Environmental Engineering Reference
In-Depth Information
even biotechnological intervention. Application of any of these techniques depends on
(a) the nature and scope of the perceived threat, (b) the resource being threatened and its
functions or use, (c) the predicted intensity and type of damage done to the resource by
the impact, (d) the extent of resource protection needed, and (e) the economic impact. In
Figure 13.2 for example, assuming the absence of noxious gases and airborne particles, the
perceived source of threat is represented by the pesticides, insecticides, and other surface
contaminants that will move toward the river and also iniltrate into the ground during
periods of precipitation. The resources being threatened are the river, surface layer soil,
and the unconined aquifer. Assuming that the river and the unconined aquifer serve as a
drinking water sources, and further assuming that the soil is an agricultural soil resource,
the need and extent of protection required for these resources will be evident.
13.4 Water and Soil Quality Indicators
The discussion in this section extends the discussion on indicators in Section 9.2 of Chapter 9.
Figure 9.1 in Chapter 9 depicts the role of indicators in the situation created by precipitation
falling through airborne noxious gases and particulates. The water and soil quality indica-
tors identiied as monitoring targets include both system status and material performance-
or material property-status types. Water quality indicators and soil quality indicators are
essentially material property-status indicators. They are meant to indicate the quality of
the material (water or soil). The quality of the material under consideration or analysis is
established with speciic reference to its intended function. In regard to soil quality, for
example, we have seen from the previous section that the classic deinition developed for
agricultural use needs to be broadened to encompass the use of soils for various other pur-
poses—from waste management to building supplies and construction. This is also true
for water quality indicators. The range of usage starts from the top with drinking water
standards setting the height of the water quality bar. At the low end of water usage would
be water for agricultural purposes and other similar functions. Indicators for all the vari-
ous functions of both water and soil would vary both in form (type) and detail.
There are several levels of speciicity (i.e., levels of detail) in prescription of water quality
and soil quality indicators. These depend on (a) the intended function and management
goals, for example, drinking water usage or irrigation purposes, (b) ability to obtain all the
necessary data sets, (c) available and applicable remedial and/or corrective technological
capabilities, (d) scale and risk tolerance, and (e) economic factors. Perhaps the overriding
factors in all of these are
management goals
and
risk tolerance
.
13.4.1 Quality and Index
In Figure 13.3 and in the previous section, we talked about soil quality index (SQI) as a
measure of soil quality. Similar to the different intended functions for water and soil, deter-
mination of soil quality index (SQI) and water quality index (WQI) will also depend on
many of the same factors described in the preceding paragraphs. Development of indices
requires full consideration of the many different properties and inluences that ultimately
combine to produce the material status. Since this is a dynamic process dependent on
applications or processes being applied to the soil, internal soil reaction rates and elapsed
time, the indices will also vary in accord with circumstances and time. Quantiication of
Search WWH ::
Custom Search