Geographic Areas of Acid Rain Concern
United States
The United States can be divided into two areas when looking at areas of high
acid rain concentration versus areas of low concentration. Generally speaking, the
Mississippi River serves as a good boundary line between the higher and lower acidity
levels in the country. West of the Mississippi River, hydrogen ion concentrations, or pH
levels, are at 5.0 and above, with only a few areas at about 4.8 or 4.9. East of the
Mississippi River, pH levels range from 4.7 down to below 4.3 (See Figure 1).
Therefore, the eastern United States is a critical area of concern in acid rain production
and deposition. This is especially true in the Northeast and in eastern parts of the
Midwest. This area has had a long history of coal burning and other industrial activity
which causes heavy environmental pollutants. The Ohio River Valley is the region with
the highest output of sulfur and nitrogen oxides in the country. Seven states in the valley,
Illinois, Indiana, Kentucky, Tennessee, Ohio, Pennsylvania, and West Virginia,
accounted for 41 percent of the national total emission in 1997 (Driscoll, 2001). As a
result of the winds carrying these pollutants eastward, the forests of the Northeast
coast/Appalachian region have suffered greatly from the gases that have fallen down on
them in the form of precipitation. The spruce trees in the highest elevations of the
Appalachians are at highest risk to exposition to liquid acidity since the trees actually
touch the acid clouds (Hart, 2001). Red spruce trees all across the northeast have
declined in growth, as well as sugar maple trees in central and western Pennsylvania
(Driscoll, 2001).
Canada
Eastern Canada is also facing major concerns with acid rain. There is a large
industrial output polluting the atmosphere mainly from oil refining and metal smelting in
the region. However, not all of the acid that is deposited on these forests is produced
locally. Many of the pollutants affecting Canadian forests come from industrial centers
in the Northeastern and Midwestern United States (Hart, 2001). The maple and
coniferous forests in the provinces of Ontario and Quebec are enduring damage from
heavy acid precipitation (See Figure 2). The Canadian Shield region of these two
provinces is particularly vulnerable to acid rain because of the igneous bedrock that exists
throughout. The carbonates in the bedrock do not have the capacity to buffer out acidity,
so the soils cannot keep the water at a constant pH, causing major damage to plant life in
the forests. In central Ontario, the average pH of rainfall is 4.2 (Stuart, year unknown).
Europe
North America is not the only part of the world experiencing acid rain problems.
Europe is greatly affected by this phenomenon as well. The main areas of concern are
particularly northern and central Europe (See Figure 3). Acid rain has plagued the forests
of the northeastern region of England with many areas reporting pH readings below 4.3
(See Figure 4). It is reported that much of the acid pollutants come from mainland
Europe. In Sweden, high amounts of sulfur and nitrogen linger overhead, thus is an area
of concern for acid rain. Only some of the pollutants deposited in Sweden are produced
within the country itself; most come from the British Isles and central and eastern
Europe. Finland has many of the same sources of acid rain as Sweden (Michaels, 2000).
In central Europe, acidity is very high with pH levels averaging 4.3 in parts of eastern
Germany, the Czech Republic, and Slovakia. Half of the trees in the Black Forest of
southwestern Germany are damaged by acid rain and other forms of pollutants (Hart,
2001). It is Poland however, that has the highest risk of acid rain in Europe. The
heaviest area of acid deposition lies in lower Selisia in southern Poland (See Figure 5).
The country’s industries are part of what put the forests of the upper Elbe/Older basin in
danger, but the main source of toxic pollutants comes from the southern region of what
used to be known as East Germany. For these reasons, the area encompassing eastern
Germany, the Czech Republic, and Poland has been named “The Black Triangle”
(Rautengarten, year unknown).
East Asia
East Asia is yet another area of concern in high acid rain concentration. This
region is very densely populated and its rate of population growth continues to skyrocket.
As a result, more industries have developed and therefore more output of sulfur and
nitrogen oxides has taken place. China is the country with the biggest output of
pollutants. There is a significant problem in the central and southeastern parts of China.
South of the Yangtze River and east of the Qinghai-Tibet plateau, acidity is at its highest
(See Figure 6). pH values lower than 4.5 were recorded in the southern cities of
Changsha, Zunyi, Hangzhou, and Yibin. Acid rain frequency was over 90% in the cities
of Changsha, Jingdezhen, and Zunyi. It is estimated that the sulfur dioxide emission,
which will significantly contribute to acid rain, will increase by about 7 million tons
every ten years (chinagate.com, 2002). Japan is another country that is currently facing a
problem with acid rain. About 67% of Japan is covered with forests, making it one of the
countries with the largest percentages of forest cover remaining. Because of this, there is
a large amount of vegetation cover at risk due to the industries of the East Asia region
(Ministry of the Environment- Japan, 1997). Japan itself does not release many acidic
pollutants into the air due to a lack of domestic coal reserves. The vast majority of the
pollutants come from Chinese industries. They are carried over by the westerly winds
and are then precipitated onto Japan. The Korean Peninsula is also in the path of China’s
industrial output, making acid rain a large concern in the area (See Figure 7).
Figure 1
www.owu.edu/.../geog_222/geog_222_lo/ geog_222_lo09.html
Figure 2
www.iclei.org/efacts/ acidfig3.gif
Figure 3
www.grida.no/db/maps/prod/ level1/70901.htm
Figure 4
badc.nerc.ac.uk/.../poster_heaven/ harrisond/slide5.html
Figure 5
www.cgrer.uiowa.edu/.../ Soil_sensitivity.html
Figure 6
www.cicete.org/newindex/page/ urban/page/Abbreviations.htm
Figure 7
www.nautilus.org/papers/energy/ streetsESENAY1.html
(Arrows added in)