Atmosphere and Climate

Yeqiao Wang, Yeqiao Wang

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9780429804656
• Edition: 2
• Topic: Biological Sciences
• Subtopic: Environmental Conservation & Protection
• Index: Biological Sciences

Authored by world-class scientists and scholars, The Handbook of Natural Resources, Second Edition, is an excellent reference for understanding the consequences of changing natural resources to the degradation of ecological integrity and the sustainability of life. Based on the content of the bestselling and CHOICE-awarded Encyclopedia of Natural Resources, this new edition demonstrates the major challenges that the society is facing for the sustainability of all well-being on the planet Earth. The experience, evidence, methods, and models used in studying natural resources are presented in six stand-alone volumes, arranged along the main systems of land, water, and air. It reviews state-of-the-art knowledge, highlights advances made in different areas, and provides guidance for the appropriate use of remote sensing and geospatial data with field-based measurements in the study of natural resources.

Volume 6, Atmosphere and Climate, covers atmospheric pollution and the complexity of atmospheric systems and their interactions with human activity. As an excellent reference for fundamental information on air systems, the handbook includes coverage of acid rain and nitrogen deposition, air pollutants, elevated carbon dioxide, atmospheric circulation patterns, and climate change effects on polar regions and climatology. New in this edition are discussions on aerosols monitoring and mapping, greenhouse gases, the Greenland ice sheet, and mountainous regions. This book presents the key processes, methods, and models used in studying the impact of air pollution on ecosystems worldwide.

Written in an easy-to-reference manner, The Handbook of Natural Resources, Second Edition, as individual volumes or as a complete set, is an essential reading for anyone looking for a deeper understanding of the science and management of natural resources. Public and private libraries, educational and research institutions, scientists, scholars, and resource managers will benefit enormously from this set. Individual volumes and chapters can also be used in a wide variety of both graduate and undergraduate courses in environmental science and natural science at different levels and disciplines, such as biology, geography, earth system science, and ecology.

I

Atmosphere

1

Acid Rain and Nitrogen Deposition

George F. Vance

University of Wyoming

Introduction

Sources and Distribution

Human Health Effects

Structural Impacts

Ecosystem Impacts

Soils • Agricultural Ecosystems • Forest Ecosystems • Aquatic Ecosystems

Reducing Acidic Deposition Effects

References

Introduction

Air pollution has occurred naturally since the formation of the Earth’s atmosphere; however, the industrial era has resulted in human activities greatly contributing to global atmospheric pollution.^[1,2] One of the more highly publicized and controversial aspects of atmospheric pollution is that of acidic deposition. Acidic deposition includes rainfall, acidic fogs, mists, snowmelt, gases, and dry particulate matter.^[3] The primary origin of acidic deposition is the emission of sulfur dioxide (SO₂) and nitrogen oxides (NO_x) from fossil fuel combustion; electric power generating plants contribute approximately two-thirds of the SO₂ emissions and one-third of the NO_x emissions.^[4]

Acidic materials can be transported long distances, some as much as hundreds of kilometers. For example, 30–40% of the S deposition in the northeastern U.S. originates in industrial midwestern U.S. states.^[5] After years of debate, U.S. and Canada have agreed to develop strategies that reduce acidic compounds originating from their countries.^[5,6] In Europe, the small size of many countries means that emissions in one industrialized area can readily affect forests, lakes, and cities in another country. For example, approximately 17% of the acidic deposition falling on Norway originated in Britain and 20% in Sweden came from eastern Europe.^[5]

The U.S. EPA National Acid Precipitation Assessment Program (NAPAP) conducted intensive research during the 1980s and 1990s that resulted in the “Acidic Deposition: State of the Science and Technology” that was mandated by the Acid Precipitation Act of 1980.^[6] NAPAP Reports to Congress have been developed in accordance with the 1990 amendment to the 1970 Clean Air Act and present the expected benefits of the Acid Deposition Control Program^[6,7] http://www.nnic.noaa.gov/CENR/NAPAP/. Mandates include an annual 10 million ton or approximately 40% reduction in point-source SO₂ emissions below 1980 levels, with national emissions limit caps of 8.95 million tons from electric utility and 5.6 million tons from pointsource industrial emissions. A reduction in NO_x of about 2 million tons from 1980 levels has also been set as a goal; however, while NO_x has been on the decline since 1980, projections estimate a rise in NO_x emissions after the year 2000. In 1980, the U.S. levels of SO₂ and NO_x emissions were 25.7 and 23.0 million tons, respectively.

Acidic deposition can impact buildings, sculptures, and monuments that are constructed using weatherable materials like limestone, marble, bronze, and galvanized steel,^[7,8] http://www.nnic.noaa.gov/CENR/NAPAP/. While acid soil conditions are known to influence the growth of plants, agricultural impacts related to acidic deposition are of less concern due to the buffering capacity of these types of ecosystems.^[2,5] When acidic substances are deposited in natural ecosystems, a number of adverse environmental effects are believed to occur, including damage to vegetation, particularly forests, and changes in soil and surface water chemistry.^[9,10]

Sources and Distribution

Typical sources of acidic deposition include coal- and oil-burning electric power plants, automobiles, and large industrial operations (e.g., smelters). Once S and N gases enter the Earth’s atmosphere they react very rapidly with moisture in the air to form sulfuric (H₂SO₄) and nitric (HNO₃) acids.^[2,3] The pH of natural rainfall in equilibrium with atmospheric CO₂ is about 5.6; however, the pH of rainfall is less than 4.5 in many industrialized areas. The nature of acidic deposition is controlled largely by the geographic distribution of the sources of SO₂ and NO_x (Figure 1.1). In the midwestern and northeastern U.S., H₂SO₄ is the main source of acidity in precipitation because of the coal-burning electric utilities.^[2] In the western U.S., HNO₃ is of more concern because utilities and industry burn coal with low S contents and populated areas are high sources of NO_x.^[2]

FIGURE 1.1 Acidic deposition across the U.S. during 1999.

Emissions of SO₂ and NO_x increased in the 20th century due to the accelerated industrialization in developed countries and antiquated processing practices in some undeveloped countries. However, there is some uncertainty as to the actual means by which acidic deposition affects our environment,^[11,12] http://nadp.sws.uiuc.edu/isopleths/maps1999/. Chemical and biological evidence, however, indicates that atmospheric deposition of H₂SO₄ caused some New England lakes to decrease in alkalinity.^[13,14] Many scientists are reluctant to over-generalize cause and effect relationships in an extremely complex environmental problem. Although, the National Acid Deposition Assessment Program has concluded there were definite consequences due to acidic deposition that warrant remediation^[6,7] http://www.nnic.noaa.gov/CENR/NAPAP/. Since 1995, when the 1990 Clean Air Act Amendment’s Title IV reduction in acidic deposition was implemented, SO₂ and NO_x emissions have, respectively, decreased and remained constant during the late 1990s.^[4]

Both H₂SO₄ and HNO₃ are important components of acidic deposition, with volatile organic compounds and inorganic carbon also components of acidic deposition-related emissions. Pure water has a pH of 7.0, natural rainfall about 5.6, and severely acidic deposition less than 4.0. Uncontaminated rainwater should be pH 5.6 due to CO₂ chemistry and the formation of carbonic acid. The pH of most soils ranges from 3.0 to 8.0.^[2] When acids are added to soils or waters, the decrease in pH that occurs depends greatly on the system’s buffering capacity, the ability of a system to maintain its present pH by neutralizing added acidity. Clays, organic matter, oxides of Al and Fe, and Ca and Mg carbonates (limestones) are the components responsible for pH buffering in most soils. Acidic deposition, therefore, will have a greater impact on sandy, low organic matter soils than those higher in clay, organic matter, and carbonates. In fresh waters, the primary buffering mechanism is the reaction of dissolved bicarbonate ions with H⁺ according to the following equation:

${\text{H}}^{+}+{\text{HCO}}_3^{-}={\text{H}}_2\text{O}+{\text{CO}}_2(1.1)$

Human Health Effects

Few direct human health problems have been attributed to acidic deposition. Long-term exposure to acidic deposition precursor pollutants such as ozone (O₃) and NO_x, which are respiratory irritants, can cause pulmonary edema.^[5,6] Sulfur dioxide (SO₂) is also a known respiratory irritant, but is generally absorbed high in the respiratory tract. Indirect human health effects due to acidic deposition are more important. Concerns center around contaminated drinking water supplies and consumption of fish that contain potential toxic metal levels. With increasing acidity (e.g., lower pH levels), metals such as mercury, aluminum, cadmium, lead, zinc, and copper become more bioavailable.^[2] The greatest human health impact is due to the consumption of fish that bioaccumulate mercury; freshwater pike and trout have been shown to contain the highest average concentrations of mercury.^[5,15] Therefore, the most susceptible individuals are those who live in an industrial area, have respiratory problems, drink water from a cistern, and consume a significant amount of freshwater fish.

A long-term urban concern is the possible impact of acidic deposition on surface-derived drinking water. Many municipalities make extensive use of lead and copper piping, which raises the question concerning human health effects related to the slow dissolution of some metals (lead, copper, zinc) from older plumbing materials when exposed to more acidic waters. Although metal toxicities due to acidic deposi...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Table of Contents
• Preface
• About The Handbook of Natural Resources
• Acknowledgments
• Aims and Scope
• Editor
• Contributors
• Section I Atmosphere
• Section II Weather and Climate
• Section III Climate Change
• Index