Abstract
ABSTRACT Soil compaction and soil contamination are two common causes of land degradation on sites reclaimed after surface coalmining. Since land degradation is more easily prevented than cured, soil quality standards designed to focus land reclamation agencies on potential problems, supported by a system of sustained post-project land quality inspection and enforcement, may be the best route to underwriting the long term productivity of reclaimed lands. This paper opens discussion on the determination of appropriate measures of soil quality. It has three foci: soil physical structure, soil acidity, and soil contamination by heavy metals. It is suggested that successfully reclaimed land should have soil bulk densities that do not exceed 1.6 g/cm3 within 50 cm of the surface and 1.8 g/cm3 within 100 cm. Further, successfully reclaimed lands should have a soil pH which does not exceed the bounds pH (3.0) 3.5 - 8.5 (9.0) within 150 cm of the soil surface. Trigger concentrations for the recognition of heavy metal contamination are suggested. Particular attention should be given to the metals most frequently associated with human health problems: cadmium, lead, and to a lesser extent arsenic, mercury, and radionuclides such as uranium. Since many problems associated with soil decline build up over time, it is proposed that these conditions should obtain through inspection tests conducted at reclamation, then 10 and 20 years subsequently. It is emphasised that all of the guideline levels proposed are arbitrary. The inter-relationships between bulk density, soil acidity, heavy metal contamination, and other aspects of the soil system are complicated and, in most cases, not entirely determined by the research community.
Published Version
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