Bio-accumulation of As(III) and As(V) species from water samples by two strains of Aspergillus niger using hydride generation atomic absorption spectrometry

Abstract

The bio-accumulation ability of two strains of Aspergillus niger was studied in various synthetic media containing inorganic single-species As(III) and As(V) solutions and their admixtures and mining water with high As content in order to study the extent of bio-accumulation of the As species by the fungi. The AN1 A. niger strain, which served as a reference, was isolated from the Eutric Fluvisol soil (pH H₂O/KCl 7.7/7.4) originating from an uncontaminated area near Gabčíkovo (Southwest Slovakia). The AN3 A. niger strain was isolated from the bottom sediment with a natural content of As 363 mg kg⁻¹ (pH H₂O/KCl 5.27/4.8) collected from the Blatina stream running from abandoned antimony mines near Pezinok (West Slovakia). Samples of fungi biomass following bio-accumulation experiments were acid-decomposed in an autoclave under elevated temperature and pressure and used for total inorganic arsenic (As) determination. After 24 h of bio-accumulation in a solution containing 10 µg L⁻¹ As(III), the AN1 strain showed to be more efficient transforming 73% of As(III), in comparison with the AN3 strain by which 38% of As(III) was bio-transformed. On the other hand, the AN3 strain demonstrated greater capacity to retain in its mycelia 17% of As from a solution containing 10 µg L⁻¹ As(V) as compared with less than 10% of As(V) accumulated in the mycelia of the AN1 strain. Continuous hydride generation atomic absorption spectrometry (HG-AAS) was used for simple, rapid, sensitive and accurate determinations of total inorganic As and As(III). The accuracy of the method for the determination of As(III) was evaluated by analysing spiked synthetic and natural river waters. Recoveries of 96–102% of spikes were obtained. Limits of detection (3σ-criterion) for total inorganic As determination and As(III) determination were 0.22 and 0.28 µg L⁻¹, respectively.

Keywords:

• total inorganic arsenic
• arsenite
• speciation
• water
• Aspergillus niger
• hydride generation atomic absorption spectrometry

Acknowledgements

The financial support from the Scientific Grant Agency of the Ministry of Education of the Slovak Republic VEGA 1/0430/08 and VEGA 1/0159/08 is gratefully acknowledged.