Composition of atmospheric precipitation

Eriksson E., Composition of atmospheric precipitation. I. Nitrogen compounds. Tellus , 4, 215-232 (1952). 

Granat, L. 1972. On the relation between pH and the chemical composition of atmospheric precipitation. Tellus 24 550-60. 

The processes which influence the chemical composition of atmospheric precipitation can be investigated using the chemical reactions taking place in atmosphere. It is interesting to follow the possible ways of formation of different compounds in the atmosphere in die selected area in relation to the composition of the emissions of harmful substances into the... 

The effect of emissions on the chemical composition of atmospheric precipitation was investigated taking Almalyk town as an example. A lot of industrial objects are located in Almalyk town construction enterprises and chemical plants Almalyk mining and smelting plant. 

The chemical composition of atmospheric precipitation was analyzed by the methods of ion chromatography, atomic adsorption, photo-colorimetry and other techniques, in accordance with documented methodical guidelines (Brimblecombe, 1988 SANIGMI, 1993b Gidrometeoizdat, 1996 Isidorov, 2001). 

When studying the chemical composition of atmospheric precipitation it is possible to assess the pollution of the atmosphere, and consequently, to evaluate the ecological conditions of the region. For the evaluation of the present state of the atmosphere for the exemplary cases of Almalyk, Tashkent and Chirchik towns, the composition of emissions, using statistic reports, as well as seasonal dynamics of emissions has been investigated. The data from systematic observations of the atmospheric pollution in these towns (data of observations made at three stationary posts) were generalized. 

Table I. Composition of Atmospheric Precipitation in the Mattole River Basin...

Emanuelson, A., E. Erikson, and H. Egner (1954). Composition of atmospheric precipitation in Sweden. Tellus 6, 261-267. 

Eriksson, E. (1952b). Composition of atmospheric precipitation. II. Sulfur, chloride, iodine compounds bibliography. Tellus 4, 280-303. 

The net result of evaporative isotopic fractionation of lake water is a water mass that is not in isotopic equilibrium with its water sources. Therefore, the isotopic composition of a lake water should plot below the LM WL, as shown in Figure 2. The line that passes through the isotopic composition of a lake water and its volume-weighted input from precipitation and ground-water is referred to as an evaporation line. This line represents the isotopic evolution of lake water from its source waters. The slope of an evaporation line is a function of humidity, temperature, and the isotopic composition of atmospheric moisture above the lake the slope generally ranges from about 3.5 to 6.0 (23). 

Rainwater composition is determined by the atmospheric composition of the precipitation zone and by that of the zone of origin of the clouds and the winds that carry them to the precipitation site. It varies geographically and depends on the natural and anthropogenic input of gases and particles into the atmosphere, as well as on the atmospheric reactions that may transform them. Activity of the local biomes (see definition in Section 7.3) also affects rainwater composition as does the local weather, which in turn defines the amount of precipitation and therefore the concentration of components. 

The discovery of the anomalous oxygen isotopic compositions of atmospheric sulfate provides a new means for identifying sulfate of atmospheric origin. Rainwater and aerosols from southern California were found to have A O values in the range of 0%o to -K.5%o (Lee et al., 2001). The average A O of snow sulfate in the Rocky Mountains (Colorado, USA) was - -1.3%o. Sulfate in ice cores, massive sulfate deposits, and Dry Valley soils from various locations also have MIF (Bao et al., 2000 Lee et al., 2001). There appears to be seasonality in the A O of sulfate in precipitation, with higher values in the winter and lower values in the summer, probably due to seasonal changes in climatic elfects that favor aqueous phase S(IV) oxidation in winter relative to summer (Lee and Thiemens, 2001). 

Presently it is well established that the chemical composition of wet precipitation is strongly affected by the chemical composition of the atmosphere, and is especially affected by the source zone traversed by the cloud system. Particles and gases either incorporated directly... 

Observations of the chemical composition of atmospheric fallouts (dry precipitation) have been carried out in Tashkent since the 80s of the last century, in accordance wifli standardization procedures worked out at SANIGMI. Chemical analyses of the atmospheric air samples and atmospheric fallouts were made using the methods of atomic adsorption, ion chromatography, photo-colorimetry, etc. 

Assessment of the Role of Chemical Composition of Atmospheric Fallouts (dry precipitation) as an Indicator of Atmospheric Pollution... 

The seasonal variations of trace metal composition of atmospheric aerosols are controlled by several meteorological factors such as temperature, humidity and wind velocity and direction. Cold seasons are usually characterized by persistent thermal inversions, high precipitation and low wind velocities which favor the accumulation of anthropogenic exhaust emissions and reduce the presence of road... 

Because of the mixture of VOCs in the atmosphere, the composition of smog reaction products and intermediates is extremely complex. formed via reaction 16, is important because when dissolved in cloud droplets it is an important oxidant, responsible for oxidising SO2 to sulfuric acid [7664-93-9] H2SO4, the primary cause of acid precipitation. The oxidation of many VOCs produces acetyl radicals, CH CO, which can react with O2 to produce peroxyacetyl radicals, CH2(C0)02, which react with NO2... 

In an oversimplified way, it may be stated that acids of the volcanoes have reacted with the bases of the rocks the compositions of the ocean (which is at the fkst end pokit (pH = 8) of the titration of a strong acid with a carbonate) and the atmosphere (which with its 2 = 10 atm atm is nearly ki equdibrium with the ocean) reflect the proton balance of reaction 1. Oxidation and reduction are accompanied by proton release and proton consumption, respectively. In order to maintain charge balance, the production of electrons, e, must eventually be balanced by the production of. The redox potential of the steady-state system is given by the partial pressure of oxygen (0.2 atm). Furthermore, the dissolution of rocks and the precipitation of minerals are accompanied by consumption and release, respectively. 

The composition of the earth s atmosphere differs from day to day, from altitude to altitude, and from place to place. The largest variation is in the concentration of water vapor. Water evaporates continually from the hydrosphere, from the soil, from leaves, from clothes drying, etc. At intervals, parts of the atmosphere become chilled until the dew point or frost point is reached and then any vapor in excess of the saturation amount is precipitated as rain or snow. 

The deposition velocities depend on the size distribution of the particulate matter, on the frequency of occurrence and intensity of precipitation, the chemical composition of the particles, the wind speed, nature of the surface, etc. Typical values of and dj for particles below about 1 average residence time in the atmosphere for such particles is a few days. 

Fig. 18-6 Characteristic air-mass trajectory and corresponding per mil isotopic composition of precipitation, along a transect from the subtropics to a polar ice sheet. This is a highly schematic view of the true atmospheric system.

The global atmospheric circulation acts as an enormous filtration system, which depletes high-latitude precipitation of heavy isotope-bearing water molecules. Because of this system, measurements of the stable isotopic composition of the ice sheets and of ocean-floor sediments reveal very important paleo-environmental information (see Sections 18.2.2,18.3.2, and 18.3.3). Here we examine this filtration system at a physical level. This system was first understood by a great Danish geochemist named Willi Dansgaard (Dansgaard, 1964). 

Water vapor enriched in oxygen-16 is transported by wind in the atmosphere from the sea to land. When the water vapor condenses and precipitates as rain, snow, or hail, the water becomes rich in oxygen-16. Eventually the oxygen-16 rich water is incorporated into rivers, lakes, glaciers, and polar ice, which are, therefore, also rich in oxygen-16. Thus the isotopic composition of groundwater and the water of rivers, lakes, and glaciers is not the same as in seas and oceans. 

Three processes that take place in living organisms - respiration in animals and plants, photosynthesis only in plants, and the precipitation of solids by some aquatic animals - have altered the primeval composition of the outer solid, liquid, and gaseous layers of the earth. Respiration consumes oxygen from the atmosphere and creates carbon dioxide. Photosynthesis, which does the opposite (consumes carbon dioxide and releases oxygen), has... 

---