Environmental Engineering Reference
In-Depth Information
soils near a copper smelter in central Chile (Ginocchio
1997
,
1999
,
2000
) have also
been performed by local and international scientists but they have not revealed
further metal-tolerant plants.
In the last decade, however, increasing research has occurred in the Region
in order to identify metallophytes. For example, scientific explorations per-
formed in two different areas of northcentral Chile have recently resulted in
an important number of new descriptions of copper-tolerant plants native and
endemic to the country. The first study was carried out in a large area of north-
central Chile that has a semi-arid Mediterranean climate type (the Coquimbo
Region). Due to historic copper/gold mining a large number, 395 (SERNAGEOMIN
1989
,
1990
), of abandoned tailings storage facilities (TSF) are scattered through-
out the area. Furthermore, metal-polluted soils and natural mineralised areas
are also quite common inside the area. The results showed that 76 abandoned
TSFs have been colonised by 106 local plants, 71% being native and endemic to
Chile. In laboratory tests, 33 species were found to be copper-tolerant. A second
study was performed in the Yerba Loca Natural Sanctuary (YLNS), a well-known
high-alpine valley in central Chile, for its historic surface water anomalies. The
YLNS (33
S60
W) is located c. 60 km east of the city of Santiago and west from
the south edge of the R´o Blanco-Los Bronces-Yerba Loca Cu-Mo deposit. A large
porphyry Cu deposit (
40 km
2
) with secondary formation of tourmaline and
Cu-Zn-Mo sulphides thus exists at high elevations of the basin. Mineral deposits
have long influenced surface water quality of streams in the area which
broadly differs from dilute waters described for the high Andes in central
Chile, particularly in terms of pH, sulphate content and mineral concentra-
tions. For example, the main stream along the YLNS has acidic pH (4.1 5.3) and
high sulphate (
>
150mg L
1
) and metal content waters (3.6 9.1 mg Cu L
1
and
0.2mg Zn L
1
). These marked gradients in surface water chemistry may have
an important role in structuring plant communities at the YLNS, particularly in
meadows, as acidic and metal-rich waters are highly toxic to most plant species,
thus resulting in tertiary heavy-metal vegetation. In harsh water quality environ-
ments only a limited suite of species is adapted to survive and reproduce on high-
alpine meadows at the YLNS. Indeed, Festuca purpurascens (Poaceae), Gaultheria
caespitosa (Ericaceae), Calamagrostis chrysostachya (Poaceae) and Empetrum rubrum
(Empetraceae) are abundant in habitats with acidic and metal-rich waters,
while Carex macloviana (Cyperaceae), Patosia clandestine ( Juncaceae) and Erigeron
andicola (Asteraceae) are abundant in habitats with diluted waters. In the YLNS,
a total of 30 potential metallophytes have already been identified but further
laboratory testing for metal tolerance is under way.
>
Information from geobotanical surveys
Large-scale mining in Latin America has employed traditional methods of
exploration for minerals based on geology (rock colouration), radiometrics,
