Mobile sediments in a karst aquifer

In karst aquifers, mobile sediments may play a fundamental role in determining water quality by concentrating and transporting contaminants. This study investigates spatial characteristics of sediment in a karst aquifer, examines temporal characteristics of sediment discharging from a karst spring, and describes a new method for tracing sediment in karst terrane. Sediment samples were collected from different compartments of a karst aquifer (the Edwards Aquifer, Central Texas) and analyzed for mineralogy, grainsize distribution, organic carbon content, and specific surface area. Suspended sediment samples discharging from a karst spring in response to two storms were analyzed for mineralogy and grainsize distribution. To test the hypothesis that allochthonous sediment can move through karst systems, a sediment tracer--montmorillonite clay homoionized to the lanthanide form--was developed. Statistical analysis of sediment characteristics separated the sampling sites into three groups: 1) streambeds, sinkholes, and small springs; 2) wells; and 3) caves. Characteristics of sediments from Barton Springs (the main spring in the region) showed a mixture of the characteristics of these three groups. The mineralogic signature of sediments discharging from Barton Springs in response to storms was initially allochthonous and then became more autochthonous. Temporal changes in aqueous chemistry of Barton Springs varied in response to rainfall, seasonal changes in aquifer level, and draining of the pool over the spring. The results indicate that some sediments, containing calcite and a high organic carbon content, are allochthonous, and others, containing dolomite and a low organic carbon content, are autochthonous. Sediments issuing from Barton Springs contain a mix of both allochthonous and autochthonous sediments. Based on geochemical characteristics, allochthonous sediments have a greater potential to sorb and transport contaminants than do autochthonous sediments. Development and testing of the sediment tracer verified that allochthonous sediments can be transported through karst. Sediments, particularly allochthonous sediments, can play a crucial role in contaminant transport in karst; the volume of these sediments will increase with increasing urbanization. Because those sediment characteristics which determine contaminant transport potential vary both spatially and temporally, determination of sediment volume and type is critical to evaluating its impact on water quality.Geological Science

Public Perceptions on the Ideal Balance between Natural Resource Protection and Use in the Western USA

Attitudes of Western residents of the USA toward natural resources have been changing due to changes in demographics and rapid population growth in the region. The objective of the study reported here was to determine how residents in 15 Western states view the balance between natural resource exploitation and protection. In general, natural resource protection was more important than resource use for people having the following demographic characteristics: (1) female, (2) younger than 60, (3) more formally educated, and (4) residing in communities larger than 25,000

Carbonaceous material fractions in sediments and their effect on the sorption and persistence of organic pollutants in small urban watersheds

U.S. Department of the InteriorU.S. Geological SurveyOpe

PAHs underfoot: Contaminated dust from coal-tar sealcoated pavement is widespread in the United States

We reported in 2005 that runoff from parking lots treated with coal-tar-based sealcoat was a major source of polycyclic aromatic hydrocarbons (PAHs) to streams in Austin, Texas. Here we present new data from nine U.S. cities that show nationwide patterns in concentrations of PAHs associated with sealcoat. Dust was swept from parking lots in six cities in the central and eastern U.S., where coal-tar-based sealcoat dominates use, and three cities in the western U.S., where asphaltbased sealcoat dominates use. For six central and eastern cities, median ΣPAH concentrations in dust from sealcoated and unsealcoated pavement are 2200 and 27 mg/kg, respectively. For three western cities, median ΣPAH concentrations in dust from sealcoated and unsealcoated pavement are similar and very low (2.1 and 0.8 mg/kg, respectively). Lakes in the central and eastern cities where pavement was sampled have bottom sediments with higher PAH concentrations than do those in the western cities relative to degree of urbanization. Bottom-sediment PAH assemblages are similar to those of sealcoated pavement dust regionally, implicating coal-tar-based sealcoat as a PAH source to the central and eastern lakes. Concentrations of benzo[a]pyrene in dust from coal-tar sealcoated pavement and adjacent soils greatly exceed generic soil screening levels, suggesting that research on human-health risk is warranted

European Surveillance System on Contact Allergies (ESSCA): Characteristics of patients patch tested and diagnosed with irritant contact dermatitis

Background Irritant contact dermatitis (ICD) is caused by the acute locally toxic effect of a strong irritant, or the cumulative exposure to various weaker physical and/or chemical irritants. Objectives To describe the characteristics of patients with ICD in the population patch tested in the European Surveillance System on Contact Allergies (ESSCA; ) database. Methods Data collected by the ESSCA in consecutively patch-tested patients from January 2009 to December 2018 were analyzed. Results Of the 68 072 patients, 8702 were diagnosed with ICD (without concomitant allergic contact dermatitis [ACD]). Hand and face were the most reported anatomical sites, and 45.7% of the ICD was occupational ICD (OICD). The highest proportions of OICD were found in metal turners, bakers, pastry cooks, and confectionery makers. Among patients diagnosed with ICD, 45% were found sensitized with no relevance for the current disease. Conclusions The hands were mainly involved in OICD also in the subgroup of patients with contact dermatitis, in whom relevant contact sensitization had been ruled out, emphasizing the need for limiting irritant exposures. However, in difficult-to-treat contact dermatitis, unrecognized contact allergy, or unrecognized clinical relevance of identified allergies owing to incomplete or wrong product ingredient information must always be considered

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

Current patch test results with the European baseline series and extensions to it from the 'European Surveillance System on Contact Allergy' network, 2007-2008

BACKGROUND: The pattern of contact sensitization to the supposedly most important allergens assembled in the baseline series differs between countries, presumably at least partly because of exposure differences. Objectives. To describe the prevalence of contact sensitization to allergens tested in consecutive patients in the years 2007 and 2008, and to discuss possible differences. METHODS: Data from the 39 departments in 11 European countries comprising the European Surveillance System on Contact Allergy network (www.essca-dc.org) in this period have been pooled and analysed according to common standards. RESULTS: Patch test results with the European baseline series, and country-specific or department-specific additions to it, obtained in 25 181 patients, showed marked international variation. Metals and fragrances are still the most frequent allergens across Europe. Some allergens tested nationally may be useful future additions to the European baseline series, for example methylisothiazolinone, whereas a few long-term components of the European baseline series, namely primin and clioquinol, no longer warrant routine testing. CONCLUSIONS: The present analysis points to 'excess' prevalences of specific contact sensitization in some countries, although interpretation must be cautious if only few, and possibly specialized, centres are representing one country. A comparison as presented may help to target in-depth research into possible causes of 'excess' exposure, and/or consideration of methodological issues, including modifications to the baseline series