240.00 per vehicle per year, while the EV owner could save between $85.00 and $100.00 per vehicle per year. Assuming a cost of $2,000.00 for each charging station, and a conservative, weighted average savings of $165.00, the University could break even in ~12 years, which is well within the 25-year expected lifetime of the charging station.
When expanded to a parking garage of 800 vehicles, with 25 percent of the vehicles parked fully from 9:00 AM to 5:00 PM, and 75 percent of the vehicles only parked during peak parking hours of 11:00 AM to 2:00 PM, annual savings for the University could reach $140,000.00. With 4,000 vehicles, and the same parking behavior, the University could expect to save as much as $675,000.00 per year.
This level of reduction in energy cost is probably not sufficient in itself to spur the adoption of EVs at the university of Pennsylvania; however the projected savings can act as an incentive for the University to put in place the support infrastructure that the EVs will require in the future.
The Geochemistry of Limestone Cave Waters: Implications for the Development of New Methods for Studying Paleoclimate
The chemistry of limestone cave waters tells an interesting and complicated story about the flow paths of water underground. The composition of cave water depends on interactions with soil air, cave air, and the rocks through which the water passes. The composition of cave water also depends on the kinetics of those interactions, which can vary due to factors like whether the water is still or flowing, the amount of water that is flowing at a given time, and the circulation patterns of the air in the cave.
To explore the chemistry of limestone cave waters, I collected water samples and conducted on-site measurements at Indian Echo Caverns, a commercial cave in Hummelstown, Pennsylvania, developed in Ordovician rocks. I measured the temperature and partial pressure of carbon dioxide of the cave air at different locations in the cave, and the temperature and pH of water in lakes, a stream, and water dripping from various speleothems. I performed laboratory titrations to determine the carbonate species present in water samples I collected; I used an Inductively Coupled Plasma instrument to find the concentrations of calcium and magnesium; and I analyzed samples using an Isotopic Ratio Mass Spectrometer to determine 13C/12C ratios.
By comparing my data with reports of studies undertaken on larger scales at different caves, I developed a model of how the cave water in Indian Echo Caverns interacts with its surroundings. I also considered how that model might be used to develop a method for reconstructing paleoclimate using fluid inclusions in speleothems.
Effects of Heavy Metals on Soil Microbial Activity in Palmerton, Pennsylvania
Heavy metals are present in high levels in soils downwind of two zinc smelters in Palmerton, Pennsylvania. When the smelters were taken out of production in 1980, levels of Zn, Cd, Pb, and Mn were high enough in the soils that plant communities were unable to regenerate themselves naturally. Without the organic input from plants, microbial activity was dramatically compromised, leaving the soil in a poor state. A short-term, small-scale reclamation effort is currently under way, in an attempt to determine a potential time scale for reclaiming the soil. The goal of the reclamation is to remediate the soil by eliminating as much of the metals as possible, while restoring plants to the area, promoting more microbial activity. Once the cycle involving organic matter and microbes is restored, the site should continue to develop toward better quality soil.
I collected eighteen soil samples — six each from a non-replanted Baseline site, a 2003 replanted site, and a 2006 replanted site. I measured the total and easily extractable, or plant available, Zn, Pb, Cd, and Mn contents of each sample through XRF analysis and neutral-salt extraction, which showed that the sites replanted in 2003 contained the highest levels of contamination, but the lowest concentrations of mobile heavy metals, as determined by the ratio between plant-available metals and total metals. The 6 samples from the site replanted in 2003 also yielded the highest C and N percentages. I measured the CO2-accumulation and respiration rates of the 18 samples, showing that the 2003 samples had accumulated the most CO2 and also yielded the highest respiration rates. Based on this short-term soil chronosequence, there does not seem to be a quick solution to achieving better soil quality in Palmerton, PA. However, the survival of the grasses over the seven-year period on the 2003 plot and over the four-year period on the 2006 plot suggests that a longer and larger-scale reclamation effort is possible, and may yield more success. Large-scale replanting may at least contribute enough organic matter to the system to allow the microbial activity to increase, which would indicate that the soils were returning to a better quality.
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