A simple and rapid algal assay kit to assess toxicity of heavy metal-contaminated water. (15th January 2021)

• Record Type: Journal Article
• Authors: Eom, Heonseop; Park, Minseung; Jang, Am; Kim, Seunggyu; Oh, Sang-Eun
• Is Part Of: Environmental pollution. Volume 269(2021)
• Publication Date: 2021-01-15
• Subjects: Algal assay kit -- Chlorella vulgaris -- Heavy metal -- Oxygen evolution in gaseous phase; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2020.116135
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: This study presents a novel algal-based toxicity test suitable for simple and rapid assessment of heavy metal (Hg2+, Cr6+, Cd2+, Pb2+, or As3+)-contaminated water. A closed-system kit-type algal assay was developed using Chlorella vulgaris. Toxicity was assessed by oxygen evolution in the gaseous phase of the assay kits, which was measured via a needle-type oxygen sensor. Initial cell density, light intensity, and exposure time that enabled favorable test performance for the algal assay kits were 103 cells/mL, 250 μmol m-2s-1, and 18 h, respectively. Results from the heavy metal toxicity tests demonstrate that Hg2+, Cr6+, Cd2+, and Pb2+ are more toxic in inhibiting algal photosynthetic activity than As3+. The 18 h half-maximum effective concentrations (EC50) for Hg2+, Cr6+, Cd2+, Pb2+, and As3+ were determined to be 31.3 ± 0.5, 179.6 ± 7.5, 301.3 ± 6.1, 476.1 ± 10.5, and 2184.1 ± 31.1 μg/L, respectively. A strong correlation between oxygen concentrations in the headspace of the assay kits and chlorophyll a production indicates that oxygen evolution in the gaseous phase is able to represent algal photosynthetic activity and serve as the end-point in algal toxicity tests. High test sensitivity and reproducibility as well as an easy test protocol and rapid processing time make the algal assay kit a suitable tool for simple and rapid toxicity testing of heavy metal-contaminated water. Graphical abstract: Image 1 Highlights: A Chlorella vulgaris -based kit-type algal assay kit was developed. Oxygen evolution in gaseous phase was used as the end-point for toxicity analysis. Relative toxicity of heavy metals was as follows: Hg 2+ >Cr 6+ >Cd 2+ >Pb 2+ ≫As 3+ . The algal assay kit is suitable for rapid and simple heavy metal toxicity tests.