Short-Lived Trace Gases in the Surface Ocean and the Atmosphere

The two-way exchange of trace gases between the ocean and the atmosphere is important for both the chemistry and physics of the atmosphere and the biogeochemistry of the oceans, including the global cycling of elements. Here we review these exchanges and their importance for a range of gases whose lifetimes are generally short compared to the main greenhouse gases and which are, in most cases, more reactive than them. Gases considered include sulphur and related compounds, organohalogens, non-methane hydrocarbons, ozone, ammonia and related compounds, hydrogen and carbon monoxide. Finally, we stress the interactivity of the system, the importance of process understanding for modeling, the need for more extensive field measurements and their better seasonal coverage, the importance of inter-calibration exercises and finally the need to show the importance of air-sea exchanges for global cycling and how the field fits into the broader context of Earth System Science

Heavy metals contamination of soils surrounding waste deposits in Romania

Soils contamination with heavy metals is one of the most severe aspects of environmental pollution in Romania, independently of the origin sources (domestic or industrial activities) or type of disposal (organised landfill or hazardous deposits)[l-2]. This fact is the consequence of the poor state of the existing waste deposits in Romania and of the significant costs involved by the establishing of a new landfill according with the international regulations. The present study is trying to emphasise the contamination of soils surrounding different categories of waste deposits (sewage sludge ponds, domestic and industrial waste landfills, hillocks, sterile deposits) from various regions of Romania. Some case studies show a special interest being localise in a protected area (Iron Gates Natural Park). In order to quantify the concentration of metals like Cd, Cr, Cu, Pb, Zn, Ni, Mo in soil samples, analysis were performed using Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). Romanian standards were used as reference values [3]

Ausbeuten von Aerosolvorlaeufersubstanzen bei der DMS-Oxidation als Funktion von atmosphaerischen Bedingungen (Temperatur und NO_x) Abschlussbericht

In-depth analyses have been made of the products and aerosol formation from the OH-radical initiated oxidation of dimethyl sulphide (CH3SCH3: DMS) as a function of temperature, O2 partial pressure and initial NO concentration in large photoreactors. The investigations have provided new insights into the oxidation mechanisms of both DMS and DMSO, e.g., it has been shown that interactions of the DMS-OH adduct with O2 form DMSO in the absence of NO and dimethyl sulphone (CH3SO2CH3: DMSO2) in its presence. The data support an SO2 yield of around 70% from OH + DMS in the remote marine atmosphere. Investigations on the OH-radical initiated oxidation of dimethyl sulphoxide (CH3SOCH3: DMSO) have shown for the first time that methane sulphinic acid (CH3S(O)OH: MSIA) is the major product. Within the experimental conditions employed in the experiments only a modest dependence of the aerosol yield on temperature and initial NO concentration was observed. The experiments support that sulphuric acid formed from OH + SO2 is the major component of the aerosol with only minor contributions from MSA and MSIA. The mechanistic information is being incorporated into a DMS atmospheric chemistry modeule for CTMs (http://www.dmi.dk/f+u/luft/eng/elcid/elcid.html target=NewWindow> http://www.dmi.dk/f+u/luft/eng/elcid/elcid.html ) and also in a simplified form for a global climate model (http://ask.ii.uib.no/.climate/elcid/ target=NewWindow> http://ask.ii.uib.no/.climate/elcid/ ). (orig.)SIGLEAvailable from TIB Hannover: F02B1558 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Gas-phase ozonolysis of trans-2-hexenal: Kinetics, products, mechanism and SOA formation

International audienceIn this work, kinetics, product formation, chemical mechanism and SOA formation for the gas-phase reaction of trans-2-hexenal (T2H) with O3 are examined using four complementary experimental setups at 298 ± 2 K and atmospheric pressure. Product studies were conducted in two contrasted experimental conditions, with and without OH radical scavenger. The ozonolysis rate constant was determined in both static and dynamic reactors. An average reaction rate constant of (1.52 ± 0.19) × 10−18 cm3 molecule−1 s−1 was determined. Glyoxal and butanal were identified as main products with molar yields of 59 ± 15% and 36 ± 9%, respectively, in the presence of an OH scavenger. Slightly lower values were obtained in the absence of scavenger. Acetaldehyde, propanal and 2-hydroxybutanal were also identified and quantified. A reaction mechanism was proposed based on the observed products. SOA formation was observed with aerosol mass yields andgt;13% for SOA masses of 400 μg m−3. This work demonstrates for the first time that 2-alkenals ozonolysis can be a source of SOA in the atmosphere

Experimental and Theoretical Studies of Trans-2-Pentenal Atmospheric Ozonolysis

International audienceWe investigated the kinetics, mechanism and secondary organic aerosols formation of the ozonolysis of trans-2-pentenal (T2P) using four different reactors with Fourier Transform InfraRed (FTIR) spectroscopy and Gas Chromatography (GC) techniques at T = 298 ± 2 K and 760 Torr in dry conditions. The rate coefficients and branching ratios were also evaluated using the canonical vari-ational transition (CVT) state theory coupled with small curvature tunneling (CVT/SCT) in the range 278–350 K. The experimental rate coefficient at 298 K was (1.46 ± 0.17) × 10−18 cm3 molecule−1 s−1, in good agreement with the theoretical rate. The two primary carbonyls formation yields, gly-oxal and propanal, were 57 ± 10% and 42 ± 12%, respectively, with OH scavenger compared to 38 ± 8% for glyoxal and 26 ± 5% for propanal without OH scavenger. Acetaldehyde and 2-hydroxypro-panal were also identified and quantified with yields of 9 ± 3% and 5 ± 2%, respectively, in the presence of OH scavenger. For the OH production, an upper limit of 24% was estimated using me-sitylene as OH tracer. Combining experimental and theoretical findings enabled the establishment of a chemical mechanism. Finally, the SOA formation was observed with mass yields of about 1.5%. This work provides additional information on the effect of the aldehyde functional group on the fragmentation of the primary ozonide. © 2022 by the authors. Licensee MDPI, Basel, Switzerland