1,456 research outputs found

    Stream Water Quality to Support HUC 12 Prioritization in the Lake Wister Watershed, Oklahoma: August 2017 through May 2019

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    Nonpoint source pollution associated with human land use (agriculture and urbanization) is one of the leading causes of impairment to waterways in the United States (EPA 2000). The primary pollutants associated with agricultural and urban land use are sediment and nutrients which enter nearby streams during rain events and are then carried downstream. These sediments and nutrients may result in water quality issues in the downstream water bodies like increased algal growth or decreased water clarity (e.g. Smith et al., 1999). Best management practices (BMPs) are often used to mitigate the effects of nonpoint source pollution in the watershed. Practices such as riparian buffers installed along the edge of field and conservation tillage (e.g., no-till, spring-till, and cover crops) slow overland flow, reducing erosion and nutrient loss from the landscape (Schoumans et al. 2014). Installing BMPs throughout the entire watershed would have the greatest effect at reducing nonpoint source pollution; however, this is not socially or economically feasible. Targeting critical source areas or priority watersheds for BMPs installation, optimizes the benefits while reducing the overall (Sharpley et al. 2000)

    Watershed Investigative Support to the Poteau Valley Improvement Authority: Stream Water Quality to Support HUC 12 Prioritization in the Lake Wister Watershed, Oklahoma

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    Nonpoint source pollution associated with human land use (agriculture and urbanization) is one of the leading causes of impairment to waterways in the United States (EPA, 2000). The primary pollutants associated with agricultural and urban land use are sediment and nutrients which enter nearby streams during rain events and are then carried downstream. These sediments and nutrients may result in water quality issues in the downstream water bodies like increased algal growth or decreased water clarity (e.g. Smith et al., 1999)

    Bioassessment of Four Karst Springs at Hobbs State Park – Conservation Area with a Focus on Diving Beetle (Dytiscidae: Hydroporinae) Species of Concern

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    Four springs were surveyed at Hobbs State Park-Conservation Area to provide an initial bioassessment and to determine occurrences of two endemic predaceous diving beetles of concern, Heterosternuta sulphuria and Sanfilippodytes sp. Habitat in the four spring runs were dominated by bedrock and gravel substrate with heavy accumulations of leaf litter. Thirty-three taxa representing 11 orders were collected from the four springs. Non-insect taxa included Oligochaeta, Physidae, and Isopoda, and predominant insect orders included Ephemeroptera, Coleoptera, Diptera, and Trichoptera. The total number of taxa across springs ranged from seven to 19, with total abundances ranging from 39 to 86 individuals. No individual taxon occurred across all four springs. Percent tolerant organisms and the Hilsenhoff Biotic Index showed that spring communities were dominated by taxa tolerant to organic pollution, likely because of low flows and heavy accumulations of leaves. Predators were the dominant functional group followed by shredders. The endemic, predaceous diving beetle Heterosternuta sulphuria was collected from two springs and Sanfilippodytes sp. was collected from three springs. One spring contained the largest number of Sanfilippodytes sp. individuals recorded among all other aquatic habitats surveyed to date. Findings highlight the importance of spring systems at Hobbs State Park Conservation Area for endemic-species conservation, while information on the invertebrate community provides a baseline for future monitoring and comparison

    Assessment of total organic carbon concentrations in two streams of Northwest Arkansas: Town Branch and Brush Creek

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    Within a stream, changes in flow rate and local environment can affect the total organic content (TOC) concentrations in the stream water and TOC delivery downstream to water supply reservoirs. Disinfection by-products (DBPs) result from various chemical reactions between chlorine, bromine, and organic carbon in raw water during the drinking water treatment process; DBPs are potential carcinogens and are regulated by the U.S. Environmental Protection Agency. In this project, we measured the TOC concentrations in two streams in the Beaver Lake Watershed: Town Branch and Brush Creek. We then compared TOC concentrations between the two streams and to that observed in streams draining in forested areas to determine if differences in mean concentrations might be related to the streams’ catchment. Finally, using instantaneous discharge at the time of sampling, we determined if TOC concentrations were significantly correlated to the volumetric flow of a stream. The data suggest that there is a positive linear relationship between the TOC concentration and the flow rate of a stream. While TOC concentrations did not vary between sites, TOC flux and yield were significantly different between the two streams

    Relationship Between Land-Use and Water Quality in Spring-Fed Streams of the Ozark National Forest

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    Spring-fed streams are abundant in karst topographic regions such as the Ozarks, providing an important and valuable water resource. Many of these spring-fed streams presently receive agriculture runoff, but few studies have examined the impacts of this runoff on water quality. We examined water quality in Ozark spring-fed streams surrounded by either agricultural (N=3) or primarily forested land (N=3) in the riparian zone. We hypothesized that agricultural sites would have greater dissolved nutrient concentrations and conductivity than forested sites and that water quality would fluctuate with distance from the spring source. Conductivity (

    Reducing water extractable phosphorus in poultry litter using chitosan treatment

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    Phosphorus (P) is an important factor in the eutrophication of freshwater, and watershed sources include effluent discharges and the landscape. Poultry litter applied to the landscape can be a potential source of P, which is dependent on rainfall, runoff and dissolution. Chitosan, the deacetylated form of the biopolymer chitin, has been shown to have an effect on reducing water extractable phosphorus (WEP) in poultry litter when applied as a powder. The intent of this study was to measure the effect that poultry litter treatment (PLT), acetic acid and incubation time have on chitosan’s ability to reduce WEP in poultry litter. The results were that (1) the presence of PLT in the litter inhibits chitosan’s ability to reduce WEP; (2) chitosan dissolved in acetic acid (0.005, 0.01, 0.02, and 0.05 g mL-1) does not decrease WEP at any point during a 7 week incubation period; and (3) chitosan in a powder form reaches its full effectiveness after three weeks of incubation. Chitosan could be an effective coamendment to poultry litter with other treatments in order to reduce WEP

    Bacteria Monitoring in the Upper Illinois River Watershed

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    This project focuses on the Upper Illinois River Watershed (UIRW; HUC 11110103), which is within the Boston Mountains and Ozark Highlands ecoregions in northwest Arkansas. Headwaters of the Illinois River originate near Hogeye, Arkansas and flow north through Savoy, then west into Oklahoma near Watts. The UIRW drains an area of 1952 km2 , of which 50.3% is pasture and grassland, 35.9% is forest, 8.8% is urban and suburban, 4.3% is transitional and 0.3% is water (Arkansaswater.org, 2015). Land use throughout the watershed is also changing, with increases in residential, commercial and industrial development. The IRW has been designated a priority watershed for the Arkansas Natural Resources Commission (ANRC) 319 Nonpoint Source Program

    Bohr-Sommerfeld Quantization of Space

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    We introduce semiclassical methods into the study of the volume spectrum in loop gravity. The classical system behind a 4-valent spinnetwork node is a Euclidean tetrahedron. We investigate the tetrahedral volume dynamics on phase space and apply Bohr-Sommerfeld quantization to find the volume spectrum. The analysis shows a remarkable quantitative agreement with the volume spectrum computed in loop gravity. Moreover, it provides new geometrical insights into the degeneracy of this spectrum and the maximum and minimum eigenvalues of the volume on intertwiner space.Comment: 32 pages, 10 figure

    Learning volition: A longitudinal study of developing intentional awareness in Tourette syndrome

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    Tourette syndrome (TS) is characterized by the presence of involuntary movements (tics) which are, at least partly, generated within ‘voluntary’ motor pathways. Here we reassess 16 TS patients (age 19 ± 2.3 years) who participated in a mental chronometry study of volition 5.5 years previously (Ganos C et al. Cortex. 2015 Mar.; 64:47–54), and 16 age-matched controls. Participants estimated the time of their own voluntary movements (Libet's M judgement), or of conscious intention to make voluntary movements (Libet's W judgement), in separate blocks. We considered M judgement as a control condition. Therefore, the experience of an intention to move occurring prior to actual movement onset, as measured by the W-M gap, was taken as the cardinal feature of volition. Time estimates of the TS group did not differ significantly from controls, for either M or W judgement. Further, M and W time estimates in the TS group had not changed significantly between the two assessments. However, exploratory analyses revealed a strong relation between disease duration and the development of M- and W-judgements: the longer was the disease duration, the less was the developmental increase in the W-M gap (linear regression, p = .003). In conclusion, our results suggest compromised development of experience of volition in developing TS patients. The developmental difficulty in processing internal premotor signals for voluntary actions could reflect the chronic persistence of tics from adolescence to adulthood

    Globular Cluster Ultraluminous X-ray Sources in the Furthest Early-Type Galaxies

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    Ultraluminous X-ray Sources (ULXs) in globular clusters are low mass X-ray binaries that achieve high X-ray luminosities through a currently uncertain accretion mechanism. Using archival Chandra and Hubble Space Telescope observations, we perform a volume-limited search (≲\lesssim 70 Mpc) of 21 of the most massive (>1011.5M⊙>10^{11.5} M_\odot) early-type galaxies to identify ULXs hosted by globular cluster (GC) candidates. We find a total of 34 ULX candidates above the expected background within 5 times the effective radius of each galaxy, with 10 of these (∼29.4%\sim29.4\%) potentially hosted by a GC. A comparison of the spatial and luminosity distributions of these new candidate GC ULXs with previously identified GC ULXs shows that they are similar: both samples peak at LX∼L_X \sim a few ×1039\times 10^{39} erg/s and are typically located within a few effective radii of their host galaxies.Comment: Accepted for publication in MNRAS. 10 pages, 4 figures, 5 table
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