Page 231 - Plant-Based Remediation Processes

11 Flax (Linum usitatissimum L.) and Hemp (Cannabis sativa L.)... 223

Table 11.5 Content of metal elements in the seed of linseed (modified from Klein and Weigert
1987)
Seed content Range
Metal element (mg kg 1 DW) (mg kg 1 DW)
Lead (Pb) 0.216 0.005–7.560
Cadmium (Cd) 0.353 0.005–1.330
Mercury (Hg) 0.013 0.0005–0.110
Arsenic (As) 0.044 0.005–0.410
Chromium (Cr) 0.211 0.050–0.542
Copper (Cu) 11.184 4.000–18.300
Manganese (Mn) a 16.000–27.800
Nickel (Ni) a 0.720–2.200
Selenium (Se) 0.250 0.025–1.110
Zinc (Zn) 52.380 32.600–151.600
a
Mean value not presented due to low number of measurements (n ¼ 6)

(Straczynski and Andruszczak 1996; Jankauskiene 1998; Belopuhov et al. 2001),
majority of reports concentrated on Cd, less on Pb, Zn or Cu. Thus, the most
consistent data are available in Cd and also the attempts to make certain
generalisation/conclusions in this review have been derived mainly from Cd results.
Environment, as influenced by site and year, had the greatest effect on heavy
metal concentrations in seed and tissue in the field experiments. The concentration
of bioavailable soil Cd (in contrast to total Cd) is the key factor for Cd uptake by
flax and in the certain concentration interval it may be proportional to accumulated
Cd (Moraghan 1993). This factor mostly dominated over other factors, including
significant genotype differences in Cd uptake and accumulation. The content of
bioavailable metal element may represent only very small fraction of its total
content—e.g. in the case of Pb in industrially polluted soil it was 1.7 % (Grzebisz
et al. 1997a). Growing of flax in naturally metal–rich soils resulted in several times
higher accumulation as compared to sites with lower heavy metal content
(Schneider and Marquard 1996; Cieslinski et al. 1996; Grant et al. 2000). Cd
concentration in the seed of the same linseed line/variety several times differed
(up to sixfold) between various locations (Marquard et al. 1990; Schneider and
Marquard 1996; Cieslinski et al. 1996; Grant et al. 2000). Numerous experiments
used natural (geogenic) Cd soil concentrations (ca. 0.1–0.5 mg Cd kg 1 soil),
artificial increase of soil Cd concentration led always to significant increase (up
to 20-fold) of Cd content in flax tissues (Gaudchau and Marquard 1990; Heyn and
Janssen 1991;Bo ¨hm et al. 1992;Bo ¨hm and Marquard 1993a, b; Moraghan 1993;
Bjelkova et al. 2001). Cd accumulation in the seed sometimes overcame Cd soil
concentration, e.g. by one order of magnitude larger (Heyn and Janssen 1991).
Increased accumulation was mostly found on soils rich in nutrients, resulting at the
same time in higher yields (Marquard et al. 1990). Accumulation of Cd in the seed
was strongly related to the seed yield. Concentration and accumulation of Cd
increased with increasing seed yield, both across soil types and across treatments