Acid deposition controlling effects

Cosby, B.J et al., Modeling the effects of acid deposition Control of long-term sulfate dynamics by soil sulfate adsorption, Water Resour. Res., 22, 1283, 1986. 

Innes, J.L. (1989). Acid rain and trees. In, Acid deposition. Sources, effects and controls, ed. J.W.S. Longhurst, 229-242. British Library, London. 

On this topic, J.W.S. Longhurst also edited the volume Acid Deposition Sources, Effects and Controls , published jointly by the British Library and Technical Communications in 1989. 

The harmful effects of air pollutants on human beings have been the major reason for efforts to understand and control their sources. During the past two decades, research on acidic deposition on water-based ecosystems has helped to reemphasize the importance of air pollutants in other receptors, such as soil-based ecosystems (1). When discussing the impact of air pollutants on ecosystems, the matter of scale becomes important. We will discuss three examples of elements which interact with air, water, and soil media on different geographic scales. These are the carbon cycle on a global scale, the sulfur cycle on a regional scale, and the fluoride cycle on a local scale. 

Controlling the effects of acid deposition by the use oflime or other acid-neutralizing compounds has been tried, but mainly on an experimental basis. Adding lime to lakes usually has only a short-term effect in terms of neutralizing lake acidity. The longevity of the effect is directly related to lake s... 

After equilibrium, filtration, and pH adjustment, the residual calcium ion concentration was then titrated by EDTA solution. A higher residual calcium ion concentration indicates better inhibition activity and, therefore, more effectiveness in controlling calcium carbonate deposition in the treated water. As shown in Table III, at dosages of 1 to 5 ppm, the polyacrylic acid was more effective than the acrylic acid/N-(hydroxyalkyl)-acrylamide copolymers. 

Given that the source of oxidants for S02 in both the gas and liquid phases is the VOC-NO chemistiy discussed earlier and that a major contributor to acid deposition is nitric acid, it is clear that one cannot treat acid deposition and photochemical oxidant formation as separate phenomena. Rather, they are very closely intertwined and should be considered as a whole in developing cost-effective control strategies for both. For a representative description of this interaction, see the modeling study of Gao et al. (1996). 

One of the key issues in developing effective control strategies for acid deposition has been what is known as linearity. This term has been subject to a variety of interpretations and meanings and applied on microscopic, i.e., molecular, to macroscopic scales. A detailed treatment and discussion of linearity encompassing these scales is given by Hales and Renne (1992). 

The CASTNET provides atmospheric data on the dry deposition component of total acid deposition, ground-level ozone, and other forms of atmospheric pollution. CASTNET is considered the nation s primary source for atmospheric data to estimate dry acidic deposition and to provide data on rural ozone levels. Used in conjunction with other national monitoring networks, CASTNET is used to determine the effectiveness of national emission control programs. Established in 1987, CASTNET now comprises over 70 monitoring stations across the United States. The longest data records are primarily at eastern sites. The majority of the monitoring stations are operated by EPA s Office of Air and Radiation however, approximately 20 stations arc operated by the National Park Service in cooperation with EPA. 

Recent concern for the role of sulfate in acidic deposition has intensified the need for a more accurate estimation of natural sulfur emissions in the United States. The magnitude and the spatial and temporal distribution of natural sulfur emissions must be quantified in order to be useful in efforts to predict the effectiveness of various control strategies for acid deposition. The inventoiy estimates described in this paper predict monthly sulfur emissions from each county in the contiguous United States. Improvements in the methodology used to calculate this natural emissions inventory may be a useful guide in the calculation of the national emissions inventories of other naturally emitted compounds which have the potential to make significant contributions to regional air quality. 

Only a few papers in this symposium directly address the issue of acid deposition. Almost all, however, are related to some aspect of the problem. The chemistry and effects of combustion-derived air pollutants, as well as methods for characterizing these emissions, are reported. In addition, a number of papers focus on the three categories of control options available for reducing SO2 and N0X precombustion, during combustion, and postcombustion. 

The optinum acid treatment conditions should he properly controlled to make only some few of framework A1 atoms to be removed while the zeolite framework could not be collapsed. The increased Si/Al ratio by acid dealumination may effectively suppress the carbon deposition on the surface of catalyst during the hydrocarbon cracking reactions. 

Psenner R. and Schmidt R. (1992) Climate driven pH control of remote alpine lakes and effects of acid deposition. Nature 356, 781-783. 

The influence of a surface on an adsorbed species is well-accepted. The TA/Ni(l 10) system demonstrates how much the molecule can influence the behaviour of the surface. How far can an adsorbate like tartaric acid induce such effects Work by Switzer and co-workers on the electrodeposition of CuO films in the presence of tartaric acid showed that chirality could be induced in a normally achiral inorganic material [25]. In a standard electrochemical cell, a Au(OOl) crystal is placed in a solution containing Cu(II) ions, tartrate ions and NaOH. At a certain potential, CuO will deposit, as a thin-film on the Au Surface. Characterization by diffraction revealed that the deposited CuO film has no mirror or inversion elements, i.e. it is chiral. The chirality of the film is controlled by the chirality of the tartrate ions in the solution (/ ,/ )-tartrate yielding a chiral CuO(-lll) fihn while presence of (S,S )-tartrate produces the mirror Cu(l-l-l) enantiomorph. Switzer et al, by catalyzing the oxidation of tartaric acid, demonstrate that not only the bulk, but also the surface of the CuO film is chiral the CuO electrode surface grown in the presence of (/ ,/ )-tartrate is more effective at oxidizing (/ ,/ )-TA, while the surface deposited in the presence of (S,S )-tartrate is more effective at oxidizing (S,S )-TA. 

Based on the mineralogy controlling weathering and soil development, sensitivity of ecosystem to acid deposition is assessed with a comprehensive consideration on the effect of temperature, soil texture, land use and precipitation. The results show that the most sensitive area to acid deposition in China is Podzolic soil zone in the Northeast, then followed by Latosol, Dark Brown Forest soil and Black soil zones. The less sensitive area is Ferralsol and Yellow-Brown Earth zone in the Southeast, and the least sensitive areas are mainly referred to as Xerosol zone in the Northwest,... 

On the basis of this evidence, it is recommended that an experimental test program, consisting of both laboratory and field tests, be developed and Implemented to quantitatively measure the effects of acid deposition on both the as thetic and structural properties of PCC structures. It is, however, recommended that a preliminary series of controlled, accelerated laboratory tests be carried out before a full-scale field evaluation program is instituted. The objectives of the accelerated laboratory test program should be to identify the magnitude of the problem and to attempt to differentiate between the effects of wet deposition, dry deposition, and normal weathering. The preliminary test program should concentrate on surface chemistry effects and penetration rates of SO4, NOx, Cl as deposited from wet and dry deposition. The... 

Based on the mineralogy controlling weathering and soil development, sensitivity of ecosystems to acid deposition is assessed with the comprehensive consideration on the effect of temperature, soil texture, land use and precipitation. The results show... 

---