Investigation of the role of neutron transfer in the fusion of 32,34S with 197Au,208Pb using quasi-elastic scattering

Excitation functions for quasi-elastic scattering have been measured at backward angles for the systems 32,34S+197Au and 32,34S+208Pb for energies spanning the Coulomb barrier. Representative distributions, sensitive to the low energy part of the fusion barrier distribution, have been extracted from the data. For the fusion reactions of 32,34S with 197Au couplings related to the nuclear structure of 197Au appear to be dominant in shaping the low energy part of the barrier distibution. For the system 32S+208Pb the barrier distribution is broader and extends further to lower energies, than in the case of 34S+208Pb. This is consistent with the interpretation that the neutron pick-up channels are energetically more favoured in the 32S induced reaction and therefore couple more strongly to the relative motion. It may also be due to the increased collectivity of 32S, when compared with 34S.Comment: 11 pages, 5 figure

Tunable diode laser in-situ CH₄ measurements aboard the CARIBIC passenger aircraft: instrument performance assessment

A laser spectrometer for automated monthly measurements of methane (CH 4) mixing ratios aboard the CARIBIC passenger aircraft is presented. The instrument is based on a commercial Fast Greenhouse Gas Analyser (FGGA, Los Gatos Res.), which was adapted to meet the requirements imposed by unattended airborne operation. It was characterised in the laboratory with respect to instrument stability, precision, cross sensitivity to H2O, and accuracy. For airborne operation, a calibration strategy is described that utilises CH4 measurements obtained from flask samples taken during the same flights. The precision of airborne measurements is 2 ppb for 10 s averages. The accuracy at aircraft cruising altitude is 3.85 ppb. During aircraft ascent and descent, where no flask samples were obtained, instrumental drifts can be less accurately determined and the uncertainty is estimated to be 12.4 ppb. A linear humidity bias correction was applied to the CH4 measurements, which was most important in the lower troposphere. On average, the correction bias was around 6.5 ppb at an altitude of 2 km, and negligible at cruising flight level. Observations from 103 long-distance flights are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere (UT/LMS), with occasional crossing of the tropics on flights to southern Africa. These accurate data mark the largest UT/LMS in-situ CH4 dataset worldwide. An example of a tracer-tracer correlation study with ozone is given, highlighting the possibility for accurate cross-tropopause transport analyses. © Author(s) 2014

Analysis of Accurate 13C and 18O Isotope Measurements of CO2 in CARIBIC Aircraft Air Samples from the Tropical Troposphere, and the Upper Troposphere/Lowermost Stratosphere

The project CARIBIC (http://caribic-atmospheric.com) aims to study atmospheric chemistry and composition by regularly measuring many compounds and species in the free troposphere (FT) and the upper troposphere-lowermost stratosphere (UT/LMS) by using passenger aircraft. Here CO2 concentrations and highly accurate isotope results are presented together with supporting trace gas data. About 500 samples (CARIBIC-2, highest precision and accuracy delta13C(CO2) and delta18O(CO2) data) from June 2007 until March 2009, together with about 350 CARIBIC-1 samples (mostly delta13C(CO2) from flights between November 1999 and April 2002) give a fairly extensive, unique data set for the free troposphere and the UT/LMS region in the NH. To compare data from different years a de-trending is applied. In the UT/LMS region delta13C(CO2), delta18O(CO2) and CO2 are found to correlate well with stratospheric tracers; particularly N2O. These correlations are in good agreement with current understanding of the stratospheric circulation. Delta18O(CO2) appears to be a useful, hitherto unused, tracer of atmospheric transport in the UT/LMS region. By filtering out the LMS data (based on N2O distribution), the isotope variations for the free and upper troposphere are obtained. These show however little latitudinal gradient, if any, and are in good agreement with the data of selected NOAA stations in NH tropics. For many flights delta13C(CO2) correlates well with CO2 within a single flight covering long distances. Correlations for certain seasons are also good, demonstrating a large scale seasonal source/sink balance. The overall variability in detrended delta13C(CO2) and CO2 for CARIBIC-1 and CARIBIC-2 are similar. Furthermore, all trends for CARIBIC-1 and CARIBIC-2 basically agree with each other, which independently underscores our understanding of involved processes as well as the high quality of the measurement. Based on all correlations, we discuss that CO2 distribution in FT and UT region in the NH is mostly regulated by uplift and pole-wards transport of tropical air. The main reasons for variability of signals in FT and UT (which is larger for the high spatial resolution sampling during CARIBIC-2) is mixing of different tropospheric air masses affected by CO2 sources and sinks. The effect of stratospheric flux appears to be limited. All in all it is demonstrated that CARIBIC produced new important and reliable data sets for little explored regions of the atmosphere. The paper carefully documents these data, of which we hope that they will assist global scale modeling of 13C and especially 18O, which is linked to the hydrological cycle.JRC.D.3-Knowledge Transfer and Standards for Securit

The stable isotopic composition of molecular hydrogen in the tropopause region probed by the CARIBIC aircraft

More than 450 air samples that were collected in the upper troposphere – lower stratosphere (UTLS) region around the tropopause (TP) by the CARIBIC aircraft (Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container) have been analyzed 5 for molecular hydrogen (H2) mixing ratios (m(H2)) and H2 isotopic composition (deuterium content, D). More than 120 of the analysed samples consisted of air from the lowermost stratosphere (LMS). These show that m(H2) does not vary appreciably with O3-derived height above the thermal TP, whereas D does increase with height. The isotope 10 enrichment is caused by competing H2 production and destruction processes that enrich the stratospheric H2 reservoir in deuterium (D); the exact shapes of the profiles are mainly determined by mixing of stratospheric with tropospheric air. Tight negative correlations are found between D and the mixing ratios of methane (CH4) and nitrous oxide (N2O), as a result of the relatively long lifetimes of these three 15 species. The correlations are described by D [h] = −0.35 ·m(CH4)[ppb]+768 and D [h] = −1.90·m(N2O)[ppb]+745. These correlations are similar to previously published results and likely hold globally. Samples that were collected from the Indian subcontinent up to 40 N before, during and after the summer monsoon season show no significant seasonal change in m(H2), 20 but D is up to 15h lower in the July, August and September monsoon samples. This D lowering is correlated with m(CH4) increase. The significant correlation with m(CH4) and the absence of a perceptible m(H2) increase that accompanies the D lowering indicates that microbial production of very D-depleted H2 in the wet season may contribute to this phenomenon. 25 Some of the samples have very high m(H2) and very low D values, which indicates a pollution effect. Aircraft engine exhaust plumes are a suspected cause, since the effect mostly occurs in samples collected close to airports, but no similar signals are found in other chemical tracers to support this. The isotopic source signature of the H2 pollution seems to be on the low end of the signature for fossil fuel burning

Characterization and source regions of 51 high-CO events observed during Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) flights between south China and the Philippines, 2005-2008

Carbon monoxide (CO) and other atmospheric trace constituents were measured from onboard an Airbus 340-600 passenger aircraft in the upper troposphere (UT) between south China and the Philippines during Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) flights from May 2005 until March 2008. A total of 132 events having CO enhancements were observed in the UT over the region during the 81 CARIBIC flights from Frankfurt, Germany, to Manila, Philippines, with a stopover in Guangzhou, China. Among these, 51 high-CO events with enhancements more than 50 ppb above background were observed. For these events enhancements ranged from 52.7 to 221.3 ppb and persisted for 3 to 78 min (∼40 to 1200 km), indicating an influence of strong pollution from biomass/biofuel/fossil fuel burning on the trace gas composition of the UT. Back trajectory analysis shows that south China, the Indochinese Peninsula, and the Philippines/Indonesia are the main source regions of the high-CO events. The composition of air parcels originating from south China was found to be primarily influenced by anthropogenic urban/industrial emissions, while emissions from biomass/biofuel burning contributed substantially to CO enhancements from the Indochinese Peninsula. During the Philippines/Indonesia events, air parcel composition suggests contributions from both biomass/biofuel burning and urban/industrial sources. Long-range transport of air parcels from northeast Asia and India also contributed to CO enhancements in the UT over the region. The general features of regional influence, typical cases, and the contributions of biomass/biofuel burning and anthropogenic emissions are presented and discussed to characterize the air parcels during the observed high-CO events

Atmospheric CH4 in the first decade of the 21st century: Inverse modeling analysis using SCIAMACHY satellite retrievals and NOAA surface measurements

The causes of renewed growth in the atmospheric CH4 burden since 2007 are still poorly understood and subject of intensive scientific discussion. We present a reanalysis of global CH4 emissions during the 2000s, based on the TM5-4DVAR inverse modeling system. The model is optimized using high-accuracy surface observations from NOAA ESRL’s global air sampling network for 2000–2010 combined with retrievals of column-averaged CH4 mole fractions from SCIAMACHY onboard ENVISAT (starting 2003). Using climatological OH fields, derived global total emissions for 2007–2010 are 16–20 Tg CH4/yr higher compared to 2003–2005. Most of the inferred emission increase was located in the tropics (9–14 Tg CH4/yr) and mid-latitudes of the northern hemisphere (6–8 Tg CH4/yr), while no significant trend was derived for Arctic latitudes. The atmospheric increase can be attributed mainly to increased anthropogenic emissions, but the derived trend is significantly smaller than estimated in the EDGARv4.2 emission inventory. Superimposed on the increasing trend in anthropogenic CH4 emissions are significant inter-annual variations (IAV) of emissions from wetlands (up to 10 Tg CH4/yr), and biomass burning (up to 7 Tg CH4/yr). Sensitivity experiments, which investigated the impact of the SCIAMACHY observations (versus inversions using only surface observations), of the OH fields used, and of a priori emission inventories, resulted in differences in the detailed latitudinal attribution of CH4 emissions, but the IAV and trends aggregated over larger latitude bands were reasonably robust. All sensitivity experiments show similar performance against independent shipboard and airborne observations used for validation, except over Amazonia where satellite retrievals improved agreement with observations in the free troposphere.JRC.H.2-Air and Climat

Dinâmica do chumbo no lago do parque Ingá, Maringá, PR, Brasil

Este trabalho analisa a dinâmica do chumbo no lago do parque do Ingá, Maringá - PR. Mensalmente durante um ano foram coletadas amostras de água e sedimentos e o pH e temperatura medidos no ato da coleta. Nas amostras de água foi determinada a Demanda Química de Oxigênio (DQO) e a concentração total de Pb na água e sedimentos. A determinação da concentração Pb na água e sedimentos foi feita com a técnica da espectrometria da absorção atômica, modalidade chama. Os valores médios mensais encontrados, em intervalos e médias globais foram respectivamente: concentração de Pb na água, em ng.mL-1, não detectado (nd) - 55,56 e 19,23; Pb em sedimentos, em µg.g-1, 48,73 - 92,87 e 71,93; pH, 7,02 - 8,23 e 7,60; temperatura, em °C, 19,33 - 27,48 e 23,73; DQO, em mg.L-1, 13,33 - 30,11 e 23,54. Uma análise dos resultados das variáveis medidas, em nível de 5% de significância permitem concluir que a concentração de Pb na água é independente dos pontos de coleta (local), mas, dependente do período de amostragem (temporalidade) e nos sedimentos dependente dos dois parâmetros.<br>This work introduce the study of lead dynamic in the lake of Ingá Park, Maringá - PR. Monthly, during a year, samples of water and sediments were collected and pH and temperature measured. In the water samples were determined the chemical oxygen demand (COD) and the total lead concentration in water and sediment samples. The determination of lead concentration in water and sediments was performed with atomic absorption spectrometer - flame technique. The monthly mean values found, presented in intervals and global mean values, were respectively: lead concentration in water (ng.mL-1), non detected (nd) - 55.56 and 19.23; lead in sediments (µg.g-1), 48.73 - 92.87 and 71.93; pH, 7.02 - 8.23 and 7.60; temperature (ºC), 19.33 - 27.48 and 23.73; COD (mg.L-1), 13.33 - 30.11 and 23.54. A survey of the lead concentration results found permit to conclude, at 5% of significance, that the lead concentration in water was independent of the sampling point (local), but dependent of the sampling period (temporality) and in the sediment dependent of the two parameters