Industrial Ecology and the Geoenvironment - Sustainable Practices in Geoenvironmental Engineering - page 121

Acid precipitation impact on the surface of the geoenvironment (including the receiving
waters contained in the land environment) is felt in several ways:
a. Soil quality: The increased soil acidity will release metal ions and other positive
ions bound to the soil particles, and also the structural ions such as aluminum.
The mechanism for such release is found in the ionic bonds formed between the
charged soil particles surfaces and the positive ions (metals and salts such as
Ca 2+ , K + , Na + , and Mg 2+ ). The sulfate and nitrate ions from acid precipitation act as
counterions and have the effect of releasing the sorbed cations. Weathering of the
silicate minerals will release the structural metals such as aluminum, manganese,
and iron. The release of the salts Ca 2+ , K + , Na + , and Mg 2+ will result in nutrient
depletion for plant growth and the release of aluminum especially will be harm-
ful to aquatic life and plant growth.
b. Biology of the forest: Reduction in rates of decomposition of the forest loor, dam-
age to roots and foliage, changes in respiration rates of soil microorganisms.
c. Water quality and aquatic habitats: Acidiication of lakes and rivers, deposition
of soil-released aluminum, species destruction, and alteration of food supply for
higher fauna.
Other not so evident land environment impacts from the mining-processing down-
stream industries are (a) use of nonrenewable mineral resources as source material for
the downstream industries and (b) excessive use of nonrenewable energy resources to
drive the various processes in production of the inal product. Except for the aggregate
and slab production industries, metal mining and processing downstream industries,
and the cement producing industries are heavy users of energy. Until alternative renew-
able energy resources become more available, these industries impact directly on the land
environment when land energy resources are used to fuel their many process require-
ments. Cement kilns are perhaps the best potential users of alternative energy sources
using recycled or recoverable materials. Because of the high burn temperatures required
in the cement kilns, municipal biowaste, and various kinds of combustible solid and liquid
wastes can be used as burn energy sources.
Land environment sustainability objectives of direct relevance to the metal mining and
processing downstream industries are (a) preservation or minimal use of nonrenewable
energy resources, (b) preservation or minimal use of metal-mineral resources, (c) elimina-
tion of smokestack emissions and airborne noxious particulates, and (d) 4Rs and nontoxic
and nonhazardous discharge of liquid and solid wastes. Figure 4.6 shows some of the ele-
ments that can serve to drive downstream industries toward sustainability goals. Industry
initiatives are needed for many of the elements shown, e.g., (a) better control on smoke-
stack emissions and airborne particulate discharge to eliminate deposition of particulates
and generation of acid precipitation, (b) more eficient use of metal-mineral resources to
produce more “yield,” (c) the use of the 4Rs (reduce, recover, reuse, and recycle) strategy
as part of the process eficiency technology, and (d) use of alternative renewable energy
sources to aid in reduction of consumption of nonrenewable energy resources. Chapter 9
gives a brief discussion of these initiatives. A full treatment of these industry initiatives is
not within the purview of this topic. There exists much concern and interest in the devel-
opment of these initiatives, and without a doubt, much is being done by industry to resolve
these issues.
The direct connections between the impacts shown in Figure 4.6 and the geoenvironment
are seen in terms of contamination of the land and water elements of the geoenvironment.