Environmental Engineering Reference
In-Depth Information
families. There are other cases of contamination, however, that are indirectly caused by
man-made activities. A good example of this is leaching of exposed sulide ores and rocks
(Chapter 5) and waste piles in landills will also produce polluted recharge water. Other
causes of contamination of water resources have been discussed in Chapter 3.
Soil fatigue and loss of soil quality can occur from natural causes such as those leading to
aridiication and desertiication. Long periods of rainfall deprivation leading to aridiica-
tion and inally desertiication are conditions of nature. Desertiication can also result from
a prolonged process of degradation of a once-productive soil. The root causes for desertii-
cation are deemed to be a complex mix of various degradative actions. The present concern
is soil fatigue and loss of soil quality from human activities leading to poor forest and
agricultural management and intensive forestry and agricultural practice are conditions
that will eventually render the soil useless for production of plants and crops. In respect
to agriculture, as we have noted in Chapter 2, soil quality is a determinant of the capability
of a soil to sustain plant and animal life and their productivity, and any diminution of soil
quality will impact on its capability to provide the various functions such as plant and ani-
mal life support, forestry and woodland productivity, and will undoubtedly result in the
loss of biological activity and biodiversity, and depletion of nutrients in the soil.
We should note that soil quality as a measure of the functionality or capability of a soil
is not conined exclusively to the agricultural usage. Soil can also serve other kinds of
functions. These include (a) containment and management of wastes and waste streams,
(b) resource material for production of building blocks, and (c) sub-base support for struc-
tures and facilities. The determinants for soil quality for these types of functions will dif-
fer from the classic deinition, which was developed for agricultural use. This is discussed
further in Section 13.3.
13.3.2.2 Management for Sustainability Goals
For sustainability management of the land environment and particularly of the water
and soil resources, a necessary requirement is for recharge materials and processes to be
devoid of contaminants and other detrimental and degrading agents. This is particularly
acute for reuse and recycle of process water. At all times, the quality of water and soil need
to be maintained and even improved. For this to occur, we need to establish water and soil
quality indices and to further establish baseline values for these indices. These indices
will require analyses involving indicators—both status and material indicators—as will
be discussed in more detail later in this chapter.
• Recharge of Water Resources : The sources of natural recharge of receiving waters
and groundwater are direct precipitation (rain, snow, hail, and sleet) and snow-
melt delivered as percolation and iniltration. The chemistry of precipitation that
deines the quality of the precipitation is a function of the nature, chemistry, and
concentration of airborne particulates through which precipitation occurs. As
noted in Chapter 10, the noxious substances in the atmosphere derived from man-
made activities include NO x (nitrogen oxides), SO 2 (sulfur dioxide), CO (carbon
monoxide), Pb and other metals such as Al, As, Cu, Fe, La, Mg, Mn, Na, Sb, V,
and Zn, as airborne particulates, VOCs (volatile organic compounds), aromatic
hydrocarbons such as benzene, toluene, and xylene and PAHs such as anthracene
and naphthalene. The same holds true for the chemistry of the snowpack that
serves as the storage for recharge as snowmelt. Thus, for example, Nanus et al.
(2003) reports that high-elevation areas in the Rocky Mountains annually receive
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