RECLAMATION OF A BARE INDUSTRIAL-AREA CONTAMINATED BY NONFERROUS METALS - PHYSICOCHEMICAL AND BIOLOGICAL EVALUATION OF THE DURABILITY OF SOIL TREATMENT AND REVEGETATION

In 1990, 3 ha of a highly metal polluted acid sandy soil at the site o f a former pyrometallurgical zinc smelter was treated with a combinati on of beringite and compost, beringite is a substance that has a stron g metal immobilization capacity. After soil treatment and sowing of a mixture of metal-tolerant Agrostis capillaris and Festuca rubra, a hea lthy vegetation cover developed. Five years later, an evaluation was m ade of soil physico-chemical parameters, potential phytotoxicity, flor istic and fungal diversity and mycorrhizal infection of the plant comm unity. Phytotoxicity was shown to be maintained at the low level obser ved immediately after soil treatment. The water-extractable metal frac tion of the treated soil was up to 70 times lower compared to the non- treated soil. The vegetation was still healthy and regenerating by veg etative means and by seed. Diversity of higher plant species and sapro phytic fungi was extremely low in the untreated area due to the high s oil toxicity and the absence of metal tolerant ecotypes of plants and fungi. On the treated soil, in contrast, the species richness of highe r plants was much higher; several perennial forbs which are not noted as metal tolerant had colonized the revegetated area. Most of these sp ecies belong to mycotrophic families so that the presence of a mycorrh izal network in the soil promotes their establishment. The ubiquity of the mycorrhizal fungi in the roots showed that a functioning ecosyste m was establishing. In non-treated soil, the mycorrhizal infection rat es of the roots were consistently lower during the whole growing seaso n. (C) 1997 Elsevier Science Ltd.