Environmental Engineering Reference
Agriculture and industry: the protection of littoral areas from erosion
will allow better planning for the distribution of productive activities as
well as obviate problems with saltwater intrusion into water wells.
Transportation and trade: blocking the sea from advancing will prevent
instability risks for railways and roads, as well as reduce silting prob-
lems in harbors and marinas, thus favoring touristic and commercial
Indicators for Air and Water Quality
Numerous definitions for indicators are mentioned in the statistical, eco-
nomic, and environmental literature, though everyone agrees that an indi-
cator provides a synthetic representation of reality through a value or
parameter, and the information deriving from such a value is wider than the
value itself and should be related to the type of user and the context in
which it is situated.
Specifically, the indicators used to monitor the qualitative state of the
air are generally those pollutants that have short-term effects on human
health, such as carbon monoxide (CO), nitrogen dioxide (NO 2 ), sulfur diox-
ide (SO 2 ), ozone (O 3 ), suspended particulates (suspended particulate mat-
ter, PM 10 or PM 2.5 , depending on the dimensions), benzene (C 6 H 6 ), and
heavy metals. These indicators are based on data regarding the concentra-
tion of atmospheric pollutants measured at monitoring stations distributed
throughout the territory; the control of these parameters is regulated by leg-
islative decree no. 155/10, which imposes the concentration limits of the
pollutants in the atmosphere.
This type of direct analysis should, however, be integrated with a type
of monitoring known as biomonitoring, which uses living organisms; for
the air component, the biological indicators most often used are epiphytic
lichens, making use of the symbiotic associations between sac fungi, uni-
cellular green algae, and cyanobacteria, which manage to accumulate
appreciable levels of atmospheric contaminants (metals, radionuclides,
chlorinated hydrocarbons, fluorides, and so on) that are difficult to meas-
ure in air samples. In addition, lichens, as organisms which grow very
slowly, reflect with high precision the average pollution that an area was
exposed to over a period of several years. The response of lichens to atmos-
pheric pollution is quantified using the index of atmospheric purity devel-
oped by De Sloover and LeBlanc, which provides a quantitative estimate of
the level of atmospheric pollution based on the number, frequency, and tol-
erance of lichen species present in the area considered.
Relative to the quality of surface waterways , legislative decree no.