Geography Reference
In-Depth Information
cities can be particularly high because of intense
motor traffic. The impairment, in effect a form of
weathering, of important urban buildings and
monuments is apparent in many of the world's
major cities. Building materials such as marble,
limestone and sandstone may be adversely affected,
and so too may metals. All suffer corrosion, which
disfigures the detail of architectural design, which
is costly to restore. According to McCormick
(1997),
c
. 2.5 cm of the Portland stone on St Paul's
Cathedral in London has been removed, although
the mechanical action of weather has also played a
role in this. Similar problems have occurred in
Stockholm, Sweden, where damage has defaced
the Royal Palace and the Riddarholm church. The
calcitic Gotland sandstone, of which both were
constructed in the eighteenth century, shows
evidence of crumbling and decay. This takes the
form of a crumbly, loose surface, gypsum and other
salt formation and discolouration.
There are also serious concerns about the
condition of many ancient monuments in modern
urban centres, as in Athens, Greece, including the
Parthenon on the Acropolis. These have been
constructed from limestone and are thus
susceptible to dissolution as the alkaline limestone
neutralises the acidic emissions. Ancient
monuments elsewhere have also been defaced by
acid rain, as Wilford (1996) reports in relation to
the Mayan ruins in Central America and in the
Yucatán peninsula of Mexico. The source of the
acid precipitation is oil refineries and uncapped
oil wells in the region, with an additional
contribution from tourist buses. Plate 3.1 shows
the damaged detail of the 'Nunnery' at Uxmal,
Mexico.
The high concentrations of sulphur dioxide in
many former Soviet cities must also be a cause of
considerable damage to the urban fabric. For
example, Shahgedanova and Burt (1994) report
that in 1988 sulphur dioxide emissions exceeded
1000 tonnes per year in twenty-seven towns/
cities. In Noril'sk, in Siberia's Taimyr peninsula,
emissions were
c
. 2.2×10
6
tonnes, which
amounted to 12.4 tonnes per capita; the major
source is the copper-nickel smelters of the
Noril'sk Mining and Metallurgical Combine. The
Plate 3.1 Damage due to acid precipitation on the
'Nunnery', part of the Mayan complex at Uxmal, Mexico
(photograph: Dr M.D.Turnbull)
.
resulting damage to hinterland forests has
increased substantially since 1970, but urban
fabrics and human health will not have been
spared by such acute levels of pollution.
As in the case of lake and terrestrial ecosystems,
remedial measures must involve the diminution of
emissions through increased energy efficiency in
buildings and transport systems, and less
dependency on the car.
The impact of acid precipitation on human health
Air quality is recognised as an important factor in
human health, especially in relation to respiratory
diseases. However, acid precipitation may have
additional though indirect effects on human
health through its impact on soils and water
resources. In particular, heavy metals may be
