Environmetal Soil Properties and Behaviour

Environmetal Soil Properties and Behaviour


DisciplinaControle e Remediação da Poluição dos Solos5 materiais18 seguidores
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groups because of the variety of situations and requirements for soil functions. 
A number of these will be described in the following summary discussion.
1.4.1 Natural in Situ Role
As we have seen in Figure 1.7, the geoenvironment is a natural resource base 
that features soil as its primary component, and the natural resources in the 
geoenvironment can be considered as the natural capital of the geoenviron-
ment. Figure 1.8 shows some of the principal ecosystems within the geoenvi-
ronment together with some of their major derivatives. The term ecosystems 
refers to a system where the various individual elements and organisms 
interact singly or collectively to the advantage or disadvantage of the whole. 
We consider the natural in situ role of soil to be one where the soil, which is 
in its natural state in the geoenvironment, functions without human or any 
Geoenvironment Ecosystems
Urban ecosystem
Aquatic ecosystems
Physiographic ecosystems
Agro ecosystem
Forest ecosystem Habitat for fauna, biota, and
other microbial species
Soil as a resource material
Fuel and energy
Groundwater and aquifers
Metals, minerals, etc.
Building materials
Soil ecosystem
FIguRE 1.8
The soil ecosystem as part of some of the major ecosystems, resources, and features of the 
geoenvironment. Note that the physiographic ecosystems include, for example, coastal, alpine, 
desert, and arctic ecosystems.
20 Environmental Soil Properties and Behaviour
other external intervention. In this main group, two main subgroups and 
perhaps some other lesser subgroups stand out prominently:
\u2022	 Habitat for fauna, other biota, and microbial species. Loss of biodi-
versity is perhaps one of the best-known concerns in seeking active 
means for habitat preservation.
\u2022	 Growing medium for plants, trees, and flora. Agricultural activities 
that involve the use of soil amendments or control of insecticides 
and pesticides are not directly included in this main group. These 
activities are grouped under the next major group: in situ role of soil 
with external intervention.
\u2022	 Physical and chemical buffering system. Particular examples of these 
are the filtration capability, especially in transmission of groundwa-
ter to receiving waters, and contaminant partitioning or accumula-
tive capacity of soils in respect to transport of contaminants.
\u2022	 Groundwater storage and quality determination. Surface hydrology, 
hydrogeology, and the roles of aquifers and aquitards are particu-
larly significant.
\u2022	 CO2 sink. Soil, organic matter, plants, trees, and others are important 
players in the carbon cycle.
\u2022	 Heat sink and source for climate and air temperature control.
These groups and subgroups feature prominently in establishing ecosys-
tem functioning. By this, we mean the activities of flora, fauna, plants, biota, 
microorganisms, animals, and so forth within the community defined by 
the ecosystem. In the broader sense, we can define a functioning ecosystem to 
include biological, chemical, and physicochemical activities that are charac-
teristic of the type of ecosystem under consideration. The living organisms 
in a specific ecosystem represent the biodiversity in the ecosystem and are 
important in maintaining atmospheric composition and production of oxy-
gen by photosynthesis and fixation of CO2 and recycling of carbon, nitrogen, 
phosphorous, and other elements in the soil.
1.4.2 In Situ Role with Human Intervention
The subgroups describing the basic soil functions within this main group 
(and the next main group in Section 1.4.3) are by and large associated with 
the major activities and industries involved in the production of food, shelter, 
and clothing. These include
\u2022	 Growing medium\u2014The major activities and industries involved 
are agroindustries and other activities associated with production 
of raw material such as cotton and timber. What distinguishes 
this from the previous natural in situ role is the use of soil 
21Origin and Function of Soils
amendments and other technological aids designed to increase 
food and material production. In situ soil\u2013water relationships, 
physical and mechanical properties, and fluid transmissivity, heat 
conductance, and transmission are some of the more important 
considerations.
\u2022	 Foundation support and other ground engineering-associated sys-
tems\u2014Major activities and products include foundation support for 
structures and infrastructure, tunnels and buried structures, buried 
pipelines, and transmission lines. The major sets of concerns revolve 
around the physical, fluid transmissivity, and physicochemical and 
mechanical properties of the in-place soil.
\u2022	 Containment systems\u2014We include waste landfills, mine tail-
ings ponds, and repositories in the B, C, or D horizons in this sub-
group. The major functional requirements revolve around natural 
soil buffering potential capacity, contaminant accumulation, and 
hydraulic permeability. The processes involved in situ are similar to 
those described in wastewater natural treatment systems (the next 
subgroup).
\u2022	 Wastewater natural treatment systems\u2014Slow-rate treatment, rapid 
infiltration, and natural wetlands are some of the natural treatment 
techniques used. The in situ processes involved include physical 
actions such as sedimentation; chemical reactions such as oxidation-
reduction, ion exchange, and precipitation; and biological activities 
such as biological conversion and degradation.
\u2022	 In situ groundwater harvesting, hydrocarbon resource extraction-
exploitation, and related activities\u2014These include the various in 
situ means for extraction of heavy oil, storage systems, and carbon 
sequestration.
1.4.3 Soil as a Resource Material
The subgroups in this main group are perhaps the most varied of the three 
main groups. As in the previous main group, these subgroups are best 
associated with activities and industries involved in the production of food, 
shelter, and clothing. Some examples of these include
\u2022	 Engineering construction\u2014This subgroup includes the use of soil 
as a construction material in varied forms, for example, sand and 
gravel for Portland cement concrete and bituminous concrete, 
embankments, sub-bases, and buffer-barrier systems.
\u2022	 Mining industry (metal, mineral, aggregate, hydrocarbon resources, 
etc.)\u2014Examples include extraction of oil such as tar sands, metals 
(bauxite industry), minerals such as quartz, calcite, and clay miner-
als such as kaolinite, montmorillonite, and illite.
22 Environmental Soil Properties and Behaviour
\u2022	 Paper, packaging, and paint industry\u2014Paper coating, packaging, 
and paint pigment.
\u2022	 Pharmaceutical-cosmetic industry\u2014Laxatives and creams.
\u2022	 Miscellaneous\u2014Pottery, ceramics, oxidizing agents, catalysts, filter 
for UV emissions, thickeners, chalk, and so forth.
There are many more uses for soils other than the examples shown in this 
section. Suffice to say that the importance of soil, either in place of or as a 
resource material, cannot be underestimated. It is a living dynamic system 
and its properties and behaviour will inevitably change with time.
1.5 Concluding Remarks
We consider soil to be an important resource material that possesses a large 
variety of functions. Soil functionality is dependent on several factors and 
circumstances, some of which are controlled by natural forces and others by 
humans and their activities. In this chapter and in this book, we are concerned 
with the engineering properties and behaviour of soils. The brief discussion on 
soil formation (origin of soil) is designed to remind us about the importance of 
understanding where soil comes from because we need to appreciate that the 
properties and behaviour of a soil are intimately tied into its origin, and ulti-
mately, its composition. Readers interested in learning