Abstract. The chemistry of N20 5 on liquid NaC1 aerosols or bulk NaC1 solutions was studied at 291 K by aerosol smog chamber and wetted-wall flow tube experiments. The uptake of N20 5 on deliquescent aerosol was obtained to be (3.2 + 0.2) x 10 -2 (lrr error) from the aerosol experiments. In the wetted-wall flow tube we observed that nitryl chloride (C1NO2) is the main product of the reaction at NaC1 concentrations larger than approximately 0.5 M and almost the only product at concentrations larger than I M. The C1NO: yield does not depend linearly on the NaC1 concentration, especially at small sodium chloride concentrations (i.e., smaller than 1 M). It appeared that a simple C1-) is unable to explain the observed concentration dependence of the product yield. We propose that N20 s dissociates to NO•-and NO•-(rate constant k I > 10 • s -•) mainly. The directly hydrolysis of N20 s (k3[H20]) is less than 20% of the total reaction. NO•-reacts with water to form 2H + and NO• (ks) or with C1-to form C1NO 2 (k4).Neglecting the influence of ionic strength we evaluate k4/k s to be 836 __ 32 (lo-error). Using the wetted-wall flow tube technique, we studied the uptake of nitryl chloride by aqueous solutions containing NaC1. We observed that the uptake coetScient 3• decreased from (4.84 +_ 0.13) x 10 -6 on pure water to (0.27 _+ 0.02) x 10 -6 on a 4.6 M NaC1

The reaction of alumina as a model substance for mineral aerosols with NO2 or HNO3 was studied using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The formation of nitrate on the Al2O3 surface was observed in both cases. In addition, during the initial phase of the NO2 reaction, intermediate nitrite formation was observed. The DRIFTS data provide insight into the reaction mechanism, which involves reaction of surface OH groups, the formation of a {AlOOH···NO2} adduct, and the formation of acidic OH groups. The reaction order in NO2 of 1.86 ± 0.1 was determined from a quantitative kinetic evaluation of a series of experiments with NO2 concentrations in the range of 1013 to 1015 molecules cm-3. The reactive uptake coefficient, γ, was determined from the infrared absorbance, which was calibrated by ion chromatography, and from the Al2O3 Brunauer−Emmett-Teller (BET) surface area. γ depended linearly on the NO2 concentration and varied from γ = 7.3 × 10-10 to 1.3 × 10-8 for [NO2] = 2.5 × 1013 to 8.5 × 1014 molecules cm-3. Estimations of the atmospheric impact showed that at these above conditions (γ = 10-9) nitrate formation on mineral aerosol from the NO2 reaction would be negligible.

The heterogeneous reactions leading to formation and loss of BrNO2 on salt solutions as a model substrate for atmospheric sea salt aerosol are investigated. Further to the reaction of ClNO2 with bromide solutions, the reaction of Br2 with nitrite solution was found to be a convenient method for the synthesis of BrNO2. We measured the temperature-dependent lifetime of BrNO2 in a quartz cell and obtained the activation energy E A = 89 ± 9 kJ/mol for the unimolecular decay at atmospheric pressure. The reactive uptake of BrNO2 and ClNO2 on water and aqueous solutions was determined using a wetted-wall flow tube technique. We observed the reactions Br2 + NO2 - ↔ BrNO2 + Br-, Cl2 + NO2 - → ClNO2 + Cl-, and the net reaction ClNO2 + Br- ↔ BrNO2 + Cl-. BrNO2 and ClNO2 both react with NO2 - to release NO2 into the gas phase. Observed concentration profiles in the gas phase and in solution can be described qualitatively by a numerical model of the diffusion and reaction processes in the experimental setup.

BackgroundDebilitating gastrointestinal symptoms (GIS) and dermatological injuries (DI) are common during and after endurance events and have been linked to performance decrements, event withdrawal, and issues requiring medical attention. The study aimed to determine whether GIS and DI affect food and fluid intake, and nutritional and hydration status, of ultramarathon runners during multi-stage (MSUM) and 24-h continuous (24 h) ultramarathons.MethodsAd libitum food and fluid intakes of ultramarathon runners (MSUM n = 54; 24 h n = 22) were recorded throughout both events and analysed by dietary analysis software. Body mass and urinary ketones were determined, and blood samples were taken, before and immediately after running. A medical log was used to monitor symptoms and injuries throughout both events.ResultsGIS were reported by 85 and 73 % of ultramarathon runners throughout MSUM and 24 h, respectively. GIS during MSUM were associated with reduced total daily, during, and post-stage energy and macronutrient intakes (p < 0.05), whereas GIS during 24 h did not alter nutritional variables. Throughout the MSUM 89 % of ultramarathon runners reported DI. DI during MSUM were associated with reduced carbohydrate (p < 0.05) intake during running and protein intake post-stage (p < 0.05). DI during 24 h were low; thus, comparative analyses were not possible. Daily, during running, and post-stage energy, macronutrient and water intake variables were observed to be lower with severity of GIS and DI (p < 0.05) throughout the MSUM only.ConclusionsGIS during the MSUM, but not the 24 h, compromised nutritional intake. DI presence and severity also compromised nutrient intake during running and recovery in the MSUM.

Mass spectrometric measurements of size and composition of diesel exhaust particles have been performed under various conditions: chassis dynamometer tests, field measurements near a German motorway, and individual car chasing. Nucleation particles consisting of volatile sulfate and organic material could be detected both at the chassis dynamometer test facility and during individual car chasing. We found evidence that if nucleation occurs, sulfuric acid/water is the nucleating agent. Low-volatile organics species condense only on the preexisting sulfuric acid/water clusters. Nucleation was found to depend strongly on various parameters such as exhaust dilution conditions, fuel sulfur content, and engine load. The latter determines the fraction of the fuel sulfur that is converted to sulfuric acid. The organic compounds (volatile and low-volatile) condense only on preexisting particles, such as both sulfuric acid nucleation particles and larger accumulation mode soot particles. On the latter, sulfuric acid also condenses, if the conditions for nucleation are not given. The overall ratio of sulfate to organic (volatile and low-volatile) is also strongly dependent on the engine load. It was found that the production of nucleation particles even at high engine load can be suppressed by using low-sulfur fuel.