Civil Engineering Reference
In-Depth Information
Table 2.2:
Natural occurrence of elements in the accessible part of the Earth's
crust
Amount (g/ton)
Elements
Greater than 100 000
O, Si
100 000-10 000
AI, Fe, Ca, Na, K, Mg
10 000-1000
H, Ti, P
1000-100
Mn, F, Ba, Sr, S, C, Zr, V, CI, Cr
100-10
Rb, Ni, Zn, Ce, Cu, Y, La, Nd, Co, Sc, Li, N, Nb, Ga, Pb
10-1
B, Pr, Th, Sm, Gd, Yb, (Cs, Dy, Hf), (Be, Er), Br, (Sn, Ta), (As, U), (Ge, Mo,
W), (Eu, Ho)
1-0.1
Tb, (I, Tm, Lu, TI), (Cd, Sb, Bi), In
0.1-0.01
Hg, Ag, Se, (Ru, Pd, Te, Pt)
0.01-0.001
(Rh, Os), Au, (Re, Ir)
Source: Hägg 1984
environment. Table 2.2 shows the natural occurrence of certain elements in the
accessible part of the Earth's crust. Elements of approximately the same concen-
tration are placed within brackets in order of their atomic number.
Types of pollution
Environmental poisons
Toxic substances that are heavily decomposible and/or bio-accumulative, which
means that they concentrate themselves within nutrient chains. In addition to the
heavy metals, it is important to consider organic poisons. Many of these sub-
stances are spread by air to the most remote places, and they are in the process
of becoming concentrated in ground water in highly-populated areas. Many of
them are thought to have environmentally dangerous side effects.
Dust
Dust is produced during the extraction of materials, various industrial processes
and through incomplete combustion of solid fuel and oil. It is also caused by
building materials such as mineral wool and asbestos. Dust can be chemically
neutral or carry environmental poisons.
Substances that reduce the ozone layer
These are mainly the chlorinated fluorocarbons.
