Cytological studies on mosses from Papua New Guinea : 1., introduction and the family Orthotrichaceae.

Chromosome numbers with information on meiotic behaviour are recorded for the first time for the following taxa in the family Orthotrichaceae from Papua New Guinea - Desmotheca apiculata (Dozy & Molk.) Lindb. ex Card. n=6; Macromitrium incurvifolium (Hook. & Grev.) Schwaegr. n=9, M. longicaule C. Muell. n=6 (5+X/y), M. orthostichum Nees ex Schwaegr. n=7 (6+ X/y), M. salakanum C. Muell. n=9, M. similirete Bartr. n=9. M. streimannii Vitt n=9 (8+m); Schlotheimia emarginato-pilosa Herz. n=9 and S. macgregorii Broth. & Geh. n=11

Electrochemical polymerisation of phenol in aqueous solution on a Ta/PbO2 anode

This paper deals with the treatment of aqueous phenol solutions using an electrochemical technique. Phenol can be partly eliminated from aqueous solution by electrochemically initiated polymerisation. Galvanostatic electrolyses of phenol solutions at concentration up to 0.1 mol dm−3 were carried out on a Ta/PbO2 anode. The polymers formed are insoluble in acidic medium but soluble in alkaline. These polymers were filtered and then dissolved in aqueous solution of sodium hydroxide (1 mol dm−3). The polymers formed were quantified by total organic carbon (TOC) measurement. It was found that the conversion of phenol into polymers increases as a function of initial concentration, anodic current density, temperature, and solution pH. The percentage of phenol polymerised can reach 15%

A comparison of electrochemical degradation of phenol on boron doped diamond and lead dioxide anodes

This work compares two electrode materials used to mineralize phenol contained in waste waters. Two disks covered with either boron doped diamond (BDD) or PbO2 were used as anodes in a one compartment flow cell under the same hydrodynamic conditions. Efficiencies of galvanostatic electrolyses are compared on the basis of measurements of Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD). Galvanostatic electrolyses were monitored by analysis of phenol and of its oxidation derivatives to evaluate the operating time needed for complete elimination of toxic aromatics. The experimental current efficiency is close to the theoretical value for the BDD electrode. Other parameters being equal, phenol species disappeared at the same rate using the two electrode materials but the BDD anode showed better efficiency to eliminate TOC and COD. Moreover, during the electrolysis less intermediates are formed with BDD compared to PbO2 whatever the current density. A comparison of energy consumption is given based on the criterion of 99% removal of aromatic compounds

Predicted change in global secondary organic aerosol concentrations in response to future climate, emissions, and land use change

Copyright 2008 by the American Geophysical Union. 0148-0227/08/2007JD009092The sensitivity of secondary organic aerosol (SOA) concentration to changes in climate and emissions is investigated using a coupled global atmosphere-land model driven by the year 2100 IPCC A1B scenario predictions. The Community Atmosphere Model (CAM3) is updated with recent laboratory determined yields for SOA formation from monoterpene oxidation, isoprene photooxidation and aromatic photooxidation. Biogenic emissions of isoprene and monoterpenes are simulated interactively using the Model of Emissions of Gases and Aerosols (MEGAN2) within the Community Land Model (CLM3). The global mean SOA burden is predicted to increase by 36% in 2100, primarily the result of rising biogenic and anthropogenic emissions which independently increase the burden by 26% and 7%. The later includes enhanced biogenic SOA formation due to increased emissions of primary organic aerosol (5–25% increases in surface SOA concentrations in 2100). Climate change alone (via temperature, removal rates, and oxidative capacity) does not change the global mean SOA production, but the global burden increases by 6%. The global burden of anthropogenic SOA experiences proportionally more growth than biogenic SOA in 2100 from the net effect of climate and emissions (67% increase predicted). Projected anthropogenic land use change for 2100 (A2) is predicted to reduce the global SOA burden by 14%, largely the result of cropland expansion. South America is the largest global source region for SOA in the present day and 2100, but Asia experiences the largest relative growth in SOA production by 2100 because of the large predicted increases in Asian anthropogenic aromatic emissions. The projected decrease in global sulfur emissions implies that SOA will contribute a progressively larger fraction of the global aerosol burden

Northern Hemisphere Atmospheric Influence of the Solar Proton Events and Ground Level Enhancement in January 2005

Solar eruptions in early 2005 led substantial barrage of charged particles on the Earth's atmosphere during the January 16-21 period. Proton fluxes were greatly increased during these several days and led to the production ofHO(x)(H, OH, BO2)and NO(x)(N, NO, NO2), which then caused the destruction of ozone. We focus on the Northern polar region, where satellite measurements and simulations with the Whole Atmosphere Community Climate Model (WACCM3) showed large enhancements in mesospheric HO(x) and NO(x) constituents, and associated ozone reductions, due 10 these solar proton events (SPEs). The WACCM3 simulations show enhanced short-lived OH throughout the mesosphere in the 60-82.5degN latitude band due to the SPEs for most days in the Jan.16-2l,2005 period, in reasonable agreement with the Aura Microwave Limb Sounder (MLS) measurements. Mesospheric HO2 is also predicted to be increased by the SPEs, however, the modeled HO2 results are somewhat larger than the MLS measurements. These HO(x) enhancements led to huge predicted and MLS-measured ozone decreases of greater than 40% throughout most of the Northern polar mesosphere during the SPE period. Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) measurements of hydrogen peroxide (H2O2) show increases throughout the stratosphere with highest enhancements of about 60 ppt y in the lowermost mesosphere over the Jan. 16-18, 2005 period due to the solar protons. WACCM3 predictions indicate H2O2 enhancements over the same time period of more than twice that amount. Measurements of nitric acid (HNO3) by both MLS and MIPAS show an increase of about 1 ppbv above background levels in the upper stratosphere during January 16-29, 2005. WACCM3 simulations show only minuscule HNO3 changes in the upper stratosphere during this time period. However due to the small loss rates during winter, polar mesospheric enhancements of NO(x) are computed to be greater than 50 ppbv during the SPE period. Computed NO(x)increases, which were statistically significant at the 95% level, lasted about a month past the SPEs. The SCISAT-I Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) NO(x) measurements and MIPAS NO, measurements for the polar Northern Hemisphere are in reasonable agreement with these predictions. An extremely large ground level enhancement (GLE) occurred during the SPE period on January 20, 2005. We find that protons of energies 300 to 20,000 MeV, not normally included in our computations, led to enhanced lower stratospheric odd nitrogen concentrations of less than 0.1% as a result of this GLE

Short- and medium-term atmospheric constituent effects of very large solar proton events

International audienceSolar eruptions sometimes produce protons, which impact the Earth's atmosphere. These solar proton events (SPEs) generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and odd-nitrogen in the polar cap regions (>60° geomagnetic latitude). We have used the Whole Atmosphere Community Climate Model (WACCM3) to study the atmospheric impact of SPEs over the period 1963?2005. The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months after the events. We present the short- and medium-term (days to a few months) atmospheric influence of the four largest SPEs in the past 45 years (August 1972; October 1989; July 2000; and October?November 2003) as computed by WACCM3 and observed by satellite instruments. Polar mesospheric NOx (NO+NO2) increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs. Changes in HNO3, N2O5, ClONO2, HOCl, and ClO were indirectly caused by the very large SPEs in October?November 2003, were simulated by WACCM3, and previously measured by Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). WACCM3 output was also represented by sampling with the MIPAS averaging kernel for a more valid comparison. Although qualitatively similar, there are discrepancies between the model and measurement with WACCM3 predicted HNO3 and ClONO2 enhancements being smaller than measured and N2O5 enhancements being larger than measured. The HOCl enhancements were fairly similar in amounts and temporal variation in WACCM3 and MIPAS. WACCM3 simulated ClO decreases below 50 km, whereas MIPAS mainly observed increases, a very perplexing difference. Upper stratospheric and lower mesospheric NOx increased by over 10 ppbv and was transported during polar night down to the middle stratosphere in several weeks past the SPE. The WACCM3 simulations confirmed the SH HALOE observations of enhanced NOx in September 2000 as a result of the July 2000 SPE and the NH SAGE II observations of enhanced NO2 in March 1990 as a result of the October 1989 SPEs

Relationship between ecosystem productivity and photosynthetically-active radiation for northern peatlands

We analyzed the relationship between net ecosystem exchange of carbon dioxide (NEE) and irradiance (as photosynthetic photon flux density or PPFD), using published and unpublished data that have been collected during midgrowing season for carbon balance studies at seven peatlands in North America and Europe. NEE measurements included both eddy-correlation tower and clear, static chamber methods, which gave very similar results. Data were analyzed by site, as aggregated data sets by peatland type (bog, poor fen, rich fen, and all fens) and as a single aggregated data set for all peatlands. In all cases, a fit with a rectangular hyperbola (NEE = α PPFD Pmax/(α PPFD + Pmax) + R) better described the NEE-PPFD relationship than did a linear fit (NEE = β PPFD + R). Poor and rich fens generally had similar NEE-PPFD relationships, while bogs had lower respiration rates (R = −2.0μmol m−2s−1 for bogs and −2.7 μmol m−2s−1 for fens) and lower NEE at moderate and high light levels (Pmax = 5.2 μmol m−2s−1 for bogs and 10.8 μmol m−2s−1 for fens). As a single class, northern peatlands had much smaller ecosystem respiration (R = −2.4 μmol m−2s−1) and NEE rates (α = 0.020 and Pmax = 9.2μmol m−2s−1) than the upland ecosystems (closed canopy forest, grassland, and cropland) summarized by Ruimy et al. [1995]. Despite this low productivity, northern peatland soil carbon pools are generally 5–50 times larger than upland ecosystems because of slow rates of decomposition caused by litter quality and anaerobic, cold soils

Toward a chemical reanalysis in a coupled chemistry-climate model: an evaluation of MOPITT CO assimilation and its impact on tropospheric composition

We examine in detail a 1 year global reanalysis of carbon monoxide (CO) that is based on joint assimilation of conventional meteorological observations and Measurement of Pollution in The Troposphere (MOPITT) multispectral CO retrievals in the Community Earth System Model (CESM). Our focus is to assess the impact to the chemical system when CO distribution is constrained in a coupled full chemistry-climate model like CESM. To do this, we first evaluate the joint reanalysis (MOPITT Reanalysis) against four sets of independent observations and compare its performance against a reanalysis with no MOPITT assimilation (Control Run). We then investigate the CO burden and chemical response with the aid of tagged sectoral CO tracers. We estimate the total tropospheric CO burden in 2002 (from ensemble mean and spread) to be 371 ± 12% Tg for MOPITT Reanalysis and 291 ± 9% Tg for Control Run. Our multispecies analysis of this difference suggests that (a) direct emissions of CO and hydrocarbons are too low in the inventory used in this study and (b) chemical oxidation, transport, and deposition processes are not accurately and consistently represented in the model. Increases in CO led to net reduction of OH and subsequent longer lifetime of CH4 (Control Run: 8.7 years versus MOPITT Reanalysis: 9.3 years). Yet at the same time, this increase led to 5-10% enhancement of Northern Hemisphere O3 and overall photochemical activity via HOx recycling. Such nonlinear effects further complicate the attribution to uncertainties in direct emissions alone. This has implications to chemistry-climate modeling and inversion studies of longer-lived species