Vol. 32 – 2006 - Ecologia Mediterranea

concentration. The pH has been measured
also in soils and tailings.
Soil and plant samples were air-dried. Samples
of soil have been sieved at 2 mm mesh
and have been grounded carefully. Plant samples
have been grounded and transferred into
small bottles and oven dried at 60 oC until a
constant weight has been reached. Samples
(c.a. 2 g) were then calcinated in an oven at
460 oC after stepwise increase of temperature
(120, 240, 350, and 460 oC). Soil and plant
tissues were digested by concentrated acid
solutions (1 ml nitric acid 70% + 10 ml fluorhydric
acid) at about 120 oC. After drying,
perchloric acid was added (5 ml for plant tissues
and 10 ml for soil) and evaporated at 160
oC. After drying, minerals were dissolved in
nitric acid 70% (1 ml) and hydrochloric acid
38% (3 ml). Solutions were filtered and volume
was completed with deionised water
(H2O MQ). Quantification was performed
using ICP-AES (Inductive Coupled Plasma-
Atomic Emission Spectroscopy). Each sample
was analyzed in triplicates.
ecologia mediterranea – Vol. 32 – 2006
Heavy Metals in Tailings,Soils and Vegetation of an Abandoned Lead Mine Land in Morocco
Figure 2 – Zaida mine tailings (a: tailings, b: nearby the barrens, c: 50 m, d: 200 m and e: 1000 m away from the tailings).
b
Acidity in soil and tailings samples was measured
using an electrode pH meter (soil to
water ratio was of 1/2.5) according to standard
procedure (Lean 1982).
Results
a c
d e
Mean, maximum, and minimum concentrations
of heavy metals in soils, tailings and
plant species as well as pH, are summarized
in Table 1. These data showed higher concentrations
of heavy metals nearby the piles
of tailings and by their surroundings.
High concentration of lead was found in the
tailing while the concentration of this pollutant
remained lower at the place where the
plants were collected. For both plant species,
concentration remained higher in the root than
in the shoots. As far as aerial parts of the
plants were concerned, lead concentration
was slightly higher in Artemisia herba-alba
than in Stipa tenacissima.
87