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Rivista di Biologia Molecolare e Biotecnologie

Indexed/Abstracted in: EMBASE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 0,246

Periodicità: Trimestrale

ISSN 1120-4826

Online ISSN 1827-160X


Minerva Biotecnologica 2001 March;13(1):19-26


Beneficial ­effects of the ­growth of met­al tol­er­ant ­grass on bio­log­i­cal and chem­i­cal param­e­ters in cop­per- and ­zinc con­tam­i­nat­ed ­sandy ­soils

Bouwman L. A. 1, Bloem J. 1, Romkens P. F. A. M. 1, Boon G. T. 1, Vangronsveld J. 2

1 Alterra, Green World Research, P.O. Box 47, 6700 AA Wageningen, The Netherlands;
2 Limburgs Universitair Centrum, Universitaire Campus, B-3590, Diepenbeek, Belgium

Background. Growth of met­al tol­er­ant grass­es on two ­sandy ­soils con­tam­i­nat­ed ­with ­either cop­per (­arable ­soil) or ­zinc (­bare ­soil) result­ed in a sig­nif­i­cant reha­bil­i­ta­tion of ­soil chem­i­cal and bio­log­i­cal prop­er­ties.
Methods. In the ­arable ­soil (Wageningen, the Nether-lands), cop­per con­tam­i­na­tion ­caused a sig­i­nif­i­cant reduc­tion of ­crop ­growth but the ­growth of a Cu-tol­er­ant varie­ty of Agrostis capil­lar­is result­ed in an ­increase in ­soil pH, DOC and dis­solved Ca con­cen­tra­tions ­which ­caused a sig­nif­i­cant reduc­tion of the ­free Cu2+ activ­ity ­from initial­ly tox­ic (­between 10-5 to 10-6 M) to non-tox­ic lev­els (­between 10-7 to 10-10 M). Also, bac­te­ri­al ­growth and num­bers of bac­te­riv­or­ous nem­a­todes, ­which had ­been strong­ly sup­pressed as a ­result of ­high Cu lev­els (170 mg·kg-1) in com­bi­na­tion ­with a low ­soil pH (4.7), nor­mal­ized as an ­effect of ­grass ­growth. In the extreme­ly Zn-pol­lut­ed ­bare ­sandy ­soil of an old ­zinc smelt­er ­site (Maatheide, Belgium) ­with Zn lev­els up to 16.000 mg·kg-1, bio­log­i­cal and chem­i­cal param­e­ters ­also recov­ered due to the ­growth of Zn-tol­er­ant varie­ties of Agrostis capil­lar­is and Festuca ­rubra dur­ing a reha­bil­i­ta­tion ­study on 3 hec­tares. To ­reduce met­al avail­abil­ity, the experi­men­tal ­field on the Maatheide ­site was treat­ed ­with beringite (modified aluminosilicate originating from fluidized bed burning of coal refuse), and com­post­ed munic­i­pal ­waste. A mix­ture of the two ­grass varie­ties was ­sown ­which result­ed in a ­well devel­op­ing ­grass cov­er with­in 4 ­months.
Results. The com­bi­na­tion of the ­reduced chem­i­cal avail­abil­ity due to addi­tion of berin­gite and the grad­u­al devel­op­ment of the veg­e­ta­tion, great­ly ­reduced the tox­ic­ity of met­als ­present in the ­soil solu­tion. Extractable ­amounts of Zn in a 0.01 M CaCl2 solu­tion ­decreased ­from 525 mg·kg-1 to 16 mg·kg-1 in the treat­ed ­plots ­which result­ed in the nor­mal­iza­tion of the ­below-­ground food­web as ­expressed by the num­bers and diver­sity of organ­isms and of meta­bol­ic func­tion­ing, ­such as bac­te­ri­al ­growth and ­soil res­pi­ra­tion. Under ­grass, approx­i­mate­ly 109 bac­te­ria, 6·104 pro­to­zoa, 5 m fun­gal ­hyphae and 27 nem­a­todes ­were ­found per ­gram of dry ­soil, ­which was ­between 10 to 100 ­times high­er ­than ­those ­obtained in the non-treat­ed ­plots. Also the func­tion­al diver­sity of the ­soil bac­te­ri­al pop­u­la­tions, meas­ured as the capac­ity to metab­o­lize a num­ber of dif­fer­ent sub­strates, had ­almost dou­bled ­after ­soil treat­ment.
Conclusions. Chemical (i.e. addi­tion of berin­gite) and bio­log­i­cal (­growth of met­al resis­tant ­crops) manip­u­la­tion of ­soil result­ed in a ­marked ­decrease of the tox­ic­ity of met­als ­present in the ­soil and an ­increased avail­abil­ity of ­food for ­soil organ­isms ­that had ­been ­reduced to pov­er­ty for ­many ­years. Consequently, the ­soil ­food ­webs ­were ­restored.

lingua: Inglese


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