Bioacumulation capacity of Iris humilis

Abstract

The mineral composition of the plant mainly depends on two factors – the growing soil composition and/or the influence of the environment (especially anthropogenic factor). Availability of metal’s ions in soil for plant root is determined by element form, pH-value, etc. Some plants possessed ability to concentrate (bio accumulate) some macro- or microelements. The aim of this work was to examine ability of diff erent parts of Iris humillis plant (rhizome, above-ground vegetative part and flower) to bound metal ions from surrounding growing soil or environment. Th is process was expressed as Biological Absorption Coefficient (BAC) which was calculated as cplant part/csoil ratio where cplant part and csoil are concentration of selected element in different parts of plant i.e. in soil. Content of selected elements (potassium, phosphorus and nickel) in soil and plant was determined by ICP-OES method (including pre-digestion of samples) and expressed as mg/kg of dry matter. Determined concentrations of potassium, phosphorus and nickel in soil were 877.1 mg/kg, 352.2 mg/kg and 2.97 mg/kg respectively. Content of selected elements in different parts of I. humillis was as follow: rhizome (K- 1686.0 mg/kg, P- 474.2 mg/kg and Ni- 8.5 mg/kg), above-ground vegetative parts (K- 3033.1 mg/kg, P- 423.1 mg/kg and Ni- 0.29 mg/kg) and flower (K- 1461.4 mg/kg, P- 273.0 mg/kg and Ni- 0.12 mg/kg). According to results for BAC potassium was bioaccumulate in all plant parts since value of this factor was higher than 1 (BACrhizome= 1.92, BACabove-ground vegetative parts =3.46, BACflower= 1.67). Also, rhizome and above-ground vegetative part of I. humillis showed ability for bioaccumulation of phosphorus (BACrhizome= 1.35, BACabove-ground vegetative parts =1.20, BACflower= 0.78) while rhizome possessed high ability to concentrate nickel (BACrhizome= 2.86). The obtained results indicated that this Iris species possessed good ability for Ni-bonding through rhizome. It can be important for potential bioremediation use, since increased nickel concentration in the environment can be caused by some anthropogenic sources.