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Enzymes in Tropical Soils 149

reported that the accumulation of Cu in plant tissues followed the order: roots,
shoot, and leaves.
The negative effects of heavy metals on the populations and activities of soil
microorganisms are not always unbeneficial. Mathur and Sanderson (1980)
suggested that heavy metals were possible to be used to restrain the
mineralization of organic soils. Copper, for example, may restrain the
mineralization and subsidence of some organic soils. The Cu element may
inactivate particular extracellular soil enzymes which normally facilitate the
biochemical oxidation of nonhumic soil organic matter. These soil enzymes may
include cellulase, amylase, lichenase, and lipase.

40

30
Plant Pb (mg kg -1 ) 20

10

BDL
0
Brocolli Cabbace Lettuce Leaves Lettuce 1 Lettuce 2

Fig. 9.13. Lead uptake into some vegetables in a high-level Pb-Contaminated soil (BDL
Below Detection Limit; Redrawn from Boon and Soltanpour, 1992).

Important Questions

1. Explain the effects of contaminant heavy metals on soil microorganisms,
macroorganisms, and plant roots!

Abdul Kadir Salam - 2014