Strategies for Covering Fly Ash Dumps with Plant Species Suitable for Phytostabilization

Abstract

In the context of the revegetation of fly ash dumps, the strategy chosen is very important in order to obtain a vegetal layer that quickly and efficiently covers the fly ash dump, as well as, to allow the wildlife habitat development. The strategy must include: adequate treatments by incorporating fertilizer and amendments, as composts and modified indigenous volcanic tuff; selecting plant species and agricultural work in accordance with geographical and weather conditions. Our in situ experiment on a lignite fly ash dump was performed in the fall during the seeding period of Festuca arundinacea and Onobrychis viciifolia species to provide the water requirement of plants, and consequently a quick and efficient development of plants, enabling them to resist later in the hot and drought days of summer. Among the seeding species, Festuca arundinacea adjusted more easily in the experimental variants. In this case, the treatment with biosolids and modified indigenous volcanic tuff can reduce the metal bioaccumulation, especially Pb (with 84-94%), Fe (with 53-63%) and Cu, Cr and Ni (between 12-53%). The other plant species did not tolerate the unfertilized fly ash. The fertilizer and modified indigenous volcanic tuff provided establishing conditions for the plant supplying the nutrients. Metal transfer to aerial tissues was reduced compared to control by 29.5-59.3% in the case of Cu, Cr, Ni and ranged 50-66% for Pb. Limiting the transfer of heavy metals in plant tissues is in accordance with a healthy habitat for the wildlife.

Keywords

• heavy metals
• vegetal layer
• metal-tolerant plant species
• bioaccumulation