Visibility-reducing organic aerosols in the vicinity of Grand Canyon National Park: Properties observed by high resolution gas chromatography

Fine particle and total airborne particle samples were collected during August 1989 within the Grand Canyon (Indian Gardens (IG)) and on its south rim (Hopi Point (HP)) to define summertime organic aerosol concentration and composition as a function of elevation at Grand Canyon National Park. Inorganic chemical constituents were analyzed also to help place the relative importance of organics in perspective. Fine particle organic aerosols were approximately equal in concentration to sulfate aerosols at both sites. Monthly average mass concentrations for fine aerosol organics ranged from 1.1 μg m(−3) (IG) to 1.3 μg m^(−3) (HP), while the organic aerosol concentration within total suspended particulate matter samples ranged from 1.9 μg m^(−3) (IG) to 2.1 μg m^(−3) (HP). Aerosol organics that could be evaluated by gas chromatography with flame ionization detection (GC-FID) (elutable organics) constituted 27% to 53% of the total organics mass collected as fine or total aerosol. At each site, roughly half of the elutable organics fine aerosol fraction was composed of highly polar organic compounds. Distributions of the elutable organics were compared to Los Angeles fine aerosol samples and to distributions of authentic sources of aerosol organics. It was found that the Grand Canyon organic aerosol during August 1989 did not resemble diluted aged Los Angeles organic aerosol, indicating that most of the organic particulate matter at the Grand Canyon at the time studied originated from other sources

Mathematical modeling of atmospheric fine particle-associated primary organic compound concentrations

An atmospheric transport model has been used to explore the relationship between source emissions and ambient air quality for individual particle phase organic compounds present in primary aerosol source emissions. An inventory of fine particulate organic compound emissions was assembled for the Los Angeles area in the year 1982. Sources characterized included noncatalyst- and catalyst-equipped autos, diesel trucks, paved road dust, tire wear, brake lining dust, meat cooking operations, industrial oil-fired boilers, roofing tar pots, natural gas combustion in residential homes, cigarette smoke, fireplaces burning oak and pine wood, and plant leaf abrasion products. These primary fine particle source emissions were supplied to a computer-based model that simulates atmospheric transport, dispersion, and dry deposition based on the time series of hourly wind observations and mixing depths. Monthly average fine particle organic compound concentrations that would prevail if the primary organic aerosol were transported without chemical reaction were computed for more than 100 organic compounds within an 80 km × 80 km modeling area centered over Los Angeles. The monthly average compound concentrations predicted by the transport model were compared to atmospheric measurements made at monitoring sites within the study area during 1982. The predicted seasonal variation and absolute values of the concentrations of the more stable compounds are found to be in reasonable agreement with the ambient observations. While model predictions for the higher molecular weight polycyclic aromatic hydrocarbons (PAH) are in agreement with ambient observations, lower molecular weight PAH show much higher predicted than measured atmospheric concentrations in the particle phase, indicating atmospheric decay by chemical reactions or evaporation from the particle phase. The atmospheric concentrations of dicarboxylic acids and aromatic polycarboxylic acids greatly exceed the contributions that are due to direct emissions from primary sources, confirming that these compounds are principally formed by atmospheric chemical reactions

Contribution of primary aerosol emissions from vegetation-derived sources to fine particle concentrations in Los Angeles

Field measurements of the n-alkanes present in fine atmospheric aerosols show a predominance of odd carbon numbered higher molecular weight homologues (C_(27)–C_(33)) that is characteristic of plant waxes. Utilizing a local leaf wax n-alkane profile in conjunction with an air quality model, it is estimated that, at most, 0.2–1.0 μg m^(−3) of the airborne fine particulate matter (d_p < 2.1 μm) present in the Los Angeles basin could originate from urban vegetative detritus; this corresponds to approximately 1–3% of the total ambient fine aerosol burden. However, some of the observed vegetation aerosol fingerprint in the Los Angeles air may be due in part to emissions from food cooking rather than plant detritus. Seasonal trends in the ambient n-alkane patterns are examined to seek further insight into the relative importance of anthropogenic versus natural sources of vegetation-derived fine particulate matter

Determination of Organic Compounds Present in Airborne Particulate Matter

Fine organic aerosol samples (d_p ≤ 2.1 µm) were collected systematically during the entire year 1982 at four urban sites in the greater Los Angeles area and at one remote station: West Los Angeles, Downtown Los Angeles, Pasadena, Rubidoux, and San Nicolas Island. Samples were taken at 6-day intervals and composited to form monthly sample sets. The aerosol sample composites were subjected to high resolution gas chromatography (HRGC) and gas chromatography/rnass spectrometry (GC/MS). The objective is to quantify the abundance and seasonal variation of individual organic compounds that may be diagnostic for the contribution of particular emission sources to the ambient organic complex. More than 80 organic compounds are quantified, including the series of a-alkanes, g-alkanoic acids, n-alkenoic acids, n-alkanals, and aliphatic dicarboxylic acids, as well as aromatic polycarboxylic acids, diterpenoids, polycyclic aromatic hydrocarbons, polycyclic aromatic ketones and quinones, nitrogen-containing organic compounds, and other organics. Primary organic aerosol constituents are readily identified, revealing an annual pattern with high winter concentrations and low summer concentrations in the Los Angeles area. In contrast, dicarboxylic acids of likely secondary origin show a reverse pattern, with high concentration in late spring/early summer. The total ambient annual average dicarboxylic acids concentration shows a steady increase when moving in the prevailing summer downwind direction from the most western urban sampling site (West Los Angeles) to the farthest eastern sampling location (Rubidoux), with an increase from 199 ng m^(-3) at West Los Angeles to 312 ng m^(-3) at Rubidoux. The occurrence of aromatic polycarboxylic acids in the fine particulate matter is discussed in detail in this study, including possible sources and formation pathways. The total aromatic polycarboxylic acid concentration reveals elevated summer concentrations when compared to the annual concentration cycle, indicating increased formation or/and emissions in summertime. Polycyclic aromatic hydrocarbons (PAH's), without exception, show low summer and high winter concentrations; whereas, polycyclic aromatic ketones (PAK's) and quinones (PAQ's) show slightly increased input/formation during early summer, indicating possible atmospheric chemical reactions involving PAH's as precursor compounds. Molecular markers characteristic of wood smoke are identified, and their concentrations change by season in close agreement with prior estimates of the seasonal use of wood as a fuel. The total mass concentration of identified aerosol organic compounds ranges from about 650 ng m^(-3) (West LA) to about 760 ng m^(-3) (Downtown LA) on an annual basis. Subdividing the total identified masses into their single compound classes reveals that n-alkanoic acids and aliphatic dicarboxylic acids make up the main portions quantified, followed by aromatic polycarboxylic acids, n-alkanes, diterpenoid acids, and polycyclic aromatic hydrocarbons. This compilation of fine organic aerosol data on a molecular level provides an extensive catalog of the organic compounds quantified, covering an entire year. Further research is underway to characterize the organic aerosol released by primary emission sources in the Los Angeles area. That study will not only provide complete characterizations of these emissions sources on a molecular basis, but in addition will enable the identification and quantification of additional organic compounds in the same airborne particle samples which otherwise would have gone unidentified in the complexity of the organic matrix inherent in fine airborne particle samples. In the future, these data from the monitoring network can be used to evaluate the predictions of mathematical models for the atmospheric transport and reaction of organic aerosol constituents defined at a molecular level

Urinary Bisphenol A and Type-2 Diabetes in U.S. Adults: Data from NHANES 2003-2008

Bisphenol A (BPA) is found in plastics and other consumer products; exposure may lead to insulin resistance and development of type-2 diabetes mellitus (T2DM) through over-activation of pancreatic β-cells. Previous studies using data from the National Health and Nutrition Examination Survey (NHANES) showed an inconsistent association between prevalence of self-reported T2DM and urinary BPA. We used a different diagnosis method of T2DM (hemoglobin A1c (HbA1c)) with a larger subset of NHANES.We analyzed data from 4,389 adult participants who were part of a sub-study of environmental phenol measurements in urine from three NHANES cycles from 2003 to 2008. T2DM was defined as having a HbA1c ≥6.5% or use of diabetes medication. The weighted prevalence of T2DM was 9.2%. Analysis of the total sample revealed that a two-fold increase in urinary BPA was associated with an odds ratio (OR) of 1.08 of T2DM (95% confidence interval (CI), 1.02 to 1.16), after controlling for potential confounders. However, when we examined each NHANES cycle individually, we only found a statistically significant association in the 2003/04 cycle (n = 1,364, OR = 1.23 (95% CI, 1.07 to 1.42) for each doubling in urinary BPA). We found no association in either the NHANES cycle from 2005/06 (n = 1,363, OR = 1.05 (95% CI, 0.94 to 1.18)); or 2007/08 (n = 1,662, OR = 1.06 (95% CI, 0.91 to 1.23)). Similar patterns of associations between BPA and continuous HbA1c were also observed.Although higher urinary BPA was associated with elevated HbA1c and T2DM in the pooled analysis, it was driven by data from only one NHANES cycle. Additional studies, especially of a longitudinal design with repeated BPA measurements, are needed to further elucidate the association between BPA and T2DM

Effect of aliskiren on post-discharge outcomes among diabetic and non-diabetic patients hospitalized for heart failure: insights from the ASTRONAUT trial

Aims The objective of the Aliskiren Trial on Acute Heart Failure Outcomes (ASTRONAUT) was to determine whether aliskiren, a direct renin inhibitor, would improve post-discharge outcomes in patients with hospitalization for heart failure (HHF) with reduced ejection fraction. Pre-specified subgroup analyses suggested potential heterogeneity in post-discharge outcomes with aliskiren in patients with and without baseline diabetes mellitus (DM). Methods and results ASTRONAUT included 953 patients without DM (aliskiren 489; placebo 464) and 662 patients with DM (aliskiren 319; placebo 343) (as reported by study investigators). Study endpoints included the first occurrence of cardiovascular death or HHF within 6 and 12 months, all-cause death within 6 and 12 months, and change from baseline in N-terminal pro-B-type natriuretic peptide (NT-proBNP) at 1, 6, and 12 months. Data regarding risk of hyperkalaemia, renal impairment, and hypotension, and changes in additional serum biomarkers were collected. The effect of aliskiren on cardiovascular death or HHF within 6 months (primary endpoint) did not significantly differ by baseline DM status (P = 0.08 for interaction), but reached statistical significance at 12 months (non-DM: HR: 0.80, 95% CI: 0.64-0.99; DM: HR: 1.16, 95% CI: 0.91-1.47; P = 0.03 for interaction). Risk of 12-month all-cause death with aliskiren significantly differed by the presence of baseline DM (non-DM: HR: 0.69, 95% CI: 0.50-0.94; DM: HR: 1.64, 95% CI: 1.15-2.33; P < 0.01 for interaction). Among non-diabetics, aliskiren significantly reduced NT-proBNP through 6 months and plasma troponin I and aldosterone through 12 months, as compared to placebo. Among diabetic patients, aliskiren reduced plasma troponin I and aldosterone relative to placebo through 1 month only. There was a trend towards differing risk of post-baseline potassium ≥6 mmol/L with aliskiren by underlying DM status (non-DM: HR: 1.17, 95% CI: 0.71-1.93; DM: HR: 2.39, 95% CI: 1.30-4.42; P = 0.07 for interaction). Conclusion This pre-specified subgroup analysis from the ASTRONAUT trial generates the hypothesis that the addition of aliskiren to standard HHF therapy in non-diabetic patients is generally well-tolerated and improves post-discharge outcomes and biomarker profiles. In contrast, diabetic patients receiving aliskiren appear to have worse post-discharge outcomes. Future prospective investigations are needed to confirm potential benefits of renin inhibition in a large cohort of HHF patients without D

Sequential Derivatization of Polar Organic Compounds in Cloud Water Using O-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine Hydrochloride, N, O-Bis(trimethylsilyl)trifluoroacetamide, and Gas-Chromatography/Mass Spectrometry Analysis

Cloud water samples from Whiteface Mountain, NY were used to develop a combined sampling and gas chromatography-mass spectrometric (GCMS) protocol for evaluating the complex mixture of highly polar organic compounds (HPOC) present in this atmospheric medium. Specific HPOC of interest were mono- and di keto-acids which are thought to originate from photochemical reactions of volatile unsaturated hydrocarbons from biogenic and manmade emissions and be a major fraction of atmospheric carbon. To measure HPOC mixtures and the individual keto-acids in cloud water, samples first must be derivatized for clean elution and measurement, and second, have low overall background of the target species as validated by GCMS analysis of field and laboratory blanks. Here, we discuss a dual derivatization method with PFBHA and BSTFA which targets only organic compounds that contain functional groups reacting with both reagents. The method also reduced potential contamination by minimizing the amount of sample processing from the field through the GCMS analysis steps. Once derivatized only gas chromatographic separation and selected ion monitoring (SIM) are needed to identify and quantify the polar organic compounds of interest. Concentrations of the detected total keto-acids in individual cloud water samples ranged from 27.8 to 329.3 ng mL-1 (ppb). Method detection limits for the individual HPOC ranged from 0.17 to 4.99 ng mL-1 and the quantification limits for the compounds ranged from 0.57 to 16.64 ng mL-1. The keto-acids were compared to the total organic carbon (TOC) results for the cloud water samples with concentrations of 0.607 to 3.350 mg L-1 (ppm). GCMS analysis of all samples and blanks indicated good control of the entire collection and analysis steps. Selected ion monitoring by GCMS of target keto-acids was essential for screening the complex organic carbon mixtures present at low ppb levels in cloud water. It was critical for ensuring high levels of quality assurance and quality control and for the correct identification and quantification of key marker compounds.Corrected proof of accepted manuscrip