Abstract  BACKGROUND: We previously demonstrated that apricot sulfurization workers are exposed to high concentrations of SO(2), subsequently causing asthma-like syndrome. This study investigated the effects of SO(2) exposure on serum TNF-alpha, IL-1beta, IL-6, IL-8, nitrite and nitrate levels to understand the mechanism of SO(2)-induced bronchoconstriction in asthma-like syndrome. METHODS: We measured the serum levels of the cytokines, direct nitrite, total nitrite and nitrate obtained from 40 volunteer workers after an hour of exposure to SO(2) and 23 healthy controls. RESULTS: The concentrations of the cytokines, direct nitrite, total nitrite and nitrate were significantly (p<0.0001) higher in the workers than in the controls. The mean serum concentrations of TNF-alpha, IL-1beta, IL-6, IL-8, direct nitrite, total nitrite and nitrate were 430.60+/-397.03 pg/ml, 436.67+/-316.31 pg/ml, 752.11+/-394.95 pg/ml, 262.12+/-287.99 pg/ml, 7.75+/-3.34 micromol/l, 115.72+/-48.78 micromol/l and 107.97+/-46.19 micromol/l in the workers, while they were 9.83+/-3.12 pg/ml, <5 pg/ml, 7.49+/-1.27 pg/ml, 9.38+/-1.99 pg/ml, 2.17+/-0.77 micromol/l, 59.91+/-7.56 micromol/l and 57.74+/-7.20 micromol/l in the controls, respectively. CONCLUSION: These results show that TNF-alpha, IL-1beta, IL-6, IL-8 and nitric oxide may play a role in the pathogenesis of bronchoconstriction in asthma-like syndrome due to the SO(2) exposure.

Abstract  #Information on amphibian responses to fire and fuel reduction practices is critically needed due to potential declines of species and the prevalence of new, more intensive fire management practices in North American forests. The goals of this review are to summarize the known and potential effects of fire and fuels management on amphibians and their aquatic habitats, and to identify information gaps to help direct future scientific research. Amphibians as a group are taxonomically and ecologically diverse; in turn, responses to fire and associated habitat alteration are expected to vary widely among species and among geographic regions. Available data suggest that amphibian responses to fire are spatially and temporally variable and incompletely understood. Much of the limited research has addressed short-term (1û3 years) effects of prescribed fire on terrestrial life stages of amphibians in the southeastern United States. Information on the long-term negative effects of fire on amphibians and the importance of fire for maintaining amphibian communities is sparse for the majority of taxa in North America. Given the size and severity of recent wildland fires and the national effort to reduce fuels on federal lands, future studies are needed to examine the effects of these landscape disturbances on amphibians. We encourage studies to address population-level responses of amphibians to fire by examining how different life stages are affected by changes in aquatic, riparian, and upland habitats. Research designs need to be credible and provide information that is relevant for fire managers and those responsible for assessing the potential effects of various fuel reduction alternatives on rare, sensitive, and endangered amphibian species.

Abstract  Equilibrium modeling predicts that atmospheric sea salt can partition gas-phase HNO(3) to solid- or aqueous-phase NaNO(3). One month of semi-continuous and simultaneous measurements of particulate chloride and nitrate and gaseous HCl and HNO(3) concentrations were made in the Tampa, Florida, as part of the Bay Region Atmospheric Chemistry Experiment (BRACE). Tampa's proximity to coastal and bay waters enriches its atmosphere with sea salt. To help explain and interpret the observed time-dependent concentration and gas-to-particle phase partitioning behavior for the NaCl HNO(3) reaction, we applied the Aerosol Inorganics Model III (AIM) to the measurement data. Good agreement between model predictions and observations was found. Measurement and modeling results suggested that coarse-mode sea salt particles from the Atlantic Ocean arrived in the morning at the monitoring site when relative humidity (RH) was high and the nature of the equilibrium least favored the outgassing of HCl from the particles. As the RH dropped in the afternoon, the equilibrium favored outgassing of HCl and the particulate nitrate concentration increased even as the concentration of coarse particles decreased. This effect was tied to the change in the ratio of nitrate to chloride activity coefficients gamma(-)(NO3) /gamma(-)(Cl) with RH. AIM simulations indicated that this ratio approached unity at high RH but could take on small values (similar to 0.05) at the lowest RH observed here. Thus, the particle phase slightly favored nitrate over chloride at high RH and greatly favored it at lower RH. Modeling revealed how diurnal changes in RH can rapidly shift HNO(3) concentrations from gas- to particle-phase and thus affect the distance over which nitrogen is transported. (c) 2007 Elsevier Ltd. All rights reserved.

Abstract  A PZT niobium-doped material (PZTN) was developed from precursor powders obtained by spray drying of water solution of Zr and Pb nitrates, Ti isopropoxide and Nb-ammonium complex. The thermo-oxidative process as well as the phase evolution were analysed. The morphology of powders was investigated as a function of the spray-drying conditions. The stoichiometry of the systems was checked at each stage of the process and no fluctuation was detected. The obtained powders had a spherical, hollow and porous structure and were transformed into a pure perovskite phase at 550 °C. The samples, sintered at 1100 °C for 2 h in air showed 98% relative density at densification temperature of 100 °C lower than following the conventional mixed oxide route. The green and final densities were improved by introducing a grinding step and high pressure cold isostatic consolidation. Some sintered samples were fully densified by hot isostatic pressing (1100 °C, 300 bars) post-treatment, obtaining pore free structures. The electrical characterisation showed comparable or better properties than those obtained with the related oxide method. (English)

Abstract  Twenty-two high-elevation lakes (>3000 in) in Rocky Mountain National Park and Indian Peaks Wilderness Area, Colorado, were surveyed during summer 1998 to explore relationships among benthic invertebrates, water chemistry (particularly nitrate concentrations), and other environmental variables. Water samples were collected from the deepest portion of each lake and analyzed for ions and other water chemistry parameters. Benthic invertebrates were collected front the littoral zone using both a sweep net and Hess sampler. Physical and geographical measurements were derived from maps. Relationships among benthic invertebrate assemblages and environmental variables were examined using canonical correspondence analysis, and the importance of sampling methodology and taxonomic resolution on these relationships was evaluated.

Choice of sampling methodology strongly influenced the outcome of statistical analyses, whereas taxonomic resolution did not. Presence/absence of benthic invertebrate taxa among the study lakes was best explained by elevation and presence of fish. Relative abundance and density of benthic invertebrate taxa were more strongly influenced by sampling date and water chemistry. Nitrate (NO3-) concentration, potentially on the rise due to regional nitrogen deposition, was unrelated to benthic invertebrate distribution regardless of sampling method or taxonomic resolution.

Abstract  We use the fractional aerosol optical depth (AOD) values derived from Multiangle Imaging Spectroradiometer (MISR) aerosol component measurements, along with aerosol transport model constraints, to estimate ground-level concentrations of fine particulate matter (PM2.5) mass and its major constituents in the continental United States. Regression models using fractional AODs predict PM2.5 mass and sulfate (SO4) concentrations in both the eastern and western United States, and nitrate (NO3) concentrations in the western United States reasonably well, compared with the available ground-level U.S. Environment Protection Agency (EPA) measurements. These models show substantially improved predictive power when compared with similar models using total-column AOD as a single predictor, especially in the western United States. The relative contributions of the MISR aerosol components in these regression models are used to estimate size distributions of EPA PM2.5 species. This method captures the overall shapes of the size distributions of PM2.5 mass and SO4 particles in the east and west, and NO3 particles in the west. However, the estimated PM2.5 and SO4 mode diameters are smaller than those previously reported by monitoring studies conducted at ground level. This is likely due to the satellite sampling bias caused by the inability to retrieve aerosols through cloud cover, and the impact of particle hygroscopicity on measured particle size distributions at ground level.

Abstract  The primary emission source contributions to fine organic carbon (OC) and fine particulate matter (PM2.5) mass concentrations on a daily basis in Atlanta, GA, are quantified for a summer (July 3 to August 4, 2001) and a winter (January 2-31, 2002) month. Thirty-one organic compounds in PM2.5 were identified and quantified by gas chromatography/mass spectrometry. These organic tracers, along with elemental carbon, aluminum, and silicon, were used in a chemical mass balance (CMB) receptor model. CMB source apportionment results revealed that major contributors to identified fine OC concentrations include meat cooking (7-68%; average: 36%), gasoline exhaust (7-45%; average: 21%), and diesel exhaust (6-41%; average: 20%) for the summer month, and wood combustion (0-77%; average: 50%); gasoline exhaust (14-69%; average: 33%), meat cooking (1-14%; average: 5%), and diesel exhaust (0-13%; average: 4%) for the winter month. Primary sources, as well as secondary ions, including sulfate, nitrate, and ammonium, accounted for 86 +/- 13% and 112 +/- 15% of the measured PM2.5 mass in summer and winter, respectively.

Abstract  Objective: It is still unknown whether specific components in fine particles are associated with heart rate variability (HRV) reduction. Methods: We recruited 46 patients with or at risk for cardiovascular diseases to measure 24-hour HRV by ambulatory electrocardiographic monitoring. Fixed-site air-monitoring stations were used to represent participants' exposures to particles with aerodynamic diameters less than 10 ?m (PM10) and 2.5 ?m (PM2.5), and particulate components of sulfate, nitrate, organic carbon (OC) and elemental carbon, and gaseous pollutants. Results: We found that HRV reduction was associated with sulfate, OC, and PM2. 5 but not with the other five pollutants in single-pollutant models. Sulfate was found to remain in significant association with HRV reduction adjusting for OC and PM2.5 in three-pollutant models. Conclusions: Exposures to sulfate and OC in PM2.5were associated with HRV reduction in patients with or at risk for cardiovascular diseases.

Abstract  This study is an attempt to quantify the relation between changes in NOx emissions and nitric acid (HNO3) in the northeastern USA. From this relation, and previous work relating NOx emission changes and wet NO3- deposition, we can estimate how changing NOx emissions may impact total (wet + dry) measured nitrogen (N) deposition.

Electric utility emissions account for 1/4, and vehicle emissions account for over 1/2 of the total NOx emissions in the eastern USA. Canadian NOx emissions from the seven easternmost provinces (Manitoba and east) represent less than 10% (1.2 teragrams (Tg) NOx) of the NOx emissions compared with those from the eastern USA. Emissions from eastern Canada are dominated by vehicle NOx emissions, which account for 2/3 of the total NOx emissions from eastern Canada.

Data from the EPA National Emissions Inventory show, for the period 1991-2001, that nitrogen oxide (NOx) emissions in the eastern USA have declined by 17% to from 16.1 to 13.1 Tg. Large declines in vehicle emissions in 2001 may be questionable. If 2001 data are excluded the decline in total NOx is only 7%. A recent assessment of EPAs emissions estimates suggest that vehicle NOx emissions may be underestimated, and total NOx emissions reductions may be less than what is reported by the EPA.

The CASTNet (Clean Air Status and Trends Network) measurements of N dry deposition include HNO3, particulate NO3- and NH4+. The dominant N dry deposition product measured is HNO3, which represents 80% of measured N dry deposition for the sites used in this study. Amounts of NH3, NO2, organic nitrate and PAN dry deposition are not measured by CASTNet. The NH3 and NO2 deposition are probably significant, and may be major N dry deposition components in some areas.

Random coefficient models with total NOx emissions as the independent variable, and HNO3 concentrations as the dependent variable, show that reducing total NOx emissions by 50% should reduce HNO3 concentrations by 36%. The average efficiency (the ratio of % change in HNO3 to % change in NOx emissions) is 72%. Random coefficient models with non-vehicle NOx emissions as the independent variable, and HNO3 concentrations as the dependent variable, show a 50% decline in non-vehicle NOx emissions (which is a 23% decline in total NOx emissions) should reduce HNO3 by 17-20%. The average efficiency in this case is 81 %. Because non-vehicle NOx emissions data are more reliable than vehicle NOx emissions, non-vehicle NOx models are likely more accurate than the total NOx models.

Abstract  Nitrate (NO3) and other nutrients discharged by the Mississippi River are suspected of causing a zone of depleted dissolved oxygen (hypoxic zone) in the Gulf of Mexico each summer. The hypoxic zone may have an adverse affect on aquatic life and commercial fisheries. The amount of NO3 delivered by the Mississippi River to the Gulf of Mexico is well documented, but the relative contributions of different sources of NO3, and the magnitude of subsequent in-stream transformations of NO3, are not well understood. Forty-two water samples collected in 1997 and 1998 at eight stations located either on the Mississippi River or its major tributaries were analysed for NO3, total nitrogen (N), atrazine, chloride concentrations and NO3 stable isotopes (delta N-15, delta O-18). These data are used to assess the magnitude and nature of in-stream N transformation and to determine if the delta N-15 and delta O-18 of NO3 provide information about NO3 sources and transformation processes in a large river system (drainage area similar to2 900 000 km(2)) that would otherwise be unavailable using concentration and discharge data alone.

Results from 42 samples indicate that the delta N-15 and delta O-18 ratios between sites on the Mississippi River and its tributaries are somewhat distinctive, and vary with season and discharge rate. Of particular interest are two nearly Lagrangian sample sets, in which samples from the Mississippi River at St Francisville, LA, are compared with samples collected from the Ohio River at Grand Chain, II, and the Mississippi River at Thebes, IL. In both Lagrangian sets, mass-balance calculations indicate only a small amount of in-stream N loss. The stable isotope data from the samples suggest that in-stream N assimilation and not denitrification accounts for most of the N loss in the lower Mississippi River during the spring and early summer months.

Abstract  Nanosilver has well-known antibacterial properties, and is widely used in daily life as various medical and general products. In comparison with silver ion, there is serious lacking of information concerning the biological effects of nanoAg. In this study, we observed the cytotoxic effect of nanoAg in HeLa cells. The nanoAg-induced cytotoxicity was lower than that of AgNO3, used as a silver ion source. Apoptosis evaluated by flowcytometric analysis was associated with this cell death. Further, the expressions of ho-1 and mt-2A, well-known oxidative stress-related genes, were up-regulated by nanoAg treatment. Our results showed that nanoAg possesses the potential for cytotoxicity, therefore, in the case of exposure at high concentrations, we should consider to protect from nanoAg-induced toxicity.

Abstract  The influence of N pulses in the form of experimental additions of HNO3 at two times ambient and (NH4)(2)SO4 at two and four times ambient on the herbaceous and woody understory plants in three Adirondack Mountain hardwood forests was evaluated. Addition of (NH4)(2)SO4 decreased cover of dominant herbs and woody seedlings at Woods Lake, a site in the western Adirondacks. Tissue N concentrations of combined herbs and ferns at Woods Lake increased with addition of NH4+ at both levels (9% at two times ambient; 13% at four times ambient) and increased with all three N treatments at Huntington Forest, a central Adirondack site (14% with NO3- and NH4+ at two times ambient; 22% with NH4+ at four times ambient). Seedlings of American beech (Fagus grandifolia Ehrh.) increased foliar N concentration 7-8% with addition of NH4+ treatments at Huntington Forest, but did nor respond to N addition at Woods Lake and Pancake Hall Creek, a western Adirondack site. In general, greatest plant nutrient response to N addition occurred at Huntington Forest, where atmospheric inputs of N are lower than at Woods Lake and Pancake Hall Creek.

Abstract  The size and composition of ambient airborne particulate matter is reported for winter conditions at five locations in (or near) the San Joaquin Valley in central California. Two distinct types of airborne particles were identified based on diurnal patterns and size distribution similarity: hygroscopic sulfate/ammonium/nitrate particles and less hygroscopic particles composed of mostly organic carbon with smaller amounts of elemental carbon. Day-time PM10 concentrations for sulfate/ammonium/nitrate particles were measured to be 10.1 μg m-3, 28.3 μg m-3, and 52.8 μg m-3 at Sacramento, Modesto and Bakersfield, California, respectively. Nighttime concentrations were 10-30% lower, suggesting that these particles are dominated by secondary production. Simulation of the data with a box model suggests that these particles were formed by the condensation of ammonia and nitric acid onto background or primary sulfate particles. These hygroscopic particles had a mass distribution peak in the accumulation mode (0.56-1.0 μm) at all times. Daytime PM10 carbon particle concentrations were measured to be 9.5 μg m-3, 15.1 μg m-3, and 16.2 μg m-3 at Sacramento, Modesto, and Bakersfield, respectively. Corresponding nighttime concentrations were 200-300% higher, suggesting that these particles are dominated by primary emissions. The peak in the carbon particle mass distribution varied between 0.2-1.0 μm. Carbon particles emitted directly from combustion sources typically have a mass distribution peak diameter between 0.1-0.32 μm. Box model calculations suggest that the formation of secondary organic aerosol is negligible under cool winter conditions, and that the observed shift in the carbon particle mass distribution results from coagulation in the heavily polluted concentrations experienced during the current study. The analysis suggests that carbon particles and sulfate/ammonium/nitrate particles exist separately in the atmosphere of the San Joaquin Valley until coagulation mixes them in the accumulation mode.

Abstract  The San Joaquin Valley (SJV) in California has one of the most severe particulate air quality problems in the United States during the winter season. In the current study, measurements of particulate matter (PM) smaller than 10 μm in aerodynamic diameter (PM10), fine particles (PM1.8), and ultrafine particles (PM0.1) made during the period December 16, 2000-February 3, 2001, at six locations near or within the SJV are discussed: Bodega Bay, Davis, Sacramento, Modesto, Bakersfield, and Sequoia National Park. Airborne PM1.8 concentrations at the most heavily polluted site (Bakersfield) increased from 20 to 172 μg/m3 during the period December 16, 2000-January 7, 2001. The majority of the fine particle mass was ammonium nitrate driven by an excess of gas-phase ammonia. Peak PM0.1 concentrations (8-12 hr average) were ∼2.4 μg/m3 measured at night in Sacramento and Bakersfield. Ultrafine particle concentrations were distinctly diurnal, with daytime concentrations ∼50% lower than nighttime concentrations. PM0.1 concentrations did not accumulate during the multiweek stagnation period; rather, PM0.1 mass decreased at Bakersfield as PM1.8 mass was increasing. The majority of the ultrafine particle mass was associated with carbonaceous material. The high concentrations of ultrafine particles in the SJV pose a potential serious public health threat that should be addressed.

Abstract  HEEP COPYRIGHT: BIOL ABS. The photosynthetic activity of the blue-green algae studied (Lyngbya sp., Anabaena flos-aquae, Oscillatoria sp., Schizothrix sp., Synechococcus cedrorum, Calothrix anomala, Fischerella muscicola, Cylindrospermum sp., Scenedesmus quadricauda, Ulothrix fimbriata, Chlamydomonas reinhardtii, Ankistrodesmus falcatus and Gloeocystis versiculosa) and was inhibited by 0.1 mM bisulfite. Other algae generally showed little or no inhibition; this group of resistant species included: 14 green algae, 2 yellow algae, a red alga and Euglena gracilis. Similarly, the 8 genera of blue green algae were consistently sensitive to 1 mM nitrite.

Abstract  At the global scale, among all N (nitrogen) species in the atmosphere and their deposition on to terrestrial vegetation and other receptors, NH3 (ammonia) is considered to be the foremost. The major sources for atmospheric NH3 are agricultural activities and animal feedlot operations, followed by biomass burning (including forest fires) and to a lesser extent fossil fuel combustion. Close to its sources, acute exposures to NH3 can result in visible foliar injury on vegetation. NH3 is deposited rapidly within the first 4û5 km from its source. However, NH3 is also converted in the atmosphere to fine particle NH4+ (ammonium) aerosols that are a regional scale problem. Much of our current knowledge of the effects of NH3 on higher plants is predominantly derived from studies conducted in Europe. Adverse effects on vegetation occur when the rate of foliar uptake of NH3 is greater than the rate and capacity for in vivo detoxification by the plants. Most to least sensitive plant species to NH3 are native vegetation > forests > agricultural crops. There are also a number of studies on N deposition and lichens, mosses and green algae. Direct cause and effect relationships in most of those cases (exceptions being those locations very close to point sources) are confounded by other environmental factors, particularly changes in the ambient SO2 (sulfur dioxide) concentrations. In addition to direct foliar injury, adverse effects of NH3 on higher plants include alterations in: growth and productivity, tissue content of nutrients and toxic elements, drought and frost tolerance, responses to insect pests and disease causing microorganisms (pathogens), development of beneficial root symbiotic or mycorrhizal associations and inter species competition or biodiversity. In all these cases, the joint effects of NH3 with other air pollutants such as all-pervasive O3 or increasing CO2 concentrations are poorly understood. While NH3 uptake in higher plants occurs through the shoots, NH4+ uptake occurs through the shoots, roots and through both pathways. However, NH4+ is immobile in the soil and is converted to NO3- (nitrate). In agricultural systems, additions of NO3- to the soil (initially as NH3 or NH4+) and the consequent increases in the emissions of N2O (nitrous oxide, a greenhouse gas) and leaching of NO3- into the ground and surface waters are of major environmental concern. At the ecosystem level NH3 deposition cannot be viewed alone, but in the context of total N deposition. There are a number of forest ecosystems in North America that have been subjected to N saturation and the consequent negative effects. There are also heathlands and other plant communities in Europe that have been subjected to N-induced alterations. Regulatory mitigative approaches to these problems include the use of N saturation data or the concept of critical loads. Current information suggests that a critical load of 5û10 kg ha-1 year-1 of total N deposition (both dry and wet deposition combined of all atmospheric N species) would protect the most vulnerable terrestrial ecosystems (heaths, bogs, cryptogams) and values of 10û20 kg ha-1 year-1 would protect forests, depending on soil conditions. However, to derive the best analysis, the critical load concept should be coupled to the results and consequences of N saturation.

Abstract  #311 chemicals were tested under code, for mutagenicity, in Salmonella typhimurium; 35 of the chemicals were tested more than once in the same or different laboratories. The tests were conducted using a preincubation protocol in the absence of exogenous metabolic activation, and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters. Some of the volatile chemicals were also tested in desiccators. A total of 120 chemicals were mutagenic or weakly mutagenic, 3 were judged questionable, and 172 were non-mutagenic. The remaining 16 chemicals produced different responses in the two or three laboratories in which they were tested. The results and data from these tests are presented.

Abstract  To understand the nocturnal sink of NOx in the outflow from the Asian source area, simultaneous observations of NO3, N2O5, and related compounds were conducted utilizing an instrument based on laser-induced fluorescence at Izu-Oshima Island, Japan, during June 2004. Consequently, significant levels of NO3 and N2O5 were successfully observed, particularly in the polluted air mass originating from Tokyo. This observation concurred with the equilibrium among NO3, NO2, and N2O5 gases. As a result of steady-state analysis, nocturnal NO, losses were evaluated as 1.8 and 0.2 ppbv night(-1) for polluted and maritime air, respectively. It was confirmed that the nocturnal NOx sink during the observation was promoted by the NO3 loss by VOC. DMS is significant for nocturnal loss of NOx over the sea. (c) 2006 Elsevier Ltd. All rights reserved.

Abstract  In this study, we present similar to1 yr (October 1998-September 1999) of 12-hour mean ammonia (NH3), ammonium (NH4+), hydrochloric acid (MCl), chloride (Cl-), nitrate (NO3-). nitric acid (HNO3). nitrous acid (HONO). Sulfate (SO42-), and sulfur dioxide (SO2) concentrations measured at an agricultural site in North Carolinas Coastal Plain region. Mean gas concentrations were 0.46, 1.21, 0.54, 5.55, and 4.15 mug m(-3) for HCl, HNO3, HONO, NH3, and SO2, respectively. Mean aerosol concentrations were 1.44, 1.23, 0.08, and 3.37 mug m(-3) for NH4+ NO3-, Cl-, and SO24-. respectively. Ammonia. NH4+, HNO3, and SO42- exhibit higher concentrations during the summer. awhile higher SO, concentrations occur during winter. A meteorology-based multivariate regression model using temperature, wind speed, and wind direction explains 76% of the variation in 12-hour mean NH3 concentrations (n = 601). Ammonia concentration increases exponentially with temperature. which explains the majority of variation (54%) in 12-hour mean NH3 concentrations. Dependence of NH3 concentration on wind direction suggests a local Source influence. Ammonia accounts for >70% of NHx (NHx = NH3 + NH4+) during all seasons. Ammonium nitrate and sulfate aerosol formation does not appear to be NH3 limited. Sulfate is primarily associated ammonium sulfate, rather than bisulfate, except during the winter when the ratio of NO3--NH4- is similar to0.66. The annual average NO3-NH4- ratio is similar to0.25. (C) 2002 Published by Elsevier Science Ltd.

Abstract  Nitrous acid, HONO, is a source of OH radicals in the polluted atmosphere. Although the atmospheric chemistry of HONO is qualitatively understood, not much quantitative information exists. The magnitude of the OH production by HONO photolysis depends on the spectrum of its absorption cross sections; therefore the knowledge of 'delta'HONO(gamma) is essential. The spectrum of the differential cross sections 'delta'HONO(gamma) is needed to detect HONO in the atmosphere by differential optical absorption spectroscopy (DOAS). Here we present measurements of the HONO UV-visible absorption cross sections with a spectral resolution better than 0.1 nm and a high signal-to-noise ratio. The maximum value of the absorption cross sections is sHONO (354 nm) = (5.19 +/- 0.26) Î 10-19 cm2 and agrees well with literature data. Nevertheless, calculations based on data from this work and on literature data reveal that an uncertainty of ~15% remains for the HONO photolysis rates. The new sHONO(?) has been employed in DOAS measurements in Milan, Italy.

Abstract  Six-month-old Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings were grown at three N concentrations and with controlled root temperatures. Measurements of root respiration were conducted on undisturbed root systems by passing humidified air with 1000 Ál l-1 CO2 through root boxes onto an infrared gas analyzer. The objective was to understand the effects of N on soil respiration by examining total root respiration rate per seedling, specific root respiration rate g-1 root dry wt, and root dry wt after N fertilization. Total respiration rates of seedlings grown at 50 mg l-1 N concentration were significantly higher than those grown at 10 mg l-1 or 200 mg l-1 N concentration. Seedlings grown at N concentration of 200 mg l-1 had significantly smaller roots than those grown at the two lower N concentrations. The specific respiration rate increased as N concentration was increased from 10 to 50 mg l-1 N concentration, but remained constant as N was further increased from 50 to 200 mg l-1. The increase of total respiration rate with the increase in N concentration from 10 to 50 mg l-1 was attributed to the increase in specific respiration, whereas the subsequent decrease in total respiration with the increase in N concentration from 50 to 200 mg l-1 was attributed to the decrease in root dry wt. The depression of soil respiration after the addition of N fertilizers to relatively fertile soil may be explained by reduced root and mycorrhizal mycelial growth.

Abstract  The objective of this study was to determine if prior exposure of rat hearts to S-nitrosocysteine (CysNO) was able to provide protection against reperfusion injury. We probed NO release using the extracellular NO scavenger oxyhemoglobin (oxyHb), and we examined the involvement of the amino acid transport system L (L-AT), a known transporter of CysNO, using the L-AT competitor, l-leucine (L-Leu). Isolated (9- to 12-week-old Wistar male) rat hearts (six to eight per group) were perfused with CysNO (10 ÁM) for 30 min with or without the L-AT competitor L-Leu (1 mM) before 30 min of ischemia. Cardiac function was assessed before, during, and after treatment and during 120 min of reperfusion after ischemia. Functional recovery (rateûpressure product) was significantly improved in the CysNO group compared to hearts in the CysNO + L-Leu group and the control group (p < 0.05). Necrosis, measured by triphenyltetrazolium chloride staining, was significantly reduced in CysNO hearts (p < 0.05) and this improvement was reversed by L-Leu. The NO scavenger oxyHb (20 ÁM) was perfused either concomitant with CysNO or just before ischemia. In neither case did oxyHb affect the cardioprotection afforded by CysNO. OxyHb alone, given in either time window, did not alter the course of ischemiaûreperfusion injury. When nitrite was used in place of CysNO, no protective effects were observed. Perfusion with CysNO increased tissue S-nitrosothiol (RSNO) levels from an unmeasurable background to a value of about 15.7 ± 4.1 pmol RSNO/mg protein, as measured by triiodide-based chemiluminescence in the presence and absence of mercury(II) chloride. In the presence of l-Leu, this value dropped to 0.4 ± 0.3 pmol RSNO/mg protein. This study demonstrates that exposure to CysNO before ischemia increases tissue S-nitrosothiol levels, improves postischemic contractile dysfunction, and attenuates necrosis. The mechanism of cardioprotection requires the uptake of CysNO via the L-AT and does not seem to involve NO release either during CysNO exposure or during ischemia. This suggests that the protective effects of CysNO are mediated through the posttranslational modification of cellular proteins through an NO-independent transnitrosation mechanism.

Abstract  Combined p.o. administration of sodium nitrite and dimethylamine or methylbenzylamine to male mice produced acute synergistic toxicity, as evidenced by relative weight loss, mortality, and liver necrosis. Similar results were obtained when p.o. dosage of dimethylamine was followed by single administration of sodium nitrite at intervals up to 3 hr; toxicity was, however, markedly reduced when sodium nitrite was administered prior to dimethylamine. The incidence of mortality and liver necrosis was dependent on the time interval separating successive administrations of sodium nitrite and dimethylamine.