Cloud water samples

Cloud Water and Precipitation Collectors. Several methods have been developed for collecting cloud water samples (24-26). Probably the device most commonly used in warm clouds is the slotted rod collector developed by the Atmospheric Science Research Center at the State University of New York (SUNY) at Albany. Commonly known as the ASRC collector (25), this collector consists of an array of rods constructed from Delrin (a form of nylon). Each rod is hollow and has a slot located at its forward stagnation line. The rod radius determines the collection efficiency as a function of particle size, the rods are sized to collect cloud droplets but not submicrometer aerosol particles, and the 50% cutoff is calculated to be at about 3 xm. 

Skarzynska, K., Z. Polkowska, and J. Namiesnik. 2006. Samples handling and determination of physicochemical parameters in rime, hoarfrost, dew, fog and cloud water samples—a review. Pol. J. Environ. Stud. 15 185-209. 

AUen JM, Eaust B (1994) Aqueous-phase photochemical formation of peroxyl radicals and singlet molecular oxygen in cloud water samples from across the United States. In Helz GR, Zepp RG, Crosby DG (eds) Aquatic and surface photochemistry. Lewis, Boca Raton, chap 18... 

The author (DM) had same experience with the Mt. Brocken Cloud Chemistry Climate Monitoring (BROCCMON) station with German Funding Agencies The station was only funded from 1992 until 1995 but remains in operation (now 18 years with more than 25000 one-hour analyzed cloud-water samples). We discovered in 1994 the cloud ozone hole (Acker et al. 1995). 

Experimental studies also show that nitrite in rainwater and cloud water samples exists for hours and even days, whereas S(IV) is oxidized in minutes. Therefore, it is very likely that especially at interfaces nitrite is accumulated and transferred back to the gas phase as HONO. Nitrite can be quickly oxidized back to NO2 by OH 5.215 = 4.5 10 L mol" s (Logager et al. 1993) thereby NO2 reduction (5.211) and oxidation (5.214) are in equilibrium ... 

Figures 19 and 20 illustrate the performance of the profile analysis instrument for atmospheric studies, by displaying the relaxation of dynamic surface tension (at constant surface area) for a cloud water sample and, respectively, the dynamic surface tension response to harmonic surface area disturbances for a marine water sample [74].

Fig. 19. Dynamic surface tension of a cloud-water sample, at constant air/water interfacial area, as observed a few seconds after formation of a bubble inside the liquid phase. Temperature T = 20 °C. ...

Analysis of aerosol samples obtained at several locations in Western Europe has shown that about 60% of the content of organic carbon in tropospheric aerosol is the share of water-soluble organic compounds. According to observational data, at a rural location in Austria, mono- and dicarboxylic acids constitute about 11 % (with respect to the total content of organic carbon in cloud water). While insoluble organic compounds hamper the assimilation of water by aerosol, soluble organic matter, as a rule, favors water assimilation. 

Cloud point phenomenon (cloud point extraction—CPE) Extracting analytes (both organic and inorganic) from water samples 58-65... 

Padron Sanz, C., Z. Sosa Ferrera, and J.J. Santana Rodriguez. 2002. Extraction and preconcentration of polychlorinated dibenzo-p-dioxins using the cloud-point methodology. Application to their determination in water samples by high-performance liquid chromatography. Anal. Chim. Acta 470 205-214. 

Yuan, Ch. G., G.B. Jiang, B. He, and J.F. Liu. 2005. Preconcentration and determination of tin in water samples by using cloud point extraction and graphite furnace atomic absorption spectrometry. Microchim. Acta 150 329-334. 

Farajzadeh, M.A. and M.R. Fallahi. 2006. Simultaneous cloud-point extraction of nine cations from water samples and their determination by flame atomic absorption spectrometry. Anal. Sci. 22 635-640. 

In some cases, ultrasonic nebulization or preconcentration is used to enhance detection limits. As, Se, and Sb were measured in cloud water detection limits were 20, 100, and 20 pg/mL, respectively, using pneumatic nebulization and four to five times lower using ultrasonic nebulization [311]. In another study [312], activated charcoal from a 1-L sample volume was used to preconcentrate Pd and Pt in fresh waters. Detection limits were 0.3-0.8 ng/L. An automated online preconcentration system based on a cationic resin (AG50W-X8) was used to measure Cd, Pb, Ni, Cu, and Zn. A preconcentration factor of 30 was obtained even with a sample throughput of 20 samples per hour [313]. 

A cloud water collector that separates unactivated (interstitial) particles from cloud droplets by jet impaction of these droplets on inert surfaces (12) provides a sample for chemical analyses. 

Background non-methane hydrocarbon levels are generally less than 20 ppbC. A typical sample (Table I) indicates that the major components are ethane, propane and acetylene. Because only picomolar amounts of these hydrocarbons would exist in the cloud water, the effects of these background levels on aqueous-phase chemistry are expected to be negligible. The effect of the organic acids is not expected to be significant unless sources of OH exist. Formaldehyde is known to inhibit aqueous SO2 oxidation, but its concentration here is insignificant compared to the concentrations of SO2 intentionally... 

Field studies of wet deposition processes require the differentiation and determination of many trace reactive species in the several phases (gaseous, aerosol, cloud water and precipitation) present in the atmosphere. The requirements imposed on existing analytical techniques by these studies have been extremely rigorous and, in several cases, have necessitated the development of new approaches to the sampling and determination of critical chemical species. 

Wen, Y., Li, J., Liu, J., Wenhui, L., Ma, J., Chen, L. Dual cloud point extraction coupled with hydrodynamicelectrokinetic two-step injection followed hy micellar electrokinetic chromatography for simultaneous determination of trace phenolic estrogens in water samples. Anal. Bioanal. Chem. 405, 5843-5852 (2013)... 

This paper is a summary of our findings from a four-year study of the chemical composition of fog and cloud water in California. Fog water was sampled at a number of sites with a rotating arm collector, which was developed in our laboratory and collects representative samples. Field investigations in the Los Angeles basin, the San Gabriel Mountains, and the San Joaquin Valley revealed very high ionic... 

In June of 1983, five different types of fog/cloud water collectors were compared under field conditions at Henninger Flats. Collectors designed by AeroVironment(AV), Caltech(CIT), the Desert Research Institute(DRI), Global Geochemistry(GGC), and the State University of New York(SUNY)-Albany were tested against one another. The mass and pH of the samples collected were measured on site while the detailed chemical analyses were performed by an independent laboratory, Rockwell International. Results of the intercomparison study, sponsored the the Coordinating Research Council, showed that the Caltech and DRI collectors performed the best over the broadest range of conditions At low liquid water content (i.e. LWC <... 

It is well known that, after its absorption, NOz forms nitric acid and nitrous acid in water. There is some indication that nitrite produced in this way is oxidized by dissolved 03 (Penkett, 1972). If neutralizing agents (ammonia, calcium carbonate etc.) are present, some nitrate salt is finally formed. It follows from this discussion that both S02 and N02 are oxidized in cloud water by atmospheric ozone. If this speculation is true a correlation should be found between the concentration of sulfate and nitrate ions in precipitation waters. Such a correlation was found in precipitation samples by Gambell and Fisher (1964) among others. However, correlations between any two species in rainwater must be considered with caution because the level of all ions is affected in a similar way by the precipitation intensity or quantity (see Subsection 5.4.1). Nevertheless the identical annual variations of the two ions in precipitation water (see Subsection 5.4.5) suggests that the two species are formed by some similar processes. 

For the investigation of the importance of the different wet removal processes, it is usual to compare the chemical composition of cloud and precipitation waters sampled simultaneously. This would appear to separate the effects of rain-out and wash-out. However, as we shall see, the results of such a comparison have to be considered with some caution. 

More recently, Fricke et al. (1978) reported the results of a similar investigation. In this study, carried out over Bavaria, F.R.G., the composition of cloud water collected at the cloud base was compared with the composition of rainwater sampled at the surface. It was found that the concentration of heavy metals at cloud base was about twice the value at ground level in rainwater, in agreement with some of the results of Petrenchuk and Drozdova (1966). Fricke s study also indicated that the total sulfur content (sulfate + S02 + sulfite about 30 % of the total was S02 and sulfite) was doubled between the cloud base and the surface, probably due to S02 wash-out. 

Fricke, W., Georgii, H. W. and Gravenhorst, G., 1978 Application of a new sampling device for cloud-water analysis. In Some problems of cloud physics. Gidrometeoizdat, Leningrad, 200-216. 

Fig. 8-11. Frequency distribution of pH values observed in hydrometeors. (A) Ernst (1938), 47 bulk rain samples collected in Bad Reinerz, combined with 80 samples showing a similar distribution collected in Oberschreiberhau (both locations in upper Silesia, central Europe), 1937-1938. (B) Mrose (1966), 206 bulk rain samples collected at Dresden-Wahnsdorf (German Democratic Republic), 1957-1964. (C) Esmen and Fergus (1976), about 200 individual rain drops collected during a single rainstorm in Delaware, 1974. (D, E) Likens etal. (1984), weekly samples of bulk rainwater collected at Hubbard Brook Experimental Forest Station, New Hampshire, D 1964-1968, E 1975-1979. (F) Falconer and Falconer (1980), 824 measurements of cloud water collected continuously at Whiteface Mountain, New York, 1977.

Ferrer, R., Beltran, J. L., and Guiteras, J., Use of cloud point extraction methodology for the determination of PAHs priority pollutants in water samples by high-performance liquid chromatography with fluorescence detection and wavelength programming. Anal. Chim. Acta, 330, 199-206, 1996. 

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