Materials Degradation Caused by Acid Rain

Downloaded by 80.82.77.83 on December 28, 2017 | http://pubs.acs.org Publication Date: September 25, 1986 | doi: 10.1021/bk-1986-0318.pr001

Left side-right side comparison of the Statue of Liberty torch shows darkening of the left side facing Manhattan and the northeast. Darkening of the left side is due to erosion of the green patina by acid deposition and the severe weather from the northeast. (Photo by Robert Baboian.)

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Baboian; Materials Degradation Caused by Acid Rain ACS Symposium Series; American Chemical Society: Washington, DC, 1986.


Corrosion of bronze, commonly termed "bronze plague," in the Torrey monument in Mount Auburn Cemetery, Cambridge, MA, due to the effects of acid deposition. (Photo by Robert Baboian.)

Corrosion of reinforcing steel in concrete (elevated highway, Providence, RI), where road de-icing salts combine with acid precipitation to produce a severe environment. (Photo by Robert Baboian.)

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PREFACE A C I D R A I N IS A N I M P O R T A N T A N D G R O W I N G T O P I C . 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 measurement and monitoring concentrates on the scope of the acid deposition problem. This includes wet deposition chemistry, dry deposition, fog and cloud water, and the composition of dew. The section on metallic corrosion clearly indicates that the conventional method of classification of environments into marine, industrial, and rural no longer is adequate. More specific information is needed about the actual chemical components in the atmosphere as well as humidity and other factors. Specific environments also are addressed in the metallic corrosion section. For example, the automotive environment in the northeastern United States is particularly severe because of the combination of acid deposition and the use of road de-icing salts. These factors exert a synergistic effect on the corrosion behavior of auto-body steel and on exterior anodized aluminum automobile trim. The section on masonry deterioration focuses on limestone, coquina, sandstone, marble, concrete, brick, and mortar as related to acid deposition effects on structures such as buildings and on cultural resources such as monuments.

Auto body corrosion adjacent to stainless steel trim occurs in environments where de-icing salts are used. The effects of acid deposition combined with road salts produces a synergystic effect on the degradation of automobiles. (Photo by Robert Baboian.) XI



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. In summary, this book serves to provide information on the wide range of materials affected by acid deposition. Although a large amount of information is presented on this subject, it is evident that much remains to be done. A better understanding of the nature and mechanisms of materials damage by acid deposition could lead to a reduction or avoidance of this kind of damage. Thus, expenditures for work in this field could lead to huge annual dollar savings. ROBERT BABOIAN

Electrochemical and Corrosion Laboratory Texas Instruments Inc. Attleboro, MA 02703 Organizing Committee for the Symposium Robert Baboian, Chairman Texas Instruments Inc.

Richard A. Livingston Environmental Protection Agency

Edward Escalante, Session Chairman National Bureau of Standards

Hugh C. Miller National Park Service

David R. Flinn U.S. Bureau of Mines

Robert S. Shane, Session Chairman Shane Associates

James H. Gibson, Session Chairman Colorado State University

Susan Sherwood, Session Chairman National Park Service

Ray Hermann National Park Service

Thaddeus Whyte The PQ Corporation

Frederick W. Lipfert, Session Chairman Brookhaven National Laboratory

William E. Wilson Environmental Protection Agency

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Degradation of paint occurs by reaction at the surface and at the paint interface. Acid deposition can cause paint peeling on wood. (Photo by R. S. Williams.)

Bricks and mortar (New Haven, CT) are susceptible to deterioration through the action of acid deposition. (Photo by Robert Baboian.)

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St. Thomas Church in New York City. Areas on the facade accumulate a layer of gypsum (calcium sulfate) produced by acid deposition attack on the limestone and then darken by dirt, soot, and other combustion products. (Photo by Elena Charola.)

Spoiling of marble column on Department of Justice building, Washington, DC. (Photo by Bruce Doe.) xiv


Materials Degradation Caused by Acid Rain

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