[en] The Consultant's meeting on ''Operational Aspects of the Global Network - Isotopes in Precipitation'' was organized by the International Atomic Energy Agency (IAEA) in co-operation with the World Meteorological Organization (WMO), the Past Global Changes Project (PAGES) of the International Geosphere-Biosphere Programme (IGBP), the World Health Organization (WHO) and the International Association of Hydrological Sciences (IAHS). It was agreed to transfer the responsibility of running the GNIP and the collection of isotope data in precipitation to a Steering Committee, which will consist of representatives of the following organizations: IAEA, WMO, IGBP-PAGES, WHO, UNESCO and IAHS. The responsibilities of the International Atomic Energy Agency (IAEA) in the Steering Committee are as follows: Co-ordination of the sample analysis: Arrangements for and participation in the measuring programme. Monitoring analytical aspects of sample collection, storage, etc. Arrangements for interlaboratory comparison exercises; collection of isotope and meteorological data, maintenance of the GNIP database and data distribution to interested users; promotion of full use and wider application of GNIP data in practical hydrological applications. Figs, tabs

[en] Aerosol particles from the tropical rain forest and from savannah biomass burning were collected in several experiments in the Amazon Basin. The size distribution of atmospheric trace elements was measured under both background and biomass burning conditions. Sampling from aircraft was performed over a large area of the Amazon Basin in August/September 1991. The aerosol mass concentration, black carbon and trace element concentrations were determined for fine and coarse aerosol particles. Particle induced X ray emission (PIXE) was used to measure the concentrations of up to 22 elements: Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr and Pb. During the dry season, when most of the biomass burning occurs, the concentration of inhalable particles exceeds 300 μg/m³ in regions far from the direct influence of emissions from biomass burning. Large amounts of fine particles are injected into the atmosphere, where they can travel over long distances. These particles are rich in K, P, S, Ca, Mg, Cl, Si, Zn, Rb, Sr, Zr and other trace elements. The emissions of trace elements and heavy metals into the global atmosphere owing to biomass burning are very significant, but are currently not considered in global atmospheric heavy metal inventories. Several essential nutrients, such as P, K, S and others, are transported into the atmosphere as a result of biomass burning processes. Most of the particles are water soluble and can be active as cloud condensation nuclei, with the potential to change the cloud formation mechanisms in the Amazon Basin and other regions of the planet. 22 refs, 5 figs, 1 tab

[en] Short communication. 2 figs

[en] Many recent studies of atmospheric trace gases have included analyses of stable isotope compositions of key elements. One such example is the use of ¹³CH₄ in studies of atmospheric methane and its sources and sinks. δ¹³CH₄ measurements of background methane and its sources are used along with companion data of fluxes to help determine relative source strengths. A mass-weighted average composition of all sources should equal the mean δ¹³C of atmospheric methane corrected for any isotope fractionation effects in methane sink reactions. The principal sink for methane in the atmosphere is from its reaction with OH radicals. At NCAR the authors measured the carbon kinetic isotope effect for this reaction and have reported a value of 1.0054 ± 0.0009 for the ratio of the rate coefficients k₁₂/k₁₃. This value improves on earlier determinations make by the authors and others. A discussion of experimental techniques and difficulties is presented here. A mass-weighted hydrogen isotope balance similar to that described above for carbon could also be very useful in constraining the methane budget. They are in the process of determining the KCH₄/KCH₃D KIE value for reaction with OH at temperatures which can be found in the troposphere

[en] Photolysis of ⁴⁸O₃ in a non-scrambled mixture of ³²O₂ and ³⁶O₂ gives not only OO*O* and O*OO* but also O*OO, OO*O and O*O*O* arising from rapid exchange. The question as to whether O adds (i) end-on, (ii) in the middle or (iii) via D_3h intermediate, has been answered in favor of (i) using the ratios OO*O*/O*OO* and O*OO/OO*O as indicators. Microwave spectroscopy has been used to analyze the reaction mixtures

[en] The formula for calculating radon short-lived daughter concentrations in measured air by means of total alpha-counting and alpha-spectrometric methods is detailed according to the boundary conditions to solve Bateman equation from radioactive decay law. The computer programs have been written. Two procedure errors in references are pointed out. Some coefficients of published procedures are completed and corrected, and corresponding formula are listed out in SI system. For thoron daughters, it also may be dealt with the same formula

[en] A proton microbeam with 2 μm lateral resolution has been established at the Accelerator Laboratory of Fudan University and was used to study gold-bearing submicroscopic gold minerals and gold inclusions. Au is found to be closely related to Fe, S and especially to As in the mineral sample from Jinya, Guangxi province

[en] A tracer technique has been developed to quantify in-cloud oxidation of SO₂. SO₄ in cloud droplets originates from (1) scavenging of aerosols, and (2) absorption of SO₂ followed by oxidation, primarily by H₂O₂. If a tracer element M is present as particulate with no gas-phase component, it can be shown that (SO_4in) = [(SO₄/M)_cw(α/β)(SO₄/M)_aa](M)_cw where SO_4in = SO4 formed from in situ oxidation, α and β are the respective scavenging efficiencies of SO₄ and M, cw and aa represent cloud water and aerosols, respectively. Measurements using Se as tracers at Whiteface Mountain, N.Y. yielded contributions of up to 50% from in situ oxidation. Arsenic was used as a tracer in one cloud event and yielded data in very good agreement with that of Se. Investigation on other trace elements is in progress. An accurate knowledge of in-cloud oxidation is essential in deciding the linearity/nonlinearity between regional SO₂ emissions and acid deposition, which is critical in designing a strategy to restrict regional SO₂ emissions to achieve goals in reducing acid deposition

[en] Short communication

[en] Short communication. 3 refs, 2 figs