Environmental Engineering Reference
In-Depth Information
While small amounts of metals are considered essential for the survival of many organ-
isms, large quantities are often toxic (Chapter Eleven). Few terrestrial and aquatic species
are known to be naturally tolerant of heavy metals, although some have adapted over time.
Many i sh are highly sensitive to even mildly acidic waters and cannot breed at pH levels
below 5. Some may die if the pH level is less than 6 (Ripley et al. 1996). In general, the
number of plant and animal species decreases as the aqueous concentration of heavy met-
als increases. Some taxa are known to be more sensitive to the presence of heavy metals.
This is particularly the case for species living in freshwater aquatic habitats. For example,
salmon species are particularly sensitive to increased concentrations of copper (Kelly 1998).
Furthermore, juvenile i sh are more sensitive than adult i sh, and the presence of heavy
metals may affect the critical reproductive and growth stages of i sh.
Water Balance
Mining invariably inl uences the local water balance and sometimes even the regional
water balance. Whether these impacts are felt and become important depends on the cli-
matic setting, the local hydrology, and the type of mine. Changes in the local water balance
are the direct result of changes in landform, land cover, and from water usage by the mine.
Mine dewatering also changes the water balance.
Mine closure itself can affect the water balance, a situation which may be overlooked in
the environmental assessment process. The environmental effects of groundwater rebound
after shutting down pumps can be signii cant. Furthermore, a new ecological equilibrium
may have developed, in response to the changed water balance during mine operation.
This is the case along the Erft River in North Germany: for more than 20 years the river
received most of its water from the dewatering pumps of the large coal strip mining oper-
ations close by.
The environmental effects of
groundwater rebound after
shutting down pumps can be
signifi cant.
13.4 AIR QUALITY AND CLIMATE CHANGE
As with most industrial activities, mining affects air quality. The most obvious impacts
are from the generation of dust and combustion gases. Considering the entire life-cycle of
mine products, however, the relationship of mining and air quality is more complex than
these obvious impacts.
Atmospheric and noise pollution are addressed in various parts in this text and there-
fore are only briel y addressed in this chapter. The emerging issue of mining's contribution
to climate change is dealt with in greater detail.
Atmospheric Pollution
Mining operations can affect air quality in many ways. An air emissions inventory as illus-
trated in Figure 2.7 in Chapter Two is useful in addressing atmospheric pollution issues.
Material movement, stationary sources, and fugitive emissions are the three main sources
of air quality degradation.
Land transport is one of the major sources of atmospheric emissions. Emissions from
land vehicles are most often considered in terms of the exhaust from fuel combustion.
However, dust generated by land transportation is often the main source of air pollution.
Combustion of petrol or diesel fuel leads to the production of exhaust gas containing a
Dust generated by land
transportation is often the main
source of air pollution.
 
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