Multiphase chemistry of orographic clouds: observations at subalpine mountain sites

Lammel, Gerhard; Metzig, G.

doi:10.1007/bf00322431

Cited by 18 publications

(2 citation statements)

References 56 publications

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“…Dissolved organic carbon (DOC) was determined from filtered cloud water samples using a TOC-V CPH analyser (Shimadzu, Japan) in the NPOC (non-purgeable organic carbon) mode (van Pinxteren et al, 2009). Hydrogen peroxide (H 2 O 2 ) in solution was determined (in sum with organic peroxides) by fluorescence spectroscopy (Shimadzu RF-1501) following the method of Lazrus et al (1985). To stabilise peroxides during sample storage, p-hydroxyphenylacetic acid solution (POPHA) was added to aliquots of cloud water immediately after sampling to form a stable dimer (Rao and Collett, 1995).…”

Section: Chemical Analysesmentioning

confidence: 99%

Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

et al. 2016

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Abstract. Cloud water samples were taken in September/October 2010 at Mt. Schmücke in a rural, forested area in Germany during the Lagrange-type Hill Cap Cloud Thuringia 2010 (HCCT-2010) cloud experiment. Besides bulk collectors, a three-stage and a five-stage collector were applied and samples were analysed for inorganic ions (SO42−,NO3−, NH4+, Cl−, Na+, Mg2+, Ca2+, K+), H2O2 (aq), S(IV), and dissolved organic carbon (DOC). Campaign volume-weighted mean concentrations were 191, 142, and 39 µmol L−1 for ammonium, nitrate, and sulfate respectively, between 4 and 27 µmol L−1 for minor ions, 5.4 µmol L−1 for H2O2 (aq), 1.9 µmol L−1 for S(IV), and 3.9 mgC L−1 for DOC. The concentrations compare well to more recent European cloud water data from similar sites. On a mass basis, organic material (as DOC × 1.8) contributed 20–40 % (event means) to total solute concentrations and was found to have non-negligible impact on cloud water acidity. Relative standard deviations of major ions were 60–66 % for solute concentrations and 52–80 % for cloud water loadings (CWLs). The similar variability of solute concentrations and CWLs together with the results of back-trajectory analysis and principal component analysis, suggests that concentrations in incoming air masses (i.e. air mass history), rather than cloud liquid water content (LWC), were the main factor controlling bulk solute concentrations for the cloud studied. Droplet effective radius was found to be a somewhat better predictor for cloud water total ionic content (TIC) than LWC, even though no single explanatory variable can fully describe TIC (or solute concentration) variations in a simple functional relation due to the complex processes involved. Bulk concentrations typically agreed within a factor of 2 with co-located measurements of residual particle concentrations sampled by a counterflow virtual impactor (CVI) and analysed by an aerosol mass spectrometer (AMS), with the deviations being mainly caused by systematic differences and limitations of the approaches (such as outgassing of dissolved gases during residual particle sampling). Scavenging efficiencies (SEs) of aerosol constituents were 0.56–0.94, 0.79–0.99, 0.71–98, and 0.67–0.92 for SO42−, NO3−, NH4+, and DOC respectively when calculated as event means with in-cloud data only. SEs estimated using data from an upwind site were substantially different in many cases, revealing the impact of gas-phase uptake (for volatile constituents) and mass losses across Mt. Schmücke likely due to physical processes such as droplet scavenging by trees and/or entrainment. Drop size-resolved cloud water concentrations of major ions SO42−, NO3−, and NH4+ revealed two main profiles: decreasing concentrations with increasing droplet size and “U” shapes. In contrast, profiles of typical coarse particle mode minor ions were often increasing with increasing drop size, highlighting the importance of a species' particle concentration size distribution for the development of size-resolved solute concentration patterns. Concentration differences between droplet size classes were typically < 2 for major ions from the three-stage collector and somewhat more pronounced from the five-stage collector, while they were much larger for minor ions. Due to a better separation of droplet populations, the five-stage collector was capable of resolving some features of solute size dependencies not seen in the three-stage data, especially sharp concentration increases (up to a factor of 5–10) in the smallest droplets for many solutes.

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Section: Chemical Analysesmentioning

confidence: 99%

Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

et al. 2016

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“…Trace gases were measured using standard equipment (0,. SO,, NO,) in a distance of I km (SO,) and 3 km (0,, NO,), both outside the fogs, and a denuder method (NH,;Lammel, 1991) at the site. Fogwater pH was measured at the field site with an electrode.…”

Section: Measurementsmentioning

confidence: 99%

On the occurrence of nitrite in urban fogwater

Lammel

Metzig

1998

Chemosphere

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Nitrite was observed in fogwater samples 3 -52 pmol L', in a polluted source region in Germany. The fogwater contained high concentrations of various pollutants but only little or no acidity. The concentrations of oxidizable S(IV) were in the range 6 -290 pmol L-'.A two-phase chemical box model is used to interprete the chemistry. Fogwater N(II1) is found to be sensitive to gas-phase HNO, and also to HCHO (which were both not measured). From the distribution of S(IV) between oxidizable and non-oxidizable species (the latter is suspected to be dominated by the complex formed from S(IV) and dissolved HCHO), it is infered that HCHO most likely was low. The reaction between dissolved NO, and S(IV) was an important N(II1) source and could even explain the observed fogwater nitrite concentrations, if no gas-phase HNO, was fed into the fog. The comparison between observed and model predicted suggests that interphase mass transfer of NO, is characterized by a low mass accommodation coefficient.

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Atmosphärische Deposition von Spurenelementen in „Reinluftgebieten“

Matschullat¹,

Kritzer²

1997

Geochemie Und Umwelt

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Multiphase chemistry of orographic clouds: observations at subalpine mountain sites

Cited by 18 publications

References 56 publications

Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

On the occurrence of nitrite in urban fogwater

Atmosphärische Deposition von Spurenelementen in „Reinluftgebieten“

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