Soil and the Atmosphere

The uptake and biotransformation of benzene from soil and the atmosphere has been studied in a nnmber of plants. It was shown that in leaves of spinach Spinacia oleraced) the label in -benzene was fonnd in mnconic, fnmaric, snccinic, malic, and oxalic acids, as well as in specific amino acids, and that an enzyme preparation in the presence of NADH or NADPH prodnced phenol (Ugrekhelidze et al. 1997). 

Paterson S, Mackay D (1994) A model of organic chemical uptake by plants from soil and the atmosphere. Environ Sci Technol 28 2259-2266... 

As a rule the amount of nitrate nitrogen is approximately half that of the ammoniacal. The ammonia appears to arise from several sources. The sea, the soil, and the atmospheric pollution consequent upon inhabited areas may all contribute. That the soil is an important... 

Haygarth, P.M., Harrison, A.F., and Jones, K.C. 1995. Plant selenium from soil and the atmosphere. Journal of Environmental Quality, 24 768-71. 

Hamer, T. Mackay, D. Jones, K.C., Model of the long-term exchange of PCBs between soil and the atmosphere in the southern U.K. Environ. Sci. Technoi. 1995, 29, 1200-1209. 

Respired CO2 exit the soil largely via molecular diffusion, resulting in the more rapid escape of the lighter CO2 molecule with an expected kinetic fractionation, Sq, of 8.8 %c between soil CO2 at the soil-air interface and the flux of CO2 into the atmosphere. This theoretical value of 8.8%o is based on simple kinetic theory and the reduced mass of CO2 and air (Craig, 1953) but has not been measured, and it does not consider any effect of pressure gradients between the soil and the atmosphere. Sq can only be fully expressed if CO2 and water are in complete isotopic equilibrium until the soil surface. Since CO2 diffuses out of the soil faster than it can equilibrate with soil water, CO2 remaining in the soil will be enriched in 0, relative to its equilibrium value with water, as also predicted for in soils (Cerhng,... 

Weathering occurs because rocks and minerals become exposed to physical and chemical conditions different from those under which they formed. Weathering in the pedosphere takes place close to the surface where the overburden pressure and temperature are low, and H2O is plentiful. Because most soils harbor large numbers of microorganisms, their metabolic activity results in the consumption of O2 and production of CO2. The partial pressure of CO2 in soil may be 10-100 times greater than that of the atmosphere (Holland, 1978). Under waterlogged conditions, where gas diffusion between the soil and the atmosphere is impeded, the oxygen partial pressure may approach zero and the soil solution may contain CO2, CH4, and H2S. Under these conditions, Fe and Mn may become soluble. 

Partition between vegetation and the atmosphere and between the soil and the atmosphere should also be considered its significance in the accumula-... 

Ryden, J. C. (1981). N20 exchange between a grass land soil and the atmosphere. Nature 292, 235-237. 

Conen, F. and Smith, K. A., An explanation of linear increases in gas concentration under closed chambers used to measure gas exchange between soil and the atmosphere, Eur. J. Soil Set, 51,... 

Ammonia loss through volatilization to the atmosphere is a complex process mediated by a combination of physical, chemical, and biological factors. The exchange of ammonia between water column, soils, and the atmosphere plays an important role in wetland nitrogen cycle. However, the significance of this process is not well established. 

Reduction of oxygen is the dominating cathodic reaction in natural environments like seawater, fresh water, soil and the atmosphere. However, under eertain conditions there are also other important cathodic reactions the hydrogen reaetion 2H +2e H2, reduction of carbonic acid (H2CO3) (in oil and gas production), reduction of metal ions etc. Various cathodic reactions arc dealt with in Chapter 6. 

Studies of pollutants include the investigation of pollutant movements in water, soil, and the atmosphere. The tracer may be of natural or artificial origin. A widely studied large-scale case is the Chernobyl accident of 1986. 

Environmental samples offer a challenge to the analytical chemist because of the matrices involved. These include, among others, fresh- and seawater, sediments, marine and biological specimens, soil, and the atmosphere. For determining trace concentrations of vanadium in these complex matrices, preconcentration and separation techniques may be required prior to instrumental analysis. Hirayama et al. [14] summarize the various preconcentration and separation techniques including chelation, extraction, precipitation, coprecipitation, ion exchange in conjunction with the instrumental method of spectrometry, densitometry, flow injection, NAA, AAS, X-ray fluorescence, and inductively coupled plasma atomic emission spectrometry (ICPAES). While NAA offers great sensitivity and selectivity, its application is limited by the number of research reactors available worldwide. 

Chromium, in the environment, commonly exists as Cr(IIl) and Cr(VI). The Cr(III) species is a trace element and supports the chemistry of living organisms. Conversely, Cr(VI) is a most unpleasant species inducing serious medical conditions such as asthma and dermatitis. Cr(VI) species are highly soluble and this ensures a wide dispersion in water, in soils and the atmosphere, whereas Cr(in) species are sparingly soluble. 

Capping is done to cover the wastes, prevent infiltration of excessive amounts of surface water, and prevent release of wastes to overlying soil and the atmosphere. 

Paterson, S., D. Mackay, and C. McFarlane. 1994. A model of organic chemical uptake by plants from soil and the atmosphere. Environ. Set Technol. 28 (13) 2259-2266. Pauliukonis, N. and R. Schneider. 2001. Temporal patterns in evapotranspiration from lysime-ters with three common wetland plant species in the eastern United States. Aquatic Bot. 71(1) 35-46. 

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