Source characterization of volatile organic compounds at Carlsbad Caverns National Park.

Carlsbad Caverns National Park (CAVE), located in southeastern New Mexico, experiences elevated ground-level ozone (O3) exceeding the National Ambient Air Quality Standard (NAAQS) of 70 ppbv. It is situated adjacent to the Permian Basin, one of the largest oil and gas (O&G) producing regions in the US. In 2019, the Carlsbad Caverns Air Quality Study (CarCavAQS) was conducted to examine impacts of different sources on ozone precursors, including nitrogen oxides (NOx) and volatile organic compounds (VOCs). Here, we use positive matrix factorization (PMF) analysis of speciated VOCs to characterize VOC sources at CAVE during the study. Seven factors were identified. Three factors composed largely of alkanes and aromatics with different lifetimes were attributed to O&G development and production activities. VOCs in these factors were typical of those emitted by O&G operations. Associated residence time analyses (RTA) indicated their contributions increased in the park during periods of transport from the Permian Basin. These O&G factors were the largest contributor to VOC reactivity with hydroxyl radicals (62%). Two PMF factors were rich in photochemically generated secondary VOCs; one factor contained species with shorter atmospheric lifetimes and one with species with longer lifetimes. RTA of the secondary factors suggested impacts of O&G emissions from regions farther upwind, such as Eagle Ford Shale and Barnett Shale formations. The last two factors were attributed to alkenes likely emitted from vehicles or other combustion sources in the Permian Basin and regional background VOCs, respectively.Implications: Carlsbad Caverns National Park experiences ground-level ozone exceeding the National Ambient Air Quality Standard. Volatile organic compounds are critical precursors to ozone formation. Measurements in the Park identify oil and gas production and development activities as the major contributors to volatile organic compounds. Emissions from the adjacent Permian Basin contributed to increases in primary species that enhanced local ozone formation. Observations of photochemically generated compounds indicate that ozone was also transported from shale formations and basins farther upwind. Therefore, emission reductions of volatile organic compounds from oil and gas activities are important for mitigating elevated O3 in the region.

Wintertime haze and ozone at Dinosaur National Monument.

Dinosaur National Monument (DINO) is located near the northeastern edge of the Uinta Basin and often experiences elevated levels of wintertime ground-level ozone. Previous studies have shown that high ozone mixing ratios in the Uinta Basin are driven by elevated levels of volatile organic compounds (VOCs) and nitrogen oxides (NOx) from regional oil and gas development coupled with temperature inversions and enhanced photochemistry from persistent snow cover. Here, we show that persistent snow cover and temperature inversions, along with abundant ammonia, also lead to wintertime haze in this region. A study was conducted at DINO from November 2018 through May 2020 where ozone, speciated fine and coarse aerosols, inorganic gases, and VOCs were measured. Three National Ambient Air Quality Standards (NAAQS) ozone exceedances were observed in the first winter, and no exceedances were observed in the second winter. In contrast, elevated levels of particulate matter were observed both winters, with 24-h averaged particle light extinction exceeding 100 Mm-1. These haze events were dominated by ammonium nitrate, and particulate organics were highly correlated with ammonium nitrate. Ammonium nitrate formation was limited by nitric acid in winter. As such, reductions in regional NOx emissions should reduce haze levels and improve visibility at DINO in winter. Long-term measurements of particulate matter from nearby Vernal, Utah, suggest that visibility impairment is a persistent issue in the Uinta Basin in winter. From April through October 2019, relatively clean conditions occurred, with average particle extinction of ~10 Mm-1. During this period, ammonium nitrate concentrations were lower by more than an order of magnitude, and contributions from coarse mass and soil to haze levels increased. VOC markers indicated that the high levels of observed pollutants in winter were likely from local sources related to oil and gas extraction activities.Implications: Elevated ground-level ozone and haze levels were observed at Dinosaur National Monument in winter. Haze episodes were dominated by ammonium nitrate, with 24-h averaged particle light extinction exceeding 100 Mm-1, reducing visual range near the surface to ~35 km. Despite elevated ammonium nitrate concentrations, additional gas-phase ammonia was available, such that any increase in NOx emissions in the region is likely to lead to even greater haze levels.

A review of measurements of air-surface exchange of reactive nitrogen in natural ecosystems across North America.

This review summarizes the state of the science of measurements of dry deposition of reactive nitrogen (Nr) compounds in North America, beginning with current understanding of the importance of dry deposition at the U.S. continental scale followed by a review of micrometeorological flux measurement methods. Measurements of Nr air-surface exchange in natural ecosystems of North America are then summarized, focusing on the U.S. and Canada. Drawing on this synthesis, research needed to address the incompleteness of dry deposition budgets, more fully characterize temporal and geographical variability of fluxes, and better understand air-surface exchange processes is identified. Our assessment points to several data and knowledge gaps that must be addressed to advance dry deposition budgets and air-surface exchange modeling for North American ecosystems. For example, recent studies of particulate (NO3-) and gaseous (NOx, HONO, peroxy nitrates) oxidized N fluxes challenge the fundamental framework of unidirectional flux from the atmosphere to the surface employed in most deposition models. Measurements in forest ecosystems document the importance of in-canopy chemical processes in regulating the net flux between the atmosphere and biosphere, which can result in net loss from the canopy. These results emphasize the need for studies to quantify within- and near-canopy sources and sinks of the full suite of components of the Nr chemical system under study (e.g., NOy or HNO3-NH3-NH4NO3). With respect to specific ecosystems and geographical locations, additional flux measurements are needed particularly in agricultural regions (NH3), coastal zones (NO3- and organic N), and arid ecosystems and along urban to rural gradients (NO2). Measurements that investigate non-stomatal exchange processes (e.g., deposition to wet surfaces) and the biogeochemical drivers of bidirectional exchange (e.g., NH3) are considered high priority. Establishment of long-term sites for process level measurements of reactive chemical fluxes should be viewed as a high priority long-term endeavor of the atmospheric chemistry and ecological communities.

Impact of Front Range sources on reactive nitrogen concentrations and deposition in Rocky Mountain National Park.

Human influenced atmospheric reactive nitrogen (RN) is impacting ecosystems in Rocky Mountain National Park (ROMO). Due to ROMO's protected status as a Class 1 area, these changes are concerning, and improving our understanding of the contributions of different types of RN and their sources is important for reducing impacts in ROMO. In July-August 2014 the most comprehensive measurements (to date) of RN were made in ROMO during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ). Measurements included peroxyacetyl nitrate (PAN), C1-C5 alkyl nitrates, and high-time resolution NOx, NOy, and ammonia. A limited set of measurements was extended through October. Co-located measurements of a suite of volatile organic compounds provide information on source types impacting ROMO. Specifically, we use ethane as a tracer of oil and gas operations and tetrachloroethylene (C2Cl4) as an urban tracer to investigate their relationship with RN species and transport patterns. Results of this analysis suggest elevated RN concentrations are associated with emissions from oil and gas operations, which are frequently co-located with agricultural production and livestock feeding areas in the region, and from urban areas. There also are periods where RN at ROMO is impacted by long-range transport. We present an atmospheric RN budget and a nitrogen deposition budget with dry and wet components. Total deposition for the period (7/1-9/30) was estimated at 1.58 kg N/ha, with 87% from wet deposition during this period of above average precipitation. Ammonium wet deposition was the dominant contributor to total nitrogen deposition followed by nitrate wet deposition and total dry deposition. Ammonia was estimated to be the largest contributor to dry deposition followed by nitric acid and PAN (other species included alkyl nitrates, ammonium and nitrate). All three species are challenging to measure routinely, especially at high time resolution.

Referential processing in the human brain: An Event-Related Potential (ERP) study.

A substantial body of ERP research investigating the processing of syntactic long-distance dependencies has shown that, across languages and construction types, the second element in such configurations typically elicits phasic left anterior negativity (LAN). We hypothesized that these effects are not specific to syntactic dependencies, but rather index a more general cognitive operation in which the second (dependent) element in sentence-level linguistic long-distance relationships triggers a process of association with the first element. We tested this hypothesis with straightforward referential dependencies, comparing pronouns with proper name antecedents to those without, and proper names with and without preceding co-referring pronouns. We predicted phasic LAN effects in response to the second referential element in both comparisons, but observed them only in response to pronouns with antecedents; no differences were observed between responses to proper names with and without preceding co-referring pronouns. We argue that LAN effects observed at the pronoun index the cognitive operations necessary for the association of a pronoun with its antecedent, on which it depends for its reference. Similar but non-identical responses were elicited by the main clause verb following the gap position in object relative clause constructions compared to coordinate clause controls in an orthogonal manipulation. LAN effects were thus elicited by the second dependent element in both construction types, suggesting that long-distance syntactic and referential dependencies pose similar processing challenges. These findings help to clarify the cognitive processes indexed by anterior negative responses to associated dependent elements in a variety of language contexts.

Extractive FTIR spectroscopy with cryogen-free low-temperature inert preconcentration for autonomous measurements of atmospheric organics: 1: Instrument development and preliminary performance.

In collaboration with the Jefferson County Department of Health and the Environmental Protection Agency (EPA), the University of Alabama in Huntsville developed a novel sensor for detecting very low levels of volatile organic compounds (VOCs). This sensor uses a commercial Fourier-transform infrared (FTIR) spectrometer, a commercial long-path IR gas cell, a commercial acoustic Stirling cyrocooler, and a custom cryogen-free cryotrap to improve sensitivity in an autonomous system with on-board quality control and quality assurance. Laboratory and initial field results show this methodology is sensitive to and well-suited for a wide variety of VOC atmospheric research and monitoring applications, including EPA National Air Toxics Trends Stations and the National Core monitoring network.

Impact of Marcellus Shale natural gas development in southwest Pennsylvania on volatile organic compound emissions and regional air quality.

The Marcellus Shale is the largest natural gas deposit in the U.S. and rapid development of this resource has raised concerns about regional air pollution. A field campaign was conducted in the southwestern Pennsylvania region of the Marcellus Shale to investigate the impact of unconventional natural gas (UNG) production operations on regional air quality. Whole air samples were collected throughout an 8050 km(2) grid surrounding Pittsburgh and analyzed for methane, carbon dioxide, and C1-C10 volatile organic compounds (VOCs). Elevated mixing ratios of methane and C2-C8 alkanes were observed in areas with the highest density of UNG wells. Source apportionment was used to identify characteristic emission ratios for UNG sources, and results indicated that UNG emissions were responsible for the majority of mixing ratios of C2-C8 alkanes, but accounted for a small proportion of alkene and aromatic compounds. The VOC emissions from UNG operations accounted for 17 ± 19% of the regional kinetic hydroxyl radical reactivity of nonbiogenic VOCs suggesting that natural gas emissions may affect compliance with federal ozone standards. A first approximation of methane emissions from the study area of 10.0 ± 5.2 kg s(-1) provides a baseline for determining the efficacy of regulatory emission control efforts.

Phenol groups in northeastern U.S. submicrometer aerosol particles produced from seawater sources.

Atmospheric particles collected during the ICARTT 2004 field experiment at ground based sites at Appledore Island (AI), New Hampshire, Chebogue Point (CP), Nova Scotia, and aboard the R/V Ronald Brown (RB) were analyzed using Fourier transform infrared (FTIR) spectroscopy to quantify organic mass (OM) and organic functional groups. Several of these spectra contain a unique absorbance peak at 3500 cm(-1). Laboratory calibrations identify this peak with phenol functional groups. The phenol groups are associated with seawater-derived emissions based on correlations with tracer volatile organic compounds (VOCs) and ions, and potential source contribution function (PSCF) analysis. On the basis of the measured absorptivities, the project average phenol group concentrations are 0.24 +/- 0.18 microg m(-3) (4% of the total OM) at AI, 0.10 +/- 0.6 microg m(-3) (5% of the total OM) at CP, and 0.08 +/- 0.09 microg m(-3) (2% of the total OM) on board the RB, with detection limits typically between 0.06 and 0.11 microg m(-3). The spectra were partitioned into three primary factors using positive matrix factorization (PMF) sufficient to explain more than 95% of the measured OM. The fossil fuel combustion factor contributed 40% (AI), 34% (CP), and 43% (RB) of the total OM; the terrestrial biogenic factor contributed 20% (AI), 30% (CP), and 27% (RB). The seawater-derived factor contributed 40% (AI), 36% (CP) and 29% (RB) of the OM and showed similar correlations to tracers as the phenol group.

Air toxic emissions from snowmobiles in Yellowstone National Park.

A study on emissions associated with oversnow travel in Yellowstone National Park (YNP) was conducted for the time period of February 13-16, 2002 and February 12-16, 2003. Whole air and exhaust samples were characterized for 85 volatile organic compounds using gas chromatography. The toxics including benzene, toluene, ethylbenzene, xylenes (p-, m-, and o-xylene), and n-hexane, which are major components of two-stroke engine exhaust, show large enhancements during sampling periods resulting from increased snowmobile traffic. Evaluation of the photochemical history of air masses sampled in YNP revealed that emissions of these air toxics were (i) recent, (ii) persistent throughout the region, and (iii) consistent with the two-stroke engine exhaust sample fingerprints. The annual fluxes were estimated to be 0.35, 1.12, 0.24, 1.45, and 0.36 Gg yr(-1) for benzene, toluene, ethylbenzene, xylenes, and n-hexane, respectively, from snowmobile usage in YNP. These results are comparable to the flux estimates of 0.23, 0.77, 0.17, and 0.70 Gg yr(-1) for benzene, toluene, ethylbenzene, and xylenes, respectively, that were derived on the basis of (i) actual snowmobile counts in the Park and (ii) our ambient measurements conducted in 2003. Extrapolating these results, annual emissions from snowmobiles in the U.S. appear to be significantly higher than the values from the EPA National Emissions Inventory (1999). Snowmobile emissions represent a significant fraction ( approximately 14-21%) of air toxics with respect to EPA estimates of emissions by nonroad vehicles. Further investigation is warranted to more rigorously quantify the difference between our estimates and emission inventories.

Blowing smoke in Yellowstone: air quality impacts of oversnow motorized recreation in the park.

Snowmobile use in Yellowstone National Park has been shown to impact air quality, with implications for the safety and welfare of Park staff and other Park resource values. Localized impacts have been documented at several high-use sites in the Park, but the broader spatial variability of snowmobile emissions and air quality was not understood. Measurements of 87 volatile organic compounds (VOCs) were made for ambient air sampled across the Park and West Yellowstone, Montana, during 2 days of the 2002-2003 winter use season, 1 year before the implementation of a new snowmobile policy. The data were compared with similar data from pristine West Coast sites at similar latitudes. Backward trajectories of local air masses, alkyl nitrate-parent alkane ratios, and atmospheric soundings were used to identify the VOC sources and assess their impact. Different oversnow vehicle types used in the Park were sampled to determine their relative influence on air mass pollutant composition. VOCs were of local origin and demonstrated strong spatiotemporal variability that is primarily influenced by levels of snowmobile traffic on given road segments at different times of day. High levels of snowmobile traffic in and around West Yellowstone produced consistently high levels of benzene, toluene, and carbon monoxide.

Development of a cryogen-free concentration system for measurements of volatile organic compounds.

An innovative cryogen-free concentrator system for measurement of atmospheric trace gases at the parts per trillion level has been developed with detection by routinely used gas chromatographic methods. The first-generation system was capable of reaching a trapping temperature of -186 degrees C, while the current version can reach -195 degrees C. A Kleemenko cooler is used to create liquid nitrogen equivalent trapping conditions and eliminate the use of solid absorbents, a potential source of artifacts. The method utilizes dual-stage trapping with individual cold regions. The two stages are cooled to -20 and -175 degrees C for water management and sample enrichment, respectively. Both stages house a Silonite-coated stainless steel sample loop; the second stage loop is filled with 1-mm-diameter glass beads, which provide an inert surface area for analyte concentration. In our application, the complete system employed four channels utilizing two flame ionization detectors, one electron capture detector, and a mass spectrometer. The system was automated for unattended operation and was deployed off the New England east coast on Appledore Island to measure a suite of ambient non-methane hydrocarbons, halocarbons, alkyl nitrates, and oxygenated volatile organic compounds during the International Consortium for Atmospheric Research on Transport and Transformation field campaign in summer 2004. This robust system quantified 98 ambient volatile organic compounds with precisions ranging from 0.3 to 15%.

Vascular risks and incident dementia: results from a cohort study of the very old.

The contribution of vascular pathology to the manifestation of dementia and the importance of vascular risk to measures of cognitive function is being increasingly recognized. In particular, confirmation of this risk points towards approaches for prevention in large sections of the population. Information on determinants of incident dementia is increasing, but still relatively few studies of risk have been based on incident cases of dementia in very elderly populations. In this study based on incident cases of dementia in a population aged 75 and over, vascular risks were obtained from informants of the respondents with incident dementia. When compared with controls the factors associated with incident dementia were history of heart attack (odds ratio 2.9), transient ischaemic attacks (4.8), cerebrovascular accidents (3.4), family history of first-degree relatives with dementia (4.0), and occupational exposure to vibrating instruments (1.4). If only Alzheimer's disease, clinically diagnosed, was included, diabetes (1.4) and a history of dementia in first-degree relatives (6.6) emerged. Thus, vascular risk continues to be of importance in the oldest age groups.

Incidence of clinically diagnosed subtypes of dementia in an elderly population. Cambridge Project for Later Life.

BACKGROUND: In developed countries, most dementia appears to be due to Alzheimer's disease and vascular dementia. We report rates for incidence of subtypes of dementia based on clinical diagnosis. METHOD: This study was a 2.4-year (s.d. 2.6 months) follow-up of a cohort aged 75 years and over, seen initially in a prevalence study of dementia. A screening interview in 1173 survivors was followed in a subsample of 461 respondents by a diagnostic interview 1.8 months after screening (s.d. 1.5 months). This comprised a standardised interview with respondent and informant, with venepuncture where possible. Clinical diagnoses of subtypes were made by specified criteria. RESULTS: The incidence of Alzheimer's disease of mild and greater severity was 2.7/1000 person-years at risk (1.6-4.4); in men 1.5 (0.8-2.7) and in women 3.3 (1.8-5.9). The incidence of vascular dementia was 1.2/100 person-years at risk (0.7-1.9); in men 1.1 (0.4-2.8) and in women 1.2 (0.7-2.0). Alzheimer's disease, but not vascular dementia, showed a marked increase with age, particularly in women. Rates for minimal dementia of different subtypes showed similar age and sex effects, but were much higher for Alzheimer's disease than vascular dementia. CONCLUSIONS: The striking rise in incidence rates of dementia in the very old appear to be due to Alzheimer's disease, while rates for vascular dementia remain relatively constant. These trends are particularly marked for minimal dementia, but emphasise the importance of Alzheimer's disease in the community as a cause of cognitive decline of all degrees.

The prevalence of depression in a cohort of the very elderly.

In a community study of 1173 very elderly (> or = 77 years) subjects, a screening interview was followed by a CAMDEX diagnostic interview in a subsample of 461. The estimated prevalence of DSM-III-R major depressive disorder in the community sampled was 2.4% (95% CI 0.9%, 4.0%). Using CAMDEX criteria, the prevalence of depressive illness was 3.0% (95% CI 0.7%, 5.3%). 10% of those who had a diagnostic interview were rated as having depressive symptoms of mild or moderate severity. Of these, approximately 1/3 met diagnostic criteria for major depressive disorder. The significance of these findings and the possible need for wider criteria for depression in the elderly are discussed.

Incidence of dementia in a population older than 75 years in the United Kingdom.

BACKGROUND: Incidence studies have been relatively neglected in psychiatric epidemiology. They are particularly important for dementia, since prevalence rates are affected by length of survival, which itself falls with increasing age and presence of dementia. METHODS: Two-wave community study of 1195 elderly subjects aged older than 75 years, restudied 2.4 years after a community prevalence study. A two-stage method was used, comprising the Mini-Mental State Examination followed in a stratified sample by the Cambridge Examination for Mental Disorders of the Elderly (CAM-DEX) interview. Incidence rates were based on person-years at risk. RESULTS: Annual incidence rates for dementia were 2.3% for subjects initially aged 75 to 79 years, 4.6% for ages 80 to 84 years, and 8.5% for ages 85 to 89 years, approximately doubling every 5 years. Rates did not differ significantly by sex, educational level, or social class. Twice as many additional individuals received a diagnosis of minimal dementia not reaching case threshold. CONCLUSIONS: The findings show high rates of new onset dementia, increasing markedly with age, and suggest rapid acceleration of one or more processes that is common in advanced age.

Future imperfect: the long-term outcome of depression.

During 1976, 80 patients with a primary depressive illness were selected from a consecutive series of referrals to the Royal Edinburgh Hospital for a short-term follow-up study. This paper concerns the 12-year longitudinal assessment of the survivors. During the follow-up, mortality risk for the sample was almost doubled. Of the series, 35% had experienced a recurrence within 2 years of the initial interview, and just over 60% within the entire study time of 12 years. The risk of recurrence was enhanced for those aged over 45 years at index, for those with a history of depressive disorder and for those who had not engaged in parasuicidal behaviour during the index episode. The observed effect of previous episodes was largely accounted for by age. The chance of recurrence was not affected by whether the treatment of the index episode included ECT, or by whether diagnosis was 'endogenous' or 'neurotic'. Application of the Lee-Murray outcome criteria showed that about one-third of the Edinburgh series experienced a very poor outcome. Results are presented concerning the prediction of long-term outcome as represented by the Depression Outcome Scale (DOS), a measure specially constructed for this study.

Testicular torsion and its effects on contralateral testicle.

Twenty-six male adult Noble (Nb) rats underwent unilateral left testicular torsion of 720 degrees. The testicles of the 6 control animals were immediately detorsed. The experimental animals were divided into 4 groups according to the surgical approach (abdominal vs. scrotal) and location where the torsed testicle was placed (abdomen vs. scrotum). After six hours all torsed testicles in the experimental groups were detorsed. One month later all animals were sacrificed, and the contralateral testicles were examined for spermatogenesis and mean seminiferous tubular diameter. All groups displayed decreased spermatogenesis with smaller mean seminiferous tubular diameter as compared with the control group.

Flow cytometric analysis of primary and metastatic bladder cancer.

A total of 22 patients with high grade P2-4N+ transitional cell carcinoma of the bladder underwent flow cytometric analysis of nuclei obtained from paraffin embedded specimens from the primary (bladder) and metastatic (lymph node) sites. Tumor heterogeneity was defined as polyclonal aneuploidy of the primary tumor (not identified in the population studied) or as a difference in the deoxyribonucleic acid index of the primary and metastatic sites of 0.20 or more (8 patients). With these criteria 8 patients (36%) had heterogeneous tumors and 14 (64%) had homogeneous tumors. The median survival of 14 patients with aneuploid and 8 with diploid primary tumors was 17.5 and 8.0 months, respectively (p equals 0.08, Lee-Desu test). When patient survival was compared to the ploidy of the metastatic site, or in patients with diploid primary and metastatic lesions versus deoxyribonucleic acid aneuploidy at either the primary and/or metastatic site, the aneuploid tumors had a longer survival but this difference was not significant (p equals 0.13 and 0.23, respectively). Our study demonstrates the value of flow cytometry to identify primary metastatic tumor heterogeneity. It also suggests that the presence of metastasis may be a more important factor to define the biological potential of transitional cell carcinoma than is deoxyribonucleic acid ploidy.

Coumarin necrosis of the penis.

Coumarin-induced necrosis of the skin and subcutaneous tissue is an uncommon but well recognized complication of anticoagulant therapy. Although any area of skin may be involved necrosis of the penis is rare. We report a case of penile necrosis associated with coumarin therapy and review the literature.

Low molecular weight polyethylene. Cause for wear in a total hip replacement case.

The problem of acetabular wear in a 50-year-old man with bilateral total hip arthroplasties is presented. Wear is generally demonstrated by in vitro testing. Ultrahigh molecular weight polyethylene is the preferred material and should be considered the standard material for arthroplasty.