Plant Availability of Heavy Metals in Soils Previously Amended with Heavy Applications of Sewage Sludge

✍ Scribed by Hooda, P S; McNulty, D; Alloway, B J; Aitken, M N

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 256 KB
• Volume: 73
• Category: Article
• ISSN: 0022-5142
• DOI: 10.1002/(sici)1097-0010(199704)73:4<446::aid-jsfa749>3.0.co;2-2

✦ Synopsis

Plant uptake is one of the major pathways by which sludge-borne potentially toxic metals enter the food chain. This study examined the accumulation of Cd, Cu, Ni, Pb and Zn in wheat, carrots and spinach grown on soils from 13 sites previously amended with sewage sludge. Winter wheat, carrots and spinach were grown consecutively under Ðeld like conditions. The results showed that plant availability of heavy metals di †ered widely among the crop species. The accumulation of Cd, Ni and Zn in the plants showed the greatest increases compared to their background levels. The Cu and Pb accumulation in the plants grown on sludge-amended soils showed only small increases compared to those grown on uncontaminated soils. Multiple regression analysis of various soil properties showed that the surest way to control the accumulation of metals in food plants is by controlling their concentrations in the soils. Furthermore, soils with a non-acidic pH and a clayey texture tended to achieve better control of metal accumulation in food plants compared to those with an acidic reaction and a coarse texture. Metal concentrations in the plants generally correlated well with those extracted from soils in 0É005 M DTPA, 0É05 M EDTA-(Na) 1 M 2 , and 0É05 M

The EDTA, however, proved to be a more reliable NH 4 NO 3 CaCl 2 . and consistent test in predicting the accumulation of metals in the plants. The results also showed that liming soils to pH 7 e †ectively reduced the metal contents in carrots and spinach, but liming to pH 6É5 had little e †ect on metal concentrations in wheat grain.