The Phytoremediation Potential of Local Wild Grass Versus Cultivated Grass Species for Zinc-Contaminated Soil

Abstract

The aim of the study was to compare the phytoremediation potential of cultivated grasses with local wild grass for soil contaminated with zinc. Two pot experiments were carried out on soil artificially contaminated with Zn. Four species of cultivated grasses were used as test plants: Poa pratensis, Lolium perenne, Festuca rubra, Festuca pratensis, and one wild, native grass: Deschampsia caespitosa. Wild grass seeds were collected from soil contaminated with heavy metals near a zinc smelter. The phytoremediation potential of grasses was determined on the basis of the tolerance index (TI), bioaccumulation (BF), and translocation (TF) factors. Differences were found between the species in the reduction in the shoot and root biomass with increasing soil contamination with Zn. The tolerance of the studied grasses to excess Zn in the soil was in the following order: D. caespitosa > L. perenne > F. rubra > F. pratensis > P. pratensis. In addition, there were differences in the accumulation and distribution of Zn between the roots and shoots, which is related to the different defense mechanisms of the studied grasses against Zn phytotoxicity. Of the five grasses tested, the highest phytoremediation potential was shown by D. caespitosa. This grass had a significantly higher tolerance to Zn and a lower transfer of Zn from the roots to shoots than the other cultivated grasses tested. All four cultivated grasses can be useful for phytostabilization because they accumulated Zn mainly in the roots and limited its translocation to the shoots. Unlike wild grass seeds, cultivated grass seeds are readily available commercially and can be used for the phytoremediation of HM-contaminated sites.