Nutrient Loads in an Urban Ozark Watershed: Jordan, Fassnight and Upper Wilson\u27s Creeks, Springfield, Missouri

The study watershed includes Jordan Creek, the primary stream draining the central downtown area of Springfield, Missouri, and also Fassnight and upper Wilson Creeks. Ten sample sites were established within the watershed and water samples and were collected during baseflow and storm runoff events between August 1, 2004 and July 31, 2005. Samples were tested for total nitrogen (TN), total phosphorus (TP) and selected heavy metals (zinc, arsenic, lead, copper and cadmium) and the parameters pH, specific conductance, turbidity, temperature and dissolved oxygen. Rating curves were used to correlate discharge and water quality variables. Separate rating curves were developed for baseflow and storm runoff conditions. A significant negative correlation between baseflow TN and water temperature indicated that variation in TN could be due to seasonal trends in plant activity. A negative correlation between TP and specific conductivity is probably due to increased TP with storm runoff. Concentrations of TP and TN at the study watershed outlet were found to be below proposed MoDNR TMDL limits for 86 % and 55 % of the study period respectively. Nutrient levels in Jordan Creek are similar to those of Ozark watersheds not influenced by waste-water treatment plants. Annual loads from the study watershed based on daily average flow are estimated to be 26.8 and 2.2 metric tons/year for TN and TP respectively. Concentrations of TN are relatively similar among sample sites at storm runoff, and baseflow variations appear to be related to karst spring discharge. Concentrations of TP are also similar among sites at baseflow but storm levels can be affected by land use and channel condition

Reevaluation of Wolfcampian Cyclothems in Northeastern Kansas: Significance of Subaerial Exposure and Flooding Surfaces

Ten cyclothems from the Wolfcampian of northeastern Kansas, including parts of the Council Grove and Chase Groups, were examined in detail with particular attention to discontinuity surfaces and paleosol development. These cyclothems are shown to be bounded by major discontinuities, or sequence boundaries, where marine limestones abruptly overlie paleosol profiles. Occurring within these cyclothemic sequences are prominent meter-scale cycles that are bounded by flooding surfaces, many of which overlie facies exhibiting evidence of subaerial exposure. They are developed within both the marine carbonate and shale intervals and variegated mudstone intervals of the cyclothems. These meter-scale cycles show a consistent carbonate-to-clastic pattern regardless of their stratigraphic position or component facies. Climate fluctuations within a generally monsoonal environment are determined to be the most likely forcing mechanism for the meter-scale cycles, with wetter climate phases resulting in the increased influx of terrigenous clastic sediment and drier climate phases favoring carbonate precipitation. Evidence of climate change at the scale of the cyclothemic sequences is also recognized in the studied interval. Cycles at both scales indicate that relative sea-level rise was associated with increasingly arid conditions and that sea-level fall was associated with an intensification of seasonal rainfall

Hydrogeophysics of gravel-dominated alluvial floodplains in eastern Oklahoma

Scope and Method of Study: Geophysical and hydraulic surveys of three floodplains in eastern Oklahoma with the purpose of estimating floodplain heterogeneity and identifying high-flow domains or preferential flow paths.Multi-electrode surface electrical resistivity (ERI) profiles of the floodplains show lenticular features with high resistivity within a domain of lower resistivity. Floodplain subsoil is composed of mixture of coarse and fine fractions (less than 0.25 mm). The proportion of the fine fraction from cores at the sites shows a negative power relationship with both resistivity (R 2 = 0.85) and hydraulic conductivity (R 2 = 0.72), suggesting that the fine content is the major factor in the hydraulic and electrical behavior of the gravel subsoil. A linear relationship between hydraulic conductivity and resistivity is significant and the resulting equation K sat = 0.11ρ; allows resistivity (ρ) to be interpreted as saturated hydraulic conductivity ( K sat ). The median hydraulic conductivity on all profiles from all sites was at least 20 m d -1 , which is within the range for gravel soils. This high hydraulic conductivity suggests that at least half of the subsurface at each floodplain is likely to behave as a "high-flow domain" with the ability to conduct water at rates of 20 m d -1 or greater. Several ERI profiles at Barren Fork Creek (BFC) had high resistivity values that were significantly higher than the remaining ERI profiles at BFC and the other sites measured at the 84 th percentile. Those ERI profiles were obtained from an area within the BFC study site where a trench injection test found a tracer (Rhodamine WT) to move in a manner that suggests preferential flow. A storm runoff pulse passed the BFC site over May 1-5, 2009 featuring 2.2 m of stage increase, which caused the water table to rise into the gravel-dominated vadose zone at the site. Water table maps, corresponding to the times when stream elevation matched the selected hydraulic conductivity elevations, were prepared from pressure transducers placed in monitoring wells at the site. It appeared that there was little attenuation of the energy of the storm pulse even at the furthest point in the study site: at 180 m from the stream the flood peak had only dropped 0.25 m and was delayed by 1.5 hours, suggesting that the floodplain was a "high-flow domain". Comparisons between depth slices of hydraulic conductivity, created by interpolating the ERI profiles, and the water table maps showed that areas of highest resistivity coincided with areas of relatively low water table slope and vice versa. Since high hydraulic conductivity implies less resistance to flow (and less loss of energy over distance), this is the response one would expect to see. Therefore, despite the floodplain as a whole constituting a high-flow domain, areas of preferential flow exist within the floodplain, characterized by highs in both hydraulic conductivity and resistivity

Talking Politics on Facebook: Network Centrality and Political Discussion Practices in Social Media

This study examines the relationship between political discussion on Facebook and social network location. It uses a survey name generator to map friendship ties between students at a university and to calculate their centralities in that network. Social connectedness in the university network positively predicts more frequent political discussion on Facebook. But in political discussions, better connected individuals do not capitalize equally on the potential influence that stems from their more central network locations. Popular individuals who have more direct connections to other network members discuss politics more often but in politically safer interactions that minimize social risk, preferring more engaged discussion with like-minded others and editing their privacy settings to guard their political disclosures. Gatekeepers who facilitate connections between more pairs of otherwise disconnected network members also discuss politics more frequently, but are more likely to engage in risk-tolerant discussion practices such as posting political updates or attempting political persuasion. These novel findings on social connectedness extend research on offline political discussion into the social media sphere, and suggest that as social network research proliferates, analysts should consider how various types of network location shape political behavior

Online Learning in Schools of Business: The Impact of Strategy on Course Enrollments

Online education in schools of business is an ongoing, emerging practice. Strategic planning by institutions and programs seeks to identify the most relevant factors in providing the most effective online learning for students. This requires that schools of business figure out what factors positively and directly affect course enrollments. This research study surveyed deans of AACSB-accredited business schools to determine their online learning strategies and practices. The results of the survey and study support online education as a means to meet the increasing needs of a diverse and ever-changing student population both now and in the future

Field evidence of a natural capillary barrier in a gravel alluvial aquifer

Ozark streams commonly feature “composite” floodplains, in which the vadose zone consists of silt or silt loam soils (?1 m thick) overlying gravel subsoil. Previous work has shown that preferential flow paths can exist within the gravel subsoil, which can conduct water and P at rates exceeding the sorption capacity of the gravel. At a site on Barren Fork Creek, a 1- by 1-m infiltration plot was constructed and an infiltration experiment was performed using sequentially introduced solutes including P (the constituent of regulatory interest), Rhodamine-WT (Rh-WT, a visual tracer), and Cl− (an electrical tracer). The solute transport was measured with monitoring wells (MWs) placed 1 m from the plot boundary and 5 m down the groundwater flow gradient using an electrical resistivity imaging (ERI) array. The ERI method utilized differences between a pre-infiltration background image and subsequent temporal images taken during the test to quantify changes induced by the tracers. The infiltration test maintained a steady-state flow rate of 4.5 L min−1 for 84.75 h. Electrical resistivity imaging data showed significant changes in resistivity induced by the tracers within the soil vadose zone under the plot but no similar changes within the gravel, indicating that the interface was acting as a capillary barrier. Electrical resistivity images 5 m away from the plot showed tracer breakthrough into the gravel in areas not sampled by the MWs. Solute detection was limited in MWs, indicating that MWs could not adequately monitor movement below the capillary barrier because it controlled migration of solute to the heterogeneous phreatic zone

Integrated Network Architecture for NASA's Orion Missions

NASA is planning a series of short and long duration human and robotic missions to explore the Moon and then Mars. The series of missions will begin with a new crew exploration vehicle (called Orion) that will initially provide crew exchange and cargo supply support to the International Space Station (ISS) and then become a human conveyance for travel to the Moon. The Orion vehicle will be mounted atop the Ares I launch vehicle for a series of pre-launch tests and then launched and inserted into low Earth orbit (LEO) for crew exchange missions to the ISS. The Orion and Ares I comprise the initial vehicles in the Constellation system of systems that later includes Ares V, Earth departure stage, lunar lander, and other lunar surface systems for the lunar exploration missions. These key systems will enable the lunar surface exploration missions to be initiated in 2018. The complexity of the Constellation system of systems and missions will require a communication and navigation infrastructure to provide low and high rate forward and return communication services, tracking services, and ground network services. The infrastructure must provide robust, reliable, safe, sustainable, and autonomous operations at minimum cost while maximizing the exploration capabilities and science return. The infrastructure will be based on a network of networks architecture that will integrate NASA legacy communication, modified elements, and navigation systems. New networks will be added to extend communication, navigation, and timing services for the Moon missions. Internet protocol (IP) and network management systems within the networks will enable interoperability throughout the Constellation system of systems. An integrated network architecture has developed based on the emerging Constellation requirements for Orion missions. The architecture, as presented in this paper, addresses the early Orion missions to the ISS with communication, navigation, and network services over five phases of a mission: pre-launch, launch from T0 to T+6.5 min, launch from T+6.5 min to 12 min, in LEO for rendezvous and docking with ISS, and return to Earth. The network of networks that supports the mission during each of these phases and the concepts of operations during those phases are developed as a high level operational concepts graphic called OV-1, an architecture diagram type described in the Department of Defense Architecture Framework (DoDAF). Additional operational views on organizational relationships (OV-4), operational activities (OV-5), and operational node connectivity (OV-2) are also discussed. The system interfaces view (SV-1) that provides the communication and navigation services to Orion is also included and described. The challenges of architecting integrated network architecture for the NASA Orion missions are highlighted

Flow and transport experiments for a streambank seep originating from a preferential flow pathway

Streambank seeps commonly originate from localized heterogeneity or preferential flow pathways (PFPs) in riparian floodplains. However, limited field data have been reported on ground water seep flows and solute transport to seeps from PFPs. The objective of this research was to build upon previous floodplain-scale investigations of PFPs by analyzing seep discharge and transport characteristics through a single PFP. An important research question was whether this PFP could be conceptualized as a homogeneous, one-dimensional flow path. Streambank seep discharge measurements were obtained by inducing a hydraulic head in a trench injection system. Also, co-injection of Rhodamine WT (RhWT) and a potassium chloride (KCl) tracer over a 60-min period was used to investigate transport dynamics. Seep discharge and breakthrough curves for electrical conductivity (EC) and RhWT were measured at the streambank using a lateral flow collection device. The breakthrough curves were fit to one-dimensional convective-dispersion equations (CDEs) to inversely estimate solute transport parameters. The PFP from which the seep originated was clean, coarse gravel (6% by mass less than 2.0 mm) surrounded by gravel with finer particles (20% by mass less than 2.0 mm). Located approximately 2 m from the trench, the seep (50 cm by 10 cm area) required at least 40 cm of hydraulic head for flow to emerge at the streambank. At a higher hydraulic head of 125 cm, seep discharge peaked at 3.5 L/min. This research verified that localized PFPs can result in the rapid transport of water (hydraulic conductivity on the order of 400 m/d) and solutes once reaching a sufficient near-bank hydraulic head. A one-dimensional equilibrium CDE was capable of simulating the EC (R2 = 0.94) and RhWT (R2 = 0.91) breakthrough curves with minimal RhWT sorption (distribution coefficient, Kd, equal to 0.1 cm3/g). Therefore, the PFP could be conceptualized as a one-dimensional, homogenous flow and transport pathway. These results are consistent with previous research observing larger-scale phosphorus transport

Ariel - Volume 4 Number 5

Editors David A. Jacoby Eugenia Miller Tom Williams Associate Editors Paul Bialas Terry Burt Michael Leo Gail Tenikat Editor Emeritus and Business Manager Richard J. Bonnano Movie Editor Robert Breckenridge Staff Richard. Blutstein Mary F. Buechler Alice M. Johnson J.D. Kanofskv Rocky Webe

The hydraulic conductivity structure of gravel-dominated vadose zones within alluvial floodplains

The floodplains of many gravel-bed streams have a general stratigraphy that consists of a layer of topsoil covering gravel-dominated subsoil. Previous research has demonstrated that this stratigraphy can facilitate preferential groundwater flow through focused linear features, such as paleochannels, or gravelly regions within the vadose zone. These areas within the floodplain vadose zone may provide a route for interactions between the floodplain surface and alluvial groundwater, effectively extending the hyporheic zone across the floodplain during high stream stage. The objective of this research was to assess the structure and scale of texture heterogeneity within the vadose zone within the gravel subsoils of alluvial floodplains using resistivity data combined with hydraulic testing and sediment sampling of the vadose zone. Point-scale and broad-scale methodologies in combination can help us understand spatial heterogeneity in hydraulic conductivity without the need for a large number of invasive hydraulic tests. The evaluated sites in the Ozark region of the United States were selected due to previous investigations indicating that significant high conductivity flow zones existed in a matrix which include almost no clay content. Data indicated that resistivity corresponded with the fine content in the vadose zone and subsequently corresponds to the saturated hydraulic conductivity. Statistical analysis of resistivity data, and supported by data from the soil sampling and permeameter hydraulic testing, identified isolated high flow regions and zones that can be characterized as broad-scale high hydraulic conductivity features with potentially significant consequences for the migration of water and solutes and therefore are of biogeochemical and ecological significance