Acid deposition materials, effects

Receptors. The receptor can be a person, animal, plant, material, or ecosystem. The criteria and hazardous air pollutants were so designated because, at sufficient concentrations, they can cause adverse health effects to human receptors. Some of the criteria pollutants also cause damage to plant receptors. An Air QuaUty Criteria Document (12) exists for each criteria pollutant and these documents summarize the most current Hterature concerning the effects of criteria pollutants on human health, animals, vegetation, and materials. The receptors which have generated much concern regarding acid deposition are certain aquatic and forest ecosystems, and there is also some concern that acid deposition adversely affects some materials. 

Both Watts and sulfamate baths are used for engineering appHcation. The principal difference in the deposits is in the much lower internal stress obtained, without additives, from the sulfamate solution. Tensile stress can be reduced through zero to a high compressive stress with the addition of proprietary sulfur-bearing organic chemicals which may also contain saccharin or the sodium salt of naphthalene-1,3,6-trisulfonic acid. These materials can be very effective in small amounts, and difficult to remove if overadded, eg, about 100 mg/L of saccharin reduced stress of a Watts bath from 240 MPa (34,800 psi) tensile to about 10 MPa (1450 psi) compressive. Internal stress value vary with many factors (22,71) and numbers should only be compared when derived under the same conditions. 

Acid deposition and the associated particulate nitrates and sulfates are implicated in the deterioration of certain sensitive ecosystems, decreased visibility, negative human health effects, and increased degradation of certain stone building materials and cultural resources, especially those made of limestone and marble. Fine particulate nitrate and sulfate particles... 

Some of the most dramatic environmental effects of acid deposition have involved buildings, statues, monuments, and other structures made of metal and stone. The explanation of this kind of damage is obvious Acids in acid deposition react with metals and with many of the compounds of which rock and other building material are made. For example, corrosion occurs when metals such as iron are exposed to hydrogen ions in the presence of oxygen ... 

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. 

Baedecker, P. A., et al. 1990. Acidic deposition, Rept. 19. In Effects of acidic deposition on material. Washington, DC State of Science Technol., Natl. Acid Precip. Assessment Program. 

Some years ago the first reports appeared on forest die-back in heavily polluted areas. The impact of this information drew the attention on the situation of local forests, which encouraged research on acid deposition in many countries. The quantitative evaluation of damage and the monitoring of forest quality are difficult. Most theories have been based on visual inspections however, trends, actual damage and local effects can only be estimated on the basis of scientific measurements, enabling to make correlations between damage and measured pollutant concentrations. A prerequisite for this evaluation is the availability of representative CRMs. The BCR has hence developed for this purpose two reference materials, namely beech leaves and spruce needles, which have been certified for nutrients (e.g. Ca, Mg, K, P and N) and indicator elements (e.g. S, Cl, A1 and Mn) [17-19],... 

NO in combination with SOp has a synergistic corrosion effect especially indoors on electrical contact materials, copper and steel. The influence of acid precipitation may differ for different metals and depends also on the pollution level. The atmospheric corrosion of metals due to acid deposition is in most regions mainly a local problem restricted to areas close to the pollution source. 

In 1981, a field study was initiated by the Bureau of Mines to determine the effects of the environment, including acid deposition, on the corrosion of a number of commonly used metallic materials of construction. This study, which is fully described in a recent paper (6), is being conducted at field sites where continuous air... 

Marble and limestone surfaces were exposed to atmospheric conditions at four eastern U.S. sites and were monitored for changes in surface chemistry, surface roughness/re-cession, and weight. The effect of acid deposition, to which calcareous materials are especially sensitive, was of particular interest. Results are described for the first year of testing, and aspects of a preliminary equation to relate damage to environmental factors are discussed. Thus far, findings support that acid deposition substantially damages marble and limestone surfaces. 

The deterioration of marble and limestone exposed both to anthropogenic acid deposition from the environment and to natural weathering is being assessed as one of the major activities of the Materials Effects Task Group of the National Acid Precipitation Assessment Program (NAPAP). There is much concern for the calcareous stone materials because of their widespread use as the exterior structure of commercial, institutional, and private buildings as well as in valued monuments and memorials. These calcium carbonate materials are especially sensitive to an acid environment. 

An objective of the program is to derive for each stone type a damage function in which the materials effects of the various components of acid deposition are quantified separately and apart from other damaging agents (such as natural rain at pH 5.6). The general form of a function might be as follows ... 

Acid Deposition Effects on Wood and Cellulosic Materials... 

Air pollution sources in the United States and Canada currently emit more than 25 million tons of sulfur dioxide each year. SO2 and wet acidic deposition are believed to cause damage to aquatic life, crops, forests, and materials. The effects on materials include damages to common construction materials including galvanized steel (zinc), paint, copper, building stones and mortar, as well as damages to cultural or historic objects and buildings. 

The new, hi er quality data do not resolve all the estimation difficulties, however. Because quantified damage functions are unavailable for sane materials at risk, comprehensive coverage is still not possible. In addition, estimating the aesthetic losses from the deterioration of cultural resources requires survey data, which are not available. Furthermore, major uncertainties in the physical damage functions are yet to be resolved, and these uncertainties are directly translated to the final economic estimates. Thus, at this point in time, the analysis cannot definitively establish the magnitude of all adverse effects the analysis can, however, provide a better indication than heretofore possible of whether or not the material damages from acid deposition are economically important. 

Flinn, D. R. Cramer, S. D. Carter, J. P. Spence, J. W. "Field Exposure Study for Determining the Effects of Acid Deposition on the Corrosion and Deterioration of Materials Description of Program and Preliminary Results." Durability of Building Materials pp. 147-175, 1985. 

LCID RAIN IS AN IMPORTANT AND GROWING TOPIC. This book addresses the important materials problems resulting from acid deposition. It is divided into five sections Measurement and Monitoring of Atmospheric Deposition, Metallic Corrosion, Masonry Deterioration, Degradation of Organics, and Economic Effects. 

The section on degradation of organics deals with paints, plastics, nylon, wood, and architectural organics. The effects of acid deposition on wood and other cellulosic materials are described. Strength losses in wood may be caused by hydrolytic degradation of the hemicelluloses and a sulfonation reaction of the lignin. Thus, the fibrils and matrix structure is affected. Cotton materials can be affected similarly, and soiling will result. The effect of acid deposition of nylon is indicative of a potentially shorter serviceable lifetime for outdoor fabrics. 

The section on economic effects presents the methodology used in assessing costs of degradation of materials due to acid deposition. The difficulty in accurately assessing the cost of materials degradation by acid deposition is described in this section. Thus, the various techniques used have a high degree of uncertainty. 

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