ISSN:
1573-2932
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
Notes:
Abstract High Cd and Ni concentrations in sandy soils were built up in a field experiment, receiving an unusually metal-polluted sewage sludge between 1976 and 1980, at Bordeaux, France. The study evaluates the availability of metals and their after effects on maize at one point in time, the 8th year following termination of sludge application (1988). Plant parts (leaves, stalks, roots, grains) and soil samples were collected from plots which received 0 (Control), 50 (S1) and 300 Mg sludge DW ha−1 (S2) as cumulative inputs. Dry-matter yield, plant metal concentrations, total, and extractable metals in soils were determined. Metal inputs resulted in a marked increase in total and extractable metals in soils, except for extractable Mn and Cu with either 0.1 N Ca(NO3)2 or 0.1 N CaCl2. Total metal contents in the metal-loaded topsoils (0–20 cm depth) were very often lower, especially for Cd, Zn, and Ni, than the expected values. Explanation was partly given by the increases of metal contents below the plow layer, particularly for Cd at the low metal loading rate, and for Cd, Ni, and Cu at the high one (Gomez et al., 1992). In a control plot beside a highly metal- polluted plot, Cd, Zn, and Ni concentration in soil increased whereas the concentration of other metals was unchanged; lateral movement, especially with soil water, is plausible. Yield of leaves for plants from the S2 plot was reduced by 27%, but no toxicity symptoms developed on shoots. Yields of stalks for plants in both sludge-treated plots numerically were less than the controls but the decrease was not statistically significant. Cd and Ni concentrations increased in all plant parts with metal loading rate while Mn concentrations decreased. Leaf Cd concentration in plants from sludge-treated plots (i.e. 44 and 69 mg Cd kg−1 DM for S1 and S2) was above its upper critical level (i.e. dry matter yield reduced by 10%: 25μg Cd g−1 DM in corn leaves, Macnicol and Beckett, 1985). Yield reduction at the high metal-loading rate was probably due to 3 main factors: Mn deficiency in leaves, the accumulation of Ni especially in roots, and the increase of Cd in leaves. The amount of metal taken up by plants from the control plot ranked in the following order (mole ha−1): Fe(22)≫ Mn(7)〉Zn (5.6)≫Cu (0.7), Ni (0.6), Cd (0.4). For sludge-treated plots, the order was (values for S1 and S2 in mole ha −1): Fe (16, 15)〉Zn (7.9, 7.7)〉Ni (4.3, 4.7)〉Cd (1.9, 2.1)〉Cu (1.0,1.2), Mn (1.5, 1.1). Zn and Cd had the greatest offtake percent from the soil to the above ground plant parts. Cd or Ni uptake by maize were correlated with extractable metals by unbuffered salts (i.e. 0.1 N Ca(NO3)2 and 0.1 N CaCl2). It is concluded that part of the sludge-borne Cd and Ni can remain bioavailable in this sandy soil for a long period of time (e.g. 8 yr) after the termination of metal-polluted sludge application.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00482941
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