Environmental Engineering Reference
In-Depth Information
Although it is beyond the scope of this topic, it should be mentioned that ground-
water plays an important role in energy balances, since water has a high energy
storage capacity. In many parts of the world, nowadays aquifer thermal characteris-
tics are used, mainly in terms of thermal energy storage in the summer time for the
purpose of using this energy later for heating buildings in the winter time.
17.2.2 Ecological Habitat Function
Analogous to the upper soil layer, the water-saturated deeper soil layer is the habitat
for many organisms, including widely differing species. Since there is no gas-filled
pore phase present in aquifers - so consequently oxygen is scarce - these organisms
have a totally different origin. Actually, from an ecological perspective, it is not the
groundwater but the
organisms
residing in the groundwater and the corresponding
Ecological Services
that are the protection targets.
In the European Water Framework Directive (WFD) it is stated that a good eco-
logical status of a groundwater body must take into account the requirement that the
chemical quality of groundwater must not endanger in any significant way terrestrial
ecosystems that depend directly on the groundwater body (European Commission
2008
).
Compared to the research efforts focused on ecological processes in the upper
soil, not much research has been performed on ecological processes in the ground-
water. However, since the 1990s the increased interest in
Natural Attenuation
in
groundwater, that is, degradation and dilution of organic contaminants as an often
cost-efficient remediation technique, has led to numerous studies on groundwater
ecology. As a consequence, anaerobic degradation is much better understood today.
Considering the same arguments as advanced for the protection of organisms in
the top soil layer, that is, the intrinsic significance of
Biodiversity
, along with ethi-
cal, spiritual and religious principles (see
Section 13.4.2
), ecological protection for
groundwater is essential. Also analogous to the soil compartment, the protection
of
Ecosystem Services
in the groundwater is of the utmost importance from a func-
tional point of view. The organisms in the groundwater also play a role in carbon and
nutrient cycling, although their role is not as immense as it is for the soil ecosystem
in the upper soil. Probably the most important function for groundwater is the so-
called 'cleaning function' (see Section
17.5.2
). Given the enormous developments
in the possibilities for practical use of Natural Attenuation in the aquifer, the role of
the aquifer ecosystem is highly appreciated, today.
17.2.3 Intrinsic Value
For decades, there has been an on-going, interesting discussion concerning the
intrinsic value
of groundwater. Although most humans approach the relevance of
groundwater from a functional perspective, there indeed may be less rational argu-
ments for caring about groundwater protection. From a spiritual perspective, for
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